A PHASE 3, MULTICENTER, RANDOMIZED, DOUBLE-BLIND, PLACEBO CONTROLLED STUDY TO EVALUATE THE SAFETY AND EFFICACY OF PF 06939926 FOR THE TREATMENT OF DUCHENNE MUSCULAR DYSTROPHY
Phase: PHASE3
Conditions: Duchenne Muscular Dystrophy
Sponsor: Pfizer

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
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A PHASE 3, MULTICENTER, RANDOMIZED, DOUBLE-BLIND, 
PLACEBO-CONTROLLED STUDY TO EVALUATE THE SAFETY AND 
EFFICACY OF PF-06939926 FOR THE TREATMENT OF DUCHENNE 
MUSCULAR DYSTROPHY
Investigational Product Number:
fordadistrogene movaparvovec (PF-
06939926)
Investigational Product Name:
Not Applicable
United States (US) Investigational New 
Drug (IND) Number:
017598
European Clinical Trials Database 
(EudraCT) Number:
2019-002921-31
Protocol Number:
C3391003
Phase:
3
Sponsor Legal Address:
Pfizer Inc.
66 Hudson Boulevard East
New York, NY 10001
Short Title: A PHASE 3, RANDOMIZED, DOUBLE-BLIND, 
PLACEBO-CONTROLLED STUDY OF PF-06939926 IN DMD.
This document and accompanying materials contain confidential information belonging to Pfizer. Except as 
otherwise agreed to in writing, by accepting or reviewing these documents, you agree to hold this 
information in confidence and not copy or disclose it to others (except where required by applicable law) or 
use it for unauthorized purposes. In the event of any actual or suspected breach of this obligation, Pfizer 
must be promptly notified.
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Document History
Document 
Version Date
Amendment 15
28 December 2023
Amendment 14
07 June 2023
Amendment 13
06 April 2023
Amendment 12
30 September 2022
Amendment 11
09 September 2022
Amendment 10
10 June 2022
Amendment 9
13 May 2022
Amendment 8
04 March 2022
Amendment 7
04 March 2022
Amendment 6
01 September 2021
Amendment 5
14 April 2021
Amendment 4
28 December 2020
Amendment 3
24 November 2020
Amendment 2
05 October 2020
Amendment 1
18 March 2020
Original protocol
22 May 2019
This amendment incorporates all revisions to date, including amendments made at the 
request of country health authorities and IRBs/ECs and any protocol administrative change 
letter(s).
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Amendment 15 (28 December 2023)
Overall Rationale for the Amendment: 
To specify that PCD may occur when at least 90 randomized participants have received Year 
1 IP, which will provide > 95% power, as described in Section 9.2 of the protocol, to address 
the primary objective of the trial.
To clarify that if a participant/caregiver declines Year 2 IP administration, the participant will 
remain in the study for follow-up with a modified visit schedule.    
Additional incorporation of administrative changes and relevant corrections and 
clarifications. 
Protocol Amendment Summary of Changes Table
Description of Change
Brief Rationale
Section # and 
Name
Substantial Modification(s)
Clarified the timing of primary 
analysis (primary completion date).
A sample size of 90 participants 
randomized and who received 
Year 1 IP in the study provides 
>95% power (assuming a delta of 
3 from baseline in the NSAA 
total score; SD=3.5) to address 
the primary objective of the trial; 
this allows for the primary 
analysis to be conducted when at 
least 90 treated participants have 
completed Day 360 (Visit 19).
Sections 4.1. 
Overall Design.
9.3. Populations 
for Analysis.
9.5.. Interim 
Analyses.
Provided instructions that 
participants who decline Year 1 IP 
administration will be withdrawn 
from the study, and that those who 
decline Year 2 IP administration 
but remain in the study will not 
attend Visit 18 (if applicable),
Visits 20 to 30.2 or receive 
protocol-mandated glucocorticoid 
regimen. Prohibited concomitant 
medications do not apply to these 
participants.
To ensure follow-up while 
avoiding hospitalization, the very 
frequent safety visits post Year 2 
IP administration, and the receipt 
of high doses of glucocorticoids, 
given that there is no acutely 
increased risk of an immune 
reaction.  
Section 7.2.1.
Withdrawal of 
Consent.
1.3.1. Schedule 
of Activities –
Year 1 
(Screening to 
Year 1 Day 
360), footnote 
“f””. Also, in 
Appendices 
10.9. Italy, 
10.10. Japan, 
10.14. Germany, 
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Description of Change
Brief Rationale
Section # and 
Name
10.15. Russia 
and 10.16.
Israel.
Section 1.3.2. 
Schedule of 
Activities –
Year 2 and 
Long Term 
Follow Up, 
footnotes “bb” 
and “cc”. Also,
in Appendices
10.9. Italy, 
10.10. Japan, 
10.14. Germany, 
10.15. Russia 
and 10.16.
Israel.
Section 6.5.1. 
Permitted 
therapies.
Section 6.5.2. 
Prohibited 
Therapies.
Section 8.2.10. 
Post IP 
Intensified 
Safety 
Monitoring (at 
Year 1 and Year 
2).
Non-substantial Modification(s).
Replaced Estimand 1 (Treatment 
Policy) with the Primary Estimand 
for the primary endpoint.  
Clarified that death or loss of 
ambulation are identified as 
potential intercurrent events.   
Updated based on US FDA Type 
D meeting feedback received on 
26 June 2023.
Sections 1.1. 
Synopsis.
Section 3.1. 
Efficacy 
Objectives, 
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Description of Change
Brief Rationale
Section # and 
Name
Estimands, and 
Endpoints.
Section 9.1.1. 
Estimands
Replaced Estimand 1 (Treatment 
Policy) for secondary endpoints 
with Secondary Estimand(s).
Clarified that death or loss of 
ambulation are identified as 
potential intercurrent events.
Updated based on US FDA Type 
D meeting feedback received on 
26 June 2023.
Sections 1.1 
Synopsis.
Section 3.1. 
Efficacy 
Objectives, 
Estimands, and 
Endpoints.
Section 9.1.1. 
Estimands.
Removed Estimand 2 
(Hypothetical) for the primary 
endpoint.
Updated based on US FDA Type 
D meeting feedback received on 
26 June 2023 indicating 
challenges with interpretation of 
the hypothetical Estimand.
Sections 1.1 
Synopsis.
Section 3.1. 
Efficacy 
Objectives, 
Estimands, and 
Endpoints. 
Section 9.1.1. 
Estimands.
Updated “FAS” to “FAS (through 
Week 52)” and added definition of 
Efficacy Analysis Set (long-term)
Clarification that FAS analysis 
would be through Week 52 
(double-blind period).
Added definition for “Efficacy 
Analysis Set (Long-term)”, the 
analysis population to be used for 
long term efficacy analysis in the 
study.
Section 9.3. 
Populations for 
Analysis.
Clarified the p-value boundary to 
be used for secondary endpoints 
that are part of the gatekeeping 
procedure.
Clarified to preserve study wise 
Type-I error rate (across primary 
and secondary endpoints).
Section 1.1. 
Synopsis.
Section 9.1. 
Estimands and 
Statistical 
Hypotheses.
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Description of Change
Brief Rationale
Section # and 
Name
Clarified that instructions for the 
management of SAEs of elevated 
troponin or myocarditis are 
provided in Sections 8.2.7 and 
8.2.8.  
To ensure that relevant 
instructions are easily accessed.
Section 9.5.1. 
Data Monitoring 
Committee.
Clarified that GLDH is not 
considered sensitive clinical data.
To clarify that ALT/AST but not 
GLDH kept blinded from sites 
and from the sponsor on Day 9 in 
Year 1 and Year 2.
Section 1.3.1
1.3.1. Schedule 
of Activities –
Year 1 
(Screening to 
Year 1 Day 
360), footnote 
“aa”.
Section 1.3.2 
1.3.2. Schedule 
of Activities –
Year 2 and 
Long Term 
Follow Up, 
footnote “x”.
Country 
Appendices: 9 
(Italy), 10 
(Japan), 14 
(Germany), 15 
(Russia) and 16 
(Israel).
Deleted a statement indicating that 
the primary analysis would be 
performed when all enrolled 
participants complete one year of 
observation following treatment. 
Deleted information regarding 
follow up in the study.
To align with other sections in 
the protocol. 
The information deleted from 
Section 2.1 is not part of the 
rationale for the study. 
Section 1.1. 
Synopsis.
Section 2.1. 
Study Rationale.
Inserted Section 10.10.8 and 
clarified that for sites in Japan the 
To correct an omission in the 
country appendix.
Appendix 10 
(Japan), Section 
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Description of Change
Brief Rationale
Section # and 
Name
local testing of haptoglobin is 
mandatory but the testing of 
“Other” analytes prothrombin time 
activated partial thromboplastin 
time, CRP, Amylase and Lipase) is 
optional.
8. Clinical 
Laboratory 
Tests.
Appendix 2. 
Clinical 
Laboratory 
Tests.
Clarifications and minor updates to 
the text.
To improve the accuracy of the 
text.
Updates 
throughout the 
protocol
Incorporation of updates made by 
the PACL (Protocol Administrative 
Change Letter) for Study C3391003 
letter, dated 22 November 2023 to 
indicate that during periods of 
significant study delay for 
operational or administrative 
causes, participants from sites in 
Israel will be monitored 
approximately every 6 months.
To allow continuous monitoring 
for periods of significant delay in 
study conduct.
Section 1.3.2
Schedule of 
Activities –
Year 2 and 
Long Term 
Follow Up, 
footnote “a”.
Section 5.3.2
Year 2 IP 
Administration 
Eligibility.
Country 16: 
Israel.
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TABLE OF CONTENTS
LIST OF TABLES...................................................................................................................16
LIST OF FIGURES .................................................................................................................16
1. PROTOCOL SUMMARY...................................................................................................17
1.1. Synopsis ..................................................................................................................17
1.2. Schema ....................................................................................................................21
1.3. Schedule of Activities (SoA)...................................................................................22
1.3.1. Schedule of Activities – Year 1 (Screening to Year 1 Day 360)................22
1.3.2. Schedule of Activities – Year 2 and Long Term Follow Up......................36
2. INTRODUCTION ...............................................................................................................46
2.1. Study Rationale .......................................................................................................46
2.2. Background .............................................................................................................46
2.2.1. Duchenne Muscular Dystrophy..................................................................46
2.2.2. Dystrophin Role in Muscle.........................................................................48
2.2.3. Gene Therapy for the Treatment of DMD..................................................49
2.2.4. Nonclinical Pharmacodynamics .................................................................51
2.2.5. Nonclinical Immunogenicity ......................................................................51
2.2.6. Clinical Overview.......................................................................................52
2.2.7. Clinical Pharmacodynamics .......................................................................52
2.3. Benefit/Risk Assessment.........................................................................................53
2.3.1. Delay in Development ................................................................................53
2.3.2. Immunogenicity Risk Assessment..............................................................53
2.3.3. Risks Related to the Study Design..............................................................54
2.3.3.1. Daily Glucocorticoid Regimen..................................................54
2.3.3.2. Muscle Biopsy...........................................................................55
2.3.3.3. Immunity to AAV9 ...................................................................55
2.3.3.4. Participation in Future Clinical Studies ....................................55
2.3.3.5. Human Albumin........................................................................55
2.3.3.6. Sorbitol......................................................................................55
2.3.3.7. Gadolinium................................................................................56
3. OBJECTIVES, ESTIMANDS, AND ENDPOINTS ...........................................................56
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3.1. Efficacy Objectives, Estimands, and Endpoints......................................................56
3.2. Safety Objectives and Endpoints.............................................................................62
4. STUDY DESIGN.................................................................................................................64
4.1. Overall Design.........................................................................................................64
4.2. Scientific Rationale for Study Design.....................................................................66
4.2.1. Rationale for Inclusion of a Placebo Control Group ..................................66
4.2.2. Rationale for Selected Participant Population............................................66
4.2.3. Rationale for Selecting NSAA for the Primary Endpoint ..........................67
4.2.4. Rationale for Collection of Muscle Biopsies..............................................68
4.2.5. Rationale for Collection of Banked Biospecimens.....................................68
4.3. Justification for Dose ..............................................................................................68
4.4. End of Study Definition ..........................................................................................69
5. STUDY POPULATION......................................................................................................69
5.1. Inclusion Criteria.....................................................................................................69
5.2. Exclusion Criteria....................................................................................................70
5.3. Management of Participants Post Enrollment and Dosing Pause ...........................73
5.3.1. Study and Year 1 IP Administration Eligibility .........................................73
5.3.2. Year 2 IP Administration Eligibility...........................................................74
5.4. Siblings....................................................................................................................75
5.5. Lifestyle Considerations..........................................................................................76
5.5.1. Activity .......................................................................................................76
5.5.2. Hydration ....................................................................................................76
5.5.3. Hygiene.......................................................................................................76
5.6. Screen Failures ........................................................................................................77
5.7. Caregiver(s).............................................................................................................77
6. STUDY INTERVENTION..................................................................................................78
6.1. Study Intervention(s) Administered........................................................................78
6.1.1. Administration............................................................................................81
6.2. Preparation/Handling/Storage/Accountability ........................................................83
6.2.1. Preparation and Dispensing........................................................................85
6.3. Measures to Minimize Bias: Randomization and Blinding.....................................86
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6.3.1. Allocation to Investigational Product .........................................................86
6.3.2. Breaking the Blind......................................................................................86
6.3.3. Sensitive Clinical Data ...............................................................................87
6.4. Study Intervention Compliance...............................................................................89
6.5. Concomitant Therapy..............................................................................................89
6.5.1. Permitted Therapies....................................................................................89
6.5.2. Prohibited Therapies...................................................................................93
6.5.3. Rescue Medicine.........................................................................................94
6.6. Dose Modification...................................................................................................94
6.7. Intervention After the End of the Study..................................................................94
7. DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL...........................................................................94
7.1. Discontinuation of Study Intervention ....................................................................94
7.1.1. Temporary Discontinuation........................................................................97
7.1.2. Rechallenge.................................................................................................97
7.2. Participant Discontinuation/Withdrawal From the Study.......................................97
7.2.1. Withdrawal of Consent...............................................................................98
7.3. Lost to Follow-Up ...................................................................................................99
8. STUDY ASSESSMENTS AND PROCEDURES...............................................................99
8.1. Efficacy Assessments............................................................................................101
8.1.1. North Star Ambulatory Assessment (NSAA)...........................................101
8.1.2. Ankle Range of Motion (ROM) ...............................................................101
8.1.3. Muscle Biopsies........................................................................................101
8.1.4. Forced Vital Capacity (FVC)....................................................................103
8.1.5. Actigraphy ................................................................................................103
8.1.6. Ambulatory Status/Loss of Ambulation ...................................................103
8.1.7. Clinical Outcome Assessments.................................................................104
8.1.7.1. Caregiver-Completed Assessments.........................................104
8.1.7.2. Participant Completed Assessments........................................105
8.1.7.3. Clinical Evaluator-Completed Assessment.............................106
8.1.8. Rater Qualifications..................................................................................106
8.2. Safety Assessments ...............................................................................................106
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8.2.1. Physical Examinations..............................................................................107
8.2.2. Neurological Examinations ......................................................................107
8.2.3. Height and Weight Measurements............................................................107
8.2.4. Vital Signs ................................................................................................108
8.2.5. Electrocardiograms...................................................................................108
8.2.6. Echocardiogram........................................................................................109
8.2.7. Cardiac Troponin I....................................................................................109
8.2.8. Cardiac MRI .............................................................................................110
8.2.8.1. Management of Incidental Findings........................................111
8.2.9. Clinical Safety Laboratory Assessments ..................................................111
8.2.10. Post IP Intensified Safety Monitoring (at Year 1 and Year 2) ...............112
8.2.11. Additional Safety Monitoring.................................................................114
8.2.12. Local and Central Laboratory Testing....................................................114
8.2.13. Mood and Behavior Risk Monitoring.....................................................115
8.2.14. Pregnancy Testing ..................................................................................116
8.3. Adverse Events and Serious Adverse Events........................................................116
8.3.1. Time Period and Frequency for Collecting AE and SAE Information.....116
8.3.1.1. Reporting SAEs to Pfizer Safety.............................................117
8.3.1.2. Recording Nonserious AEs and SAEs on the CRF.................117
8.3.2. Method of Detecting AEs and SAEs ........................................................118
8.3.3. Follow-up of AEs and SAEs.....................................................................118
8.3.4. Regulatory Reporting Requirements for SAEs.........................................118
8.3.5. Environmental Exposure, Exposure During Pregnancy or 
Breastfeeding, and Occupational Exposure...................................................119
8.3.5.1. Exposure During Pregnancy....................................................119
8.3.5.2. Exposure During Breastfeeding ..............................................120
8.3.5.3. Occupational Exposure ...........................................................121
8.3.6. Cardiovascular and Death Events.............................................................121
8.3.7. Disease-Related Events and/or Disease-Related Outcomes Not 
Qualifying as AEs or SAEs............................................................................121
8.3.8. Adverse Events of Special Interest...........................................................121
8.3.8.1. Lack of Efficacy......................................................................121
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8.3.9. Medical Device Deficiencies....................................................................121
8.3.10. Medication Errors...................................................................................122
8.4. Treatment of Overdose..........................................................................................122
8.5. Pharmacokinetics ..................................................................................................123
8.6. Pharmacodynamics................................................................................................123
8.7. Genetics.................................................................................................................123
8.7.1. Specified Genetics ....................................................................................123
8.7.2. Banked Biospecimens for Genetics..........................................................123
8.8. Biomarkers ............................................................................................................124
8.8.1. Specified Gene Expression (RNA) Research ...........................................124
8.8.2. Specified Protein Research.......................................................................124
8.8.3. Specified Metabolomic Research .............................................................124
8.8.4. Banked Biospecimens for Biomarkers .....................................................124
8.8.5. Viral Vector Shedding Analysis ...............................................................125
8.8.6. Study C3391007 Household Contact Immunogenicity............................125
8.9. Health Economics .................................................................................................125
8.9.1. Healthcare Resource Utilization Questionnaire – Caregiver 
(HRU:CG)......................................................................................................125
8.9.2. Work Productivity and Activity Impairment DMD Questionnaire –
Caregiver (WPAI:DMD Caregiver)...............................................................126
8.10. Immunogenicity ..................................................................................................126
8.10.1. Neutralizing Antibody to AAV9 ............................................................126
8.10.2. ELISpot...................................................................................................126
8.10.3. Anti-drug Antibodies..............................................................................127
9. STATISTICAL CONSIDERATIONS ..............................................................................127
9.1. Estimands and Statistical Hypotheses...................................................................127
9.1.1. Estimands..................................................................................................128
9.2. Sample Size Determination...................................................................................129
9.3. Populations for Analysis .......................................................................................129
9.4. Statistical Analyses ...............................................................................................130
9.4.1. Efficacy Analyses .....................................................................................130
9.4.2. Safety Analyses ........................................................................................132
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9.4.2.1. Electrocardiogram Analyses....................................................132
9.5. Interim Analyses ...................................................................................................132
9.5.1. Data Monitoring Committee.....................................................................133
10. SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS........................................................................................................135
10.1. Appendix 1: Regulatory, Ethical, and Study Oversight Considerations.............135
10.1.1. Regulatory and Ethical Considerations ..................................................135
10.1.1.1. Reporting of Safety Issues and Serious Breaches of the 
Protocol or ICH GCP.......................................................................135
10.1.2. Financial Disclosure ...............................................................................136
10.1.3. Informed Consent Process ......................................................................136
10.1.4. Data Protection .......................................................................................137
10.1.5. Dissemination of Clinical Study Data ....................................................138
10.1.6. Data Quality Assurance ..........................................................................139
10.1.7. Source Documents..................................................................................140
10.1.8. Use of Medical Records..........................................................................140
10.1.9. Study and Site Start and Closure ............................................................141
10.1.10. Publication Policy.................................................................................142
10.1.11. Sponsor’s Qualified Medical Personnel ...............................................143
10.2. Appendix 2: Clinical Laboratory Tests ...............................................................144
10.3. Appendix 3: Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting ....................................................................148
10.3.1. Definition of AE .....................................................................................148
10.3.2. Definition of SAE...................................................................................149
10.3.3. Recording/Reporting and Follow-up of AEs and/or SAEs.....................151
10.3.4. Reporting of SAEs..................................................................................154
10.4. Appendix 4: Contraceptive and Barrier Guidance ..............................................155
10.4.1. Male Participant Reproductive Inclusion Criteria..................................155
10.5. Appendix 5: Genetics..........................................................................................156
10.6. Appendix 6: Liver Safety: Suggested Actions and Follow-up Assessments ......157
10.7. Appendix 7: ECG Findings of Potential Clinical Concern .................................159
10.8. Appendix 8: Country-Specific Requirements .....................................................160
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10.8.1. France Contrat Unique............................................................................160
10.9. Appendix 9. Italy-Specific Country Amendment ...............................................161
10.9.1. Schedule of Activities.............................................................................161
10.9.1.1. Schedule of Activities - Year 1 (Screening to Year 1 Day 
360)..................................................................................................161
10.9.1.2. Schedule of Activities - Year 2 and Long-Term Follow 
Up ....................................................................................................177
10.10. Appendix 10: Japan Appendix ..........................................................................187
10.10.1. Schedule of Activities...........................................................................187
10.10.1.1. Schedule of Activities - Year 1 (Screening to Year 1 
Day 360) ..........................................................................................187
10.10.1.2. Schedule of Activities – Year 2 and Long Term Follow 
Up ....................................................................................................202
10.10.2. Study Intervention Definition (per Japanese regulation)......................213
10.10.2.1. Reporting Criteria................................................................213
10.10.2.2. Reporting Procedures ..........................................................213
10.10.3. Study Design.........................................................................................213
10.10.4. Post IP Intensified Safety Monitoring (at Year 1 and Year 2) .............214
10.10.5. Regulatory Reporting Requirements for SAEs.....................................214
10.10.6. Reporting of Safety Issues and Serious Breaches of the Protocol or 
ICH GCP........................................................................................................214
10.10.7. Study Intervention(s) Administered .....................................................215
10.10.8. Clinical Laboratory Tests .....................................................................218
10.11. Appendix 11: Alternative Measures During Public Emergencies.....................221
10.11.1. Telehealth Visits...................................................................................221
10.11.2. Alternative Facilities for Safety Assessments ......................................221
10.11.2.1. Laboratory Testing ..............................................................221
10.11.3. Home Health Visits...............................................................................222
10.12. Appendix 12: Retrospective Assessment of Exclusion Criterion 15 ................223
10.12.1. Retrospective Assessment of Original Exclusion Criterion 15 ............223
10.12.2. Retrospective Assessment of Updated Exclusion Criterion 15............223
10.13. Appendix 13: DMD Long-Term Safety and Effectiveness Follow-Up 
PASS Study .............................................................................................................225
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10.14. Appendix 14: Germany-Specific Country Amendment....................................226
10.14.1. Schedule of Activities – Year 1............................................................226
10.14.2. Schedule of Activities – Year 2............................................................240
10.14.3. Inclusion Criteria ..................................................................................249
10.14.4. Exclusion Criteria.................................................................................250
10.15. Appendix 15: Russia Appendix.........................................................................253
10.15.1. Schedule of Activities – Year 1............................................................253
10.15.2. Schedule of Activities – Year 2 and Long Term Follow Up................267
10.15.3. Clinical Laboratory Tests .....................................................................277
10.16. Appendix 16: Israel Appendix ..........................................................................281
10.16.1. Schedule of Activities – Year 1 (Screening to Year 1 Day 360)..........281
10.16.2. Schedule of Activities – Year 2 and Long Term Follow Up................295
10.17. Appendix 17: Protocol Amendment History.....................................................305
10.18. Appendix 18: Abbreviations .............................................................................357
11. REFERENCES ................................................................................................................361
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LIST OF TABLES
Table 1.
Brief Overview of the Study Periods........................................................65
Table 2.
Routine Local Laboratory Testing in Year 1 and Year 2 .......................115
Table 3.
Protocol Required Safety Laboratory Assessments................................144
Table 4.
Protocol Required Safety Laboratory Assessments................................218
Table 5.
Protocol Required Safety Laboratory Assessments in Russia................277
LIST OF FIGURES
Figure 1.
The Dystrophin-associated Glycoprotein Complex (DGC) .....................49
Figure 2.
Schematic of the Domain Components in Full-Length Dystrophin, a 
Mini-Dystrophin Identified in a BMD Patient and a Mini-
Dystrophin tested in DMD Patients..........................................................50
Figure 3.
Management of Elevated Cardiac Troponin I (cTn-I)/Cardiac 
Troponin T (cTn-T) values .....................................................................110
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CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
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1. PROTOCOL SUMMARY 
1.1. Synopsis 
Short Title: A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study of PF-
06939926 in DMD.
Rationale
The purpose of the study is to demonstrate the safety and efficacy of fordadistrogene 
movaparvovec (PF-06939926) treatment in participants with DMD to support regulatory 
review for marketing authorization.
Objectives, Estimands, and Endpoints
The primary objective of the study is to demonstrate superior efficacy of treatment with 
fordadistrogene movaparvovec as compared to placebo. The table below describes the 
primary and secondary objectives, estimands, and endpoints. Additional exploratory 
objectives and endpoints address data collected after the time of the primary analysis 
including those for participants receiving fordadistrogene movaparvovec in Year 2 (Cohort 
2) and those collected in the long-term follow-up. 
Objectives
Endpoints
Estimands
Primary: 
Primary: 
Primary:
To demonstrate superior 
efficacy of treatment with 
fordadistrogene 
movaparvovec as 
compared to placebo 
based on change from 
Baseline in the North Star 
Ambulatory Assessment 
(NSAA).
Change from Baseline at 
Week 52 in the NSAA total 
score.
Primary Estimand: 
Population: Boys with a genetic diagnosis of 
DMD who are ambulatory and age ≥4 to 
<8 years;
Variable: Change from Baseline at Week 52 in 
the NSAA total score;
Death or loss of ambulation are identified as 
potential intercurrent events. 
Population-level summary: difference in mean 
changes from Baseline at Week 52 in the NSAA 
total score between fordadistrogene 
movaparvovec and placebo.
Secondary: 
Secondary: 
Secondary:
To quantify the 
mini-dystrophin 
expression level in the 
muscle of participants 
treated with 
Change from Baseline in 
percent normal 
mini-dystrophin expression 
level in biceps brachii muscle 
biopsies at Day 360 using a 
Secondary Estimand(s):
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Objectives
Endpoints
Estimands
fordadistrogene 
movaparvovec. 
liquid chromatography mass 
spectrometry (LC-MS) assay.
Population: Boys with a genetic diagnosis of 
DMD who are ambulatory and age ≥4 to 
<8 years;
Variable: Each secondary endpoint;
Death or loss of ambulation are identified as 
potential intercurrent events.
Population-level summary: difference in means 
between fordadistrogene movaparvovec and 
placebo for each secondary endpoint.
To characterize the 
distribution of 
mini-dystrophin 
expression in the muscle 
of participants treated 
with fordadistrogene 
movaparvovec.
Change from Baseline in 
percent of muscle fibers 
expressing mini-dystrophin in 
biceps brachii muscle biopsies 
at Day 360 as assessed by 
immunofluorescence.
To characterize the 
change in serum creatine 
kinase (CK) 
concentration in 
participants treated with 
fordadistrogene 
movaparvovec as 
compared to placebo.
Change from Baseline at 
Week 52 in serum CK 
concentration.
To characterize the skills 
gained, based on the 
individual items of the 
NSAA, in participants 
treated with 
fordadistrogene 
movaparvovec as 
compared to placebo.
Number of skills gained at 
Week 52 based on the 
individual items of the NSAA.
To characterize the skills 
either improved or 
maintained, based on the 
individual items of the 
NSAA, in participants 
treated with 
fordadistrogene 
movaparvovec as 
compared to placebo.
Number of skills either 
improved or maintained at 
Week 52 based on the 
individual items of the NSAA.
To characterize the 
10-meter run/walk 
velocity in participants 
treated with 
fordadistrogene 
movaparvovec as 
compared to placebo.
Change from Baseline at 
Week 52 in the 10 meter 
run/walk velocity.
To characterize the rise 
from floor velocity in 
participants treated with 
fordadistrogene 
Change from Baseline at 
Week 52 in the rise from floor 
velocity.
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Objectives
Endpoints
Estimands
movaparvovec as 
compared to placebo.
To characterize the 
functional health status in 
participants treated with 
fordadistrogene 
movaparvovec as 
compared to placebo.
Change from Baseline at 
Week 52 in the Modified 
Pediatric Outcomes Data 
Collection Instrument 
(PODCI): Transfer and Basic 
Mobility Core Scale (Pediatric 
Parent).
Change from Baseline at 
Week 52 in the Modified 
PODCI: Sports and Physical 
Functioning Core Scale 
(Pediatric Parent).
Overall Design
This is a Phase 3, global, multi-center, randomized, double-blind, placebo-controlled study in 
ambulatory male participants, ages ≥4 to <8 years, with a genetic diagnosis of DMD who are 
on a stable daily regimen of glucocorticoids. Eligible participants will be randomized into 
Cohort 1 or Cohort 2 in a 2:1 fashion and stratified by their age at Screening (<6 or ≥6 years 
old). Study enrollment will be managed to ensure that no more than approximately 55% of 
dosed participants are in either of the Screening age strata. Enrollment will be assessed 
periodically, and if an imbalance is noted, then enrollment of the overrepresented stratum 
may be paused until a more balanced distribution is achieved. Cohort 1 (approximately 
66 participants) will receive a single dose of fordadistrogene movaparvovec on Day 1 
(Visit 3) and a single dose of placebo at Day 390 (Visit 20). Cohort 2 (approximately 
33 participants) will receive a single dose of placebo on Day 1 (Visit 3) and a single dose of 
fordadistrogene movaparvovec at Day 390 (Visit 20), if they remain eligible. 
Number of Participants
A sufficient number of participants will be screened to achieve a total of approximately 
99 participants in the FAS across two strata (age <6 years and age ≥6 years) with no more 
than approximately 55% of dosed participants in either of the Screening age strata.
This sample size is based on the primary efficacy endpoint of change from Baseline at 
Week 52 in the NSAA total score. The above sample size (assuming 3 participants will drop 
out of the study prior to Week 52) will provide 98% power to detect a treatment difference 
(fordadistrogene movaparvovec – placebo) of 3.0. These calculations are based on =0.05 
(two-sided), a 3-look group-sequential design with a gamma family (-1) spending function to 
determine the efficacy boundary, a gamma family (-4) spending function for the non-binding 
futility boundary, a common standard deviation of 3.5, and using the normal approximation 
of the test statistic for the comparison between two means. 
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Screen failures are defined as participants who consent to participate in the clinical study but 
are not subsequently randomized to a cohort. 
Intervention Groups and Duration
In the context of this study, treatment will consist of two single intravenous infusions, one of 
fordadistrogene movaparvovec and one of placebo. Fordadistrogene movaparvovec will be 
administered as a dose of 2E14 vg/kg. The term investigational product (IP) is used to refer 
to either fordadistrogene movaparvovec or placebo. A single intravenous infusion of IP will 
be delivered over approximately 2 to 4 hours with the timing and sequence as follows: 

Cohort 1 will receive a single dose of fordadistrogene movaparvovec on Day 1 (Visit 
3) and a single dose of placebo at Day 390 (Visit 20); 

Cohort 2 will receive a single dose of placebo on Day 1 (Visit 3) and a single dose of 
fordadistrogene movaparvovec at Day 390 (Visit 20), if they remain eligible. 
All participants will be followed for 5 years after the administration of fordadistrogene 
movaparvovec such that total time on study will be approximately 5 years for Cohort 1 and 6 
years for Cohort 2. 
Data Monitoring Committee: Yes
An external data monitoring committee (E-DMC) will be used to provide an ongoing 
objective, unblinded assessment of safety and efficacy.
Statistical Methods
Primary Estimand: For the primary analysis, change from Baseline at Week 52 in the NSAA 
total score will be analyzed using a mixed model repeated measures approach including visits 
through Week 52 where NSAA is assessed. Baseline NSAA total score is defined as the last 
non-missing NSAA total score collected prior to Year 1 IP administration. The analysis will 
be based on the Full Analysis Set (FAS) (regardless of adherence to glucocorticoid regimen) 
and missing data will not be explicitly imputed. The model will include fixed effects for 
treatment (class variable), visit (class variable), treatment by visit interaction, Baseline 
NSAA total score (continuous variable), Screening age (continuous variable), Baseline 
NSAA total score by visit interaction, and Screening age by visit interaction with an 
unstructured covariance matrix to describe the correlation among different visits from the 
same participant. Alternative covariance structures to address any issues with model 
convergence will be specified in the statistical analysis plan (SAP). Estimates at Week 52 of 
the mean changes from Baseline and 95% confidence intervals along with the mean 
treatment group difference, two-sided p-value, and two-sided 95% confidence interval for the 
mean difference will be provided.
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1.2. Schema
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1.3. Schedule of Activities (SoA)
The SoA table provides an overview of the protocol visits and procedures. Refer to the STUDY ASSESSMENTS AND 
PROCEDURES section of the protocol for detailed information on each procedure and assessment required for compliance with the 
protocol. 
The investigator may schedule visits (unplanned visits) in addition to those listed in the SoA table, in order to conduct evaluations or 
assessments required to protect the well-being of the participant.
Alternate versions of the SoA for sites in Italy (see Appendix 9), Japan, (see Appendix 10), Germany (see Appendix 14), Russia (see 
Appendix 15) and Israel (see Appendix 16) are provided.
1.3.1. Schedule of Activities – Year 1 (Screening to Year 1 Day 360)
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Informed 
consent/assent
X
Inform caregivers 
about study 
C3391007dd
X
Demography
X
Medical history
Xii
Medication history
X
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Review of 
inclusion/exclusion 
criteria
X
X
Eligibility for Year 
1 IP 
administrationv
X
Hospital stayjj
X




X
Physical 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
Weight
X
X
X
X
X
X
X
Height
X
X
X
X
X
X
Vital signs (supine 
BP, respiratory 
rate, PR, body 
temp, and O2 
saturation)i,j
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGk
X
X
X
X
X
X
CBCL
X
X
X
g
Randomization
Xbb
Laboratory Assessmentsl
Blood Samples
NAb
X
(X)cc
X
X
X
g
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
ADA to 
mini-dystrophin 
and AAV9
X
Xff
Xff
Xff
X
X
X
X
g
ELISpot to 
mini-dystrophin 
and AAV9
X
X
X
g
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
g
Clinical safety 
(hematology, 
other)l
X
X
X
X
X
X
X
X
X
X
X
X
g
Chemistry and 
hepatic safety l
X
X
X
X
X
Xee
X
X
X
X
X
X
X
X
X
Post IP intensified 
safety 
monitoringl,w
X
X
X
X
X
Local and central 
laboratory testingaa
Xll
X
X
X
X
X
X
X
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
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CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 25
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
International 
normalized ratio 
(INR),
Hepatitis A virus 
(anti-HAV) 
immunoglobulin M 
Hepatitis B surface 
antigen,
Hepatitis C 
antibodyl
X
X
Biomarker 
(creatine kinase)l
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked 
biospecimens for 
biomarkersm
X
X
X
Banked 
biospecimens for 
geneticsn
X
Urine Samples
Clinical safety 
(urinalysis)l
X
X
X
X
X
X
X
X
X
X
g
Banked 
biospecimens for 
biomarkersm
X
X
X
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
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CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 26
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Saliva Samples
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Tissue Samples
Muscle biopsyo
X
Xx
Imaging 
Assessments
Echocardiogramp
X
X
X
g
Cardiac MRIgg
Xhh
Xhh
Functional Assessments
FVCq,y
X
X
X
g
NSAAq
X
X
X
X
X
X
X
Ankle range of 
motion 
X
X
X
X
X
X
X
Ambulatory status
Xr
X
X
X
X
X
Actigraphys
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentt
X
X
X
X
EQ-5D-Y Proxyt
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGt
X
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 27
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Participant-completed
EQ-5D-Yt
X
X
Clinical evaluator-completed
CGISq
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
WPAI:DMD 
Caregiver
X
Interventions
Protocol-mandated 
glucocorticoid 
regimenu
X
X













X
Background 
glucocorticoid 
regimen
X
X
X




IP administration
X
Meningococcal 
vaccine
X
X
Ongoing 
monitoring
Concomitant 
medications
X





















X
Serious and 
nonserious adverse 
event monitoring 
X





















X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 28
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9=adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG=electrocardiogram; ELISpot=Enzyme-Linked ImmunoSpot; EQ-5D-Y=EuroQol 5 
Dimensions–Youth; FVC=Forced Vital Capacity; IP=investigational product; Men ACWY=Meningococcal serogroups A, C, W, and Y; NAb=neutralizing antibodies; 
NSAA=North Star Ambulatory Assessment; PGIS=patient global impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; temp=temperature; PR=pulse 
rate. Schedule of Activities – Year 2 and Long-Term Follow Up
a.
Visit 1 – Screening Visit 

During screening, participants and caregiver(s) will be assessed for study eligibility in accordance with the Inclusion/Exclusion Criteria as described in Section 5.1 and 
Section 5.2; 

Visit 1 must be conducted over the course of 2 days. The investigator will decide which of the schedules below they will follow and inform the study team:

Schedule A:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. Second day: should take place the next day or as soon as possible, 
after the first day: clinical safety (See Appendix 2), INR, cardiac troponin I.

Schedule B:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers and viral vector shedding. Second day: must take place only when the results of the test for 
NAb to AAV9 are available. The time between the first and second day of the Screening Visit is expected to be between 3-4 weeks (based on the time to 
obtain the results of the NAb to AAV9 test). Only participants with a negative test for NAb to AAV9 will perform the rest of the Visit 1 assessments as per 
SoA. This includes the collection of blood and urine for: clinical safety tests (see Appendix 2), INR and cardiac troponin I. Participants with a positive test for 
NAb to AAV9 will be screen failed and will not attend the second day of Screening Visit (Visit 1).

Informed consent must be provided by the caregiver(s). The participant may also be required to provide assent in compliance with local regulations and institutional 
review board (IRB) requirements;
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 29
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Screening blood tests with results considered by the Investigator to be transient and inconsistent with the participant’s clinical condition may be repeated once during the 
screening period for confirmation of eligibility;

Demographics: Information such as date of birth, race and ethnicity and gender will be collected in compliance with local regulations;

Medical history will include results of genetic testing for confirmation of diagnosis of DMD. Results must confirm the presence of an abnormality (eg, deletion, 
duplication), or a point mutation in the dystrophin gene(s) which is consistent with the diagnosis of DMD. The mutation type will be reported. If the Investigator 
determines that the results are inconclusive, a repeat genetic testing will be allowed through the central laboratory at Screening (Visit 1) prior to any other assessments. 
In that case participants may return for the remainder of Screening (Visit 1) once results are confirmed (Section 8.7.1);

Medical history will also be reviewed for any significant medical history and concurrent illness(es) that required or are requiring specialist consultation or treatment;

Medication history: Complete medication history will include all prescription or nonprescription drugs, and dietary and herbal supplements taken within 30 days prior to 
the Screening Visit (Visit 1). The date the participant first started glucocorticoids for their DMD and the date of start of the background glucocorticoid regimen that the 
participant is taking at the time of Visit 1 (Screening Visit) must also be documented. In addition, the general immunization status including the immunization status 
against meningococcus, and any other vaccine(s) required by the eculizumab local prescribing information, must be documented;

Meningococcal vaccine: Participants who have no contraindications and who have not previously received a MenACWY vaccination; or whose last vaccination at the 
time of the Screening Visit (Visit 1) is outside the time period of active coverage specified by the vaccine manufacturer (Visit 1) must receive at least one dose of 
MenACWY vaccine as early as possible in the Screening Period and not later than 30 days before IP administration (see Section 6.5.1). Participants must also receive 
MenB vaccination if indicated by national vaccination guidelines. In addition, local eculizumab prescribing information, including additional vaccination and other 
requirements must also be followed (see Section 6.5.1).

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
b.
Visit 14 and Visit 19 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern 
and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood 
collection, may be performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory samples must be collected: 
Visit 14 (Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 30
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
Visit 19 (Week 52)
First day: anti-HAV immunoglobulin M, Hepatitis B surface antigen, Hepatitis C antibody (these tests will not be applicable for Cohort 1 participants confirmed to 
meet exclusion criterion 15 [see Section 5.2]), NAb to AAV9, ADA to mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. 
Second day: clinical safety, INR, cardiac troponin I, biomarker (creatine kinase). 
c.
Visit 2 – Baseline Visit

Meningococcal vaccine: Only applicable for participants who have not received this vaccination at Screening (please refer to footnote a);

For sites outside the US, the Baseline visit should occur at least 31 calendar days prior to the planned IP administration visit, Day 1 (Visit 3), to allow for timely delivery 
of IP to the site, unless notified of earlier or later IP delivery by the study team. For US sites the Baseline visit should occur at least 16 calendar days prior to the planned 
IP administration visit, Day 1 (Visit 3), to allow for timely delivery of IP to the site, unless notified of earlier or later IP delivery by the study team; 

IP will be shipped to site following confirmation of participant’s eligibility (Section 5.1 and Section 5.2) and randomization. The amount of IP to be shipped to the site 
for IP administration at Visit 3 will be based on the measurement of body weight at the Baseline Visit (Visit 2). Body weight measurement must be verified by two site 
personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site.

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6)
d.
Visit 3 – Week 1, Day 1 (Day of IP administration)

Prior to IP administration, the Investigator must confirm applicable IP eligibility criteria (Section 6.1.1);

Participants will be instructed not to take their background glucocorticoid dose on Day 1 (Visit 3);

Participants are to be admitted to the site;

The following assessments must be performed prior to IP administration: physical examination, urine sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone 1 to 4 hours prior to infusion of IP; 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 31
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

IP administration over approximately 2 to 4 hours (-15 minutes to +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site to enable prompt follow-up in the event of any emergent AEs through Day 14 (Visit 11), or longer if deemed necessary.
e.
Visits 12, 12.2, 13.2, 14.2 and 15

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
f.
Visit 18

This visit may be performed remotely (at or close to the participant’s home); in that case, it should include phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.

Amount of IP to be shipped to site for the IP administration on Day 390 (Visit 20) will be based on the measurement of body weight obtained at this visit. Body weight 
measurement must be verified by two site personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site. 
This visit is not applicable for Cohort 1 participants confirmed to meet exclusion criterion 15 (see Section 5.2).

For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be shipped to the site will be determined once the study has been 
restarted. Therefore, the weight collected at Day 328 (Visit 18) will not be entered into the interactive response technology drug management system during the dosing 
pause. Participants will be evaluated for Year 2 IP eligibility when the study is restarted.

May not be applicable for participants confirmed to meet exclusion criterion 15 or those who declined Year 2 IP administration (see Appendix 12 and Section 7.2.1).
g.
Early Discontinuation Visit

This visit is not applicable for participants who withdraw prior to Day 1 (Visit 3) or for Cohort 2 participants who are withdrawn from the study between Day 360 (Visit 
19) and Day 390 (Visit 20) (see Section 7.1).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 32
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only if the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
h.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable post-baseline unless safety concerns warrant full examination.
i.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
j.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
k.
12-Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
l.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 

For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 

On the following visits: Baseline Visit (Visit 2), Day 60 (Visit 14), Day 120 (Visit 16), Day 240 (Visit 17) and Day 360 (Visit 19), in which functional assessments 
(eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for 
additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
m.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 33
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
n.
Banked biospecimens for genetics are collected as described in Section 8.7.2.
o.
Open muscle biopsies will be obtained in approximately the first 15 participants randomized into Cohorts 1 and 2, and their siblings (with the potential to collect a 
maximum of 33 if needed), at sites that have been trained and certified by the Sponsor/Sponsor designee to collect open muscle biopsies, following administration of an 
anesthetic (eg, regional block or under general anesthesia) according to institutional standard practice, and only after any imaging and functional assessments scheduled for 
the same visit have been completed.  Baseline Visit muscle biopsies will be performed after randomization. If a muscle biopsy cannot be scheduled on the day of the 
Baseline Visit, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing.
p.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
q.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, ankle range of motion and FVC may be video recorded at the Day 1 
(Screening Visit), Baseline Visit (Visit 2), and at the annual visits (ie, Visits 19, 35, 37, 39, 41, 43). If CE re-training is required, the assigned master physiotherapist may 
request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be performed early in the course of the visit, to help reduce 
the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
r.
Ambulatory assessment at Screening (Visit 1) is based only on the ability to perform the 10 m run/walk, as assessed during the NSAA.
s.
An activity monitor will be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
t.
COAs will be completed by the caregiver on behalf of the participant and/or by the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
u.
Starting on Day 1 (Visit 3) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1).
v.
For eligibility for Year 1 IP administration please see Section 6.1.1.
w.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 34
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
x.
All participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo 2 post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-baseline muscle biopsy cannot be performed on the 
scheduled day, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing for the biopsy at Visit 19 and within 1 month of the day of the visit for 
the biopsy at Visit 41.
y.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
z.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) only after IP administration, as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a 
particular matrix (sample type) will be stopped when at least 2 consecutive negative results are observed in that matrix. See Section 8.8.5 for additional details.
aa.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 9 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data.  C3/C4 will also be sent to the central laboratory at Visits 6, 7, 8, 9, and 10. For more 
details, please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 4 and 5, see Appendix 2 and 
Appendix 10 for details.
bb. In order to ensure an adequate understanding and management of potential safety risks, the initial rate of randomization into the study will be limited. No more than 2 
participants per week will be randomized at the start of the study, until 4 participants have been observed for at least 2 weeks post IP administration. After that, the rate could 
be increased to no more than 3 participants randomized per week (until at total of 10 participants have been observed for at least 2 weeks post-IP administration). Thereafter, 
the rate of randomization could be further increased to no more than 5 participants randomized per week (until a total of 20 participants have been observed for at least 2 
weeks post-IP administration). After this time, no limits of the randomization rate will be imposed unless the study team, in consultation with the E-DMC, determines 
otherwise. For more details- please see Section 4.1.
cc.
The NAb to AAV9 blood samples at the Baseline Visit (Visit 2) will always be collected and sent to the Central Laboratory, but will only be analyzed and reviewed prior to 
Day 1 Visit (Visit 3) if the time between the first blood draw for NAb to AAV9 testing at the Screening Visit (Visit 1) or most recent test, if repeat blood draw(s) was required, 
and the Day 1 Visit (Visit 3) is expected to be more than 55 days, which is anticipated to occur rarely. Dosing cannot occur unless there is a negative test to AAV9 from a 
sample collected 55 or less days before the day of IP administration.
dd. For US sites, only when approved by the relevant Institutional Review Board.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 35
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
ee.
On Day 28 (Visit 12.2), only GLDH will be collected.
ff.
ADA to mini-dystrophin only.
gg. Investigators will discuss with the participant and/or their caregiver the importance of having a baseline cardiac MRI, even under general anesthesia, to be able to assess and 
manage potential cardiac adverse events during the study. This discussion and the decision to perform or not a baseline cardiac MRI will be documented in the participant's 
records. A participant requiring anesthesia or unable to undergo investigation with closed MRI (eg, metal implants) may be exempt, and will be allowed to be randomized in 
the study without a cardiac MRI. Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration 
(Section 2.3.3.7). If the site considers gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast 
administration will be performed. It is important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may 
be required in certain situations (Section 8.2.8).
hh. Cardiac MRI may be performed at any time between the first day of the Screening Visit (Visit 1) and the Day 1 Visit (Visit 3), and after randomization, as long as it is done 
before Day 1 (Visit 3). If a prior cardiac MRI was performed within 6 months of the Screening Visit (with gadolinium, or without gadolinium if contrast administration is 
contraindicated), and results are available, then a cardiac MRI at screening will not be performed. Only participants with a pre-IP administration cardiac MRI will have a 
follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
ii.
Participants will be assessed by a cardiologist at the Screening Visit, see Section 5.2, exclusion criteria 16 and 17.
jj.
Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed 
necessary by the Investigator (see Section 8.2.10). 
kk. This visit is for sites in Germany only and only to test cardiac troponin I. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s 
preference warrants in-person visit, this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local 
phlebotomist, as well as phone communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ll.
Only for sites in Russia 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 36
1.3.2. Schedule of Activities – Year 2 and Long Term Follow Up 
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Eligibility for Year 2 IP 
administrationr
X
Hospital staydd
X




X
Physical examinationg
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological examinationg
X
X
X
X
X
X
X
X
X
X
X
X
Height and Weight
X
X
X
X
X
X
X
Vital signs (supine BP, 
respiration, PR, body 
temp, and O2 saturation)h,i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGj
X
X
X
X
X
X
CBCL
X
X
X
Xe
Laboratory Assessmentsk
Blood Samples
 NAb to AAV9
X
X
X
Xe
  ADA to mini-dystrophin 
and AAV9
Xz
Xz
Xz
X
X
X
X
Xe
  ELISpot to mini-
dystrophin and AAV9
X
X
Xw Xe
Viral Vector Sheddingu
X
X
X
X
X
X
Xe
Clinical safety 
(hematology, other)k
X
X
X
X
X
X
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 37
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Chemistry and hepatic 
safetyk
X
X
X
X
Xy
X
X
X
X
X
X
X
X
X
X
Post IP intensified safety 
monitoringk,s
X
X
X
X
X
Local and central 
laboratory testingx
X
X
X
X
X
X
X
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
X
Biomarker (creatine 
kinase)k
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked biospecimens for 
biomarkersl
X
X
Urine Samples
Clinical safety (urinalysis)k
X
X
X
X
X
X
X
X
X
X
Xe
Banked biospecimens for 
biomarkersl
X
X
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Saliva Samples
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Tissue Sample
Muscle Biopsy
Xff
Imaging Assessments
Echocardiogramm
X
X
Xe
Cardiac MRIaa
Xaa
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 38
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Functional Assessments
FVCn,t
X
X
Xe
NSAAn
X
X
X
X
X
X
X
Ankle range of motion 
X
X
X
X
X
X
X
Ambulatory status
X
X
X
X
X
X
X
Actigraphyo
X
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentp
X
X
X
X
X
EQ-5D-Y Proxyp
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGp
X
X
X
X
X
X
X
Participant-completed
Modified PODCI –
Adolescentp
X
X
X
EQ-5D-Yp
X
X
X
PGISp
X
X
X
Clinical evaluator-completed
CGISn
X
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
X
X
WPAI:DMD Caregiver
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 39
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Study Interventions
Protocol-mandated 
glucocorticoid regimenq
X
X













X
Background glucocorticoid 
regimen
X



Xv
Xv
IP administration
X
Ongoing monitoring
Concomitant medications





















X
Serious and nonserious 
adverse event monitoring





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9= adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG = electrocardiogram; ELISpot= Enzyme-Linked ImmunoSpot; EQ-5D-Y= EuroQol 5 
Dimensions–Youth; FVC= Forced Vital Capacity; IP=investigational product; NAb=neutralizing antibodies; NSAA=North Star Ambulatory Assessment; PGIS= patient global 
impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; PR=pulse rate; temp=temperature.
a.
Visit 20 – Year 2, Week 1, Day 1

Prior to IP administration, the Investigator must confirm applicable Year 2 IP administration eligibility criteria (Section 7.1);

Participants are to be admitted to the site;

Participants will be instructed not to take their background glucocorticoid dose on Day 390 (Visit 20);

The following assessments must be performed prior to IP administration: Physical examination, blood collection (ELISpot to mini-dystrophin and AAV9), urine sample 
collection, ECG and vital signs; 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 40
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone approximately 1 to 4 hours prior to infusion of IP;

IP administration over approximately 2 to 4 hours (-15 minutes or +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site for at least 7 additional days to enable prompt follow-up in the event of any emergent AEs through Day 403 (Visit 28), or longer if 
deemed necessary.

If the time between the blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned Day 390 Visit (Visit 20) exceeds 13 weeks 
(90 days), due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), then the 
clinical safety laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP. The participant will not be withdrawn due to exceeding the time 
between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20), as described in Section 7.1.

If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), a participant’s Year 
2 IP administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be delayed for that participant until the pause is lifted. If the pause is not lifted 
within 6 months of the Day 360 (Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 ±7 days, and approximately every 6 months 
afterwards until the pause is lifted (or more frequently if considered necessary by the investigator) for sites in Israel, see Appendix 16.
b.
Visits 29, 29.2, 30.2, 31.2, and 32

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 41
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
c.
Visit 31 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern and/or participant 
preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood collection, may be 
performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory assessments must be collected as follows: 
Visit 31 (Year 2, Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
d.
Visit 42 and 43 – Long-term follow up Year 6

All participants will be followed for 5 years after receiving fordadistrogene movaparvovec. Therefore Visits 42 and 43 only apply to participants randomized to Cohort 2.
e.
Early Discontinuation Visit

This visit is not applicable for Cohort 2 participants who were withdrawn from the study between Day 360 (Visit 19) and Day 390 (Visit 20) (see Section 7).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical Safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 42
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f

FVC: Only If the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early
Discontinuation Visit.
f.
Visit Windows for Visits 20 through Visit 43

The number of days between each visit for Visit 20 (Year 2, IP administration) through Visit 43 must be maintained irrespective of the actual visit day of Visit 20, eg, if 
the actual visit day at Visit 20 is 392 (instead of 390), then Visit 21 will take place on Day 393 (instead of Day 391), etc. 
g.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable unless safety concerns warrant full examination.
h.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
i.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
j.
12 Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
k.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 
For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 
If the time between the blood draw for the clinical safety laboratory tests on Visit 19 (Day 360) and the planned Visit 20 (Day 390) exceeds 13 weeks (90 days due to 
operational or administrative reasons [eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays]), then the clinical safety 
laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP, but the participant will not be withdrawn due to exceeding the time between Visit 
19 (Day 360) and the planned Visit 20 (Day 390), as described in Section 7.1.
l.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
m.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 43
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 2, 
Week 6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
n.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, range of motion and FVC may be video recorded at the annual visits. If 
CE re-training is required, the assigned master physiotherapist may request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments 
should be performed early in the course of the visit, to help reduce the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of 
assessments please consult the Functional Assessment Manual. On the following visits: Day 449 (Visit 31), Day 509 (Visit 33), Day 629 (Visit 34) and Day 749 (Visit 35), in 
which functional assessments (eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the 
functional test; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
o.
An activity monitor may be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
p.
COAs will be completed by the caregiver on behalf of the participant and/or the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
q.
Starting on Day 390 (Visit 20) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1). If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety 
review, operational issues causing significant delays), participants must delay Year 2 IP administration, they will not receive the protocol-mandated glucocorticoid regimen 
until the pause is lifted and Year 2 IP administration takes place; they will remain on their background glucocorticoid regimen until then.
r.
For eligibility for Year 2 IP administration please see Section 7.1.
s.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
t.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 44
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb, 
cc
Visit 
22bb, 
cc
Visit 
23bb, 
cc
Visit 
24bb, cc
Visit 
25bb, cc
& 
26bb, cc
Visit 
27bb, 
cc
Visit 
28bb, 
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1bb,cc
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Visit Window (± days)
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u.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a particular matrix (sample type) will 
be stopped when at least 2 consecutive negative results are observed in that matrix.
v.
After two years (Day 749), any change to the background glucocorticoid regimen will be permitted (see Section 6.5.1).
w.
ELISpot to mini-dystrophin and AAV9 if a clinical event has occurred that, in the opinion of the Sponsor and/or the Investigator, could be due to an immunological reaction. 
If ELISpot is to be collected, these visits should be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. The 
following laboratory assessments must be collected as follows:
First day: NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase).
x.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 26  will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data. C3/C4 will also be sent to the central laboratory at Visits 23, 24, 25, 26, 27. For more 
details please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 21 and 22, see Appendix 2 and 
Appendix 10 for details.
y.
On Day 417 (Visit 29.2), only GLDH will be collected.
z.
ADA to mini-dystrophin only.
aa.
Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration (Section 2.3.3.7). If the site considers 
gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast administration will be performed. It is 
important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may be required in certain situations 
(Section 8.2.8). Only participants with a pre-IP administration cardiac MRI will have a follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35). 
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Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
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5, 6d
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3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
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bb. Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration (see Section 7.2.1) will not attend Visits 20 to 30.2 and 
therefore will not perform the corresponding tests and assessments. These participants will not receive their protocol-mandated glucocorticoid regimen at Year 2. For details 
on the retrospective assessment of exclusion criterion 15, please see Appendix 12..
cc.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not receive their protocol-mandated glucocorticoid 
regimen at Year 2. For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
dd. Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
ee.
This visit is for sites in Germany only and only to test cardiac troponin I. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s
preference warrants in-person visit, this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local 
phlebotomist, as well as phone communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ff.
A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo two post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-Baseline muscle biopsy cannot be scheduled on the 
day of Visit 19 or Visit 41, it may be performed at a later date, as long as it is at least 2 weeks before dosing, for the biopsy at Visit 19 and within 1 month of the day of the 
visit for the biopsy at Visit 41.
gg. Only for sites in Russia
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2. INTRODUCTION
The investigational product (IP), fordadistrogene movaparvovec (PF-06939926), is a gene 
therapy viral construct (AAV9.hCK.optiDys∆3978.spolyA), consisting of recombinant 
adeno-associated virus serotype 9 (AAV9) vector and single stranded deoxyribonucleic acid 
(DNA) encoding for a miniaturized version of the dystrophin protein (“mini-dystrophin”). 
The specific coding sequence of the mini-dystrophin gene (OptiDysΔ3978), encompassing 
domains minimally required for functionality, was chosen based on a published report of a 
patient and his relatives with a deletion that eliminates 46% of the protein who had a mild 
disease course consistent with Becker muscular dystrophy (BMD) [England et al., 1990].1
Cardiac and skeletal muscle specific transgene expression is mediated by the synthetic 
promoter, hybrid creatine kinase H [Hauser et al., 2000].2
Fordadistrogene movaparvovec is intended to be used as a gene replacement therapy, ie, to 
restore functional dystrophin expression in skeletal and cardiac muscle cells by direct 
replacement of the missing or dysfunctional protein with mini-dystrophin.
Complete information for this compound may be found in the latest version of the Single 
Reference Safety Document, which for this study will be the Investigator Brochure (IB).
2.1. Study Rationale 
The purpose of the study is to demonstrate the safety and efficacy of fordadistrogene 
movaparvovec in participants with DMD to support regulatory review for marketing 
authorization. 
2.2. Background
2.2.1. Duchenne Muscular Dystrophy
DMD is a severe, X-linked, progressive neuromuscular disease affecting approximately one 
in 3600 to 9300 live male births.3 It is caused by mutations in the dystrophin gene that 
eliminate or severely reduce the expression of functional dystrophin protein.4 The near lack 
of the dystrophin protein in skeletal muscles, including those required for respiration, and in 
the heart leads to muscle degeneration which results in loss of ambulation and premature 
death.5
First identified in 1987, the dystrophin gene is one of the largest human genes at 2.4 Mb and 
contains 79 exons.4,6,7 The most common forms of mutations that cause DMD are large 
deletion mutations of one or more exons (approximately 68%); however, large duplication 
mutations (approximately 11%), point mutations (approximately 11%), and small 
insertion/deletion mutations (approximately 7%) also occur.8 These gene mutations often 
lead to a frame shift mutation (ie, disruption of the reading frame) or generate a premature 
stop codon (ie, out of- frame) and result in absence or significant reduction in the level of 
functional dystrophin protein. In-frame deletions result in a milder form of muscular 
dystrophy, ie, Becker muscular dystrophy (BMD), in which patients express a smaller,
partially functional dystrophin protein. The deletions in BMD most often involve regions 
encoding the central rod-like domain, such that the C- and N-terminal domains can still make 
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the appropriate protein-protein interactions within the cell.7 There is a wide spectrum of 
clinical presentations of BMD, ranging from minor effects on lifestyle and lifespan to loss of 
ambulation in the late teens or early 20s. The most common cause of premature death in 
BMD patients is cardiac failure. 
The clinical course of DMD is a direct result of the rate of damage to the muscle tissue. 
Skeletal muscles that experience the greatest mechanical stress and have the largest diameter 
are damaged the fastest (Petrof et al., 1993).9 At approximately the age of 6, many of the 
lower extremity muscles begin to lose the ability to regenerate and the degenerative process 
becomes dominant.10 As necrosis continues, the loss of muscle is accompanied by an 
increase in fatty and connective tissue (Ramos et al., 2015),11 ultimately leading to the loss of 
ambulation by age 8-11 (Humbertclaude et al., 2012).12 With continued disease progression, 
functional loss of the muscles of respiration and the upper extremity can occur.13 DMD is a 
terminal disease and patients usually die in the third decade (Kieny P et al, 2013).14
Eventually, almost all DMD patients develop cardiomyopathy. (Aartsma-Rus et al., 2016)15
Respiratory and cardiac complications are major causes of disease-related morbidity and 
mortality.18
Standard of care guidelines for DMD multi-disciplinary teams have been developed and were 
published initially in 2010 and more recently in 2018.13,16,17,18,19 Current treatment 
recommendations are aimed at keeping the patient independent for as long as possible and 
preventing complications that result from weakness, reduced mobility, and cardiac and 
respiratory complications. 
Glucocorticoid therapy (prednisone, prednisolone, and deflazacort) has been used as the 
standard treatment for several years and is currently recommended to be discussed with 
caregivers when a patient is between 4 and 8 years of age. 16 Glucocorticoids can slow the 
rate of muscle deterioration in DMD and help children retain upper limb strength, respiratory 
function and prolong independent walking by a median of 3 years.16,20 Although there are 
clear benefits to patients with DMD, the numerous side effects associated with chronic 
glucocorticoid use limit treatment (Bushby et al., 2010; Prednisone Summary of Product 
Characteristics (SmPC) 2018).13,21
Currently, 5 drugs targeting dystrophin restoration have been approved. All are designed to 
interface with the transcription and translation machinery enabling the production of 
functional dystrophin protein. Translarna™ (ataluren; PTC Therapeutics) is intended to 
enable stop codon read-through in approximately 10% of DMD patients with erroneous stop 
signals (“nonsense” mutations”) in the dystrophin gene.22,23 Translarna received conditional 
marketing authorization by the European Medicines Agency (EMA) in July 2014; on
February 22, 2016, the Food and Drug Administration issued a Refuse to File Letter to PTC,
concluding that the application was not substantially complete to allow for substantial
review.24
EXONDYS 51™(eteplirsen, Sarepta Therapeutics) is designed to skip over mutations in the 
region of exon 51,25 which occurs in approximately 14% of DMD patients.23 This approach 
necessarily results in an ‘internally deleted’ protein which is somewhat shorter than the full-
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length protein. EXONDYS 51 was granted accelerated approval in September 2016 by the
US Food and Drug Administration based on the surrogate endpoint of increased dystrophin
protein production.26 The EMA announced a negative opinion for a conditional marketing 
authorization for EXONDYS 51 in May 2018 and confirmed its opinion in
September 2018 after re-examination.27 VYONDYS 53™(golodirsen; Sarepta Therapeutics)
and VILTEPSO™(viltolarsen; Nippon Shinyaku Pharma) are both designed to skip over
mutations in the region of exon 53.28,29 VYONDYS 53 is indicated for the “treatment of
DMD in patients who have a confirmed mutation of the DMD gene that is amenable to
exon 53 skipping”, which occurs in approximately 8% of DMD patients. VYONDYS 53 was
granted accelerated approval in December 2019 by the FDA based on the surrogate endpoint
of increased dystrophin protein production. VILTEPSO was granted accelerated approval in
August 2020 by the FDA based on an increase in dystrophin protein in skeletal muscle.30
AMONDYS 45™(casimersen; Sarepta Therapeutics) is designed to skip over mutations in
the region of exon 45, which occurs in approximately 9% of DMD patients;31
AMONDYS 45 was granted accelerated approval in February 2021 by the FDA based on the
surrogate endpoint of increased dystrophin protein production.32
In summary, treatment options are limited because glucocorticoids, which can be used by all
patients irrespective of underlying mutation, are symptomatic treatments that slow disease
progression only to a limited degree and have known safety issues, and the 3 therapies aimed
at restoring dystrophin levels are applicable to approximately 30% of the DMD population.
Therefore, there remains a significant unmet medical need for a therapy that will target the
underlying pathophysiology, significantly alter disease progression, and be efficacious for the
entire DMD population, irrespective of mutation type.
2.2.2. Dystrophin Role in Muscle
In muscle, dystrophin is localized at the cytoplasmic face of the sarcolemma membrane. 
Full-length dystrophin consists of an N-terminal actin-binding domain, a central large 
rod-like domain composed of spectrin-like repeats, and a cysteine-rich C-terminus that is 
connected to the dystrophin-associated glycoprotein complex (DGC), a large protein 
complex that forms a critical link between the cytoskeleton and the extracellular matrix.5 The 
primary function of dystrophin is to act as a shock absorber during muscle fiber contraction,
protecting the cell membrane from damage induced by the sheer force.15
When dystrophin is significantly reduced, the lack of protection from the stress of contraction 
leads to sarcolemmal damage, calcium influx, inflammation, and ultimately muscle cell death 
(ref). This same pathophysiological process occurs in all muscles, although the rate of 
damage depends on the degree of mechanical stress experienced and the size of the muscle 
(Petrof et al., 1993).9 Thus, muscles of the lower limb are affected first, followed by those of 
the upper limb and those required for respiration. 
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Figure 1.
The Dystrophin-associated Glycoprotein Complex (DGC)
Dystrophin acts as an important link between the internal cytoskeleton and the extracellular 
matrix. -dystroglycan (DG); -dystroglycan (DG) [Fairclough et al., 2013].33
Due to its pivotal role in the structure of muscle cells, dystrophin restoration, or replacement 
via gene transfer, requires generation of a form of the protein able to reassemble the DGC 
and support a mechanically strong link between the extra-cellular matrix and the cytoskeleton 
[Ehmsen et al., 2002].34 Based on examples of patients with BMD, the protein can retain this 
function even when a significant portion of its central rod-like domain is absent. 
2.2.3. Gene Therapy for the Treatment of DMD
DMD is an attractive candidate for gene transfer as it arises from mutations in a single gene. 
Many current gene therapy approaches utilize recombinant AAV (rAAV) vectors to deliver 
the transgene. rAAV vectors are based on a non-pathogenic, non-integrative, replication 
deficient member of the parvovirus family and are ideal candidates for muscle-directed gene 
therapy because of (i) their ability to target skeletal and cardiac muscle, (ii) the long-term 
persistence of the vector genome in transduced cells, and (iii) their lack of immunotoxicity. 
[Wang et al., 2000]35 Gene delivery using a variety of AAV serotypes has been investigated 
in clinical studies for diseases including hemophilia B, alpha-1 antitrypsin deficiency, 
lipoprotein lipase deficiency, Pompe disease, heart failure, and several muscular dystrophies, 
including DMD (www.clinicaltrials.gov). Use in this broad spectrum of disease areas is 
enabling a cumulative experience with the use of rAAV to deliver gene therapy, particularly 
with regard to safety. The AAV serotype 9 capsid has been shown to have particularly strong 
and efficient tropism for both skeletal and cardiac muscle, resulting in transduction 
throughout the body after systemic administration in several preclinical studies 
[Athanasopoulos et al., 2004; Zincarelli et al., 2008; Wang et al., 2009; Kornegay et al., 
2010].36,37,38,39
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Effective dystrophin restoration or replacement via gene therapy in muscle and 
cardiomyocytes requires generation of a dystrophin protein able to reassemble the DGC and 
support a structural link between the extracellular matrix and the cytoskeleton.11
A major hurdle in the use of recombinant AAV vectors in dystrophin gene therapy is their 
packaging capacity, which is approximately 4.7 kb, while the size of the full-length 
dystrophin complementary deoxyribonucleic acid is about 14 kb. To overcome this 
challenge, genes with partial deletions of the central rod-like domain that can be successfully 
packaged inside recombinant AAV vectors have been developed and have been shown in 
animal models to be functional (Figure 2). 33,40 The mini-dystrophin sequence used in 
fordadistrogene movaparvovec was designed based on the mutant form of the gene carried in 
a family of mildly affected patients with BMD in which ambulation was preserved until 
beyond age 50 (England et al., 1990)1 Thus, the therapeutic effect of fordadistrogene 
movaparvovec is anticipated to restore dystrophin function adequate to convert a DMD 
clinical course into a mild BMD course.
The fordadistrogene movaparvovec sequence has a large in-frame rod domain deletion and 
fits into AAV vectors even when muscle-specific promoters are incorporated.33,41 A depiction 
of the changes, relative to full-length dystrophin, in the family’s naturally occurring BMD 
mutation and in a representative mini-dystrophin gene construct is provided in Figure 2. The 
mini-dystrophin gene in fordadistrogene movaparvovec has a slightly shorter length but has 
the same functional domains as the BMD family’s mini-dystrophin protein (England et al., 
1990).1
Figure 2.
Schematic of the Domain Components in Full-Length Dystrophin, a 
Mini-Dystrophin Identified in a BMD Patient and a Mini-Dystrophin tested 
in DMD Patients
Adapted from Fairclough, et al. 2013.33
In animal models of DMD, the mini- or micro-dystrophins, contained within the recombinant 
AAV vectors have been shown to improve, though not completely normalize, the dystrophic 
phenotype.2,33,42,43 Restoration of the dystrophin-associated protein complex, stabilization of 
muscle degeneration, and improvements in muscle function have been demonstrated 
following delivery of truncated dystrophin genes at different stages of disease progression in 
the murine model for DMD.2,44,45,46 Across several different mini-dystrophin constructs, it 
has been noted that the ability of the expressed dystrophin proteins to protect muscle from 
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contraction-induced injury corresponds to both the structural elements included and to the 
expression levels of the therapeutic protein.43
2.2.4. Nonclinical Pharmacodynamics
A dose-finding study of fordadistrogene movaparvovec was conducted in DMD rats and 
demonstrated a dose-dependent increase in the mini-dystrophin protein expression levels and 
the percentage of fibers expressing mini-dystrophin, as well as a decrease in fibrosis. [Study 
PF-06939926_17Aug18_043355 -Mass Spectrometry (IA-LC-MS-MS) quantification of 
mini-dystrophin protein expression in rat efficacy study]. Additionally, increasing doses of 
fordadistrogene movaparvovec resulted in a dose-dependent decrease in muscle fatigue as 
measured by repeat grip testing in the DMD rats. The data from this dose-finding study in 
DMD rats suggested that 1E14 vg/kg is the minimally effective dose. Specifically, a dose of 
1E14 vg/kg resulted in expression of mini-dystrophin in skeletal muscle fibers and cardiac 
myofibers and was associated with normalization in absolute force and fatigability, as well as 
improvements in tissue architecture (connective tissue area and overall lesion score) and 
serum biomarkers. Additionally, expression of the transgene in muscle tissues and 
preservation of the functional responses persisted 6 months post-dose. 
A dose of 3E14 vg/kg was associated with increased transduction and dystrophin expression 
in muscles relative to that seen for 1E14 vg/kg. 
In a biodistribution study with fordadistrogene movaparvovec in the Golden Retriever model 
of Duchenne dog model, widespread but heterogenous tissue expression levels of the human 
mini-dystrophin transgene and protein was shown in a subset of the cohort. Histopathological 
assessments confirmed increased mini-dystrophin positive fibers in the skeletal muscles 
examined, including the diaphragm. In Golden Retriever model of Duchenne dog studies of 
mini-dystrophin candidates previously in development, widespread transduction of skeletal 
muscles and the heart, improvements in the histopathology of muscle tissue and 
improvement in several measures of function and extended survival were observed.
2.2.5. Nonclinical Immunogenicity
During the evaluation of systemic delivery of fordadistrogene movaparvovec at various doses 
in the DMD rat model, human mini-dystrophin was recognized by the host immune system; 
however, the humoral response detected against mini-dystrophin and the AAV9 capsid had 
no impact on the therapeutic efficacy of the fordadistrogene movaparvovec at 3 and 6 months 
post-infusion. Consistent with unpublished observations even when the systemic delivery of 
an AAV encoding for a foreign polypeptide elicits a detectable cellular immune response, it 
does not necessarily lead to destruction of the transduced cells. The route of administration is 
believed to be an important component of immune response outcome, with the intravenous 
(IV) route being the least immunogenic, at least in animal models, including rodents, dogs 
and nonhuman primates.
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2.2.6. Clinical Overview
The ongoing Phase 1b Study C3391001 is the first study of fordadistrogene movaparvovec in 
humans. It is an open-label, single ascending dose study designed to evaluate the safety and 
tolerability of the mini-dystrophin gene therapy in ambulatory participants with DMD. The 
study includes boys with a genetic diagnosis of DMD, age 4 to 12 years, inclusive, who are 
on a stable dose of glucocorticoids, can rise from the floor in <7 seconds, and are negative 
for neutralizing antibodies (NAb) to AAV9. 
As of 08 January 2020, 3 participants have been treated with the low dose (1E14 vg/kg) and 
6 participants have been treated with the high dose (3E14 vg/kg) of fordadistrogene 
movaparvovec. Muscle biopsies taken from the biceps brachii muscle at 2 months 
demonstrated robust mini-dystrophin expression. Fordadistrogene movaparvovec was safe 
and well-tolerated at the low dose, with the most common AEs (in 2 of 3 participants) being 
transient nausea (1 mild, 1 moderate) and moderate vomiting treated with an oral antiemetic 
(ondansetron); both events starting at approximately Day 2-5 following treatment. At the 
high dose, 5 of 6 participants experienced moderate vomiting and 3 of 6 participants 
experienced moderate nausea and headache (2 mild, 1 moderate), with one participant being 
re-admitted to the hospital on Day 5 post IP infusion for hydration and IV ondansetron, and 
thus qualifying as a serious adverse event (SAE). Two additional SAEs (in 2 different 
participants at high dose) reflected a clinical picture compatible with complement-mediated 
thrombotic microangiopathy consistent with atypical hemolytic uremic syndrome (aHUS) 
within two weeks post IP infusion, manifesting with thrombocytopenia, hemolysis, and 
reversible nephropathy. Medical management, including treatment with eculizumab was 
provided and led to recovering laboratory test results within 2-3 weeks. 
Following the most recent SAE involving complement activation, the Pfizer Benefit-Risk 
Committee, Pfizer Risk Management Committee, and assigned External Data Monitoring 
Committee (E-DMC) reviewed the two reported SAEs and full safety information, as well as 
preliminary evidence of mini-dystrophin expression from muscle biopsies and available data 
on the NSAA. The outcome of each of these reviews was that the existing safety monitoring 
remains adequate for mitigating risk and managing these events, and thus, supported the 
continuation of the trial at the current dose-level.
Study C3391001 will continue to enroll and treat additional participants prior to the start of 
Study C3391003. Thus, the additional information gained from observing the accruing safety 
data, from managing the clinical signs and symptoms of any AEs, and from assessing 
functional outcomes may be used to amend Study C3391003, as needed. 
2.2.7. Clinical Pharmacodynamics
As of 20 May 2019, in both the low and high dose cohorts of Study C3391001, muscle 
biopsies obtained at 2 months post-treatment were evaluated for mini-dystrophin expression 
and percent of positive fibers. The preliminary results provide some initial evidence of 
transduction.
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2.3. Benefit/Risk Assessment
Given the high unmet medical need for this progressive, fatal, genetic disorder, the potential 
benefit from gene therapy currently outweighs the known or potential risks. 
More detailed information about the known and expected benefits and risks, and reasonably 
expected adverse events (AEs) of fordadistrogene movaparvovec may be found in the latest 
version of the Investigator’s Brochure (IB) which is the single reference safety document 
(SRSD) for this study. 
An external data monitoring committee (E-DMC) will be used to provide an ongoing 
objective, unblinded assessment of safety and efficacy (Section 9.5.1). Regulatory authorities 
will be kept informed of any additional data (eg, results from non-clinical and clinical 
studies) which may affect the benefit:risk profile for fordadistrogene movaparvovec.
There are three areas of potential risk that are highlighted here, based either on observations 
from the non-clinical studies, from Study C3391001, or on potential immune reactions to 
gene therapy. 
2.3.1. Delay in Development
In the 90-day toxicology study in juvenile rats, the no observed adverse effect level
(NOAEL) was determined to be 3E14 vg/kg because several findings occurred at the next 
higher dose of 2E15 vg/kg. These findings included decreased body weight and food 
consumption and delayed skeletal and sexual maturation. Similar findings were not observed 
in any other non-clinical studies of fordadistrogene movaparvovec. Given the age range of 
the population included in Study C3391003, in which participants have not completed 
maturation of the sexual, skeletal, or muscle systems, there is a risk that development of these 
systems could be affected by therapy, although it is noted that these occurred in the rat study 
at nearly 10 times the clinical dose. It will be difficult to ascertain the effect of 
fordadistrogene movaparvovec on development of these systems in Study C3391003 since all 
participants are required to use daily glucocorticoids, which are also known to cause a delay 
in skeletal and sexual maturation [Prednisone SmPC].47
2.3.2. Immunogenicity Risk Assessment
Humoral and cellular immune responses against both the vector and the transgene may 
negatively impact the safety and efficacy of gene therapy and will be carefully monitored 
[Mingozzi et al., 2011].48 NAb to the vector could significantly reduce muscle cell 
transduction, and therefore participants with pre-existing NAb are excluded from the study. 
An immune response to the vector and/or the transgene following treatment can lead to 
inflammation of tissues that are transduced, such as liver, muscle, and heart, and/or to a 
systemic immune reaction, such as complement activation, that may result in damage to 
blood, renal, and possibly other systems. 
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In order to reduce the possibility of an immune reaction, participants will receive a single IV 
administration of methylprednisolone prior to the infusion of IP, followed by a 
protocol-mandated regimen of daily oral glucocorticoids for 3 months, as described in 
Section 6.5.1. 
In a number of on-going or completed clinical studies with AAV-based vectors, the most 
consistent treatment-emergent adverse reaction reported has been elevations in liver 
enzymes. Most reported events have resolved with the administration of glucocorticoids 
(Nathwani).49 To reduce the risk of liver injury associated with fordadistrogene 
movaparvovec, participants will receive a single IV administration of methylprednisolone 
prior to the infusion of IP, followed by a protocol-mandated regimen of oral glucocorticoids 
for 3 months. Liver injury will be monitored closely using laboratory assessments, including 
serum glutamate dehydrogenase (GLDH), which is a liver-specific enzyme and is not 
increased in the setting of muscle disease as is the case for AST and ALT (See Appendix 6).
Cases of skeletal muscle and cardiac injury have been observed in clinical studies of 
fordadistrogene movaparvovec. The potential for skeletal muscle injury is monitored 
primarily by physical signs and symptoms, and by measurements of CK, that are monitored 
on an ongoing basis by the unblinded medical monitor (see Section 6.3.3). The potential for 
cardiac injury is monitored using cardiac troponin I (see Section 8.2.7). Participants (and/or 
caregivers) should be instructed to contact the site if signs and symptoms of skeletal muscle 
and/or cardiac injury are observed (see Section 8.2.11).
Given the SAEs in the Phase 1b Study C3391001, in which subjects had a clinical picture of 
complement-mediated thrombotic microangiopathy consistent with atypical hemolytic 
uremic syndrome (aHUS) including thrombocytopenia, indicators of hemolysis, increased 
serum creatinine from baseline, or low C3 or C4, several risk mitigations have been included 
in Study C3391003 (see Section 8.2.10). 
2.3.3. Risks Related to the Study Design
2.3.3.1. Daily Glucocorticoid Regimen
All participants of this study will be on a background stable daily dose of glucocorticoids for 
at least 3 months prior to Screening (Visit 1) and will remain on this regimen for at least the 
first 2 years of the study. Treatment with glucocorticoids to help control the symptoms of 
DMD and to slow disease progression is a standard therapeutic approach in clinical practice 
and has been shown to have a positive benefit:risk ratio 
[https://www.niams.nih.gov/newsroom/spotlight-on-research/optimizing-steroid-treatment-
duchenne-muscular-dystrophy]. Given the cumulative side effects of these drugs, however, 
some physicians choose to wait until a patient begins declining in function to initiate them. 
There is a potential risk that initiating daily glucocorticoids in boys beginning at 4 years of 
age could have a long-term impact on their health and/or on the ability to use these 
medications later in life. This risk is mitigated in this study by allowing participants and their 
physicians to choose a regimen that they feel best suits the individual participant following 
completion of Year 2. On rare occasions, participants may develop adrenal insufficiency 
during the tapering of the protocol-mandated glucocorticoid treatment. Signs and symptoms 
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of adrenal insufficiency may include hypoglycemia, hyperkalemia, hyponatremia, orthostatic 
hypotension, hypotension, fatigue, weakness, myalgia, arthralgia, anorexia, abdominal pain, 
nausea, vomiting and/or diarrhea. Participants with signs or symptoms suggestive of adrenal 
insufficiency should be promptly evaluated and, if necessary, treated following local 
guidelines.
2.3.3.2. Muscle Biopsy
To reduce the burden to participants, open muscle biopsies are only being conducted in the 
minimum number of participants required. This procedure will be performed in Year 1, only 
on approximately 15 study participants (with the potential to collect a maximum of 33 if 
needed) randomized into Cohorts 1 and 2 from sites that have been trained and certified by 
the Sponsor/Sponsor designee to collect open muscle biopsies. The open muscle biopsies will 
be taken only at Baseline (Visit 2) and twice post-Baseline, on Day 360 (Visit 19) and on 
Day 1830 (Visit 41), to assess the distribution and amount of mini-dystrophin expression. As 
with any surgical procedure, complications can occur. These may include bruising, 
discomfort, bleeding, infection, and/or scarring at the biopsy site. The procedure may be 
performed under general anesthesia, which has unique risks in the setting of DMD. Although 
these risks are rare, it is expected that an anesthesiologist with experience treating patients 
with DMD is involved.
2.3.3.3. Immunity to AAV9
Following administration of fordadistrogene movaparvovec, immunity to AAV9 will be 
induced. As a result, it will not be possible for a participant treated with fordadistrogene 
movaparvovec to receive an additional dose of fordadistrogene movaparvovec or any other 
therapy that utilizes AAV9. Antibodies to AAV9 might also react to other serotypes of AAV 
and thus prevent treatment with therapies using these other vectors. At this time, there is no 
known means to mitigate this risk. 
2.3.3.4. Participation in Future Clinical Studies
Given the likelihood that the mini-dystrophin gene will persist within cardiac and skeletal 
muscle for many years (ie, no known wash-out period), it is possible that a participant in 
Study C3391003 may not be eligible for future studies of other therapies. 
2.3.3.5. Human Albumin
Human albumin, at a final concentration of 1.25%, will be used to prepare the IP solution. 
Risks associated with the use of human albumin include 1) hypersensitivity reactions that 
may progress to anaphylactic reactions and 2) the transmission of infectious diseases, such as 
viruses and theoretically, the Creutzfeldt-Jakob disease agent. For more information, please 
see prescribing information.50
2.3.3.6. Sorbitol
Each intravenous infusion of fordadistrogene movaparvovec (and infusion of placebo) 
contains 5% sorbitol, which is equivalent to 5 mg/mL or 150 mg/kg. Sorbitol is metabolized 
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into fructose, and products containing sorbitol given intravenously may have life-threatening 
effects in individuals with hereditary fructose intolerance (HFI) and should not be 
administered in this population. Although HFI is typically diagnosed in infancy, there can be 
children or adults with HFI who remain undiagnosed due to dietary management of 
symptoms. Symptoms suggestive of HFI include nausea, vomiting, bloating, stomach 
cramps, or diarrhea following the ingestion of foods or drinks containing fructose, or a 
pattern of avoiding sweet foods or drinks.
2.3.3.7. Gadolinium
A known adverse health effect related to gadolinium retention is a rare condition called 
nephrogenic systemic fibrosis that can occur in a small subgroup of patients with pre-existing 
renal failure. Sites will be responsible for confirming participant eligibility to undergo 
cardiac MRI scanning and gadolinium contrast administration.
3. OBJECTIVES, ESTIMANDS, AND ENDPOINTS
3.1. Efficacy Objectives, Estimands, and Endpoints
Objectives
Endpoints
Estimands
Primary:
Primary:
Primary:
To demonstrate superior efficacy of 
treatment with fordadistrogene 
movaparvovec as compared to placebo 
based on change from Baseline in the 
North Star Ambulatory Assessment 
(NSAA).
Change from Baseline at Week 52 in the 
NSAA total score.
Primary Estimand: 
Population: Boys with a 
genetic diagnosis of DMD 
who are ambulatory and age 
≥4 to <8 years;
Variable: Change from 
Baseline at Week 52 in the 
NSAA total score;
Death or loss of ambulation 
are identified as potential 
intercurrent events.
Population-level summary: 
difference in mean changes 
from Baseline at Week 52 in 
the NSAA total score 
between fordadistrogene 
movaparvovec and placebo.
Secondary:
Secondary:
Secondary:
To quantify the mini-dystrophin 
expression level in the muscle of 
participants treated with 
fordadistrogene movaparvovec. 
Change from Baseline in percent normal 
mini-dystrophin expression level in biceps 
brachii muscle biopsies at Day 360 using 
an LCMS assay.
Secondary Estimands:
Population: Boys with a 
genetic diagnosis of DMD 
who are ambulatory and age 
≥4 to <8 years;
Variable: Each secondary 
endpoint;
To characterize the distribution of 
mini-dystrophin expression in the 
muscle of participants treated with 
fordadistrogene movaparvovec.
Change from Baseline in percent of muscle 
fibers expressing mini-dystrophin in 
biceps brachii muscle biopsies at Day 360 
as assessed by immunofluorescence.
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Objectives
Endpoints
Estimands
To characterize the change in serum 
creatine kinase (CK) concentration in 
participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in 
serum CK concentration.
Death or loss of ambulation 
are identified as potential 
intercurrent events.
Population-level summary: 
difference in means between 
fordadistrogene 
movaparvovec and placebo 
for each secondary endpoint.
To characterize the skills gained, based 
on the individual items of the NSAA, 
in participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Number of skills gained at Week 52 based 
on the individual items of the NSAA.
To characterize the skills either 
improved or maintained, based on the 
individual items of the NSAA, in 
participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Number of skills either improved or 
maintained at Week 52 based on the 
individual items of the NSAA.
To characterize the 10-meter run/walk 
velocity in participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in the 
10 meter run/walk velocity.
To characterize the rise from floor 
velocity in participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in the 
rise from floor velocity.
To characterize the functional health 
status in participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in the 
Modified Pediatric Outcomes Data 
Collection Instrument (PODCI): Transfer 
and Basic Mobility Core Scale (Pediatric 
Parent).
Change from Baseline at Week 52 in the 
Modified PODCI: Sports and Physical 
Functioning Core Scale (Pediatric Parent).
Tertiary/Exploratory:
Tertiary/Exploratory:
To assess the systemic immune 
response (humoral and cellular) to 
mini-dystrophin in participants treated 
with fordadistrogene movaparvovec.
Immune response (eg, anti-drug antibodies 
(ADA) and enzyme-linked immune 
absorbent spot (ELISpot) to mini-
dystrophin through Year 1 Week 52.
N/A
To assess the systemic immune 
response (humoral and cellular) to the 
AAV9 capsid in participants treated 
with fordadistrogene movaparvovec.
Immune response (eg, ADA, ELISpot, 
and, NAb) to AAV9 through Year 1 Week 
52.
N/A
To characterize the change in ankle 
range of motion in participants treated 
with fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in 
passive ankle range of motion 
(dorsiflexion).
N/A
To characterize real-life function in 
participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in real-
life function parameters as assessed by 
actigraphy.
N/A
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Objectives
Endpoints
Estimands
To tabulate loss of ambulation in 
participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Loss of ambulation through Week 52.
N/A
To characterize pulmonary function in 
participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Change from Baseline at Week 52 in 
%pFVC.
N/A
To characterize health-related quality 
of life in participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Response to each of the 5 dimensions of 
the EQ-5D-Y proxy assessment at Week 
52.
N/A
Change from Baseline at Week 52 on the 
EQ visual analog scale (VAS) proxy 
assessment.
N/A
To characterize caregiver 
health-related QoL in caregivers of 
participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Response to each of the 5 dimensions of 
the EQ-5D-5L assessment at Week 52.
N/A
Change from baseline at Week 52 in the 
EQ-5D-5L VAS assessment.
N/A
Change from baseline at Week 52 in the 
EQ-5D-5L index score.
N/A
To evaluate viral vector shedding 
following a single administration of 
fordadistrogene movaparvovec.
Quantification of viral vector shedding 
kinetics of fordadistrogene movaparvovec 
in whole blood, saliva and urine.
N/A
To evaluate the efficacy of treatment 
with fordadistrogene movaparvovec in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec, based 
on change in the NSAA.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in the NSAA total score.
N/A
To characterize the change in serum 
CK concentration in participants in 
Cohort 2 after receiving 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in serum CK concentration.
N/A
To characterize the skills gained, based 
on the individual items of the NSAA, 
in participants in Cohort 2 after 
receiving fordadistrogene 
movaparvovec.
Number of skills gained from 
pre-fordadistrogene movaparvovec 
baseline to Year 2 Week 52 based on the 
individual items of the NSAA.
N/A
To characterize the skills either 
improved or maintained, based on the 
individual items of the NSAA, in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Number of skills either improved or 
maintained from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
based on the individual items of the 
NSAA.
N/A
To characterize the 10-meter run/walk 
velocity in participants in Cohort 2 
after receiving fordadistrogene 
movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in the 10 meter run/walk velocity.
N/A
To characterize the rise from floor 
velocity in participants in Cohort 2 
after receiving fordadistrogene 
movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in the rise from floor velocity.
N/A
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Objectives
Endpoints
Estimands
To characterize the functional health 
status in participants in Cohort 2 after 
receiving fordadistrogene 
movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in the Modified PODCI: Transfer and 
Basic Mobility Core Scale (Pediatric 
Parent).
N/A
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in the Modified PODCI: Sports and 
Physical Functioning Core Scale (Pediatric 
Parent).
N/A
To assess the systemic immune 
response (humoral and cellular) to 
mini-dystrophin and to AAV9 in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Immune response (eg, ADA to mini-
dystrophin and ELISpot to mini-
dystrophin) after Year 2 Day 1 IP 
administration through Year 2 Week 52.
N/A
To assess the systemic immune 
response (humoral and cellular) to 
mini-dystrophin and to AAV9 in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Immune response (eg, ADA, ELISpot, and 
NAb) to AAV9 through Year 2 Week 52.
N/A
To characterize the change in ankle 
range of motion in participants in 
Cohort 2 after receiving 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in passive ankle range of motion 
(dorsiflexion).
N/A
To characterize real-life function in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in real-life function parameters as assessed 
by actigraphy.
N/A
To tabulate loss of ambulation in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Loss of ambulation from 
pre-fordadistrogene movaparvovec 
baseline through Year 2 Week 52.
N/A
To characterize pulmonary function in 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
in %pFVC.
N/A
To characterize health-related quality 
of life in participants in Cohort 2 after 
receiving fordadistrogene 
movaparvovec.
Response to each of the 5 dimensions of 
the EQ-5D-Y proxy assessment at Year 2 
Week 52.
N/A
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
on the EQ visual analog scale (VAS) 
proxy assessment.
N/A
To characterize caregiver 
health-related QoL in caregivers of 
participants in Cohort 2 after receiving 
fordadistrogene movaparvovec.
Response to each of the 5 dimensions of 
the EQ-5D-5L assessment at Year 2 Week 
52.
N/A
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
on the EQ-5D-5L VAS assessment.
N/A
Change from pre-fordadistrogene 
movaparvovec baseline to Year 2 Week 52 
on the EQ-5D-5L index score.
N/A
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Objectives
Endpoints
Estimands
To characterize the long-term efficacy 
of treatment with fordadistrogene 
movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in the NSAA total score.
N/A
To quantify the long-term mini-
dystrophin expression level in the 
muscle of participants treated with 
fordadistrogene movaparvovec. 
Change from Baseline in percent normal 
mini-dystrophin expression level in biceps 
brachii muscle biopsies at Day 1830 (ie, 4 
or 5 years post fordadistrogene 
movaparvovec administration) using an 
LC-MS assay.
N/A
To characterize the long-term 
distribution of mini-dystrophin 
expression in the muscle of 
participants treated with 
fordadistrogene movaparvovec.
Change from Baseline in percent of muscle 
fibers expressing mini-dystrophin in 
biceps brachii muscle biopsies at 
Day 1830 (ie, 4 or 5 years post 
fordadistrogene movaparvovec 
administration) as assessed by 
immunofluorescence.
N/A
To characterize the long-term skills 
gained, based on the individual items 
of the NSAA, in participants treated 
with fordadistrogene movaparvovec.
Number of skills gained from pre-
fordadistrogene movaparvovec baseline to 
1, 2, 3, 4, and 5 years post fordadistrogene 
movaparvovec administration based on the 
individual items of the NSAA.
N/A
To characterize the long-term skills 
either improved or maintained, based 
on the individual items of the NSAA, 
in participants treated with 
fordadistrogene movaparvovec.
Number of skills either improved or 
maintained from pre-fordadistrogene 
movaparvovec baseline to 1, 2, 3, 4, and 5 
years post fordadistrogene movaparvovec 
administration based on the individual 
items of the NSAA.
N/A
To characterize the long-term 10-meter 
run/walk velocity in participants 
treated with fordadistrogene 
movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in the 10 meter run/walk 
velocity.
N/A
To characterize the long-term rise from 
floor velocity in participants treated 
with fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in the rise from floor 
velocity.
N/A
To characterize the long-term 
functional health status in participants 
treated with fordadistrogene 
movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in the Modified PODCI: 
Transfer and Basic Mobility Core Scale 
(Pediatric Parent).
N/A
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in the Modified PODCI: 
Sports and Physical Functioning Core 
Scale (Pediatric Parent).
N/A
Observed scores post fordadistrogene 
movaparvovec administration in the 
N/A
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Objectives
Endpoints
Estimands
Modified PODCI: Transfer and Basic 
Mobility Core Scale (Adolescent).
Observed scores post fordadistrogene 
movaparvovec administration in the 
Modified PODCI: Sports and Physical 
Functioning Core Scale (Adolescent).
N/A
To characterize the long-term systemic 
immune response (humoral and 
cellular) to mini-dystrophin and to 
AAV9 in participants treated with 
fordadistrogene movaparvovec.
Immune response (eg, ADA to mini-
dystrophin and ELISpot to mini-
dystrophin) at 1, 2, 3, 4 and 5 years post 
fordadistrogene movaparvovec 
administration.
N/A
To characterize the long-term systemic 
immune response (humoral and 
cellular) to mini-dystrophin and to 
AAV9 in participants treated with 
fordadistrogene movaparvovec.
Immune response (eg, ADA, ELISpot, and 
NAb) to AAV9 at 1, 2, 3, 4 and 5 years 
post fordadistrogene movaparvovec 
administration.
N/A
To characterize long-term range of 
motion in participants treated with 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in passive ankle range of 
motion (dorsiflexion).
N/A
To characterize long-term real-life 
function in participants treated with 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in real-life function as 
assessed by actigraphy.
N/A
To characterize time to loss of 
ambulation in participants treated with 
fordadistrogene movaparvovec.
Time in years to loss of ambulation.
N/A
To characterize long-term respiratory 
function in participants treated with 
fordadistrogene movaparvovec.
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 5 
years post fordadistrogene movaparvovec 
administration in %pFVC.
N/A
Peak FVC post fordadistrogene 
movaparvovec administration.
N/A
To characterize the long-term health-
related quality of life in participants 
treated with fordadistrogene 
movaparvovec.
Response to each of the 5 dimensions post 
fordadistrogene movaparvovec in the EQ-
5D-Y (proxy). 
N/A
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 
5 years post fordadistrogene 
movaparvovec administration in the EQ 
VAS (proxy).
N/A
Response to each of the 5 dimensions post 
fordadistrogene movaparvovec 
administration in the EQ-5D-Y (self-
report).
N/A
Observed EQ VAS post fordadistrogene 
movaparvovec administration (self-report).
N/A
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Objectives
Endpoints
Estimands
To characterize the long-term caregiver 
health-related quality of life in 
caregivers of participants treated with 
fordadistrogene movaparvovec as 
compared to placebo.
Response to each of the 5 dimensions of 
the EQ-5D-5L assessment at 
pre-fordadistrogene movaparvovec 
baseline and at 1, 2, 3, 4 and 5 years post 
fordadistrogene movaparvovec.
N/A
Change from pre-fordadistrogene 
movaparvovec baseline at 1, 2, 3, 4 and 
5 years post fordadistrogene 
movaparvovec administration in the EQ-
5D-5L VAS.
N/A
Change from pre-fordadistrogene 
movaparvovec baseline at all timepoints 
after fordadistrogene movaparvovec 
administration in the EQ-5D-5L index 
score.
N/A
To characterize the long-term health 
resource utilization in participants 
treated with fordadistrogene 
movaparvovec.
Health Resource Utilization (HRU:CG) 
survey responses at Baseline and at Years 
1, 2, 3, 4, and 5 post fordadistrogene 
movaparvovec administration.
N/A
To characterize the long-term caregiver 
lost work productivity and activity 
impairment for caregivers of 
participants treated with 
fordadistrogene movaparvovec.
WPAI:DMD Caregiver responses 
(including absenteeism, presenteeism, 
work productivity loss, and activity 
impairment) at Baseline and at Years 2, 3, 
4, and 5 post fordadistrogene 
movaparvovec administration.
N/A
To enable exploratory research through 
collection of banked biospecimens, 
unless prohibited by local regulations 
or ethics committee decision.
Potential results from exploratory analysis 
of banked biospecimens (these results may 
or may not be generated in the context of 
the present study).
N/A
3.2. Safety Objectives and Endpoints
Objectives
Endpoints
To characterize the safety of treatment 
with fordadistrogene movaparvovec as 
compared to placebo.
Incidence, severity and causal relationship of treatment-
emergent AEs (TEAEs) (AEs and SAEs) through Week 52.
Incidence of abnormal laboratory findings and magnitude of 
change through Week 52.
Abnormal and clinically relevant changes through Week 52 in:

Physical exam;

Neurologic exam;

Weight;

Vital signs;

ECG;

Echocardiogram;

Cardiac MRI

Child Behavior Check List (CBCL).
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Objectives
Endpoints
To characterize the safety of treatment 
with fordadistrogene movaparvovec in 
participants in Cohort 2.
Incidence, severity and causal relationship of TEAEs (AEs and 
SAEs) after fordadistrogene movaparvovec administration 
through Year 2 Week 52.
Incidence of abnormal laboratory findings and magnitude of 
change from pre-fordadistrogene movaparvovec baseline 
through Year 2 Week 52.
Abnormal and clinically relevant changes from pre-
fordadistrogene movaparvovec baseline through Year 2 Week 52 
in:

Physical exam;

Neurologic exam;

Weight;

Vital signs;

ECG;

Echocardiogram;

Cardiac MRI

CBCL.
To characterize the long-term safety of 
treatment with fordadistrogene 
movaparvovec.
Incidence, severity and causal relationship of TEAEs (AEs and 
SAEs) through 5 years post fordadistrogene movaparvovec 
administration.
Incidence of abnormal laboratory findings and magnitude of 
change through 5 years post fordadistrogene movaparvovec 
administration.
Abnormal and clinically relevant changes through 5 years post 
fordadistrogene movaparvovec administration in:

Physical exam;

Neurologic exam;

Weight;

Vital signs;

ECG;

Echocardiogram;

Cardiac MRI

CBCL.
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4. STUDY DESIGN
4.1. Overall Design
This is a Phase 3, global, multi-center, randomized, double-blind, placebo-controlled study to 
assess the safety and efficacy of fordadistrogene movaparvovec gene therapy in 
approximately 99 ambulatory male participants (in the FAS; see Section 9.3), ages ≥4 to <8 
years, with a genetic diagnosis of DMD who are on a stable daily regimen of glucocorticoids. 
Eligible participants will be randomized into Cohort 1 or Cohort 2 in a 2:1 fashion and 
stratified by their age at Screening (<6 or ≥6 years old). Study enrollment will be managed to 
ensure that no more than approximately 55% of dosed participants are in either of the 
Screening age strata. Enrollment will be assessed periodically, and if an imbalance is noted, 
enrollment of the overrepresented stratum may be paused until a more balanced distribution 
is achieved. In the context of this study, treatment will consist of two single intravenous 
infusions, one of fordadistrogene movaparvovec and one of placebo, with the timing and 
sequence as described below:

Cohort 1 (approximately 66 participants): will receive a single dose of 
fordadistrogene movaparvovec on Day 1 (Visit 3) and a single dose of placebo at Day 
390 (Visit 20). They will be followed for 5 years after the administration of the single 
dose of fordadistrogene movaparvovec. Total time on study will be approximately 5 
years. 

Cohort 2 (approximately 33 participants): will receive a single dose of placebo on 
Day 1 (Visit 3) and a single dose of fordadistrogene movaparvovec at Day 390 (Visit 
20), if they remain eligible. They will be followed for 5 years after the administration 
of the single dose of fordadistrogene movaparvovec. Total time on study will be 
approximately 6 years.
In order to ensure an adequate understanding and management of potential safety risks, the 
initial rate of randomization into the study will be limited. No more than 2 participants per 
week will be randomized at the start of the study, until 4 participants have been observed for 
at least 2 weeks post-IP administration. After that, the rate could be increased to no more 
than 3 participants randomized per week (until at total of 10 participants have been observed 
for at least 2 weeks post-IP administration). Thereafter, the rate of randomization could be 
further increased to no more than 5 participants randomized per week (until a total of 
20 participants have been observed for at least 2 weeks post-IP administration). After this 
time, no limits to the randomization rate will be imposed unless the study team, in 
consultation with the E-DMC, determines otherwise. Ongoing blinded review of safety data 
will be conducted by the study team, and frequent periodic unblinded reviews of safety data 
will be conducted by the E-DMC, as described in detail in the E-DMC charter (see 
Section 9.5.1). 
Table 1 provides a brief overview of the study periods; for full details please see SoA.
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Table 1.
Brief Overview of the Study Periods
Study Period
Days and Visits
Overview of Main Tests/Procedures
Study Eligibility 
Assessment
Screening (Visit 1)
Inclusion and Exclusion criteria review.
Baseline (Visit 2)
Inclusion and Exclusion criteria review, including 
NAb results;
Efficacy assessments;
Muscle biopsy;*
Obtain weight measurement;
Randomization and request IP.
IP Administration
Day 1 (Visit 3)
Pre-dose Inclusion and Exclusion criteria review, 
including NAb results;
Year 1 IP administration;
Post IP safety monitoring
Day 2 (Visit 4) to
Day 34 (Visit 13)
Post-dose safety monitoring;
Viral vector shedding.
Completion of Year 1
Day 60 (Visit 14) to
Day 360 (Visit 19)
Routine safety monitoring;
Efficacy assessments;
Muscle biopsy (Day 360);*
Obtain weight measurement (Visit 18);**
Request IP on Day 328 (Visit 18);
Viral vector shedding.
Eligibility Assessment for 
Year 2 IP Administration 
Day 360 (Visit 19)
Assess eligibility for Year 2 IP administration, 
including NAb results.
Viral vector shedding.
IP Administration
Day 390 (Visit 20)
Pre-dose review of eligibility for Year 2 IP 
administration, including NAb results;
Year 2 IP administration.
Post IP safety monitoring
Day 391 (Visit 21) to 
Day 423 (Visit 30)
Post-dose safety monitoring;
Viral vector shedding.
Completion of Year 2 
Day 449 (Visit 31) to 
Day 749 (Visit 35)
Routine safety monitoring;
Efficacy assessments;
Viral vector shedding.
Long-Term Follow-up
Year 3 to Year 6
Day 930 (Visit 36) to 
Day 2190 (Visit 43)
Routine safety monitoring;
Efficacy assessments;
Viral vector shedding;
Muscle biopsy (Day 1830).* 
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Table 1.
Brief Overview of the Study Periods
Study Period
Days and Visits
Overview of Main Tests/Procedures
* First ~15 participants (with the potential to collect a maximum of 33 if needed) from selected sites. The 
post-Baseline muscle biopsies will be performed on Day 360 and Day 1830. 
** For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be 
shipped to the site will be determined once the study has been restarted. Therefore, the weight collected at 
Day 328 (Visit 18) will not be entered into the interactive response technology drug management system 
during the study dosing pause. Participants will be evaluated for Year 2 IP eligibility when the study is 
restarted.
The primary analysis will occur after at least 90 FAS participants complete Day 360 (Visit 
19) or discontinued from the study prior to Week 52 if they had received Year 1 IP at least 
one year prior to the data cutoff. After the database has been released for the primary 
analysis, the study may become fully unblinded. 
Investigators in Japan should see Section 10.10 (Appendix 10) for details on the interval 
between IP administration for consecutive participants.
4.2. Scientific Rationale for Study Design
4.2.1. Rationale for Inclusion of a Placebo Control Group
The purpose of this Phase 3 study is to evaluate the safety and efficacy of a single IV 
administration of fordadistrogene movaparvovec compared to placebo in participants with 
DMD. The results of this study will be used to support submission for registration of this 
therapy for treatment of DMD. There are several reasons that a placebo-controlled design is 
necessary to generate robust results. First, there is considerable variability in the disease 
progression and therefore improved function among treated participants can be attributed to 
fordadistrogene movaparvovec only when compared to participants randomized to placebo. 
Second, in the age range of the study population, some young participants may be improving 
their motor function as a result of ongoing development and the only way to differentiate this 
improvement from that which may occur as a result of fordadistrogene movaparvovec is by 
comparison to a placebo group. Third, there are not adequate data on the impact of small 
changes in glucocorticoid regimen, as are allowed in this study, to differentiate this effect 
from that of fordadistrogene movaparvovec. Ensuring that the study remains blinded through 
the primary analysis is important because knowledge of treatment assignment can bias
performance and evaluation of functional assessments. 
Those randomized to Cohort 2 will receive fordadistrogene movaparvovec after completing 
the first year of observation, provided they remain eligible. This will enable all eligible 
participants to receive treatment with fordadistrogene movaparvovec.
4.2.2. Rationale for Selected Participant Population
The selected population includes participants with a genetic diagnosis of DMD who are 
ambulatory and age ≥4 to <8 years. There are two observations underlying the rationale for 
this age range. 
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The first, which defines the upper age limit, is based on the pathophysiology of DMD and the 
mechanism of action of fordadistrogene movaparvovec. Lack of functional dystrophin leads 
to damage of the sarcolemma upon repeated muscle contraction. This initially causes 
inflammation followed by cell death with replacement of muscle by fibrosis and fat. The goal 
of gene therapy is to provide mini-dystrophin to skeletal and cardiac muscle such that it 
replaces the missing or dysfunctional endogenous dystrophin and acts to protect muscle, 
thereby significantly reducing the inflammatory and fibrotic processes. Muscles that have 
already progressed to cell death and fibrosis are not expected to be affected by therapy. Thus, 
it is anticipated that maximum benefit will occur for patients in whom there is minimal 
irreversible muscle damage. Imaging studies have revealed that some inflammation and 
fibrosis occurs in select lower limb muscles in patients as early as age 2 years (Li et al., 
2015).51 While most lower limb muscles have fatty infiltration by age 7 years, with the 
severity of fatty infiltration increasing rapidly after this age, different patients of the same 
age have varying degrees of fatty infiltration of the thigh muscles, ranging from mild to 
severe (Li et al, 2015).51 These imaging findings correspond to the average pace of clinical 
disease progression in which initial symptoms often present at age 2 years, improvement in 
ambulatory motor function occurs as a result of development through age 5 years, a plateau 
in function persists through age 7 years, and then decline occurs until loss of ambulation at 
approximately age 12 years (Ciafaloni et al., 2009; Bushby & Connor, 2011; McDonald et 
al., 2013; Mercuri et al., 2016).52,53,54,55 In order to minimize clinical heterogeneity and to 
treat boys prior to their anticipated functional decline, the designated age range for this trial 
has a maximum of <8 years old . However, as there is broad variability in DMD disease 
progression, and disease milestones will not occur at the same ages for all patients, there is 
the potential for treatment benefit outside of the age range included in the trial (Zambon et al, 
2022; Bello et al, 2016)56, 57. 
The second observation, which defines the lower age limit, is based on the ability of the 
NSAA to reflect motor function across a range of ages. This endpoint was initially validated 
for DMD patients age ≥4 years [Mayhew et al., 2013; Scott et al., 2012; Mazzone et al., 
2009].58,59,60 There have been reports of the NSAA being used in patients as young as 3 years 
of age (DeSanctis et al., 2013; Mercuri et al. 2016).61,55 However, it has been shown that 
typically developing boys cannot perform all the items until age 4 years (Mercuri et al., 
2016),55 and thus the full scale could not be used in boys below age 4 years. Furthermore, the 
development of motor skills prior to age 4 years in DMD boys can be affected by cognitive 
aspects of the disease that are not the target of therapy with fordadistrogene movaparvovec. 
Therefore, NSAA as a primary efficacy endpoint in this study is most appropriate with a 
population age ≥4 years.
4.2.3. Rationale for Selecting NSAA for the Primary Endpoint
There are multiple aspects of the NSAA that make it suitable as a primary efficacy endpoint 
in the ambulatory DMD population. First, it is a validated measure developed specifically for 
the DMD population in order to precisely monitor disease progression and the impact of 
potential treatments (Scott et al., 2012).59 Second, substantial natural history collected over 
several different studies has revealed that it is sensitive enough to capture change in disease 
state over a one year period, and that the variability in this change is relatively small, such 
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that a study of reasonable sample size can be performed. By contrast, other measures used in 
the clinical trial setting to evaluate ambulatory DMD patients, such as the Six Minute Walk 
Test and the Four Stair climb, have been shown to have less change over one year and higher 
variability. Third, NSAA is capable of differentiating function in DMD patients from that in 
normally developing boys over the entire age range of this study (DeSanctis et al., 
2015; Mercuri et al., 2016),61,55 which is not the case with other measures of ambulatory 
function, such as the 10 meter run/walk and the Six Minute Walk Test. This aspect of the 
NSAA provides the potential to capture improvement in function (rather than simply 
stability) that may occur as a result of treatment. Finally, since the NSAA is comprised of 
several activities required for daily living, such as rising from the floor, standing, walking, 
and rising up onto a step, it is a comprehensive evaluation that best reflects the ability of boys 
to function in their daily lives. As such, it aligns with the potential value of therapy for 
patients and their caregivers, and with the interest of regulatory agencies to evaluate 
treatments utilizing endpoints that reveal the impact of therapy on daily living.
4.2.4. Rationale for Collection of Muscle Biopsies
This study includes open muscle biopsy procedures for approximately 15 study participants 
(with the potential to collect a maximum of 33 if needed) at three time points: at Baseline 
(Visit 2) and post-Baseline at Day 360 (Visit 19) and at Day 1830 (Visit 41). These biopsies 
will enable an assessment of the change from Baseline in the percent normal mini-dystrophin 
protein expression level and of the percent of muscle fibers expressing mini-dystrophin. 
Results of these analyses are important for 2 reasons. First, data on the expression and 
distribution of mini-dystrophin in skeletal muscle could enable a more thorough 
understanding of the elements contributing to the effects of treatment on function. Second, a 
demonstration in this study that mini-dystrophin expression is reasonably likely to predict 
clinical benefit could enable the use of this biomarker to support evidence of efficacy in other 
DMD populations in which functional endpoints are not as established.
4.2.5. Rationale for Collection of Banked Biospecimens
Banked biospecimens will be collected for exploratory pharmacogenomic, genomic, and/or 
biomarker analyses and retained in the Biospecimen Banking System (BBS), which makes it 
possible to better understand the IP’s mechanism of action and to seek explanations for 
differences in, for example, exposure, tolerability, safety, and/or efficacy not anticipated 
prior to the beginning of the study.
4.3. Justification for Dose
At the initiation of the clinical program, 2 potentially safe and effective doses were identified 
through pre-clinical studies: 1E14 vg/kg and 3E14 vg/kg. The rat dose-finding study 
indicated that the minimal effective dose was 1E14 vg/kg wherein there was efficient muscle 
transduction and efficacy. The dose of 3E14 vg/kg was determined to be the NOAEL in a 
juvenile rat toxicology study and was associated with increased transduction and dystrophin 
expression in cardiac and skeletal muscles in the rat dose-finding study. The DMD rat model 
showed efficacy at both of these dose levels, with improvement of the tissue architecture of 
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skeletal muscles and heart, improved muscle strength and endurance, and improvement of the 
cardiac diastolic function. 
As of 20 May 2019, the biceps brachii muscle biopsies in 3 participants in each of the low 
and high dose cohorts in Study C3391001 at Baseline and 2 months post-treatment have been 
evaluated for percent normal mini-dystrophin expression level and percent of muscle fibers 
expressing mini-dystrophin. The preliminary results provide evidence of transduction. Since 
the degree of functional benefit produced by specific mini-dystrophin expression levels is 
unknown, it was determined that using 3E14 vg/kg to enable a higher degree of 
mini-dystrophin expression would be most likely to produce the greatest clinical benefit. In 
addition, the safety profile of 3E14 vg/kg, as understood through the exposures in the 
Phase 1b study to date, appears to be adequate to support the benefit:risk of this dose. 
The assay used to determine the dose for the Phase 1b study was based on the detection of 
the inverted terminal repeats (ITR) within the DNA sequence. The assay used to determine 
the dose for the Phase 3 study is based on the detection of the transgene (TG) DNA sequence, 
in accordance with regulatory requirements. The numerical results of these assays differ 
slightly such that a dose of 3E14 using the ITR method is approximately equivalent to a dose 
of 2E14 with the TG method. Therefore, the dose selected for Study C3391003, identified as 
2E14, is approximately equivalent to the highest dose of 3E14 used in Study C3391001. 
4.4. End of Study Definition
A participant is considered to have completed the study if he has completed all periods of the 
study including the last visit shown in the Schedule of Activities. 
The end of the study is defined as the date of the last visit of the last participant in the study. 
5. STUDY POPULATION
This study can fulfill its objectives only if appropriate participants are enrolled. The 
following eligibility criteria are designed to select participants for whom participation in the 
study is considered appropriate. All relevant medical and nonmedical conditions should be 
taken into consideration when deciding whether a particular participant is suitable for this 
protocol. 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also 
known as protocol waivers or exemptions, is not permitted.
5.1. Inclusion Criteria
Participants are eligible to be included in the study only if all of the following criteria apply:
1. Male participants who are ≥4 and <8 years of age at Screening (Visit 1).
2. Confirmed diagnosis of DMD by prior genetic testing demonstrating the presence of a 
mutation in the dystrophin gene consistent with DMD at Screening (Visit 1). If the 
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Investigator determines that the results are inconclusive, a repeat genetic testing will 
be allowed through the central laboratory at Screening (Visit 1).
3. Receipt of a stable daily dose of glucocorticoids (≥0.5 mg/kg/day prednisone, 
prednisolone, or ≥0.75 mg/kg/day deflazacort) for at least 3 months prior to Screening 
(Visit 1) and during the period between Screening (Visit 1) and Day 1 (Visit 3). In 
order to comply with protocol procedures, there should also be a reasonable 
expectation that this daily dose of glucocorticoids will remain stable for the first 
2 years of the study. A stable dose is defined as one in which any change is 
≤0.2 mg/kg (See Section 6.5.1 for detailed requirements).
4. A NSAA total score >16 and <30 at Screening (Visit 1).
5. Ambulatory, defined as being able to walk 10 meters unassisted, at Screening 
(Visit 1).
6. Participants/legally acceptable representatives who are willing and able to comply 
with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and 
other study procedures including, potentially, open muscle biopsies under general 
anesthesia and cardiac MRI under general anesthesia.
7. Participants/legally acceptable representatives who are capable of giving 
assent/signed informed consent as described in Appendix 1, which includes 
compliance with the requirements and restrictions listed in the assent/informed 
consent document (ICD) and in this protocol.
8. Participants/legally acceptable representatives who are willing to protect the integrity 
of the study data by not actively seeking sensitive clinical data (eg, CK, ALT, AST, 
NAb to AAV9) through independent laboratory tests and by not sharing trial 
experiences with other participants or publicly (eg, through social media).
5.2. Exclusion Criteria
Participants are excluded from the study if any of the following criteria apply:
1. Prior treatment with gene therapy, defined as any therapy introducing exogenous 
DNA or intended to permanently alter the endogenous DNA. Gene therapy (other 
than IP) will be prohibited for the duration of the study.
2. Exposure within 6 months prior to Screening (Visit 1) to any treatment designed to 
increase dystrophin expression (including, but not limited to exon-skipping and 
nonsense read-through). These treatments will also be prohibited during the period 
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between Screening (Visit 1) and Day 1 (Visit 3) and for the first 52 weeks of the 
study. Please note that for participants who are eligible for these treatments:
Participants may be enrolled who have previously experienced lack of efficacy, or
intolerance, as long as they received their last dose more than 6 months before 
screening (Visit 1), or who have refused these treatments.
Participants receiving these treatments from which there is believed to be benefit 
should not discontinue them in order to meet this exclusion criterion and enroll in 
the study.
3. Previous administration with an investigational drug or investigational vaccine within 
30 days (or as determined by the local requirement) or 5 half-lives (whichever is 
longer) at Screening (Visit 1). These treatments will also be prohibited during the 
period between Screening (Visit 1) and Day 1 (Visit 3) and for the first 2 years of the 
study.
4. Known cognitive impairment or behavioral issues that would impede the ability to 
follow instructions, in the judgment of the Investigator, at Screening (Visit 1).
5. Any nonhealed injury at Screening (Visit 1) which, in the opinion of the Investigator, 
may impact functional testing; additionally, lower limb fractures must have been 
healed for at least 3 months prior to Screening (Visit 1).
6. Positive test for NAb to AAV9, based on the threshold determined by the Central 
Laboratory, from a sample taken at Screening (Visit 1). 
7. Receipt of a live attenuated vaccination within 30 days prior to Screening (Visit 1).
Receipt of a live attenuated vaccination will also be prohibited for 90 days before Day 
1 (Visit 3), for 90 days prior to Year 2 IP administration, and for the first 2 months 
after each IP administration.
8. Abnormality in hematology or chemistry profiles at Screening (Visit 1). A single 
repeat for value(s) outside allowable limits is permitted to re-assess eligibility: 
a.
Absolute neutrophil count <1000 cells/mm3;
b. Platelets <150 x 103/µl;
c.
Cystatin C >1.2 x ULN;
d. Positive hepatitis A virus (anti-HAV) immunoglobulin M, hepatitis B surface 
antigen (HbsAg), and/or hepatitis C antibody (HCVAb);
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e.
Markers of hepatic inflammation or overt or occult cirrhosis as evidenced by one 
or more of the following:
1. Prothrombin time (PT) > upper limit of normal (ULN); prolonged 
international normalized ratio (INR) >ULN;
2. GLDH >2 x ULN;
3. Total bilirubin >1.5 x ULN (unless the participant has a history of Gilbert 
disease) and direct bilirubin >0.5 mg/dL;
4. Gamma-glutamyl transferase (GGT) >1.5 x ULN.
9. Other acute or chronic medical or psychiatric condition at Screening (Visit 1), 
including recent (within the past year) or active suicidal ideation or behavior (using 
screening by the Child Behavior Check List (CBCL) and determined by the 
Investigator, as described in Section 8.2.13) or laboratory abnormality that may 
increase the risk associated with study participation or IP administration or may 
interfere with the interpretation of study results and, in the judgment of the 
Investigator, would make the participant inappropriate for entry into this study.
10. Acute infection at Screening (Visit 1) or Baseline (Visit 2) that, in the judgement of 
the Investigator is not expected to be fully resolved at least 2 weeks before Day 1 
(Visit 3). At Day 1 (Visit 3), participants must have been infection-free for at least 
2 weeks prior to IP administration. Delay of IP administration for up to 14 days is 
permitted to enable infections to become fully resolved. 
11. Investigator site staff members directly involved in the conduct of the study and their 
family members, site staff members otherwise supervised by the Investigator, or 
Pfizer employees, including their family members, directly involved in the conduct of 
the study. 
12. Known hypersensitivity to any of the components of the IP or solution for infusion, 
such as hypersensitivity to albumin or a diagnosis of HFI. Symptoms suggestive of 
HFI include nausea, vomiting, bloating, stomach cramps, or diarrhea following the 
ingestion of sweet foods or drinks, or a pattern of avoiding sweet foods or drinks.
13. Contraindication to the use of eculizumab, as per the local prescribing information.
14. LVEF <50% on echocardiogram performed at the Screening Visit (Visit 1), as 
evaluated by the central reader.
15. Participants with the following genetic abnormalities in the dystrophin gene as 
confirmed by the investigator based on the review of DMD genetic testing:
a.
Any mutation (exon deletion, exon duplication, insertion, or point mutation) affecting 
any exon between exon 9 and exon 13, inclusive; OR
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b. A deletion that affects both exon 29 and exon 30; OR
c.
A deletion that affects any exons between 56-71, inclusive.
For details on the retrospective assessment of exclusion criterion 15, please see 
Appendix 12.
16. Cardiac pathologies, as evaluated by a pediatric cardiologist at the Screening Visit 
(Visit 1):
a.
Diagnosis of myocarditis (eg, viral): either based on prior medical history or based 
on findings in cardiac imaging tests;
b. Any other cardiac history, and/or condition and/or abnormalities in cardiac imaging, 
that determine that the participant should not be included in the study, as per the 
cardiologist.
17. Not a candidate for mechanical cardiac or respiratory support, or any other invasive 
intervention, if indicated for management of an acute event as determined by the 
cardiologist in consultation with the investigator at the Screening Visit (Visit 1). 
5.3. Management of Participants Post Enrollment and Dosing Pause
If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), the time between the Screening 
Visit (Visit 1) and the Day 1 Visit (Visit 3), or the time between Day 360 Visit (Visit 19) and 
Day 390 Visit (Visit 20) is more than 90 days, participants will undergo one or more 
unplanned visits to repeat tests and procedures, as applicable to re-confirm study/IP 
administration eligibility criteria.
5.3.1. Study and Year 1 IP Administration Eligibility
If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), the time between the Screening 
Visit (Visit 1) and the Day 1 Visit (Visit 3), is more than 90 days, participants will undergo 
an unplanned visit to repeat the following tests and procedures, as applicable, and will re-
confirm all study/IP administration eligibility criteria:

Full physical and neurological examination;

Vital signs;

Laboratory tests: clinical safety, chemistry and hepatic safety, cardiac troponin, INR, 
and hepatitis serology;

NAb to AAV9, if the previous sample was collected more than 55 days before the day 
of IP administration (see Section 6.1.1);
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
Functional assessments: NSAA, ambulatory status;

Echocardiogram and ECG;

Medical history, concomitant medications, and background glucocorticoid regimen 
assessment.

Weight: for participants who were already randomized but have not yet received IP, 
weight will be measured again following the process outlined in Section 8.2.3. The 
site will update the weight in the IRT system, to allow re-calculation of the dose of IP 
if needed, once study eligibility is re-confirmed. Participants with an increase or 
decrease in body weight of more than 5% will have the dose of IP re-calculated. 
If a participant has started or completed the Screening Visit (Visit 1), but was not yet 
randomized when the assessments are repeated, and he is found to be ineligible for study 
entry based on the results of repeated tests and procedures, he will be screen failed.
If a participant was already randomized, but had not yet received IP when the assessments 
are repeated, and he is found to be ineligible for study entry based on the results of the 
repeated tests and procedures, he will be withdrawn from the study.
For participants who completed the Baseline Visit (Visit 2) and were randomized, and who 
are re-confirmed to be eligible for study entry, a second unplanned visit will be scheduled to 
perform a NAb to AAV9 test if the Day 1 Visit (Visit 3) is expected to be more than 55 days 
after the collection of the previous sample.
5.3.2. Year 2 IP Administration Eligibility
If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), a participant’s Year 2 IP 
administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be 
delayed for that participant until the pause is lifted. Participants with delayed Year 2 IP 
administration will not receive the protocol-mandated glucocorticoid regimen until the pause 
is lifted and Year 2 IP administration takes place; they will remain on their background 
glucocorticoid regimen until then. If the pause is not lifted within 6 months of the Day 360 
(Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 
±7 days and approximately every 6 months afterwards until the pause is lifted (or more 
frequently if considered necessary by the investigator), for sites in Israel, see Appendix 16.
At this visit the following tests and assessments will be performed:

Full physical and neurological examination;

Vital signs;
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
Laboratory blood tests: clinical safety; chemistry and hepatic safety, troponin and 
CK;

Functional assessments: NSAA, ROM, and ambulatory status;

Echocardiogram and ECG.
Once the pause is lifted, participants who have attended Day 360 (Visit 19) more than 
90 days before will undergo another unplanned visit to assess eligibility for IP 
administration. This visit will require the same tests and procedures as the Day 360 (Visit 19) 
(see Section 1.3.1). Additionally, sites will enter the weight measured at this unplanned visit 
into the interactive response technology drug management system to calculate the dose of IP 
for Year 2 administration and to trigger IP shipment to the site.  Participants with an increase 
or decreased in body weight of more than 5% will have the dose of IP re-calculated
For participants who attended the prior unplanned visit for general monitoring within 90 days 
of the second unplanned visit to confirm eligibility for Year 2 IP administration, only the 
following laboratory tests will be performed:

NAb to AAV9

INR and hepatitis serology
For participants confirmed to be eligible for Year 2 IP administration by the unblinded 
medical monitor (see Section 7.1), Day 390 (Visit 20) should take place within 30 days of the 
unplanned visit. At this visit the investigator will review the additional Year 2 IP 
administration eligibility criteria (see Section 7.1) and confirm if the participant can receive 
IP. After Year 2 IP administration has taken place, participants will continue to follow the 
regular protocol Schedule of Activities; the days in study will be counted starting on the day 
of Year 2 IP administration.
5.4. Siblings
When ≥2 brothers meet all the study entry criteria, they will all be enrolled in the study 
simultaneously. One of the brothers will be defined as the “participant” and the other(s) will 
be defined as the “sibling(s)”. The sibling(s) will not be randomized but they will receive the 
same treatment with approximately the same timing (as long as the siblings were strictly 
separated from each other until both have received IP) and sequence based on the Cohort to 
which the participant is randomized. The sibling(s) will participate fully in the double blind 
study as a participant, complete all visits and evaluations, and comply with all protocol 
requirements. Data from the sibling(s) will not contribute to the analyses of the primary and 
secondary endpoints, and thus siblings will not be included within the approximately 
99 participants in the FAS (see Section 9.3) required to provide adequate power for the 
primary endpoint. Data from the sibling(s) will be included in a supplemental analysis of the 
primary endpoint, all analyses of safety, and in exploratory analyses of participants in 
Cohort 2 during the delayed treatment period (Change from pre fordadistrogene 
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movaparvovec Baseline to Year 2 Week 52) and of long-term efficacy (Change from pre 
fordadistrogene movaparvovec baseline at 1, 2, 3, 4 and 5 years post fordadistrogene 
movaparvovec administration).
If the participant is randomized within the first approximately 15 participants collecting 
muscle biopsies, muscle biopsies will be collected from him and his sibling(s), but sibling(s) 
will not contribute to the approximately 15 participants. Biopsy data from the sibling(s) will 
be excluded from analyses of mini-dystrophin in this study but will be included in 
supplemental analyses of mini-dystrophin endpoints. Because of this, it may be necessary to 
perform more than 15 muscle biopsies at each time point to accrue muscle biopsies from 
approximately 15 participants. 
The rationale for ensuring that the sibling(s) receives the same treatment as the participant is 
to minimize the risk that brothers are randomized to different cohorts and the one receiving 
placebo at Year 1 Day 1 develops NAb, due to close household contact with the one 
receiving fordadistrogene movaparvovec, and therefore cannot receive treatment at Year 2 
Day 1. 
5.5. Lifestyle Considerations
5.5.1. Activity
Participants should be instructed to continue with routine physical therapy including 
stretching and use of orthoses to prevent or minimize contractures or muscle deformities.
Participants will be instructed to maintain normal activity levels and avoid activities that are 
not part of their normal daily routine for 24 hours before study visits where functional 
assessments will be performed. 
5.5.2. Hydration
In general, participants are recommended to drink at least 1 liter of fluid per day to stay 
hydrated, particularly in the first month following each IP administration and prior to all 
study visits. 
In addition, for the first 34 days following each IP administration (or longer if deemed 
clinically necessary), participants should be monitored to determine if they pass urine at least 
once during a 12-hour period or if they have a significant change in urine output in less than 
24 hours. If fluid intake and/or urine output are observed to be less than these thresholds, 
then participants (and/or caregivers) should be instructed to promptly contact the site for a 
possible unscheduled visit and/or biospecimen collection.
5.5.3. Hygiene
It is suggested that the participant and those around him be reminded to practice good 
hygiene, especially for the month prior to and during the first 2 months after each IP 
administration, such as the following: (1) thoroughly washing hands with soap and water 
after using the bathroom, before preparing or touching food, or after blowing one’s nose, 
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coughing, sneezing, etc.; (2) limiting contact with persons who might be sick; and (3) not 
sharing glasses, dishes, utensils, or other items that touch the mouth.
Families and close contacts of the participant should be made aware of the potential risk for 
developing NAbs to AAV9 for at least the first 2 months after IP administration, which is 
especially relevant for any contact who might be a candidate for gene therapy. The risk can 
be reduced by avoiding contact with the participant´s bodily fluids (such as saliva, urine, and 
blood) during at least the first 2 months after IP administration.
5.6. Screen Failures
Screen failures are defined as participants who consent to participate in the clinical study but 
are not subsequently randomized to a cohort. A minimal set of screen failure information is 
required to ensure transparent reporting of screen failure participants to meet the 
Consolidated Standards of Reporting Trials (CONSORT) publishing requirements and to 
respond to queries from regulatory authorities. Minimal information includes demography, 
screen failure details, eligibility criteria, and any serious adverse event (SAE).
If the 90-day period between the Screening Visit (Visit 1) and Day 1 Visit (Visit 3), or 
between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20) is exceeded due to operational 
or administrative reasons (eg, enrollment pause due to regulatory or safety review, 
operational issues causing significant delays), participants will not be screen 
failed/withdrawn from the study, but will repeat some tests and assessments to re-confirm 
study/IP administration eligibility criteria, and to identify clinically significant changes in 
key tests and assessments (see Section 5.3). 
5.7. Caregiver(s)
The parent(s) or legal guardian(s) of the participant will actively participate as caregiver(s) in 
this study. As caregiver(s), the parent(s) or legal guardian(s) will not only provide informed 
consent, but will also actively participate in the study, including attendance at study visits 
and completion of clinical outcomes assessments regarding caregiver topics and on behalf of 
the participant. With consent, the caregiver’s demographic information may be collected. The 
caregiver(s) will also communicate observed safety information to the Investigator or 
designee as appropriate.
A participant’s caregiver(s) must meet all of the following criteria for the participant to be 
eligible for enrollment in the study: 

Aged ≥18 years and responsibility as a legal caregiver;

Willingness and ability to provide written informed consent on behalf of the 
participant;

Ability to accompany the participant to the clinic visits;

Ability to follow instructions.
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6. STUDY INTERVENTION
Study intervention is defined as any investigational intervention(s), marketed product(s), 
placebo, or medical device(s) intended to be administered to a study participant according to 
the study protocol.
For the purposes of this protocol, the term IP may be used synonymously with study 
intervention.
6.1. Study Intervention(s) Administered
Intervention Name
fordadistrogene movaparvovec
Placebo for fordadistrogene 
movaparvovec
Type
Gene Therapy
Placebo for Gene Therapy
Use
Experimental
Placebo
IMP and NIMP/AxMP
IMP
IMP
Dose Formulation
Sterile Solution for Infusion
Sterile Solution for Infusion
Unit Dose Strength(s)
1E14 vg/mL
Note: This is the nominal 
concentration of the IP; for lot 
specific dosing calculation, the exact 
strength of each lot will be provided.
For nominal dosing, 1E14 vg/mL will 
be the concentration used for the 
calculation of the administered dose. 
Nominal dosing will only be 
implemented for Year 2 IP 
administration. The Sponsor will 
communicate to the sites what dosing 
strategy must be implemented for 
each participant to be dosed. (Refer to 
IP Manual for further details) 
0 vg/mL
Dosage Level(s) 
2E14 vg/kg 
Single dose IV infusion
0 vg/kg
Single dose IV infusion
Route of Administration
Intravenous Infusion
Intravenous Infusion
Sourcing
Provided centrally by the Sponsor 
(Refer to IP Manual for further 
details)
Provided centrally by Sponsor (Refer 
to IP Manual for further details)
Packaging and Labeling
Study intervention will be provided as 
5 mL per vial (5 mL/vial). Each vial 
will be labeled as required per 
country requirement
Study intervention will be provided as 
5 mL per vial (5 mL/vial). Each vial 
will be labeled as required per 
country requirement
SRSD
IB
IB
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Study Intervention(s)
Intervention 
Name
IV 
methylprednisolone
Oral prednisone or 
prednisolone
Deflazacort
Eculizumab
Antiemetics 
eg. ondansetron
MenACWY 
Vaccine
Type
Drug
Drug
Drug
Drug
Drug
Vaccine 
Use
One-time, pre-
administration of IP, 
Year 1 and Year 2
Background 
glucocorticoid 
regimen pre- IP 
administration and 
after completion of 
90-day Protocol-
mandated 
glucocorticoid 
regimen for at least 
the first 2 years in 
the study.
Protocol-mandated 
post-IP dosing for 
90 days
Background 
glucocorticoid regimen 
pre- IP administration and 
after completion of 90-day 
Protocol-mandated 
glucocorticoid regimen for 
at least the first 2 years in 
the study
Medication to treat 
adverse events (aHUS), 
to be administered at the 
discretion of the 
Investigator. Guidance 
for use provided in 
Section 6.5.1
Medication to prevent or 
treat adverse events 
(nausea and/or 
vomiting), to be 
administered at 
discretion of 
Investigator. See Section 
6.5.1
Required per 
eculizumab label. 
Must be 
administered no 
later than 30 days 
before and only 
after 60 post- IP 
administration. See 
Section 6.5.1
IMP or 
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
Dose 
Formulation
Sterile solution for 
injection
Tablets or Oral 
Suspension
Tablet or Oral suspension
Sterile Solution for 
Infusion
Orally disintegrating 
tablet or sterile solution 
for injection
Solution for 
injection
Unit Dose 
Strength(s)
40 mg/mL
1 mg, 2 mg or 5 
mg
Tablets: 6 mg, 18 mg, 30 
mg or 36 mg
Oral Suspension: 22.75 
mg/mL
300 mg concentrate (10 
mg/ml)
Tablet: 4 mg or 8 mg
Injection: 2mg/mL
10 mcg group A, 
5 mcg group C, 
5 mcg group W-
135,
5 mcg group Y 
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Study Intervention(s)
Dosage Level(s)
2 mg/kg
At least 0.5 
mg/kg/day
At least 0.75 mg/kg/day
Total dose to be 
determined by the 
investigator
Total dose to be 
determined by the 
investigator
Single dose 
injection (0.5mL)
Route of 
Administration
Intravenous infusion 
Oral
Oral 
Intravenous Infusion
Oral/ injection/IV 
infusion
Intramuscular 
injection
Sourcing
Sourced by the 
clinical site using 
locally approved 
product or provided 
to the site by local 
vendors coordinated 
by the Sponsor 
Sourced by the 
clinical site using 
locally approved 
product or 
provided to the site 
by local vendors 
coordinated by the 
Sponsor 
Sourced by the clinical 
site using locally approved 
product or provided to the 
site by local vendors 
coordinated by the 
Sponsor
The sponsor will provide 
initial safety stock then 
remaining supply to be 
sourced by the clinical 
site using locally 
approved product unless 
otherwise arranged with 
the sponsor
Sourced by the clinical 
site using locally 
approved product or 
provided to the site by 
local vendors 
coordinated by the 
Sponsor 
Sourced by the 
clinical site using 
locally approved 
product or provided 
to the site by local 
vendors coordinated 
by the Sponsor 
Packaging and 
Labeling
Study intervention 
will be provided as 
locally approved 
product and labeled 
as required per 
country and site 
requirements
Study intervention 
will be provided as 
locally approved 
product and 
labeled as required 
per country and 
site requirements 
Study intervention will be 
provided as locally 
approved product and 
labeled as required per 
country and site 
requirements
Study intervention will 
be provided as 300 
mg/30mL (10mg/mL) 
vial concentrated 
solution for intravenous 
infusion.  Product will be 
labeled as required per 
country and site 
requirements.
Study intervention will 
be provided as locally 
approved product and 
labeled as required per 
country and site 
requirements
Study intervention 
will be provided as 
locally approved 
product and labeled 
as required per 
country and site 
requirements
SRSD
SmPC
SmPC
SmPC
SmPC
SmPC
SmPC
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Of the study interventions listed in the table above:  IV methylprednisolone, oral prednisone, 
or prednisolone, deflazacort, eculizumab, antiemetics e.g., ondansetron and MenACWY 
vaccine are not subject to safety reporting in accordance with Japanese regulation 
requirements. Please refer to Section 10.10 (Appendix 10).
For investigators in Japan, please refer to Section 10.10 (Appendix 10) for the reporting of 
study intervention defects.
6.1.1. Administration
PLEASE NOTE: Participants will not receive IP if they meet any of the following; 
(for Year 2 IP administration eligibility, please see Section 7.1).
1. Receipt of a treatment with gene therapy, defined as any therapy introducing 
exogenous DNA or intended to permanently alter the endogenous DNA between the 
Screening Visit (Visit 1) and the Day 1 Visit (Visit 3). Participants who receive a 
treatment with gene therapy between Screening (Visit 1) and Day 1 (Visit 3) will not 
be eligible for IP administration and will be withdrawn from the study. 
2. Receipt of a treatment designed to increase dystrophin expression (including, but not 
limited to exon-skipping and nonsense read-through) between the Screening Visit 
(Visit 1) and the Day 1 Visit (Visit 3). Participants who receive a treatment designed 
to increase dystrophin expression between Screening (Visit 1) and Day 1 (Visit 3) 
will not be eligible for IP administration and will be withdrawn from the study. 
3. Receipt of an investigational drug or investigational vaccine between the Screening 
Visit (Visit 1) and the Day 1 Visit (Visit 3). Participants who receive an 
investigational drug or investigational vaccine between Screening (Visit 1) and Day 1 
(Visit 3) will not be eligible for IP administration and will be withdrawn from the 
study.
4. Positive test for NAb to AAV9, based on the threshold determined by the Central 
Laboratory, at Baseline (Visit 2); if the analysis of NAb to AAV9 was required due to 
the first blood draw for NAb to AAV9 testing at the Day 1 (Visit 3), or most recent 
test, if repeat blood draw(s) was required, being more than 55 days after the 
Screening Visit (Visit 1), please see Section 1.3.1. Participants who have a positive 
test for NAb to AAV9 will be withdrawn from the study. 
5. Receipt of a live attenuated vaccination within 90 days prior to Day 1 (Visit 3). If a 
participant has received a live attenuated vaccination within 90 days prior to Day 1 
(Visit 3), IP administration must be delayed until at least 90 days after the last 
administration of the vaccine.
6. Receipt of an inactivated vaccine (eg, influenza, meningococcus, pneumococcus, 
Haemophilus influenzae vaccination) within 30 days prior to Day 1 (Visit 3). If a 
participant has received an inactivated vaccine within 30 days prior to Day 1 (Visit 
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3), IP administration must be delayed until at least 30 days after the last 
administration of the vaccine.
7. Receipt of an mRNA or DNA-based, or non-replicating viral vector vaccine 
(eg, against SARS-CoV2) within 30 days prior to Day 1 (Visit 3). If a participant has 
received any of the above-listed vaccines within 30 days prior to Day 1 (Visit 3), IP 
administration must be delayed until at least 30 days after the last administration of 
the vaccine.
8. Receipt of any systemic immunosuppressant agents other than glucocorticoids, 
and/or, systemic antiviral, and/or interferon therapy. If a participant has received any 
of the above-listed therapies within 30 days prior to Day 1 (Visit 3), IP administration 
must be delayed until at least 30 days after the last dose.
9. Acute infection at Day 1 (Visit 3). At Day 1 (Visit 3), participants must have been 
infection-free for at least 2 weeks. Delay of IP administration for up to 14 days is 
permitted to enable infections to become fully resolved.
10. Participants with a myocarditis diagnosed by a pediatric cardiologist between 
Screening (Visit 1) and Day 1 (Visit 3) will not be eligible for IP administration and 
will be withdrawn from the study.
Per the treatment assignment dosing schedule, participants will be admitted to the site to 
receive a single intravenous infusion of IP delivered over approximately 2 to 4 hours 
(-15 minutes or +30 minutes including flush), at a rate no more than 125 mL/hour, at Day 1 
(Visit 3) and Day 390 (Visit 20), in accordance with the Schedule of Activities, and will be 
monitored as described in Section 8.2.10. 
In lieu of their background glucocorticoid regimen, participants will receive an intravenous 
infusion of 2 mg/kg of methylprednisolone, 1 to 4 hours prior to infusion of IP, followed by 
the protocol mandated glucocorticoid regimen for 3 months, as described in Section 6.5.1.
IP shipment will be initiated once the body weight is entered into the interactive response 
technology drug management system. The appropriate amount of IP, based on the actual 
concentration for the lot and participant’s body weight (at Baseline (Visit 2) for Year 1 IP 
administration and at Day 328 (Visit 18) for Year 2 IP administration), will be prepared and 
administered in a solution of approximately 250 to 500 mL containing 1.25% human serum 
albumin. Appropriate medication and other supportive measures for management of an 
unexpected reaction to the infusion should be available in accordance with local guidelines.
For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of 
IP to be shipped to the site will be determined once the study has been restarted. Therefore, 
the weight collected at Day 328 (Visit 18) will not be entered into the interactive response 
technology drug management system during the study dosing pause. Participants will be 
evaluated for Year 2 IP eligibility when the study is restarted.
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Administration of IP should be performed by appropriately qualified, Good Clinical Practice 
(GCP)-trained, and preferably gene therapy‑experienced members of the study staff 
(eg, physician, nurse, physician’s assistant, or nurse practitioner) as allowed by local, state, 
and institutional guidance. Individuals allowed in the infusion room during IP administration 
should be limited to caregivers, the treating physician, and those involved in IP 
administration. All individuals present during administration should wear appropriate 
personal protective equipment as applicable per local practice. 
The entire contents of the IV bag containing the investigational product solution should be 
administered intravenously, and subsequently the line should be flushed with 0.45% Sodium 
Chloride Injection (same as diluent used for dose preparation) in accordance with local site 
policies and procedures to ensure complete delivery of the dose and that a closed system is 
maintained to reduce risk for all individuals present during administration.
Should participants experience any infusion reaction during the IV infusion period, the 
administration should be interrupted. If the participant has mild signs or symptoms only at 
the site of the IV line, such as pain, and/or, redness of the skin, and/or itching, it is 
recommended that the Investigator assess the infusion reaction and establish a new IV access 
if needed, as every reasonable effort should be made to complete the entirety of the dose. If 
the participant presents signs or symptoms compatible with a systemic allergic reaction, the 
infusion should be immediately stopped, and supportive care provided according to the 
Investigator’s standard of care practice. Signs or symptoms suggestive of a systemic allergic 
reaction may include: respiratory compromise such as dyspnea, wheeze-bronchospasm, 
stridor, hypoxemia; generalized cutaneous reaction (eg, generalized hives, itch-flush, swollen 
lips, tongue, uvula); reduced blood pressure or associated symptoms such as collapse, 
syncope or incontinence and/or persistent gastrointestinal symptoms such as abdominal pain 
and/or vomiting.62
The IP solution has 8-hour stability at room temperature from the start of dose preparation 
(initial IP vial puncture). The 8-hour in-use period cannot be extended, so if there is an 
interruption to the infusion, every effort should be made to resume and complete the infusion 
within this period. The investigator should establish new IV access, if needed, and complete 
the infusion provided participant safety is not compromised. The time at which the infusion 
was paused, the volume infused prior to pausing the infusion, and the time at which the 
infusion resumes should all be noted in source documentation by those involved in IP 
administration in addition to documentation required at end of infusion.
6.2. Preparation/Handling/Storage/Accountability
1. The Investigator or designee must confirm that appropriate temperature conditions 
have been maintained during transit for all study interventions received and that any 
discrepancies have been reported and resolved before use of the study intervention, as 
applicable for temperature monitored shipments. 
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2. Only participants enrolled in the study may receive study intervention and only 
authorized site staff may supply, prepare, or administer study intervention. All study 
interventions must be stored in a secure, environmentally controlled, and monitored 
(manual or automated recording) area in accordance with the labeled storage 
conditions with access limited to the Investigator and authorized site staff. At a 
minimum, daily minimum and maximum temperatures for all IP storage locations 
must be documented during which the IP is stored on site and available upon request. 
Data for nonworking days must indicate the minimum and maximum temperatures 
recorded by automated record devices, since it was previously documented for all site 
storage locations upon return to business.
3. The Investigator, institution, or the head of the medical institution (where applicable) 
is responsible for study intervention accountability, reconciliation, and record 
maintenance (ie, receipt, reconciliation, and final disposition records). All study 
interventions will be accounted for using an IP accountability form/record. 
4. Further guidance and information for the final disposition of unused study 
interventions are provided in the IP manual.
5. Any storage conditions stated in the IP manual will be superseded by the storage 
conditions stated on the product label. 
6. Study interventions should be stored in their original containers and in accordance 
with the labels. 
7. See the IP manual for storage conditions of the study intervention once diluted.
8. Any excursions from the IP label storage conditions should be reported to Pfizer upon 
discovery along with any actions taken. The site should actively pursue options for 
returning the study intervention to the storage conditions described in the labeling, as 
soon as possible. Once an excursion is identified, the study intervention must be 
quarantined and not used until Pfizer provides permission to use the study 
intervention. It will not be considered a protocol deviation if Pfizer approves the use 
of the study intervention after the temperature excursion. Use of the study 
intervention prior to Pfizer approval will be considered a protocol deviation. Specific 
details regarding the definition of an excursion and information the site should report 
for each excursion will be provided to the site in the IP manual. 
9. The Sponsor or designee will provide guidance on the destruction of used and unused 
study intervention (eg, at the site) in the IP manual. If destruction is authorized to take 
place at the Investigator site, the Investigator must ensure that the materials are 
destroyed in compliance with applicable environmental regulations, institutional 
policy, and any special instructions provided by Pfizer, and all destruction must be 
adequately documented.
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Additional details about accountability, storage, destruction, and excursion reporting can be 
found in the IP manual.
6.2.1. Preparation and Dispensing
The amount of IP shipped to the site will be based on the participant’s body weight measured 
at the Baseline Visit (Visit 2) for Year 1 IP administration and at Day 328 Visit (Visit 18) for 
Year 2 IP administration, and on the and IP concentration per vial. Approximately 14 to 
45 days, depending on the site location, is required for shipment of IP.
For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of 
IP to be shipped to the site will be determined once the study has been restarted. Therefore, 
the weight collected at Day 328 (Visit 18) will not be entered into the interactive response 
technology drug management system during the study dosing pause. Participants will be 
evaluated for Year 2 IP eligibility when the study is restarted.
The IP will be dispensed using an interactive response technology (IRT) drug management 
system for the dosing visits. A qualified staff member will dispense the IP via unique 
container numbers on the vials provided, in quantities appropriate for individual participant 
dosing once the participant is confirmed to be eligible for IP administration and admitted to 
the site for dosing.
Preparation of IP should be performed by appropriately qualified, Good Clinical Practice 
(GCP)-trained, and preferably gene therapy‑experienced pharmacist as allowed by local, 
state, and institutional guidance. It is strongly recommended to prepare the IP dosing solution 
as close to the administration time on the dosing day as possible. See the IP manual for 
instructions on how to prepare the IP for administration. The IP manual will need to be 
reviewed and acknowledged by any site staff preparing and/or administering the product. 
IP will be prepared by qualified blinded site personnel according to the IP manual. The IP 
will be administered to participants in a blinded fashion.
Only qualified personnel who are familiar with procedures that minimize undue exposure to 
themselves and to the environment should undertake the preparation, handling, and safe 
disposal of gene therapy agents. Please refer to the IP manual for detailed handling 
instructions.
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6.3. Measures to Minimize Bias: Randomization and Blinding
6.3.1. Allocation to Investigational Product
Eligible participants will be randomized into Cohort 1 or Cohort 2 (See Section 4.1) in a 
2:1 fashion, using the method of permuted blocks within each randomization strata, where 
the strata are defined by their age at Screening (<6 or ≥6 years old) with no more than 
approximately 55% of dosed participants in either of the Screening age strata. Enrollment 
will be assessed periodically, and if an imbalance is noted, enrollment of the overrepresented 
stratum may be paused until a more balanced distribution is achieved. The randomization 
schedule is generated by the Sponsor. Personnel who are directly involved in the study 
conduct are blinded to the randomization schedule.
Allocation of eligible participants to study intervention (see Section 4.1 for additional details) 
will proceed through the use of an IRT system. The site personnel (study coordinator or 
specified designee) will be required to enter or select information including, but not limited 
to, the user’s identification (ID) and password, the protocol number, and the participant 
number. The IRT system will provide a confirmation report containing the participant 
number, randomization number, and container numbers assigned. The confirmation report 
must be stored in the site’s files. 
The eligible sibling(s) will receive the same treatment with approximately the same timing 
(as long as the siblings were strictly separated from each other until both have received IP) 
and sequence based on the Cohort to which the participant is randomized (see Section 5.3) 
and study intervention for the sibling(s) will be manually assigned in the system by the IRT 
support team. Siblings will receive their own unique participant number.
IP will be dispensed at the study visits summarized in the SoA. 
The study specific IRT reference manual will provide the contact information and further 
details on the use of the IRT system. 
6.3.2. Breaking the Blind
The participants, Sponsor, vendors, and study personnel will be blinded to treatment 
allocation, except for an unblinded, medically-qualified monitor (medical monitor), 
independent from the team conducting and monitoring the study as defined in Section 7.1. 
The IRT will be programmed with blind breaking instructions. In case of an emergency, the 
Investigator has the sole responsibility for determining if unblinding of a participant’s 
treatment assignment is warranted. Participant safety must always be the first consideration 
in making such a determination. If the Investigator decides that unblinding is warranted, the 
Investigator should make every effort to contact the Sponsor prior to unblinding a 
participant’s treatment assignment unless this could delay further management of the 
participant. If a participant’s treatment assignment is unblinded, the Sponsor must be notified
by the Investigator within 24 hours after breaking the blind. The date and reason that the 
blind was broken must be recorded in the source documentation and case report form 
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(CRF)/data collection tool (DCT). Unblinding will not necessarily lead to study 
discontinuation.
The study specific IRT reference manual will provide the contact information and further 
details on the use of the IRT system to break the blind.
6.3.3. Sensitive Clinical Data
Select safety and immunogenicity results
In order to prevent the functional unblinding of the treatment assignment, the results of the 
following assessments will not be shared with the study team or the site after Year 1 IP 
administration and throughout the blinded portion of the study:

CK;

AST and ALT; 

NAb to AAV9 (See Section 7.1);

ELISpot to AAV9 and mini-dystrophin;

ADA to AAV9 and mini-dystrophin;

C3 and C4.
An unblinded medically qualified monitor (medical monitor) will review the results of CK, 
AST and ALT, NAb to AAV9, and ADA to mini-dystrophin for each participant on an 
ongoing basis and will decide if any result(s) should be repeated and/or shared with the site 
and the study team, due to a judgement that the results could reflect a safety issue (eg, liver 
injury, myositis, other immunological reaction). 
If a participant in Cohort 2 presents with a positive test for NAb to AAV9 on the sample 
taken at the Day 34 (Visit 13) he will be withdrawn from the study given that it would 
already be determined at that time that he is not be eligible for fordadistrogene 
movaparvovec administration at Year 2. If this situation occurs while the study is still 
accruing participants, an additional 2 participants may be randomized for each Cohort 2 
participant who is withdrawn.
Additionally, if the threshold of laboratory abnormalities for a potential drug-induced liver 
injury (DILI) case has been met (see Appendix 6), the results for ALT and AST will be 
shared with the site and the study team until the potential DILI has been investigated and it is 
considered resolved. 
If a clinical event occurs that, in the opinion of the Sponsor and/or the Investigator, could be 
due to an immunological reaction, additional ad-hoc assessments of NAb to AAV9, ADA to 
AAV9 and mini-dystrophin, ELISpot to AAV9 and mini-dystrophin may be conducted if 
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considered indicated by the Sponsor and/or the Investigator for the interpretation and/or the 
management of the immunological reaction. The results of these tests will be shared with the 
site and the study team.
Additionally, to further prevent the introduction of bias in the scoring of the functional 
assessments, all possible measures should be put into place to prevent the clinical evaluators 
from viewing the participants´ medical records/database where relevant information that 
could lead to functional unblinding, such as the occurrence of lab abnormalities or 
AEs/SAEs, may be recorded.
Viral vector shedding results
In order to prevent the functional unblinding of the treatment assignment, the results of the 
following assessments will not be shared with the site or the study team throughout the 
blinded portion of the study:

Viral vector shedding.
An unblinded qualified Sponsor representative, independent and firewalled from the study 
team, will review the viral vector shedding results for each participant on an ongoing basis. 
The unblinded qualified Sponsor representative will communicate to the site when sampling 
in a given matrix (ie, blood, urine, or saliva) for each participant can be stopped. For 
Cohort 1 participants sampling for each matrix will be stopped when two consecutive 
samples test negative. To prevent unblinding, sampling will also be stopped for a matched 
Cohort 2 participant.
Muscle biopsy results
In order to prevent the functional unblinding of the treatment assignment, the results of the 
following assessments will not be shared with the site or the study team throughout the 
blinded portion of the study:

Percent normal mini-dystrophin expression level, quantified by LC-MS. 

Percent of muscle fibers expressing mini-dystrophin, assessed by 
immunohistochemistry.
No review of these results will be conducted by the unblinded medical monitor. 
Year 2 IP eligibility laboratory results
Given that the below eligibility assessment does not apply to Cohort 1 for Year 2 IP 
administration and in order to prevent unblinding of the treatment assignment, when 
assessing Cohort 2 participants’ eligibility for Year 2 IP administration, the following test 
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results will not be shared with the sites and the study team, and will only be reviewed by an 
unblinded medical monitor (see Section 7.1).

Laboratory results at Day 360 (Visit 19):
NAb to AAV9;
Absolute neutrophil count <1000 cells/mm3;
Platelets <150 x 103/µl;
Cystatin C >1.2 x ULN;
Positive hepatitis A virus (anti-HAV) immunoglobulin M, hepatitis B surface antigen 
(HbsAg), and/or hepatitis C antibody (HCVAb);
Markers of hepatic inflammation or overt or occult cirrhosis as evidenced by one or 
more of the following:

PT > ULN; prolonged INR >ULN;

GLDH >2 x ULN;

Total bilirubin >1.5 x ULN (unless the participant has a history of Gilbert 
disease) and direct bilirubin >0.5 mg/dL;

GGT >1.5 x ULN.
6.4. Study Intervention Compliance
The IP will be administered by the appropriately designated study staff at the Investigator 
site.
6.5. Concomitant Therapy
6.5.1. Permitted Therapies
Background glucocorticoid regimen (daily dose of ≥0.5 mg/kg/day prednisone or 
prednisolone, or ≥0.75 mg/kg/day deflazacort). There should be no changes to the 
background glucocorticoid regimen in the first two years of the study, except as described for
the protocol-mandated glucocorticoid regimen, below. A change to the glucocorticoid 
regimen is defined as:

A change >0.2 mg/kg in daily dose;

A change in the specific glucocorticoid (prednisone, prednisolone, or deflazacort);

A change in regimen (ie, from daily to any non-daily).
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This definition also applies during the 3 months before the Screening Visit (Visit 1).
After two years (Day 749), any change to the background glucocorticoid regimen will be 
permitted. 
Protocol-mandated glucocorticoid regimen for Year 1 and Year 2: to mitigate the risk of 
an immune response, participants will temporarily replace their background glucocorticoid 
regimen as follows:
1. Between 1 and 4 hours prior to IP administration: single dose of IV 
methylprednisolone 2 mg/kg. Note: Participants must be instructed to not take their 
background glucocorticoid dose on Day 1 (Visit 3) and on Day 390 (Visit 20).
2. From 1 to 15 days post-IP administration: 2 mg/kg/day oral prednisone or 
prednisolone.
3. From 16 to 30 days post-IP administration: 1.5 mg/kg/day oral prednisone or 
prednisolone.
4. From 31 to 60 days post-IP administration: 1.0 mg/kg/day oral prednisone or 
prednisolone.
5. From 61 to 90 days post-IP administration: 0.75 mg/kg/day oral prednisone or 
prednisolone.
A temporary increase in the daily dose of glucocorticoids, protocol mandated or background 
regimen, will be allowed only if medically required, after consultation with the Sponsor. 
Following IP administration, participants with vomiting who cannot tolerate oral medications 
can receive IV glucocorticoids instead of oral glucocorticoids, per the clinical judgement of 
the Investigator. The dose of IV glucocorticoids must be consistent with the requirements of 
the protocol. The participants must return to oral glucocorticoids as soon as the Investigator 
considers that it is safe to do so.
Participants may return to their background glucocorticoid regimen after 90 days post-IP 
administration as long as there is no immune response or other clinical indication.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined 
Year 2 IP  administration will not receive their protocol-mandated glucocorticoid regimen in 
Year 2 and will continue receiving their background glucocorticoid treatment during Year 2, 
see Appendix 12 and Section 7.2.1.
Participants with delayed Year 2 IP administration will not receive their protocol-mandated 
glucocorticoid regimen until the pause is lifted and Year 2 IP administration takes place; they 
will remain on their background glucocorticoid regimen until then, see Section 5.3.2.
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Eculizumab
Treatment with one or more doses of the complement inhibitor, eculizumab, should be 
considered by the Investigator, according to the local prescribing information, for any 
participant who presents with a clinical picture of complement-mediated thrombotic 
microangiopathy. Signs consistent with atypical hemolytic uremic syndrome (aHUS) that 
would indicate the need for treatment include: 
1. Creatinine >2 x Screening value; OR
2. Platelets <75 x 103/µl AND either (a) or (b):
a.
Evidence of hemolysis:

Haptoglobin <LLN or reduced to <50% from Screening value (Year 1) or 
from Visit 19 value (Year 2); or 

Schistocytes on blood smear.
b. Evidence of nephropathy: 

Anuria >12 hours; or 

≥2+ blood or protein on urine dipstick; or 

An increase of >50% in serum creatinine from Screening value. 
Because the use of eculizumab increases the risk of contracting serious meningococcal 
infections, participants who have no contraindications and who have not previously received 
a vaccination against meningococcus or whose last vaccination at the time of the Screening 
Visit (Visit 1) is outside the time period of active coverage specified by the vaccine 
manufacturer must receive at least one dose of meningococcal conjugate (MenACWY) 
vaccine as early as possible in the Screening Period and not later than 30 days before IP 
administration. If they receive eculizumab, and depending on the duration of the treatment 
with eculizumab, a decision will be made as to whether they should receive a second dose of 
meningococcal vaccination or antibiotic prophylaxis, at the discretion of the Investigator. 
Participants must also receive serogroup B meningococcal (MenB) vaccination if indicated 
by national vaccination guidelines. The Investigator must evaluate the immunization status 
against meningococcus and any other locally required immunization for all participants at 
Screening (Visit 1); local eculizumab prescribing information, including additional 
vaccination, and other requirements must also be followed as needed. Additionally, all sites 
must have the MenACWY vaccine, MenB vaccine (if recommended in the national 
vaccination guidelines) and eculizumab available for all participants (eculizumab should be 
available for the first 2 months after IP administration at Year 1 and at Year 2). For 
participants who cannot receive meningococcal vaccination, antibiotic coverage must be 
provided simultaneously with eculizumab.
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Participants who experience an event compatible with aHUS may be screened for a genetic 
predisposition to aHUS, as determined by the Investigator in consultation with the Sponsor to 
increase the understanding of the risk of developing aHUS (see Appendix 2). 
Antiemetics
At the discretion of the Investigator, participants may be administered an oral antiemetic such 
as oral ondansetron following IP administration and following the local prescribing 
information to prevent or treat symptoms of nausea and vomiting. Participants (and/or 
caregivers) should be instructed to contact the site if vomiting continues despite anti-emetic 
treatment. If required, an IV antiemetic such as ondansetron may be administered by the site.
Anesthesia
Participants will also receive anesthesia according to the site standard of care for the muscle 
biopsies obtained in this study.
Vaccines
Participants will be able to receive any required live attenuated vaccine(s) only during the 
following periods:
1. Up to 90 days before Day 1 (Visit 3).
2. Day 60 (Visit 14) to Day 300. In addition, participants in Cohort 1 confirmed to meet 
exclusion criterion 15 will be allowed to receive any required live attenuated 
vaccine(s) for the remainder of the study. For details on the retrospective assessment 
of exclusion criterion 15, please see Appendix 12.
3. Day 450 until the end of the study.
Participants will be able to receive an inactivated vaccine (eg, influenza, meningococcal, 
pneumococcal, Haemophilus influenzae) only during the following periods:
1. Up to 30 days before Day 1 (Visit 3)
2. Day 60 to Day 360 (Visit 19). In addition, participants in Cohort 1 confirmed to meet 
exclusion criterion 15 will be allowed to receive any required inactivated vaccine(s) 
for the remainder of the study. For details on the retrospective assessment of 
exclusion criterion 15, please see Appendix 12.
3. Day 450 until the end of the study.
Participants will be able to receive an mRNA, or DNA-based, or non-replicating viral vector 
vaccine (eg, against SARS-CoV2) only during the following periods: 
1. Up to 30 days before Day 1 (Visit 3)
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2. Day 60 to Day 360 (Visit 19). In addition, participants in Cohort 1 confirmed to meet 
exclusion criterion 15 will be allowed to receive any required mRNA, or DNA-based, 
or non-replicating viral vector vaccine(s) (eg, against SARS-CoV2) for the remainder 
of the study. For details on the retrospective assessment of exclusion criterion 15, 
please see Appendix 12.
3. Day 450 until the end of the study.
Other medications
With the exception of any prohibited therapies, other medications may be used if deemed 
necessary by the Investigator.
6.5.2. Prohibited Therapies
The following therapies are prohibited from the time of signing the informed consent until 
the end of Year 2. After Day 749 (Visit 35) participants will be able to receive any of the 
therapies listed below, if deemed necessary. For Cohort 1 participants confirmed to meet 
exclusion criterion 15 and for participants who declined Year 2 IP administration (see 
Section 7.2.1), the medications listed below will be prohibited only until the end of Year 1. 
After Day 360 (Visit 19) these participants will be able to receive any of the therapies listed 
below, if deemed necessary. For details on the retrospective assessment of exclusion criterion 
15, please see Appendix 12.
1. Immunosuppressant agents (other than glucocorticoids, see Section 6.5.1) unless 
administered in response to immunologic reaction.
2. Investigational therapies, including those being evaluated for the treatment of DMD 
(eg, idebenone, tamoxifen).
3. Antiviral therapy, unless administered to treat an acute viral infection 
(eg, COVID-19).
4. Interferon therapy, unless administered to treat an acute viral infection and the 
participant is at least 2 months post IP administration.
Any therapy designed to increase dystrophin expression (including, but not limited to 
exon skipping and nonsense read-through) will be prohibited during the first 52 weeks of the 
study. When participants have completed Day 360 (Visit 19), if the Investigator determines 
that, due to worsening of DMD, an approved therapy with this mechanism were deemed 
necessary, such therapy would then be allowed. 
Gene therapy, defined as any therapy introducing exogenous DNA or intended to 
permanently alter the endogenous DNA, will be prohibited from the signing of the informed 
consent until the end of the study.
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6.5.3. Rescue Medicine 
Not applicable.
6.6. Dose Modification 
Not applicable. 
6.7. Intervention After the End of the Study
No intervention will be provided to study participants at the end of the study.
7. DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL
7.1. Discontinuation of Study Intervention
In the context of this study, treatment will consist of two single intravenous infusions, one of 
fordadistrogene movaparvovec and one of placebo (Section 4.1). Following IP administration 
on Day 1 (Visit 3), the only potential for discontinuation of study intervention is at the time 
of IP administration in Year 2. Cohort 1 participants will receive placebo on Day 390 
(Visit 20) and will not be discontinued from study intervention although the timing of IP 
administration may be affected by eligibility criteria, as described below, in order to preserve 
the blinding of the ongoing study. Cohort 2 participants are scheduled to receive 
fordadistrogene movaparvovec one year after receiving placebo if they remain eligible for 
Year 2 IP administration. Participants in Cohort 2 who are determined to be ineligible to 
receive fordadistrogene movaparvovec by the criteria listed below (1-6) will discontinue 
study intervention. 
Cohort 2 participants will be confirmed to be eligible for Year 2 IP administration before 
receiving treatment with fordadistrogene movaparvovec. There are no eligibility criteria for 
Cohort 1 participants for Year 2 IP administration based on the results of hematology and 
chemistry profiles or of results of testing for NAb to AAV9, but they will be reviewed for 
safety reasons. In order to preserve the blinding of the ongoing study, an unblinded, 
medically qualified monitor (medical monitor), independent from the team conducting and 
monitoring the study, will be the only person to review the results of the hematology and 
chemistry profiles as well as of the NAb to AAV9. These laboratory results will be blinded to 
the site and the Sponsor. 
Additionally, the unblinded medical monitor will determine if any test(s) should be repeated 
(due to a result outside of allowable limits for Year 2 IP administration eligibility considered 
possibly transient for Cohort 2 participants, and/or due to test showing a potential safety 
issue considered possibly transient for Cohort 1 and Cohort 2 participants). The unblinded 
medical monitor will also decide if any result(s) must be unblinded to the site and the 
Sponsor, in the unlikely event that it reflects a safety issue.
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Cohort 2 participants will not be eligible for Year 2 IP administration if they present with any 
of the following:
1. Positive test for NAb to AAV9, based on the threshold determined by the Central 
Laboratory, at Day 360 (Visit 19). If the time between Day 360 (Visit 19) and 
Day 390 (Visit 20) is more than 55 days, a second NAb to AAV9 test must be 
performed and confirmed to be negative before Year 2 IP administration. Dosing 
cannot occur unless there is a negative NAb to AAV9 test from a sample collected 55 
or less days before the day of IP administration, as reviewed by the unblinded 
medical monitor.
2. Abnormality in hematology or chemistry profiles at Day 360 (Visit 19). A single 
repeat for value(s) outside allowable limits is permitted to re-assess eligibility: 
Absolute neutrophil count <1000 cells/mm3;
Platelets <150 x 103/µl;
Cystatin C >1.2 x ULN;
Positive hepatitis A virus (anti-HAV) immunoglobulin M, hepatitis B surface antigen 
(HbsAg), and/or hepatitis C antibody (HCVAb);
Markers of hepatic inflammation or overt or occult cirrhosis as evidenced by one or 
more of the following:

PT > ULN; prolonged INR >ULN;

GLDH >2 x ULN;

Total bilirubin >1.5 x ULN (unless the participant has a history of Gilbert 
disease) and direct bilirubin >0.5 mg/dL;

GGT >1.5 x ULN.
Additionally, the unblinded medical monitor will confirm the treatment allocation for 
participants with the conditions listed below, so those participants in Cohort 2 who meet any 
of these conditions do not receive Year 2 IP administration and are withdrawn from the 
study:
3. Participants screened or randomized who had not yet received Year 2 IP 
administration and were retrospectively confirmed to meet exclusion criterion 15 (see 
Appendix 12).
4. LVEF <50% on echocardiogram performed at Day 360 (Visit 19), or at the unplanned 
visit to re-assess eligibility for Year 2 IP administration.
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5. Diagnosis of current or prior myocarditis by a pediatric cardiologist.
6. Not a candidate for mechanical cardiac or respiratory support, or any other invasive 
intervention, if indicated for management of an acute event as determined by the 
cardiologist in consultation with the investigator.
Cohort 1 participants, as confirmed by the unblinded medical monitor, will not receive 
Year 2 IP administration, placebo, if they meet exclusion criterion 15. They will not require 
post-IP safety monitoring in Year 2, will not attend Visit 18 in Year 1 and Visits 20 to 30.2 in 
Year 2, and will not receive their protocol-mandated glucocorticoid regimen in Year 2. These 
participants will remain in the study for safety monitoring as described in Appendix 12.
Once the unblinded medical monitor has communicated to the Investigator that the 
participant meets eligibility criteria based on laboratory tests and echocardiographic results, 
then the Investigator will ensure that none of the criteria listed below are met before allowing 
IP administration. 
To preserve the blinding of the treatment assignment for the site and for the Sponsor, the 
following criteria will be assessed for both Cohort 1 and Cohort 2 participants.
7. Receipt of a live attenuated vaccination within 90 days prior to Day 390 (Visit 20). If 
a participant has received a live attenuated vaccination within 90 days prior to 
Day 390 (Visit 20), IP administration must be delayed until at least 90 days after the 
last administration of the vaccine. 
8. Receipt of an inactivated vaccine (eg, influenza, meningococcal, pneumococcal, 
Haemophilus influenzae vaccination) within 30 days prior to Day 390 (Visit 20). If a 
participant has received an inactivated vaccine within 30 days prior to Day 390 (Visit 
20), IP administration must be delayed until at least 30 days after the last 
administration of the vaccine.
9. Receipt of an mRNA or DNA-based, or non-replicating viral vector vaccine 
(eg, against SARS-CoV2) within 30 days of Day 390 (Visit 20). If a participant has 
received any of the above-listed vaccines within 30 days prior to Day 390 (Visit 20), 
IP administration must be delayed until at least 30 days after the last administration of 
the vaccine.
10. Receipt of any systemic immunosuppressant agents other than glucocorticoids, and/or 
systemic antiviral therapy, and/or interferon. If a participant has received any of these 
therapies, IP administration must be delayed until at least 30 days after the last dose.
11. Acute infection at Day 360 (Visit 19) that, in the judgement of the Investigator, is not 
expected to be fully resolved at least 14 days prior to IP administration on Day 390 
(Visit 20).
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12. Additionally, any participant, in Cohort 1 or Cohort 2, who has received gene therapy 
(other than IP) after Year 1 IP administration will not be eligible for Year 2 IP 
administration but will not be withdrawn from the study. 
If any of the above eligibility criteria (7-11) are met for Cohort 1 or Cohort 2 participants, IP 
administration will be delayed until none of the criteria are met. If the time between the 
blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned 
Day 390 Visit (Visit 20) exceeds 13 weeks (90 days), due to operational or administrative 
reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing 
significant delays), then the clinical safety laboratory tests should be repeated and eligibility 
(re)confirmed prior to administering IP. The participant will not be withdrawn due to 
exceeding the time between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20).
If a Cohort 2 participant is determined to be permanently ineligible for Year 2 IP 
administration, because of a confirmed result for the hematology or chemistry profiles 
outside allowable limits or because of a positive test for NAb to AAV9, based on the 
threshold determined by the Central Laboratory, he will be withdrawn from the study. The 
medical monitor will inform the site of the decision, to allow the site to communicate with 
the participant and the caregiver. In this circumstance, no Early Discontinuation Visit will be 
required. 
7.1.1. Temporary Discontinuation 
Not applicable.
7.1.2. Rechallenge
Not applicable.
7.2. Participant Discontinuation/Withdrawal From the Study 
A participant may withdraw from the study at any time at his own request.
Reasons for discontinuation from the study include the following:

Refused further follow-up;

Lost to follow-up;

Death;

Study terminated by Sponsor;

Participant is determined to be not eligible for Year 1 (Cohort 1 and Cohort 2 
participants) or Year 2 IP administration (only for Cohort 2 participants).
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
Participants randomized before the approval of protocol amendment 6, but not dosed, 
will be withdrawn from the study if they meet exclusion criterion 15, based on the 
retrospective review of the results of the genetic testing by the investigator.
If a request is made to withdraw from the study, an alternative to withdrawal should be 
offered that would enable the collection of key data, including adverse events. Alternative 
methods may include phone contact with the participant and/or caregiver. Documentation 
should be made that all alternatives have been offered to the participant and/or caregiver. 
At the time of discontinuing from the study, if possible, an early discontinuation visit should 
be conducted. See the SoA for assessments to be collected at the time of study 
discontinuation and follow-up and for any further evaluations that need to be completed. 
The Early Discontinuation Visit applies only to participants who are enrolled/randomized 
and then are prematurely withdrawn from the study, except participants withdrawn because 
they do not fulfil eligibility criteria for Year 1 (Section 6.1.1) or Year 2 administration (only 
Cohort 2 participants) (Section 7.1). Participants should be queried regarding their reason for 
withdrawal. The participant will be permanently discontinued both from the study 
intervention and from the study at that time. Lack of completion of all or any of the 
withdrawal/early termination procedures will not be viewed as protocol deviations so long as 
the participant’s safety was preserved.
If a participant withdraws from the study, he may request destruction of any remaining 
samples, taken and not tested, and the Investigator must document any such requests in the 
site study records and notify the Sponsor accordingly.
If the participant withdraws from the study and also withdraws consent (see Section 7.2.1) 
for disclosure of future information, no further evaluations should be performed and no 
additional data should be collected. The Sponsor may retain and continue to use any data 
collected before such withdrawal of consent.
Lack of completion of all or any of the withdrawal/early termination procedures will not be 
viewed as protocol deviations so long as the participant’s safety was preserved.
7.2.1. Withdrawal of Consent 
Participants/caregivers who decline Year 1 IP administration will be withdrawn from the 
study; those who decline Year 2 IP administration will remain in the study and will continue 
to be followed as indicated in Section 1.3.1, footnote “f” and in Section 1.3.2, footnotes “bb” 
and “cc”, see also Section 6.5.1, 6.5.2 and 8.2.10. The only exception to this is when a 
participant/caregiver specifically withdraws consent for any further contact with them or 
persons previously authorized by the participant to provide this information. Participants or 
caregiver(s), should notify the Investigator in writing of the decision to withdraw consent 
from future follow-up, whenever possible. The withdrawal of consent should be explained in 
detail in the medical records by the Investigator and entered on the appropriate CRF page. In 
the event that vital status (whether the participant is alive or dead) is being measured, 
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publicly available information should be used to determine vital status only as appropriately 
directed in accordance with local law.
7.3. Lost to Follow-Up 
A participant will be considered lost to follow up if he repeatedly fails to return for scheduled 
visits and is unable to be contacted by the site.
The following actions must be taken if a participant fails to return to the clinic for a required 
study visit:

The site must attempt to contact the participant and reschedule the missed visit as 
soon as possible and counsel the participant on the importance of maintaining the 
assigned visit schedule and ascertain whether or not the participant wishes to and/or 
should continue in the study;

Before a participant is deemed lost to follow-up, the Investigator or designee must 
make every effort to regain contact with the participant (where possible, 3 telephone 
calls and, if necessary, a certified letter to the participant’s last known mailing 
address or local equivalent methods). These contact attempts should be documented 
in the participant’s medical record;

Should the participant continue to be unreachable, he will be considered to have 
withdrawn from the study. 

Discontinuation of specific sites or of the study as a whole is handled as part of 
Appendix 1.
8. STUDY ASSESSMENTS AND PROCEDURES
The Investigator (or an appropriate delegate at the Investigator site) must obtain a signed and 
dated ICD and assent, as appropriate, before performing any study specific procedures. 
Study procedures and their timing are summarized in the SoA. Protocol waivers or 
exemptions are not allowed.
Immediate safety concerns should be discussed with the Sponsor immediately upon 
occurrence or awareness to determine if the participant should continue or discontinue study 
intervention.
Adherence to the study design requirements, including those specified in the SoA, is essential 
and required for study conduct.
All screening evaluations must be completed and reviewed to confirm that potential 
participants meet all eligibility criteria. The Investigator will maintain a screening log to 
record details of all participants screened and to confirm eligibility or record reasons for 
screening failure, as applicable.
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Every effort should be made to ensure that protocol required tests and procedures are 
completed as described. However, it is anticipated that from time to time there may be 
circumstances outside the control of the Investigator that may make it unfeasible to perform 
the test. In these cases, the Investigator must take all steps necessary to ensure the safety and 
well-being of the participant. When a protocol required test cannot be performed, the 
Investigator will document the reason for the missed test and any corrective and preventive 
actions that he or she has taken to ensure that required processes are adhered to as soon as 
possible. The study team must be informed of these incidents in a timely manner.
For samples being collected and shipped, detailed collection, processing, storage, and 
shipment instructions and contact information will be provided to the Investigator site prior 
to initiation of the study.
The total blood sampling volume for individual participants in this study is approximately 
400 mL. The actual collection times of blood sampling may change. Additional blood 
samples may be taken for safety assessments at times specified by Pfizer, provided the total 
volume taken does not exceed 5% of the participant’s estimated total blood volume during 
any period of 4 consecutive weeks.
Due to the potential for insufficient blood to be collected in participants with difficult venous 
access, and to ensure priority samples are collected, the suggested order of sample collection 
is described below.
NAb to AAV9 (at Screening Visit [Visit 1] and Baseline Visit [Visit 2] only; otherwise 
drawn after ELISpot). On Day 360 Visit (Visit 20), blood samples for NAb to AAV9 
should be collected first, unless collection of clinical safety samples is required for the 
management of a safety issue.
Clinical safety 
ELISpot
ADA
Banked biospecimens for biomarkers
If a participant has a peripherally inserted central catheter (PICC) line, it must only be used 
for blood collections and not for IP administration.
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8.1. Efficacy Assessments
8.1.1. North Star Ambulatory Assessment (NSAA)
The NSAA is a 17-item test that grades performance of various functional skills using the 
following scale: 0 (unable to achieve independently), 1 (modified method but achieves goal 
independent of physical assistance from another), and 2 (“normal”- no obvious modification 
of activity) [Mazzone et al., 2009].60 The NSAA total score is calculated as the sum of the 
individual item responses and ranges from 0 to 34 with higher scores indicating better 
function. For two of the 17 items (rise from floor and run/walk 10 meters) the time to 
complete the skill (in seconds) is also recorded. If the participant is not able to perform the 
NSAA due to acute illness or injury, and not due to disease progression, the NSAA should be 
recorded as not done. If, in the opinion of the Investigator, the acute illness or injury has 
resolved and the participant is still not able to perform the NSAA or has lost ambulation 
(Section 8.1.6), then this should be reflected in scoring of the NSAA.
In order to assure the ongoing quality of the clinical evaluators’ ability to perform functional 
assessments (NSAA, ankle range of motion and FVC) video recording may be used at 
pre-specified visits, as indicated in the SoA. If CE re-training is required, the assigned master 
physiotherapist may request additional visits to be recorded and reviewed. Videos will be 
reviewed by the master physiotherapist to provide feedback to the clinical evaluators on the 
method used to perform the functional assessment. Videos will not be used to provide 
scoring of the participant’s functional assessment. The videos will be stored at the site and 
retained per the record retention requirements until the end of the study.
Whenever possible the same CE should administer the NSAA for the same participant 
throughout the study. 
Additional details regarding the administration and scoring of the NSAA are provided in the 
Functional Assessment Manual.
8.1.2. Ankle Range of Motion (ROM)
Ankle (talocrural) passive dorsiflexion will be evaluated using goniometry. The development 
of ankle contractures is common in the age range of the participants, contributes to 
difficulties with ambulation, and causes pain. The degrees of motion will be recorded. 
Additional details are provided in the Functional Assessment Manual.
8.1.3. Muscle Biopsies
In order to evaluate the expression and distribution of mini-dystrophin, muscle biopsies will 
be collected in approximately the first 15 participants randomized into Cohorts 1 and 2 (and 
their siblings) from sites that have been trained and certified by the Sponsor/Sponsor 
designee to collect open muscle biopsies, with the potential to collect a maximum of 33 if 
needed. In addition, these samples may be used for the evaluation of exploratory biomarkers 
that may include markers related to dystrophin, DMD or similar diseases, or the mechanism 
of action of fordadistrogene movaparvovec. 
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Open muscle biopsies will be taken from the biceps brachii at two time points, one at 
Baseline and two post-Baseline. The post-Baseline muscle biopsies will be performed on 
Day 360 (Visit 19) and on Day 1830 (Visit 41). 
The biopsies will be performed by a healthcare professional with adequate experience, as 
evaluated by the Sponsor beforehand. This procedure will be performed using anesthesia (eg, 
regional block or under general anesthesia) according to institutional standards, by a 
qualified anesthesiologist with adequate experience in treating pediatric patients with DMD, 
as evaluated by the Sponsor beforehand. Muscle biopsies should only be performed after any 
imaging and functional assessments scheduled for the same visit have been completed.
Specific instructions regarding post-operative care will also be provided to the participants 
and their caregiver(s) after the procedure. 
Muscle biopsies will be analyzed centrally and in a blinded fashion. Detailed collection, 
processing, storage, and shipment instructions will be provided in the biopsy and central 
laboratory manuals. Additional training on the aforementioned procedures will be provided 
by the Sponsor or Sponsor representative.
If, following initial processing for the percent normal mini-dystrophin expression using the 
LC-MS assay and for the percent of muscle fibers expressing mini-dystrophin using the 
immunofluorescence assay, there is remaining muscle tissue from the biopsy, it may be 
stored for further analysis. This would enable repeat processing and analysis for these two 
secondary endpoints, if needed. 
In addition, unless prohibited by local regulations or IRB/EC decision, participants will be 
asked to indicate on the consent document whether they will allow their biopsy samples to be 
banked so that they might also be used to design and conduct research in order to gain a 
further understanding of other diseases and to advance science, including development of 
other medicines for patients. This component of the sampling banking is optional for 
participants; they may still participate in the study even if they do not agree to the additional 
research on their banked samples. The optional additional research does not require the 
collection of any further samples.
In the event of an SAE affecting skeletal and/or cardiac muscle, an ad-hoc muscle biopsy will 
be performed, if possible, to aid the diagnosis and/or management of the event. If a site has 
not been previously trained and certified to collect muscle biopsies by the Sponsor or 
designee, training will be completed before the biopsy is performed. Ad-hoc muscle biopsies 
will also be analyzed centrally and in a blinded fashion, unless determined otherwise by the 
investigator or the Sponsor.
Investigators should discuss the possibility of an ad-hoc muscle biopsy with participants and 
caregivers during the review of the ICD.
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8.1.4. Forced Vital Capacity (FVC)
For participants ≥6 years old at the Screening Visit (Visit 1), spirometry will be performed 
using standardized equipment in accordance with the American Thoracic Society/European 
Respiratory Study Task Force: standardization of lung function testing guidelines 2005 
[Miller et al., 2012].63 Sufficient forced expiratory maneuvers (up to a maximum of 6) will be 
performed to produce at least 3 technically adequate tracings. The best (largest) FVC 
measurement from the set of 3 will be used to determine the FVC and the %pFVC according 
to age, height, race and gender [Qanjer et al., 2012].64
Whenever possible the same CE or trained respiratory therapist (if approved by the sponsor) 
should perform the spirometry for the same participant throughout the study.
Additional details regarding the assessment of FVC are provided in the Functional 
Assessment Manual.
8.1.5. Actigraphy
Activity monitors will be placed on the ambulatory participant’s ankle prior to performing 
the NSAA at study visits and are to be worn continuously for the next 2 weeks to capture 
real-life activities. 
8.1.6. Ambulatory Status/Loss of Ambulation
After the Screening Visit (Visit 1) ambulatory status will be assessed as follows:

At each visit in which an assessment of ambulatory status occurs, per the SoA, the 
following assessments will occur: caregivers will be asked to report whether the 
participant is able to walk to perform activities of daily living and, if not, when the 
last date was on which he was able to do so;

At each visit when ambulatory status is assessed, the NSAA will be attempted.
Loss of ambulation will be defined as:

A caregiver report that the participant is not currently able to walk to perform 
activities of daily living (as determined by the Lowes Lab Ambulatory Status 
Algorithm (LASA) described in the QoL & ADL Manual), AND

Inability to perform the walk item of the NSAA (unless considered temporary due to 
acute illness or injury) on the visit following the date on which the caregiver stated 
the participant lost the ability to ambulate.
The date for loss of ambulation will be recorded as the date reported by the caregiver as the 
last date on which the participant was able to walk to perform activities of daily living.
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If loss of ambulation occurs, the NSAA will no longer be assessed and the scores will be 
recorded in the CRF at each visit per SoA, to reflect that the participant was unable to 
achieve any skill unassisted. Additionally, the ankle activity monitoring will be removed. 
8.1.7. Clinical Outcome Assessments
Clinical outcomes assessments (COAs) will be completed by the caregiver and clinical 
evaluator throughout the study. Ideally, the same caregiver will complete caregiver reported 
COAs during the study. The same clinical evaluator will administer the NSAA and complete 
the clinical evaluator reported NSAA anchor question at each visit. Depending on the 
participant’s age, and at the discretion of the Investigator and caregiver, COAs may also be 
completed by the participants themselves. Details regarding administration of these 
assessments, training, and any additional requirements will be provided in the Health-Related 
Quality of Life and Activities of Daily Living Assessment Manual.
8.1.7.1. Caregiver-Completed Assessments
8.1.7.1.1. Modified Pediatric Outcomes Data Collection Instrument (PODCI) –
Pediatric Parent
In order to evaluate participants’ musculoskeletal health status, PODCI questionnaire scales 
will be collected. The Modified PODCI – Pediatric Parent includes the Transfer and Basic 
Mobility Core Scale (11 items) and the Sports and Physical Functioning Core Scale 
(21 items) from the original PODCI measure for a total of 32 items that assess a participant’s 
ability to walk, stand, and perform activities of daily living. The pediatric parent version will 
be completed by caregivers of participants. The scales each produce an independent, 
standardized score ranging from 0-100, with lower scores representing lower levels of 
function. 
8.1.7.1.2. EuroQol 5 Dimensions – Youth Health Questionnaire Proxy Version 
(EQ-5D-Y Proxy)
The EQ-5D-Y Proxy is a recently developed generic instrument that measures the health 
status of children. The measure is completed by a caregiver and captures how he or she rates 
the health of the child. It was adapted from the original EQ-5D questionnaire developed by 
the EuroQol Group. The EQ-5D-Y Proxy includes five dimensions: mobility (walking 
around), selfcare (taking care of him/herself), usual activities (doing usual activities), 
pain/discomfort (having pain or discomfort), and anxiety/depression (feeling worried, sad, or 
unhappy). Responses record three levels of severity: no problems, some problems, a lot of 
problems. The EQ-5D-Y Proxy also includes a standard vertical 20 cm visual analogue scale 
(VAS) for recording current health related quality of life on a scale from 0 to 100, with 
0 representing the worst and 100 the best health state he or she can imagine. All items refer 
to the health state “today”. 
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8.1.7.1.3. Patient Global Impression of Severity – Ambulatory Activities of Daily Living 
(Caregiver-report; PGIS:CG)
The Patient Global Impression of Severity – Ambulatory Activities of Daily Living 
(Caregiver -report; PGIS:CG) is a caregiver-completed, 2-item measure of their child’s 
current ability to perform daily activities that require the use of their legs (ie, ambulatory 
motor function). Motor function is assessed using a 5-point Likert scale with the following 
options: able to do all, able to do many, able to do some, able to do very little, not able to do 
any. The PGIS:CG is collected to enable an anchor based method for interpreting changes in 
the NSAA total score and Modified PODCI scale scores. Details of these analyses will be 
described in a separate analysis plan.
8.1.7.1.4. EQ-5D-5L
The EQ-5D-5L will be completed by caregivers regarding their own quality of life. The 
EQ-5D-5L descriptive system is comprised of 5 dimensions: mobility, self-care, usual 
activities, pain/discomfort, and anxiety/depression. Each dimension has 5 response levels: no 
problems, slight problems, moderate problems, severe problems, unable to/extreme 
problems. The EQ-5D-5L index score is a single number summary of the responses to the 5 
dimensions and reflects how good or bad a health state is according to the preferences of the 
general population of a country/region. The index score is derived by applying a formula that 
attaches values (weights) to each of the levels in each dimension. The EuroQol Group 
develops and maintains a collection of index values (weights) for all possible EQ-5D health 
states for specific countries/regions.
The EQ-5D-5L also includes a standard vertical 20 cm VAS for recording current 
health-related quality of life on a scale from 0 to 100, with 0 representing the worst and 100 
the best health state imaginable. All items refer to the caregiver’s health state “today”.
8.1.7.2. Participant Completed Assessments
8.1.7.2.1. Modified PODCI – Adolescent 
The Modified PODCI – Adolescent contains a total of 29 items that assess a participant’s 
ability to walk, stand, and perform activities of daily living. Two subscales from the original 
PODCI are included: the Transfer and Basic Mobility Core Scale (11 items) and the Sports 
and Physical Functioning Core Scale (18 items). Participants will become eligible to 
complete the measure at 11 years of age. See Section 8.1.7.1.1. 
8.1.7.2.2. EuroQol 5 Dimensions – Youth Health Questionnaire (EQ-5D-Y)
Participants will become eligible to complete the self-report version of the EQ-5D-Y at 
8 years of age. See Section 8.1.7.1.2.
8.1.7.2.3. Patient Global Impression of Severity – Ambulatory Activities of Daily Living 
(Self-report; PGIS)
The Patient Global Impression of Severity – Ambulatory Activities of Daily Living (PGIS) is 
a self-reported, 2-item measure of a participant’s current ability to perform daily activities 
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that require the use of their legs (ie, ambulatory motor function) adapted from the PGIS:CG 
(See Section 8.1.7.1.3). Participants will become eligible to complete the PGIS at 11 years of 
age. The PGIS is collected to enable an anchor-based method for interpreting changes in the 
NSAA total score and Modified PODCI scale scores. Details of these analyses will be 
described in a separate analysis plan.
8.1.7.3. Clinical Evaluator-Completed Assessment 
8.1.7.3.1. Clinician Global Impression of Severity – Ambulatory Motor Function 
(CGIS)
The Clinician Global Impression of Severity – Ambulatory Motor Function (CGIS) is a 
clinical evaluator-reported, 1-item measure of a participant’s overall ambulatory motor 
function. Motor function is assessed using a 5-point Likert scale with the following options: 
no ambulatory motor function, a little ambulatory motor function, some ambulatory motor 
function, much ambulatory motor function, complete ambulatory motor function. The recall 
period is “today”. The CGIS will be completed by the same clinical evaluator who completes 
the NSAA at each visit. The CGIS is collected to enable an anchor-based method for 
interpreting changes in the NSAA total score and Modified PODCI scale scores. Details of 
these analyses will be described in a separate analysis plan.
8.1.8. Rater Qualifications 
For specific rating assessments, only qualified raters will be allowed to evaluate and/or rate 
participants in this study. The minimum qualifications a rater must meet for each study rating 
assessment will be outlined in the Functional Assessment Manual provided to each 
participating site. The level of experience with the target population (or equivalent), specific 
scale experience (or equivalent), and certification required (if applicable) will be listed and 
used to determine whether a rater is approved for a given assessment. Proposed raters who do 
not meet specific criteria but who may be qualified based on unique circumstances may be 
individually reviewed by the study clinical team to determine whether or not a waiver may be 
issued. The rater must become certified to perform selected study assessments before he or 
she can participate in the conduct of the study. For specifically defined assessments, rater 
training and standardization exercises may be conducted, and written and signed 
documentation will be provided by the site for each rater’s certification. In return, each site 
will be provided written and signed documentation outlining each rater’s certification for 
specific study assessments. Recertification may be required at periodic intervals during the 
study. The raters who administer specific study assessments will be documented in a 
centralized location and all site staff who administer ratings will be verified in the site study 
documentation during the conduct of the study. Following certification, a Rater ID will be 
provided to each CE. The CE is responsible for recording their Rater ID on each completed 
worksheet.
8.2. Safety Assessments
Planned time points for all safety assessments are provided in the SoA. Unscheduled clinical 
laboratory measurements may be obtained at any time during the study to assess any 
perceived safety concerns.
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8.2.1. Physical Examinations
A complete physical examination will be conducted by a qualified healthcare professional 
and will include, at a minimum, assessments of the head, ears, eyes, nose, mouth, skin, heart 
and lung, lymph nodes, gastrointestinal, and musculoskeletal systems. 
A brief physical examination will be conducted by a qualified healthcare professional and 
will include, at a minimum, assessments of general appearance, chest (heart and lungs), 
abdomen, musculoskeletal (joints, tenderness, presence of new fractures, joint contractures).
Investigators should pay special attention to clinical signs related to previous serious 
illnesses. 
8.2.2. Neurological Examinations
The complete neurological examination will be conducted by a neurologist and will include 
an assessment of mental status, cranial nerves II-XII, the motor system (upper and lower limb 
bulk strength, right and left separately), deep tendon reflexes, the sensory system, station, 
gait, and coordination. 
The brief neurological examination will also be conducted by a neurologist and will include 
an assessment of the motor system (upper and lower limb bulk strength, right and left 
separately) as well as station and gait.
8.2.3. Height and Weight Measurements
Weight will be measured with a calibrated digital scale placed on a stable, flat surface. Sites 
may use a sponsor-provided calibrated scale or their own institutional calibrated scale. Body 
weight measurement must be verified by two site personnel. Participants must remove shoes, 
bulky layers of clothing, and jackets so that only light clothing remains. They must also 
remove the contents of their pockets and remain still during measurement of weight. 
Preferably both height and weight measurements will be collected in the morning. 
Participants should be instructed to step gently onto the scale, place both feet together in the 
center of the scale and stand straight with eyes directed ahead. Participants should be 
instructed to stand still and not sway. Measurement will be recorded after the weight has 
stabilized. Body weight should be reported with precision to one decimal place (eg, 0.1 kg). 
A 10-kg certified weight will be purchased by the Sponsor and sent to each site. To assess the 
accuracy of the scale, the trial coordinator or appointed designee will weigh him or herself 
alone, then the weight alone, and finally, the individual together with the weight. Deviations 
of more than one scale division (±0.1 kg) will require corrective action and the Sponsor must 
be contacted. Accuracy checks will be performed before each visit when weight is to be 
measured. For participants who are no longer able to stand, weight will be measured, if 
possible, using a wheelchair scale.
Height will be measured with the participant standing without shoes on a flat surface and 
with the heels touching the ground. For participants who are not able to stand, or who have 
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contractures that prevent standing with the heels on the ground, height will not be measured 
but will be estimated by ulna length. Refer to the Functional Assessment Manual for details.
8.2.4. Vital Signs
Body temperature, pulse rate, respiratory rate, and supine blood pressure will be assessed 
before blood collection for laboratory tests.
Supine blood pressure and pulse rate measurements will be assessed once with a completely 
automated device. Manual techniques will be used only if an automated device is not 
available.
Blood pressure and pulse rate measurements should be preceded by at least 5 minutes of rest 
for the participant in a quiet setting without distractions (eg, television, cell phones).
O2 saturation will only be measured before the start of the IP infusion and during the 
inpatient stay post IP administration (see Sections 1.3.1 and Section 1.3.2).
8.2.5. Electrocardiograms
A single 12-Lead ECG will be collected using an ECG machine, provided by the Sponsor, 
that automatically calculates the heart rate and measures PR, QT, corrected QT (QTc) 
intervals and QRS complex. The Fridericia corrected QTc (QTcF) will be the basis for safety 
monitoring of QT intervals. All scheduled ECGs should be performed after the participant 
has rested quietly for at least 10 minutes in the supine position. ECG data will be submitted 
to a central laboratory for measurement and interpretation and will also be reviewed at the 
site for safety monitoring. 
If a post-dose QTcF interval remains ≥30 msec from the baseline and is >450 msec; or b) an 
uncorrected QT or QTcF value is ≥500 msec for any scheduled ECG for greater than 4 hours 
(or sooner, at the discretion of the Investigator), or if QTcF intervals get progressively 
longer, the participant should undergo continuous ECG monitoring. A cardiologist should be 
consulted if QTc intervals do not return to less than the criteria listed above after 8 hours of 
monitoring (or sooner, at the discretion of the Investigator). 
The final ECG report from the central laboratory should be maintained in the participant’s 
source documentation as well as the final interpretation of the ECG recording. Any clinically 
significant changes from the Screening ECG may potentially be AEs (Appendix 7) and 
should be evaluated further, as clinically warranted. 
If the leads are placed incorrectly on the participant´s limbs, the ECG should be repeated. It 
is important that leads be placed in the same and correct positions each time in order to 
achieve precise ECG recordings. If a machine-read QTc value is prolonged, the Fridericia 
QT correction should be obtained to interpret whether a safety event has occurred as defined 
above.
ECG values of potential clinical concern are listed in Appendix 7. 
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8.2.6. Echocardiogram
Echocardiograms will be collected and read locally for immediate interpretation and safety 
monitoring and will be submitted to a central laboratory for standardized interpretation.
To ensure safety of the participants, a qualified individual at the site will evaluate the 
echocardiogram at least for left ventricular ejection fraction (LVEF), but other parameters 
may also be assessed, including but not limited to myocardial strain. Echocardiogram should 
be performed using a 2-D imaging collection method. 
If the LVEF is below 50% on the echocardiogram at any visit after screening, the participant 
should be referred to a cardiologist for further assessment.
8.2.7. Cardiac Troponin I
To monitor for cardiac injury, cTn-I will be assessed. If a local laboratory cannot perform the 
cTn-I assay, cTn-T can be substituted for the local laboratory assessments.
If a participant presents with a Screening cTn-I value >3 x 99th percentile the following 
instructions should be followed:

Perform clinical evaluation for cardiac signs or symptoms;

Review Screening ECG for significant findings suggestive of ischemia;

If either of the above is positive, repeat cTn-I approximately 48 to 96 hours after the 
first blood draw and request a cardiology consult.
The algorithm in Figure 3 provides instructions for the management of elevated cTn-I (or 
cTn-T) values during the course of the study, after the Screening visit.
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Figure 3.
Management of Elevated Cardiac Troponin I (cTn-I)/Cardiac Troponin T 
(cTn-T) values
*Results of cTn-I should only be compared to results of cTn-I and results of cTn-T should only be compared to 
results of cTn-T.
†Echocardiogram and NT-ProBNP/BNP are required only during the first 14 days post IP administration.
‡ECG, echocardiogram, and cardiac MRI (original and follow-up scans) performed during the evaluation of an 
elevated cardiac troponin value must be read locally for immediate interpretation and safety monitoring and will 
be submitted to a central reader as soon as possible (i.e., in less than 72 hours) for standardized interpretation. 
For events of elevated troponin or myocarditis with or without abnormal findings in the initial cardiac MRI, a 
follow up cardiac MRI will be performed approximately 3 months after the start of the event. This cardiac MRI 
will be reviewed at the site for safety monitoring and will also be submitted to the imaging CRO for 
measurement and interpretation as soon as possible (i.e., in less than 72 hours).
# Sites will repeat troponin and NT-ProBNP tests (or BNP, if NT-ProBNP is not available) approximately every 
48-72 hours until each test returns to Baseline values or reaches a level considered not clinically significant by 
the investigator.
NOTE: If at any time during the study a participant presents with a cTn-I value >3 x 99th
percentile and he had not been previously evaluated, the instructions for evaluation outlined 
in the algorithm should be followed.
8.2.8. Cardiac MRI
Cardiac MRI will be performed using a 1.5T or 3.0T scanner with an appropriate coil for 
cardiac imaging. The scan may include imaging before and after IV administration of a 
gadolinium-based contrast agent. Sites will be responsible for confirming participant 
eligibility to undergo MRI scanning and gadolinium contrast administration. If the site 
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considers gadolinium contrast administration unsafe, or if the participant has a history of 
allergy to gadolinium, cardiac MRI without contrast administration will be performed.
Complete details on the cardiac MRI acquisition protocol, image quality review, and 
transmission of data to the imaging contract research organization (CRO) will be provided in 
an Imaging Manual offered to the study sites. The imaging CRO will include central review 
of all cardiac MRI scans. The central reviewer analysis will include, at a minimum, 
evaluation of LVEF, myocardial fibrosis as measured by late gadolinium enhancement 
(LGE) if gadolinium is used, and evaluation of myocardial strain. Cardiac MRIs (original and 
any follow-up scans) performed due to an acute event, as per Section 8.2.7, will be submitted 
to the imaging CRO for measurement and interpretation as soon as possible (i.e., in less than 
72 hours), and will also be reviewed at the site for safety monitoring. For events of elevated 
troponin or myocarditis with or without abnormal findings in the initial cardiac MRI, a 
follow up cardiac MRI will be performed approximately 3 months after the start of the event. 
This cardiac MRI will be reviewed at the site for safety monitoring and will also be 
submitted to the imaging CRO for measurement and interpretation as soon as possible (i.e., 
in less than 72 hours).
8.2.8.1. Management of Incidental Findings
An incidental finding is one unknown to the participant that has potential health or 
reproductive importance, which is discovered unexpectedly in the course of a research study, 
but is unrelated to the purpose and beyond the aims of the study.
Cardiac MRI images will be reviewed by the central review facility. The purpose of this 
review is to evaluate images for LVEF, LGE, and strain over time. Central image review is 
not a complete medical review of the participant. If, during the central review process, an 
unexpected observation is identified and this finding could, in the opinion of the central 
reviewer, have a significant health or reproductive consequence, this finding may be shared 
with the study sponsor for disclosure to the investigator. All follow-up testing and final 
diagnosis will be left to the discretion of the medical professionals at the site or those with an 
existing physician participant relationship. The investigator will be responsible for reporting 
any AEs identified from incidental findings as described in the AE reporting section. 
Identification of such incidental findings during the central review process should not be 
expected, and the site maintains responsibility for performing a general safety review of all 
images in accordance with site protocols.
8.2.9. Clinical Safety Laboratory Assessments
See Appendix 2 for the list of clinical safety laboratory tests to be performed and the SoA for 
the timing and frequency.
The Investigator or their designee must review the laboratory report, document this review, 
and record any clinically relevant changes occurring during the study in the AE section of the 
CRF. Clinically significant abnormal laboratory findings are those which are not associated 
with the underlying disease, unless judged by the Investigator to be more severe than 
expected for the participant’s condition.
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All laboratory tests with values considered clinically significantly abnormal during 
participation in the study should be repeated until the values return to normal or baseline or 
are no longer considered clinically significant by the Investigator or medical monitor.
If such values do not return to normal/baseline within a period of time judged reasonable by 
the Investigator, the etiology should be identified and the Sponsor notified.
All protocol-required laboratory assessments, as defined in Appendix 2, must be conducted 
in accordance with the laboratory manual and the SoA.
8.2.10. Post IP Intensified Safety Monitoring (at Year 1 and Year 2)
Due to the potential for an immune reaction against the AAV9 vector and/or the transgene, 
participants will undergo an intensified safety monitoring period for the first 34 days after IP 
administration in Year 1 and in Year 2.
Following IP administration, participants will be monitored as inpatients for 7 days, or 
longer, if deemed necessary by the Investigator (see SoA for details). Participants must be in 
an individual room, ie, not shared with other patients. Following IP administration, it is 
recommended that the IV line remains for at least 48 hours in case IV hydration or treatment 
is necessary due to nausea, vomiting, anorexia, etc.  Once the IV line is removed, volume 
status should be assessed regularly, and if a participant subsequently experiences nausea or 
vomiting, consideration should be given to the placement of an IV line for treatment with an 
IV anti-emetic, hydration and replacement of the oral protocol-mandated glucocorticoid 
regimen by an IV regimen (see Section 6.5.1). Upon discharge, participants will be asked to 
stay local to the site (ie, if they do not live near the site, they will be asked to stay in at an 
overnight facility) through Day 14 after Year 1 and Year 2 IP administration, or longer, if 
deemed necessary by the Investigator. If adverse events possibly related to IP administration 
are observed, participants should not be discharged until the events have resolved. 
Once enrollment is complete and the last participant has completed 14 days post Year 1 IP 
administration, the E-DMC will review the safety information accrued to determine if any 
changes to the Year 2 IP administration schedule, including need for and length of 
hospitalization, are required.
During the first 34 days post IP administration participants will undergo study visits on: 

Year 1: Day 2 (Visit 4), Day 4 (Visit 5), Days 6-10 (Visits 6-10), Day 14 (Visit 11), 
Day 21 (Visit 12, a remote visit is allowed) and Day 34 (Visit 13), for clinical and 
laboratory assessments. 

Year 2: Day 2 (Visit 21), Day 4 (Visit 22), Days 6-10 (Visits 23-27), Day 14 (Visit 
28), Day 21 (Visit 29, a remote visit is allowed) and Day 34 (Visit 30), for clinical 
and laboratory assessments. Cohort 1 participants confirmed to meet exclusion 
criterion 15 and participants who declined Year 2 IP administration will not attend 
these visits (see Section 1.3.2 footnote “bb”, and Appendix 12).
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Local Laboratory Assessments

On Visit 2 and Visits 4 to 10 (Day 2 to 10) at Year 1, and Visits 20 to 27 (Days 1 to 
10) at Year 2, the sites will perform blood and urine safety tests at their local 
laboratories. This will ensure a very rapid turnaround (within 1 to 2 hours) and review 
of the results during a period that is critical for the detection of immune mediated-
adverse events.

When copies of medical records including local laboratory reports are provided to 
Pfizer for the purpose of critical safety review, all participant identifiers, with the 
exception of the participant number, must be redacted on the copies of the medical 
records before submission to Pfizer. The files should be password-protected.
Participants and their caregivers will be instructed to carefully monitor the liquid intake and 
urinary output of the participants for the first 34 days post IP administration (see 
Section 5.5.2 for additional details). Participants will be required to return to the site for 
evaluation by the Investigator or designated medically qualified individual, within 24 hours if 
any of the following occur:

No urine output for 12 hours, or a significant change in urine output in less than 
24 hours, or observation of tea-colored urine; 

Evidence of significant reduction in estimated glomerular filtration rate, determined 
by clinically relevant increases in serum cystatin C or serum creatinine (eg, doubling) 
from value at the Screening Visit (central laboratory) or from value at the Baseline 
Visit (local laboratory) at Year 1 or from Visit 19 at Year 2;

Clinically relevant increase from Screening value in hematocrit or hemoglobin;

Presence of anion gap acidosis; 

Abnormality on blood smear, or haptoglobin <LLN or reduced to <50% from 
Screening value (indicating unequivocal hemolysis); 

Platelets <75 x 103/µl.
Hospital admission and/or treatment with eculizumab, as per Section 6.5.1, or additional 
immunosuppression may be warranted, at the discretion of the Investigator and/or Sponsor.
Since admission to the intensive care or coronary unit is a possibility which could involve 
placement of a central catheter and/or an endomyocardial biopsy to aid diagnosis and 
management, and/or mechanical circulatory and/or respiratory support, investigators should 
discuss the possibility of these interventions with the pediatric cardiologist (sub-investigator). 
These measures should be discussed with participants and caregivers during the review of the 
ICD.
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Investigators in Japan should see Section 10.10 (Appendix 10) for details on the management 
of the participants during the first 14 days post IP administration.
8.2.11. Additional Safety Monitoring
Caregivers should be instructed to monitor participants, particularly within the first 90 days 
following each IP administration, to determine if they have a significant change in their 
ability to perform typical activities of daily living including chewing, swallowing, speaking, 
and walking, or if they have cardiac symptoms such as chest pain or pressure, palpitations, 
shortness of breath, edema in the lower extremities, or dizziness. If any of these occur, 
participants (and/or caregivers) should be instructed to promptly contact the site for a 
possible unscheduled visit and/or biospecimen collection. Investigators will closely monitor 
the participant during this time for muscle weakness or any other signs or symptoms of 
skeletal or cardiac muscle inflammation or injury. All DMD participants permitted in the 
study, including those with mutations between exons 30-41 or at exon 55, may be at potential 
risk of heart muscle injury and/or skeletal muscle damage or inflammation and will be 
carefully monitored as indicated above.
8.2.12. Local and Central Laboratory Testing
Some of the laboratory testing at Year 1 and at Year 2 will be made by the local laboratory at 
each site to ensure fast turnaround of test results. In order to preserve the blinding of the 
study by no sharing the results of sensitive clinical data (Section 6.3.3), on some of these 
visits the sites will also send a separate sample to the central laboratory for C3 and C4 
analysis. For the same reason, AST and ALT will not be analyzed locally and instead, to 
monitor hepatic safety, at Year 1, on Day 9 (Visit 9) and at Year 2 on Day 9 (Visit 26), the 
sites will send a separate sample to the central laboratory for GLDH analysis. Cardiac 
troponin will also be analyzed by the central laboratory at Day 7 (Visit 7) in Year 1 and Day 
7 (Visit 24) in Year 2. Cardiac troponin I (or cardiac troponin T when cardiac troponin I is 
not available) will be assessed locally at the following visits: Baseline Visit (Visit 2), Day 2 
(Visit 4), Day 4 (Visit 5), Day 6, Day 8, and Day 10 (Visit 6, Visit 8, and Visit 10) in Year 1; 
Day 390 (Visit 20) pre-IP administration, Day 391 (Visit 21), Day 393 (Visit 22), Day 395 
(Visit 23), Day 397 (Visit 25) and Day 399 (Visit 27) in Year 2. Local serum creatinine will 
also be collected at the following visits: Baseline Visit (Visit 2), Day 2 (Visit 4) and Day 4 
(Visit 5) in Year 1, and Day 390 (Visit 20) pre-IP administration, Day 391 (Visit 21) and Day 
393 (Visit 22) in Year 2. See Appendix 2 for additional details. For sites in Japan only: local 
and central laboratory testing will also be collected at Visits 4 and 5 in Year 1, and Visits 21 
and 22 in Year 2; see Appendix 2 for details. For sites in Russia, local and central laboratory 
testing will also be collected from Day 14 (Visit 11) to Day 240 (Visit 17) in Year 1, and 
from Day 403 (Visit 28) to Day 629 (Visit 34) in Year 2; see Appendix 2 and Appendix 15
for details.
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Table 2.
Routine Local Laboratory Testing in Year 1 and Year 2
Year 1 Visits
Visit 1
Visit 2
Visit 3
Visit 4
Visit 5
Visit 6
Visit 7
Visits 
8&9
Visit 
10
Year 2 Visits
N/A
N/A
Visit 
20
Visit 
21
Visit 
22
Visit 
23
Visit 
24
Visits 
25&26
Visit 
27
Hematology
Xa
Xa
X
X
X
X
Chemistry and 
hepatic safety
Xa
Xa
X
X
X
X
Cystatin Cc
Xa
Xa
Xc
Xc
Xc
Xc
Urinalysis
Xa
Xa
X
X
X
X
Cardiac 
troponin I (or 
T)
X
Xb
X
X
X
Xd
X
Serum 
creatinine
X
Xb
X
X
Haptoglobin
Xa
Xa
a.
Only for sites in Japan.
b.
To be collected pre-IP administration, and only at Year 2, Visit 20.
c.
To be analyzed when possible at the site.
d.
Only at Visit 8 in Year 1, and at Visit 25 in Year 2.
Note that this table only shows the local laboratory tests to be collected at these visits. For complete 
information, including what laboratory tests are sent to the central laboratory see Appendix 2.
8.2.13. Mood and Behavior Risk Monitoring 
The Child Behavior Check List (CBCL) was designed to assess behavior problems and social 
competency in children. There are two versions: the 100-item pre-school questionnaire for 
ages 1.5 to 5 years, and the 120-item school-age questionnaire for ages 6 to 18 years. The 
caregiver will complete the age-appropriate version of the CBCL at Screening (Visit 1) and 
subsequent visits, as indicated on the SoA, based on the participant’s behavior. For this 
study, scores on the Withdrawn (pre-school) or Withdrawn/Depressed (school-age) syndrome 
scale and on the Internalizing global scale (both versions) will be examined for high-risk 
behaviors. Higher scores on the CBCL indicate higher levels of problematic behaviors or 
dysfunction. The CBCL scoring algorithm allows for a participant’s scores to be standardized 
using scores from a normal population. These standardized scores are referred to as T-scores. 
A threshold of ≥65 on the T-scores for the Withdrawn and Withdrawn/Depressed syndrome 
scales and a threshold of ≥60 on the Internalizing global scale indicate clinically significant 
behaviors. 
An assessment of the participant’s psychological status will be completed by the Investigator 
if a participant has a CBCL T-score of ≥65 in the Withdrawn or Withdrawn/Depressed 
syndrome scales and/or a T-score of ≥60 in the Internalizing global scale. The Investigator is 
required to determine whether it is safe for the participant to enroll and/or continue study 
participation and/or if additional assessment is indicated. If additional assessment is 
indicated, and/or if scores remain elevated on subsequent assessment, and/or if an event of 
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self-harm occurs, an evaluation will be performed by one of the following child and 
adolescent mental health providers (MHP): 

In the United States: 1) Child and Adolescent Psychiatrists (board certified or board 
eligible), or psychiatrists who have training and experience in the diagnosis and 
treatment of psychiatric disorders in the pediatric population, or 2) Psy. D. or Ph.D. 
level Clinical Psychologists, licensed Master’s level Clinical Social Workers or 
licensed Psychiatric Nurse Practitioners who have training and experience in the 
diagnosis and treatment of psychiatric disorders in the pediatric population. 

In countries outside the United States: individuals with similar training and 
experience as those described above.
Written documentation of the risk assessment by the Investigator and/or the MHP should be 
included in the participant’s source documentation and the risk assessment CRF will be 
completed. The risk assessment CRF serves as further verification that the psychiatric 
evaluation and assessment of participant safety have been completed. 
If the MHP determines that additional psychiatric assessment is warranted, the participant 
should be referred to a psychiatrist or psychologist for further assessment.
Additional details regarding these assessments, including training and any additional 
requirements, will be provided.
8.2.14. Pregnancy Testing
Not applicable.
8.3. Adverse Events and Serious Adverse Events
The definitions of an AE and an SAE can be found in Appendix 3.
AEs will be reported by the participant (or, when appropriate, by a caregiver, surrogate, or 
the participant’s legally authorized representative).
The Investigator and any qualified designees are responsible for detecting, documenting, and 
recording events that meet the definition of an AE or SAE and remain responsible to pursue 
and obtain adequate information both to determine the outcome and to assess whether it 
meets the criteria for classification as an SAE or that caused the participant to discontinue the 
study (see Section 7). 
In addition, the Investigator may be requested by Pfizer Safety to obtain specific follow-up 
information in an expedited fashion.
8.3.1. Time Period and Frequency for Collecting AE and SAE Information
The time period for actively eliciting and collecting AEs and SAEs (“active collection 
period”) for each participant begins from the time the participant provides informed consent, 
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which is obtained before the participant’s participation in the study (ie, before undergoing 
any study-related procedure and/or receiving investigational product), through and including 
a minimum of 1 year after the last IP administration. 
In the Long-term Follow-up period (ie, Years 3 through 6), active elicitation and collection of 
AEs and SAEs occurs on a bi-yearly basis. 
For participants who are screen failures, the active collection period ends when screen failure 
status is determined.
Follow-up by the Investigator continues throughout and after the active collection period and 
until the event or its sequelae resolve or stabilize at a level acceptable to the Investigator, and 
Pfizer concurs with that assessment.
If the participant withdraws from the study and also withdraws consent for the collection of 
future information, the active collection period ends when consent is withdrawn.
If a participant definitively discontinues or temporarily discontinues the study because of an 
AE or SAE, the AE or SAE must be recorded on the CRF and the SAE reported using the CT 
SAE Report Form.
Investigators are not obligated to actively seek AEs or SAEs after conclusion of the study 
participation. However, if the Investigator learns of any SAE, including a death, at any time 
after a participant has been discharged from the study, and he/she considers the event to be 
reasonably related to the study intervention or study participation, the Investigator must 
promptly notify the Sponsor.
8.3.1.1. Reporting SAEs to Pfizer Safety
All SAEs occurring in a participant during the active collection period are reported to Pfizer 
Safety on the CT SAE Report Form immediately and under no circumstance should this 
exceed 24 hours, as indicated in Appendix 3. The Investigator will submit any updated SAE 
data to the Sponsor within 24 hours of it being available.
SAEs occurring in a participant after the active collection period has ended are reported to 
Pfizer Safety if the Investigator becomes aware of them; at a minimum, all SAEs that the 
Investigator believes have at least a reasonable possibility of being related to investigational 
product must be reported to Pfizer Safety.
8.3.1.2. Recording Nonserious AEs and SAEs on the CRF
All nonserious AEs and SAEs occurring in a participant during the active collection period, 
which begins after obtaining informed consent as described in Section 8.3.1, will be recorded 
on the AE section of the CRF.
During the active collection period, both nonserious AEs and SAEs are recorded on the CRF.
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8.3.2. Method of Detecting AEs and SAEs
The method of recording, evaluating, and assessing causality of AEs and SAEs and the 
procedures for completing and transmitting SAE reports are provided in Appendix 3.
Care will be taken not to introduce bias when detecting AEs and/or SAEs. Open-ended and 
nonleading verbal questioning of the participant is the preferred method to inquire about 
AE occurrences.
8.3.3. Follow-up of AEs and SAEs
After the initial AE/SAE report, the Investigator is required to proactively follow each 
participant at subsequent visits/contacts. For each event, the Investigator must pursue and 
obtain adequate information until resolution, stabilization, the event is otherwise explained, 
or the participant is lost to follow-up (as defined in Section 7.3).
In general, follow-up information will include a description of the event in sufficient detail to 
allow for a complete medical assessment of the case and independent determination of 
possible causality. Any information relevant to the event, such as concomitant medications 
and illnesses, must be provided. In the case of a participant death, a summary of available 
autopsy findings must be submitted as soon as possible to Pfizer Safety. 
Further information on follow-up procedures is given in Appendix 3.
8.3.4. Regulatory Reporting Requirements for SAEs
Prompt notification by the Investigator to the Sponsor of an SAE is essential so that legal 
obligations and ethical responsibilities towards the safety of participants and the safety of a 
study intervention under clinical investigation are met.
The Sponsor has a legal responsibility to notify both the local regulatory authority and other 
regulatory agencies about the safety of a study intervention under clinical investigation. The 
Sponsor will comply with country-specific regulatory requirements relating to safety 
reporting to the regulatory authority, institutional review boards (IRBs)/ethics committees 
(ECs), and Investigators.
Investigator safety reports must be prepared for suspected unexpected serious adverse 
reactions (SUSARs) according to local regulatory requirements and Sponsor policy and 
forwarded to Investigators as necessary.
An Investigator who receives an Investigator safety report describing an SAE or other 
specific safety information (eg, summary or listing of SAEs) from the Sponsor will review 
and then file it along with the Investigator’s brochure and will notify the IRB/EC, if 
appropriate according to local requirements. Investigators in Japan should see Section 10.10
(Appendix 10).
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8.3.5. Environmental Exposure, Exposure During Pregnancy or Breastfeeding, and 
Occupational Exposure
Environmental exposure occurs when a person not enrolled in the study as a participant 
receives unplanned direct contact with or exposure to the study intervention. Such exposure 
may or may not lead to the occurrence of an AE or SAE. Persons at risk for environmental 
exposure include healthcare providers, family members, and others who may be exposed. An 
environmental exposure may include EDP, EDB, and occupational exposure.
Any such exposures to the study intervention under study are reportable to Pfizer Safety 
within 24 hours of Investigator awareness.
8.3.5.1. Exposure During Pregnancy
An EDP occurs if: 

A male participant who received study intervention inseminates a female partner.

A female nonparticipant is found to be pregnant while being exposed or having been 
exposed to study intervention due to environmental exposure. Below are examples of 
environmental EDP:
o
A female family member or healthcare provider reports that she is pregnant after 
having been exposed to the study intervention by skin, mucosal contact, or ingestion.
o
A male family member or healthcare provider who has been exposed to the study 
intervention by skin, mucosal contact, or ingestion then inseminates his female 
partner .
o
A female nonparticipant reports that she is pregnant and has been exposed through 
viral shedding by a study participant within 2 months after dosing, and a month prior 
to or during pregnancy.
o
A male nonparticipant who has been exposed through viral shedding by a study 
participant within 2 months after dosing of study drug inseminates a pregnant female 
a month prior to or during the pregnancy.
The investigator must report EDP to Pfizer Safety within 24 hours of the investigator’s 
awareness, irrespective of whether an SAE has occurred. The initial information submitted 
should include the anticipated date of delivery (see below for information related to 
termination of pregnancy). 

If EDP occurs in a participant’s partner, the investigator must report this information to 
Pfizer Safety on the CT SAE Report Form and an EDP Supplemental Form, regardless of 
whether an SAE has occurred. Details of the pregnancy will be collected after the start of 
study intervention and until study end.
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
If EDP occurs in the setting of environmental exposure, the investigator must report 
information to Pfizer Safety using the CT SAE Report Form and EDP Supplemental 
Form. Since the exposure information does not pertain to the participant enrolled in the 
study, the information is not recorded on a CRF; however, a copy of the completed CT 
SAE Report Form is maintained in the investigator site file.
Follow up is conducted to obtain general information on the pregnancy and its outcome for 
all EDP reports with an unknown outcome. The investigator will follow the pregnancy until 
completion (or until pregnancy termination) and notify Pfizer Safety of the outcome as a 
follow up to the initial EDP Supplemental Form. In the case of a live birth, the structural 
integrity of the neonate can be assessed at the time of birth. In the event of a termination, the 
reason(s) for termination should be specified and, if clinically possible, the structural 
integrity of the terminated fetus should be assessed by gross visual inspection (unless 
preprocedure test findings are conclusive for a congenital anomaly and the findings are 
reported).
Abnormal pregnancy outcomes are considered SAEs. If the outcome of the pregnancy meets 
the criteria for an SAE (ie, ectopic pregnancy, spontaneous abortion, intrauterine fetal 
demise, neonatal death, or congenital anomaly [in a live born baby, a terminated fetus, an 
intrauterine fetal demise, or a neonatal death]), the investigator should follow the procedures 
for reporting SAEs. Additional information about pregnancy outcomes that are reported to 
Pfizer Safety as SAEs follows: 

Spontaneous abortion including miscarriage and missed abortion should be reported as an 
SAE;

Neonatal deaths that occur within 1 month of birth should be reported, without regard to 
causality, as SAEs. In addition, infant deaths after 1 month should be reported as SAEs 
when the investigator assesses the infant death as related or possibly related to exposure 
to the study intervention. 
Additional information regarding the EDP may be requested by the sponsor. Further follow 
up of birth outcomes will be handled on a case-by-case basis (eg, follow-up on preterm 
infants to identify developmental delays). In the case of paternal exposure, the investigator 
will provide the participant with the Pregnant Partner Release of Information Form to deliver 
to his partner. The investigator must document in the source documents that the participant 
was given the Pregnant Partner Release of Information Form to provide to his partner.
8.3.5.2. Exposure During Breastfeeding
An EDB if:

A female nonparticipant is found to be breastfeeding while being exposed or having been 
exposed to study intervention (ie, environmental exposure). An example of 
environmental exposure during breastfeeding is a female family member or healthcare 
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provider who reports that she is breastfeeding after having been exposed to the study 
intervention by skin, mucosal contact, or ingestion.

A female nonparticipant is found to be breastfeeding while having been exposed through 
viral shedding by a study participant within 2 months after dosing of study drug, and a 
month prior to or during breast feeding.
The investigator must report exposure during breastfeeding to Pfizer Safety within 24 hours 
of the investigator’s awareness, irrespective of whether an SAE has occurred. The 
information must be reported using the CT SAE Report Form. When exposure during 
breastfeeding occurs in the setting of environmental exposure, the exposure information does 
not pertain to the participant enrolled in the study, so the information is not recorded on a 
CRF. However, a copy of the completed CT SAE Report Form is maintained in the 
investigator site file.
An EDB report is not created when a Pfizer drug specifically approved for use in 
breastfeeding women (eg, vitamins) is administered in accord with authorized use. However, 
if the infant experiences an SAE associated with such a drug, the SAE is reported together 
with the EDB.
8.3.5.3. Occupational Exposure
The investigator must report any instance of occupational exposure to Pfizer Safety within 24 
hours of the investigator’s awareness using the CT SAE Report Form, regardless of whether 
there is an associated SAE. Since the information does not pertain to a participant enrolled in 
the study, the information is not recorded on a CRF; however, a copy of the completed CT 
SAE Report Form is maintained in the investigator site file.
8.3.6. Cardiovascular and Death Events
Collected as part of routine safety monitoring.
8.3.7. Disease-Related Events and/or Disease-Related Outcomes Not Qualifying as AEs 
or SAEs
Not applicable.
8.3.8. Adverse Events of Special Interest
Not applicable.
8.3.8.1. Lack of Efficacy
Not applicable.
8.3.9. Medical Device Deficiencies
Not applicable.
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8.3.10. Medication Errors
Medication errors may result from the administration or consumption of the investigational 
product by the wrong participant, or at the wrong time, or at the wrong dosage strength. 
Exposures to the investigational product under study may occur in clinical trial settings, such 
as medication errors.
Safety Event
Recorded on the CRF
Reported on the CT SAE Report 
Form to Pfizer Safety Within 
24 Hours of Awareness
Medication errors All (regardless of whether 
associated with an AE)
Only if associated with an SAE
Medication errors include:

Medication errors involving participant exposure to the investigational product;

Potential medication errors or uses outside of what is foreseen in the protocol that do 
or do not involve the study participant.
Such medication errors occurring to a study participant are to be captured on the medication 
error page of the CRF, which is a specific version of the AE page.
In the event of a medication dosing error, the Sponsor should be notified within 24 hours.
Whether or not the medication error is accompanied by an AE, as determined by the 
Investigator, the medication error is recorded on the medication error page of the CRF and, if 
applicable, any associated AE(s), serious and nonserious, are recorded on an AE page of the 
CRF. 
Medication errors should be reported to Pfizer Safety within 24 hours on a CT SAE Report 
Form only when associated with an SAE.
8.4. Treatment of Overdose
For this study, any dose of fordadistrogene movaparvovec greater than a single 
administration of 2E14 vg/kg will be considered an overdose. Sponsor does not recommend 
specific treatment for an overdose.
In the event of an overdose, the Investigator/treating physician should:
1. Contact the medical monitor within 24 hours.
2. Closely monitor the participant for any AEs/SAEs and laboratory abnormalities for at 
least 34 calendar days after the overdose of fordadistrogene movaparvovec.
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3. Obtain a blood sample for pharmacokinetic (PK) analysis within [x] days from the 
date of the last dose of study intervention if requested by the medical monitor 
(determined on a case by case basis). Vector shedding will be assessed as a surrogate 
for PK. In Year 1 the assessment of vector shedding in whole blood is already 
planned for Day 2 (Visit 4), Day 4 (Visit 5), and Day 10 (Visit 10), and in the event 
of an overdose, additional assessments will be added on Day 1 (Visit 3) and Day 14 
(Visit 11). The assessment of vector shedding in saliva and urine will be done as 
planned. In Year 2, the same sampling schedule (whole blood, saliva and urine) for an 
overdose as in Year 1 will be followed. Both at Year 1 and Year 2, the sample 
collection for a particular matrix (sample type) will be stopped when at least 
2 consecutive negative results are observed in that matrix. 
4. Document the quantity of the excess dose as well as the duration of the overdose in 
the CRF.
5. Overdose is reportable to Safety only when associated with an SAE.
Decisions regarding dose interruptions or modifications will be made by the Investigator in 
consultation with the medical monitor based on the clinical evaluation of the participant.
8.5. Pharmacokinetics 
Pharmacokinetic parameters are not evaluated in this study. 
8.6. Pharmacodynamics
Pharmacodynamic parameters are not evaluated in this study.
8.7. Genetics
8.7.1. Specified Genetics
A blood sample for deoxyribonucleic acid (DNA) isolation may be collected. DNA samples 
will be analyzed for the purpose of confirming the diagnosis of DMD at Screening (Visit 1) 
by the central laboratory, if the Investigator determines that the results of the prior genetic 
test are inconclusive. 
Details on processes for collection and shipment of these samples can be found in Laboratory 
Manual.
8.7.2. Banked Biospecimens for Genetics
A 2-mL whole blood sample optimized for DNA isolation Prep D1.5 will be collected as 
local regulations and IRBs/ECs allow, if limits on blood volume collection have not been 
exceeded. 
Banked biospecimens may be used for research related to drug response and DMD. Genes 
and other analytes (eg, proteins, RNA, non-drug metabolites) may be studied using the 
banked samples. 
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Unless prohibited by local regulations or IRB/EC decision, participants will be asked to 
indicate on the consent document whether they will allow their banked biospecimens to also 
be used to design and conduct research in order to gain a further understanding of other 
diseases and to advance science, including development of other medicines for patients. This 
component of the sampling banking is optional for participants; they may still participate in 
the study even if they do not agree to the additional research on their banked biospecimens. 
The optional additional research does not require the collection of any further samples. 
See Appendix 5 for information regarding genetic research. Details on processes for 
collection and shipment of these samples can be found in Laboratory Manual.
8.8. Biomarkers
Collection of samples for biomarkers research is also part of this study.
8.8.1. Specified Gene Expression (RNA) Research
Specified gene expression (RNA) research is not included in this study.
8.8.2. Specified Protein Research
Specified protein research is not included in this study.
8.8.3. Specified Metabolomic Research 
Specified metabolomic research is not included in this study.
8.8.4. Banked Biospecimens for Biomarkers
A 1-mL whole blood (Prep B2.5), 1-mL whole blood (Prep B1.5), and 5-mL urine (Prep M4) 
samples will be collected as local regulations and IRB/ECs allow, if limits on blood volume 
collection have not been exceeded. 
Banked biospecimens may be used for research related to drug response and DMD. Genes 
and other analytes (eg, proteins, RNA, nondrug metabolites) may be studied using the banked 
samples. 
Unless prohibited by local regulations or IRB/EC decision, participants will be asked to 
indicate on the consent document whether they will allow their banked samples to also be 
used to design and conduct research in order to gain a further understanding of other diseases 
and to advance science, including development of other medicines for patients. This 
component of the sampling banking is optional for participants; they may still participate in 
the study even if they do not agree to the additional research on their banked samples. The 
optional additional research does not require the collection of any further samples.
See Appendix 5 for information regarding genetic research. Details on processes for 
collection and shipment of these samples can be found in Laboratory Manual. 
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8.8.5. Viral Vector Shedding Analysis
Whole blood (1.8 mL), saliva (4.2 mL), and urine (7.2 mL) samples for viral vector shedding 
kinetics will be collected in approximately the first 45 treated participants (approximately 
30 treated with fordadistrogene movaparvovec and approximately 15 treated with placebo). 
Potential visits at which samples are to be collected are detailed in the SoA. For each of the 
approximately first 45 treated participants, sample collection for a particular matrix (sample 
type) will be stopped when at least 2 consecutive negative results are observed in that matrix. 
An unblinded qualified Sponsor representative, independent and firewalled from the study 
team, will review the viral vector shedding results for each participant on an ongoing basis 
and will communicate with the sites when sampling in a given matrix for each participant 
should be stopped. The viral vector shedding results will not be shared with the sites. To 
maintain the study blind, the unblinded qualified Sponsor representative will select Cohort 2 
participants (as available) to also have the sampling of the same matrix stopped every time 
the sampling in a given matrix is stopped for a Cohort 1 participant. An attempt will be made 
to match these Cohort 2 participants to the specific matrix and timing of Cohort 1 
participants. 
Detailed collection, processing, storage, and shipment instructions will be provided in the 
central laboratory manual to maintain sample integrity for each sample type. 
The assay reflects the presence of DNA unique to fordadistrogene movaparvovec. Results 
below the lower limit of quantification (LLOQ) will be reported as below the limit of 
quantification (BLQ) and will be considered negative. Additionally, saliva and urine samples 
for all time points from a subset of participants will be analyzed for deoxyribonuclease-
resistant particles.
As part of understanding the disease and advance science, samples may be used for further 
characterization and/or evaluation. These data will be used for internal exploratory purposes 
and will not be included in the clinical study report. Samples collected for this purpose will 
be retained in accordance to local regulations and if not used, will be destroyed.
8.8.6. Study C3391007 Household Contact Immunogenicity
To further understand the development of antibodies to AAV9 (ie, seroconversion) due to 
household contact with a participant treated with fordadistrogene movaparvovec, a study may 
be performed under a separate protocol. Seroconversion rates from this separate study may 
be estimated prior to unblinding (either for an interim analysis or the primary analysis) of 
study C3391003. The integrity of the C3391003 study blind will be maintained by the use of 
an independent, external team of statistician(s) and programmer(s) to estimate the 
seroconversion rates. Only summary seroconversion rates will be communicated.
8.9. Health Economics
8.9.1. Healthcare Resource Utilization Questionnaire – Caregiver (HRU:CG)
The Healthcare Resource Use questionnaire is a 4-item, caregiver-completed measure that 
asks about healthcare resource utilization related to their child’s use of healthcare 
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professionals, emergency room visits, and hospitalizations related to DMD. Caregivers are 
also asked to estimate out-of-pocket costs related to healthcare resource utilization. The 
recall period is the past 3 months.
8.9.2. Work Productivity and Activity Impairment DMD Questionnaire – Caregiver 
(WPAI:DMD Caregiver)
The WPAI:DMD Caregiver is a 6-item, caregiver-completed questionnaire that measures the 
effect of a child being diagnosed with DMD on caregiver work productivity and impairment. 
The WPAI:DMD Caregiver yields four scores: absenteeism (work time missed); 
presenteeism (impairment at work/reduced on the job effectiveness); work productivity loss 
(overall work impairment/absenteeism plus presenteeism); and activity impairment. Each 
score is expressed as a percentage (0-100%) with higher numbers indicating greater 
impairment and less productivity (Reilly et al, 1993).65 The recall period is the past 7 days.
8.10. Immunogenicity
8.10.1. Neutralizing Antibody to AAV9
Blood samples for analysis of NAb to AAV9 will be collected. Detailed collection, 
processing, storage, and shipment instructions will be provided in the central laboratory 
manual.
Samples will be analyzed using validated analytical methods in compliance with Pfizer 
standard operating procedures (SOP). 
As part of understanding of the immunogenicity of the fordadistrogene movaparvovec, 
samples may be used for further characterization and/or evaluation of the bioanalytical 
method. These data will be used for internal exploratory purposes and will not be included in 
the clinical report. Samples collected for this purpose will be retained in accordance to local 
regulations and if not used, will be destroyed.
8.10.2. ELISpot
Blood samples to provide peripheral blood mononuclear cells for analysis of cellular immune 
responses to mini-dystrophin and AAV9 will be collected. 
Detailed collection, processing, storage, and shipment instructions are provided in the central 
laboratory manual. 
As part of understanding of the immunogenicity of fordadistrogene movaparvovec, samples 
may be used for further characterization and/or evaluation of the bioanalytical method. In 
addition, residual of these samples may be used for the evaluation of exploratory biomarkers 
of immune response. These data will be used for internal exploratory purposes and will not 
be included in the clinical report. Samples collected for this purpose will be retained in 
accordance to local regulations and if not used, will be destroyed. 
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8.10.3. Anti-drug Antibodies 
Blood samples for analysis of anti-transgene (mini-dystrophin) and anti-AAV9 antibodies 
will be collected. However, these will only be tested if clinically indicated (eg, clinical 
immune response to fordadistrogene movaparvovec).
Detailed collection, processing, storage, and shipment instructions will be provided in the 
central laboratory manual. 
Samples will be analyzed using validated analytical methods in compliance with Pfizer 
standard operating procedures.
As part of understanding of the immunogenicity of the fordadistrogene movaparvovec, 
samples may be used for further characterization and/or evaluation of the bioanalytical 
method. These data will be used for internal exploratory purposes and will not be included in 
the clinical report. Samples collected for this purpose will be retained in accordance to local 
regulations and if not used, will be destroyed.
9. STATISTICAL CONSIDERATIONS
Detailed methodology for summary and statistical analyses of the data collected in this study 
is outlined here and further detailed in a statistical analysis plan (SAP), which will be 
maintained by the Sponsor. The SAP may modify what is outlined in the protocol where 
appropriate; however, any major modifications of the primary endpoint definitions or their 
analyses will also be reflected in a protocol amendment.
9.1. Estimands and Statistical Hypotheses
For the primary endpoint, the null hypothesis is that there is no difference between 
fordadistrogene movaparvovec and placebo with respect to mean change from Baseline at 
Week 52 in the NSAA total score. The alternative hypothesis is that fordadistrogene 
movaparvovec is different from placebo with respect to mean change from Baseline at Week 
52 in the NSAA total score. 
The experiment-wise Type I error of =0.05 (two-sided) will be controlled using gatekeeping 
and fixed-sequence procedures for the primary and select secondary endpoints listed below. 
The hypotheses for the secondary endpoints are similar to those for the primary endpoint. 
1. Change from Baseline at Week 52 in the 10 meter run/walk velocity.
2. Change from Baseline at Week 52 in the rise from floor velocity.
3. Number of skills either improved or maintained at Week 52 based on the individual 
items of the NSAA.
4. Number of skills gained at Week 52 based on the individual items of the NSAA.
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If the null hypothesis for the primary endpoint is rejected, statistical testing proceeds to the 
hypotheses for the secondary endpoints; otherwise, formal statistical testing in the sense of 
controlling the experiment-wise Type I error stops and nominal p-values for secondary 
endpoints will be reported and interpreted accordingly. 
The secondary endpoints will be tested in the order specified above. To maintain the study-
wise type 1 error rate, the p-value boundary for these secondary endpoint analyses will be the 
same as the primary analysis as detailed in the Interim Analysis SAP.. If the null hypothesis 
for the first endpoint in the sequence is rejected, statistical testing moves to the next endpoint 
in the sequence. Statistical testing proceeds to subsequent endpoints in the sequence only if 
the null hypothesis for the previous endpoint is rejected. If a null hypothesis in the sequence 
is not rejected, formal statistical testing in the sense of controlling the experiment-wise 
Type I error is stopped for all endpoints later in the sequence and nominal p-values will be 
reported and interpreted accordingly.
The null hypothesis for the primary and secondary endpoints will be tested at Week 52 using 
the parameter and variance estimates from the MMRM model or the generalized mixed 
model described in Section 9.4.1. 
If either interim analysis is performed, a group sequential approach will be applied to the 
efficacy analyses to control Type I error across the interim analysis/analyses and the primary 
analysis. Specifically, a gamma family alpha-spending function with gamma parameter -1 
will be used. Additionally, an assessment of futility (non-blinding) based on the primary 
endpoint will be made at each interim analysis, if performed, using a gamma family spending 
function with gamma parameter -4.
9.1.1. Estimands
Primary Estimand: This estimand will be the primary estimand and will be the difference in 
mean change from Baseline at Week 52 in the NSAA total score between fordadistrogene 
movaparvovec and placebo regardless of adherence to background and protocol-mandated 
glucocorticoid regimens (see Section 6.5.1) during the first 52 weeks: 

Population: Boys with a genetic diagnosis of DMD who are ambulatory and age ≥4 to 
<8 years;

Variable: Change from Baseline at Week 52 in the NSAA total score;

Death or loss of ambulation are identified as potential intercurrent events. Details on 
how these intercurrent events are handled in the analysis are provided in the SAP

Population-level summary: Difference in mean changes from Baseline at Week 52 in 
the NSAA total score between fordadistrogene movaparvovec and placebo.
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9.2. Sample Size Determination
A sufficient number of participants will be screened to achieve a total of approximately 
99 participants in the FAS (see Section 9.3). Participants will be randomly assigned in a 2:1 
fashion to Cohort 1 (approximately 66 participants) or Cohort 2 (approximately 33 
participants) across the two strata (age <6 years and age ≥6 years). This sample size is based 
on the primary efficacy endpoint of change from Baseline at Week 52 in the NSAA total 
score. The above sample size (assuming 3 participants will drop out of the study prior to 
Week 52) will provide 98% power to detect a treatment difference (fordadistrogene 
movaparvovec – placebo) of 3.0. These calculations are based on =0.05 (two-sided), a 
common standard deviation of 3.5 and using the normal approximation of the test statistic for 
the comparison between two means. Assuming both interim analyses will be performed (3 
looks) and a gamma family alpha-spending function with gamma parameter -1 for efficacy 
will be used to control Type I error, the probability of crossing the boundary at the first 
interim analysis is 38%, at the second interim analysis is 78%, and at the primary analysis is 
97%. A gamma family spending function with gamma parameter -4 will be used for the non-
blinding futility boundary.
9.3. Populations for Analysis
For purposes of analysis, the following populations are defined:
Population
Description
Enrolled 
All participants who sign the Informed Consent Document.
Randomly assigned to 
investigational product
All participants, excluding siblings, who were randomly assigned to 
Cohort 1 (initially fordadistrogene movaparvovec) or Cohort 2 (initially 
placebo).
Full Analysis Set (FAS) 
(through Week 52)a
All participants, excluding siblings and those meeting exclusion criterion 
15, who were randomly assigned and received a single dose of IP on 
Day 1 (Year 1 Day 1). Participants will be analyzed according to the 
cohort to which they were randomized.
Safety Analysis Set (through 
Week 52)
All participants, including siblings and those meeting exclusion criterion 
15, who were randomly assigned and received a single dose of IP on 
Day 1 (Year 1 Day 1). Participants will be analyzed according to the IP 
they actually received.
Efficacy Analysis Set (long-
term)
All participants, including siblings, but excluding those meeting protocol 
exclusion criteria 15, who received a single dose of fordadistrogene 
movaparvovec (either at Year 1 or Year 2). 
Safety Analysis Set (Cohort 2 
delayed treatment) 
All participants, including siblings, who received a single dose of 
fordadistrogene movaparvovec on Day 390 (Year 2 Day 1).
Safety Analysis Set (long-
term)
All participants, including siblings and those meeting exclusion criterion 
15, who received a single dose of fordadistrogene movaparvovec (either 
at Year 1 or Year 2).
a Of note, per the PCD definition in Sections 4.1 and 9.5, the primary analysis will occur after at least 90 FAS 
participants complete Day 360 (Visit 19) or discontinue from the study prior to Week 52 if they had received Year 1 
IP at least one year prior to the data cutoff.
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9.4. Statistical Analyses
The SAP will be developed and finalized before database lock and will describe all planned 
statistical analyses including the participant populations to be included in the analyses and 
procedures for accounting for missing, unused, and spurious data. This section is a summary 
of the planned statistical analyses of the primary and secondary endpoints.
9.4.1. Efficacy Analyses
Endpoint
Statistical Analysis Methods
Primary
Inferential testing for the primary analysis for the primary endpoint will be performed 
at =0.05 (two-sided).
Baseline NSAA total score is defined as the last non-missing NSAA total score 
collected prior to Year 1 IP administration.
Primary analysis: Change from Baseline at Week 52 in the NSAA total score will be 
analyzed using a mixed model repeated measures approach including visits 
through Week 52 where NSAA is assessed. The analysis will be based on the 
FAS (Regardless of adherence to glucocorticoid regimen) and missing data will 
not be explicitly imputed. The model will include fixed effects for treatment 
(class variable), visit (class variable), treatment by visit interaction, Baseline 
NSAA total score (continuous variable), Screening age (continuous variable), 
Baseline NSAA total score by visit interaction, and Screening age by visit 
interaction with an unstructured covariance matrix to describe the correlation 
among different visits from the same participant. Alternative covariance 
structures to address any issues with model convergence will be specified in the 
SAP. To test the null hypothesis, estimates at Week 52 of the mean changes from 
Baseline and 95% confidence intervals along with the mean treatment group 
difference, two-sided p-value, and two-sided 95% confidence interval for the 
mean difference will be provided.
Sensitivity analyses to assess the effect of missing data will be described in the SAP.
Secondary
Inferential testing of the secondary endpoints will be performed as described in 
Section 9.1.
Baseline is defined as the last non-missing assessment collected prior to Year 1 IP 
administration.
The following endpoints will be analyzed using an analysis of covariance model 
including model terms for treatment group, Baseline (continuous variable), and 
Screening age (continuous variable).

Change from Baseline in percent normal mini-dystrophin expression level in 
biceps brachii muscle biopsies at Day 360 using LC-MS assay.

Change from Baseline in percent of muscle fibers expressing mini-dystrophin 
in biceps brachii muscle biopsies at Day 360 as assessed by 
immunofluorescence.
Change from Baseline at Week 52 in serum CK concentration will be analyzed using a 
mixed model repeated measures approach and a log transformation. The model 
fixed effects will be similar to those in the primary endpoint analysis and visits 
through Week 52 where serum CK concentration is assessed will be included.
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Endpoint
Statistical Analysis Methods
The below two endpoints will be analyzed using a generalized mixed model assuming 
a binomial distribution and a logit link. The model terms will include treatment 
and Screening age (continuous variable). 

Number of skills gained at Week 52 based on the individual items of the 
NSAA. For each individual item, a gained skill is defined as a score of 0 at 
Baseline and a score of 1 or 2 at Week 52.

Number of skills either improved or maintained at Week 52 compared to 
Baseline based on the individual items of the NSAA. For each individual 
item, an improved or maintained skill is defined as a score of 0 at Baseline 
and a score of 1 or 2 at Week 52, a score of 1 at Baseline and a score of 2 at 
Week 52, a score of 1 at Baseline and a score of 1 at Week 52, or a score of 2 
at Baseline and a score of 2 at Week 52.
The following endpoints will be analyzed using a similar mixed model repeated 
measures approach as used for the primary analysis.

Change from Baseline at Week 52 in the 10 meter run/walk velocity; 

Change from Baseline at Week 52 in the rise from floor velocity;

Change from Baseline at Week 52 in the Modified PODCI: Transfer and 
Basic Mobility Core Scale (Pediatric Parent);

Change from Baseline at Week 52 in the Modified PODCI: Sports and 
Physical Functioning Core Scale (Pediatric Parent).
Exploratory
Analyses for the exploratory endpoints defined in Section 3.1 will be described in the 
SAP.
As a general rule, all efficacy analyses including analysis of the primary endpoint, secondary endpoints, and other 
endpoints will be conducted based on FAS participants regardless of adherence to background or protocol mandated 
glucocorticoid regimens during the first 52 weeks after study drug infusion, unless specified otherwise.
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9.4.2. Safety Analyses
All safety analyses will be performed on the safety population.
Statistical Analysis Methods
Descriptive summaries through Week 52 will be provided by treatment group for participants in the 
Safety (through Week 52) population for the following:

Incidence, severity, and causal relationship of TEAEs (AEs and SAEs);

Incidence of abnormal laboratory findings and magnitude of change;

Abnormal and clinically relevant changes in:

Physical exam;

Neurological exam;

Weight;

Vital signs;

ECG;

Echocardiogram;

Cardiac MRI;

CBCL.
Descriptive summaries relative to pre-fordadistrogene movaparvovec baseline through Year 2 Week 52 
for participants in the Safety (Cohort 2 delayed treatment) population will be provided for the above 
safety parameters.
Descriptive summaries relative to pre-fordadistrogene movaparvovec baseline through 5 years post 
fordadistrogene movaparvovec administration for participants in the Safety (long-term) population will 
be provided for the above safety parameters for combined Cohorts 1 and 2.
9.4.2.1. Electrocardiogram Analyses
Changes from Baseline through Week 52 for the ECG parameters QT interval, heart rate, 
QTc interval, PR interval, and QRS complex will be summarized by treatment and time. 
Changes in the above ECG parameters from pre-fordadistrogene movaparvovec baseline to 
Year 2 Week 52 for participants in Cohort 2 and at 1, 2, 3, 4 and 5 years post fordadistrogene 
movaparvovec administration will be summarized.
9.5. Interim Analyses
There are 2 options for interim analyses, both of which are designed to provide data to 
support an earlier regulatory submission for BLA/MAA based on the primary endpoint of 
change from Baseline at Week 52 in the NSAA total score. The objective of each interim 
analysis is to demonstrate a statistically significant effect of fordadistrogene movaparvovec 
on the primary endpoint of change from Baseline at Week 52 in the NSAA total score 
compared to placebo. Additionally, an assessment of futility (non-binding) based on the 
primary endpoint will be made at each interim analysis, if performed.
The first interim analysis may be performed when approximately 30 participants in the FAS 
have completed visits through Week 52, and the second interim may be performed when 
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approximately 60 participants in the FAS have completed visits through Week 52. The 
decision to conduct either interim analysis will be based on regulatory feedback, study 
recruitment rates and emerging data from other studies in the program. The objectives, 
estimands, endpoints, and analysis method for each interim analysis are identical to the 
primary analysis (Section 9.4.1). If either interim analysis is performed, a group sequential 
approach will be applied to the efficacy analyses to control Type I error across the interim 
analysis/analyses and the primary analysis. Specifically, a gamma family alpha-spending 
function with gamma parameter -1 will be used. Additionally, an assessment of futility (non-
binding) based on the primary endpoint will be made at each interim analysis, if performed, 
using a gamma family spending function with gamma parameter -4.
Before any interim analysis is implemented, the details of the objectives, decision criteria 
(based on the actual number of participants and the number of looks), dissemination plan, 
method of maintaining the study blind, and analysis details will be recorded in the 
appropriate study documents. The interim analysis/analyses will be performed by an 
independent team of statisticians and programmers, and the results will be unblinded only to 
the E-DMC and/or a limited number of individuals within the Sponsor organization who are 
not involved in the conduct or further analysis of the ongoing study. These unblinded 
individuals from the Sponsor organization will be responsible for reviewing the results from 
the interim analyses and making a recommendation on pursuing a regulatory submission 
based on the interim analysis results. 
The timing of public disclosure of the results of either interim analysis will be at the 
discretion of the Sponsor. If disclosure of interim analysis results prior to completion of the 
C3391003 trial is believed to have the potential to interfere with study completion, the 
Sponsor may choose to delay disclosure of the interim analysis until the trial has completed. 
Irrespective of whether an interim analysis has been conducted, the primary analysis will 
occur after at least 90 FAS participants complete Day 360 (Visit 19) or discontinue from the 
study prior to Week 52, if they had received Year 1 IP at least one year prior to the data 
cutoff. . After the database has been released for the primary analysis, the study may become 
fully unblinded. If either an interim analysis is performed and the objectives are not met, the 
nominal type I error for the primary analysis will be adjusted accordingly. If either interim 
analysis is performed and the objective is met, the primary analysis at Week 52 will primarily 
be used to provide a more precise estimate of the treatment difference for the primary 
endpoint.
Additional analyses may be performed after the primary analysis, as needed, per regulatory 
requirements or in support of publications. 
9.5.1. Data Monitoring Committee 
This study will use an external data monitoring committee (E-DMC). 
The E-DMC will be responsible for ongoing monitoring of the efficacy and safety of 
participants in the study according to the charter. The recommendations made by the E-DMC 
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to alter the conduct of the study will be forwarded to Pfizer for final decision. Pfizer will 
forward such decisions, which may include summaries of aggregate analyses of endpoint 
events and of safety data that are not endpoints, to regulatory authorities, as appropriate.
In the event of a serious safety issue, the Sponsor may determine that screening, 
randomization, and/or dosing are paused until the E-DMC reviews the relevant data and 
makes recommendations for the study conduct.
 
 
 
 Additional details on the E-DMC 
responsibilities can be found in the E-DMC Charter. The Sponsor will adhere to related local 
regulatory reporting requirements. If the trial is temporarily halted (screening, randomization, 
and/or dosing) by the Sponsor due to a safety concern (eg, in the event of a serious safety 
issue) the temporary halt notification must be submitted to the regulatory authorities within 
the regulatory timelines set in the current applicable regulations, and the trial restart will be 
only possible after regulatory approval via a substantial amendment, if needed.
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10. SUPPORTING DOCUMENTATION AND OPERATIONAL CONSIDERATIONS
10.1. Appendix 1: Regulatory, Ethical, and Study Oversight Considerations
10.1.1. Regulatory and Ethical Considerations
This study will be conducted in accordance with the protocol and with the following:

Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and CIOMS International Ethical Guidelines;

Applicable ICH GCP guidelines;

Applicable laws and regulations, including applicable privacy laws.
The protocol, protocol amendments, ICD, SRSDs, and other relevant documents (eg, 
advertisements) must be reviewed and approved by the sponsor, and submitted to an IRB/EC 
by the investigator, and reviewed and approved by the IRB/EC before the study is initiated.
Any amendments to the protocol will require IRB/EC approval before implementation of 
changes made to the study design, except for changes necessary to eliminate an immediate 
hazard to study participants.
Protocols and any substantial amendments to the protocol will require health authority 
approval prior to initiation except for changes necessary to eliminate an immediate hazard to 
study participants.
The investigator will be responsible for the following:

Providing written summaries of the status of the study to the IRB/EC annually or 
more frequently in accordance with the requirements, policies, and procedures 
established by the IRB/EC;

Notifying the IRB/EC of SAEs or other significant safety findings as required by 
IRB/EC procedures;

Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR, ICH GCP guidelines, the IRB/EC, European regulation 
536/2014 for clinical studies, European Medical Device Regulation 2017/745 for 
clinical device research, and all other applicable local regulations.
10.1.1.1. Reporting of Safety Issues and Serious Breaches of the Protocol or ICH GCP
In the event of any prohibition or restriction imposed (ie, clinical hold) by an applicable 
regulatory authority in any area of the world, or if the Investigator is aware of any new 
information that might influence the evaluation of the benefits and risks of the study 
intervention, Pfizer should be informed immediately. Investigators in Japan should see 
Section 10.10 (Appendix 10).
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In addition, the investigator will inform Pfizer immediately of any urgent safety measures 
taken by the investigator to protect the study participants against any immediate hazard, and 
of any serious breaches of this protocol or of ICH GCP that the investigator becomes aware 
of.
10.1.2. Financial Disclosure
Investigators and subinvestigators will provide the Sponsor with sufficient, accurate financial 
information as requested to allow the Sponsor to submit complete and accurate financial 
certification or disclosure statements to the appropriate regulatory authorities. Investigators 
are responsible for providing information on financial interests during the course of the study 
and for 1 year after completion of the study.
10.1.3. Informed Consent Process 
The investigator or their representative will explain the nature of the study to the participant 
and their parent(s)/legal guardian and answer all questions regarding the study. The 
participant and their parent(s)/legal guardian should be given sufficient time and opportunity 
to ask questions and to decide whether or not to participate in the trial.
When consent is obtained from a participant’s parent(s)/legal guardian, the participant’s 
assent (affirmative agreement) must be subsequently obtained when the participant has the 
capacity to provide assent, as determined by the IRB/EC. If the investigator determines that a 
participant’s decisional capacity is so limited they cannot reasonably be consulted, then, as 
permitted by the IRB/EC and consistent with local regulatory and legal requirements, the 
participant’s assent may be waived with source documentation of the reason assent was not 
obtained. If the study participant does not provide their own assent, the source documents 
must record why the participant did not provide assent (for example, the child is not of 
assenting age per local regulations or policies), how the investigator determined that the 
person signing the consent was the participant’s parent(s)/legal guardian, the consent signer’s 
relationship to the study participant, and that the participant’s assent was obtained or 
waived. If assent is obtained verbally, it must be documented in the source documents.
If study participants are minors who reach the age of majority or if a child reaches the age of 
assent (per local IRB/EC requirements) during the study, as recognized under local law, the 
child or adolescent must then provide the appropriate assent or consent to document their 
willingness to continue in the study. For an adolescent who reaches the age of consent, 
parental consent would no longer be valid. If the enrollment of emancipated minors is 
permitted by the IRB/EC and local law, the participant must provide documentation of legal 
status to give consent without the permission of a legally authorized representative.
Participants and their parent(s)/legal guardian must be informed that their participation is 
voluntary. The participant’s parent(s)/legal guardian will be required to sign a statement of 
informed consent that meets the requirements of 21 CFR 50, local regulations, ICH 
guidelines, HIPAA requirements, where applicable, and the IRB/EC or study center.
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The investigator must ensure that each study participant’s parent(s)/legal guardian and the 
study participant as applicable are fully informed about the nature and objectives of the 
study, the sharing of data related to the study, and possible risks associated with 
participation, including the risks associated with the processing of the participant’s personal 
data. 
The participant’s parent(s)/legal guardian must be informed that the participant’s personal 
study-related data will be used by the sponsor in accordance with local data protection law. 
The level of disclosure must also be explained to the participant’s parent(s)/legal guardian.
The participant’s parent(s)/legal guardian must be informed that the participant’s medical 
records may be examined by Clinical Quality Assurance auditors or other authorized 
personnel appointed by the sponsor, by appropriate IRB/EC members, and by inspectors 
from regulatory authorities.
The investigator further must ensure that each study participant’s parent(s)/legal guardian is 
fully informed about their right to access and correct their child’s personal data and to 
withdraw consent for the processing of their child’s personal data, keeping in mind the 
privacy rights that may restrict access of older adolescents’ medical records by their 
parent(s)/legal guardian in certain regions.
The source documentation must include a statement that written informed consent, and as 
applicable, assent was obtained before the participant was enrolled in the study and the date 
the written consent/assent was obtained. The authorized person obtaining the informed 
consent must also sign the ICD.
Parent(s)/legal guardian and the participant must be reconsented to the most current version 
of the ICD(s)/assent during their participation in the study as required per local regulations.
A copy of the ICD(s) and assent, if written, must be provided to the parent(s)/legal guardian 
and the participant.
Participants who are rescreened are required to sign a new ICD. 
10.1.4. Data Protection
All parties will comply with all applicable laws, including laws regarding the implementation 
of organizational and technical measures to ensure protection of participant data.
Participants’ personal data will be stored at the study site in encrypted electronic and/or paper 
form and will be password protected or secured in a locked room to ensure that only 
authorized study staff have access. The study site will implement appropriate technical and 
organizational measures to ensure that the personal data can be recovered in the event of 
disaster. In the event of a potential personal data breach, the study site will be responsible for 
determining whether a personal data breach has in fact occurred and, if so, providing breach 
notifications as required by law.
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To protect the rights and freedoms of participants with regard to the processing of personal 
data, participants will be assigned a single, participant-specific numerical code. Any 
participant records or data sets that are transferred to the sponsor will contain the numerical 
code; participant names will not be transferred. All other identifiable data transferred to the 
sponsor will be identified by this single, participant-specific code. The study site will 
maintain a confidential list of participants who participated in the study, linking each 
participant’s numerical code to their actual identity and medical record ID. In case of data 
transfer, the sponsor will protect the confidentiality of participants’ personal data consistent 
with the clinical study agreement and applicable privacy laws.
Information technology systems used to collect, process, and store study-related data are 
secured by technical and organizational security measures designed to protect such data 
against accidental or unlawful loss, alteration, or unauthorized disclosure or access.
The sponsor maintains SOPs on how to respond in the event of unauthorized access, use, or 
disclosure of sponsor information or systems.
10.1.5. Dissemination of Clinical Study Data
Pfizer fulfills its commitment to publicly disclose clinical study results through posting the 
results of studies on www.clinicaltrials.gov (ClinicalTrials.gov), the EudraCT, and/or 
www.pfizer.com, and other public registries in accordance with applicable local 
laws/regulations. In addition, Pfizer reports study results outside of the requirements of local 
laws/regulations pursuant to its SOPs.
In all cases, study results are reported by Pfizer in an objective, accurate, balanced, and 
complete manner and are reported regardless of the outcome of the study or the country in 
which the study was conducted.
www.clinicaltrials.gov
Pfizer posts clinical trial results on www.clinicaltrials.gov for Pfizer-sponsored interventional 
studies (conducted in patients) that evaluate the safety and/or efficacy of a product, 
regardless of the geographical location in which the study is conducted. These results are 
submitted for posting in accordance with the format and timelines set forth by US law.
EudraCT/CTIS
Pfizer posts clinical trial results on EudraCT/CTIS for Pfizer-sponsored interventional studies 
in accordance with the format and timelines set forth by EU requirements.
www.pfizer.com
Pfizer posts CSR synopses and plain-language study results summaries on www.pfizer.com 
for Pfizer-sponsored interventional studies at the same time the corresponding study results 
are posted to www.clinicaltrials.gov. CSR synopses will have personally identifiable 
information anonymized.
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Documents within marketing applications
Pfizer complies with applicable local laws/regulations to publish clinical documents included 
in marketing applications. Clinical documents include summary documents and CSRs 
including the protocol and protocol amendments, sample CRFs, and SAPs. Clinical 
documents will have personally identifiable information anonymized.
Data Sharing
Pfizer provides researchers secure access to participant-level data or full CSRs for the 
purposes of “bona-fide scientific research” that contributes to the scientific understanding of 
the disease, target, or compound class. Pfizer will make data from these trials available 
18 months after study completion. Participant-level data will be anonymized in accordance 
with applicable privacy laws and regulations. CSRs will have personally identifiable 
information anonymized.
Data requests are considered from qualified researchers with the appropriate competencies to 
perform the proposed analyses. Research teams must include a biostatistician. Data will not 
be provided to applicants with significant conflicts of interest, including individuals 
requesting access for commercial/competitive or legal purposes.
10.1.6. Data Quality Assurance
All participant data relating to the study will be recorded on printed or electronic CRF unless 
transmitted to the sponsor or designee electronically (eg, laboratory data). The investigator is 
responsible for verifying that data entries are accurate and correct by physically or 
electronically signing the CRF.
Guidance on completion of CRFs will be provided in the CRF Completion Requirements 
document. 
The investigator must ensure that the CRFs are securely stored at the study site in encrypted 
electronic and/or paper form and are password protected or secured in a locked room to 
prevent access by unauthorized third parties.
The investigator must permit study-related monitoring, audits, IRB/EC review, and 
regulatory agency inspections and provide direct access to source records and documents. 
This verification may also occur after study completion. It is important that the 
investigator(s) and their relevant personnel are available during the monitoring visits and 
possible audits or inspections and that sufficient time is devoted to the process.
Monitoring details describing strategy, including definition of study-critical data items and 
processes (eg, risk based initiatives in operations and quality such as risk management and 
mitigation strategies and analytical risk based monitoring), methods, responsibilities, and 
requirements, including handling of noncompliance issues and monitoring techniques 
(central, virtual, or on site monitoring), are provided in the data management plan and 
monitoring plan maintained and utilized by the sponsor or designee.
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The sponsor or designee is responsible for the data management of this study, including 
quality checking of the data.
Records and documents, including signed ICDs, pertaining to the conduct of this study must 
be retained by the investigator for 15 years after study completion unless local regulations or 
institutional policies require a longer retention period. No records may be destroyed during 
the retention period without the written approval of the sponsor. No records may be 
transferred to another location or party without written notification to the sponsor. The 
investigator must ensure that the records continue to be stored securely for as long as they are 
maintained.
When participant data are to be deleted, the investigator will ensure that all copies of such 
data are promptly and irrevocably deleted from all systems.
The investigator(s) will notify the sponsor or its agents immediately of any regulatory 
inspection notification in relation to the study. Furthermore, the investigator will cooperate 
with the sponsor or its agents to prepare the investigator site for the inspection and will allow 
the sponsor or its agent, whenever feasible, to be present during the inspection. The 
investigator site and investigator will promptly resolve any discrepancies that are identified 
between the study data and the participant's medical records. The investigator will promptly 
provide copies of the inspection findings to the sponsor or its agent. Before response 
submission to the regulatory authorities, the investigator will provide the sponsor or its 
agents with an opportunity to review and comment on responses to any such findings.
10.1.7. Source Documents
Source documents provide evidence for the existence of the participant and substantiate the 
integrity of the data collected. Source documents are filed at the Investigator site. In most 
cases, the source documents are the hospital or the physician subject chart. In some cases, the 
CRF may also serve as the source document. In these cases, a document should be available 
at the investigator site and at Pfizer that clearly identifies those data that will be recorded on 
the CRF, and for which the CRF will stand as the source document.
Data reported on the CRF or entered in the electronic CRF (eCRF) that are transcribed from 
source documents must be consistent with the source documents or the discrepancies must be 
explained. The Investigator may need to request previous medical records or transfer records, 
depending on the study. Also, current medical records must be available.
10.1.8. Use of Medical Records
In certain situations, sponsor review of redacted copies of participant medical records for 
local laboratory test results may be performed, where ethically and scientifically justified and 
permitted by local regulations, to ensure participant safety. 
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Due to the potential for a participant to be re-identified from their medical records, the 
following actions must be taken when medical records are sent to the sponsor or sponsor 
designee:

The investigator or site staff must redact personal information from the medical 
record. The personal information includes, but is not limited to, the following: 
participant names or initials, participant dates (eg, birth date, date of hospital 
admission/discharge, date of death), participant identification numbers (eg, Social 
Security number, health insurance number, medical record number, 
hospital/institution identifier), participant location information (eg, street address, 
city, country, postal code, IP address), participant contact information (eg, 
telephone/fax number, email address).

Each medical record must be transmitted to the sponsor or sponsor designee using 
systems with technical and organizational security measures to ensure the protection 
of personal data (eg, Florence is the preferred system if available). 

There may be unplanned situations where the sponsor may request medical records 
(eg, sharing medical records so that the sponsor can provide study-related advice to 
the investigator). The medical records should be submitted according to the procedure 
described above. 
10.1.9. Study and Site Start and Closure
The study start date is the date of the first participant’s first visit.
The sponsor designee reserves the right to close the study site or terminate the study at any 
time for any reason at the sole discretion of the sponsor, including (but not limited to) 
regulatory authority decision, change in opinion of the IRB/EC, or change in benefit-risk 
assessment. Study sites will be closed upon study completion. A study site is considered 
closed when all required documents and study supplies have been collected and a study-site 
closure visit has been performed.
The investigator may initiate study-site closure at any time upon notification to the CRO if 
requested to do so by the responsible IRB/EC or if such termination is required to protect the 
health of study participants.
Reasons for the early closure of a study site by the Sponsor may include but are not limited 
to:

Failure of the investigator to comply with the protocol, the requirements of the 
IRB/EC or local health authorities, the Sponsor's procedures, or GCP guidelines;

Inadequate recruitment of participants by the investigator;

Discontinuation of further study intervention development.
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If the study is prematurely terminated or suspended, the sponsor shall promptly inform the 
investigators, the ECs/IRBs, the regulatory authorities, and any CRO(s) used in the study of 
the reason for termination or suspension, as specified by the applicable regulatory 
requirements. The investigator shall promptly inform the participant and should assure 
appropriate participant therapy and/or follow-up.
If the sponsor decides to terminate the study for a reason unrelated to the safety of study 
intervention(s), protocol-specified safety assessments will continue to be performed for these 
participants until the end of the study as defined in Sections 4.4.
Study termination is also provided for in the clinical study agreement. If there is any conflict 
between the contract and this protocol, the contract will control as to termination rights.
10.1.10. Publication Policy
For multicenter trials, the primary publication will be a joint publication developed by the 
investigator and Pfizer reporting the primary endpoint(s) of the study covering all study sites. 
The investigator agrees to refer to the primary publication in any subsequent publications. 
Pfizer will not provide any financial compensation for the investigator’s participation in the 
preparation of the primary congress abstract, poster, presentation, or primary manuscript for 
the study.
Investigators are free to publish individual center results that they deem to be clinically 
meaningful after publication of the overall results of the study or 12 months after primary 
completion date or study completion at all sites, whichever occurs first, subject to the other 
requirements described in this section.
The investigator will provide Pfizer an opportunity to review any proposed publication or 
any other type of disclosure of the study results (collectively, “publication”) before it is 
submitted or otherwise disclosed and will submit all publications to Pfizer 30 days before 
submission. If any patent action is required to protect intellectual property rights, the 
investigator agrees to delay the disclosure for a period not to exceed an additional 60 days 
upon request from Pfizer. This allows Pfizer to protect proprietary information and to provide 
comments, and the investigator will, on request, remove any previously undisclosed 
confidential information before disclosure, except for any study-intervention or  
Pfizer-related information necessary for the appropriate scientific presentation or 
understanding of the study results. For joint publications, should there be disagreement 
regarding interpretation and/or presentation of specific analysis results, resolution of, and 
responsibility for, such disagreements will be the collective responsibility of all authors of 
the publication.
For all publications relating to the study, the Investigator and Pfizer will comply with 
recognized ethical standards concerning publications and authorship, including those 
established by the International Committee of Medical Journal Editors. The investigator will 
disclose any relationship with Pfizer and any relevant potential conflicts of interest, including 
any financial or personal relationship with Pfizer, in any publications. All authors will have 
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access to the relevant statistical tables, figures, and reports (in their original format) required 
to develop the publication.
10.1.11. Sponsor’s Qualified Medical Personnel
The contact information for the Sponsor's appropriately qualified medical personnel for the 
study is documented in the study contact list located in the supporting study documentation 
provided by the Sponsor. 
To facilitate access to appropriately qualified medical personnel on study-related medical 
questions or problems, participants are provided with a contact card. The contact card 
contains, at a minimum, protocol and investigational product identifiers, participant numbers, 
contact information for the Investigator site, and contact details for a contact center in the 
event that the Investigator site staff cannot be reached to provide advice on a medical 
question or problem originating from another healthcare professional not involved in the 
participant’s participation in the study. The contact number can also be used by Investigator 
staff if they are seeking advice on medical questions or problems; however, it should be used 
only in the event that the established communication pathways between the Investigator site 
and the study team are not available. It is therefore intended to augment, but not replace, the 
established communication pathways between the Investigator site and the study team for 
advice on medical questions or problems that may arise during the study. The contact number 
is not intended for use by the participant directly, and if a participant calls that number, he 
will be directed back to the Investigator site.
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10.2. Appendix 2: Clinical Laboratory Tests
The following safety laboratory tests will be performed at times defined in the SoA section of 
this protocol. Additional laboratory results may be reported on these samples as a result of 
the method of analysis or the type of analyzer used by the clinical laboratory; or as derived 
from calculated values. These additional tests would not require additional collection of 
blood. Unscheduled clinical laboratory measurements may be obtained at any time during the 
study to assess any perceived safety concerns.
Table 3.
Protocol Required Safety Laboratory Assessments
CENTRAL LABORATORY TESTING
Clinical Safety
Hematology
Urinalysis
Other
Hemoglobin
Hematocrit
Red blood cell (RBC) count and 
morphology
Platelet count
White blood cell count (and 
morphology as applicable)
Total neutrophils (Abs)
Absolute neutrophils
Eosinophils (Abs)
Monocytes (Abs)
Basophils (Abs)
Lymphocytes (Abs)
Red blood cell indices (mean 
corpuscular volume, mean corpuscular 
hemoglobin, mean corpuscular 
hemoglobin concentration)
pH
Glucose (qual)
Protein (qual)
Blood (qual)
Ketones
Nitrites
Leukocyte esterase
Microscopy and culturea
Prothrombin time (PT)
activated partial 
thromboplastin time
C-reactive protein
Lipase
Amylase
Cystatin C
Haptoglobinb
Chemistry and Hepatic Safety
BUN and Creatinine
Glucose
Calcium
Sodium
Potassium
Chloride
Total CO2 (Bicarbonate)
AST, ALT
Total Bilirubin (direct and indirect bilirubin)
Alkaline phosphatase
Uric Acid
Albumin
Total protein
Serum Phosphorus
Gamma glutamyl transferase (GGT)
Glutamate dehydrogenase (GLDH)
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Table 3.
Protocol Required Safety Laboratory Assessments
For Screening (Visit 1) and Day 360 (Visit 19) Only
International normalized ratio (INR)
Hepatitis A virus (anti-HAV) immunoglobulin M
Hepatitis B surface antigen
Hepatitis C antibody
For Post IP Intensified Safety Monitoring (at Year 1 and Year 2)
Complement biomarkers eg, C3 and C4, additional exploratoryc
Haptoglobin- analyzed by local laboratory on Days 2 and 4 (Visits 4 and 5) in Year 1 and on Days 391 and 
393 (Visits 21 and 22) in Year 2 for sites in Japan.
Urine biomarkers
Other Assessments
Immunogenicity: NAb to AAV9; ELISpot to AAV9; ADA to AAV9; ELISpot to mini-dystrophin; 
ADA to mini-dystrophin
Viral vector shedding (whole blood, saliva, and urine)
Cardiac troponin I 
Creatine kinase
Conditional Testing
Genetic screening for aHUS-Central Laboratory, if needed as per Section 6.5.1
Local assessment of NT-ProBNP/BNP, if needed as per Section 8.2.7
LOCAL AND CENTRAL LABORATORY TESTING
Local Laboratory
Hematology: as per clinical safety panel, 
including blood smear for morphology. 
Absolute neutrophils are not required.
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Chemistry and hepatic safety: at a 
minimum, creatinine, BUN (or blood urea if 
BUN cannot be performed), calcium, 
sodium, potassium, chloride, total CO2 
(bicarbonate), uric acid and serum 
phosphorus; but excluding AST and ALT-
sensitive clinical data
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cystatin C (when possible)
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Urinalysis: as per clinical safety panel
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cardiac troponin I, (or cardiac troponin 
T if cardiac troponin I is not available)
Baseline Visit (Visit 2), Day 2 (Visit 4), Day 4 (Visit 5), 
Day 6 (Visit 6), Day 8 (Visit 8), and Day 10 (Visit 10) in 
Year 1
Day 390 (Visit 20), Day 391 (Visit 21), Day 393 (Visit 22), 
Day 395 (Visit 23), Day 397 (Visit 25), and Day 399 (Visit 
27) in Year 2
Serum creatinine
Baseline Visit, Day 2 and Day 4 (Visits 2, 4, and 5) in Year 
1
Day 390 to Day 393 (Visits 20 to 22) in Year 2
Local Laboratory for Japan Only
Local labs as described above 
Day 2 to Day 10 (Visit 4 to Visit 10) in Year 1
Day 391 to Day 399 (Visits 21 to 27) in Year 2
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Table 3.
Protocol Required Safety Laboratory Assessments
Haptoglobin (mandatory)
Other- prothrombin time,
activated partial thromboplastin time, 
CRP, amylase, lipase (when possible)
Day 2 and Day 4 (Visit 4 and Visit 5) in Year 1
Day 391 and Day 393 (Visits 21 and 22) in Year 2
Local Laboratory for Russia Only
Chemistry and hepatic safety
Baseline (Visit 2), Day 2 to Day 240 (Visit 4 to Visit 17) in 
Year 1d,e
Day 390 to Day 629 (Visit 20 to Visit 34) in Year 2d,e
Hematology
Screening Visit (Visit 1), Day 2 to Day 21 (Visit 4 to Visit 
12), Day 34 (Visit 13), Day 60 (Visit 14), Day 90 to Day 
240 (Visit 15 to Visit 17) and Day 360 (Visit 19) in Year 1f
Day 391 to Day 410 (Visit 21 to Visit 29), Day 423 (Visit 
30), Day 449 (Visit 31) and Day 479 to Day 629 (Visit 32 
to Visit 34) in Year 2
Cystatin C (when possible)
Day 2 to Day 240 (Visit 4 to Visit 17) in Year 1
Day 390 to Day 629 (Visit 20 to Visit 34) in Year 2
GLDH (when possible)
Day 2 to Day 240 (Visit 4 to Visit 17) in Year 1
Day 390 to Day 629 (Visit 20 to Visit 34) in Year 2
Urinalysis
Day 1 to Day 21 (Visit 3 to Visit 12) in Year 1
Day 390 to Day 410 (Visit 20 to Visit 29) in Year 2
Cardiac I, (or cardiac troponin T if 
cardiac troponin I is not available)
Baseline Visit (Visit 2), Day 2 (Visit 4), Day 4 (Visit 5), 
Day 6 (Visit 6), Day 8 (Visit 8), and Day 10 (Visit 10), Day 
21 to Day 120 (Visit 12 to Visit 16) in Year 1.
Day 390 to Day 509 (Visit 20 to Visit 33) in Year 2
Coagulation
Screening Visit (Visit 1), Day 2 to Day 21 (Visit 4 to Visit 
12), Day 34 (Visit 13), Day 60 (Visit 14), Day 90 to Day 
240 (Visit 15 to Visit 17) in Year 1
Day 391 to Day 410 (Visit 21 to Visit 29), Day 423 (Visit 
30), Day 449 (Visit 31) and Day 479 to Day 629 (Visit 32 
to Visit 34) in Year 2
Central Laboratory
Clinical safety (not for Japan)
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
Chemistry and hepatic safety (not for 
Japan)
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
Urinalysis (not for Japan)
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
GLDH
Day 9 (Visit 9) at Year 1
Day 398 (Visit 26) at Year 2
For sites in Japan additionally on Day 2 (Visit 4), Day 4 
(Visit 5) in Year 1, and on Day 391 (Visit 21) and Day 393 
(Visit 22) in Year 2
C3, C4
Days 6 to 10 (Visits 6 to 10) at Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cardiac troponin I
Day 7 (Visit 7) at Year 1
Day 396 (Visit 24) at Year 2
Day 42 (Visit 13.1) only for Germany)
Day 431 (Visit 30.1 only for Germany)
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Table 3.
Protocol Required Safety Laboratory Assessments
a.
Only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. Culture to be done 
locally.
b.
Only for the Screening Visit (Visit 1) and for Day 360 Visit (Visit 19).
c.
Additional biomarkers, such as ferritin, will be included so long as blood volume limits are not 
exceeded.
d.
Only creatinine is required at Baseline Visit (Visit 2) in Year 1 and on Day 390 (Visit 390) in Year 2.
e.
ALT and AST will not be analyzed locally, those samples will be sent to the central laboratory to 
prevent the results being shared with the site or the Sponsor (Section 6.3.).
f.
On Day 360 (Visit 19) the results of neutrophils and platelets are considered sensitive clinical data and 
are not shared with the site or the Sponsor. They will only be shared with the unblinded medical 
monitor so they can perform the determination of eligibility for Year 2 IP administration 
(Section 6.3.3). The local laboratories at the Russian sites will follow the same process.
Any remaining biospecimens samples collected for clinical safety may be retained and stored 
for the duration of the study. Retained samples may be used for the assessment of exploratory 
biomarkers. These data will not be included in the clinical study report. 
Investigators must document their review of each laboratory safety report.
Best Practice for Pediatric Blood Collection
Examples of best practices for pediatric blood collection which should be included in lab 
manuals and training materials include:
Ensure that the child is well-hydrated prior to blood collection.
Keep the child warm throughout the process of preparing for and drawing blood.
Engage caregivers to determine what is the most appropriate way to soothe their child.

A lidocaine-based topical anesthetic (eg, lidocaine 4% cream) may be used prior to 
blood collection to decrease potential discomfort to the subject. The anesthetic must 
not contain propylene glycol (PG). The skin must be thoroughly cleansed prior to 
blood sample collection. It is recommended that two venipuncture sites be prepared 
with local anesthetic in case the first attempt is not successful.

Adhere strictly to a limit on the number of venipuncture attempts in a pediatric 
participant. If no satisfactory sample has been collected after 2 attempts, seek a 
second opinion to decide whether to make a further attempt or cancel the tests.
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10.3. Appendix 3: Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting
10.3.1. Definition of AE
AE Definition

An AE is any untoward medical occurrence in a patient or clinical study participant, 
temporally associated with the use of study intervention, whether or not considered 
related to the study intervention.

NOTE: An AE can therefore be any unfavorable and unintended sign (including an 
abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally 
associated with the use of study intervention.
Events Meeting the AE Definition

Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) 
or other safety assessments (eg, ECG, radiological scans, vital sign measurements), 
including those that worsen from baseline, considered clinically significant in the 
medical and scientific judgment of the Investigator (ie, not related to progression of 
underlying disease).

Exacerbation of a chronic or intermittent preexisting condition including either an 
increase in frequency and/or intensity of the condition.

New conditions detected or diagnosed after study intervention administration even 
though it may have been present before the start of the study.

Signs, symptoms, or the clinical sequelae of a suspected drug-drug interaction.

Signs, symptoms, or the clinical sequelae of a suspected overdose of either study 
intervention or a concomitant medication. Overdose per se will not be reported as an 
AE/SAE unless it is an intentional overdose taken with possible 
suicidal/self-harming intent. Such overdoses should be reported regardless of 
sequelae.

“Lack of efficacy” or “failure of expected pharmacological action” per se will not be 
reported as an AE or SAE. Such instances will be captured in the efficacy 
assessments. However, the signs, symptoms, and/or clinical sequelae resulting from 
lack of efficacy will be reported as an AE or SAE if they fulfill the definition of an 
AE or SAE.
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Events NOT Meeting the AE Definition

Any clinically significant abnormal laboratory findings or other abnormal safety 
assessments which are associated with the underlying disease, unless judged by the 
Investigator to be more severe than expected for the participant’s condition.

The disease/disorder being studied or expected progression, signs, or symptoms of 
the disease/disorder being studied, unless more severe than expected for the 
participant’s condition.

Medical or surgical procedure (eg, endoscopy, appendectomy): the condition that 
leads to the procedure is the AE.

Situations in which an untoward medical occurrence did not occur (social and/or 
convenience admission to a hospital).

Anticipated day-to-day fluctuations of preexisting disease(s) or condition(s) present 
or detected at the start of the study that do not worsen.
10.3.2. Definition of SAE
If an event is not an AE per definition above, then it cannot be an SAE even if serious 
conditions are met (eg, hospitalization for signs/symptoms of the disease under study, death 
due to progression of disease).
An SAE is defined as any untoward medical occurrence that, at any dose:
a.
Results in death
b. Is life-threatening
The term “life-threatening” in the definition of “serious” refers to an event in which the 
participant was at risk of death at the time of the event. It does not refer to an event that 
hypothetically might have caused death if it were more severe.
c.
Requires inpatient hospitalization or prolongation of existing hospitalization
In general, hospitalization signifies that the participant has been detained (usually 
involving at least an overnight stay) at the hospital or emergency ward for observation 
and/or treatment that would not have been appropriate in the physician’s office or 
outpatient setting. Complications that occur during hospitalization are AEs. If a 
complication prolongs hospitalization or fulfills any other serious criteria, the event is 
serious. When in doubt as to whether “hospitalization” occurred or was necessary, the 
AE should be considered serious.
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An SAE is defined as any untoward medical occurrence that, at any dose:
Hospitalization for elective treatment of a preexisting condition that did not worsen from 
baseline is not considered an AE.
d. Results in persistent disability/incapacity

The term disability means a substantial disruption of a person’s ability to 
conduct normal life functions.

This definition is not intended to include experiences of relatively minor 
medical significance such as uncomplicated headache, nausea, vomiting, 
diarrhea, influenza, and accidental trauma (eg, sprained ankle) which may 
interfere with or prevent everyday life functions but do not constitute a 
substantial disruption.
e.
Is a congenital anomaly/birth defect
f.
Other situations:

Medical or scientific judgment should be exercised in deciding whether SAE 
reporting is appropriate in other situations such as important medical events that 
may not be immediately life-threatening or result in death or hospitalization but 
may jeopardize the participant or may require medical or surgical intervention to 
prevent one of the other outcomes listed in the above definition. These events 
should usually be considered serious.

Examples of such events include invasive or malignant cancers, intensive 
treatment in an emergency room or at home for allergic bronchospasm, blood 
dyscrasias or convulsions that do not result in hospitalization, or development of 
drug dependency or drug abuse.

Suspected transmission via a Pfizer product of an infectious agent, pathogenic or 
non-pathogenic, is considered serious. The event may be suspected from clinical 
symptoms or laboratory findings indicating an infection in a patient exposed to a 
Pfizer product. The terms “suspected transmission” and “transmission” are 
considered synonymous. These cases are considered unexpected and handled as 
serious expedited cases by pharmacovigilance personnel. Such cases are also 
considered for reporting as product defects, if appropriate.
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10.3.3. Recording/Reporting and Follow-up of AEs and/or SAEs
AE and SAE Recording/Reporting
The table below summarizes the requirements for recording adverse events on the CRF 
and for reporting serious adverse events on the Clinical Trial (CT) Serious Adverse 
Event (SAE) Report Form to Pfizer Safety. These requirements are delineated for 3 types 
of events: (1) SAEs; (2) nonserious adverse events (AEs); and (3) exposure to the 
investigational product under study during pregnancy or breastfeeding, and occupational 
exposure. 
It should be noted that the CT SAE Report Form for reporting of SAE information is not 
the same as the AE page of the CRF. When the same data are collected, the forms must 
be completed in a consistent manner. AEs should be recorded using concise medical 
terminology and the same AE term should be used on both the CRF and the CT SAE 
Report Form for reporting of SAE information.
Safety Event
Recorded on the CRF
Reported on the CT SAE 
Report Form to Pfizer 
Safety Within 24 Hours 
of Awareness
SAE
All
All
Nonserious AE
All
None
Exposure to the 
investigational product 
under study during 
pregnancy or 
breastfeeding, and 
occupational exposure
All AEs/SAEs associated 
with exposure during 
pregnancy or breastfeeding
Occupational exposure is 
not recorded
All (and exposure during 
pregnancy [EDP] 
supplemental form for 
EDP) 
Note: Include all SAEs 
associated with exposure 
during pregnancy or 
breastfeeding. Include all 
AEs/SAEs associated with 
occupational exposure.

When an AE/SAE occurs, it is the responsibility of the Investigator to review all 
documentation (eg, hospital progress notes, laboratory reports, and diagnostic 
reports) related to the event.

The Investigator will then record all relevant AE/SAE information in the CRF.

It is not acceptable for the Investigator to send photocopies of the participant’s 
medical records to Pfizer Safety in lieu of completion of the CT SAE Report 
Form/AE/SAE CRF page.
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
There may be instances when copies of medical records for certain cases are 
requested by Pfizer Safety. In this case, all participant identifiers, with the 
exception of the participant number, will be redacted on the copies of the medical 
records before submission to Pfizer Safety.

The Investigator will attempt to establish a diagnosis of the event based on signs, 
symptoms, and/or other clinical information. Whenever possible, the diagnosis 
(not the individual signs/symptoms) will be documented as the AE/SAE.
Assessment of Intensity
The Investigator will make an assessment of intensity for each AE and SAE reported 
during the study and assign it to 1 of the following categories: 

Mild: An event that is easily tolerated by the participant, causing minimal 
discomfort and not interfering with everyday activities.

Moderate: An event that causes sufficient discomfort and interferes with normal 
everyday activities.

Severe: An event that prevents normal everyday activities. An AE that is 
assessed as severe should not be confused with an SAE. Severe is a category 
utilized for rating the intensity of an event; and both AEs and SAEs can be 
assessed as severe.

An event is defined as “serious” when it meets at least 1 of the predefined 
outcomes as described in the definition of an SAE, NOT when it is rated as 
severe.
Assessment of Causality

The Investigator is obligated to assess the relationship between study intervention 
and each occurrence of each AE/SAE.

A “reasonable possibility” of a relationship conveys that there are facts, 
evidence, and/or arguments to suggest a causal relationship, rather than a 
relationship cannot be ruled out.

The Investigator will use clinical judgment to determine the relationship.

Alternative causes, such as underlying disease(s), concomitant therapy, and other 
risk factors, as well as the temporal relationship of the event to study intervention 
administration will be considered and investigated.
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Assessment of Causality

The Investigator will also consult the Investigator’s brochure (IB) and/or product 
information, for marketed products, in their assessment.

For each AE/SAE, the Investigator must document in the medical notes that 
he/she has reviewed the AE/SAE and has provided an assessment of causality.

There may be situations in which an SAE has occurred and the Investigator has 
minimal information to include in the initial report to the Sponsor. However, it is 
very important that the Investigator always make an assessment of causality 
for every event before the initial transmission of the SAE data to the 
Sponsor.

The Investigator may change their opinion of causality in light of follow-up 
information and send an SAE follow-up report with the updated causality 
assessment.

The causality assessment is one of the criteria used when determining regulatory 
reporting requirements.

If the Investigator does not know whether or not the investigational product 
caused the event, then the event will be handled as “related to investigational 
product” for reporting purposes, as defined by the Sponsor. In addition, if the 
Investigator determines that an SAE is associated with study procedures, the 
Investigator must record this causal relationship in the source documents and 
CRF, and report such an assessment in the dedicated section of the CT SAE 
Report Form and in accordance with the SAE reporting requirements.
Follow-up of AEs and SAEs

The Investigator is obligated to perform or arrange for the conduct of 
supplemental measurements and/or evaluations as medically indicated or as 
requested by the Sponsor to elucidate the nature and/or causality of the AE or 
SAE as fully as possible. This may include additional laboratory tests or 
investigations, histopathological examinations, or consultation with other 
healthcare professionals.

If a participant dies during participation in the study or during a recognized 
follow-up period, the Investigator will provide Pfizer Safety with a copy of any 
postmortem findings including histopathology.

New or updated information will be recorded in the originally completed CRF.
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Follow-up of AEs and SAEs

The Investigator will submit any updated SAE data to the Sponsor within 24 
hours of receipt of the information.
10.3.4. Reporting of SAEs
SAE Reporting to Pfizer Safety via an Electronic Data Collection Tool

The primary mechanism for reporting an SAE to Pfizer Safety will be the 
electronic data collection tool.

If the electronic system is unavailable, then the site will use the paper SAE data 
collection tool (see next section) in order to report the event within 24 hours.

The site will enter the SAE data into the electronic system as soon as the data 
become available.

After the study is completed at a given site, the electronic data collection tool 
will be taken off-line to prevent the entry of new data or changes to existing data.

If a site receives a report of a new SAE from a study participant or receives 
updated data on a previously reported SAE after the electronic data collection 
tool has been taken off-line, then the site can report this information on a paper 
SAE form (see next section) or to Pfizer Safety by telephone.
SAE Reporting to Pfizer Safety via CT SAE Report Form

Facsimile transmission of the CT SAE Report Form is the preferred method to 
transmit this information to Pfizer Safety.

In circumstances when the facsimile is not working, notification by telephone is 
acceptable with a copy of the CT SAE Report Form sent by overnight mail or 
courier service.

Initial notification via telephone does not replace the need for the Investigator to 
complete and sign the CT SAE Report Form pages within the designated 
reporting time frames.
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10.4. Appendix 4: Contraceptive and Barrier Guidance 
10.4.1. Male Participant Reproductive Inclusion Criteria
The potential risk of exposure to fordadistrogene movaparvovec in a sexual partner of a male 
participant in this study via ejaculate is low, and therefore no contraception (condom) use in 
male participants is warranted. 
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PFIZER CONFIDENTIAL
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10.5. Appendix 5: Genetics
Use/Analysis of DNA

Genetic variation may impact a participant’s response to study intervention, 
susceptibility to, and severity and progression of disease. Therefore, where local 
regulations and IRBs/ECs allow, a blood sample will be collected for DNA analysis.

Genetic research may consist of the analysis of 1 or more candidate genes or the 
analysis of genetic markers throughout the genome or analysis of the entire genome 
(as appropriate).

The samples may be analyzed as part of a multistudy assessment of genetic factors 
involved in the response to study intervention or study interventions of this class to 
understand treatments for the disease(s) under study or the disease(s) themselves.

The results of genetic analyses may be reported in the clinical study report (CSR) or 
in a separate study summary,  or may be used for internal decision making without 
being included in a study report.

The Sponsor will store the DNA samples in a secure storage space with adequate 
measures to protect confidentiality. 

The samples will be retained as indicated:

Samples for specified genetic analysis (see Section 8.7.1) will not be stored 
beyond the completion of this study (eg, CSR finalization).

Samples for banking (see Section 8.7.2 and Section 8.8.4) will be stored 
indefinitely or other period as per local requirements. 

Participants may withdraw their consent for the storage and/or use of their banked 
biospecimens at any time by making a request to the Investigator; in this case, any 
remaining material will be destroyed. Data already generated from the samples will 
be retained to protect the integrity of existing analyses. 

Banked biospecimens will be labeled with a code. The key between the code and the 
participant’s personally identifying information (eg, name, address) will be held at the 
study site and will not be provided to the sample bank.
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10.6. Appendix 6: Liver Safety: Suggested Actions and Follow-up Assessments 
Potential Cases of Drug Induced Liver Injury
Humans exposed to a drug who show no sign of liver injury (as determined by elevations in 
transaminases) are termed “tolerators,” while those who show transient liver injury, but adapt 
are termed “adaptors.” In some participants, transaminase elevations are a harbinger of a 
more serious potential outcome. These participants fail to adapt and therefore are 
"susceptible" to progressive and serious liver injury, commonly referred to as drug-induced 
liver injury (DILI). Participants who experience a transaminase elevation above 3 times the 
upper limit of normal (× ULN) should be monitored more frequently to determine if they are 
an “adaptor” or are “susceptible.”
In the majority of DILI cases, elevations in aspartate aminotransferase (AST) and/or alanine 
aminotransferase (ALT) precede total bilirubin (TBili) elevations (>2 × ULN) by several 
days or weeks. The increase in TBili typically occurs while AST/ALT is/are still elevated 
above 3 × ULN (ie, AST/ALT and TBili values will be elevated within the same laboratory 
sample). In rare instances, by the time TBili elevations are detected, AST/ALT values might 
have decreased. This occurrence is still regarded as a potential DILI. Therefore, abnormal 
elevations in either AST OR ALT in addition to TBili that meet the criteria outlined below 
are considered potential DILI (assessed per Hy’s law criteria) cases and should always be 
considered important medical events, even before all other possible causes of liver injury 
have been excluded.
The threshold of laboratory abnormalities for a potential DILI case depends on the 
participant’s individual baseline values and underlying conditions. Participants who present 
with the following laboratory abnormalities should be evaluated further as potential DILI 
(Hy’s law) cases to definitively determine the etiology of the abnormal laboratory values:

Participants with AST/ALT and TBili baseline values within the normal range who 
subsequently present with AST OR ALT values >3 × ULN AND a TBili value 
>2 × ULN with no evidence of hemolysis and an alkaline phosphatase value 
<2 × ULN or not available.

For participants with baseline AST OR ALT OR TBili values above the ULN, the 
following threshold values are used in the definition mentioned above, as needed, 
depending on which values are above the ULN at baseline:
Preexisting AST or ALT baseline values above the normal range: AST or ALT values 
>2 times the baseline values AND >3 × ULN; or >8 × ULN (whichever is 
smaller).
Preexisting values of TBili above the normal range: TBili level increased from 
baseline value by an amount of at least 1 × ULN or if the value reaches 
>3 × ULN (whichever is smaller).
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Rises in AST/ALT and TBili separated by more than a few weeks should be assessed 
individually based on clinical judgment; any case where uncertainty remains as to whether it 
represents a potential Hy’s law case should be reviewed with the Sponsor. 
It is important to note that standard biomarkers for the onset of hepatocellular injury such as 
ALT and AST are difficult to interpret in patients with DMD, as they are also released from 
the diseased skeletal muscle. The criteria listed above for Hy’s law in the setting of 
participants with baseline AST or ALT values above the ULN will be used, when applicable. 
GLDH, which is a liver-specific enzyme not elevated in patients with DMD, will be collected 
to aid in the evaluation of potential hepatocellular injury. Elevations of GLDH >2 x ULN 
will also be assessed individually, and participants who experience a consistent GLDH 
elevation above 3 × ULN may be monitored more frequently, based on the clinical judgment 
of the Investigator and with the assistance of the ad hoc hepatic and/or 
immunopharmacologic expert(s) supporting the E-DMC. Any case where uncertainty 
remains as to whether it represents a potential Hy’s law case should be reviewed with the 
Sponsor. 
The participant should return to the Investigator site and be evaluated as soon as possible, 
preferably within 48 hours from awareness of the abnormal results. This evaluation should 
include laboratory tests, detailed history, and physical assessment. 
In addition to repeating measurements of AST and ALT and TBili for suspected cases of 
Hy’s law, additional laboratory tests should include albumin, creatine kinase (CK), direct and 
indirect bilirubin, gamma-glutamyl transferase (GGT), prothrombin time (PT)/international 
normalized ratio (INR), total bile acids, and alkaline phosphatase. Consideration should also 
be given to drawing a separate tube of clotted blood and an anticoagulated tube of blood for 
further testing, as needed, for further contemporaneous analyses at the time of the recognized 
initial abnormalities to determine etiology. A detailed history, including relevant information, 
such as review of ethanol, acetaminophen (either by itself or as a coformulated product in 
prescription or over-the-counter medications), recreational drug, supplement (herbal) use and 
consumption, family history, sexual history, travel history, history of contact with a 
jaundiced person, surgery, blood transfusion, history of liver or allergic disease, and potential 
occupational exposure to chemicals, should be collected. Further testing for acute hepatitis A, 
B, C, D, and E infection and liver imaging (eg, biliary tract) and collection of serum sample 
for acetaminophen drug and/or protein adduct levels may be warranted. 
All cases demonstrated on repeat testing as meeting the laboratory criteria of AST/ALT and 
TBili elevation defined above should be considered potential DILI (Hy’s law) cases if no 
other reason for the liver function test (LFT) abnormalities has yet been found. Such 
potential DILI (Hy’s law) cases are to be reported as SAEs, irrespective of availability 
of all the results of the investigations performed to determine etiology of the LFT 
abnormalities.
A potential DILI (Hy’s law) case becomes a confirmed case only after all results of 
reasonable investigations have been received and have excluded an alternative etiology.
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PFIZER CONFIDENTIAL
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10.7. Appendix 7: ECG Findings of Potential Clinical Concern
ECG Findings That May Qualify as Adverse Events (AEs)

New prolongation of corrected QT (Fridericia method) (QTcF) to >480 msec 
(absolute) or by ≥60 msec from baseline.
ECG Findings That May Qualify as Serious Adverse Events (SAEs)

QTcF prolongation >500 msec.
ECG Findings That Qualify as Serious Adverse Events

Change in pattern suggestive of new myocardial infarction. 

Sustained ventricular tachyarrhythmias (>30 seconds’ duration).

Second- or third-degree AV block requiring pacemaker placement.

Asystolic pauses requiring pacemaker placement.

Atrial flutter or fibrillation with rapid ventricular response requiring 
cardioversion.

Ventricular fibrillation/flutter.

At the discretion of the Investigator, any arrhythmia classified as an adverse 
experience.
The enumerated list of major events of potential clinical concern are recommended as “alerts” or 
notifications from the core ECG laboratory to the Investigator and Pfizer study team, and not to be 
considered as all inclusive of what to be reported as AEs/SAEs.
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10.8. Appendix 8: Country-Specific Requirements
10.8.1. France Contrat Unique
1. GCP Training 
a.
Before enrolling any participants, the Investigator and any subinvestigators will 
complete the Pfizer-provided Good Clinical Practice training course (“Pfizer GCP 
Training”) or training deemed equivalent by Pfizer. Any Investigators who later 
join the study will do the same before performing study-related duties. For studies 
of applicable duration, the Investigator and subinvestigators will complete Pfizer 
GCP Training or equivalent every 3 years during the term of the study, or more 
often if there are significant changes to the ICH GCP guidelines or course 
materials. 
2. Investigational Product. 
b. No participants or third-party payers will be charged for investigational product.
3. Urgent Safety Measures.
c.
In addition, the Investigator will inform Pfizer immediately of any urgent safety 
measures taken by the Investigator to protect the study participants against any 
immediate hazard, and of any serious breaches of this protocol or of ICH GCP 
that the Investigator becomes aware of.
4. Termination Rights. 
a.
Pfizer retains the right to discontinue development of fordadistrogene 
movaparvovec at any time.
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10.9. Appendix 9. Italy-Specific Country Amendment
This appendix is only for investigators in Italy.
10.9.1. Schedule of Activities 
10.9.1.1. Schedule of Activities - Year 1 (Screening to Year 1 Day 360) 
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Informed 
consent/assent
X
Demography
X
Medical history
Xhh
Medication 
history
X
Review of 
inclusion/exclusi
on criteria
X
X
Eligibility for 
Year 1 IP 
administrationv
X
Hospital stayii
X




X
Physical 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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Page 162
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Neurological 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
Weight
X
X
X
X
X
X
X
Height
X
X
X
X
X
X
Vital signs 
(supine BP, 
respiratory rate, 
PR, body temp, 
and O2 
saturation)i,j
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGk
X
X
X
X
X
X
CBCL
X
X
X
g
Randomization
Xbb
Laboratory Assessmentsl
Blood Samples
NAb
X
Xcc
X
X
X
g
ADA to 
mini-dystroph
in and AAV9
X
Xee
Xee
Xee
X
X
X
X
g
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Page 163
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
ELISpot to
mini-
dystrophin 
and AAV9
X
X
X
g
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
g
Clinical safety 
(hematology, 
other)l
X
X
X
X
X
X
X
X
X
X
X
X
g
Chemistry and 
hepatic safetyl
X
X
X
X
X
Xdd
X
X
X
X
X
X
X
X
X
Post IP 
intensified safety 
monitoringl,w
X
X
X
X
X
Local and central 
laboratory 
testingaa
X
X
X
X
X
X
X
Cardiac 
Troponin I
X
X
X
X
X
X
X
X
X
X
X
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PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 164
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
International 
normalized ratio 
(INR),
Hepatitis A virus 
(anti-HAV) 
immunoglobulin
M 
Hepatitis B 
surface antigen,
Hepatitis C 
antibodyl
X
X
Biomarker 
(creatine kinase)l
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked 
biospecimens for 
biomarkersm
X
X
X
Banked 
biospecimens for 
geneticsn
X
Urine Samples
Clinical safety 
(urinalysis)l
X
X
X
X
X
X
X
X
X
X
g
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PFIZER CONFIDENTIAL
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Page 165
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Banked 
biospecimens for 
biomarkersm
X
X
X
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Saliva Samples
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Tissue Samples
Muscle biopsyo
X
Xx
Imaging 
Assessments
Echocardiogramp
X
X
X
g
Cardiac MRIff
Xgg
Xgg
Functional Assessments
FVCq,y
X
X
X
g
NSAAq
X
X
X
X
X
X
X
Ankle range of 
motion 
X
X
X
X
X
X
X
Ambulatory 
status
Xr
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 166
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Actigraphys
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI 
- Pediatric 
Parentt
X
X
X
X
EQ-5D-Y Proxyt
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGt
X
X
X
X
X
X
Participant-completed
EQ-5D-Yt
X
X
Clinical evaluator-
completed
CGISq
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
WPAI:DMD 
Caregiver
X
Interventions
Protocol-
mandated 
glucocorticoid 
regimenu
X
X












X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 167
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Background 
glucocorticoid 
regimen
X
X
X




IP administration
X
Meningococcal 
vaccine
X
X
Ongoing 
monitoring
Concomitant 
medications
X




















X
Serious and 
nonserious 
adverse event 
monitoring 
X




















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9=adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG=electrocardiogram; ELISpot=Enzyme-Linked ImmunoSpot; EQ-5D-Y=EuroQol 5 
Dimensions–Youth; FVC=Forced Vital Capacity; IP=investigational product; Men ACWY=Meningococcal serogroups A, C, W, and Y; NAb=neutralizing antibodies; 
NSAA=North Star Ambulatory Assessment; PGIS=patient global impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; temp=temperature; PR=pulse 
rate.
a.
Visit 1 – Screening Visit 

During screening, participants and caregiver(s) will be assessed for study eligibility in accordance with the Inclusion/Exclusion Criteria as described in Section 5.1 and 
Section 5.2; 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 168
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Visit 1 must be conducted over the course of 2 days. The investigator will decide which of the schedules below they will follow and inform the study team:

Schedule A:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. Second day: should take place immediately after or as soon as 
possible, after the first day: clinical safety (See Appendix 2), INR, cardiac troponin I.

Schedule B:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers and viral vector shedding. Second day: must take place only when the results of the test for 
NAb to AAV9 are available. The time between the first and second day of the Screening Visit is expected to be between 3-4 weeks (based on the time to 
obtain the results of the NAb to AAV9 test). Only participants with a negative test for NAb to AAV9 will perform the rest of the Visit 1 assessments as per 
SoA. This includes the collection of blood and urine for: clinical safety tests (see Appendix 2), INR and cardiac troponin I. Participants with a positive test for 
NAb to AAV9 will be screen failed and will not attend the second day of Screening Visit (Visit 1).

Informed consent must be provided by the caregiver(s). The participant may also be required to provide assent in compliance with local regulations and institutional 
review board (IRB) requirements;

Screening blood tests with results considered by the Investigator to be transient and inconsistent with the participant’s clinical condition may be repeated once 
during the screening period for confirmation of eligibility;

Demographics: Information such as date of birth, race and ethnicity and gender will be collected in compliance with local regulations;

Medical history will include results of genetic testing for confirmation of diagnosis of DMD. Results must confirm the presence of an abnormality (eg, deletion, 
duplication), or a point mutation in the dystrophin gene(s) which is consistent with the diagnosis of DMD. The mutation type will be reported. If the Investigator 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 169
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
determines that the results are inconclusive, a repeat genetic testing will be allowed through the central laboratory at Screening (Visit 1) prior to any other 
assessments. In that case participants may return for the remainder of Screening (Visit 1) once results are confirmed (Section 8.7.1);

Medical history will also be reviewed for any significant medical history and concurrent illness(es) that required or are requiring specialist consultation or treatment;

Medication history: Complete medication history will include all prescription or nonprescription drugs, and dietary and herbal supplements taken within 30 days prior to 
the Screening Visit (Visit 1). The date the participant first started glucocorticoids for their DMD and the date of start of the background glucocorticoid regimen that the 
participant is taking at the time of Visit 1 (Screening Visit) must also be documented. In addition, the general immunization status including the immunization status 
against meningococcus, and any other vaccine(s) required by the eculizumab local prescribing information, must be documented;

Meningococcal vaccine: Participants who have no contraindications and who have not previously received a MenACWY vaccination; or whose last vaccination at the 
time of the Screening Visit (Visit 1) is outside the time period of active coverage specified by the vaccine manufacturer (Visit 1) must receive at least one dose of 
MenACWY vaccine as early as possible in the Screening Period and not later than 30 days before IP administration (see Section 6.5.1). Participants must also receive 
MenB vaccination if indicated by national vaccination guidelines. In addition, local eculizumab prescribing information, including additional vaccination and other 
requirements must also be followed (see Section 6.5.1).

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
b.
Visit 14 and Visit 19 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern 
and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood 
collection, may be performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory samples must be collected: 
Visit 14 (Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
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Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 170
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
Visit 19 (Week 52)
First day: anti-HAV immunoglobulin M, Hepatitis B surface antigen, Hepatitis C antibody (these tests will not be applicable for Cohort 1 participants confirmed to 
meet exclusion criterion 15 [see Section 5.2]), NAb to AAV9, ADA to mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding.
Second day: clinical safety, INR, cardiac troponin I, biomarker (creatine kinase). 
c.
Visit 2 – Baseline Visit

Meningococcal vaccine: Only applicable for participants who have not received this vaccination at Screening (please refer to footnote a).

For sites outside the US, the Baseline visit must occur at least 45 calendar days prior to the planned IP administration visit, Day 1 (Visit 3), to allow for timely delivery 
of IP to the site, unless notified of earlier IP delivery by the study team. For US sites the Baseline visit should occur at least 16 calendar days prior to the planned IP 
administration visit, Day 1 (Visit 3), to allow for timely delivery of IP to the site, unless notified of earlier or later IP delivery by the study team; 

IP will be shipped to site following confirmation of participant’s eligibility (Section 5.1 and Section 5.2) and randomization. The amount of IP to be shipped to the site 
for IP administration at Visit 3 will be based on the measurement of body weight at the Baseline Visit (Visit 2). Body weight measurement must be verified by two site 
personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site.

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
d.
Visit 3 – Week 1, Day 1 (Day of IP administration)

Prior to IP administration, the Investigator must confirm applicable IP eligibility criteria (Section 6.1.1);

Participants will be instructed not to take their background glucocorticoid dose on Day 1 (Visit 3);
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Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 171
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13

Participants are to be admitted to the site;

The following assessments must be performed prior to IP administration: physical examination, urine sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone 1 to 4 hours prior to infusion of IP; 

IP administration over approximately 2 to 4 hours (-15 minutes to +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site to enable prompt follow-up in the event of any emergent AEs through Day 14 (Visit 11), or longer if deemed necessary.
e.
Visits 12, 12.2, 13.2, 14.2 and 15

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
f.
Visit 18

This visit may be performed remotely (at or close to the participant’s home); in that case, it should include phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.

Amount of IP to be shipped to site for the IP administration on Day 390 (Visit 20) will be based on the measurement of body weight obtained at this visit. Body weight 
measurement must be verified by two site personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site. 
This visit is not applicable for Cohort 1 participants confirmed to meet exclusion criterion 15 (see Section 5.2).
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Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13

For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be shipped to the site will be determined once the study has been 
restarted. Therefore, the weight collected at Day 328 (Visit 18) will not be entered into the interactive response technology drug management system during the dosing 
pause. Participants will be evaluated for Year 2 IP eligibility when the study is restarted.

May not be applicable for participants confirmed to meet exclusion criterion 15 or those who declined Year 2 IP administration (see Appendix 12 and Section 7.2.1).
g.
Early Discontinuation Visit

This visit is not applicable for participants who withdraw prior to Day 1 (Visit 3) or for Cohort 2 participants who are withdrawn from the study between Day 360 (Visit 
19) and Day 390 (Visit 20) (see Section 7.1).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only if the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
h.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable post-baseline unless safety concerns warrant full examination.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
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Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
i.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
j.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
k.
12-Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
l.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 

For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 

On the following visits: Baseline Visit (Visit 2), Day 60 (Visit 14), Day 120 (Visit 16), Day 240 (Visit 17) and Day 360 (Visit 19), in which functional assessments (eg, 
NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for additional 
advice regarding the ordering of assessments please consult the Functional Assessment Manual.
m.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
n.
Banked biospecimens for genetics are collected as described in Section 8.7.2.
o.
Open muscle biopsies will be obtained in approximately the first 15 participants randomized into Cohorts 1 and 2, and their siblings, at sites that have been trained and 
certified by the Sponsor/Sponsor designee to collect open muscle biopsies, following administration of an anesthetic (eg, regional block or under general anesthesia) 
according to institutional standard practice, and only after any imaging and functional assessments scheduled for the same visit have been completed. Baseline visit muscle 
biopsies will be performed after randomization. If a muscle biopsy cannot be scheduled on the day of the Baseline Visit, the biopsy may be performed at a later day, as long 
as it is at least 2 weeks before dosing.
p.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
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Page 174
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
q.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, ankle range of motion and FVC may be video recorded at the Day 1 
(Screening Visit), Baseline Visit (Visit 2), and at the annual visits (ie, Visits 19, 35, 37, 39, 41, 43). If CE re-training is required, the assigned master physiotherapist may 
request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be performed early in the course of the visit, to help reduce 
the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
r.
Ambulatory assessment at Screening (Visit 1) is based only on the ability to perform the 10 m run/walk, as assessed during the NSAA.
s.
An activity monitor will be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
t.
COAs will be completed by the caregiver on behalf of the participant and/or by the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
u.
Starting on Day 1 (Visit 3) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1).
v.
For eligibility for Year 1 IP administration please see Section 6.1.1.
w.
For details regarding post IP intensified safety monitoring please see Section 8.2.10. 
x.
All participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo 2 post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-baseline muscle biopsy cannot be performed on 
the scheduled day, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing for the biopsy at Visit 19 and within 1 month of the day of the 
visit for the biopsy at Visit 41.
y.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
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Page 175
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
z.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) only after IP administration, as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a 
particular matrix (sample type) will be stopped when at least 2 consecutive negative results are observed in that matrix.
aa.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 9 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data.  C3/C4 will also be sent to the central laboratory at Visits 6, 7, 8, 9, and 10. For more 
details please see Section 8.2.11 and Appendix 2. 
bb. In order to ensure an adequate understanding and management of potential safety risks, the initial rate of randomization into the study will be limited. No more than 2 
participants per week will be randomized at the start of the study, until 4 participants have been observed for at least 2 weeks post-IP administration. After that, the rate could 
be increased to no more than 3 participants randomized per week (until at total of 10 participants have been observed for at least 2 weeks post-IP administration). Thereafter, 
the rate of randomization could be further increased to no more than 5 participants randomized per week (until a total of 20 participants have been observed for at least 2 
weeks post-IP administration). After this time, no limits of the randomization rate will be imposed unless the study team, in consultation with the E-DMC, determines 
otherwise. For more details please see Section 4.1.
cc.
The NAb to AAV9 blood samples at the Baseline Visit (Visit 2) will always be collected and sent to the Central Laboratory, but will only be analyzed and reviewed prior to 
Day 1 Visit (Visit 3) if the time between the first blood draw for NAb to AAV9 testing at the Screening Visit (Visit 1) or most recent test, if repeat blood draw(s) was required, 
and the Day 1 Visit (Visit 3) is expected to be more than 55 days, which is anticipated to occur rarely. Dosing cannot occur unless there is a negative test to AAV9 from a 
sample collected 55 or less days before the day of IP administration.
dd. On Day 28 (Visit 12.2), only GLDH will be collected.
ee.
ADA to mini-dystrophin only.
ff.
The Investigator will discuss with the participant and caregiver the importance of having a baseline cardiac MRI, even under general anesthesia, to be able to assess and 
manage potential cardiac events during the study. This discussion and the decision to perform or not a baseline cardiac MRI will be documented in the participant's records. 
A Participant requiring anesthesia or unable to undergo investigation with closed MRI (eg, metal implants) may be exempt, and will be allowed to be randomized in the 
study without a cardiac MRI. Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 176
Period
Screenin
g
Baselin
e
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a,b
Visit 2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.2e
Visit 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screenin
g
Baselin
e
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Wee
k 5
Wee
k 7
Wee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Week 
52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
7
7
14
7
Approximate 
Blood Volume 
(ml)
15
13.5
0
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
8
8
7
0
13
(Section 2.3.3.7). If the site considers gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast 
administration will be performed. It is important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may 
be required in certain situations (Section 8.2.8).
gg. Cardiac MRI may be performed at any time between the first day of the Screening Visit (Visit 1) and the Day 1 Visit (Visit 3), and after randomization, as long as it is done 
before Day 1 (Visit 3). If a prior cardiac MRI was performed within 6 months of the Screening Visit (with gadolinium, or without gadolinium if contrast administration is 
contraindicated), and results are available, then a cardiac MRI at screening will not be performed. Only participants with a pre-IP administration cardiac MRI will have a 
follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
hh. Participants will be assessed by a cardiologist at the Screening Visit, see Section 5.2, exclusion criteria 16 and 17.
ii.
Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
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Page 177
10.9.1.2. Schedule of Activities - Year 2 and Long-Term Follow Up 
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
Eligibility for Year 2 IP 
administrationr
X
Hospital staydd
X




X
Physical examinationg
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationg
X
X
X
X
X
X
X
X
X
X
X
X
Height and Weight
X
X
X
X
X
X
X
Vital signs (supine BP, 
respiration, PR, body 
temp, and O2 
saturation)h,i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGj
X
X
X
X
X
X
CBCL
X
X
X
Xe
Laboratory Assessmentsk
Blood Samples
 NAb to AAV9
X
X
X
Xe
  ADA to mini-dystrophin 
and AAV9
Xz
Xz
Xz
X
X
X
X
Xe
  ELISpot to mini-
dystrophin and AAV9
X
X
Xw
Xe
Viral Vector Sheddingu
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
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Page 178
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
Clinical safety 
(hematology, other)k
X
X
X
X
X
X
X
X
X
X
X
X
Xe
Chemistry and hepatic 
safetyk
X
X
Xy
X
X
X
X
X
X
X
X
X
X
X
Post IP intensified safety 
monitoringk,s
X
X
X
X
X
Local and central 
laboratory testingx
X
X
X
X
X
X
X
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
Biomarker (creatine 
kinase)k
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked biospecimens for 
biomarkersl
X
X
Urine Samples
Clinical safety 
(urinalysis)k
X
X
X
X
X
X
X
X
X
X
Xe
Banked biospecimens for 
biomarkersl
X
X
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Saliva Samples
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 179
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
Tissue Sample
Muscle Biopsy
Xee
Imaging Assessments
Echocardiogramm
X
X
Xe
Cardiac MRIaa
Xaa
Functional Assessments
FVCn,t
X
X
Xe
NSAAn
X
X
X
X
X
X
X
Ankle range of motion 
X
X
X
X
X
X
X
Ambulatory status
X
X
X
X
X
X
X
Actigraphyo
X
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentp
X
X
X
X
X
EQ-5D-Y Proxyp
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGp
X
X
X
X
X
X
X
Participant-completed
Modified PODCI –
Adolescentp
X
X
X
EQ-5D-Yp
X
X
X
PGISp
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 180
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
Clinical evaluator-completed
CGISn
X
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
X
X
WPAI:DMD Caregiver
X
X
X
Study Interventions
Protocol-mandated 
glucocorticoid regimenq
X
X












X
Background 
glucocorticoid regimen
X



Xv
Xv
IP administration
X
Ongoing monitoring
Concomitant medications




















X
Serious and nonserious 
adverse event monitoring




















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9= adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG = electrocardiogram; ELISpot= Enzyme-Linked ImmunoSpot; EQ-5D-Y= EuroQol 5 
Dimensions–Youth; FVC= Forced Vital Capacity; IP=investigational product; NAb=neutralizing antibodies; NSAA=North Star Ambulatory Assessment; PGIS= patient global 
impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; PR=pulse rate; temp=temperature.
a.
Visit 20 – Year 2, Week 1, Day 1

Prior to IP administration, the Investigator must confirm applicable Year 2 IP administration eligibility criteria (Section 7.1);
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 181
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20

Participants are to be admitted to the site;

Participants will be instructed not to take their background glucocorticoid dose on Day 390 (Visit 20);

The following assessments must be performed prior to IP administration: Physical examination, blood collection (ELISpot to mini-dystrophin and AAV9), urine 
sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone approximately 1 to 4 hours prior to infusion of IP;

IP administration over approximately 2 to 4 hours (-15 minutes or +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site for at least 7 additional days to enable prompt follow-up in the event of any emergent AEs through Day 403 (Visit 28), or longer if 
deemed necessary.

If the time between the blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned Day 390 Visit (Visit 20) exceeds 13 weeks 
(90 days), due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), then the 
clinical safety laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP. The participant will not be withdrawn due to exceeding the time 
between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20), as described in Section 7.1.

If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), a participant´s 
Year 2 IP administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be delayed for that participant until the pause is lifted. If the pause is not 
lifted within 6 months of the Day 360 (Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 ±7 days, and approximately every 6 
months afterwards until the pause is lifted (or more frequently if considered necessary by the investigator) for sites in Israel, see Appendix 16.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 182
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
b.
Visits 29, 29.2, 30.2, 31.2 and 32

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
c.
Visit 31 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern and/or participant 
preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood collection, may be 
performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory assessments must be collected as follows: 
Visit 31 (Year 2, Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
d.
Visit 42 and 43 – Long-term follow up Year 6

All participants will be followed for 5 years after receiving fordadistrogene movaparvovec. Therefore Visits 42 and 43 only apply to participants randomized to Cohort 2.
e.
Early Discontinuation Visit

This visit is not applicable for Cohort 2 participants who were withdrawn from the study between Day 360 (Visit 19) and Day 390 (Visit 20) (see Section 7).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 183
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical Safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only If the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
f.
Visit Windows for Visits 20 through Visit 43

The number of days between each visit for Visit 20 (Year 2, IP administration) through Visit 43 must be maintained irrespective of the actual visit day of Visit 20, eg, if 
the actual visit day at Visit 20 is 392 (instead of 390), then Visit 21 will take place on Day 393 (instead of Day 391), etc.
g.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable unless safety concerns warrant full examination.
h.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
i.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
j.
12 Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
k.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 
For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 184
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
If the time between the blood draw for the clinical safety laboratory tests on Visit 19 (Day 360) and the planned Visit 20 (Day 390) exceeds 13 weeks (90 days due to 
operational or administrative reasons [eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays]), then the clinical safety 
laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP, but the participant will not be withdrawn due to exceeding the time between Visit 
19 (Day 360) and the planned Visit 20 (Day 390), as described in Section 7.1.
l.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
m.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation.
n.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, range of motion and FVC may be video recorded at the annual visits. If 
CE re-training is required, the assigned master physiotherapist may request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments 
should be performed early in the course of the visit, to help reduce the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of 
assessments please consult the Functional Assessment Manual. On the following visits: Day 449 (Visit 31), Day 509 (Visit 33), Day 629 (Visit 34) and Day 749 (Visit 35), in 
which functional assessments (eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the 
functional test; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
o.
An activity monitor may be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
p.
COAs will be completed by the caregiver on behalf of the participant and/or the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
q.
Starting on Day 390 (Visit 20) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with 
the protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1). If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 185
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
review, operational issues causing significant delays), participants must delay Year 2 IP administration, they will not receive the protocol-mandated glucocorticoid regimen 
until the pause is lifted and Year 2 IP administration takes place; they will remain on their background glucocorticoid regimen until then.
r.
For eligibility for Year 2 IP administration please see Section 7.1.
s.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
t.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
u.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a particular matrix (sample type) will 
be stopped when at least 2 consecutive negative results are observed in that matrix.
v.
After two years (Day 749), any change to the background glucocorticoid regimen will be permitted (see Section 6.5.1).
w.
ELISpot to mini-dystrophin and AAV9 if a clinical event has occurred that, in the opinion of the Sponsor and/or the Investigator, could be due to an immunological reaction. 
If ELISpot is to be collected, these visits should be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. The 
following laboratory assessments must be collected as follows:
First day: NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase).
x.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 26 , will be sent 
to the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data. C3/C4 will also be sent to the central laboratory at Visits 23, 24, 25, 26 and 27. For 
more details please see Section 8.2.11 and Appendix 2.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 186
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,bb,
cc
Visit 
30bb,
cc
Visit 
30.2b,bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 6
Year 
2, 
Week 
1,
Day 7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 2, 
Week 4
Year 
2, 
Week 
5
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Approximate Blood 
Volume (ml)
11.5
11
11
7
7
7
7
11
12
4.5
14
3.5
16
3.5
6
8
7
12
6
20
y.
On Day 417 (Visit 29.2), only GLDH will be collected.
z.
ADA to mini-dystrophin only.
aa.
Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration (Section 2.3.3.7). If the site considers 
gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast administration will be performed. It is 
important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may be required in certain situations 
(Section 8.2.8). Only participants with a pre-IP administration cardiac MRI will have a follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
bb. Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not attend Visits 20 to 30.2 and therefore will not 
perform the corresponding tests and assessments. These participants will not receive their protocol-mandated glucocorticoid regimen at Year 2. For details on the 
retrospective assessment of exclusion criterion 15, please see Appendix 12, and Section 7.2.1.
cc.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not receive their protocol-mandated 
glucocorticoid regimen at Year 2. For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
dd. Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
ee.  A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo two post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-Baseline muscle biopsy cannot be scheduled on the 
day of Visit 19 or Visit 41, it may be performed at a later date, as long as it is at least 2 weeks before dosing, for the biopsy at Visit 19 and within 1 month of the day of the 
visit for the biopsy at Visit 41.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 187
10.10. Appendix 10: Japan Appendix
This appendix is only for investigators in Japan.
10.10.1. Schedule of Activities 
10.10.1.1. Schedule of Activities - Year 1 (Screening to Year 1 Day 360) 
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Informed 
consent/assent
X
Inform caregivers 
about study 
C3391007dd
X
Demography
X
Medical history
Xii
Medication 
history
X
Review of 
inclusion/exclusio
n criteria
X
X
Eligibility for 
Year 1 IP 
administrationv
X
Hospital stayjj
X




X
Physical 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 188
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Neurological 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
Weight
X
X
X
X
X
X
X
Height
X
X
X
X
X
X
Vital signs 
(supine BP, 
respiratory rate, 
PR, body temp, 
and O2 
saturation)i,j
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGk
X
X
X
X
X
X
CBCL
X
X
X
g
Randomization
Xbb
Laboratory Assessmentsl
Blood Samples
NAb
X
(X)cc
X
X
X
g
ADA to 
mini-dystrophi
n and AAV9
X
Xff
Xff
Xff
X
X
X
X
g
ELISpot to 
mini-
dystrophin and 
AAV9
X
X
X
g
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 189
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
g
Clinical safety 
(hematology, 
other)l
X
X
X
X
X
X
X
X
X
X
X
X
g
Chemistry and 
hepatic safety l
X
X
X
X
X
Xee
X
X
X
X
X
X
X
X
X
Post IP intensified 
safety 
monitoringl,w
X
X
X
X
X
Local and central 
laboratory 
testingaa
X
X
X
X
X
X
X
Cardiac Troponin 
I- central 
laboratory
X
X
X
X
X
X
X
X
X
X
X
X
Cardiac Troponin 
I or T-local 
laboratory
X
X
X
X
Xll
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 190
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
International 
normalized ratio 
(INR),
Hepatitis A virus 
(anti-HAV) 
immunoglobulin
M 
Hepatitis B 
surface antigen,
Hepatitis C 
antibodyl
X
X
Biomarker 
(creatine kinase) l
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked 
biospecimens for 
biomarkersm
X
X
X
Banked 
biospecimens for 
geneticsn
X
Urine Samples
Clinical safety 
(urinalysis)l
X
X
X
X
X
X
X
X
X
X
g
Banked 
biospecimens for 
biomarkersm
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 191
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Saliva Samples
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Tissue Samples
Muscle biopsyo
X
Xx
Imaging 
Assessments
Echocardiogramp
X
X
X
g
Cardiac MRIgg
Xhh
Xhh
Functional Assessments
FVCq,y
X
X
X
g
NSAAq
X
X
X
X
X
X
X
Ankle range of 
motion 
X
X
X
X
X
X
X
Ambulatory status
Xr
X
X
X
X
X
Actigraphys
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI 
– Pediatric Parentt
X
X
X
X
EQ-5D-Y Proxyt
X
X
X
EQ-5D-5L
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 192
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
PGIS:CGt
X
X
X
X
X
X
Participant-completed
EQ-5D-Yt
X
X
Clinical evaluator-completed
CGISq
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
WPAI:DMD 
Caregiver
X
Interventions
Protocol-
mandated 
glucocorticoid 
regimenu
X
X













X
Background 
glucocorticoid 
regimen
X
X
X




IP administration
X
Meningococcal 
vaccine
X
X
Ongoing 
monitoring
Concomitant 
medications
X





















X
Serious and 
nonserious 
X





















X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 193
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
adverse event 
monitoring 
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9=adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG=electrocardiogram; ELISpot=Enzyme-Linked ImmunoSpot; EQ-5D-Y=EuroQol 5 
Dimensions–Youth; FVC=Forced Vital Capacity; IP=investigational product; Men ACWY=Meningococcal serogroups A, C, W, and Y; NAb=neutralizing antibodies; 
NSAA=North Star Ambulatory Assessment; PGIS=patient global impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; temp=temperature; PR=pulse 
rate.Schedule of Activities – Year 2 and Long-Term Follow Up
a.
Visit 1 – Screening Visit 

During screening, participants and caregiver(s) will be assessed for study eligibility in accordance with the Inclusion/Exclusion Criteria as described in Section 5.1 and 
Section 5.2; 

Visit 1 must be conducted over the course of 2 days. The investigator will decide which of the schedules below they will follow and inform the study team:

Schedule A:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. Second day: should take place the next day or as soon as possible, 
after the first day: clinical safety (See Appendix 2), INR, cardiac troponin I.

Schedule B:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers and viral vector shedding. Second day: must take place only when the results of the test for 
NAb to AAV9 are available. The time between the first and second day of the Screening Visit is expected to be between 3-4 weeks (based on the time to 
obtain the results of the NAb to AAV9 test). Only participants with a negative test for NAb to AAV9 will perform the rest of the Visit 1 assessments as per 
SoA. This includes the collection of blood and urine for: clinical safety tests (see Appendix 2), INR and cardiac troponin I. Participants with a positive test for 
NAb to AAV9 will be screen failed and will not attend the second day of Screening Visit (Visit 1).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 194
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Informed consent must be provided by the caregiver(s). The participant may also be required to provide assent in compliance with local regulations and institutional
review board (IRB) requirements;

Screening blood tests with results considered by the Investigator to be transient and inconsistent with the participant’s clinical condition may be repeated once during the 
screening period for confirmation of eligibility;

Demographics: Information such as date of birth, race and ethnicity and gender will be collected in compliance with local regulations;

Medical history will include results of genetic testing for confirmation of diagnosis of DMD. Results must confirm the presence of an abnormality (eg, deletion, 
duplication), or a point mutation in the dystrophin gene(s) which is consistent with the diagnosis of DMD. The mutation type will be reported. If the Investigator 
determines that the results are inconclusive, a repeat genetic testing will be allowed through the central laboratory at Screening (Visit 1) prior to any other assessments. 
In that case participants may return for the remainder of Screening (Visit 1) once results are confirmed (Section 8.7.1);

Medical history will also be reviewed for any significant medical history and concurrent illness(es) that required or are requiring specialist consultation or treatment;

Medication history: Complete medication history will include all prescription or nonprescription drugs, and dietary and herbal supplements taken within 30 days prior to 
the Screening Visit (Visit 1). The date the participant first started glucocorticoids for their DMD and the date of start of the background glucocorticoid regimen that the 
participant is taking at the time of Visit 1 (Screening Visit) must also be documented. In addition, the general immunization status including the immunization status 
against meningococcus, and any other vaccine(s) required by the eculizumab local prescribing information, must be documented;

Meningococcal vaccine: Participants who have no contraindications and who have not previously received a MenACWY vaccination; or whose last vaccination at the 
time of the Screening Visit (Visit 1) is outside the time period of active coverage specified by the vaccine manufacturer (Visit 1) must receive at least one dose of 
MenACWY vaccine as early as possible in the Screening Period and not later than 30 days before IP administration (see Section 6.5.1). Participants must also receive 
MenB vaccination if indicated by national vaccination guidelines. In addition, local eculizumab prescribing information, including additional vaccination and other 
requirements must also be followed (see Section 6.5.1).

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 195
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
b.
Visit 14 and Visit 19 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern 
and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood 
collection, may be performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory samples must be collected: 
Visit 14 (Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
Visit 19 (Week 52)
First day: anti-HAV immunoglobulin M, Hepatitis B surface antigen, Hepatitis C antibody (these tests will not be applicable for Cohort 1 participants confirmed to 
meet exclusion criterion 15 [see Section 5.2]), NAb to AAV9, ADA to mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. 
Second day: clinical safety, INR, cardiac troponin I, biomarker (creatine kinase). 
c.
Visit 2 – Baseline Visit

Meningococcal vaccine: Only applicable for participants who have not received this vaccination at Screening (please refer to footnote a);

For sites outside the US, the Baseline visit should occur at least 31 calendar days prior to the planned IP administration visit, Day 1 (Visit 3), to allow for timely delivery 
of IP to the site, unless notified of earlier or later IP delivery by the study team. For US sites the Baseline visit should occur at least 16 calendar days prior to the planned 
IP administration visit, Day 1 (Visit 3), to allow for timely delivery of IP to the site, unless notified of earlier or later IP delivery by the study team; 

IP will be shipped to site following confirmation of participant’s eligibility (Section 5.1 and Section 5.2) and randomization. The amount of IP to be shipped to the site 
for IP administration at Visit 3 will be based on the measurement of body weight at the Baseline Visit (Visit 2). Body weight measurement must be verified by two site 
personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site.

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 196
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
d.
Visit 3 – Week 1, Day 1 (Day of IP administration)

Prior to IP administration, the Investigator must confirm applicable IP eligibility criteria (Section 6.1.1);

Participants will be instructed not to take their background glucocorticoid dose on Day 1 (Visit 3);

Participants are to be admitted to the site;

The following assessments must be performed prior to IP administration: physical examination, urine sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone 1 to 4 hours prior to infusion of IP; 

IP administration over approximately 2 to 4 hours (-15 minutes to +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved . Upon discharge, 
participants should stay near the site to enable prompt follow-up in the event of any emergent AEs through Day 14 (Visit 11), or longer if deemed necessary.
e.
Visits 12, 12.2, 13.2, 14.2 and 15

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
f.
Visit 18

This visit may be performed remotely (at or close to the participant’s home); in that case, it should include phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.

Amount of IP to be shipped to site for the IP administration on Day 390 (Visit 20) will be based on the measurement of body weight obtained at this visit. Body weight 
measurement must be verified by two site personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site. 
This visit is not applicable for Cohort 1 participants confirmed to meet exclusion criterion 15 (see Section 5.2).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 197
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be shipped to the site will be determined once the study has been 
restarted. Therefore, the weight collected at Day 328 (Visit 18) will not be entered into the interactive response technology drug management system during the dosing 
pause. Participants will be evaluated for Year 2 IP eligibility when the study is restarted.

May not be applicable for participants confirmed to meet exclusion criterion 15 or those who declined Year 2 IP administration (see Appendix 12 and Section 7.2.1).
g.
Early Discontinuation Visit

This visit is not applicable for participants who withdraw prior to Day 1 (Visit 3) or for Cohort 2 participants who are withdrawn from the study between Day 360 (Visit 
19) and Day 390 (Visit 20) (see Section 7.1).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only if the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
h.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable post-baseline unless safety concerns warrant full examination.
i.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
j.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 198
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
k.
12-Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
l.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 

For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 

On the following visits: Baseline Visit (Visit 2), Day 60 (Visit 14), Day 120 (Visit 16), Day 240 (Visit 17) and Day 360 (Visit 19), in which functional assessments 
(eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for 
additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
m.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
n.
Banked biospecimens for genetics are collected as described in Section 8.7.2.
o.
Open muscle biopsies will be obtained in approximately the first 15 participants randomized into Cohorts 1 and 2, and their siblings, at sites that have been trained and 
certified by the Sponsor/Sponsor designee to collect open muscle biopsies, following administration of an anesthetic (eg, regional block or under general anesthesia) 
according to institutional standard practice, and only after any imaging and functional assessments scheduled for the same visit have been completed. Baseline visit muscle 
biopsies will be performed after randomization. If a muscle biopsy cannot be scheduled on the day of the Baseline Visit, the biopsy may be performed at a later day, as long 
as it is at least 2 weeks before dosing.
p.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
q.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, ankle range of motion and FVC may be video recorded at the Day 1 
(Screening Visit), Baseline Visit (Visit 2), and at the annual visits (ie, Visits 19, 35, 37, 39, 41, 43). If CE re-training is required, the assigned master physiotherapist may 
request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be performed early in the course of the visit, to help reduce 
the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
r.
Ambulatory assessment at Screening (Visit 1) is based only on the ability to perform the 10 m run/walk, as assessed during the NSAA.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 199
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
s.
An activity monitor will be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
t.
COAs will be completed by the caregiver on behalf of the participant and/or by the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
u.
Starting on Day 1 (Visit 3) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1).
v.
For eligibility for Year 1 IP administration please see Section 6.1.1.
w.
For details regarding post IP intensified safety monitoring please see Section 8.2.10. For sites in Japan: haptoglobin will be analyzed by the local laboratory on Days 2 and 4 
(Visits 4 and 5).
x.
All participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo 2 post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-baseline muscle biopsy cannot be performed on 
the scheduled day, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing for the biopsy at Visit 19 and within 1 month of the day of the 
visit for the biopsy at Visit 41. 
y.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
z.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) only after IP administration, as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a 
particular matrix (sample type) will be stopped when at least 2 consecutive negative results are observed in that matrix. See Section 8.8.5 for additional details.
aa.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 9 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data.  C3/C4 will also be sent to the central laboratory at Visits 6, 7, 8, 9, and 10. For more 
details, please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 4 and 5, see Appendix 2 for details.
bb. In order to ensure an adequate understanding and management of potential safety risks, the initial rate of randomization into the study will be limited. No more than 2 
participants per week will be randomized at the start of the study, until 4 participants have been observed for at least 2 weeks post IP administration. After that, the rate could 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 200
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
be increased to no more than 3 participants randomized per week (until at total of 10 participants have been observed for at least 2 weeks post-IP administration). Thereafter, 
the rate of randomization could be further increased to no more than 5 participants randomized per week (until a total of 20 participants have been observed for at least 2 
weeks post-IP administration). After this time, no limits of the randomization rate will be imposed unless the study team, in consultation with the E-DMC, determines 
otherwise. For more details- please see Section 4.1.
cc.
The NAb to AAV9 blood samples at the Baseline Visit (Visit 2) will always be collected and sent to the Central Laboratory, but will only be analyzed and reviewed prior to 
Day 1 Visit (Visit 3) if the time between the first blood draw for NAb to AAV9 testing at the Screening Visit (Visit 1) or most recent test, if repeat blood draw(s) was required, 
and the Day 1 Visit (Visit 3) is expected to be more than 55 days, which is anticipated to occur rarely. Dosing cannot occur unless there is a negative test to AAV9 from a 
sample collected 55 or less days before the day of IP administration.
dd. For US sites, only when approved by the relevant Institutional Review Board.
ee.
On Day 28 (Visit 12.2), only GLDH will be collected.
ff.
ADA to mini-dystrophin only.
gg. The Investigator will discuss with the participant and caregiver the importance of having a baseline cardiac MRI, even under general anesthesia to be able to assess and 
manage potential cardiac adverse events during the study. This discussion and the decision to perform or not a baseline cardiac MRI will be documented in the participant’s 
records. A Participant requiring anesthesia or unable to undergo investigation with closed MRI (eg, metal implants) may be exempt, and will be allowed to be randomized in 
the study without a cardiac MRI. Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration 
(Section 2.3.3.7). If the site considers gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast 
administration will be performed. It is important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may 
be required in certain situations (Section 8.2.8).
hh. Cardiac MRI may be performed at any time between the first day of the Screening Visit (Visit 1) and the Day 1 Visit (Visit 3), and after randomization, as long as it is done 
before Day 1 (Visit 3). If a prior cardiac MRI was performed within 6 months of the Screening Visit (with gadolinium, or without gadolinium if contrast administration is 
contraindicated), and results are available, then a cardiac MRI at screening will not be performed. Only participants with a pre-IP administration cardiac MRI will have a 
follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
ii.
Participants will be assessed by a cardiologist at the Screening Visit, see Section 5.2, exclusion criteria 16 and 17.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 201
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
jj.
Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed 
necessary by the Investigator (see Section 8.2.10). 
kk. This visit is for sites in Germany only. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, 
this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone 
communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ll.
Cardiac troponin I or T will be analyzed by the local laboratory only on Day 8 (Visit 8). 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 202
10.10.1.2. Schedule of Activities – Year 2 and Long Term Follow Up 
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
Eligibility for Year 2 IP 
administrationr
X
Hospital staydd
X




X
Physical examinationg
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationg
X
X
X
X
X
X
X
X
X
X
X
X
Height and Weight
X
X
X
X
X
X
X
Vital signs (supine BP, 
respiration, PR, body 
temp, and O2 
saturation)h,i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGj
X
X
X
X
X
X
CBCL
X
X
X
Xe
Laboratory Assessmentsk
Blood Samples
 NAb to AAV9
X
X
X
Xe
  ADA to mini-
dystrophin and AAV9
Xz
Xz
Xz
X
X
X
X
Xe
  ELISpot to mini-
dystrophin and AAV9
X
X
Xw
Xe
Viral Vector Sheddingu
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 203
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
Clinical safety 
(hematology, other)k
X
X
X
X
X
X
X
X
X
X
X
X
Xe
Chemistry and hepatic 
safetyk
X
X
X
X
Xy
X
X
X
X
X
X
X
X
X
X
Post IP intensified 
safety monitoringk,s
X
X
X
X
X
Local and central 
laboratory testingx
X
X
X
X
X
X
X
Cardiac Troponin I-
central laboratory
X
X
X
X
X
X
X
X
X
X
X
X
X
Cardiac troponin I or T-
local laboratory
Xff
X
X
X
Xgg
X
Biomarker (creatine 
kinase)k
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked biospecimens 
for biomarkersl
X
X
Urine Samples
Clinical safety 
(urinalysis)k
X
X
X
X
X
X
X
X
X
X
Xe
Banked biospecimens 
for biomarkersl
X
X
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 204
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
Saliva Samples
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Tissue Sample
Muscle Biopsy
Xhh
Imaging Assessments
Echocardiogramm
X
X
Xe
Cardiac MRIaa
Xaa
Functional Assessments
FVCn,t
X
X
Xe
NSAAn
X
X
X
X
X
X
X
Ankle range of motion 
X
X
X
X
X
X
X
Ambulatory status
X
X
X
X
X
X
X
Actigraphyo
X
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentp
X
X
X
X
X
EQ-5D-Y Proxyp
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGp
X
X
X
X
X
X
X
Participant-completed
Modified PODCI –
Adolescentp
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 205
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
EQ-5D-Yp
X
X
X
PGISp
X
X
X
Clinical evaluator-completed
CGISn
X
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
X
X
WPAI:DMD Caregiver
X
X
X
Study Interventions
Protocol-mandated 
glucocorticoid regimenq
X
X













X
Background 
glucocorticoid regimen
X



Xv
Xv
IP administration
X
Ongoing monitoring
Concomitant 
medications





















X
Serious and nonserious 
adverse event 
monitoring





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9= adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG = electrocardiogram; ELISpot= Enzyme-Linked ImmunoSpot; EQ-5D-Y= EuroQol 5 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 206
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
Dimensions–Youth; FVC= Forced Vital Capacity; IP=investigational product; NAb=neutralizing antibodies; NSAA=North Star Ambulatory Assessment; PGIS= patient global 
impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; PR=pulse rate; temp=temperature.
a.
Visit 20 – Year 2, Week 1, Day 1

Prior to IP administration, the Investigator must confirm applicable Year 2 IP administration eligibility criteria (Section 7.1);

Participants are to be admitted to the site;

Participants will be instructed not to take their background glucocorticoid dose on Day 390 (Visit 20);

The following assessments must be performed prior to IP administration: Physical examination, blood collection (ELISpot to mini-dystrophin and AAV9), urine sample 
collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone approximately 1 to 4 hours prior to infusion of IP; 

IP administration over approximately 2 to 4 hours (-15 minutes or +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital stay. 
Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site for at least 7 additional days to enable prompt follow-up in the event of any emergent AEs through Day 403 (Visit 28), or longer if 
deemed necessary.

If the time between the blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned Day 390 Visit (Visit 20) exceeds 13 weeks 
(90 days), due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), then the 
clinical safety laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP. The participant will not be withdrawn due to exceeding the time 
between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20), as described in Section 7.1.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 207
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f

If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), a participant’s Year 
2 IP administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be delayed for that participant until the pause is lifted. If the pause is not lifted 
within 6 months of the Day 360 (Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 ±7 days, and approximately every 6 months 
afterwards until the pause is lifted (or more frequently if considered necessary by the investigator) for sites in Israel, see Appendix 16.
b.
Visits 29, 29.2, 30.2, 31.2, and 32 

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
c.
Visit 31 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern and/or participant 
preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood collection, may be 
performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory assessments must be collected as follows: 
Visit 31 (Year 2, Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
d.
Visit 42 and 43 – Long-term follow up Year 6

All participants will be followed for 5 years after receiving fordadistrogene movaparvovec. Therefore Visits 42 and 43 only apply to participants randomized to Cohort 2.
e.
Early Discontinuation Visit 

This visit is not applicable for Cohort 2 participants who were withdrawn from the study between Day 360 (Visit 19) and Day 390 (Visit 20) (see Section 7).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 208
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical Safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only If the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
f.
Visit Windows for Visits 20 through Visit 43 

The number of days between each visit for Visit 20 (Year 2, IP administration) through Visit 43 must be maintained irrespective of the actual visit day of Visit 20, eg, if 
the actual visit day at Visit 20 is 392 (instead of 390), then Visit 21 will take place on Day 393 (instead of Day 391), etc.
g.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable unless safety concerns warrant full examination.
h.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
i.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
j.
12 Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
k.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2).
For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 209
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
If the time between the blood draw for the clinical safety laboratory tests on Visit 19 (Day 360) and the planned Visit 20 (Day 390) exceeds 13 weeks (90 days due to 
operational or administrative reasons [eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays]), then the clinical safety 
laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP, but the participant will not be withdrawn due to exceeding the time between Visit 19 
(Day 360) and the planned Visit 20 (Day 390), as described in Section 7.1.
l.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
m.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized
interpretation. 
n.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, range of motion and FVC may be video recorded at the annual visits. If 
CE re-training is required, the assigned master physiotherapist may request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments 
should be performed early in the course of the visit, to help reduce the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of 
assessments please consult the Functional Assessment Manual. On the following visits: Day 449 (Visit 31), Day 509 (Visit 33), Day 629 (Visit 34) and Day 749 (Visit 35), in 
which functional assessments (eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the 
functional test; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
o.
An activity monitor may be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
p.
COAs will be completed by the caregiver on behalf of the participant and/or the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
q.
Starting on Day 390 (Visit 20) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1). If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 210
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
review, operational issues causing significant delays), participants must delay Year 2 IP administration, they will not receive the protocol-mandated glucocorticoid regimen 
until the pause is lifted and Year 2 IP administration takes place; they will remain on their background glucocorticoid regimen until then.
r.
For eligibility for Year 2 IP administration please see Section 7.1.
s.
For details regarding post IP intensified safety monitoring please see Section 8.2.10. For sites in Japan: haptoglobin will be analyzed by the local laboratory on Days 391 and 
393 (Visits 21 and 22) in Year 2.
t.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
u.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a particular matrix (sample type) will 
be stopped when at least 2 consecutive negative results are observed in that matrix.
v.
After two years (Day 749), any change to the background glucocorticoid regimen will be permitted (see Section 6.5.1).
w.
ELISpot to mini-dystrophin and AAV9 if a clinical event has occurred that, in the opinion of the Sponsor and/or the Investigator, could be due to an immunological reaction. 
If ELISpot is to be collected, these visits should be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. The 
following laboratory assessments must be collected as follows:
First day: NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase).
x.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 26 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data. C3/C4 will also be sent to the central laboratory at Visits 23, 24, 25, 26 and 27.  For 
more details please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 21 and 22, see Appendix 2 for 
details.
y.
On Day 417 (Visit 29.2), only GLDH will be collected.
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
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Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
z.
ADA to mini-dystrophin only.
aa.
Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration (Section 2.3.3.7). If the site considers 
gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast administration will be performed. It is 
important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may be required in certain situations 
(Section 8.2.8). Only participants with a pre-IP administration cardiac MRI will have a follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35). 
bb. Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not attend Visits 20 to 30.2 and therefore will not 
perform the corresponding tests and assessments. These participants will not receive their protocol-mandated glucocorticoid regimen at Year 2. For details on the retrospective 
assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
cc.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not receive their protocol-mandated glucocorticoid 
regimen at Year 2. For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
dd. Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
ee.
This visit is for sites in Germany only. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, 
this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone 
communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ff.
Cardiac troponin I or T by the local laboratory to be collected pre-IP administration.
gg. Cardiac troponin I or T to be analyzed by the local laboratory only on Day 397 (Visit 25).
hh.   A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo two post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-Baseline muscle biopsy cannot be scheduled on the 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 212
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb, cc& 
26bb, cc
Visit 
27bb, cc
Visit 
28bb, cc
Visit 
29b, bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb, cc
Visit 
30.1ee
,bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,
cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 39, 
41, 43d
Year 2, 
Week 1, Day 
1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Week 
1, 
Day 4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 2, 
Week 2, 
Days 8 
&9
Year 
2, 
Week 
2, Day 
10
Year 
2, 
Week 
2, Day 
14
Year 
2, 
Week 
3
Year 
2, 
Wee
k 4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 5, 
6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f,c
3f
3f
7f
7f
7f
30f
30f
day of Visit 19 or Visit 41, it may be performed at a later date, as long as it is at least 2 weeks before dosing, for the biopsy at Visit 19 and within 1 month of the day of the 
day of the visit for the biopsy at Visit 41. 
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PFIZER CONFIDENTIAL
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10.10.2. Study Intervention Definition (per Japanese regulation)
Defect: Refers to lack of function of the study intervention (see Section 6.1), causing 
generally poor conditions where the cells cause adverse reactions that affects the human 
body) irrespective of what stage of manufacture, delivery, storage or use the defect occurs.
10.10.2.1. Reporting Criteria
Study intervention defects are to be reported to the sponsor within 24 hours of investigator 
awareness (see Section 10.10.1.2) if any of the points listed below apply. Note: The reporting 
of study intervention defects will not result in any change to the reporting of AEs as 
described in Section 10.3 (Appendix 3).

Occurrence of study intervention defects directly or indirectly leads to SAE(s) (see 
Section 10.3.2) of a participant/user/other person.
OR

Study intervention defects have not actually led to SAE(s) but may possibly lead to 
SAE(s) of a participant/user/other person.
For product complaints that do not meet the reporting criteria above, refer to the 
Investigational Product Complaints section of the study IP Manual for detailed reporting 
procedures.
10.10.2.2. Reporting Procedures
The following procedures are to be followed in order to report the Study Intervention 
Defect(s) to the Sponsor:
1. Study intervention defects information should be recorded, as completely as possible on 
the Investigational Drug Product (Regenerative medicine products) Complaint 
Submission Form located in the Investigator Site File.
The form should be submitted electronically lo sponsor within 24 hours of being aware of an 
intervention defect.
After the complaint is received by the Sponsor, a close out memo will be generated. This 
close out memo will be provided to the study site.
10.10.3. Study Design
In order to ensure an adequate understanding and management of potential safety risks, the 
initial rate of randomization into the study will be limited. No more than 2 participants per 
week will be randomized at the start of the study, until 4 participants have been observed for 
at least 2 weeks post-IP administration. After that, the rate could be increased to no more 
than 3 participants randomized per week (until at total of 10 participants have been observed 
for at least 2 weeks post-IP administration). Thereafter, the rate of randomization could be 
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Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
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Page 214
further increased to no more than 5 participants randomized per week (until a total of 
20 participants have been observed for at least 2 weeks post IP-administration). After this 
time, no limits to the randomization rate will be imposed unless the study team, in 
consultation with the E-DMC, determines otherwise. Ongoing blinded review of safety data 
will be conducted by the study team, and frequent periodic unblinded reviews of safety data 
will be conducted by the E-DMC, as described in detail in the E-DMC charter. Sites in Japan 
must ensure at least 14 days between IP administration for consecutive participants.
10.10.4. Post IP Intensified Safety Monitoring (at Year 1 and Year 2)
Due to the potential for an immune reaction against the AAV9 vector and/or the transgene, 
participants will undergo an intensified safety monitoring period for the first 34 days after IP 
administration in Year 1 and in Year 2.
Following IP administration, participants will be monitored as inpatients for at least 7 days, 
or longer, if deemed necessary by the Investigator (see SoA for details). Participants must be 
in an individual room, ie, not shared with other patients. Volume status should be assessed 
regularly, and if a participant experiences nausea or vomiting, consideration should be given 
to the placement of an IV line for treatment with an IV anti-emetic, hydration and 
replacement of the oral protocol-mandated glucocorticoid regimen by an IV regimen (see 
Section 6.5.1). Upon discharge, participants will be asked to stay local to the site (ie, if they 
do not live near the site, they will be asked to stay in at an overnight facility) for at least 14 
days, or longer, if deemed necessary by the Investigator. Participants randomized from sites 
in Japan will be admitted to hospital for at least 14 days after IP administration and will be 
discharged if there are no ongoing adverse events that require medical management. On the 
day of IP administration, if adverse events possibly related to IP administration are observed, 
participants should not be discharged until the events have resolved.
10.10.5. Regulatory Reporting Requirements for SAEs
The sponsor will report SAEs that impact study status, or were deemed life-threatening, to 
the Japan sites within approximately 24 hours of Pfizer Japan receipt of the report.
10.10.6. Reporting of Safety Issues and Serious Breaches of the Protocol or ICH GCP
In the event of any prohibition or restriction imposed (ie, clinical hold) by an applicable 
regulatory authority in any area of the world, or if the investigator is aware of any new 
information that might influence the evaluation of the benefits and risks of the investigational 
product, Pfizer should be informed immediately. This information should be shared with 
Japan sites approximately 24 hours after Pfizer Japan is aware of this information.
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10.10.7. Study Intervention(s) Administered
Intervention Name
fordadistrogene movaparvovec
Placebo for fordadistrogene 
movaparvovec
Type
Gene Therapy
Placebo for Gene Therapy
Use
Experimental
Placebo
IMP and NIMP/AxMP
IMP
IMP
Dose Formulation
Sterile Solution for Infusion
Sterile Solution for Infusion
Unit Dose Strength(s)
1E14 vg/mL
Note: This is the nominal 
concentration of the IP; for lot 
specific dosing calculation, the exact 
strength of each lot will be provided.
For nominal dosing, 1E14 vg/mL will 
be the concentration used for the 
calculation of the administered dose. 
Nominal dosing will only be 
implemented for Year 2 IP 
administration. The Sponsor will 
communicate to the sites what dosing 
strategy must be implemented for 
each participant to be dosed. (Refer to 
IP Manual for further details) 
0 vg/mL
Dosage Level(s) 
2E14 vg/kg 
Single dose IV infusion
0 vg/kg
Single dose IV infusion
Route of Administration
Intravenous Infusion
Intravenous Infusion
Sourcing
Provided centrally by the Sponsor 
(Refer to IP Manual for further 
details)
Provided centrally by Sponsor (Refer 
to IP Manual for further details)
Packaging and Labeling
Study intervention will be provided as 
5 mL per vial (5 mL/vial). Each vial 
will be labeled as required per 
country requirement
Study intervention will be provided as 
5 mL per vial (5 mL/vial). Each vial 
will be labeled as required per 
country requirement
SRSD
IB
IB
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Study Intervention(s)
Interventio
n Name
IV 
methylprednisolon
e
Oral prednisone or 
prednisolone
Deflazacort
Eculizumab
Antiemetics 
eg. ondansetron
MenACWY Vaccine
Type
Drug
Drug
Drug
Drug
Drug
Vaccine 
Use
One-time, pre-
administration of 
IP, Year 1 and 
Year 2
Background glucocorticoid 
regimen pre- IP 
administration and after 
completion of 90-day 
Protocol-mandated 
glucocorticoid regimen for at 
least the first 2 years in the 
study. Protocol-mandated 
post-IP dosing for 90 days
Background 
glucocorticoid regimen 
pre- IP administration 
and after completion of 
90-day Protocol-
mandated 
glucocorticoid regimen 
for at least the first 2 
years in the study
Medication to treat 
adverse events (aHUS), 
to be administered at 
the discretion of the 
Investigator. Guidance 
for use provided in 
Section 6.5.1
Medication to prevent 
or treat adverse events 
(nausea and/or 
vomiting), to be 
administered at 
discretion of 
Investigator. See 
Section 6.5.1
Required per 
eculizumab label. 
Must be administered 
no later than 30 days 
before and only after 
60 post- IP 
administration. See 
Section 6.5.1
IMP or 
NIMP/Ax
MP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
NIMP/AxMP
Dose 
Formulatio
n
Sterile solution for 
injection
Tablets or Oral Suspension
Tablet or Oral 
suspension
Sterile Solution for 
Infusion
Orally disintegrating 
tablet or sterile solution 
for injection
Solution for injection
Unit Dose 
Strength(s)
40 mg/mL
1 mg, 2 mg or 5 mg
Tablets: 6 mg, 18 mg, 
30 mg or 36 mg
Oral Suspension: 22.75 
mg/mL
300 mg concentrate (10 
mg/ml)
Tablet: 4 mg or 8 mg
Injection: 2mg/mL
10 mcg group A, 
5 mcg group C, 
5 mcg group W-135,
5 mcg group Y 
Dosage 
Level(s)
2 mg/kg
At least 0.5 mg/kg/day
At least 0.75 mg/kg/day
Total dose to be 
determined by the
investigator
Total dose to be 
determined by the 
investigator
Single dose injection 
(0.5mL)
Route of 
Administra
tion
Intravenous 
infusion 
Oral
Oral 
Intravenous Infusion
Oral/ injection/IV 
infusion
Intramuscular 
injection
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Study Intervention(s)
Sourcing
Sourced by the 
clinical site using 
locally approved 
product or 
provided to the site 
by local vendors 
coordinated by the 
Sponsor 
Sourced by the clinical site 
using locally approved 
product or provided to the 
site by local vendors 
coordinated by the Sponsor
Sourced by the clinical 
site using locally 
approved product or 
provided to the site by 
local vendors 
coordinated by the 
Sponsor 
The sponsor will 
provide initial safety 
stock then remaining 
supply to be sourced by 
the clinical site using 
locally approved
product unless 
otherwise arranged with 
the sponsor
Sourced by the clinical 
site using locally 
approved product or 
provided to the site by 
local vendors 
coordinated by the 
Sponsor 
Sourced by the 
clinical site using 
locally approved 
product or provided 
to the site by local 
vendors coordinated 
by the Sponsor 
Packaging 
and 
Labeling
Study intervention 
will be provided as 
locally approved 
product and 
labeled as required 
per country and 
site requirements
Study intervention will be 
provided as locally approved 
product and labeled as 
required per country and site 
requirements 
Study intervention will 
be provided as locally 
approved product and 
labeled as required per 
country and site 
requirements
Study intervention will 
be provided as 300 
mg/30mL (10mg/mL) 
vial concentrated 
solution for intravenous 
infusion.  Product will 
be labeled as required 
per country and site 
requirements.
Study intervention will 
be provided as locally 
approved product and 
labeled as required per 
country and site 
requirements
Study intervention 
will be provided as 
locally approved 
product and labeled 
as required per 
country and site 
requirements
SRSD
SmPC
SmPC
SmPC
SmPC
SmPC
SmPC
Of the study interventions listed in the table above:  IV methylprednisolone, oral prednisone, or prednisolone, deflazacort, eculizumab, 
antiemetics e.g., ondansetron and MenACWY vaccine are not subject to safety reporting in accordance with Japanese regulation 
requirements.
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10.10.8. Clinical Laboratory Tests
Table 4.
Protocol Required Safety Laboratory Assessments
CENTRAL LABORATORY TESTING
Clinical Safety
Hematology
Urinalysis
Other
Hemoglobin
Hematocrit
Red blood cell (RBC) count and 
morphology
Platelet count
White blood cell count (and 
morphology as applicable)
Total neutrophils (Abs)
Absolute neutrophils
Eosinophils (Abs)
Monocytes (Abs)
Basophils (Abs)
Lymphocytes (Abs)
Red blood cell indices (mean 
corpuscular volume, mean corpuscular 
hemoglobin, mean corpuscular 
hemoglobin concentration)
pH
Glucose (qual)
Protein (qual)
Blood (qual)
Ketones
Nitrites
Leukocyte esterase
Microscopy and culturea
Prothrombin time (PT)
activated partial 
thromboplastin time
C-reactive protein
Lipase
Amylase
Cystatin C
Haptoglobinb
Chemistry and Hepatic Safety
BUN and Creatinine
Glucose
Calcium
Sodium
Potassium
Chloride
Total CO2 (Bicarbonate)
AST, ALT
Total Bilirubin (direct and indirect bilirubin)
Alkaline phosphatase
Uric Acid
Albumin
Total protein
Serum Phosphorus
Gamma glutamyl transferase (GGT)
Glutamate dehydrogenase (GLDH)
For Screening (Visit 1) and Day 360 (Visit 19) Only
International normalized ratio (INR)
Hepatitis A virus (anti-HAV) immunoglobulin M
Hepatitis B surface antigen
Hepatitis C antibody
For Post IP Intensified Safety Monitoring (at Year 1 and Year 2)
Complement biomarkers eg, C3 and C4, additional exploratoryc
Haptoglobin- analyzed by local laboratory on Days 2 and 4 (Visits 4 and 5) in Year 1 and on Days 391 and 
393 (Visits 21 and 22) in Year 2 for sites in Japan.
Urine biomarkers
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Table 4.
Protocol Required Safety Laboratory Assessments
Other Assessments
Immunogenicity: NAb to AAV9; ELISpot to AAV9; ADA to AAV9; ELISpot to mini-dystrophin; 
ADA to mini-dystrophin
Viral vector shedding (whole blood, saliva, and urine)
Cardiac troponin I 
Creatine kinase
Conditional Testing
Genetic screening for aHUS-Central Laboratory, if needed as per Section 6.5.1
Local assessment of NT-ProBNP/BNP, if needed as per Section 8.2.7
LOCAL AND CENTRAL LABORATORY TESTING
Local Laboratory
Hematology: as per clinical safety panel, 
including blood smear for morphology. 
Absolute neutrophils are not required.
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Chemistry and hepatic safety: at a 
minimum, creatinine, BUN (or blood urea if 
BUN cannot be performed), calcium, 
sodium, potassium, chloride, total CO2 
(bicarbonate), uric acid and serum 
phosphorus; but excluding AST and ALT-
sensitive clinical data
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cystatin C (when possible)
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Urinalysis: as per clinical safety panel
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cardiac troponin I, (or cardiac troponin 
T if cardiac troponin I is not available)
Baseline Visit (Visit 2), Day 2 (Visit 4), Day 4 (Visit 5), 
Day 6 (Visit 6), Day 8 (Visit 8), and Day 10 (Visit 10) in 
Year 1
Day 390 (Visit 20), Day 391 (Visit 21), Day 393 (Visit 22), 
Day 395 (Visit 23), Day 397 (Visit 25), and Day 399 (Visit 
27) in Year 2
Serum creatinine
Baseline Visit, Day 2 and Day 4 (Visits 2, 4, and 5) in Year 
1
Day 390 to Day 393 (Visits 20 to 22) in Year 2
Local Laboratory for Japan Only
Local labs as described above 
Day 2 to Day 10 (Visit 4 to Visit 10) in Year 1
Day 391 to Day 399 (Visits 21 to 27) in Year 2
Haptoglobin (mandatory)
Other- prothrombin time
activated partial thromboplastin time, 
CRP, amylase, lipase (when possible)
Day 2 and Day 4 (Visit 4 and Visit 5) in Year 1
Day 391 and Day 393 (Visits 21 and 22) in Year 2
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Table 4.
Protocol Required Safety Laboratory Assessments
Central Laboratory
Clinical safety (not for Japan)
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
Chemistry and hepatic safety (not for 
Japan)
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
Urinalysis (not for Japan)
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
GLDH
Day 9 (Visit 9) at Year 1
Day 398 (Visit 26) at Year 2
For sites in Japan additionally on Day 2 (Visit 4), Day 4 
(Visit 5) in Year 1, and on Day 391 (Visit 21) and Day 393 
(Visit 22) in Year 2
C3, C4
Days 6 to 10 (Visits 6 to 10) at Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cardiac troponin I
Day 7 (Visit 7) at Year 1
Day 396 (Visit 24) at Year 2
Day 42 (Visit 13.1) only for Germany)
Day 431 (Visit 30.1 only for Germany)
a.
Only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. Culture to be done 
locally.
b.
Only for the Screening Visit (Visit 1) and for Day 360 Visit (Visit 19).
c.
Additional biomarkers, such as ferritin, will be included so long as blood volume limits are not 
exceeded.
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10.11. Appendix 11: Alternative Measures During Public Emergencies
The alternative study measures described in this section are to be followed during public 
emergencies, including the COVID-19 pandemic. This appendix applies for the duration of 
the COVID-19 pandemic and will become effective for other public emergencies only upon 
written notification from Pfizer.
Use of these alternative study measures are expected to cease upon the return of business as 
usual circumstances (including the lifting of any quarantines and travel bans/advisories).
10.11.1. Telehealth Visits
In the event that in-clinic study visits cannot be conducted, every effort should be made to 
follow-up on the safety of study participants at scheduled visits per the SoA or unscheduled 
visits. Telehealth visits may be used, if/when it is not possible to have home visits conducted 
by a home healthcare service (see Section 10.11.3), to continue to assess participant safety 
and collect data points. Telehealth includes the exchange of healthcare information and 
services via telecommunication technologies (eg, audio, video, video-conferencing software) 
remotely, allowing the participant and the investigator to communicate on aspects of clinical 
care, including medical advice, reminders, education, and safety monitoring. The following 
assessments must be performed during a telehealth visit:

Review and record any AEs and SAEs since the last contact. Refer to Section 8.3.

Review and record any new concomitant medications or changes in concomitant 
medications since the last contact.
Study participants must be reminded to promptly notify site staff about any change in their 
health status.
10.11.2. Alternative Facilities for Safety Assessments
10.11.2.1. Laboratory Testing
If a study participant is unable to visit the site for protocol-specified safety laboratory 
evaluations, testing may be conducted at a local laboratory if permitted by local regulations. 
The local laboratory may be a standalone institution or within a hospital. The following 
safety laboratory evaluations may be performed at a local laboratory (see Appendix 2):

Hematology panel

Chemistry panel; please note that the results of CK, AST and ALT should not be made 
available to the study site and Sponsor (see Section 6.3.3)

Urinalysis

Other (as defined in Table 3 in Appendix 2).
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If a local laboratory is used, qualified study site personnel must order, receive, and review 
results. Site staff must collect the local laboratory reference ranges and 
certifications/accreditations for filing at the site. Laboratory test results are to be provided to 
the site staff as soon as possible.  The local laboratory reports should be filed in the 
participant’s source documents/medical records. Relevant data from the local laboratory 
report should be recorded on the CRF. 
10.11.3. Home Health Visits
A home health care service will be utilized to facilitate scheduled visits per the SoA. Home 
health visits include a healthcare provider conducting an in-person study visit at the 
participant’s location, rather than an in-person study visit at the site. The following may be 
performed during a home health visit:

Blood draws

Urine sample collection

Vital signs
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10.12. Appendix 12: Retrospective Assessment of Exclusion Criterion 15
10.12.1. Retrospective Assessment of Original Exclusion Criterion 15
Original exclusion criterion 15:
1. Participants with the following genetic abnormalities in the dystrophin gene as confirmed 
by the investigator based on the review of DMD genetic testing:
a.
Any mutation (exon deletion, exon duplication, insertion, or point mutation) affecting 
any exon between exon 9 and exon 13, inclusive; OR
b. A deletion that affects both exon 29 and exon 30.
For participants who had started, or completed the Screening Visit (Visit 1), but were not 
randomized, exclusion criterion 15 will be assessed as part of the study eligibility 
assessment.
For participants randomized, but who have not yet received IP, the investigator will review 
the results of the genetic testing, and will withdraw from the study any participant who meets 
exclusion criterion 15 (see Section 7.2).
For participants who have already received IP, the unblinded medical monitor will review the 
results of the genetic testing to determine that:
2. Participants in Cohort 1 who meet exclusion criterion 15 will remain in the study for 
safety monitoring; but will not receive placebo in Year 2 (Section 7.1). Therefore, these 
participants will not require the post-IP safety monitoring in Year 2, will not attend 
Visit 18 in Year 1 and Visits 20 to 30.2 in Year 2, but will attend all subsequent visits; 
they will not receive their protocol-mandated glucocorticoid regimen in Year 2. Please 
find additional details in Sections 1.3.1; 1.3.2; 5.2; 6.5.1; 6.5.2; 7.1; and 8.2.10.
3. Participants in Cohort 2 who meet exclusion criterion 15 will be confirmed to be not 
eligible for Year 2 IP administration and will be withdrawn from the study immediately 
upon determination of ineligibility.
10.12.2. Retrospective Assessment of Updated Exclusion Criterion 15
Updated exclusion criterion 15:
1. Participants with the following genetic abnormalities in the dystrophin gene as 
confirmed by the investigator based on the review of DMD genetic testing:
a.
Any mutation (exon deletion, exon duplication, insertion, or point mutation) 
affecting any exon between exon 9 and exon 13, inclusive; OR
b. A deletion that affects both exon 29 and exon 30; OR
c.
A deletion that affects any exons between 56-71, inclusive.
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
For current study participants who have not yet received investigational product (ie, 
those screened/randomized but not dosed) the investigator will review the results of 
the genetic test and determine if the updated exclusion criterion 15 is met.
o
Participants screened but not randomized who meet the updated exclusion 
criterion 15 must be screen failed. 
o
Participants randomized but not dosed who meet the updated exclusion 
criterion 15 must be discontinued from the study.
o
Participants screened/randomized but not dosed who do not meet the updated 
exclusion criterion 15 will continue with the protocol visits and procedures. 

For participants who have already received Year 1 IP, (but not Year 2 IP), the 
unblinded medical monitor will review the results of the genetic testing to determine 
that:
o
Participants in Cohort 1 who meet the newly defined exclusion criterion 15 
will remain in the study for safety monitoring but will not receive placebo in 
Year 2 (see Section 7.1). Therefore, these participants will not require the 
post-IP safety monitoring in Year 2, will not attend Visit 18 in Year 1 and 
Visits 20 to 30.2 in Year 2, but will attend all subsequent visits; they will not 
receive their protocol-mandated glucocorticoid regimen in Year 2. Please find 
additional details in Section 1.3.1; Section 1.3.2; Section 5.2; Section 6.5.1; 
Section 6.5.2; Section 7.1; and Section 8.2.10.
o
Participants in Cohort 2 who meet exclusion criterion 15 will be confirmed to 
be not eligible for Year 2 IP administration and will be withdrawn from the 
study immediately upon determination of ineligibility.

Participants who have already received Year 2 IP will remain in the study even if the 
investigator confirms that the updated exclusion criterion 15 is met. In that case a 
very close follow up for signs/symptoms of myositis will be performed, especially 
during the first 3 months post IP administration. 
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10.13. Appendix 13: DMD Long-Term Safety and Effectiveness Follow-Up PASS Study
To evaluate the longer term safety and efficacy of fordadistrogene movaparvovec, the 
sponsor plans to conduct a post-approval, non-interventional Registry study. Participants in 
the Registry will include participants who have completed 5 years of follow-up post 
administration of fordadistrogene movaparvovec in any of the sponsor studies (Phase 1b, 2, 
or 3), and newly treated patients in the post-marketing setting. The sponsor anticipates that 
the follow up in the post-approval Registry study will be 10 years and therefore participants 
treated within a sponsor study would be followed for a total of 15 years after dosing with 
fordadistrogene movaparvovec, while patients treated in the post-marketing setting will have 
10 years of follow up.
Safety and efficacy information is expected to be collected on a yearly basis, and may 
include demographic information, assessment of muscle strength, ambulation status, the 
NSAA to assess lower limb function, the PUL 2.0 to assess upper limb function, ventilation 
status, pulmonary function testing, and evaluation of cardiac function with echocardiogram 
or cardiac MRI.
Details of this study will be included in a separate protocol.
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10.14. Appendix 14: Germany-Specific Country Amendment
This appendix is only for investigators in Germany.
10.14.1. Schedule of Activities – Year 1
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Informed 
consent/assent
X
Inform caregivers 
about study 
C3391007dd
X
Demography
X
Medical history
Xii
Medication 
history
X
Review of 
inclusion/exclusio
n criteria
X
X
Eligibility for 
Year 1 IP 
administrationv
X
Hospital stayjj
X




X
Physical 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Weight
X
X
X
X
X
X
X
Height
X
X
X
X
X
X
Vital signs 
(supine BP, 
respiratory rate, 
PR, body temp, 
and O2 
saturation)i,j
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGk
X
X
X
X
X
X
CBCL
X
X
X
g
Randomization
Xbb
Laboratory Assessmentsl
Blood Samples
Nab
X
(X)cc
X
X
X
g
ADA to 
mini-dystrophi
n and AAV9
X
Xff
Xff
Xff
X
X
X
X
g
ELISpot to 
mini-
dystrophin and 
AAV9
X
X
X
g
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
g
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Clinical safety 
(hematology, 
other)l
X
X
X
X
X
X
X
X
X
X
X
X
g
Chemistry and 
hepatic safety l
X
X
X
X
X
Xee
X
X
X
X
X
X
X
X
X
Post IP intensified 
safety 
monitoringl,w
X
X
X
X
X
Local and central 
laboratory 
testingaa
X
X
X
X
X
X
X
Cardiac Troponin 
I
X
X
X
X
X
X
X
X
X
X
X
X
International 
normalized ratio 
(INR),
Hepatitis A virus 
(anti-HAV) 
immunoglobulin
M 
Hepatitis B 
surface antigen,
Hepatitis C 
antibodyl
X
X
Biomarker 
(creatine kinase) l
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Banked 
biospecimens for 
biomarkersm
X
X
X
Banked 
biospecimens for 
geneticsn
X
Urine Samples
Clinical safety 
(urinalysis)l
X
X
X
X
X
X
X
X
X
X
g
Banked 
biospecimens for 
biomarkersm
X
X
X
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Saliva Samples
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Tissue Samples
Muscle biopsyo
X
Xx
Imaging 
Assessments
Echocardiogramp
X
X
X
g
Cardiac MRIgg
Xhh
Xhh
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 230
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Functional Assessments
FVCq,y
X
X
X
g
NSAAq
X
X
X
X
X
X
X
Ankle range of 
motion 
X
X
X
X
X
X
X
Ambulatory status
Xr
X
X
X
X
X
Actigraphys
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI 
– Pediatric Parentt
X
X
X
X
EQ-5D-Y Proxyt
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGt
X
X
X
X
X
X
Participant-completed
EQ-5D-Yt
X
X
Clinical evaluator-completed
CGISq
X
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 231
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Health economic questionnaires
HRU:CG
X
WPAI:DMD 
Caregiver
X
Interventions
Protocol-
mandated 
glucocorticoid 
regimenu
X
X













X
Background 
glucocorticoid 
regimen
X
X
X




IP administration
X
Meningococcal 
vaccine
X
X
Ongoing 
monitoring
Concomitant 
medications
X





















X
Serious and 
nonserious 
adverse event 
monitoring 
X





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9=adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG=electrocardiogram; ELISpot=Enzyme-Linked ImmunoSpot; EQ-5D-Y=EuroQol 5 
Dimensions–Youth; FVC=Forced Vital Capacity; IP=investigational product; Men ACWY=Meningococcal serogroups A, C, W, and Y; Nab=neutralizing antibodies; 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 232
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
NSAA=North Star Ambulatory Assessment; PGIS=patient global impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; temp=temperature; PR=pulse 
rate.Schedule of Activities – Year 2 and Long-Term Follow Up
a.
Visit 1 – Screening Visit 

During screening, participants and caregiver(s) will be assessed for study eligibility in accordance with the Inclusion/Exclusion Criteria as described in Section 5.1 and 
Section 5.2; 

Visit 1 must be conducted over the course of 2 days. The investigator will decide which of the schedules below they will follow and inform the study team:

Schedule A:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, Nab to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. Second day: should take place the next day or as soon as possible, 
after the first day: clinical safety (See Appendix 2), INR, cardiac troponin I.

Schedule B:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers and viral vector shedding. Second day: must take place only when the results of the test for 
NAb to AAV9 are available. The time between the first and second day of the Screening Visit is expected to be between 3-4 weeks (based on the time to 
obtain the results of the NAb to AAV9 test). Only participants with a negative test for NAb to AAV9 will perform the rest of the Visit 1 assessments as per 
SoA. This includes the collection of blood and urine for: clinical safety tests (see Appendix 2), INR and cardiac troponin I. Participants with a positive test for 
NAb to AAV9 will be screen failed and will not attend the second day of Screening Visit (Visit 1).

Informed consent must be provided by the caregiver(s). The participant may also be required to provide assent in compliance with local regulations and institutional 
review board (IRB) requirements;

Screening blood tests with results considered by the Investigator to be transient and inconsistent with the participant’s clinical condition may be repeated once during the 
screening period for confirmation of eligibility;

Demographics: Information such as date of birth, race and ethnicity and gender will be collected in compliance with local regulations;
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 233
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Medical history will include results of genetic testing for confirmation of diagnosis of DMD. Results must confirm the presence of an abnormality (eg, deletion, 
duplication), or a point mutation in the dystrophin gene(s) which is consistent with the diagnosis of DMD. The mutation type will be reported. If the Investigator 
determines that the results are inconclusive, a repeat genetic testing will be allowed through the central laboratory at Screening (Visit 1) prior to any other assessments. 
In that case participants may return for the remainder of Screening (Visit 1) once results are confirmed (Section 8.7.1);

Medical history will also be reviewed for any significant medical history and concurrent illness(es) that required or are requiring specialist consultation or treatment;

Medication history: Complete medication history will include all prescription or nonprescription drugs, and dietary and herbal supplements taken within 30 days prior to 
the Screening Visit (Visit 1). The date the participant first started glucocorticoids for their DMD and the date of start of the background glucocorticoid regimen that the 
participant is taking at the time of Visit 1 (Screening Visit) must also be documented. In addition, the general immunization status including the immunization status 
against meningococcus, and any other vaccine(s) required by the eculizumab local prescribing information, must be documented;

Meningococcal vaccine: Participants who have no contraindications and who have not previously received a MenACWY vaccination; or whose last vaccination at the 
time of the Screening Visit (Visit 1) is outside the time period of active coverage specified by the vaccine manufacturer (Visit 1) must receive at least one dose of 
MenACWY vaccine as early as possible in the Screening Period and not later than 30 days before IP administration (see Section 6.5.1). Participants must also receive 
MenB vaccination if indicated by national vaccination guidelines. In addition, local eculizumab prescribing information, including additional vaccination and other 
requirements must also be followed (see Section 6.5.1).

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
b.
Visit 14 and Visit 19 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern 
and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood 
collection, may be performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory samples must be collected: 
Visit 14 (Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 234
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Visit 19 (Week 52)
First day: anti-HAV immunoglobulin M, Hepatitis B surface antigen, Hepatitis C antibody (these tests will not be applicable for Cohort 1 participants confirmed to 
meet exclusion criterion 15 [see Section 5.2]), NAb to AAV9, ADA to mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. 
Second day: clinical safety, INR, cardiac troponin I, biomarker (creatine kinase). 
c.
Visit 2 – Baseline Visit

Meningococcal vaccine: Only applicable for participants who have not received this vaccination at Screening (please refer to footnote a);

For sites outside the US, the Baseline visit should occur at least 31 calendar days prior to the planned IP administration visit, Day 1 (Visit 3), to allow for timely delivery 
of IP to the site, unless notified of earlier or later IP delivery by the study team. For US sites the Baseline visit should occur at least 16 calendar days prior to the planned 
IP administration visit, Day 1 (Visit 3), to allow for timely delivery of IP to the site, unless notified of earlier or later IP delivery by the study team; 

IP will be shipped to site following confirmation of participant’s eligibility (Section 5.1 and Section 5.2) and randomization. The amount of IP to be shipped to the site 
for IP administration at Visit 3 will be based on the measurement of body weight at the Baseline Visit (Visit 2). Body weight measurement must be verified by two site 
personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site.

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
d.
Visit 3 – Week 1, Day 1 (Day of IP administration)

Prior to IP administration, the Investigator must confirm applicable IP eligibility criteria (Section 6.1.1);

Participants will be instructed not to take their background glucocorticoid dose on Day 1 (Visit 3);

Participants are to be admitted to the site;

The following assessments must be performed prior to IP administration: physical examination, urine sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone 1 to 4 hours prior to infusion of IP; 

IP administration over approximately 2 to 4 hours (-15 minutes to +30 minutes including flush);
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 235
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved . Upon discharge, 
participants should stay near the site to enable prompt follow-up in the event of any emergent AEs through Day 14 (Visit 11), or longer if deemed necessary.
e.
Visits 12, 12.2, 13.2, 14.2 and 15

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
f.
Visit 18

This visit may be performed remotely (at or close to the participant’s home); in that case, it should include phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.

Amount of IP to be shipped to site for the IP administration on Day 390 (Visit 20) will be based on the measurement of body weight obtained at this visit. Body weight 
measurement must be verified by two site personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site. 
This visit is not applicable for Cohort 1 participants confirmed to meet exclusion criterion 15 (see Section 5.2).

For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be shipped to the site will be determined once the study has been 
restarted. Therefore, the weight collected at Day 328 (Visit 18) will not be entered into the interactive response technology drug management system during the dosing 
pause. Participants will be evaluated for Year 2 IP eligibility when the study is restarted.

May not be applicable for participants confirmed to meet exclusion criterion 15 or those who declined Year 2 IP administration (see Appendix 12 and Section 7.2.1).
g.
Early Discontinuation Visit

This visit is not applicable for participants who withdraw prior to Day 1 (Visit 3) or for Cohort 2 participants who are withdrawn from the study between Day 360 (Visit 
19) and Day 390 (Visit 20) (see Section 7.1).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 236
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only if the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
h.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable post-baseline unless safety concerns warrant full examination.
i.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
j.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
k.
12-Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
l.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 

For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 

On the following visits: Baseline Visit (Visit 2), Day 60 (Visit 14), Day 120 (Visit 16), Day 240 (Visit 17) and Day 360 (Visit 19), in which functional assessments 
(eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for 
additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
m.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
n.
Banked biospecimens for genetics are collected as described in Section 8.7.2.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 237
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
o.
Open muscle biopsies will be obtained in approximately the first 15 participants randomized into Cohorts 1 and 2, and their siblings, at sites that have been trained and 
certified by the Sponsor/Sponsor designee to collect open muscle biopsies, following administration of an anesthetic (eg, regional block or under general anesthesia) 
according to institutional standard practice, and only after any imaging and functional assessments scheduled for the same visit have been completed. Baseline visit muscle 
biopsies will be performed after randomization. If a muscle biopsy cannot be scheduled on the day of the Baseline visit, the biopsy may be performed at a later day, as long 
as it is at least 2 weeks before dosing.
p.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
q.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, ankle range of motion and FVC may be video recorded at the Day 1 
(Screening Visit), Baseline Visit (Visit 2), and at the annual visits (ie, Visits 19, 35, 37, 39, 41, 43). If CE re-training is required, the assigned master physiotherapist may 
request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be performed early in the course of the visit, to help reduce 
the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
r.
Ambulatory assessment at Screening (Visit 1) is based only on the ability to perform the 10 m run/walk, as assessed during the NSAA.
s.
An activity monitor will be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
t.
COAs will be completed by the caregiver on behalf of the participant and/or by the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
u.
Starting on Day 1 (Visit 3) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1).
v.
For eligibility for Year 1 IP administration please see Section 6.1.1.
w.
For details regarding post IP intensified safety monitoring please see Section 8.2.10. 
x.
A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo 2 post-Baseline muscle biopsies.  The post Baseline muscle biopsies will 
be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up. If the post-baseline muscle biopsy cannot be performed on the 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 238
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
scheduled day, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing for the biopsy at Visit 19 and within 1 month of the day of the visit for 
the biopsy at Visit 41.  
y.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
z.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) only after IP administration, as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a 
particular matrix (sample type) will be stopped when at least 2 consecutive negative results are observed in that matrix. See Section 8.8.5 for additional details.
aa.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data.  C3/C4 will also be sent to the central laboratory at Visits 6, 7, 8, 9, and 10. For more
details, please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 4 and 5, see Appendix 2 for details.
bb. In order to ensure an adequate understanding and management of potential safety risks, the initial rate of randomization into the study will be limited. No more than 2 
participants per week will be randomized at the start of the study, until 4 participants have been observed for at least 2 weeks post IP administration. After that, the rate could 
be increased to no more than 3 participants randomized per week (until at total of 10 participants have been observed for at least 2 weeks post-IP administration). Thereafter, 
the rate of randomization could be further increased to no more than 5 participants randomized per week (until a total of 20 participants have been observed for at least 2 
weeks post-IP administration). After this time, no limits of the randomization rate will be imposed unless the study team, in consultation with the E-DMC, determines 
otherwise. For more details- please see Section 4.1.
cc.
The NAb to AAV9 blood samples at the Baseline Visit (Visit 2) will always be collected and sent to the Central Laboratory, but will only be analyzed and reviewed prior to 
Day 1 Visit (Visit 3) if the time between the first blood draw for NAb to AAV9 testing at the Screening Visit (Visit 1) or most recent test, if repeat blood draw(s) was required, 
and the Day 1 Visit (Visit 3) is expected to be more than 55 days, which is anticipated to occur rarely. Dosing cannot occur unless there is a negative test to AAV9 from a 
sample collected 55 or less days before the day of IP administration.
dd. For US sites, only when approved by the relevant Institutional Review Board.
ee.
On Day 28 (Visit 12.2), only GLDH will be collected.
ff.
ADA to mini-dystrophin only.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 239
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1 
kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Wee
k 6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
gg. The Investigator will discuss with the participant and caregivers the importance of having a baseline cardiac MRI, even under general anesthesia, to be able to assess and 
manage potential cardiac adverse events during the study. This discussion and the decision to perform or not a baseline cardiac MRI will be documented in the participant’s 
records. A participant requiring anesthesia or unable to undergo investigation with closed MRI (eg, metal implants) may be exempt, and will be allowed to be randomized in 
the study without a cardiac MRI. Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration 
(Section 2.3.3.7). If the site considers gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast 
administration will be performed. It is important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may 
be required in certain situations (Section 8.2.8).
hh. Cardiac MRI may be performed at any time between the first day of the Screening Visit (Visit 1) and the Day 1 Visit (Visit 3), and after randomization, as long as it is done 
before Day 1 (Visit 3). If a prior cardiac MRI was performed within 6 months of the Screening Visit (with gadolinium, or without gadolinium if contrast administration is 
contraindicated), and results are available, then a cardiac MRI at screening will not be performed. Only participants with a pre-IP administration cardiac MRI will have a 
follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
ii.
Participants will be assessed by a cardiologist at the Screening Visit, see Section 5.2, exclusion criteria 16 and 17.
jj.
Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed 
necessary by the Investigator (see Section 8.2.10). 
kk. This visit is for sites in Germany only and only to test for cardiac troponin I. Unless clinical concern and/or participant preference and/or the site’s institutional review 
board’s preference warrants in-person visit, this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by 
local phlebotomist, as well as phone communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 240
10.14.2. Schedule of Activities – Year 2
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Eligibility for Year 2 IP 
administrationr
X
Hospital staydd
X




X
Physical examinationg
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationg
X
X
X
X
X
X
X
X
X
X
X
X
Height and Weight
X
X
X
X
X
X
X
Vital signs (supine BP, 
respiration, PR, body 
temp, and O2 
saturation)h,i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGj
X
X
X
X
X
X
CBCL
X
X
X
Xe
Laboratory Assessmentsk
Blood Samples
 NAb to AAV9
X
X
X
Xe
  ADA to mini-
dystrophin and AAV9
Xz
Xz
Xz
X
X
X
X
Xe
  ELISpot to mini-
dystrophin and AAV9
X
X
Xw
Xe
Viral Vector Sheddingu
X
X
X
X
X
X
Xe
Clinical safety 
(hematology, other)k
X
X
X
X
X
X
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 241
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Chemistry and hepatic 
safetyk
X
X
X
X
Xy
X
X
X
X
X
X
X
X
X
X
Post IP intensified safety 
monitoringk,s
X
X
X
X
X
Local and central 
laboratory testingx
X
X
X
X
X
X
X
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
X
Biomarker (creatine 
kinase) k
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked biospecimens for 
biomarkersl
X
X
Urine Samples
Clinical safety 
(urinalysis) k
X
X
X
X
X
X
X
X
X
X
Xe
Banked biospecimens for 
biomarkersl
X
X
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Saliva Samples
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Tissue Sample
Muscle Biopsy
Xff
Imaging Assessments
Echocardiogramm
X
X
Xe
Cardiac MRI aa
Xaa
Functional Assessments
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 242
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
FVCn t
X
X
Xe
NSAAn
X
X
X
X
X
X
X
Ankle range of motion 
X
X
X
X
X
X
X
Ambulatory status
X
X
X
X
X
X
X
Actigraphy o
X
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentp
X
X
X
X
X
EQ-5D-Y Proxyp
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGp
X
X
X
X
X
X
X
Participant-completed
Modified PODCI –
Adolescentp
X
X
X
EQ-5D-Yp
X
X
X
PGISp
X
X
X
Clinical evaluator-completed
CGISn
X
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
X
X
WPAI:DMD Caregiver
X
X
X
Study Interventions
Protocol-mandated 
glucocorticoid regimenq
X
X













X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 243
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Background 
glucocorticoid regimen
X



Xv
Xv
IP administration
X
Ongoing monitoring
Concomitant 
medications





















X
Serious and nonserious 
adverse event monitoring





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9= adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG = electrocardiogram; ELISpot= Enzyme-Linked ImmunoSpot; EQ-5D-Y= EuroQol 5 
Dimensions–Youth; FVC= Forced Vital Capacity; IP=investigational product; NAb=neutralizing antibodies; NSAA=North Star Ambulatory Assessment; PGIS= patient global 
impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; PR=pulse rate; temp=temperature.
a.
Visit 20 – Year 2, Week 1, Day 1

Prior to IP administration, the Investigator must confirm applicable Year 2 IP administration eligibility criteria (Section 7.1);

Participants are to be admitted to the site;

Participants will be instructed not to take their background glucocorticoid dose on Day 390 (Visit 20);

The following assessments must be performed prior to IP administration: Physical examination, blood collection (ELISpot to mini-dystrophin and AAV9), urine sample 
collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone approximately 1 to 4 hours prior to infusion of IP;

IP administration over approximately 2 to 4 hours (-15 minutes or +30 minutes including flush);
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 244
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site for at least 7 additional days to enable prompt follow-up in the event of any emergent AEs through Day 403 (Visit 28), or longer if 
deemed necessary.

If the time between the blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned Day 390 Visit (Visit 20) exceeds 13 weeks 
(90 days), due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), then the 
clinical safety laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP. The participant will not be withdrawn due to exceeding the time 
between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20), as described in Section 7.1.

If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), a participant’s Year 
2 IP administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be delayed for that participant until the pause is lifted. If the pause is not lifted 
within 6 months of the Day 360 (Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 ±7 days, and approximately every 6 months 
afterwards until the pause is lifted (or more frequently if considered necessary by the investigator) for sites in Israel, see Appendix 16  .
b.
Visits 29, 29.2, 30.2, 31.2, and 32

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
c.
Visit 31 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern and/or participant 
preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood collection, may be 
performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory assessments must be collected as follows: 
Visit 31 (Year 2, Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 245
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
d.
Visit 42 and 43 – Long-term follow up Year 6

All participants will be followed for 5 years after receiving fordadistrogene movaparvovec. Therefore Visits 42 and 43 only apply to participants randomized to Cohort 2.
e.
Early Discontinuation Visit

This visit is not applicable for Cohort 2 participants who were withdrawn from the study between Day 360 (Visit 19) and Day 390 (Visit 20) (see Section 7).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical Safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only If the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
f.
Visit Windows for Visits 20 through Visit 43

The number of days between each visit for Visit 20 (Year 2, IP administration) through Visit 43 must be maintained irrespective of the actual visit day of Visit 20, eg, if 
the actual visit day at Visit 20 is 392 (instead of 390), then Visit 21 will take place on Day 393 (instead of Day 391), etc. 
g.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable unless safety concerns warrant full examination.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 246
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
h.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
i.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
j.
12 Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
k.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 
For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 
If the time between the blood draw for the clinical safety laboratory tests on Visit 19 (Day 360) and the planned Visit 20 (Day 390) exceeds 13 weeks (90 days due to 
operational or administrative reasons [eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays]), then the clinical safety 
laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP, but the participant will not be withdrawn due to exceeding the time between Visit 
19 (Day 360) and the planned Visit 20 (Day 390), as described in Section 7.1.
l.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
m.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation.
n.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, range of motion and FVC may be video recorded at the annual visits. If 
CE re-training is required, the assigned master physiotherapist may request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments 
should be performed early in the course of the visit, to help reduce the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of 
assessments please consult the Functional Assessment Manual. On the following visits: Day 449 (Visit 31), Day 509 (Visit 33), Day 629 (Visit 34) and Day 749 (Visit 35), in 
which functional assessments (eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the 
functional test; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
o.
An activity monitor may be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 247
Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
p.
COAs will be completed by the caregiver on behalf of the participant and/or the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
q.
Starting on Day 390 (Visit 20) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1). If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety 
review, operational issues causing significant delays), participants must delay Year 2 IP administration, they will not receive the protocol-mandated glucocorticoid regimen 
until the pause is lifted and Year 2 IP administration takes place; they will remain on their background glucocorticoid regimen until then.
r.
For eligibility for Year 2 IP administration please see Section 7.1.
s.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
t.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
u.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a particular matrix (sample type) will 
be stopped when at least 2 consecutive negative results are observed in that matrix.
v.
After two years (Day 749), any change to the background glucocorticoid regimen will be permitted (see Section 6.5.1).
w.
ELISpot to mini-dystrophin and AAV9 if a clinical event has occurred that, in the opinion of the Sponsor and/or the Investigator, could be due to an immunological reaction. 
If ELISpot is to be collected, these visits should be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. The 
following laboratory assessments must be collected as follows:
First day: NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase).
x.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 26 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data. C3/C4 will also be sent to the central laboratory at Visits 23, 24, 25, 26 and 27. For 
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PFIZER CONFIDENTIAL
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Period
Year 2
Long-term follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 
20a,bb,
cc
Visit 
21bb,
cc
Visit 
22bb, cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,
cc & 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30,bb,
cc
Visit 
30.1ee,
bb, cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 36, 
38, 40, 
42d
Visits 37, 
39, 41, 43d
Year 
2, 
Week 
1, 
Day 1
Year 
2, 
Week 
1, 
Day 
2
Year 2, 
Week 
1, Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 3, 
4, 5, 6d
Years 3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
more details please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 21 and 22, see Appendix 2 for 
details.
y.
On Day 417 (Visit 29.2), only GLDH will be collected.
z.
ADA to mini-dystrophin only.
aa.
Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration (Section 2.3.3.7). If the site considers 
gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast administration will be performed. It is 
important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may be required in certain situations 
(Section 8.2.8). Only participants with a pre-IP administration cardiac MRI will have a follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35). 
bb. Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not attend Visits 20 to 30.2 and therefore will not 
perform the corresponding tests and assessments. These participants will not receive their protocol-mandated glucocorticoid regimen at Year 2. For details on the 
retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
cc.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not receive their protocol-mandated glucocorticoid 
regimen at Year 2. For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
dd. Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
ee.
This visit is for sites in Germany only and only to test for cardiac troponin I. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s 
preference warrants in-person visit, this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local 
phlebotomist, as well as phone communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ff.    A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo two post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-Baseline muscle biopsy cannot be scheduled on the 
day of Visit 19 or Visit 41, it may be performed at a later date, as long as it is at least 2 weeks before dosing, for the biopsy at Visit 19 and within 1 month of the day of the 
visit for the biopsy at Visit 41.
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10.14.3. Inclusion Criteria
Participants are eligible to be included in the study only if all of the following criteria apply:
1.
Male participants who are ≥4 and <8 years of age at Screening (Visit 1).
2.
Confirmed diagnosis of DMD by prior genetic testing demonstrating the presence of a 
mutation in the dystrophin gene consistent with DMD at Screening (Visit 1). If the 
Investigator determines that the results are inconclusive, a repeat genetic testing will be 
allowed through the central laboratory at Screening (Visit 1).
3.
Receipt of a stable daily dose of glucocorticoids (≥0.5 mg/kg/day prednisone, 
prednisolone, or ≥0.75 mg/kg/day deflazacort) for at least 3 months prior to Screening (Visit 
1) and during the period between Screening (Visit 1) and Day 1 (Visit 3). In order to comply 
with protocol procedures, there should also be a reasonable expectation that this daily dose of 
glucocorticoids will remain stable for the first 2 years of the study. A stable dose is defined 
as one in which any change is ≤0.2 mg/kg (See Section 6.5.1 for detailed requirements).
4.
A NSAA total score >16 and <30 at Screening (Visit 1).
5.
Ambulatory, defined as being able to walk 10 meters unassisted, at Screening (Visit 
1).
6.
Participants/legally acceptable representatives who are willing and able to comply 
with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other 
study procedures including, potentially, open muscle biopsies under general anesthesia and 
cardiac MRI under general anesthesia.
7.
Participants/legally acceptable representatives who are capable of giving 
assent/signed informed consent as described in Appendix 1, which includes compliance with 
the requirements and restrictions listed in the assent/informed consent document (ICD) and in 
this protocol.
8.
Participants/legally acceptable representatives who are willing to protect the integrity 
of the study data by not actively seeking sensitive clinical data (eg, CK, ALT, AST, NAb to 
AAV9) through independent laboratory tests and by not sharing trial experiences with other 
participants or publicly (eg, through social media).
9.
For sites in Germany only: At the Screening Visit (Visit 1), the investigator will 
discuss and agree with the participant or their legally acceptable representative the potential 
need for an autopsy, if the participant dies between Year 1 IP administration and during the 
following 10 years.
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PFIZER CONFIDENTIAL
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10.14.4. Exclusion Criteria
Participants are excluded from the study if any of the following criteria apply:
1. Prior treatment with gene therapy, defined as any therapy introducing exogenous 
DNA or intended to permanently alter the endogenous DNA. Gene therapy (other 
than IP) will be prohibited for the duration of the study.
2. Exposure within 6 months prior to Screening (Visit 1) to any treatment designed 
to increase dystrophin expression (including, but not limited to exon-skipping and 
nonsense read-through). These treatments will also be prohibited during the 
period between Screening (Visit 1) and Day 1 (Visit 3) and for the first 52 weeks 
of the study. Please note that for participants who are eligible for these treatments:
Participants may be enrolled who have previously experienced lack of efficacy, or 
intolerance, as long as they received their last dose more than 6 months before 
screening (Visit 1), or who have refused these treatments.
Participants receiving these treatments from which there is believed to be benefit 
should not discontinue them in order to meet this exclusion criterion and 
enroll in the study.
3. Previous administration with an investigational drug or investigational vaccine 
within 30 days (or as determined by the local requirement) or 5 half-lives 
(whichever is longer) at Screening (Visit 1). These treatments will also be 
prohibited during the period between Screening (Visit 1) and Day 1 (Visit 3) and 
for the first 2 years of the study.
4. Known cognitive impairment or behavioral issues that would impede the ability to 
follow instructions, in the judgment of the Investigator, at Screening (Visit 1).
5. Any nonhealed injury at Screening (Visit 1) which, in the opinion of the 
Investigator, may impact functional testing; additionally, lower limb fractures 
must have been healed for at least 3 months prior to Screening (Visit 1).
6. Positive test for NAb to AAV9, based on the threshold determined by the Central 
Laboratory, from a sample taken at Screening (Visit 1). 
7. Receipt of a live attenuated vaccination within 30 days prior to Screening 
(Visit 1). Receipt of a live attenuated vaccination will also be prohibited for 90 
days before Day 1 (Visit 3), for 90 days prior to Year 2 IP administration, and for 
the first 2 months after each IP administration.
8. Abnormality in hematology or chemistry profiles at Screening (Visit 1). A single 
repeat for value(s) outside allowable limits is permitted to re-assess eligibility: 
a.
Absolute neutrophil count <1000 cells/mm3;
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b. Platelets <150 x 103/µl;
c.
Cystatin C >1.2 x ULN;
d. Positive hepatitis A virus (anti-HAV) immunoglobulin M, hepatitis B surface 
antigen (HbsAg), and/or hepatitis C antibody (HCVAb);
e.
Markers of hepatic inflammation or overt or occult cirrhosis as evidenced by 
one or more of the following:
1. Prothrombin time (PT) > upper limit of normal (ULN); prolonged 
international normalized ratio (INR) >ULN;
2. GLDH >2 x ULN;
3. Total bilirubin >1.5 x ULN (unless the participant has a history of Gilbert 
disease) and direct bilirubin >0.5 mg/dL;
4. Gamma-glutamyl transferase (GGT) >1.5 x ULN.
9. Other acute or chronic medical or psychiatric condition at Screening (Visit 1), 
including recent (within the past year) or active suicidal ideation or behavior 
(using screening by the Child Behavior Check List (CBCL) and determined by the 
Investigator, as described in Section 8.2.13) or laboratory abnormality that may 
increase the risk associated with study participation or IP administration or may 
interfere with the interpretation of study results and, in the judgment of the 
Investigator, would make the participant inappropriate for entry into this study.
10. Acute infection at Screening (Visit 1) or Baseline (Visit 2) that, in the judgement 
of the Investigator is not expected to be fully resolved at least 2 weeks before 
Day 1 (Visit 3). At Day 1 (Visit 3), participants must have been infection-free for 
at least 2 weeks prior to IP administration. Delay of IP administration for up to 14 
days is permitted to enable infections to become fully resolved. 
11. Investigator site staff members directly involved in the conduct of the study and 
their family members, site staff members otherwise supervised by the 
Investigator, or Pfizer employees, including their family members, directly 
involved in the conduct of the study. 
12. Known hypersensitivity to any of the components of the IP or solution for 
infusion, such as hypersensitivity to albumin or a diagnosis of HFI. Symptoms 
suggestive of HFI include nausea, vomiting, bloating, stomach cramps, or 
diarrhea following the ingestion of sweet foods or drinks, or a pattern of avoiding 
sweet foods or drinks.
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PFIZER CONFIDENTIAL
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13. Contraindication to the use of eculizumab, as per the local prescribing 
information.
14. LVEF <50% on echocardiogram performed at the Screening Visit (Visit 1), as 
evaluated by the central reader.
15. Participants with the following genetic abnormalities in the dystrophin gene as 
confirmed by the investigator based on the review of DMD genetic testing:
a.
Any mutation (exon deletion, exon duplication, insertion, or point mutation) 
affecting any exon between exon 9 and exon 13, inclusive; OR
b. A deletion that affects both exon 29 and exon 30;OR
c.
A deletion that affects any exons between 56-71, inclusive.
For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12.
16. Cardiac pathologies, as evaluated by a pediatric cardiologist at the Screening Visit 
(Visit 1):
a.
Diagnosis of myocarditis (eg, viral): either based on prior medical history or 
based on findings in cardiac imaging tests;
b. Any other cardiac history, and/or condition and/or abnormalities in cardiac 
imaging, that determine that the participant should not be included in the 
study, as per the cardiologist.
17. Not a candidate for mechanical cardiac or respiratory support, or any other 
invasive intervention, if indicated for management of an acute event as 
determined by the cardiologist in consultation with the investigator at the 
Screening Visit (Visit 1). 
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PFIZER CONFIDENTIAL
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10.15. Appendix 15: Russia Appendix
10.15.1. Schedule of Activities – Year 1 
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Informed 
consent/assent
X
Inform caregivers 
about study 
C3391007dd
X
Demography
X
Medical history
Xii
Medication 
history
X
Review of 
inclusion/exclusio
n criteria
X
X
Eligibility for 
Year 1 IP 
administrationv
X
Hospital stayjj
X




X
Physical 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
Weight
X
X
X
X
X
X
X
Height
X
X
X
X
X
X
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Vital signs 
(supine BP, 
respiratory rate, 
PR, body temp, 
and O2 
saturation)i,j
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGk
X
X
X
X
X
X
CBCL
X
X
X
g
Randomization
Xbb
Laboratory Assessmentsl
Blood Samples
NAb
X
(X)cc
X
X
X
g
ADA to 
mini-dystrophi
n and AAV9
X
Xff
Xff
Xff
X
X
X
X
g
ELISpot to 
mini-
dystrophin and 
AAV9
X
X
X
g
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
g
Clinical safety 
(hematology, 
other)l
X
X
X
X
X
X
X
X
X
X
X
X
g
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CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
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Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Chemistry and 
hepatic safety l
X
X
X
X
X
Xee
X
X
X
X
X
X
X
X
X
Post IP intensified 
safety monitoring,l
w
X
X
X
X
X
Local and central 
laboratory 
testingaa
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Cardiac Troponin 
I
X
X
X
X
X
X
X
X
X
X
X
X
International 
normalized ratio 
(INR),
Hepatitis A virus 
(anti-HAV) 
immunoglobulin
M 
Hepatitis B 
surface antigen,
Hepatitis C 
antibodyl
X
X
Biomarker 
(creatine kinase)l
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked 
biospecimens for 
biomarkersm
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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PFIZER CONFIDENTIAL
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Page 256
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Banked 
biospecimens for 
geneticsn
X
Urine Samples
Clinical safety 
(urinalysis)l
X
X
X
X
X
X
X
X
X
X
g
Banked 
biospecimens for 
biomarkersm
X
X
X
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Saliva Samples
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Tissue Samples
Muscle biopsyo
X
Xx
Imaging 
Assessments
Echocardiogramp
X
X
X
g
Cardiac MRIgg
Xhh
Xhh
Functional Assessments
FVCq,y
X
X
X
g
NSAAq
X
X
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 257
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Ankle range of 
motion 
X
X
X
X
X
X
X
Ambulatory status
Xr
X
X
X
X
X
Actigraphys
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI 
– Pediatric Parentt
X
X
X
X
EQ-5D-Y Proxyt
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGt
X
X
X
X
X
X
Participant-completed
EQ-5D-Yt
X
X
Clinical evaluator-completed
CGISq
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
WPAI:DMD 
Caregiver
X
Interventions
Protocol-
mandated 
glucocorticoid 
regimenu
X
X













X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 258
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Background 
glucocorticoid 
regimen
X
X
X




IP administration
X
Meningococcal 
vaccine
X
X
Ongoing 
monitoring
Concomitant 
medications
X





















X
Serious and 
nonserious 
adverse event 
monitoring 
X





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9=adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG=electrocardiogram; ELISpot=Enzyme-Linked ImmunoSpot; EQ-5D-Y=EuroQol 5 
Dimensions–Youth; FVC=Forced Vital Capacity; IP=investigational product; Men ACWY=Meningococcal serogroups A, C, W, and Y; NAb=neutralizing antibodies; 
NSAA=North Star Ambulatory Assessment; PGIS=patient global impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; temp=temperature; PR=pulse 
rate. Schedule of Activities – Year 2 and Long-Term Follow Up
a.
Visit 1 – Screening Visit 

During screening, participants and caregiver(s) will be assessed for study eligibility in accordance with the Inclusion/Exclusion Criteria as described in Section 5.1 and 
Section 5.2; 

Visit 1 must be conducted over the course of 2 days. The investigator will decide which of the schedules below they will follow and inform the study team:

Schedule A:
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 259
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. Second day: should take place the next day or as soon as possible, 
after the first day: clinical safety (See Appendix 2), INR, cardiac troponin I.

Schedule B:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers and viral vector shedding. Second day: must take place only when the results of the test for 
NAb to AAV9 are available. The time between the first and second day of the Screening Visit is expected to be between 3-4 weeks (based on the time to 
obtain the results of the NAb to AAV9 test). Only participants with a negative test for NAb to AAV9 will perform the rest of the Visit 1 assessments as per 
SoA. This includes the collection of blood and urine for: clinical safety tests (see Appendix 2), INR and cardiac troponin I. Participants with a positive test for 
NAb to AAV9 will be screen failed and will not attend the second day of Screening Visit (Visit 1).

Informed consent must be provided by the caregiver(s). The participant may also be required to provide assent in compliance with local regulations and institutional 
review board (IRB) requirements;

Screening blood tests with results considered by the Investigator to be transient and inconsistent with the participant’s clinical condition may be repeated once during the 
screening period for confirmation of eligibility;

Demographics: Information such as date of birth, race and ethnicity and gender will be collected in compliance with local regulations;

Medical history will include results of genetic testing for confirmation of diagnosis of DMD. Results must confirm the presence of an abnormality (eg, deletion, 
duplication), or a point mutation in the dystrophin gene(s) which is consistent with the diagnosis of DMD. The mutation type will be reported. If the Investigator 
determines that the results are inconclusive, a repeat genetic testing will be allowed through the central laboratory at Screening (Visit 1) prior to any other assessments. 
In that case participants may return for the remainder of Screening (Visit 1) once results are confirmed (Section 8.7.1);

Medical history will also be reviewed for any significant medical history and concurrent illness(es) that required or are requiring specialist consultation or treatment;

Medication history: Complete medication history will include all prescription or nonprescription drugs, and dietary and herbal supplements taken within 30 days prior to 
the Screening Visit (Visit 1). The date the participant first started glucocorticoids for their DMD and the date of start of the background glucocorticoid regimen that the 
participant is taking at the time of Visit 1 (Screening Visit) must also be documented. In addition, the general immunization status including the immunization status 
against meningococcus, and any other vaccine(s) required by the eculizumab local prescribing information, must be documented;
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 260
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Meningococcal vaccine: Participants who have no contraindications and who have not previously received a MenACWY vaccination; or whose last vaccination at the 
time of the Screening Visit (Visit 1) is outside the time period of active coverage specified by the vaccine manufacturer (Visit 1) must receive at least one dose of 
MenACWY vaccine as early as possible in the Screening Period and not later than 30 days before IP administration (see Section 6.5.1). Participants must also receive 
MenB vaccination if indicated by national vaccination guidelines. In addition, local eculizumab prescribing information, including additional vaccination and other 
requirements must also be followed (see Section 6.5.1).

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
b.
Visit 14 and Visit 19 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern 
and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood 
collection, may be performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory samples must be collected: 
Visit 14 (Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
Visit 19 (Week 52)
First day: anti-HAV immunoglobulin M, Hepatitis B surface antigen, Hepatitis C antibody (these tests will not be applicable for Cohort 1 participants confirmed to 
meet exclusion criterion 15 [see Section 5.2]), NAb to AAV9, ADA to mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. 
Second day: clinical safety, INR, cardiac troponin I, biomarker (creatine kinase). 
c.
Visit 2 – Baseline Visit

Meningococcal vaccine: Only applicable for participants who have not received this vaccination at Screening (please refer to footnote a);
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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PFIZER CONFIDENTIAL
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Page 261
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

For sites outside the US, the Baseline visit should occur at least 31 calendar days prior to the planned IP administration visit, Day 1 (Visit 3), to allow for timely delivery 
of IP to the site, unless notified of earlier or later IP delivery by the study team. For US sites the Baseline visit should occur at least 16 calendar days prior to the planned 
IP administration visit, Day 1 (Visit 3), to allow for timely delivery of IP to the site, unless notified of earlier or later IP delivery by the study team; 

IP will be shipped to site following confirmation of participant’s eligibility (Section 5.1 and Section 5.2) and randomization. The amount of IP to be shipped to the site 
for IP administration at Visit 3 will be based on the measurement of body weight at the Baseline Visit (Visit 2). Body weight measurement must be verified by two site 
personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site.

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
d.
Visit 3 – Week 1, Day 1 (Day of IP administration)

Prior to IP administration, the Investigator must confirm applicable IP eligibility criteria (Section 6.1.1);

Participants will be instructed not to take their background glucocorticoid dose on Day 1 (Visit 3);

Participants are to be admitted to the site;

The following assessments must be performed prior to IP administration: physical examination, urine sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone 1 to 4 hours prior to infusion of IP; 

IP administration over approximately 2 to 4 hours (-15 minutes to +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site to enable prompt follow-up in the event of any emergent AEs through Day 14 (Visit 11), or longer if deemed necessary.
e.
Visits 12, 12.2, 13.2, 14.2 and 15
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Page 262
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
f.
Visit 18

This visit may be performed remotely (at or close to the participant’s home); in that case, it should include phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.

Amount of IP to be shipped to site for the IP administration on Day 390 (Visit 20) will be based on the measurement of body weight obtained at this visit. Body weight 
measurement must be verified by two site personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site. 
This visit is not applicable for Cohort 1 participants confirmed to meet exclusion criterion 15 (see Section 5.2).

For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be shipped to the site will be determined once the study has been 
restarted. Therefore, the weight collected at Day 328 (Visit 18) will not be entered into the interactive response technology drug management system during the dosing 
pause. Participants will be evaluated for Year 2 IP eligibility when the study is restarted.

May not be applicable for participants confirmed to meet exclusion criterion 15 or those who declined Year 2 IP administration (see Appendix 12 and Section 7.2.1).
g.
Early Discontinuation Visit

This visit is not applicable for participants who withdraw prior to Day 1 (Visit 3) or for Cohort 2 participants who are withdrawn from the study between Day 360 (Visit 
19) and Day 390 (Visit 20) (see Section 7.1).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 263
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only if the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
h.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable post-baseline unless safety concerns warrant full examination.
i.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
j.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
k.
12-Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
l.
Clinical laboratory tests are described in detail in Table 5 (Appendix 15). 

For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 

On the following visits: Baseline Visit (Visit 2), Day 60 (Visit 14), Day 120 (Visit 16), Day 240 (Visit 17) and Day 360 (Visit 19), in which functional assessments 
(eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for 
additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
m.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
n.
Banked biospecimens for genetics are collected as described in Section 8.7.2.
o.
Open muscle biopsies will be obtained in approximately the first 15 participants randomized into Cohorts 1 and 2, and their siblings (with the potential to collect a 
maximum of 33 if needed), at sites that have been trained and certified by the Sponsor/Sponsor designee to collect open muscle biopsies, following administration of an 
anesthetic (eg, regional block or under general anesthesia) according to institutional standard practice, and only after any imaging and functional assessments scheduled for 
the same visit have been completed.  Baseline Visit muscle biopsies will be performed after randomization. If a muscle biopsy cannot be scheduled on the day of the 
Baseline Visit, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 264
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
p.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
q.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, ankle range of motion and FVC may be video recorded at the Day 1 
(Screening Visit), Baseline Visit (Visit 2), and at the annual visits (ie, Visits 19, 35, 37, 39, 41, 43). If CE re-training is required, the assigned master physiotherapist may 
request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be performed early in the course of the visit, to help reduce 
the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
r.
Ambulatory assessment at Screening (Visit 1) is based only on the ability to perform the 10 m run/walk, as assessed during the NSAA.
s.
An activity monitor will be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
t.
COAs will be completed by the caregiver on behalf of the participant and/or by the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
u.
Starting on Day 1 (Visit 3) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1).
v.
For eligibility for Year 1 IP administration please see Section 6.1.1.
w.
For details regarding post IP intensified safety monitoring please see Section 8.2.10. 
x.
All participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo 2 post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-baseline muscle biopsy cannot be performed on the 
scheduled day, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing for the biopsy at Visit 19 and within 1 month of the day of the visit for 
the biopsy at Visit 41.
y.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 265
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
z.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) only after IP administration, as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a 
particular matrix (sample type) will be stopped when at least 2 consecutive negative results are observed in that matrix. See Section 8.8.5 for additional details.
aa.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 9 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data.  C3/C4 will also be sent to the central laboratory at Visits 6, 7, 8, 9, and 10.  For 
more details, please see Section 8.2.12 and Section 10.15.1. 
bb. In order to ensure an adequate understanding and management of potential safety risks, the initial rate of randomization into the study will be limited. No more than 2 
participants per week will be randomized at the start of the study, until 4 participants have been observed for at least 2 weeks post IP administration. After that, the rate could 
be increased to no more than 3 participants randomized per week (until at total of 10 participants have been observed for at least 2 weeks post-IP administration). Thereafter, 
the rate of randomization could be further increased to no more than 5 participants randomized per week (until a total of 20 participants have been observed for at least 2 
weeks post-IP administration). After this time, no limits of the randomization rate will be imposed unless the study team, in consultation with the E-DMC, determines 
otherwise. For more details- please see Section 4.1.
cc.
The NAb to AAV9 blood samples at the Baseline Visit (Visit 2) will always be collected and sent to the Central Laboratory, but will only be analyzed and reviewed prior to 
Day 1 Visit (Visit 3) if the time between the first blood draw for NAb to AAV9 testing at the Screening Visit (Visit 1) or most recent test, if repeat blood draw(s) was required, 
and the Day 1 Visit (Visit 3) is expected to be more than 55 days, which is anticipated to occur rarely. Dosing cannot occur unless there is a negative test to AAV9 from a 
sample collected 55 or less days before the day of IP administration.
dd. For US sites, only when approved by the relevant Institutional Review Board.
ee.
On Day 28 (Visit 12.2), only GLDH will be collected.
ff.
ADA to mini-dystrophin only.
gg. Investigators will discuss with the participant and/or their caregiver the importance of having a baseline cardiac MRI, even under general anesthesia, to be able to assess and 
manage potential cardiac adverse events during the study. This discussion and the decision to perform or not a baseline cardiac MRI will be documented in the participant's 
records. A participant requiring anesthesia or unable to undergo investigation with closed MRI (eg, metal implants) may be exempt, and will be allowed to be randomized in 
the study without a cardiac MRI. Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration 
(Section 2.3.3.7). If the site considers gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 266
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
administration will be performed. It is important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may 
be required in certain situations (Section 8.2.8).
hh. Cardiac MRI may be performed at any time between the first day of the Screening Visit (Visit 1) and the Day 1 Visit (Visit 3), and after randomization, as long as it is done 
before Day 1 (Visit 3). If a prior cardiac MRI was performed within 6 months of the Screening Visit (with gadolinium, or without gadolinium if contrast administration is 
contraindicated), and results are available, then a cardiac MRI at screening will not be performed. Only participants with a pre-IP administration cardiac MRI will have a 
follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
ii.
Participants will be assessed by a cardiologist at the Screening Visit, see Section 5.2, exclusion criteria 16 and 17.
jj.
Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed 
necessary by the Investigator (see Section 8.2.10). 
kk. This visit is for sites in Germany only. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, 
this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone 
communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 267
10.15.2. Schedule of Activities – Year 2 and Long Term Follow Up
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Eligibility for Year 2 IP 
administrationr
X
Hospital staydd
X




X
Physical examinationg
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological examinationg
X
X
X
X
X
X
X
X
X
X
X
X
Height and Weight
X
X
X
X
X
X
X
Vital signs (supine BP, 
respiration, PR, body 
temp, and O2 saturation)h,i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGj
X
X
X
X
X
X
CBCL
X
X
X
Xe
Laboratory Assessmentsk
Blood Samples
 NAb to AAV9
X
X
X
Xe
ADA to mini-dystrophin 
and AAV9
Xz
Xz
Xz
X
X
X
X
Xe
  ELISpot to mini-
dystrophin and AAV9
X
X
Xw
Xe
Viral Vector Sheddingu
X
X
X
X
X
X
Xe
Clinical safety 
(hematology, other) k
X
X
X
X
X
X
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 268
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Chemistry and hepatic 
safetyk
X
X
X
X
Xy
X
X
X
X
X
X
X
X
X
X
Post IP intensified safety 
monitoringk,s
X
X
X
X
X
Local and central 
laboratory testingx
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
X
Biomarker (creatine 
kinase)k
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked biospecimens for 
biomarkersl
X
X
Urine Samples
Clinical safety 
(urinalysis)k
X
X
X
X
X
X
X
X
X
X
Xe
Banked biospecimens for 
biomarkersl
X
X
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Saliva Samples
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Tissue Sample
Muscle Biopsy
Xff
Imaging Assessments
Echocardiogramm
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 269
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Cardiac MRIaa
Xaa
Functional Assessments
FVCn,t
X
X
Xe
NSAAn
X
X
X
X
X
X
X
Ankle range of motion 
X
X
X
X
X
X
X
Ambulatory status
X
X
X
X
X
X
X
Actigraphyo
X
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentp
X
X
X
X
X
EQ-5D-Y Proxyp
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGp
X
X
X
X
X
X
X
Participant-completed
Modified PODCI –
Adolescentp
X
X
X
EQ-5D-Yp
X
X
X
PGISp
X
X
X
Clinical evaluator-completed
CGISn
X
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 270
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
WPAI:DMD Caregiver
X
X
X
Study Interventions
Protocol-mandated 
glucocorticoid regimenq
X
X













X
Background 
glucocorticoid regimen
X



Xv
Xv
IP administration
X
Ongoing monitoring
Concomitant medications





















X
Serious and nonserious 
adverse event monitoring





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9= adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG = electrocardiogram; ELISpot= Enzyme-Linked ImmunoSpot; EQ-5D-Y= EuroQol 5 
Dimensions–Youth; FVC= Forced Vital Capacity; IP=investigational product; NAb=neutralizing antibodies; NSAA=North Star Ambulatory Assessment; PGIS= patient global 
impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; PR=pulse rate; temp=temperature.
a.
Visit 20 – Year 2, Week 1, Day 1

Prior to IP administration, the Investigator must confirm applicable Year 2 IP administration eligibility criteria (Section 7.1);

Participants are to be admitted to the site;

Participants will be instructed not to take their background glucocorticoid dose on Day 390 (Visit 20);

The following assessments must be performed prior to IP administration: Physical examination, blood collection (ELISpot to mini-dystrophin and AAV9), urine sample 
collection, ECG and vital signs; 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 271
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone approximately 1 to 4 hours prior to infusion of IP;

IP administration over approximately 2 to 4 hours (-15 minutes or +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital stay. 
Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed necessary by the Investigator 
(see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, participants 
should stay near the site for at least 7 additional days to enable prompt follow-up in the event of any emergent AEs through Day 403 (Visit 28), or longer if deemed 
necessary.

If the time between the blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned Day 390 Visit (Visit 20) exceeds 13 weeks (90 days), 
due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), then the clinical safety 
laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP. The participant will not be withdrawn due to exceeding the time between Day 360 
Visit (Visit 19) and Day 390 Visit (Visit 20), as described in Section 7.1.

If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), a participant’s Year 2 
IP administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be delayed for that participant until the pause is lifted. If the pause is not lifted 
within 6 months of the Day 360 (Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 ±7 days, and approximately every 6 months 
afterwards until the pause is lifted (or more frequently if considered necessary by the investigator) for sites in Israel, see Appendix 16 .
b.
Visits 29, 29.2, 30.2, 31.2, and 32

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed remotely, 
and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 272
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
c.
Visit 31 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern and/or participant 
preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood collection, may be 
performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory assessments must be collected as follows: 
Visit 31 (Year 2, Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
d.
Visit 42 and 43 – Long-term follow up Year 6

All participants will be followed for 5 years after receiving fordadistrogene movaparvovec. Therefore Visits 42 and 43 only apply to participants randomized to Cohort 2.
e.
Early Discontinuation Visit

This visit is not applicable for Cohort 2 participants who were withdrawn from the study between Day 360 (Visit 19) and Day 390 (Visit 20) (see Section 7).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 1110).

Clinical Safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only If the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early Discontinuation 
Visit.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 273
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
f.
Visit Windows for Visits 20 through Visit 43

The number of days between each visit for Visit 20 (Year 2, IP administration) through Visit 43 must be maintained irrespective of the actual visit day of Visit 20, eg, if the 
actual visit day at Visit 20 is 392 (instead of 390), then Visit 21 will take place on Day 393 (instead of Day 391), etc. 
g.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable unless safety concerns warrant full examination.
h.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
i.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
j.
12 Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized interpretation. 
k.
Clinical laboratory tests are described in detail in in Table 5 (Section 10.15.1). 
For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 
If the time between the blood draw for the clinical safety laboratory tests on Visit 19 (Day 360) and the planned Visit 20 (Day 390) exceeds 13 weeks (90 days due to 
operational or administrative reasons [eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays]), then the clinical safety laboratory 
tests should be repeated and eligibility (re)confirmed prior to administering IP, but the participant will not be withdrawn due to exceeding the time between Visit 19 (Day 360) 
and the planned Visit 20 (Day 390), as described in Section 7.1.
l.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
m.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation.
n.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments (NSAA, 
ankle range of motion and FVC) for the same participant throughout the study. The NSAA, range of motion and FVC may be video recorded at the annual visits. If CE re-
training is required, the assigned master physiotherapist may request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be 
performed early in the course of the visit, to help reduce the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 274
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
consult the Functional Assessment Manual. On the following visits: Day 449 (Visit 31), Day 509 (Visit 33), Day 629 (Visit 34) and Day 749 (Visit 35), in which functional 
assessments (eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for 
additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
o.
An activity monitor may be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 weeks.
p.
COAs will be completed by the caregiver on behalf of the participant and/or the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
q.
Starting on Day 390 (Visit 20) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants may 
return to their background glucocorticoid regimen (see Section 6.5.1). If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, 
operational issues causing significant delays), participants must delay Year 2 IP administration, they will not receive the protocol-mandated glucocorticoid regimen until the 
pause is lifted and Year 2 IP administration takes place; they will remain on their background glucocorticoid regimen until then.
r.
For eligibility for Year 2 IP administration please see Section 7.1.
s.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
t.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC evaluated 
at any time during the study.
u.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a particular matrix (sample type) will be 
stopped when at least 2 consecutive negative results are observed in that matrix.
v.
After two years (Day 749), any change to the background glucocorticoid regimen will be permitted (see Section 6.5.1).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 275
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
w.
ELISpot to mini-dystrophin and AAV9 if a clinical event has occurred that, in the opinion of the Sponsor and/or the Investigator, could be due to an immunological reaction. If 
ELISpot is to be collected, these visits should be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. The following 
laboratory assessments must be collected as follows:
First day: NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase).
x.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 26 will be sent to the
central laboratory to prevent sharing the results of ALT/AST sensitive clinical data. C3/C4 will also be sent to the central laboratory at Visits 23, 24, 25, 26 and 27. For more 
details please see Section 8.2.12 and Appendix 15.
y.
On Day 417 (Visit 29.2), only GLDH will be collected.
z.
ADA to mini-dystrophin only.
aa.
Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration (Section 2.3.3.7). If the site considers 
gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast administration will be performed. It is 
important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may be required in certain situations 
(Section 8.2.8). Only participants with a pre-IP administration cardiac MRI will have a follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35). 
bb. Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not attend Visits 20 to 30.2 and therefore will not 
perform the corresponding tests and assessments. These participants will not receive their protocol-mandated glucocorticoid regimen at Year 2. For details on the retrospective 
assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
cc.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not receive their protocol-mandated glucocorticoid 
regimen at Year 2. For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
dd. Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 276
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb,cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb,
cc
Visit 
25bb,cc
&26
bb, cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,bb,
cc
Visit 
29.2b,
bb, cc
Visit 
30bb,
cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b,
bb, cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 33 Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Wee
k 1, 
Day 
2
Year 
2, 
Wee
k 1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, 
Day 
7
Year 
2, 
Week 
2, 
Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 
2, 
Week 
7
Year 2, 
Week 9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 2, 
Week 
18
Year 
2, 
Week 
35
Year 2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396 397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
ee.
This visit is for sites in Germany only. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this 
visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication 
between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ff.
A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo two post-Baseline muscle biopsies.  The post Baseline muscle biopsies will 
be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-Baseline muscle biopsy cannot be scheduled on the day of 
Visit 19 or Visit 41, it may be performed at a later date, as long as it is at least 2 weeks before dosing, for the biopsy at Visit 19 and within 1 month of the day of the visit for the 
biopsy at Visit 41.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 277
10.15.3. Clinical Laboratory Tests
The following safety laboratory tests will be performed at times defined in Sections 10.15.1 and 10.15.2 of this protocol. Additional 
laboratory results may be reported on these samples as a result of the method of analysis or the type of analyzer used by the clinical 
laboratory; or as derived from calculated values. These additional tests would not require additional collection of blood. Unscheduled 
clinical laboratory measurements may be obtained at any time during the study to assess any perceived safety concerns.
Table 5.
Protocol Required Safety Laboratory Assessments in Russia
CENTRAL LABORATORY TESTING
Clinical Safety
Hematology
Urinalysis
Other
Hemoglobin
Hematocrit
Red blood cell (RBC) count and morphology
Platelet count
White blood cell count (and morphology as applicable)
Total neutrophils (Abs)
Absolute neutrophils
Eosinophils (Abs)
Monocytes (Abs)
Basophils (Abs)
Lymphocytes (Abs)
Red blood cell indices (mean corpuscular volume, mean corpuscular 
hemoglobin, mean corpuscular hemoglobin concentration)
pH
Glucose (qual)
Protein (qual)
Blood (qual)
Ketones
Nitrites
Leukocyte esterase
Microscopy and culturea
Prothrombin time (PT)
activated partial 
thromboplastin time
C-reactive protein
Lipase
Amylase
Cystatin C
Haptoglobinb
Chemistry and Hepatic Safety
BUN and Creatinine
Glucose
Calcium
Sodium
Potassium
Chloride
Total CO2 (Bicarbonate)
AST, ALT
Total Bilirubin (direct and indirect bilirubin)
Alkaline phosphatase
Uric Acid
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 278
Table 5.
Protocol Required Safety Laboratory Assessments in Russia
Albumin
Total protein
Serum Phosphorus
Gamma glutamyl transferase (GGT)
Glutamate dehydrogenase (GLDH)
For Screening (Visit 1) and Day 360 (Visit 19) Only
International normalized ratio (INR)
Hepatitis A virus (anti-HAV) immunoglobulin M
Hepatitis B surface antigen
Hepatitis C antibody
For Post IP Intensified Safety Monitoring (at Year 1 and Year 2)
Complement biomarkers eg, C3 and C4, additional exploratoryc
Urine biomarkers
Other Assessments
Immunogenicity: NAb to AAV9; ELISpot to AAV9; ADA to AAV9; ELISpot to mini-dystrophin; ADA to mini-dystrophin
Viral vector shedding (whole blood, saliva, and urine)
Cardiac troponin I 
Creatine kinase
Conditional Testing
Genetic screening for aHUS-Central Laboratory, if needed as per Section 6.5.1
Local assessment of NT-ProBNP/BNP, if needed as per Section 8.2.7
LOCAL AND CENTRAL LABORATORY TESTING
Local Laboratory
Hematology: as per clinical safety panel, including blood smear for 
morphology. Absolute neutrophils are not required.
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Chemistry and hepatic safety: at a minimum, creatinine, BUN (or blood urea if 
BUN cannot be performed), calcium, sodium, potassium, chloride, total CO2
(bicarbonate), uric acid and serum phosphorus; but excluding AST and ALT-
sensitive clinical data
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cystatin C (when possible)
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Urinalysis: as per clinical safety panel
Day 6 to 10 (Visits 6 to 10) in Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 279
Table 5.
Protocol Required Safety Laboratory Assessments in Russia
Cardiac troponin I, (or cardiac troponin T if cardiac troponin I is not 
available)
Baseline Visit (Visit 2), Day 2 (Visit 4), Day 4 (Visit 5), Day 6 (Visit 6), 
Day 8 (Visit 8), and Day 10 (Visit 10) in Year 1
Day 390 (Visit 20), Day 391 (Visit 21), Day 393 (Visit 22), Day 395 (Visit 
23), Day 397 (Visit 25), and Day 399 (Visit 27) in Year 2
Serum creatinine
Baseline Visit, Day 2 and Day 4 (Visits 2, 4, and 5) in Year 1
Day 390 to Day 393 (Visits 20 to 22) in Year 2
Local Laboratory for Russia Only
Chemistry and hepatic safety
Baseline (Visit 2), Day 2 to Day 240 (Visit 4 to Visit 17) in Year 1d,e
Day 390 to Day 629 (Visit 20 to Visit 34) in Year 2d,e
Hematology
Screening Visit (Visit 1), Day 2 to Day 21 (Visit 4 to Visit 12), Day 34 
(Visit 13), Day 60 (Visit 14), Day 90 to Day 240 (Visit 15 to Visit 17) and 
Day 360 (Visit 19) in Year 1f
Day 391 to Day 410 (Visit 21 to Visit 29), Day 423 (Visit 30), Day 449 
(Visit 31) and Day 479 to Day 629 (Visit 32 to Visit 34) in Year 2
Cystatin C (when possible)
Day 2 to Day 240 (Visit 4 to Visit 17) in Year 1
Day 390 to Day 629 (Visit 20 to Visit 34) in Year 2
GLDH (when possible)
Day 2 to Day 240 (Visit 4 to Visit 17) in Year 1
Day 390 to Day 629 (Visit 20 to Visit 34) in Year 2
Urinalysis
Day 1 to Day 21 (Visit 3 to Visit 12) in Year 1
Day 390 to Day 410 (Visit 20 to Visit 29) in Year 2
Cardiac I, (or cardiac troponin T if cardiac troponin I is not available)
Baseline Visit (Visit 2), Day 2 (Visit 4), Day 4 (Visit 5), Day 6 (Visit 6), 
Day 8 (Visit 8), and Day 10 (Visit 10), Day 21 to Day 120 (Visit 12 to 
Visit 16) in Year 1.
Day 390 to Day 509 (Visit 20 to Visit 33) in Year 2
Coagulation
Screening Visit (Visit 1), Day 2 to Day 21 (Visit 4 to Visit 12), Day 34 
(Visit 13), Day 60 (Visit 14), Day 90 to Day 240 (Visit 15 to Visit 17) in 
Year 1
Day 391 to Day 410 (Visit 21 to Visit 29), Day 423 (Visit 30), Day 449 
(Visit 31) and Day 479 to Day 629 (Visit 32 to Visit 34) in Year 2
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 280
Table 5.
Protocol Required Safety Laboratory Assessments in Russia
Central Laboratory
Clinical safety 
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
Chemistry and hepatic safety 
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
Urinalysis 
Days 2 and 4 (Visits 4 and 5) in Year 1
Days 391 and 393 (Visits 21 and 22) in Year 2
GLDH
Day 9 (Visit 9) at Year 1
Day 398 (Visit 26) at Year 2
C3, C4
Days 6 to 10 (Visits 6 to 10) at Year 1
Day 395 to 399 (Visits 23 to 27) in Year 2
Cardiac troponin I
Day 7 (Visit 7) at Year 1
Day 396 (Visit 24) at Year 2
a.
Only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. Culture to be done locally.
b.
Only for the Screening Visit (Visit 1) and for Day 360 Visit (Visit 19).
c.
Additional biomarkers, such as ferritin, will be included so long as blood volume limits are not exceeded.
d.
Only creatinine is required at Baseline Visit (Visit 2) in Year 1 and on Day 390 (Visit 390) in Year 2.
e.
ALT and AST will not be analyzed locally, those samples will be sent to the central laboratory to prevent the results being shared with the site or the 
Sponsor (Section 6.3).
f.
On Day 360 (Visit 19) the results of neutrophils and platelets are considered sensitive clinical data and are not shared with the site or the Sponsor. They 
will only be shared with the unblinded medical monitor so he/she can perform the determination of eligibility for Year 2 IP administration (Section 6.3.3). 
The local laboratories at the Russian sites will follow the same process.
Any remaining biospecimens samples collected for clinical safety be retained and stored for the duration of the study. Retained 
samples may be used for the assessment of exploratory biomarkers. These data will not be included in the clinical study report. 
Investigators must document their review of each laboratory safety report.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 281
10.16. Appendix 16: Israel Appendix
10.16.1. Schedule of Activities – Year 1 (Screening to Year 1 Day 360)
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Informed 
consent/assent
X
Inform caregivers 
about study 
C3391007dd
X
Demography
X
Medical history
Xii
Medication history
X
Review of 
inclusion/exclusion 
criteria
X
X
Eligibility for Year
1 IP 
administrationv
X
Hospital stayjj
X




X
Physical 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological 
examinationh
X
X
X
X
X
X
X
X
X
X
X
X
Weight
X
X
X
X
X
X
X
Height
X
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 282
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Vital signs (supine 
BP, respiratory 
rate, PR, body 
temp, and O2 
saturation)i,j
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGk
X
X
X
X
X
X
CBCL
X
X
X
g
Randomization
Xbb
Laboratory Assessmentsl
Blood Samples
NAb
X
(X)cc
X
X
X
g
ADA to 
mini-dystrophin 
and AAV9
X
Xff
Xff
Xff
X
X
X
X
g
ELISpot to 
mini-dystrophin 
and AAV9
X
X
X
g
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
g
Clinical safety 
(hematology, 
other)l
X
X
X
X
X
X
X
X
X
X
X
X
g
Chemistry and 
hepatic safety l
X
X
X
X
X
Xee
X
X
X
X
X
X
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
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Page 283
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Post IP intensified 
safety 
monitoringl,w
X
X
X
X
X
Local and central 
laboratory testingaa
Xll
X
X
X
X
X
X
X
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Xll
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
International 
normalized ratio 
(INR),
Hepatitis A virus 
(anti-HAV) 
immunoglobulin M 
Hepatitis B surface 
antigen,
Hepatitis C 
antibodyl
X
X
Biomarker 
(creatine kinase) l
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked 
biospecimens for 
biomarkersm
X
X
X
Banked 
biospecimens for 
geneticsn
X
Urine Samples
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 284
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Clinical safety 
(urinalysis)l
X
X
X
X
X
X
X
X
X
X
g
Banked 
biospecimens for 
biomarkersm
X
X
X
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Saliva Samples
Viral Vector 
Sheddingz
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
g
Tissue Samples
Muscle biopsyo
X
Xx
Imaging 
Assessments
Echocardiogramp
X
X
X
g
Cardiac MRIgg
Xhh
Xhh
Functional Assessments
FVCq, y
X
X
X
g
NSAAq
X
X
X
X
X
X
X
Ankle range of 
motion 
X
X
X
X
X
X
X
Ambulatory status
Xr
X
X
X
X
X
Actigraphys
X
X
X
X
X
Clinical Outcome Assessments
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 285
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Caregiver-completed
Modified PODCI –
Pediatric Parentt
X
X
X
X
EQ-5D-Y Proxyt
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGt
X
X
X
X
X
X
Participant-completed
EQ-5D-Yt
X
X
Clinical evaluator-completed
CGISq
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
WPAI:DMD 
Caregiver
X
Interventions
Protocol-mandated 
glucocorticoid 
regimenu
X
X













X
Background 
glucocorticoid 
regimen
X
X
X




IP administration
X
Meningococcal 
vaccine
X
X
Ongoing 
monitoring
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 286
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
Concomitant 
medications
X





















X
Serious and 
nonserious adverse 
event monitoring 
X





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9=adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG=electrocardiogram; ELISpot=Enzyme-Linked ImmunoSpot; EQ-5D-Y=EuroQol 5 
Dimensions–Youth; FVC=Forced Vital Capacity; IP=investigational product; Men ACWY=Meningococcal serogroups A, C, W, and Y; NAb=neutralizing antibodies; 
NSAA=North Star Ambulatory Assessment; PGIS=patient global impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; temp=temperature; PR=pulse 
rate. Schedule of Activities – Year 2 and Long-Term Follow Up
a.
Visit 1 – Screening Visit 

During screening, participants and caregiver(s) will be assessed for study eligibility in accordance with the Inclusion/Exclusion Criteria as described in Section 5.1 and 
Section 5.2; 

Visit 1 must be conducted over the course of 2 days. The investigator will decide which of the schedules below they will follow and inform the study team:

Schedule A:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. Second day: should take place the next day or as soon as possible, 
after the first day: clinical safety (See Appendix 2), INR, cardiac troponin I.

Schedule B:

First day: collection of blood, urine and saliva for anti-HAV immunoglobulin M, hepatitis B surface antigen, hepatitis C antibody, NAb to AAV9, ADA to 
mini-dystrophin and AAV9, banked biospecimens for biomarkers and viral vector shedding. Second day: must take place only when the results of the test for 
NAb to AAV9 are available. The time between the first and second day of the Screening Visit is expected to be between 3-4 weeks (based on the time to 
obtain the results of the NAb to AAV9 test). Only participants with a negative test for NAb to AAV9 will perform the rest of the Visit 1 assessments as per 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 287
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
SoA. This includes the collection of blood and urine for: clinical safety tests (see Appendix 2), INR and cardiac troponin I. Participants with a positive test for 
NAb to AAV9 will be screen failed and will not attend the second day of Screening Visit (Visit 1).

Informed consent must be provided by the caregiver(s). The participant may also be required to provide assent in compliance with local regulations and institutional 
review board (IRB) requirements;

Screening blood tests with results considered by the Investigator to be transient and inconsistent with the participant’s clinical condition may be repeated once during the 
screening period for confirmation of eligibility;

Demographics: Information such as date of birth, race and ethnicity and gender will be collected in compliance with local regulations;

Medical history will include results of genetic testing for confirmation of diagnosis of DMD. Results must confirm the presence of an abnormality (eg, deletion, 
duplication), or a point mutation in the dystrophin gene(s) which is consistent with the diagnosis of DMD. The mutation type will be reported. If the Investigator 
determines that the results are inconclusive, a repeat genetic testing will be allowed through the central laboratory at Screening (Visit 1) prior to any other assessments. 
In that case participants may return for the remainder of Screening (Visit 1) once results are confirmed (Section 8.7.1);

Medical history will also be reviewed for any significant medical history and concurrent illness(es) that required or are requiring specialist consultation or treatment;

Medication history: Complete medication history will include all prescription or nonprescription drugs, and dietary and herbal supplements taken within 30 days prior to 
the Screening Visit (Visit 1). The date the participant first started glucocorticoids for their DMD and the date of start of the background glucocorticoid regimen that the 
participant is taking at the time of Visit 1 (Screening Visit) must also be documented. In addition, the general immunization status including the immunization status 
against meningococcus, and any other vaccine(s) required by the eculizumab local prescribing information, must be documented;

Meningococcal vaccine: Participants who have no contraindications and who have not previously received a MenACWY vaccination; or whose last vaccination at the 
time of the Screening Visit (Visit 1) is outside the time period of active coverage specified by the vaccine manufacturer (Visit 1) must receive at least one dose of 
MenACWY vaccine as early as possible in the Screening Period and not later than 30 days before IP administration (see Section 6.5.1). Participants must also receive 
MenB vaccination if indicated by national vaccination guidelines. In addition, local eculizumab prescribing information, including additional vaccination and other 
requirements must also be followed (see Section 6.5.1).

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6).
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PFIZER CONFIDENTIAL
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Page 288
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
b.
Visit 14 and Visit 19 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern 
and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood 
collection, may be performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory samples must be collected: 
Visit 14 (Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
Visit 19 (Week 52)
First day: anti-HAV immunoglobulin M, Hepatitis B surface antigen, Hepatitis C antibody (these tests will not be applicable for Cohort 1 participants confirmed to 
meet exclusion criterion 15 [see Section 5.2]), NAb to AAV9, ADA to mini-dystrophin and AAV9, banked biospecimens for biomarkers, viral vector shedding. 
Second day: clinical safety, INR, cardiac troponin I, biomarker (creatine kinase). 
c.
Visit 2 – Baseline Visit

Meningococcal vaccine: Only applicable for participants who have not received this vaccination at Screening (please refer to footnote a);

For sites outside the US, the Baseline visit should occur at least 31 calendar days prior to the planned IP administration visit, Day 1 (Visit 3), to allow for timely delivery 
of IP to the site, unless notified of earlier or later IP delivery by the study team. For US sites the Baseline visit should occur at least 16 calendar days prior to the planned 
IP administration visit, Day 1 (Visit 3), to allow for timely delivery of IP to the site, unless notified of earlier or later IP delivery by the study team; 

IP will be shipped to site following confirmation of participant’s eligibility (Section 5.1 and Section 5.2) and randomization. The amount of IP to be shipped to the site 
for IP administration at Visit 3 will be based on the measurement of body weight at the Baseline Visit (Visit 2). Body weight measurement must be verified by two site 
personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site.

Unplanned Visit: If the 90-day period between screening and dosing is exceeded due to operational or administrative reasons (eg, enrollment pause due to regulatory or 
safety review, operational issues causing significant delays), participants will not be screen failed/withdrawn from the study, but will repeat some tests and assessments 
to re-confirm study/IP administration eligibility criteria, and to rule out significant changes in key tests and assessments (see Sections 5.3 and 5.6)
d.
Visit 3 – Week 1, Day 1 (Day of IP administration)
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Page 289
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

Prior to IP administration, the Investigator must confirm applicable IP eligibility criteria (Section 6.1.1);

Participants will be instructed not to take their background glucocorticoid dose on Day 1 (Visit 3);

Participants are to be admitted to the site;

The following assessments must be performed prior to IP administration: physical examination, urine sample collection, ECG and vital signs; 

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone 1 to 4 hours prior to infusion of IP; 

IP administration over approximately 2 to 4 hours (-15 minutes to +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site to enable prompt follow-up in the event of any emergent AEs through Day 14 (Visit 11), or longer if deemed necessary.
e.
Visits 12, 12.2, 13.2, 14.2 and 15

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
f.
Visit 18

This visit may be performed remotely (at or close to the participant’s home); in that case, it should include phone communication between site staff and 
participant/caregiver to discuss any adverse events and/or changes to concomitant medications.

Amount of IP to be shipped to site for the IP administration on Day 390 (Visit 20) will be based on the measurement of body weight obtained at this visit. Body weight 
measurement must be verified by two site personnel and entered into the interactive response technology drug management system to trigger IP shipment to the site. 
This visit is not applicable for Cohort 1 participants confirmed to meet exclusion criterion 15 (see Section 5.2).
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 290
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7

For participants who undergo Day 328 (Visit 18) during a study dosing pause, the amount of IP to be shipped to the site will be determined once the study has been 
restarted. Therefore, the weight collected at Day 328 (Visit 18) will not be entered into the interactive response technology drug management system during the dosing 
pause. Participants will be evaluated for Year 2 IP eligibility when the study is restarted.

May not be applicable for participants confirmed to meet exclusion criterion 15 or those who declined Year 2 IP administration (see Appendix 12 and Section 7.2.1).
g.
Early Discontinuation Visit

This visit is not applicable for participants who withdraw prior to Day 1 (Visit 3) or for Cohort 2 participants who are withdrawn from the study between Day 360 (Visit 
19) and Day 390 (Visit 20) (see Section 7.1).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only if the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
h.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable post-baseline unless safety concerns warrant full examination.
i.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
j.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
k.
12-Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 291
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
l.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 

For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 

On the following visits: Baseline Visit (Visit 2), Day 60 (Visit 14), Day 120 (Visit 16), Day 240 (Visit 17) and Day 360 (Visit 19), in which functional assessments 
(eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the functional test; for 
additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
m.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
n.
Banked biospecimens for genetics are collected as described in Section 8.7.2.
o.
Open muscle biopsies will be obtained in approximately the first 15 participants randomized into Cohorts 1 and 2, and their siblings (with the potential to collect a 
maximum of 33 if needed), at sites that have been trained and certified by the Sponsor/Sponsor designee to collect open muscle biopsies, following administration of an 
anesthetic (eg, regional block or under general anesthesia) according to institutional standard practice, and only after any imaging and functional assessments scheduled for 
the same visit have been completed.  Baseline Visit muscle biopsies will be performed after randomization. If a muscle biopsy cannot be scheduled on the day of the 
Baseline Visit, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing.
p.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
q.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, ankle range of motion and FVC may be video recorded at the Day 1 
(Screening Visit), Baseline Visit (Visit 2), and at the annual visits (ie, Visits 19, 35, 37, 39, 41, 43). If CE re-training is required, the assigned master physiotherapist may 
request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments should be performed early in the course of the visit, to help reduce 
the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
r.
Ambulatory assessment at Screening (Visit 1) is based only on the ability to perform the 10 m run/walk, as assessed during the NSAA.
s.
An activity monitor will be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 292
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
t.
COAs will be completed by the caregiver on behalf of the participant and/or by the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
u.
Starting on Day 1 (Visit 3) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1).
v.
For eligibility for Year 1 IP administration please see Section 6.1.1.
w.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
x.
All participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo 2 post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-baseline muscle biopsy cannot be performed on the 
scheduled day, the biopsy may be performed at a later day, as long as it is at least 2 weeks before dosing for the biopsy at Visit 19 and within 1 month of the day of the visit for
the biopsy at Visit 41.
y.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
z.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) only after IP administration, as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a 
particular matrix (sample type) will be stopped when at least 2 consecutive negative results are observed in that matrix. See Section 8.8.5 for additional details.
aa.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 9 will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data.  C3/C4 will also be sent to the central laboratory at Visits 6, 7, 8, 9, and 10. For more 
details, please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 4 and 5, see Appendix 2 for details.
bb. In order to ensure an adequate understanding and management of potential safety risks, the initial rate of randomization into the study will be limited. No more than 2 
participants per week will be randomized at the start of the study, until 4 participants have been observed for at least 2 weeks post IP administration. After that, the rate could 
be increased to no more than 3 participants randomized per week (until at total of 10 participants have been observed for at least 2 weeks post-IP administration). Thereafter, 
the rate of randomization could be further increased to no more than 5 participants randomized per week (until a total of 20 participants have been observed for at least 2 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 293
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
weeks post-IP administration). After this time, no limits of the randomization rate will be imposed unless the study team, in consultation with the E-DMC, determines 
otherwise. For more details- please see Section 4.1.
cc.
The NAb to AAV9 blood samples at the Baseline Visit (Visit 2) will always be collected and sent to the Central Laboratory, but will only be analyzed and reviewed prior to 
Day 1 Visit (Visit 3) if the time between the first blood draw for NAb to AAV9 testing at the Screening Visit (Visit 1) or most recent test, if repeat blood draw(s) was required, 
and the Day 1 Visit (Visit 3) is expected to be more than 55 days, which is anticipated to occur rarely. Dosing cannot occur unless there is a negative test to AAV9 from a 
sample collected 55 or less days before the day of IP administration.
dd. For US sites, only when approved by the relevant Institutional Review Board.
ee.
On Day 28 (Visit 12.2), only GLDH will be collected.
ff.
ADA to mini-dystrophin only.
gg. Investigators will discuss with the participant and/or their caregiver the importance of having a baseline cardiac MRI, even under general anesthesia, to be able to assess and 
manage potential cardiac adverse events during the study. This discussion and the decision to perform or not a baseline cardiac MRI will be documented in the participant's 
records. A participant requiring anesthesia or unable to undergo investigation with closed MRI (eg, metal implants) may be exempt, and will be allowed to be randomized in 
the study without a cardiac MRI. Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration 
(Section 2.3.3.7). If the site considers gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast 
administration will be performed. It is important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may 
be required in certain situations (Section 8.2.8).
hh. Cardiac MRI may be performed at any time between the first day of the Screening Visit (Visit 1) and the Day 1 Visit (Visit 3), and after randomization, as long as it is done 
before Day 1 (Visit 3). If a prior cardiac MRI was performed within 6 months of the Screening Visit (with gadolinium, or without gadolinium if contrast administration is 
contraindicated), and results are available, then a cardiac MRI at screening will not be performed. Only participants with a pre-IP administration cardiac MRI will have a 
follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35).
ii.
Participants will be assessed by a cardiologist at the Screening Visit, see Section 5.2, exclusion criteria 16 and 17.
jj.
Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 8, or later if deemed 
necessary by the Investigator (see Section 8.2.10). 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 294
Period
Screeni
ng
Baseli
ne
Main Study Period (Year 1)
Early Discontinuation Visit g
Visit Number/
Description
Visit 1a
Visit 
2c
Visit 
3d
Visit 
4
Visit 
5
Visit 
6
Visit 
7
Visit
s 8 
&
9
Visit 
10
Visit 
11
Visit 
12e
Visit 
12.2e
Visit 
13
Visit 
13.1kk
Visi
t 
13.2
e
Vis
it 
14b
Visit 
14.2e
Visit 
15e
Visit 
16
Visit 
17
Visit 
18f
Visit 
19b
Screeni
ng
Baseli
ne
Wee
k 1, 
Day 
1
Wee
k 1, 
Day 
2
Wee
k 1, 
Day 
4
Wee
k 1, 
Day 
6
Wee
k 1, 
Day 
7
Wee
k 2, 
Day 
8 & 
9
Wee
k 2, 
Day 
10
Wee
k 2, 
Day 
14
Wee
k 3
Wee
k 4
Week 
5
Week 
6
We
ek 7
W
ee
k 9
Wee
k 11
Wee
k 13
Wee
k 18
Wee
k 35
Wee
k 47
Wee
k 52
Visit Day
-90 to -
30
-48 to 
-16
1
2
4
6
7
8 & 
9
10
14
21
28
34
42
48
60
74
90
120
240
328
360
Visit Window 
(± days)
0
0
0
0
0
0
0
1
1
1
1
3
3
3
3
3
7
7
14
7
kk. This visit is for sites in Germany only and only to test cardiac troponin I. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s 
preference warrants in-person visit, this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local 
phlebotomist, as well as phone communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ll.
Only for sites in Russia 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
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Final Protocol Amendment 15, 28 December 2023
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Page 295
10.16.2. Schedule of Activities – Year 2 and Long Term Follow Up
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Eligibility for Year 2 IP 
administrationr
X
Hospital staydd
X




X
Physical examinationg
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Neurological examinationg
X
X
X
X
X
X
X
X
X
X
X
X
Height and Weight
X
X
X
X
X
X
X
Vital signs (supine BP, 
respiration, PR, body temp, 
and O2 saturation)h,i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
12-Lead ECGj
X
X
X
X
X
X
CBCL
X
X
X
Xe
Laboratory Assessmentsk
Blood Samples
 NAb to AAV9
X
X
X
Xe
  ADA to mini-dystrophin 
and AAV9
Xz
Xz
Xz
X
X
X
X
Xe
  ELISpot to mini-
dystrophin and AAV9
X
X
Xw Xe
Viral Vector Sheddingu
X
X
X
X
X
X
Xe
Clinical safety 
(hematology, other)k
X
X
X
X
X
X
X
X
X
X
X
X
Xe
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 296
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Chemistry and hepatic 
safetyk
X
X
X
X
Xy
X
X
X
X
X
X
X
X
X
X
Post IP intensified safety 
monitoringk,s
X
X
X
X
X
Local and central 
laboratory testingx
X
X
X
X
X
X
X
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Xgg
Cardiac Troponin I
X
X
X
X
X
X
X
X
X
X
X
X
X
Biomarker (creatine 
kinase)k
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Banked biospecimens for 
biomarkersl
X
X
Urine Samples
Clinical safety (urinalysis)k
X
X
X
X
X
X
X
X
X
X
Xe
Banked biospecimens for 
biomarkersl
X
X
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Saliva Samples
Viral Vector Sheddingu
X
X
X
X
X
X
X
X
Xe
Tissue Sample
Muscle Biopsy
Xff
Imaging Assessments
Echocardiogramm
X
X
Xe
Cardiac MRIaa
Xaa
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 297
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Functional Assessments
FVCn,t
X
X
Xe
NSAAn
X
X
X
X
X
X
X
Ankle range of motion 
X
X
X
X
X
X
X
Ambulatory status
X
X
X
X
X
X
X
Actigraphyo
X
X
X
X
X
X
Clinical Outcome Assessments
Caregiver-completed
Modified PODCI –
Pediatric Parentp
X
X
X
X
X
EQ-5D-Y Proxyp
X
X
X
EQ-5D-5L
X
X
X
PGIS:CGp
X
X
X
X
X
X
X
Participant-completed
Modified PODCI –
Adolescentp
X
X
X
EQ-5D-Yp
X
X
X
PGISp
X
X
X
Clinical evaluator-completed
CGISn
X
X
X
X
X
X
X
Health economic questionnaires
HRU:CG
X
X
X
WPAI:DMD Caregiver
X
X
X
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 298
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
Study Interventions
Protocol-mandated 
glucocorticoid regimenq
X
X













X
Background glucocorticoid 
regimen
X



Xv
Xv
IP administration
X
Ongoing monitoring
Concomitant medications





















X
Serious and nonserious 
adverse event monitoring





















X
Abbreviations/Acronyms: →=continuous monitoring/event; AAV9= adeno associated virus serotype 9; ADA=anti-drug antibody; BP=Blood pressure; CG=Caregiver; 
CGIS=Clinician Global Impression of Severity; CBCL=Child Behavior Check List; ECG = electrocardiogram; ELISpot= Enzyme-Linked ImmunoSpot; EQ-5D-Y= EuroQol 5 
Dimensions–Youth; FVC= Forced Vital Capacity; IP=investigational product; NAb=neutralizing antibodies; NSAA=North Star Ambulatory Assessment; PGIS= patient global 
impression of severity; PODCI=Pediatric Outcomes Data Collection Instrument; PR=pulse rate; temp=temperature.
a.
Visit 20 – Year 2, Week 1, Day 1

Prior to IP administration, the Investigator must confirm applicable Year 2 IP administration eligibility criteria (Section 7.1);

Participants are to be admitted to the site;

Participants will be instructed not to take their background glucocorticoid dose on Day 390 (Visit 20);

The following assessments must be performed prior to IP administration: Physical examination, blood collection (ELISpot to mini-dystrophin and AAV9), urine sample 
collection, ECG and vital signs; 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 299
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f

Participants will receive an intravenous infusion of 2 mg/kg of methylprednisolone approximately 1 to 4 hours prior to infusion of IP;

IP administration over approximately 2 to 4 hours (-15 minutes or +30 minutes including flush);

Vital signs will be monitored at approximately 30 minutes, 1, 2, 4, 8, and 10 hours after start of infusion, and 3 times per day after that for the duration of the hospital 
stay. Participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed necessary by the 
Investigator (see Section 8.2.10).

If adverse events (AEs) possibly related to IP administration are observed, participants should not be discharged until the events have resolved. Upon discharge, 
participants should stay near the site for at least 7 additional days to enable prompt follow-up in the event of any emergent AEs through Day 403 (Visit 28), or longer if 
deemed necessary.

If the time between the blood draw for the clinical safety laboratory tests on Day 360 Visit (Visit 19) and the planned Day 390 Visit (Visit 20) exceeds 13 weeks 
(90 days), due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), then the 
clinical safety laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP. The participant will not be withdrawn due to exceeding the time 
between Day 360 Visit (Visit 19) and Day 390 Visit (Visit 20), as described in Section 7.1.

If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays), a participant’s Year 
2 IP administration must be delayed, the Day 390 (Visit 20) and also subsequent visits will be delayed for that participant until the pause is lifted. If the pause is not lifted 
within 6 months of the Day 360 (Visit 19), the participant will undergo an unplanned visit for general monitoring on Day 540 ±7 days, and approximately every 6 months 
afterwards until the pause is lifted (or more frequently if considered necessary by the investigator) for sites in Israel.
b.
Visits 29, 29.2, 30.2, 31.2, and 32

Unless clinical concern and/or participant preference and/or the site’s institutional review board’s preference warrants in-person visit, this visit may be performed 
remotely, and would include blood collection at or close to the participant’s home coordinated by local phlebotomist, as well as phone communication between site staff 
and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 300
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
c.
Visit 31 must be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. Unless clinical concern and/or participant 
preference and/or the site’s institutional review board’s preference warrants in-person visit, the follow-up day visit, on the second day, to complete blood collection, may be 
performed remotely, to allow blood collection at or close to the participant’s home. The following laboratory assessments must be collected as follows: 
Visit 31 (Year 2, Week 9)
First day: ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase). 
d.
Visit 42 and 43 – Long-term follow up Year 6

All participants will be followed for 5 years after receiving fordadistrogene movaparvovec. Therefore Visits 42 and 43 only apply to participants randomized to Cohort 2.
e.
Early Discontinuation Visit

This visit is not applicable for Cohort 2 participants who were withdrawn from the study between Day 360 (Visit 19) and Day 390 (Visit 20) (see Section 7).

The site will contact the Sponsor to determine which laboratory (blood) tests should be collected at the Early Discontinuation Visit, to ensure that the daily and 4-week 
maximum blood volume limits are not exceeded.

CBCL questionnaire: Only if the previous CBCL questionnaire was completed more than 2 months before the date of the Early Discontinuation Visit.

NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9: Only if the participant discontinues the study before Visit 37 (Year 3, Day 
1110).

Clinical Safety: Only if the previous analysis had been done more than 1 month before the date of the Early Discontinuation visit.

Echocardiogram: Only if the previous echocardiogram had been done more than 6 months before the date of the Early Discontinuation Visit.

FVC: Only If the previous FVC had been assessed more than 2 months before the date of the Early Discontinuation Visit.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 301
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f

Viral vector shedding: For any given matrix, if the sample(s) had still being collected at the participant´s last study visit, it should also be collected at the Early 
Discontinuation Visit.
f.
Visit Windows for Visits 20 through Visit 43

The number of days between each visit for Visit 20 (Year 2, IP administration) through Visit 43 must be maintained irrespective of the actual visit day of Visit 20, eg, if 
the actual visit day at Visit 20 is 392 (instead of 390), then Visit 21 will take place on Day 393 (instead of Day 391), etc.
g.
Brief physical and neurological examinations, as described in Section 8.2, are acceptable unless safety concerns warrant full examination.
h.
O2 saturation will only be measured before the start of the IP infusion and during the inpatient stay post IP administration.
i.
Vital signs will be measured 3 times per day during the inpatient stay post IP administration.
j.
12 Lead ECG will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation. 
k.
Clinical laboratory tests are described in detail in Table 3 (Appendix 2). 
For urinalysis, a microscopic analysis will be performed only if urine dipstick is positive for blood, protein, nitrites or leukocyte esterase. 
If the time between the blood draw for the clinical safety laboratory tests on Visit 19 (Day 360) and the planned Visit 20 (Day 390) exceeds 13 weeks (90 days due to 
operational or administrative reasons [eg, enrollment pause due to regulatory or safety review, operational issues causing significant delays]), then the clinical safety 
laboratory tests should be repeated and eligibility (re)confirmed prior to administering IP, but the participant will not be withdrawn due to exceeding the time between Visit 
19 (Day 360) and the planned Visit 20 (Day 390), as described in Section 7.1.
l.
Banked biospecimens for biomarkers are collected as described in Section 8.8.4.
m.
Echocardiograms will be collected and read locally for immediate interpretation and safety monitoring and will be submitted to a central laboratory for standardized 
interpretation.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 302
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
n.
The NSAA and CGIS will be administered by a single clinical evaluator at each visit and whenever possible, the same CE should administer the functional assessments 
(NSAA, ankle range of motion and FVC) for the same participant throughout the study. The NSAA, range of motion and FVC may be video recorded at the annual visits. If 
CE re-training is required, the assigned master physiotherapist may request additional visits to be recorded and reviewed. Whenever possible, motor functional assessments 
should be performed early in the course of the visit, to help reduce the effect of fatigue on the participants´ performance; for additional advice regarding the ordering of 
assessments please consult the Functional Assessment Manual. On the following visits: Day 449 (Visit 31), Day 509 (Visit 33), Day 629 (Visit 34) and Day 749 (Visit 35), in 
which functional assessments (eg, NSAA) are performed, blood draws should always be done first, whenever possible, to ensure that the CK levels are obtained prior to the 
functional test; for additional advice regarding the ordering of assessments please consult the Functional Assessment Manual.
o.
An activity monitor may be placed on the participant’s ankle prior to the performing of other functional assessments and is to be worn continuously for the subsequent 2 
weeks.
p.
COAs will be completed by the caregiver on behalf of the participant and/or the participants themselves, depending on the participant’s age and at the discretion of the 
Investigator and caregiver, as described in Section 8.1.7.
q.
Starting on Day 390 (Visit 20) participants will not take their background glucocorticoid regimen. Participants will replace their background glucocorticoid regimen with the 
protocol-mandated glucocorticoid regimen for 90 days post-IP administration, after which, as long as there is no immune response or other clinical indication, participants 
may return to their background glucocorticoid regimen (see Section 6.5.1). If, due to operational or administrative reasons (eg, enrollment pause due to regulatory or safety 
review, operational issues causing significant delays), participants must delay Year 2 IP administration, they will not receive the protocol-mandated glucocorticoid regimen 
until the pause is lifted and Year 2 IP administration takes place; they will remain on their background glucocorticoid regimen until then.
r.
For eligibility for Year 2 IP administration please see Section 7.1.
s.
For details regarding post IP intensified safety monitoring please see Section 8.2.10.
t.
FVC will be assessed throughout the study on participants who are ≥6 years old at Screening. Participants <6 years old at the Screening Visit (Visit 1) will not have FVC 
evaluated at any time during the study.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 303
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
u.
Viral vector shedding will be measured in approximately the first 45 treated participants (approximately 30 treated with fordadistrogene movaparvovec and approximately 
15 treated with placebo) as described in Section 8.8.5. For each of the approximately 45 first treated participants, sample collection for a particular matrix (sample type) will 
be stopped when at least 2 consecutive negative results are observed in that matrix.
v.
After two years (Day 749), any change to the background glucocorticoid regimen will be permitted (see Section 6.5.1).
w.
ELISpot to mini-dystrophin and AAV9 if a clinical event has occurred that, in the opinion of the Sponsor and/or the Investigator, could be due to an immunological reaction. 
If ELISpot is to be collected, these visits should be conducted in the course of two (preferably consecutive) days in order to comply with daily blood volume limits. The 
following laboratory assessments must be collected as follows:
First day: NAb to AAV9, ADA to mini-dystrophin and AAV9, ELISpot to mini-dystrophin and AAV9, viral vector shedding.
Second day: clinical safety, cardiac troponin I, biomarker (creatine kinase).
x.
Urine and some blood samples will be collected for local laboratory testing to ensure fast turnaround of test results. Some blood samples ie, GLDH at Visit 26  will be sent to 
the central laboratory to prevent sharing the results of ALT/AST sensitive clinical data. C3/C4 will also be sent to the central laboratory at Visits 23, 24, 25, 26, 27. For more 
details please see Section 8.2.12 and Appendix 2. For sites in Japan only: additional local laboratory tests will be collected at Visits 21 and 22, see Appendix 2 for details.
y.
On Day 417 (Visit 29.2), only GLDH will be collected.
z.
ADA to mini-dystrophin only.
aa.
Sites will be responsible for confirming participant eligibility to undergo MRI scanning and gadolinium contrast administration (Section 2.3.3.7). If the site considers 
gadolinium contrast administration unsafe, or if the participant has a history of allergy to gadolinium, cardiac MRI without contrast administration will be performed. It is 
important that the investigator discusses with the participant and/or caregivers that a cardiac MRI even under general anesthesia may be required in certain situations 
(Section 8.2.8). Only participants with a pre-IP administration cardiac MRI will have a follow-up cardiac MRI on Day 360 (Visit 19) and on Day 749 (Visit 35). 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 304
Period
Year 2
Long-term 
follow up
Early Discontinuation Visit e
Visit 
Number/Description
Visit 20a,bb, cc Visit 
21bb,
cc
Visit 
22bb,
cc
Visit 
23bb,
cc
Visit 
24bb, cc
Visit 
25bb,cc& 
26bb,cc
Visit 
27bb,
cc
Visit 
28bb,
cc
Visit 
29b,
bb, cc
Visit 
29.2b, 
bb, cc
Visit 
30bb, cc
Visit 
30.1ee,
bb,cc
Visit 
30.2b, bb,
cc
Visit 
31c,cc
Visit 
31.2b,cc
Visit 
32b,cc
Visit 
33
Visit 
34
Visit 
35
Visits 
36, 
38, 
40, 
42d
Visits 
37, 
39, 
41, 
43d
Year 2, Week 
1, Day 1
Year 
2, 
Week
1, 
Day 
2
Year 
2, 
Week 
1, 
Day 
4
Year 
2, 
Week 
1, 
Day 
6
Year 
2, 
Week 
1, Day 
7
Year 2, 
Week 
2, Days 
8 &9
Year 
2, 
Week 
2, 
Day 
10
Year 
2, 
Week 
2, 
Day 
14
Year 
2, 
Week 
3
Year 
2, 
Week 
4
Year 
2, 
Week 
5
Year 
2, 
Week 
6
Year 2, 
Week 7
Year 
2, 
Week 
9
Year 
2, 
Week 
11
Year 
2, 
Week 
13
Year 
2, 
Week 
18
Year 
2, 
Week 
35
Year 
2, 
Week 
52
Years 
3, 4, 
5, 6d
Years 
3, 4, 
5, 6d
Visit Day
390
391
393
395
396
397& 
398
399
403
410
417
423
431
437
449
463
479
509
629
749
930, 
1290, 
1650, 
2010d
1110, 
1470, 
1830, 
2190d
Visit Window (± days)
3f
2f
2f
2f
2f
2f
2f
3f
3f
3f
3f
3f
3f
3f
3f
3f
7f
7f
7f
30f
30f
bb. Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not attend Visits 20 to 30.2 and therefore will not 
perform the corresponding tests and assessments. These participants will not receive their protocol-mandated glucocorticoid regimen at Year 2. For details on the 
retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
cc.
Cohort 1 participants confirmed to meet exclusion criterion 15 and participants who declined Year 2 IP administration will not receive their protocol-mandated glucocorticoid 
regimen at Year 2. For details on the retrospective assessment of exclusion criterion 15, please see Appendix 12 and Section 7.2.1.
dd. Following IP administration, participants will remain as inpatients for at least 7 days after the infusion has terminated and will be discharged on Day 397, or later if deemed 
necessary by the Investigator (see Section 8.2.10).
ee.
This visit is for sites in Germany only and only to test cardiac troponin I. Unless clinical concern and/or participant preference and/or the site’s institutional review board’s 
preference warrants in-person visit, this visit may be performed remotely, and would include blood collection at or close to the participant’s home coordinated by local 
phlebotomist, as well as phone communication between site staff and participant/caregiver to discuss any adverse events and/or changes to concomitant medications.
ff.
A participant who has a muscle biopsy at the Baseline Visit (Visit 2), and their siblings, will undergo two post-Baseline muscle biopsies.  The post Baseline muscle biopsies 
will be performed on Day 360 (Visit 19) in Year 1 and on Day 1830 (Visit 41) during Long Term Follow-Up.  If the post-Baseline muscle biopsy cannot be scheduled on the 
day of Visit 19 or Visit 41, it may be performed at a later date, as long as it is at least 2 weeks before dosing, for the biopsy at Visit 19 and within 1 month of the day of the 
visit for the biopsy at Visit 41.
gg. Only for sites in Russia
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 305
10.17. Appendix 17: Protocol Amendment History
The Protocol Amendment Summary of Changes Table for the current amendment is located 
directly before the table of contents (TOC). The protocol amendment summary of changes 
tables for past amendment(s) can be found below:
Document History
Document
Version Date
Summary of Changes and Rationale
Amendment 14
07 June 2023
 
 
 
 
In Section 8.2.7, added instructions that for events 
of elevated troponin or myocarditis with or without 
abnormal findings in the initial cardiac MRI, a 
follow-up cardiac MRI will be performed 
approximately 3 months after the start of the event. 
This update was done to ensure adequate follow-up 
of events of elevated troponin or myocarditis.
In Section 8.2.7, added clarification for cases of 
elevated troponin meeting protocol criteria for 
further follow-up to repeat troponin and NT-
ProBNP tests (or BNP, if NT-ProBNP is not 
available) approximately every 48-72 hours) until 
each test returns to Baseline values or reaches a 
level considered not clinically significant by the 
investigator. This update was done to ensure 
adequate follow-up of cases elevated troponin.
In Section 8.2.7 and 8.2.8 (for cardiac MRI) 
clarified that when cardiac images (ECG, 
echocardiogram, cardiac MRI) are performed 
during the evaluation of cases of elevated cTn-I 
meeting protocol criteria for further follow-up, the 
submission to the central reader should be done in 
less than 72 hours. This update was done to ensure 
adequate follow-up of cases elevated troponin.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)
CCI

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 306
Document History
Document
Version Date
Summary of Changes and Rationale
In Section 6.1 and in Appendix 10, clarified that IV 
methylprednisolone, oral prednisone, or 
prednisolone, deflazacort, eculizumab, antiemetics 
e.g., ondansetron and MenACWY vaccine are not 
subject to safety reporting in accordance with 
Japanese regulation requirements. This update was 
done to align with Japan reporting regulations for 
non-IP study interventions.
In Section 8.1.3, incorporated updates made by the 
Protocol Administrative Changes and Clarifications 
for Study C3391003 letter, dated 03 November 
2022 to indicate that not only a surgeon but also a 
healthcare professional with adequate experience, as 
evaluated by the Sponsor beforehand can perform 
muscle biopsies in the study. This update was done 
to address the fact that in some specialized DMD
centers muscle biopsies from patients with DMD 
are performed routinely by neurologists and not by 
surgeons.
In Section 8.2.10, added recommendation to keep 
the IV line in place for at least 48 hours post IP 
administration in case IV hydration or treatment is 
necessary due to nausea, vomiting, anorexia, etc.  
This recommendation was added to minimize the 
risk of participants experiencing volume depletion.
Amendment 13
06 April 2023
In Section 6.1, updated dosing so that nominal drug 
concentration is used for dose calculation instead of 
exact lot specific concentration. This will be 
implemented only for Year 2 IP administration 
when instructed by the Sponsor. This change was 
done to comply with a request by FDA to gain 
experience with dosing using a nominal titer during 
the Phase 3 clinical study.
In Section 8.2.11, added language to remind 
investigators to carefully monitor participants with 
mutations between exons 30-41 or at exon 55 to 
comply with a request by the French regulatory 
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 307
Document History
Document
Version Date
Summary of Changes and Rationale
authority, ANSM, and to align with the language in 
the ICD and in the IB.
In Sections 1.3.1, 1.3.2, 10.9.1.1, 10.9.1.2, 
10.10.1.1, 10.10.1.2, 10.14.1, and 10.14.2, added 
test for anti mini-dystrophin ADA at Visit 12 (Day 
21) and Visit 12.2 (Day 28) in Year 1 and at Visit 
29 (Day 410) and Visit 29.2 (Day 417) in Year 2 to 
facilitate the early detection of participants with 
high titers who may be at high risk to develop an 
immune reaction against the transgene mini-
dystrophin protein expressed in skeletal/cardiac 
muscle. This would allow an early intervention 
before overt signs and symptoms have developed.
In Sections 10.9.1.1 and 10.9.1.2, updated 
approximate blood volume at Visit 12 (Day 21) and 
Visit 29 (Day 410) from 10 ml to 12 ml; and at Visit 
12.2 (Day 28) and Visit 29.2 (Day 417) from 2.5 ml 
to 4.5 ml. The blood volumes collected at these 
visits have been increased due to the addition of anti 
mini-dystrophin ADA tests.
In Sections 5.3.1 and 5.3.2, added that for 
participants randomized with delayed IP 
administration who are re-confirmed to be eligible 
for Year 1 or Year 2 IP administration, the dose of 
IP will be re-calculated if there is a change in body 
weight > ±5% of the prior body weight
In Section 6.1, added IMP/NIMP/AxMPs 
information to existing study intervention table and 
added specific “Study Intervention(s)” table
In Sections 1.3.1, 1.3.2, 8.2.12, Appendix 2 and 
Appendix 15, incorporated changes to reflect 
Russian PACL on local and central laboratory 
testing (19 Dec 2022). Added local labs to 
Appendix 2. Added Appendix 15 – Russia 
Appendix
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 308
Document History
Document
Version Date
Summary of Changes and Rationale
In Sections 1.3.1, 1.3.1, Appendix 2 and Appendix 
14, clarified that at Day 42 (Visit 13.1) and at Day 
431 (Visit 30.1) only Cardiac Troponin I is 
assessed.
Changed all instances of “ELISpot to dystrophin “to 
“ELISpot to mini-dystrophin” throughout the 
document. 
In Section 3.1, deleted measurement of WPAI 
caregiver response at Year 1. 
In Section 10.2, changed “Total neutrophils” to 
“Absolute neutrophils” in Table 3 – Local 
Laboratory.
In Section 10.4, added “and barrier” to the title.
In Sections 10.9.1.1 and 10.9.1.2, corrected the 
shading to match the other SoA table.
In Section 10.9.1.2, corrected the Italy SoA to add 
Local/Central Lab Testing to Visit 20
In Sections 1.3.1, 1.3.2, 10.9.1.1, 10.9.1.2, 
10.10.1.1, 10.10.1.2, 10.14.1, and 10.14.2, footnote 
“a, clarified that the allowance to repeat screening 
blood tests with results considered by the 
Investigator to be transient and inconsistent with the 
participant’s clinical condition refers to blood tests.
On the title page, Sections 10.1.1; 10.1.3; 10.1.4; 
10.1.5; 10.1.6; 10.1.8, 10.1.9 and 10.1.10, updated 
to match the current Pfizer protocol template.
In Section 5.6, moved text regarding screen failures 
previously in Section 10.1.3.
In Section 1.1, removed all cross-references.
In Section 6.1.1, deleted an instance of ‘the” 
repeated in a paragraph.
090177e19f8f61a6\Approved\Approved On: 28-Dec-2023 17:35 (GMT)

Fordadistrogene movaparvovec
C3391003
Final Protocol Amendment 15, 28 December 2023
PFIZER CONFIDENTIAL
CT02-GSOP Clinical Protocol Template Phase 1 2 3 4 (04 September 2018)
Page 309
Document History
Document
Version Date
Summary of Changes and Rationale
Throughout the document, all instances of “PF-
06939926” were changed to “fordadistrogene 
movaparvovec” and all instances of “mini 
dystrophin” were changed to “mini-dystrophin”.
Amendment 12
12 September 
2022
In Section 1.3.1, 1.3.2, 4.1, 4.2.4, 2.3.3.2, 8.1.3, 
SoA, included an additional muscle biopsy at Day 
1830 (Visit 41) for participants with a Baseline 
muscle biopsy to obtain longer term information on 
durability of muscle expression and distribution of 
mini-dystrophin
In Section 3.1, added long-term mini-dystrophin 
expression and distribution endpoints to assess 
longer term information on durability of muscle 
expression and distribution of mini-dystrophin
In Section 4.2.4, 2.3.3.2, 4, 5.4, 8.1.3, 1.3.1, and 
SoA, Updated the number of biopsies to be 
collected to approximately 15, with a potential to 
collect a maximum of 33 if needed. Due to 
operational reasons, collection of muscle biopsies in 
approximately 33 participants is not feasible
In Section 4.1, 1.1, and 6.3.1, updated the age caps 
to indicate that no more than approximately 55% of 
dosed participants will be included in either of 
Screening age strata. Additionally, enrollment will 
be assessed periodically, and if an imbalance is 
noted, enrollment of the overrepresented stratum 
may be paused until a more balanced distribution is 
achieved. This change was made to achieve a more 
balanced age distribution in the study so that both 
age strata are equally represented. 
In Section 4.2.4, and 9.5, modified the first interim 
analysis that was to be based on mini-dystrophin 
expression levels as a surrogate endpoint to instead 
occur when approximately 30 participants in the 
FAS complete visits through Week 52 and be based 
on change from Baseline at Week 52 in the NSAA 
total score. Due to operational reasons, an interim 
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analysis based on mini-dystrophin expression levels 
in the first 33 participants is not feasible. These 
updates enable the potential for an earlier regulatory 
submission based on the primary endpoint, NSAA.
In Section 5.1, Appendix 10.14 and Appendix 12, 
Updated exclusion criterion # 15 to also exclude 
patients with a deletion affecting any exon between 
56 and 71, inclusive. Following an SAE of myositis 
reported in this study it was agreed with the E-DMC 
to exclude participants with deletions affecting any 
exon between 56 and 71, inclusive, to prevent 
patients who would be CRIM negative from 
receiving gene therapy, given that they may be at an 
increased risk of immune reactions against the mini-
dystrophin transgene protein expressed in skeletal 
and cardiac muscle.
In Sections 9.1, 9.2, 9.5, and 1.1, Revised the 
approach for controlling Type 1 error to include the 
potential for 2 interim analyses and clarified that a 
gamma family alpha-spending function with gamma 
parameter -1 will be used. Added a futility 
assessment at each interim analysis with gamma 
(-4) spending function. This was done to ensure that 
Type 1 error will be controlled across multiple 
looks at the data and to enable early stopping of 
dosing additional participants for futility
In Appendix 2, and Section 6.5.1, indicated that 
haptoglobin will also be measured at Visit 19 to 
provide a pre-dose value of haptoglobin that would 
help assess changes in haptoglobin that may 
indicate the development on TMA post Year 2 IP 
administration.
New Appendix 12.2, to provide instructions to sites 
for the management of participants retrospectively 
found to meet the updated exclusion criterion # 15, 
depending on their stage of enrolment and their 
treatment cohorts.
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Amendment 11
09 September 
2022
Added Appendix 14: Germany Specific Country 
Amendment 
In Section 10.14.3 added inclusion and exclusion 
criteria from Section 5.1 and 5.2 and added a new 
inclusion criterion (number 9) only for sites in 
Germany: “At the Screening Visit (Visit 1), the 
investigator will discuss and agree with the 
participant or their legally acceptable representative 
the potential need for an autopsy, if the participant 
dies between Year 1 IP administration and during 
the following 10 years”.
Rationale: this inclusion criterion has been added to 
fulfill a request by the German Central Ethics 
Committee.
Added SoA from Section 1.3 to Section 10.14.3 
with additional cardiac troponin I at Week 6 for 
Year 1 and Year 2.
Rationale: these visits and assessments had been 
added to the Germany-specific protocol amendment 
9 to fulfill a request by the German Federal Institute 
for Vaccines and Biomedicines.
Amendment 10
10 June 2022
Country-specific changes as requested by the 
Japan PMDA. 
In Appendix 10, Sections 10.10.1.1 and 10.10.1.2, 
included a new row to display the visits when 
cardiac troponin must be assessed by the local 
laboratory.
Rationale: this change has been made as per the 
request by the Japan PMDA.
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Other updates
In Appendix 2, clarified that for sites in Japan 
GLDH must also be analyzed by the central 
laboratory on Days 2 and 4 (Visits 4 and 5) in 
Year 1, and on Days 391 and 393 (Visit 21 and 
22) in Year 2 even though some of the blood 
tests on these visits are analyzed by the local 
laboratory.
Rationale: correction of an unintentional omission 
in protocol amendment 8.
In Appendix 2 and in Appendix 10, Section 
10.10.1.1, footnote “w” and in Section 
10.10.1.2, footnote “s” clarified that 
haptoglobin, as part of the “Post IP Intensified 
Safety Monitoring (at Year 1 and Year 2)” is 
analyzed by the local laboratory on Days 2 and 
4 (Visits 4 and 5) in Year 1 and on Days 391 
and 393 (Visits 21 and 22) in Year 2 for sites in 
Japan.
Rationale: additional statement for increased clarity.
Amendment 9
13 May 2022
Country-specific changes as requested by the 
German Federal Institute for Vaccines and 
Biomedicines.

In Sections 1.3.1 and 1.3.2 added new visits: 
Visit 13.1, Week 6 at Year 1 and Visit 30.1, 
Week 6 at Year 2 to perform an assessment 
of cardiac troponin-I. Also added footnote to 
indicate that the visit may be performed 
remotely.

Rationale: This change has been 
made as per the request by the 
German Federal Institute for 
Vaccines and Biomedicines.
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Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 05 May 2022.

Sections 1.3.1 and 10.9.1.1, footnotes “e” 
and “f”, and Sections 1.3.2 and 10.9.1.2, 
footnote “b”: removal of instructions for the 
site to communicate with participants via 
email when the study visits are performed 
remotely.
Rationale: It has been determined that email 
communication cannot be used to conduct visits 
since this is not an appropriate method of data 
collection, and should not be used to generate 
source documentation.
Amendment 8 
04 March 2022
Incorporation of country-specific changes 
initially implemented in Germany only via 
Amendment 7, dated 04 March 2022:

In Sections 1.3.1, footnote “d”, 1.3.2, footnote 
“a”, and 8.2.10, added requirement that 
participants will be followed up as inpatients for 
at least 7 days post IP administration. Once 
enrollment is complete and the last participant 
has completed 14 days post-Year 1 IP 
administration, the E-DMC will review the 
safety information accrued to determine if any 
changes to the Year 2 IP administration 
schedule, including need for and length of 
hospitalization, are required. Additionally, in 
Sections 1.3.1, footnotes “d,” “i,” and “j”, 1.3.2, 
footnotes “a,” “h,” and “i,” and 8.2.4, added O2 
saturation and specified vital signs will be 
measured 3 times per day during the inpatient 
stay post IP administration.
Rationale: To optimize follow-up during the 
initial days post-IP administration so that 
any AE is promptly identified and managed. 
This would also allow IV hydration and 
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treatment if there is nausea and/or vomiting 
that may prevent oral intake of 
protocol-mandated glucocorticoid regimen, 
that would decrease the immunosuppression 
that the participant receives and potentially 
increase the risk of immune-mediated AEs.
In Section 8.2.10, updated the list of laboratory 
criteria that would require a participant to return 
to the site within 24 hours to include signs of 
low perfusion volume.
Rationale: To optimize the management of 
participants who may present with signs 
related to a cardiac event by allowing early 
evaluation and management, as needed.
In Sections 1.3.1, 1.3.2, and 8.2.12, added local 
laboratory testing to Baseline (Visit 2), Day 2 
(Visit 4), Day 4 (Visit 5), Days 6, Day 8, and 
Day 10 (Visits 6, 8, and 10) in Year 1, and 
Day 390 (Visit 20) pre-IP administration, 
Day 391 (Visit 21), Day 393 (Visit 22), Day 395 
(Visit 23), Day 397 (Visit 25), and Day 399 
(Visit 27) in Year 2 to assess local cardiac 
troponin I, or cardiac troponin T when cardiac 
troponin I is not available. Also added 
clarification to Section 8.2.12. Local and Central 
Laboratory Testing and Section 10.2, 
Appendix 2: Clinical Laboratory Tests, Table 3. 
Protocol Required Safety Laboratory 
Assessments.
Rationale: Given that local laboratory results are 
available within a few hours after the blood 
extraction, while central laboratory results 
can take up to 4 days to be available, this 
update will optimize the assessment of 
potential cardiac injury by allowing a rapid 
diagnosis and treatment, if required.
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In Sections. 1.3.1, 1.3.2, 8.2.12, and Appendix 2, 
added local serum creatinine testing to Baseline 
Visit (Visit 2), Day 2 and Day 4 (Visits 4 and 5) 
in Year 1, and Days 390 to 393 (Visits 20 to 22 
in Year 2) (local and central laboratory testing).
To provide baseline values in case of 
discrepancy between local and central 
laboratory results.
In Section 5.2, removed the general cardiac criteria 
from exclusion criterion 9 and added new 
cardiac exclusion criteria 16 and 17.
Rationale: An evaluation by a pediatric 
cardiologist is required to ensure that 
participants with clinically relevant cardiac 
pathologies that may increase the risk of 
cardiac complications post receipt of gene 
therapy are not included in the study. To 
ensure that participants who would not be 
candidates for mechanical cardiac or 
respiratory support, or any other invasive 
intervention for diagnosis or management of 
a cardiac SAE, are not included in the study, 
as they would be considered too fragile to be 
suitable for these potentially required 
measures.
In Section 5.2, updated exclusion criterion 14 to 
exclude participants with a LVEF <50%, instead 
of <40%, and to clarify that the screening 
echocardiogram will be evaluated by the central 
reader rather than the site for the purpose of 
determining the LVEF to confirm eligibility.
Rationale: To exclude from the study 
participants who may be at an increased risk 
of cardiac complications, and to ensure 
accuracy and consistency in the assessment 
of LVEF.
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In Section 6.1.1, added ineligibility criterion for 
diagnosis of myocarditis.
Rationale: To ensure that participants with a 
diagnosis of myocarditis that could increase 
the risk of cardiac complications after 
treatment with fordadistrogene 
movaparvovec, are confirmed to be 
ineligible for IP administration.
In Section 7.1, added ineligibility criterion for 
LVEF <50% on echocardiogram performed at 
Day 360 (Visit 19), or at the unplanned visit to 
re-assess eligibility for Year 2 IP administration, 
as evaluated by the central reader. This applies 
only for participants in Cohort 2, confirmed by 
the unblinded medical monitor.
Rationale: To ensure that participants in Cohort 
2 who experience a clinically relevant 
decrease in LVEF that could increase the 
risk of cardiac complications after treatment 
with fordadistrogene movaparvovec, do not 
receive IP (fordadistrogene movaparvovec) 
in Year 2.
In Section 7.1, added ineligibility criterion for 
diagnosis of myocarditis. This applies only for 
participants in Cohort 2, confirmed by the 
unblinded medical monitor.
Rationale: To ensure that participants in Cohort 
2 with a diagnosis of myocarditis that could 
increase the risk of cardiac complications 
after treatment with fordadistrogene 
movaparvovec, do not receive IP 
(fordadistrogene movaparvovec) in Year 2.
In Section 7.1, added ineligibility criterion for a 
participant who is not a candidate for 
mechanical cardiac or respiratory support, or 
any other invasive intervention, if indicated for 
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management of an acute event as determined by 
the cardiologist in consultation with the 
investigator. This applies only for participants in 
Cohort 2, confirmed by the unblinded medical 
monitor.
Rationale: To ensure that participants who are 
not candidates for invasive measures that 
may be required for the treatment of some 
SAEs, for example cardiac SAEs, do not 
receive IP (fordadistrogene movaparvovec) 
in Year 2 as they would be considered too 
fragile to be suitable for these potentially 
required measures.
In Section 8.2.7. Figure 3. Management of Elevated 
Cardiac Troponin I (cTn-I), added new 
instructions for the management of participants 
with elevated levels of cardiac troponin I or T, 
including requirement for echocardiographic 
assessments, assessment of NT-ProBNP/BNP, 
and instructions on when to admit participants 
with elevated cardiac troponin to the hospital, 
even if asymptomatic. Updated the time to 
repeat an elevated cTn-I/ cTn-T from “72-
96 hours” to “approximately 48 to 96 hours”.
Rationale: To improve the ability of the sites 
and the study team to promptly ascertain if 
an elevated cardiac troponin reflects an 
acute cardiac event or if it is related to the 
fluctuations usually seen in patients with 
DMD, to allow for prompt management if 
necessary.
In Section 8.2.10, added a reminder for the 
investigators to discuss with participants and 
caregivers the potential need for participants 
with immune-mediated events to be admitted to 
the intensive care or coronary unit, and to 
require invasive measures such as the placement 
of a central catheter, performance of an 
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endomyocardial biopsy, and use of mechanic 
respiratory or circulatory support.
Rationale: To make participants and caregivers 
aware of the management strategies that 
may be required in cases of immune-
mediated complications, including cardiac 
events.
In Section 1.3.1, removed footnote “e”, and in 
Section 1.3.2, removed footnote “b” due to 
addition of inpatient hospital stay for at least 
7 days post IP administration.
Other changes:
In Sections 1.3.1, footnotes “b” and “f”, 1.3.2, 
footnotes “bb” and “cc”, 5.2, 6.5.1, 6.5.2, 7.1, 
and 8.2.10, provided instructions for the 
management of Cohort 1 and Cohort 2 
participants retrospectively confirmed to meet 
exclusion criterion 15 after the enrollment and 
dosing pause implemented on 04 August 2021.
Rationale: To ensure that participants in Cohort 
1 who had already received fordadistrogene 
movaparvovec and were retrospectively 
found to meet exclusion criterion 15 remain 
in the study for safety monitoring, but do not 
receive placebo in Year 2, given that it also 
requires a regimen of high doses of steroids 
for 3 months and very frequent visits to the 
site with associated laboratory tests.
Rationale: To also ensure that participants in 
Cohort 2 who received placebo in Year 1 
and would receive fordadistrogene 
movaparvovec in Year 2 are withdrawn 
from the study to allow them to pursue other 
treatment(s).
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In Section 1.3.2, increased the visit window for Day 
390 (Visit 20) from ± 2 days to ± 3 days.
Rationale: To give sites additional flexibility for 
Year 2 IP administration.
In Section 5.3.2, added instructions on how to 
manage participants with delayed Year 2 IP 
administration after the enrollment and dosing 
pause implemented on 21 December 2021 is 
lifted.
Rationale: To be able to re-evaluate Year 2 IP 
administration eligibility.
In Section 8.1.3, added statement to consider 
performing a muscle biopsy to aid diagnosis 
and/or management in the event of an SAE 
affecting skeletal and/or cardiac muscle, to 
comply with a commitment made to the French 
regulators, National Agency for the Safety of 
Medicines and Health Products. This update is 
now applied globally.
Rationale: To be able, when possible, to obtain 
relevant information for the diagnosis and 
management of these SAEs.
In Section 5.2, relocated specific criteria for 
retrospective assessment of exclusion criterion 
15 to a newly added Appendix 12.
In Sections 1.3.1, footnote “hh”, and 1.3.2, 
footnote “aa”, added clarification to specify only 
participants with a pre-IP administration cardiac 
MRI will have a follow-up cardiac MRI on 
Day 360 (Visit 19) and on Day 749 (Visit 35).
In Section 6.3.3, removed exclusion criterion 15 as 
it is not sensitive clinical data.
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In Section 8.1.8, clarified that after certification, a 
Rater ID will be provided to each CE. The CE is 
responsible for recording their Rater ID on each 
completed worksheet.
In Section 9.1.1, corrected estimand definitions by 
removing “in all randomized participants”.
Rationale: To align with the previously revised 
definition of the FAS.
In Section 10.9.1, incorporated all changes 
consistent with Sections 1.3.1 and 1.3.2.
Provided clarifying text and corrected typographical 
and grammatical errors where necessary.
Rearranged rows in SoA and reformatted Table 3 in 
Appendix 2 for more clarity.
In Section 5.3.1, modified to specify a second 
unplanned visit will only be needed for 
participants with a positive NAb to AAV9 test 
at the Screening Visits (Visit 1).
Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 24 January 2022:
Modified Section 5.3 heading to “Management of 
Participants Post Enrollment and Dosing Pause” 
and added new subheadings 5.3.1. Study and 
Year 1 IP Administration Eligibility and 5.3.2. 
Year 2 IP Administration Eligibility.
In Sections 1.3.2, footnotes “a” and “q”, 5.3.2, and 
6.5.1, provided instructions on how to manage 
participants with delayed Year 2 IP 
administration during the screening, 
randomization, and dosing pause, implemented 
on 21 December 2021.
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In Section 8.2.7, clarified that given that the central 
laboratory is using a new cardiac troponin assay 
(Beckman) with a different upper limit of 
normal (ULN) than that previously used 
(Centaur), the instructions for further 
assessments of participants with an absolute 
level of cardiac troponin of 1.5 ng/ml are now 
presented as the difference between the present 
value of cardiac troponin and the ULN, and not 
an absolute value. The current criterion is 
equivalent to the previous one, given that the 
absolute number of 1.5 ng/ml is 50X > the ULN 
of the previous assay.
Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 13 January 2022:
In Section 1.3.1 Schedule of Activities Footnote “f” 
Visit 18, Section 4.1 Table 1, Section 6.1.1 
Administration, and Section 6.2.1. Preparation 
and Dispensing, added text to prevent the dose 
of IP being calculated and IP being shipped to 
the site during a study dosing pause, weight will 
not be entered in the interactive response 
technology drug management system during the 
study dosing pause. Once the study is re-started, 
sites will be able to enter an updated weight in 
the interactive response technology drug 
management system to allow the calculation of 
the dose of IP and trigger the shipment of IP to 
the site.
Incorporation of updates made by the Belgium 
Protocol Administrative Changes and 
Clarifications for Study C3391003 letter, dated 
07 December 2021. These updates are now 
applied globally:
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Incorporation of a requirement by MHRA and 
communicated to sites in UK via a Dear 
Investigator Letter dated 07 December 2021. 
These updates are now applied globally:

In Section 9.5.1 Data Monitoring Committee, 
clarified that if the trial is temporarily paused, 
halt notification will be submitted to the 
regulatory authorities within the regulatory 
timelines set in the current applicable 
regulations, and the trial restart will be only 
possible after regulatory approval via a 
substantial amendment if needed.
Incorporation of updates made by the Japan 
Protocol Administrative Changes and 
Clarifications for Study C3391003 letter, dated 
02 November 2021:
Removed Section 10.10.2. Viral Vector Shedding 
Analysis and reference to Section 10.10.2 within 
Section 8.8.5 since it was considered that the 
shedding profile of fordadistrogene movaparvovec 
was clarified in the ongoing Phase 1b study, the 
viral shedding analysis for all Japanese participants 
in accordance with the Cartagena Act Type I use 
regulations is not required, and the provisions of the 
study protocol will be applied to Japanese 
participants.
Amendment 7
04 March 2022
Country-specific changes implemented in 
Germany only:

In Sections 1.3.1, footnote “d”, 1.3.2, footnote 
“a”, and 8.2.10, added requirement that 
participants will be followed up as inpatients for 
at least 7 days post IP administration. Once 
enrollment is complete and the last participant 
has completed 14 days post-Year 1 IP 
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administration, the E-DMC will review the 
safety information accrued to determine if any 
changes to the Year 2 IP administration 
schedule, including need for and length of 
hospitalization, are required. Additionally, in 
Sections 1.3.1, footnotes “d,” “i,” and “j”, 1.3.2, 
footnotes “a,” “h,” and “i,” and 8.2.4, added O2 
saturation and specified vital signs will be 
measured 3 times per day during the inpatient 
stay post IP administration.
Rationale: To optimize follow-up during the 
initial days post-IP administration so that 
any AE is promptly identified and managed. 
This would also allow IV hydration and 
treatment if there is nausea and/or vomiting 
that may prevent oral intake of 
protocol-mandated glucocorticoid regimen, 
that would decrease the immunosuppression 
that the participant receives and potentially 
increase the risk of immune-mediated AEs.
In Section 8.2.10, updated the list of laboratory 
criteria that would require a participant to return 
to the site within 24 hours to include signs of 
low perfusion volume.
Rationale: To optimize the management of 
participants who may present with signs 
related to a cardiac event by allowing early 
evaluation and management, as needed.
In Sections 1.3.1, 1.3.2, and 8.2.12, added local 
laboratory testing to Baseline (Visit 2), Day 2 
(Visit 4), Day 4 (Visit 5), Day 6, Day 8, and 
Day 10 (Visits 6, 8, and 10) in Year 1, and 
Day 390 (Visit 20) pre-IP administration, 
Day 391 (Visit 21), Day 393 (Visit 22), Day 395 
(Visit 23), Day 397 (Visit 25), and Day 399 
(Visit 27) in Year 2 to assess local cardiac 
troponin I, or cardiac troponin T when cardiac 
troponin I is not available. Also added 
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clarification to Section 8.2.12. Local and Central 
Laboratory Testing and Section 10.2, 
Appendix 2: Clinical Laboratory Tests, Table 3. 
Protocol Required Safety Laboratory 
Assessments.
Rationale: Given that local laboratory results are 
available within a few hours after the blood 
extraction, while central laboratory results 
can take up to 4 days to be available, this 
update will optimize the assessment of 
potential cardiac injury by allowing a rapid 
diagnosis and treatment, if required.
In Sections. 1.3.1, 1.3.2, 8.2.12, and Appendix 2, 
added local serum creatinine testing to Baseline 
Visit (Visit 2), Day 2 and Day 4 (Visits 4 and 5) 
in Year 1, and Days 390 to 393 (Visits 20 to 22 
in Year 2) (local and central laboratory testing).
To provide baseline values in case of 
discrepancy between local and central 
laboratory results.
In Section 5.2, removed the general cardiac criteria 
from exclusion criterion 9 and added new 
cardiac exclusion criteria 16 and 17.
Rationale: An evaluation by a pediatric 
cardiologist is required to ensure that 
participants with clinically relevant cardiac 
pathologies that may increase the risk of 
cardiac complications post receipt of gene 
therapy are not included in the study. To 
ensure that participants who would not be 
candidates for mechanical cardiac or 
respiratory support, or any other invasive 
intervention for diagnosis or management of 
a cardiac SAE, are not included in the study, 
as they would be considered too fragile to be 
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suitable for these potentially required 
measures.
In Section 5.2, updated exclusion criterion 14 to 
exclude participants with a LVEF <50%, instead 
of <40%, and to clarify that the screening 
echocardiogram will be evaluated by the central 
reader rather than the site for the purpose of 
determining the LVEF to confirm eligibility.
Rationale: To exclude from the study 
participants who may be at an increased risk 
of cardiac complications, and to ensure 
accuracy and consistency in the assessment 
of LVEF.
In Section 6.1.1, added ineligibility criterion for 
diagnosis of myocarditis.
Rationale: To ensure that participants with a 
diagnosis of myocarditis that could increase 
the risk of cardiac complications after 
treatment with fordadistrogene 
movaparvovec, are confirmed to be 
ineligible for IP administration.
In Section 7.1, added ineligibility criterion for 
LVEF <50% on echocardiogram performed at 
Day 360 (Visit 19), or at the unplanned visit to
re-assess eligibility for Year 2 IP administration, 
as evaluated by the central reader. This applies 
only for participants in Cohort 2, confirmed by 
the unblinded medical monitor.
Rationale: To ensure that participants in Cohort 
2 who experience a clinically relevant 
decrease in LVEF that could increase the 
risk of cardiac complications after treatment 
with fordadistrogene movaparvovec, do not 
receive IP (fordadistrogene movaparvovec) 
in Year 2.
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In Section 7.1, added ineligibility criterion for 
diagnosis of myocarditis. This applies only for 
participants in Cohort 2, confirmed by the 
unblinded medical monitor.
Rationale: To ensure that participants in Cohort 
2 with a diagnosis of myocarditis that could 
increase the risk of cardiac complications 
after treatment with fordadistrogene 
movaparvovec, do not receive IP 
(fordadistrogene movaparvovec) in Year 2.
In Section 7.1, added ineligibility criterion for a 
participant who is not a candidate for 
mechanical cardiac or respiratory support, or 
any other invasive intervention, if indicated for 
management of an acute event as determined by 
the cardiologist in consultation with the 
investigator. This applies only for participants in 
Cohort 2, confirmed by the unblinded medical 
monitor.
Rationale: To ensure that participants who are 
not candidates for invasive measures that 
may be required for the treatment of some 
SAEs, for example cardiac SAEs, do not 
receive IP (fordadistrogene movaparvovec) 
in Year 2 as they would be considered too 
fragile to be suitable for these potentially 
required measures.
In Section 8.2.7. Figure 3. Management of Elevated 
Cardiac Troponin I (cTn-I), added new 
instructions for the management of participants 
with elevated levels of cardiac troponin I or T, 
including requirement for echocardiographic 
assessments, assessment of NT-ProBNP/BNP, 
and instructions on when to admit participants 
with elevated cardiac troponin to the hospital, 
even if asymptomatic. Updated the time to 
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repeat an elevated cTn-I/cTn-T from “72-
96 hours” to “approximately 48 to 96 hours”.
Rationale: To improve the ability of the sites 
and the study team to promptly ascertain if 
an elevated cardiac troponin reflects an 
acute cardiac event or if it is related to the 
fluctuations usually seen in patients with 
DMD, to allow for prompt management if 
necessary.
In Section 8.2.10, added a reminder for the 
investigators to discuss with participants and 
caregivers the potential need for participants 
with immune-mediated events to be admitted to 
the intensive care or coronary unit, and to
require invasive measures such as the placement 
of a central catheter, performance of an 
endomyocardial biopsy, and use of mechanical 
respiratory or circulatory support.
Rationale: To make participants and caregivers 
aware of the management strategies that 
may be required in cases of immune-
mediated complications, including cardiac 
events.
In Section 1.3.1, removed footnote “e”, and in 
Section 1.3.2, removed footnote “b” due to addition 
of inpatient hospital stay for at least 7 days post IP 
administration.
Amendment 6
01 September 
2021
In Sections 1.1, 4.1, 5.4, and 9.2, clarified that the 
study size is now approximately 99 participants in 
the FAS.
To ensure that the study has adequate power for 
the primary endpoint analysis.
In Sections 1.3.1, 1.3.2, 6.3.3, and 10.9.1, added a 
new ADA to mini-dystrophin assessment at Day 14 
in Year 1 and Year 2; and clarification that ADA to 
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mini-dystrophin will be reviewed by the unblinded 
medical monitor on an ongoing basis.
As recommended by the E-DMC to optimize 
safety monitoring.
In Sections 1.3.1, 1.3.2, and 10.9.1, added cardiac 
troponin I assessments to Days 28, 48, 74, and 90 in 
Year 1 and Days 417, 437, 463, and 479 in Year 2 
in the Schedule of Activities. Removed cardiac 
troponin I assessments on Day 7 in Years 1 and 2 in 
the Schedule of Activities due to addition of central 
laboratory assessments on these days in 
Section 10.2 (Appendix 2).
To optimize the monitoring for myocardial 
injury during the period when the risk of 
cellular immune response is anticipated to be 
most likely.
In Sections 1.3.1, 1.3.2, 3.2, and 10.9.1, added 
cardiac MRI assessments to Screening Visit 
(Visit 1) or Baseline (Visit 2) and Week 52 in 
Years 1 and 2, relevant footnotes to Schedule of 
Activities, and associated objectives and endpoints.
To establish presence or absence of cardiac 
injury prior to delivery of gene therapy, and 
to aid in interpretation of cardiac MRI that 
may be performed in response to adverse 
events.
In Sections 1.3.1, 1.3.2, 5.3, 5.6, 7.1, and 10.9.1, 
clarified that participants who exceed the time 
between the Screening Visit (Visit 1) and the Day 1 
Visit (Visit 3), or the time between Day 360 Visit 
(Visit 19) and the planned Day 390 Visit (Visit 20) 
due to operational or administrative reasons 
(eg, enrollment pause due to regulatory or safety 
review, operational issues causing significant 
delays) will not be screen failed/withdrawn from the 
study, but will repeat some tests and assessments to 
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re-confirm study eligibility/IP administration 
eligibility criteria, and to rule out significant 
changes in key tests and assessments.
At the time of the implementation of the 
enrollment/dosing pause, there were 
3 participants who had started the screening 
process, but had not yet been randomized, 
and 12 participants who had been 
randomized, but had not yet received IP. To 
avoid withdrawing participants who may still 
be eligible for study entry, they may be 
re-assessed for study entry at unplanned 
visits. If they still meet study entry criteria, 
they will continue participating; if, following 
the re-assessment, they do not meet study 
entry criteria, they will be screen 
failed/withdrawn.
In Sections 1.3.1, 1.3.2, and 10.9.1, added 
additional measurements of CK at Days 21, 28, 48, 
and 74 at Year 1, and at Days 410, 417, 437, and 
463 at Year 2.
To optimize the monitoring, by the unblinded 
medical monitor, of markers of muscle 
injury, during the period when the risk of 
cellular immune response is anticipated to be 
most likely.
In Sections 1.3.1 (footnote bb.), 5.3 (new), 7.1, and 
10.9.1, clarified that IP administration can only take 
place if there is a NAb to AAV9 test from a sample 
collected 55 days or less before the dosing date.
Given the enrollment/dosing pause, the NAbs to 
AAV9 will be repeated more than once to 
ensure that the last collection has been taken 
no more than 55 days before dosing.
In Section 2.3.2, updated to indicate that cases of 
skeletal muscle and cardiac injury have been 
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observed in clinical studies of fordadistrogene 
movaparvovec.
To inform investigators that the events 
previously described as potential risks have 
now been reported, to increase awareness of 
the need to carefully monitor for these 
events.
Added a new Section 2.3.3.7 Gadolinium to 
describe the risks related to use of gadolinium for 
the cardiac MRI.
In Section 5.2, added clarity to Exclusion 
Criterion 9 that a cardiology consultation should be 
obtained to evaluate any findings on cardiac history 
or imaging to help determine eligibility for the 
study.
To ensure that a participant with a cardiac 
finding during the screening period is 
evaluated by a pediatric cardiologist, and that 
the risk:benefit ratio of enrolling such a 
participant is carefully considered in this 
circumstance.
In Section 5.2, added new exclusion criterion #14
for LVEF <40%. Added clarification to 
Section 8.2.6 to specify LVEF below 50% at any 
visit after screening.
To exclude participants with high cardiac risk.
In Section 5.2, added exclusion criterion 15 for 
participants with specific mutations in the 
dystrophin gene considered to increase the risk of 
immune-mediated adverse reactions.
Recommendation by the E-DMC based on the 
review of the immune and genetic data from 
studies C3391001 and C3391003.
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In Sections 5.2, 6.3.3, and 7.2, added instructions 
for the retrospective assessment of exclusion 
criterion 15.
This key entry criterion must be evaluated for all 
study participants, to help minimize the risk 
of immune-mediated adverse reactions.
In Section 5.2, added “investigational vaccine” to 
“investigational drug” in exclusion criterion 3. This 
change was also applied in Section 6.1.1 #3.
For completion of the exclusion criterion.
Added new Section 5.3 (“Siblings” moved to 
Section 5.4), added list of tests and assessments to 
be repeated in participants who exceed the 90-day 
period between screening and dosing in Year 1, or 
the period between Visit 19 and Visit 20 in Year 2.
Some tests and assessments may have clinically 
significant variations in 90 days, that could 
make a participant previously eligible for 
study/IP administration no longer eligible; 
and/or affect the interpretation of the study.
In Section 8.2.7, amended instructions for actions 
based on tests/evaluations for an elevated cardiac 
troponin I in the troponin algorithm in Figure 3 
Management of Elevated Cardiac Troponin I 
(cTn-I) values to specify the conditions in which a 
cardiac MRI will be performed.
For cTn-I levels and changes that are atypical for 
DMD, a cardiac MRI would be useful in 
determining the nature of the cardiac 
involvement and whether medical 
intervention is warranted.
Added a new Section 8.2.8 Cardiac MRI to include 
instructions on collection of cardiac MRIs.
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In Section 8.2.10, clarified that the redacted medical 
records with the results of the local laboratory tests 
that the sites send to the sponsor must be password 
protected.
To protect the privacy of the study participants.
Added a new Section 8.2.11. Additional Safety 
Monitoring to include monitoring of signs and 
symptoms of cardiac injury.
To optimize the monitoring for cases of muscle 
weakness and/or myocarditis to help early 
detection and management if needed.
In Sections 1.3.1, 1.3.2, 3.1, 8.9, and 10.9.1, added 
Healthcare Resource Utilization Questionnaire –
Caregiver (HRU:CG) and Work Productivity and 
Activity Impairment DMD Questionnaire –
Caregiver (WPAI:DMD Caregiver), and associated 
objectives and endpoints.
To assess the indirect effects that treatment with 
fordadistrogene movaparvovec may have on 
caregivers.
In Sections 1.3.1, 1.3.2, 8.1.7.1.4, and 10.9.1, added 
EQ-5D-5L questionnaire.
To assess the indirect effects that treatment with 
fordadistrogene movaparvovec may have on 
quality of life for caregivers.
In Section 8.3.5.1, specified that pregnancy in a 
female household member of a study participant 
must be reported if the exposure through viral 
shedding occurred within 2 months after the 
participant’s dosing, and a month prior to or during 
pregnancy.
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This is a program level decision based on the 
available data on viral vector shedding from 
the Phase 1 study.
In Section 9.3, revised the definition of the FAS to 
additionally require that participants be dosed with 
IP on Day 1 (Year 1 Day 1) and to specify that 
participants who meet exclusion criterion 15 will be 
excluded. Clarified that participants meeting 
exclusion criterion 15 will be included in the safety 
populations.
To align the analysis populations with the 
revised study population following 
re-evaluation of the participants who were 
randomized but not dosed, at the time of 
implementation of the enrollment and dosing 
pause, and with the addition of exclusion 
criterion 15.
In Section 9.5, added instructions that, in the event 
of a serious safety issue, the sponsor may determine 
that screening, randomization, and/or dosing are 
paused until the E-DMC reviews the relevant data, 
and makes recommendations for the study conduct.
 
 
In Section 10.9 (Appendix 9), correction of blood 
volume values due to re-configuration of testing 
tubes by the central laboratory vendor. It does not 
increase the approximate total volume calculated 
per participant, which was updated in Section 8.
Added new Section 10.12 (Appendix 12) to include 
a description of the general outline of a 
post-approval, long term follow up study.
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Requested by the Italian regulatory authority.
Added new Section 10.13 (Appendix 13) Protocol 
Amendment History to move past amendment 
history from Protocol Amendment Summary of 
Changes Table.
Amendment 5
14 April 2021
In Section 1.3.1, added new row to Schedule of 
Activities to inform caregivers about study 
C3391007 for US sites. Study C3391007 was also 
added to the Section 8.8.6 heading.
In Section 1.3.1, clarified in the Schedule of 
Activities that, when agreed by the site, testing for 
NAb to AAV9 could be done on the first day of 
Screening (Visit 1); and that only participants with a 
negative test for NAb to AAV9 will complete the 
rest of Screening (Visit 1).

To reduce the burden of additional tests and 
assessments for participants who are 
ineligible for study participation.
In Sections 1.3.1 and 1.3.2, added additional visits 
to assess GLDH and chemistry panel to optimize 
the monitoring of hepatic safety in line with the 
product information of Zolgensma.
In Section 2.3.3.1, added text to describe the 
potential risk of adrenal insufficiency during the 
tapering of glucocorticoids for the 
protocol-mandated glucocorticoid regimen.
Added new Section, 2.3.3.6, to describe the risks 
related to sorbitol since each intravenous infusion of 
fordadistrogene movaparvovec (and infusion of 
placebo) contains 5% sorbitol.
In Section 5.2, added a new exclusion criterion for 
participants with known hypersensitivity to any of 
the components of the IP or solution for infusion, 
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such as hypersensitivity to albumin or a diagnosis of 
hereditary fructose intolerance (HFI).

To prevent the enrollment of participants at 
risk of hypersensitivity reactions.
In Section 5.2, added a new exclusion criterion to 
align with the guidance to consider treatment with 
eculizumab.
In Section 5.2, deleted exclusion criterion #8 and 
#9. These therapies (vaccines, except live 
attenuated; interferon; systemic antivirals and 
immunosuppressors) will be prohibited only for 
30 days before Day 1 (Visit 3) and for the first 
2 years of the study. This update is also reflected in 
Sections 6.1.1, 6.5.1, 6.5.2, and 7.1.

To increase flexibility in the administration 
of vaccines and the above-mentioned 
medications, while still ensuring adequate 
time for any effect on the immune system to 
be stabilized before IP administration.
In Section 5.2, updated in exclusion criterion #7 the 
prohibition for receipt of live attenuated vaccines 
from 90 to 30 days before Screening Visit (Visit 1) 
and clarified that these vaccines are prohibited for 
90 days before IP administration. This update is also 
reflected in Sections 6.1.1, 6.5.1, and 7.1.
To increase flexibility in the administration 
of vaccines while still ensuring adequate 
time for any effect on the immune system to 
be stabilized before IP administration.
In Section 5.2, updated exclusionary level of 
cystatin C to >1.2 x ULN. This update is also 
reflected in Sections 6.3.3 and 7.1.
To account for elevated values as a result of 
treatment with steroids, that do not reflect 
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renal impairment, at Screening and at the 
time of evaluation of Year 2 IP 
administration eligibility.
In Section 5.3, clarified that 2 (or more) brothers 
can receive IP at different times as long as the 2 (or 
more) brothers are kept strictly separated from each 
other until all have received IP. This update is also 
reflected in Section 6.3.1.

To allow flexibility in the dosing schedule, 
while still minimizing the risk of 
development of neutralizing antibodies to 
AAV9 in the sibling who has not yet received 
IP.
Updated Section 5.4.2 to indicate that participants 
should be monitored to determine if they pass urine 
at least once during a 12-hour period or if they have 
a significant change in urine output in less than 
24 hours. These updates are also reflected in Section 
8.2.9.

To allow early identification of participants 
with potential kidney injury, and to align 
with the guidance to consider treatment with 
eculizumab.
In Section 6.1.1, added guidance on how to proceed 
when participants have hypersensitivity reactions 
during IP infusion.
In Section 6.2.1, clarified that IP should be 
dispensed once participants have been confirmed to 
be eligible and admitted to the site and added a 
recommendation to prepare IP solution as close to 
the time of dosing as possible.
In Section 6.3.3, clarified that the unblinded 
medically qualified monitor (unblinded medical 
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monitor) will not review the results of ADA and 
ELISpot for each participant on an ongoing basis.

The results of these tests do not have 
identified thresholds to initiate clinical 
actions and are therefore not relevant for 
safety monitoring.
In Section 6.5.1, added an additional step of 
1.5 mg/kg/day of prednisone/prednisolone for 
14 days to the tapering of glucocorticoids during the 
protocol-mandated glucocorticoid regimen, to 
minimize the risk of adrenal insufficiency. The total 
duration of the protocol-mandated glucocorticoid 
regimen is now 90 days. This update is also 
reflected in Sections 1.3.1, 1.3.2, 2.3.2, and 6.1.1.
In Section 6.5.1, clarified that IV glucocorticoids 
can be administered per the clinical judgement of 
the investigator to participants with vomiting.

To ensure that participants with vomiting and 
unable to tolerate oral medications receive 
adequate treatment with glucocorticoids.
In Section 6.5.1, updated prohibition time for live 
attenuated vaccines to no later than 90 days before 
investigational product (IP) administration.

To align with the updated exclusion 
criterion #7.
In Section 6.5.1, updated prohibition time for 
meningococcal vaccine from no later than 2 weeks 
to 30 days before investigational product (IP) 
administration.

To align the time restrictions with other 
inactivated vaccines.
In Section 6.5.1, added guidance on when to 
administer an mRNA, or DNA-based, or 
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non-replicating viral vector vaccine (eg, against 
SARS-CoV-2). This update is also reflected in 
Section 7.1.

To allow participants to receive a vaccine 
against SARS-CoV-2 if indicated, while 
minimizing the potential impact on the safety 
and efficacy of fordadistrogene 
movaparvovec.
In Section 6.5.2, added new text to indicate that 
antiviral therapy and interferon can be administered 
to treat an acute viral infection (eg, COVID-19).
In Section 8.2.9, updated platelet criterion for which 
participants will be required to return to the site for 
evaluation from <100 x 103/µl to <75 x 103/µl.

To align this criterion with the guidance 
provided to consider start of treatment with 
eculizumab.

In Section 8.2.9, added a description of the 
process to review local laboratory reports.
In Section 8.3.1, added language.

To align with new template requirements.
In Sections 8.3.5.1, 8.3.5.2, and 8.3.5.3, updated 
language for Exposure During Pregnancy and 
Occupational Exposure, and added language for 
Exposure During Breastfeeding.

To align with new template requirements.
Added Sections 8.3.7 through 8.3.9.

To align with new template requirements.
In Section 8.3.10, updated time period for 
notification of the Sponsor from immediately to 
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within 24 hours in the event of a medication dosing 
error.

To align with new template requirements.
In Section 8.4, updated overdose language.

To align with new template requirements.
In Section 8.9, removed language that described a 
study to assess caregivers’ burden as it has been 
canceled.
In Sections 10.3.2 and 10.3.3, updated the 
Definition of SAE to include suspected transmission 
via a Pfizer product of an infectious agent, updated 
the Recording/Reporting and Follow-up of AEs 
and/or SAEs to specify all AEs/SAEs associated 
with exposure during pregnancy or breastfeeding be 
recorded on the CRF, and note all SAEs associated 
with exposure during pregnancy or breastfeeding 
and all AEs/SAEs associated with occupational 
exposure should be reported on the CT SAE Report 
Form to Pfizer Safety within 24 hours of awareness.

To align with new template requirements.
Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 16 March 2021:

In Sections 1.3.1 and 1.3.2, added cardiac 
troponin I assessments to Visits 7 and 13 in 
Year 1 and Visits 24 and 30 in Year 2 to 
Schedule of Activities.

Incorporation of updates made by the 
Protocol Administrative Changes and 
Clarifications for Study C3391003 letter, 
dated 19 March 2021:In Section 6.5.1, 
modified the wording to allow investigators 
to change the dose of glucocorticoids at any 
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time, if medically required, and in 
consultation with the Sponsor.

To allow the investigators to change the 
doses of glucocorticoids to treat not only 
an immune reaction, but also other 
medical issues. Additionally, allowing 
these changes at any time, instead of only 
during the first 2 months, would permit 
treatment of late immune reactions, if 
needed.
Incorporation of updates made by the Japan 
Protocol Administrative Changes and Clarifications 
for Study C3391003 letter, dated 14 July 2020:

In Sections 6.1 and 10.10.1, added the 
reporting of Interventional Study Defects 
applicable to Japanese investigators and 
Japanese sites per the Japanese regulation: 
“Act on Securing Quality, Efficacy and 
Safety of Products including Pharmaceuticals 
and Medical Devices.”
Incorporation of updates made by the Japan 
Protocol Administrative Changes and Clarifications 
for Study C3391003 letter, dated 01 September 
2020:

In Sections 8.8.5 and 10.10.2, specified viral 
vector shedding samples for participants 
randomized in Japan will be collected from 
all participants, rather than limiting it to 
approximately 45 initially treated 
participants.
Incorporation of updates made by the Japan 
Protocol Administrative Changes and Clarifications 
for Study C3391003 letter, dated 09 November 
2020:
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
In Sections 1.3.1, 1.3.2, and Appendix 2, 
added new text requested by PMDA to 
indicate blood and urine samples collected at 
Visits 4 and 5 in Year 1 and Visits 21 and 22 
in Year 2 will be sent to the local and central 
laboratory for sites in Japan.

In Sections 4.1 and 10.10.3, added new text 
requested by PMDA to ensure at least 
14 days between IP administration for 
consecutive participants.

In Sections 8.2.9 and 10.10.4, added new text 
agreed upon by PMDA to indicate 
participants randomized from sites in Japan 
will be admitted to hospital for at least 
14 days after IP administration and will be 
discharged if there are no ongoing adverse 
events that require medical management.

Incorporation of updates made by the Japan 
Protocol Administrative Changes and Clarifications 
for Study C3391003 letter, dated 14 December 
2020:

In Sections 8.3.4 and 10.10.5, added new text 
requested by PMDA to specify the sponsor 
will report SAEs that impact study status to 
the Japan sites within approximately 24 hours 
of Pfizer Japan receipt of the report.

In Sections 10.1.1.1 and 10.10.6, added new 
text requested by PMDA to specify 
information regarding any prohibition or 
restriction imposed by an applicable 
regulatory authority in any area of the world, 
or if the investigator is aware of any new 
information that might influence the 
evaluation of the benefits and risks of the 
investigational product, should be shared 
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with Japan sites approximately 24 hours after 
Pfizer Japan is aware of this information.
Inclusion of changes made upon regulatory 
authority request initially implemented via 
Amendments 2, 3, and 4 (listed below; except for 
blood volume to be drawn per visit in Section 10.9. 
Appendix 9. Italy-Specific Country Amendment).
Other minor clarifications:
In Sections 1.1 (Number of Participants) and 9.2, 
updated language to better align the sample size 
estimation with the primary analysis methodology.
In Section 2.2.1, updated with text from the recent 
RMAT.
In Section 6.1.1, clarified that the temporary 
restrictions for receipt of influenza vaccination also 
apply to other inactivated vaccines (eg, influenza, 
meningococcus, pneumococcus, Haemophilus 
influenzae vaccination).
In Section 8, added text to provide guidance to 
investigators on what tests to prioritize at each visit 
when blood collection cannot be completed.
In Section 8.1.1, added new text to indicate the 
assigned master physiotherapist may request 
additional visits to be video recorded and reviewed 
if CE re-training is required for North Star 
Ambulatory Assessment.
In Section 8.1.4, clarified that trained respiratory 
therapists can also perform the respiratory tests, if 
allowed by the Sponsor.
In Appendix 2, added text to provide guidance to 
the study sites to minimize the risk of complication 
due to venipuncture.
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Added Appendix 11 for implementation of 
alternative measures during public emergencies, 
including the COVID-19 pandemic.
Other minor corrections.
Amendment 4
28 December 
2020
Country-specific changes as requested by the 
German Federal Institute for Vaccines and 
Biomedicines.

Additional information to the text describing 
the rationale and the analysis plan for the 
potential interim analyses in Section 9.5.
Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 21 December 2020.

In Section 1.3.1 Addition of a footnote “bb” 
to the NAb to AAV9 test at the Baseline 
Visit (Visit 2) to indicate that the analysis 
and review of NAb to AAV9 from the 
sample drawn at the Baseline Visit (Visit 2) 
will only be required if the time between the 
Screening Visit (Visit 1) and Day 1 (Visit 3) 
is anticipated to be more than 55 days. 
As a result of a reduction in the time to 
deliver Investigational Product (IP) to 
the site, the time between the first test of 
NAb to AAV9 and the day of IP 
administration will be less than initially 
anticipated, up to 90 days, and hence a 
second NAb to AAV9 at the Baseline 
Visit (Visit 2) is not required to confirm 
eligibility for Year 1 IP administration.

Update the footnote “c” in Section 1.3.1, 
corresponding to the Baseline Visit (Visit 2), 
to reflect the reduced time for delivery of 
Investigational Product to the site.
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Amendment 3
24 November 
2020
Country-specific changes as requested by the Italian 
Medicines Agency.

Addition in Appendix 10.9 of a new 
exclusion criterion (#14), for participants 
with known hypersensitivity to any of the 
components of the study drug or solution for 
infusion.

Addition of information on blood volume to 
be drawn per visit in Appendix 10.9.
Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 01 October 2020:

Clarification in Section 5.2, exclusion 
criterion #2 that patients receiving benefit 
from an ongoing treatment designed to 
increase dystrophin expression should not 
discontinue it in order to enroll in the study. 
Additionally, the time during which any 
treatment designed to increase dystrophin 
expression is prohibited has been changed 
from the first 2 years of the study to the first 
52 weeks of the study. This change was 
already incorporated in the UK-specific 
Amendment 2. 

Clarification in exclusion criterion #10, 
Section 5.2, that one of the hematological 
abnormalities mentioned consists of a platelet 
level <150 x103/µl. This change also applies 
to Section 6.3.3 and Section 7.1. This change 
was already incorporated in the UK-specific 
Amendment 2.

Clarification, in Section 8.2.9 that sites will 
not be made aware of the results of C3 and 
C4 on a routine basis and, in consequence, 
reduced complement levels will not be a 
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criterion for expedited participant evaluation 
at the site within 24 hours.
Knowledge of the levels of C3 and/or C4 is 
not considered necessary for clinical 
decision making. The unblinded medical 
monitor will not share those results 
routinely with the sites and the sponsor 
unless, in their clinical judgement, a 
significant or unexpected abnormality 
should be communicated.

Clarification in Section 8.1.3 that biceps 
brachii muscle biopsies will be collected in 
approximately the first 33 participants 
randomized into Cohorts 1 and 2 (and their 
siblings) from sites that have been trained 
and certified by the Sponsor/Sponsor 
designee to collect open muscle biopsies in 
this study. This update is also reflected in 
Section 1.3.1, footnote “n” and in
Section 2.3.3.2.
It was initially anticipated that sites in the 
United States would be activated first 
and would randomize the first 
approximately 33 participants who must 
have a biceps brachii biopsy collected, as 
per the protocol. Therefore, training and 
certification by the Sponsor/Sponsor 
designee to collect open muscle biopsies 
was planned in advance for these sites. 
Due to unforeseen circumstances, the 
activation of sites in the United States 
has been delayed and therefore sites in 
other countries will be trained to collect 
biceps brachii biopsies.

Addition of details about the flushing of the 
IV line after IP administration in 
Section 6.1.1.
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Important information for the completion of 
IP administration.

Correction of an unintentional mistake in 
Section 6.5.2 that states that systemic 
antiviral and/or interferon therapy will be 
prohibited from the time of signing the 
informed consent until the end of Year 2. The 
instructions should indicate that after Year 1 
Investigational Product administration, the 
use of systemic antiviral and/or interferon 
therapy is only prohibited within 30 days 
prior to Year 2 IP administration, and for the 
first 2 months after each IP administration. 
The corrected text in Section 6.5.2 is in 
alignment with the text in exclusion criterion 
#8, Section 5.2.

Correction in Section 8.4 of the text about 
overdose to clarify that for this study, any 
dose of fordadistrogene movaparvovec 
greater than a single administration of 2E14 
vg/kg will be considered an overdose, even if 
it occurs outside of a 24 hour time period.

In Section 8.1.4 change the formula to 
calculate %pFVC from Hankinson et al., 
1999 to Qanjer et al., 2012. 
The updated equation is better suited to 
North and East Asian populations that 
will be included in the study.
Amendment 2
05 October 2020
Country-specific changes as requested by the UK 
Medicines and Healthcare products Regulatory 
Agency.
Clarified in Section 5.2, criterion 2, that stopping a 
therapy to increase dystrophin expression in a 
patient who benefits from it, in order to enter the 
study, is not recommended.
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
To stress that decisions and actions regarding 
medication choice must be made by each 
patient and family in consultation with their 
physician with the best interest of the patient 
in mind. 
Clarified in Section 5.2, criterion 10 and in Section 
7.1, criterion 2, that a platelet level <150 x103/µl 
is part of the hematological abnormalities 
mentioned.

Given the observation of reductions in 
platelet levels following administration of 
gene therapy in study C3391001, to reduce 
the risk that a decrease in platelet count 
reaches levels that pose a risk to the 
participant. 
Clarified in Section 5.2 and in Section 6.5.2 that the 
use of a therapy to increase dystrophin 
expression will be prohibited only during the 
first 52 weeks of the study.

To allow a robust primary analysis without 
confounding factors, while at the same time 
give participants the opportunity to start a 
therapy designed to increase dystrophin 
expression, if considered necessary, after Day 
360 (Visit 19).
Incorporation of updates made by the Protocol 
Administrative Changes and Clarifications for 
Study C3391003 letter, dated 17 June 2020:
Removed the requirement to perform the 
post-baseline muscle biopsy at Day 60 
(Visit 14).

Upon review of relevant data from the 
ongoing Phase 1b study, C3391001, it was 
determined that 1 year was the best timing 
for the post-baseline biopsy to be able to 
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demonstrate durability of the effect of gene 
therapy on mini-dystrophin expression.
Removed the allowance to perform a needle biopsy.

Upon discussion with relevant experts, it has 
been confirmed that performing an open 
muscle biopsy is a safe and well tolerated 
procedure and is preferable for ensuring a 
consistent and high quality sample.
Added in Section 6.3.3 a statement to request that 
clinical evaluators who perform and score the 
NSAA should not have access to the 
participant´s medical records and/or to the 
database.

Knowledge of the occurrence of certain 
AEs/SAEs and/or laboratory changes could 
lead to the functional unblinding of the 
clinical evaluators and it could bias the 
scoring of the functional assessments that 
they perform.
Added in Section 6.3.3- Select safety and 
immunogenicity results- a sentence to the 
paragraph relating to a situation when a 
participant in Cohort 2 presents with a positive 
test for NAb to AAV9 at Day 34 (Visit 13): “If 
this situation occurs while the study is still 
accruing participants, an additional 
2 participants may be randomized for each 
Cohort 2 participant who is withdrawn.”

It is expected that it will be extremely rare for 
a participant in Cohort 2 to test positive for 
NAb to AAV9 at Day 34; however, to 
account for the potential for missing data 
specifically for Cohort 2 participants, beyond 
the 10% dropout already assumed for the 
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study, additional participants may be 
randomized.
Section 8.1.6: Changed one part of the definition of 
loss of ambulation after Screening (Visit 1), to 
be evaluated by the walk item in the NSAA 
rather than by the 10 meter run/walk item.

The incorrect NSAA item to determine loss 
of ambulation had been selected given that a 
score of 0 in the 10 meter run item can be 
given to a child who is still able to walk.
Removed the following language in Section 8.2.8: 
“If laboratory values from non-protocol 
specified laboratory assessments performed at 
the institution’s local laboratory require a 
change in participant management or are 
considered clinically significant by the 
Investigator (eg, SAE or AE), then the results 
must be recorded in the CRF”.

To align the protocol with the CRF and the 
CRF completion guidelines.
Replaced the following language in Section 8.3.1.2: 
“Medical occurrences that begin before the start 
of study intervention but after obtaining 
informed consent will be recorded on the 
Medical History/Current Medical Conditions 
section of the case report form (CRF), not the 
AE section” by the updated language: “All 
nonserious AEs and SAEs occurring in a 
participant during the active collection period, 
which begins after obtaining informed consent 
as described in Section 8.3.1, will be recorded 
on the AE section of the CRF”.

To align the protocol with the CRF and the 
CRF completion guidelines.
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Corrected typographical mistakes and added 
clarifying text when needed.
Amendment 1
18 March 2020
Added physical examination to Day 2 Visit in 
Year 1 and Year 2.
Added urinalysis to Day 4, Day 14 and Day 34/Day 
430 Visits.

For safety monitoring.
Added daily visits at Days 6-10 to perform local 
laboratory testing and also central laboratory 
testing of some parameters to prevent sharing 
the results of sensitive clinical data.

To allow a rapid screening for signs of 
development of atypical hemolytic uremic 
syndrome (aHUS).
Re-arranged laboratory tests performed during the 
first two weeks of the study to allow the 
addition of the local laboratory testing without 
exceeding the blood volume limits.
Added 6-month visits during the long-term follow-
up period, Years 3-6 were initially annual visits.

To facilitate retention and align with clinical 
practice.
Updated the safety data from study C3391001.
Added risk potentially associated with the human 
albumin used in the preparation of the IP 
solution.
Changed the description of the dose from 3E14 to 
2E14 and provided an explanation based on a 
new titer assay method.
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
To clarify the change in nomenclature and 
describe the reason that the 3E14 dose used 
in the Phase 1b study is approximately 
equivalent to the 2E14 dose used in Study 
C3391003.
Changed the endpoints for time to run/walk 
10 meters and time to rise from floor to 
10-meter run/walk velocity and rise from floor 
velocity, respectively.

To appropriately include participants in the 
analysis who are not able to perform the 
activity and can be assigned a value of zero 
velocity.
Added efficacy endpoints to assess participants in 
Cohort 2 after receiving fordadistrogene 
movaparvovec through Year 2 Week 52 and 
added efficacy endpoints to assess long-term 
efficacy.

To align the endpoints with those for the 
primary analysis through Week 52.
Added endpoint of ankle range of motion 
assessment.

A clinically meaningful measure that may 
reflect an additional outcome of treatment.
Changed the approach to control the Type I error for 
select secondary endpoints from the Hochberg 
method to a fixed-sequence.

To employ an approach that orders the
endpoints by clinical relevance rather than by 
p-values.
Added peak FVC as an exploratory endpoint.
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
Achieving a larger absolute FVC has been 
shown to be associated with a slower rate of 
decline in respiratory function in boys with 
DMD.
Removed DXA scans and associated endpoints.

Bone mineral density and muscle mass are 
unlikely to change and are difficult to 
interpret in this age range.
Removed WPAI and HRU questionnaires from the 
list of endpoints.
Added a description of the approach to control the 
rate of randomization to be implemented during 
the initial weeks of the study.

To help the understanding and management 
of potential safety risks.
Added a provision for eligible siblings to receive 
same treatment within the study as the 
randomized subject.

To assist with family dynamics when more 
than one sibling is eligible for the study and 
to help prevent seroconversion, and 
subsequent ineligibility for treatment, of a 
sibling if randomized to a different cohort.
Change minimum dose requirement for deflazacort
for inclusion in the study from 0.5 mg/kg to 
0.75 mg/kg.

To account for the different steroid potency 
of deflazacort compared to prednisone and 
prednisolone.
Added inclusion criterion of a minimum NSAA 
total score (NSAA >16 points). 
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
There is already a maximum (NSAA 
<30 points) to avoid a ceiling effect. The 
added minimum score is to mitigate the risk 
of young patients with low scores who could 
have large gains (eg, >10 points) due 
primarily to cognitive/developmental 
changes.
Added inclusion criterion: “Participants/legally 
acceptable representatives who are willing to 
protect the integrity of the study data by not 
actively seeking sensitive clinical data (eg, CK, 
AST, ALT, C3, C4, NAb to AAV9) through 
independent laboratory tests and by not sharing 
trial experiences with other participants or 
publicly (eg, through social media).”

To minimize the potential for functional 
unblinding of participants.
Provided additional information on IP stability in 
cases of interruption of infusion.
Renamed Section 6.3.3 as Clinical Sensitive Data 
(previously named Blinding of Laboratory 
Results) and updated the language in that 
section to align with the Blinding Plan 
Document.
Increased the dose of IV methylprednisolone on 
Day 1 from 1 mg/kg to 2 mg/kg; and increased 
the dose of oral prednisone/prednisolone from 
Days 1 to 15 post-IP administration from 
1 mg/kg to 2 mg/kg. This change applies to 
Year 1 and Year 2.

To increase immunosuppression periIP 
administration to help reduce the risk of 
immune-mediated AEs.
Added provision to temporally increase the daily 
dose glucocorticoids within the first 2 months 
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post IP administration, if necessary to treat an 
immune response. 

To ensure participants´ safety.
Allowed other oral anti-emetics apart from 
ondansetron.
Clarified that the local label and any specific 
requirement must be followed in participant´s 
receiving eculizumab.

To comply with local requirements.
Provided more specific guidance to start treatment 
with eculizumab.

To ensure participants´ safety and harmonize 
the management of cases compatible with 
thrombotic microangiopathy in the study.
Added a requirement that participants who 
experience an event compatible with aHUS will 
be screened for a genetic predisposition to 
aHUS.

To obtain information that may contribute to 
an understanding of the risk for developing 
aHUS.
Changed requirement that participants who receive 
gene therapy other than IP after Year 1 IP 
administration will be withdrawn from the 
study; those participants will not be withdrawn 
from the study.
Updated total blood sampling volume for individual 
participants.
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Deleted recommendation to perform post-Baseline 
muscle biopsy in the same arm than the Baseline 
muscle biopsy.

To align with procedures used in the 
Phase 1b C3391001 study.
Added video recording during NSAA, ankle range 
of motion and FVC assessments.

To enable quality control of NSAA, ankle 
range of motion and FVC assessments.
Limited assessment of FVC to participants 6 years 
or older at Screening and changed the endpoint 
of change from Baseline in %pFVC from 
secondary to exploratory.

Evaluating FVC in participants younger than 
6 years is difficult and unreliable and an 
effect of treatment is unlikely to be observed 
at Week 52 since untreated patients are 
expected to have little/no change in this age 
range.
Updated location of the description of Ambulatory 
Assessment Algorithm, it will be placed in the 
QoL & ADL Manual and not in the Functional 
Assessment Manual.
Added a new Section to provide guidance on the 
management of elevated cardiac troponin-I 
(cTnI) values.

Clinical experience and literature are limited 
relative to the management of cTnI in the 
setting of DMD; guidance based on a prior 
Pfizer interventional study of 121 DMD 
participants is provided.
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Added viral vector shedding sample collection for a 
subset of participants.

To support clinical trial applications and 
Environment Risk assessments in the 
European Union and Japan, and regulatory 
filings in all regions.
Added a new Section to describe the Household 
Immunogenicity study.

To obtain information on the potential and 
timing for household contacts, including 
siblings, to become NAb positive following 
treatment with gene therapy of a family 
member.
Added a description of the analysis approach for the 
skills-based endpoints.

To enable a greater understanding of how 
these endpoints will be evaluated and 
interpreted.
Adapted “Appendix 7: ECG findings” to reflect 
pediatric participants.

To align definitions of AEs noted by ECG 
findings with pediatric values.
Provided additional instructional text where 
necessary.
Provided clarifying text where necessary.
Corrected typographical and grammatical errors.
Updated SOA to reflect corrections, changes and 
updates to assessments.
Original 
protocol
22 May 2019
Not applicable (N/A) 
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10.18. Appendix 18: Abbreviations
The following is a list of abbreviations that may be used in the protocol. 
Abbreviation
Term
DG
-dystroglycan
DG
-dystroglycan
aHUS
Atypical hemolytic uremic syndrome
AAV
adeno-associated virus
AAV9
adeno-associated virus serotype 9
Abs
Absolute
ADA
antidrug antibodies
ADL
activities of daily living
AE
adverse event
ALT
alanine aminotransferase
ANSM
National Agency for the Safety of Medicines and Health Products
AST
aspartate aminotransferase
AxMPs
auxiliary medicinal product
AV
Atrioventricular
BBS
Biospecimen Banking System
BMD
Becker muscular dystrophy
BNP
B-type natriuretic peptide
BP
blood pressure
bpm
beats per minute
BUN
blood urea nitrogen
CBCL
Child Behavior Check List
CE
clinical evaluator
CFR
Code of Federal Regulations
CGIS
Clinician Global Impression of Severity
CIOMS
Council for International Organizations of Medical Sciences
CK
creatine kinase
CO2
carbon dioxide (bicarbonate)
COA
clinical outcomes assessments
CONSORT
Consolidated Standards of Reporting Trials
COVID-19
coronavirus disease 2019
CRF
case report form
CRIM
cross-reactive immune material
CRO
contract research organization
CSR
clinical study report
CT
clinical trial
CTIS
Clinical Trial Information System
cTn-I
cardiac troponin I
cTn-T
cardiac troponin T
DCT
data collection tool
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Abbreviation
Term
DGC
dystrophin-associated glycoprotein complex
DILI
drug-induced liver injury
DMC
data monitoring committee
DMD
Duchenne muscular dystrophy
DNA
deoxyribonucleic acid
DRE
disease-related event
EC
ethics committee
ECG
electrocardiogram
eCRF
electronic case report form
E-DMC
external data monitoring committee 
EDB
exposure during breastfeeding
EDP
exposure during pregnancy
ELISpot
Enzyme-Linked ImmunoSpot
EMA
European Medicines Agency
EQ-5D-5L
EuroQol 5 Dimension 5 Level
EQ-5D-Y
EuroQol 5 Dimensions–Youth
EU
European Union
EudraCT
European Clinical Trials Database
FAS
full analysis set
FAMPH
Federal Agency for Medicines and Health Products
FDA
Food and Drug Administration
FVC
Forced Vital Capacity
GCP
Good Clinical Practice
GGT
gamma-glutamyl transferase
GLDH
glutamate dehydrogenase
HAV
Hepatitis A virus
HBsAg 
hepatitis B surface antigen
HCVAb
hepatitis C antibody
HIPAA
Health Insurance Portability and Accountability Act
HFI
Hereditary Fructose Intolerance
HRU:CG
Healthcare Resource Utilization Questionnaire – Caregiver
IB
Investigator’s brochure
ICD
informed consent document
ICH
International Council for Harmonisation
ID
Identification
IMP
investigational medicinal product
IND
investigational new drug application
INR
international normalized ratio
IP
investigational product
IRB
institutional review board
IRT
interactive response technology
ITR
Inverted terminal repeats
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Abbreviation
Term
IV
intravenous
LC-MS
liquid chromatography mass spectrometry
LFT
liver function test
LGE
late gadolinium enhancement
LVEF
left ventricular ejection fraction
MenACWY
meningococcal conjugate
MenB
serogroup B meningococcal
MHP
mental health providers
MRI
magnetic resonance imaging
mRNA
messenger ribonucleic acid
msec
Millisecond
N/A
not applicable
NAb
neutralizing antibodies
NIMP
noninvestigational medicinal product
NOAEL
No Observed Adverse Effect Level
NSAA
North Star Ambulatory Assessment
NT-ProBNP
N-terminal-pro hormone B-type natriuretic peptide
O2
oxygen
OR
Odds ratio
PACL
protocol administrative change letter
PA
protocol amendment
PASS
post-authorization safety study
PCD
primary completion date
pFVC
Predicted Force Vital Capacity
PGIS:CG
Patient Global Impression of Severity
PI
principal Investigator
PK
pharmacokinetic(s)
PMDA
Pharmaceuticals and Medical Devices Agency 
PODCI
Pediatric Outcomes Data Collection Instrument
PT
prothrombin time
PVC
premature ventricular contraction/complex
QoL
quality of life
qPCR
quantitative Polymerase Chain Reaction 
QTc
corrected QT
QTcF
corrected QT (Fridericia method)
rAAV
Recombinant adeno-associated virus
RBC
red blood cell
RNA
ribonucleic acid
ROM
range of motion
SAE
serious adverse event
SAP
statistical analysis plan
SARS-CoV2
severe acute respiratory syndrome coronavirus 2
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Abbreviation
Term
SD
standard deviation
SmPC
Summary of Product Characteristics
SoA
schedule of activities
SOP
standard operating procedure
SRSD
single reference safety document
SUSAR
suspected unexpected serious adverse reaction
TBili
total bilirubin
TEAE
treatment-emergent adverse event
TG
transgene
ULN
upper limit of normal
US
United States
VAS
visual analog scale
WPAI:DMD 
Caregiver
Work Productivity and Activity Impairment DMD Questionnaire –
Caregiver
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