A Phase 3 Multinational, Randomized, Double-Blind, Placebo-Controlled Systemic Gene Delivery Study to Evaluate the Safety and Efficacy of SRP-9001 in Subjects With Duchenne Muscular Dystrophy (EMBARK)
Phase: PHASE3
Conditions: Duchenne Muscular Dystrophy
Sponsor: Sarepta Therapeutics, Inc.

Delandistrogene moxeparvovec (SRP-9001) 
Protocol  
SRP-9001-301 (Version 5.0, Amendment 4.0) 
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CONFIDENTIAL 
 
 
 
 
CLINICAL STUDY PROTOCOL 
Study Title: 
A Phase 3 Multinational, Randomized, Double-Blind, 
Placebo-Controlled Systemic Gene Delivery Study to 
Evaluate the Safety and Efficacy of SRP-9001 in Subjects 
With Duchenne Muscular Dystrophy (EMBARK) 
Study Number: 
SRP-9001-301 
Version Number, Amendment 
Number: 
Version 5.0, Amendment 4.0 
Compound Number and 
Name: 
Delandistrogene moxeparvovec (also known as SRP-9001)  
Study Phase: 
3 
Coordinating Investigator: 
 
Sponsor Name: 
Sarepta Therapeutics, Inc. 
Legal Registered Address and 
Phone Number: 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
FDA IND Number:  
17763 
EUDRACT or EU CTR 
Number: 
2019-003374-91 
Approval Date: 
28-MAY-2024 
 
CONFIDENTIALITY STATEMENT 
The information contained in this document is the property of the Sponsor and is confidential. 
This information may not be disclosed, reproduced, or distributed to anyone other than 
personnel directly involved in the conduct of the study and in response to a relevant 
Institutional Review Board/Independent Ethics Committee and review by a regulatory 
authority, as required by the applicable laws and regulations, without the written authorization 
of the Sponsor, except to the extent necessary to obtain informed consent/assent from those 
individuals who enroll in this study. These restrictions will continue to apply after the study 
has closed. 
 
PPD
NCT05096221

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SIGNATURE PAGE FOR SPONSOR 
Protocol Title:  
A Phase 3 Multinational, Randomized, Double-Blind, 
Placebo-Controlled Systemic Gene Delivery Study to Evaluate the 
Safety and Efficacy of SRP-9001 in Subjects With Duchenne 
Muscular Dystrophy (EMBARK) 
Study No:  
SRP-9001-301 
This study protocol was subject to critical review and has been approved by the appropriate 
protocol review committee of the Sponsor.  
• The information contained in this protocol is consistent with the current benefit-risk 
evaluation of the investigational product. 
• The clinical study will be conducted in compliance with the protocol, ethical and 
scientific principles governing clinical research as set out in the Declaration of 
Helsinki, Good Clinical Practice (GCP) Guidelines described in the International 
Council for Harmonisation (ICH) E6 (R2) and 21 Code of Federal Regulations, and 
applicable national regulations and directives including the European Union (EU) 
Clinical Practice Directive 2005/28/EC, EU No 536/2014, and Japanese GCP 
Regulation. 
This document was e-signed; the e-signature manifest can be found on the last page. 
 
 
 
 
 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
 
Date 
 
 
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INVESTIGATOR’S AGREEMENT 
I have read and understood all sections of the study protocol SRP-9001-301, Version 5.0, 
Amendment 4.0 dated 28-MAY-2024 entitled “A Phase 3 Multinational, Randomized, 
Double-Blind, Placebo-Controlled Systemic Gene Delivery Study to Evaluate the Safety and 
Efficacy of SRP-9001 in Subjects With Duchenne Muscular Dystrophy (EMBARK)” and the 
accompanying Investigator’s Brochure.  
I agree to supervise all aspects of the protocol and to conduct the clinical investigation in 
accordance with the protocol, the Good Clinical Practice (GCP) described in the International 
Council for Harmonization tripartite guideline E6 (R2) and in 21 Code of Federal Regulations 
(CFR) parts 50, 54, 56, and 312, applicable national regulations and directives such as the 
European Union (EU) Clinical Practice Directive 2005/28/EC, EU No 536/2014, Japanese GCP 
Regulation, and all applicable regulations, directives, and relevant parts of 21 CFR 812; relevant 
Sponsor policies, and conditions of approval by local requirements and regulations. I will not 
make changes to the protocol before consulting with Sarepta Therapeutics or implement protocol 
changes without Institutional Review Board/Independent Ethics Committee approval except to 
eliminate an immediate risk to subjects. I agree to administer study drug only to subjects under 
my personal supervision or the supervision of a delegated sub-investigator. 
I will not supply the investigational drug to any person not authorized to receive it. I agree to 
maintain the confidentiality of all information received or developed in connection with this 
protocol. Subject identity will not be disclosed to third parties or appear in any study reports or 
publications.  
I will not disclose information regarding this clinical investigation or publish results of the 
investigation without authorization from Sarepta Therapeutics.  
 
 
Printed Name of Investigator 
 
Signature of Investigator 
 
Date (DD-MMM-YYYY) 
 

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2. 
PROTOCOL SUMMARY 
2.1. 
Synopsis 
NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
Title of Study: A Phase 3 Multinational, Randomized, Double-Blind, Placebo-Controlled Systemic 
Gene Delivery Study to Evaluate the Safety and Efficacy of SRP-9001 in Subjects With Duchenne 
Muscular Dystrophy (EMBARK) 
Study Number: SRP-9001-301 
Number of Study Sites: This is a multinational clinical study, to be conducted at approximately 
40 sites. 
Phase of Development: Phase 3 
Indication: Duchenne muscular dystrophy (DMD) 
Rationale : Duchenne muscular dystrophy is a rare, serious, debilitating, and ultimately fatal disease 
for which there is an urgent need to develop safe and effective therapies. To meet this urgency and the 
needs of the patient community, this study evaluates the effect of delandistrogene moxeparvovec (also 
known as SRP-9001) compared with placebo in subjects with DMD. Gene replacement therapy has 
been studied for the past 10 to 15 years and shows favorable results in nonclinical studies in species 
deficient in dystrophin. The goal of delandistrogene moxeparvovec therapy is to induce the expression 
of the delandistrogene moxeparvovec dystrophin protein in skeletal and cardiac muscle in order to 
increase strength and protect from contraction-induced injury. Correction of the underlying genetic 
defect in DMD using gene replacement with delandistrogene moxeparvovec is a promising treatment. 
Objectives and Endpoints: 
Objectives 
Endpoints 
Primary 
• To evaluate the effect of delandistrogene 
moxeparvovec on physical function as 
assessed by the North Star Ambulatory 
Assessment (NSAA) score 
• Change in NSAA total score from Baseline 
to Week 52 (Part 1) 
Secondary 
• To evaluate the effect of delandistrogene 
moxeparvovec on physical function as 
assessed by: 
− 
Number of skills gained or improved on 
the NSAA 
 
• Number of skills gained or improved at 
Week 52 (Part 1) as measured by the NSAA 

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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
• To evaluate delandistrogene moxeparvovec 
dystrophin expression from delandistrogene 
moxeparvovec at 12 weeks (Part 1) as 
measured by western blot of biopsied muscle 
tissue 
• Quantity of delandistrogene moxeparvovec 
dystrophin protein expression at Week 12 
(Part 1) as measured by western blot 
• To evaluate the effect of delandistrogene 
moxeparvovec on timed function tests as 
assessed by measuring: 
− 
Time to rise from the floor  
− 
100-meter walk/run (100MWR)  
− 
Time to ascend 4 steps  
− 
10-meter walk/run (10MWR) 
• Change in time to rise from the floor from 
Baseline to Week 52 (Part 1)  
• Change in time of 100MWR from Baseline 
to Week 52 (Part 1) 
• Change in time to ascend 4 steps from 
Baseline to Week 52 (Part 1) 
• Change in time of 10MWR from Baseline to 
Week 52 (Part 1) 
• To evaluate the effect of delandistrogene 
moxeparvovec on stride velocity 95th centile 
(SV95C) as measured by a wearable device 
• Change in SV95C from Baseline to 
Week 52 (Part 1) 
• To evaluate subject (parent/caregiver proxy) 
reported Mobility and Upper Extremity 
Function using the Patient Reported Outcomes 
Measurement Information System (PROMIS®) 
tool 
• Change in PROMIS score in Mobility and 
Upper Extremity from Baseline to Week 52 
(Part 1) 
• To evaluate the safety of delandistrogene 
moxeparvovec 
• Incidence of treatment-emergent adverse 
events 
• Incidence of serious adverse events  
• Incidence of adverse events of special 
interest  
• Clinically significant changes in vital signs 
and physical examination findings 
• Clinically significant changes in safety 
laboratory assessments, electrocardiograms 
(ECGs), and echocardiograms (ECHOs) 
 

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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
Methodology: 
This is a randomized, double-blind, placebo-controlled 2-part study of systemic gene delivery of 
delandistrogene moxeparvovec in approximately 120 male DMD ambulatory subjects ≥ 4 to < 8 years 
of age. Randomization will be stratified 
 
 
. All patients will 
have the opportunity to receive intravenous (IV) delandistrogene moxeparvovec (1.33 × 1014 vg/kg) in 
either Part 1 or Part 2. The study will consist of 4 periods as follows: 
• 
A Screening Period (pre-infusion) which begins a maximum of 31 days prior to the Day 1 
infusion and during which disease characteristics and baseline therapy will be assessed, and 
the pre-infusion evaluation will be completed.  
• 
A Baseline Period (pre-infusion) which begins when eligibility is confirmed and ends on the 
day prior to the Day 1 infusion during which baseline assessments will be completed. 
• 
An Infusion Period during which a single IV infusion of blinded delandistrogene 
moxeparvovec or placebo will be administered within 31 days of obtaining the rAAVrh74 
enzyme-linked immunosorbent assay (ELISA) sample. Approximately 60 subjects will receive 
IV delandistrogene moxeparvovec (1.33 × 1014 vg/kg) and approximately 60 subjects will 
receive placebo (saline, 0.9% sodium chloride solution) in the Infusion Period in Part 1. In the 
Infusion Period in Part 2, subjects who received placebo in Part 1 will receive IV 
delandistrogene moxeparvovec, and subjects who received delandistrogene moxeparvovec in 
Part 1 will receive placebo. All subjects, parents/caregivers, Investigators, and site staff, with 
the exception of the unblinded site pharmacist, will be blinded to subject treatment 
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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
(delandistrogene moxeparvovec or placebo). Refer to the study blinding plan for additional 
details. Starting the day prior to the infusion, all subjects will receive additional glucocorticoid 
(prednisone equivalent) for at least 60 days. 
• 
A 104-week Follow-up Period (post Part 1 infusion) during which safety and efficacy 
parameters will be evaluated in Part 1 and Part 2. Subjects will be expected to attend both 
remote and in-person visits to complete required procedures/assessments. Additional 
unscheduled visits are allowed per the Investigator’s clinical judgement. For subjects who 
complete the study, the last study visit will occur at Part 2 Week 52. For subjects who 
prematurely discontinue post-infusion follow-up, an end of study/early termination visit will 
be required; however, each subject should be strongly encouraged to continue study follow-up 
until 52 weeks post each infusion. 
Efficacy assessments will include the following: 
• 
NSAA 
• 
Time to rise from the floor  
• 
100MWR  
• 
Time to ascend 4 steps 
• 
10MWR 
• 
Real-world stride velocity, 
 
 as assessed by a wearable device 
• 
Muscle biopsy in a subset of subjects 
• 
PROMIS in a subset of subjects 
 
 
 
 
 
Safety assessments will include the following: 
• 
Adverse events 
• 
Vital signs 
• 
Physical examination 
• 
ECGs 
• 
ECHOs 
• 
Laboratory tests 
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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
 
 
 
 
 
After completion of the Part 2 Week 52 assessments, subjects will be eligible to enroll into an 
extension study to assess long-term safety and efficacy. All subjects will be followed for long-term 
safety and efficacy in the extension study for at least 5 years after delandistrogene moxeparvovec 
infusion. 
Number of Subjects (Planned): Approximately 120 subjects will be enrolled in this study. 
MAIN INCLUSION AND EXCLUSION CRITERIA: 
Inclusion Criteria: 
A subject must meet all of the following criteria to be eligible to participate in this study: 
1. Is male at birth, ambulatory, and ≥ 4 to < 8 years of age at the time of randomization. 
2. Has a definitive diagnosis of DMD prior to Screening based on documentation of 
clinical findings and prior confirmatory genetic testing using a clinical diagnostic 
genetic test. Genetic report must describe a frameshift deletion, frameshift duplication, 
premature stop (“nonsense”), canonical splice site mutation, or other pathogenic 
variant in the DMD gene fully contained between exons 18 to 79 (inclusive) that is 
expected to lead to absence of dystrophin protein.  
− 
Mutations between or including exons 1 to 17 are not eligible. 
− 
In-frame deletions, in-frame duplications, and variants of uncertain significance (VUS) 
are not eligible.  
− 
Mutations fully contained within exon 45 (inclusive) are not eligible. 
3. Is able to cooperate with motor assessment testing. 
4. 
 
5. 
 
6. Is on a stable daily dose of oral corticosteroids for at least 12 weeks before Screening 
and the dose and regimen are expected to remain constant (except for modifications to 
accommodate changes in weight) throughout the study. 
7. Has rAAVrh74 antibody titers < 1:400 (ie, not elevated) as determined by an ELISA. 
8. Subjects who are sexually active must agree to use, for the entire duration of the study, 
a condom and the female sexual partner must also use a highly effective form of birth 
control (eg, oral contraceptive). Refer to Appendix 1. 
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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
9. Has (a) parent(s) or legal guardian(s) who is (are) able to understand and comply with 
the study visit schedule and all other protocol requirements. 
10. Is willing to provide informed assent (if applicable) and has (a) parent(s) or legal 
guardian(s) who is (are) willing to provide informed consent for the subject to 
participate in the study. 
Exclusion Criteria 
A subject who meets any of the following criteria will be excluded from this study: 
1. 
 screening ECHO or clinical signs and/or 
symptoms of cardiomyopathy. 
2. Has had major surgery within 3 months prior to Day 1 or planned surgery or procedures that 
would interfere with the conduct of the study for any time during this study. 
3. Has presence of any other clinically significant illness, including cardiac, pulmonary, hepatic, 
renal, hematologic, immunologic, or behavioral disease, or infection or malignancy or 
concomitant illness or requirement for chronic drug treatment that in the opinion of the 
Investigator creates unnecessary risks for gene transfer or a medical condition or extenuating 
circumstance that, in the opinion of the Investigator, might compromise the subject’s ability to 
comply with the protocol required testing or procedures or compromise the subject’s 
wellbeing, safety, or clinical interpretability. 
4. Has serological evidence of current, chronic, or active human immunodeficiency virus, 
hepatitis C, or hepatitis B infection. 
5. Has a symptomatic infection (eg, upper respiratory tract infection, pneumonia, pyelonephritis, 
meningitis) within 
 prior to Day 1. 
6. Demonstrates cognitive delay or impairment that could confound motor development in the 
opinion of the Investigator. 
7. Has had treatment with any of the following therapies according to the time frames specified: 
 
− 
Gene therapy 
− 
Cell-based therapy (eg, stem cell transplantation) 
− 
CRISPR/Cas9, or any other form of gene editing 
 
− 
Use of human growth factor or givinostat 
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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
 
− 
Any investigational medication  
− 
Any treatment designed to increase dystrophin expression (eg, Translarna™, 
EXONDYS 51, VILTEPSO™) 
8. Has received a live virus vaccine within 
 or inactive vaccine within 
 of the 
Day 1 visit or expects to receive a vaccination during the 
 after Day 1. 
9. Has abnormal laboratory values considered clinically significant including but not limited to: 
10. Has known hypersensitivity to delandistrogene moxeparvovec or any excipients of 
delandistrogene moxeparvovec. 
11. Family does not want to disclose subject’s study participation with general 
practitioner/primary care physician and other medical providers. 
12. In the opinion of the Investigator, the subject is not likely to be compliant with the study. 
Study Drug, Dosage, and Mode of Administration: delandistrogene moxeparvovec 
(1.33 × 1014 vg/kg) by single IV infusion 
Reference Therapy, Dosage, and Mode of Administration: Placebo (saline, 0.9% sodium chloride 
solution) by single IV infusion 
Duration of Study: The duration of each subject’s participation in the study is expected to be 
approximately 108 weeks: 
Pre-infusion period: Up to 31 days 
Treatment and follow-up period: 104 weeks 
Statistical Methods:  
Sample Size: 
The sample size of this study is based on the power for the primary efficacy endpoint, change in NSAA 
total score from Baseline to Week 52 (Part 1).  
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NAME OF COMPANY: 
Sarepta Therapeutics, Inc. 
215 First Street 
Cambridge, MA 02142 USA 
Phone: +1-617-274-4000 
NAME OF FINISHED PRODUCT: 
delandistrogene moxeparvovec 
 
NAME OF ACTIVE INGREDIENT: 
delandistrogene moxeparvovec  
 
 
 
 
This sample size calculation 
 
 is based on efficacy data from a 
double-blind, placebo-controlled, Phase 2 study as well as comparison against external controls in 
DMD. 
Efficacy Analyses: 
The primary endpoint and some secondary endpoints will be tested in a hierarchical manner using an 
appropriate multiple-testing approach that provides strong control of the familywise Type 1 error rate 
at a 2-sided 0.05 level. The details of the testing procedure will be specified in the statistical analysis 
plan (SAP).  
For the primary endpoint of change in NSAA total score from Baseline to Week 52 (Part 1), summary 
statistics will be provided by treatment group for NSAA total score at Baseline, each post-Baseline 
visit in Part 1, and for change from Baseline to each post-Baseline visit in Part 1. 
 
 
 
As the primary analysis, a restricted maximum likelihood-based mixed model repeated measures 
analysis will be used to compare the 2 treatment groups for change in NSAA total score from Baseline 
to Week 52 (Part 1). In this model, the response vector consists of the change from Baseline in NSAA 
total score at each post-Baseline visit in Part 1. The model will include the covariates of treatment 
group (categorical), visit (categorical), treatment group by visit interaction, age group at randomization 
(categorical), age group at randomization by visit interaction, Baseline NSAA total score, and Baseline 
NSAA total score by visit interaction. All covariates will be fixed effects in this analysis.  
An unstructured covariance matrix will be used to model the within-subject variance-covariance errors. 
If the unstructured covariance structure results in a lack of convergence, the heterogeneous first-order 
autoregressive covariance structure will be used. The Kenward-Roger approximation will be used to 
estimate the denominator degrees of freedom. In the primary analysis, missing data are assumed to be 
missing at random.  
The superiority of delandistrogene moxeparvovec over placebo will be concluded if the test achieves 
statistical significance based on the multiplicity-adjusted testing procedure that will be specified in the 
SAP.  
Interim Analysis: The primary analysis of the study will be performed after all subjects have 
completed Part 1 or have withdrawn early from Part 1. No interim analysis is planned prior to the 
completion of Part 1. 
Data Monitoring Committee: A program-wide independent Data Monitoring Committee (DMC) will 
monitor safety, efficacy, data quality, and the integrity of study. The activities and composition of this 
committee are outlined in the DMC Charter. 
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3. 
TABLE OF CONTENTS, LIST OF TABLES, AND LIST OF 
FIGURES  
TABLE OF CONTENTS 
1. 
TITLE PAGE ................................................................................................................1 
SIGNATURE PAGE FOR SPONSOR ............................................................................................2 
INVESTIGATOR’S AGREEMENT ...............................................................................................3 
2. 
PROTOCOL SUMMARY ............................................................................................4 
2.1. 
Synopsis ........................................................................................................................4 
2.2. 
Schema ........................................................................................................................14 
2.3. 
Schedule of Events .....................................................................................................15 
3. 
TABLE OF CONTENTS, LIST OF TABLES, AND LIST OF FIGURES ...............23 
TABLE OF CONTENTS ...............................................................................................................23 
LIST OF TABLES .........................................................................................................................29 
LIST OF FIGURES .......................................................................................................................29 
4. 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS.............................30 
5. 
INTRODUCTION ......................................................................................................32 
5.1. 
Duchenne Muscular Dystrophy ..................................................................................32 
5.2. 
Current Treatment for Duchenne Muscular Dystrophy ..............................................33 
5.3. 
Delandistrogene Moxeparvovec .................................................................................33 
5.3.1. 
Nonclinical and Clinical Experience With Delandistrogene Moxeparvovec .............33 
5.4. 
Overall Study Rationale ..............................................................................................34 
5.5. 
Benefit/Risk Assessment ............................................................................................35 
6. 
OBJECTIVES AND ENDPOINTS ............................................................................36 
7. 
INVESTIGATIONAL PLAN .....................................................................................40 
7.1. 
Overall Study Design ..................................................................................................40 
7.1.1. 
Pre-infusion Period .....................................................................................................40 
7.1.1.1. 
Subject Identification Number ....................................................................................40 
7.1.1.2. 
Screening Period .........................................................................................................40 
7.1.1.3. 
Baseline Period ...........................................................................................................41 
7.1.2. 
Infusion Period ............................................................................................................41 
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7.1.3. 
52-Week Follow-up Period .........................................................................................42 
7.1.3.1. 
End of Study/Early Termination .................................................................................43 
7.1.4. 
Completion of the Study .............................................................................................43 
7.1.5. 
Study Discontinuation ................................................................................................43 
7.2. 
Scientific Rationale for Study Design ........................................................................44 
7.3. 
Dose Selection Rationale ............................................................................................44 
7.4. 
Study Committees .......................................................................................................46 
8. 
SELECTION AND WITHDRAWAL OF SUBJECTS ..............................................47 
8.1. 
Inclusion Criteria ........................................................................................................47 
8.2. 
Exclusion Criteria .......................................................................................................47 
8.3. 
Screen Failures ............................................................................................................49 
8.4. 
Completion of a Subject’s Participation in the Study .................................................49 
8.5. 
Subject Withdrawal Criteria .......................................................................................49 
8.6. 
Subject Lost To Follow-up .........................................................................................50 
9. 
STUDY TREATMENT ..............................................................................................51 
9.1. 
Description of Study Drug ..........................................................................................51 
9.1.1. 
Package and Labeling .................................................................................................51 
9.1.2. 
Study Drug Preparation ..............................................................................................51 
9.1.3. 
Storage ........................................................................................................................51 
9.2. 
Study Treatment Administered ...................................................................................51 
9.3. 
Randomization and Blinding ......................................................................................52 
9.3.1. 
Randomization ............................................................................................................52 
9.3.2. 
Blinding/Unblinding ...................................................................................................52 
9.3.2.1. 
Blinded and Unblinded Personnel ..............................................................................52 
9.3.2.2. 
Blinding for Muscle Biopsy Assessments ..................................................................52 
9.3.2.3. 
Unblinding Procedures ...............................................................................................52 
9.3.2.4. 
Data Access ................................................................................................................53 
9.4. 
Treatment Compliance ................................................................................................53 
9.5. 
Prior and Concomitant Medications, Physiotherapeutic Interventions, and 
Lifestyle Considerations .............................................................................................53 
9.5.1. 
Corticosteroids ............................................................................................................53 
9.5.1.1. 
Pre-infusion Immunosuppressants ..............................................................................53 
9.5.1.2. 
Post-infusion Immunosuppressants ............................................................................54 

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9.5.2. 
Prohibited Medications ...............................................................................................54 
9.5.3. 
Lifestyle Considerations .............................................................................................55 
9.5.3.1. 
Infection Precautions ..................................................................................................55 
9.6. 
Safety Monitoring .......................................................................................................55 
9.6.1. 
Safety Monitoring for Liver Chemistry Tests ............................................................55 
9.6.1.1. 
Additional Investigations for Liver Function .............................................................55 
9.6.1.2. 
AESIs for Liver Function ...........................................................................................56 
9.6.2. 
Safety Monitoring for Hypersensitivity ......................................................................56 
9.6.2.1. 
Additional Investigations for Hypersensitivity ...........................................................56 
9.6.2.2. 
AESIs for Hypersensitivity .........................................................................................56 
9.6.3. 
Safety Monitoring for Immune-mediated Myositis ....................................................57 
9.6.3.1. 
Additional Investigations for Immune-mediated Myositis .........................................57 
9.6.3.2. 
AESIs for Immune-mediated Myositis .......................................................................57 
9.6.4. 
Safety Monitoring for Thrombotic Microangiopathy (TMA) ....................................57 
9.6.4.1. 
Additional Investigations for TMA ............................................................................57 
9.6.4.2. 
AESIs for TMA ..........................................................................................................58 
9.6.5. 
Safety Monitoring for Platelet Count Results .............................................................58 
9.6.5.1. 
Additional Investigations for Platelet Count ..............................................................58 
9.6.5.2. 
AESIs for Platelet Count ............................................................................................58 
9.6.6. 
Safety Monitoring for Rhabdomyolysis .....................................................................58 
9.6.6.1. 
Additional Investigations for Rhabdomyolysis ..........................................................59 
9.6.6.2. 
AESIs for Rhabdomyolysis ........................................................................................59 
9.6.6.3. 
Risk of Rhabdomyolysis due to Anesthesia ...............................................................59 
9.6.7. 
Safety Monitoring for Troponin Increased/Myocarditis .............................................59 
9.6.7.1. 
Additional Investigations for Troponin Increased/Myocarditis .................................60 
9.6.7.2. 
AESIs for Troponin Increased/Myocarditis ................................................................60 
9.7. 
Treatment Overdose ....................................................................................................60 
10. 
STUDY ASSESSMENTS ..........................................................................................61 
10.1. 
Schedule of Events .....................................................................................................61 
10.2. 
Screening/Baseline Assessments ................................................................................61 
10.2.1. 
Informed Consent and Assent .....................................................................................61 
10.2.2. 
Demographic/Medical History ...................................................................................61 
10.2.3. 
Genetic Diagnostics ....................................................................................................61 

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10.3. 
Efficacy Assessments .................................................................................................61 
10.3.1. 
Functional Assessments ..............................................................................................61 
10.3.1.1. 
North Star Ambulatory Assessment ...........................................................................62 
10.3.1.2. 
Time to Ascend 4 Steps ..............................................................................................62 
10.3.1.3. 
100-Meter Walk/Run ..................................................................................................62 
10.3.2. 
Wearable Device .........................................................................................................63 
10.3.3. 
Delandistrogene Moxeparvovec Dystrophin Expression ...........................................63 
10.3.6.1. 
Patient-Reported Outcomes Measurement Information System ................................64 
10.4. 
Safety Assessments .....................................................................................................66 
10.4.1. 
Adverse Events ...........................................................................................................66 
10.4.2. 
Demographic/Medical History ...................................................................................66 
10.4.3. 
Vital Signs Measurements, Weight, and Height .........................................................66 
10.4.4. 
Physical Examination .................................................................................................67 
10.4.5. 
Electrocardiograms and Echocardiograms .................................................................67 
10.4.6. 
Laboratory Assessments .............................................................................................67 
10.4.6.1. 
Routine Clinical Laboratory Tests ..............................................................................67 
10.4.6.3. 
Virus Serology ............................................................................................................69 
10.4.6.4. 
Concomitant Medications and Physiotherapeutic Interventions ................................69 
10.4.8. 
Use/Analysis of Muscle Biopsies ...............................................................................70 
11. 
ADVERSE EVENTS AND OTHER SAFETY INFORMATION ............................72 
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11.1. 
Definitions ..................................................................................................................72 
11.1.1. 
Adverse Event .............................................................................................................72 
11.1.2. 
Serious Adverse Event ................................................................................................72 
11.1.3. 
Suspected Unexpected Serious Adverse Reactions ....................................................73 
11.1.4. 
Adverse Event of Special Interest ...............................................................................73 
11.1.5. 
Special Situations ........................................................................................................73 
11.2. 
Collection of Adverse Events .....................................................................................74 
11.2.1. 
Clinical Laboratory Abnormalities .............................................................................74 
11.2.2. 
Disease Progression ....................................................................................................75 
11.3. 
Classification of Adverse Events ................................................................................75 
11.3.1. 
Relationship to Study Drug ........................................................................................75 
11.3.2. 
Relationship to Study Procedures ...............................................................................75 
11.3.3. 
Relationship to Underlying Disease ...........................................................................75 
11.3.4. 
Severity of Adverse Events ........................................................................................76 
11.3.5. 
Outcomes of Adverse Events ......................................................................................76 
11.3.6. 
Action Taken Regarding the Study Drug ...................................................................76 
11.3.7. 
Expectedness of Adverse Events ................................................................................76 
11.4. 
Recording of Adverse Events .....................................................................................76 
11.4.1. 
Reporting Serious Adverse Events .............................................................................77 
11.4.1.1. 
Serious Adverse Events ..............................................................................................77 
11.4.1.2. 
Suspected Unexpected Serious Adverse Reactions ....................................................78 
11.4.2. 
Reporting Special Situations .......................................................................................78 
11.4.2.1. 
Overdose .....................................................................................................................78 
11.4.2.2. 
Medication Error .........................................................................................................78 
11.4.2.3. 
Accidental/Occupational Exposure ............................................................................78 
11.4.2.4. 
Product Misuse/Abuse ................................................................................................78 
11.4.2.5. 
Adverse Events of Special Interest .............................................................................78 
11.4.3. 
Miscellaneous .............................................................................................................80 
11.4.3.1. 
Responsibilities of the Investigator ............................................................................80 
11.4.3.2. 
Responsibilities of the Sponsor ..................................................................................80 
12. 
STATISTICAL CONSIDERATIONS .......................................................................81 
12.1. 
Statistical Hypotheses .................................................................................................81 
12.2. 
Sample Size Determination ........................................................................................81 

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12.3. 
Analysis Populations ..................................................................................................81 
12.4. 
Statistical Analyses .....................................................................................................82 
12.4.1. 
Subject Disposition .....................................................................................................82 
12.4.2. 
Demographic and Baseline Characteristics ................................................................82 
12.4.3. 
Concomitant Medications ...........................................................................................82 
12.4.4. 
Efficacy Analyses .......................................................................................................82 
12.4.4.1. 
Analyses of Primary Efficacy Endpoint .....................................................................82 
12.4.4.2. 
Analyses of Key Secondary Endpoints .......................................................................83 
12.4.5. 
Safety Analyses ..........................................................................................................83 
12.4.5.1. 
Adverse Events ...........................................................................................................83 
12.4.5.2. 
Other Safety Assessments ...........................................................................................84 
12.5. 
Interim Analysis ..........................................................................................................84 
12.6. 
Data Monitoring Committee .......................................................................................84 
13. 
DATA COLLECTION, QUALITY ASSURANCE, AND MANAGEMENT ..........85 
13.1. 
Study Monitoring ........................................................................................................85 
13.2. 
Recording of Data .......................................................................................................85 
13.3. 
Quality Assurance .......................................................................................................86 
13.4. 
Retention of Study Documents ...................................................................................86 
14. 
ETHICS AND OTHER SPECIAL REQUIREMENTS .............................................87 
14.1. 
Institutional and Ethics Review ..................................................................................87 
14.2. 
Informed Consent and Assent .....................................................................................87 
14.3. 
Compliance with the Protocol ....................................................................................87 
14.4. 
Confidentiality ............................................................................................................88 
15. 
STUDY DOCUMENTATION AND GENERAL INFORMATION .........................89 
15.1. 
General Information ....................................................................................................89 
15.2. 
Essential Study Documents ........................................................................................89 
15.3. 
Dissemination of Study Results ..................................................................................89 
15.4. 
Publication Policy .......................................................................................................89 
15.5. 
Product Handling and Complaints Reporting .............................................................89 
16. 
LIST OF REFERENCES ............................................................................................90 
APPENDIX 1. GUIDANCE ON CONTRACEPTION USE AND PREGNANCY 
TESTING ....................................................................................................................93 
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APPENDIX 3. QUESTIONNAIRES .........................................................................................95 
APPENDIX 4. PROTOCOL VERSION HISTORY ..................................................................96 
 
LIST OF TABLES 
Table 1: Schedule of Events – Part 1 .............................................................................................15 
Table 2: Schedule of Events – Part 2 .............................................................................................19 
 
LIST OF FIGURES 
Figure 1: 
Study Design Schematic Part 1 ...................................................................................14 
Figure 2: 
Study Design Schematic Part 2 Crossover .................................................................14 
 
 

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4. 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS 
Abbreviation 
Definition 
10MWR 
10-meter walk/run 
100MWR 
100-meter walk/run 
ADL 
Activities of daily living 
AE 
Adverse event 
AESI 
Adverse events of special interest 
ALP 
Alkaline phosphatase 
ALT 
Alanine aminotransferase 
AST 
Aspartate aminotransferase 
CFR 
Code of Federal Regulations 
 
 
 
  
 
 
 
 
 
 
CMV 
Cytomegalovirus 
CRO 
Contract Research Organization 
CTCAE 
Common Terminology Criteria for Adverse Events 
DMC 
Data Monitoring Committee 
DMD 
Duchenne muscular dystrophy 
DNA 
Deoxyribonucleic acid 
EBV 
Epstein-Barr virus 
ECG 
Electrocardiogram 
ECHO 
Echocardiogram 
eCRF 
Electronic case report form 
ELISA 
Enzyme-linked immunosorbent assay 
 
 
 
 
FDA 
Food and Drug Administration 
GCP 
Good Clinical Practice 
GGT 
Gamma-glutamyl transferase 
GLDH 
Glutamate dehydrogenase 
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Abbreviation 
Definition 
HEENT 
Head, ears, eyes, nose, throat 
HH6 
Human Herpesvirus 6 
HIV 
Human immunodeficiency virus 
hsCRP 
High-sensitivity C-reactive protein 
ICH 
International Council for Harmonisation 
IEC 
Independent Ethics Committee 
IF 
Immunofluorescence 
INR 
International normalized ratio 
IRB 
Institutional Review Board 
IRT 
Interactive response technology 
ITT 
Intent-to-treat 
IV 
Intravenous(ly) 
 
 
mITT 
Modified Intent-to-Treat 
NSAA 
North Star Ambulatory Assessment 
PDPF 
Percent dystrophin positive fibers 
PROMIS 
Patient-Reported Outcomes Measurement Information System 
PT 
Preferred term 
qPCR 
Quantitative polymerase chain reaction 
RNA 
Ribonucleic acid 
SAE 
Serious adverse event 
SAP 
Statistical analysis plan 
SOC 
System organ class 
SUSAR 
Suspected Unexpected Serious Adverse Reactions 
SV95C 
Stride velocity 95th centile 
TEAE 
Treatment-emergent adverse event 
TMA 
Thrombotic microangiopathy 
ULN 
Upper limit of normal 
VAS 
Visual analog scale 
WHODrug 
World Health Organization Drug Dictionary 
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5. 
INTRODUCTION 
5.1. 
Duchenne Muscular Dystrophy 
Duchenne muscular dystrophy (DMD) is an X-linked degenerative neuromuscular disease 
caused by mutations in the dystrophin gene. Duchenne muscular dystrophy occurs in 
approximately 1 in 5000 males worldwide (Mendell 2012). The mutations that cause DMD 
typically disrupt the dystrophin messenger ribonucleic acid reading frame and prevent 
production of the corresponding protein. Dystrophin is a critically important part of the protein 
complex that connects the cytoskeleton of a muscle fiber to the cell membrane and extracellular 
matrix and acts to prevent muscle membrane damage during eccentric contraction. In the absence 
of dystrophin, the stress of muscle eccentric contraction causes widespread chronic and 
progressive muscle damage and ultimately replacement by fat and fibrotic tissue. The clinical 
effect of this disrupted dystrophin reading frame is thus ultimately fatal. 
Duchenne muscular dystrophy is usually diagnosed between the ages of 3 to 5 years 
(Ciafaloni 2009), when toddlers develop a waddling gait, lordosis, toe walking, calf hypertrophy, 
and difficulty climbing stairs. Over time, ambulation becomes increasingly abnormal. By 8 years 
of age, without glucocorticoids, most patients lose the ability to rise from the floor and climb 
stairs, have an increasingly labored gait, and often fall while walking, leading to the increased 
use of mobility devices such as strollers and scooters. Patients with DMD spend less time 
walking than healthy boys and walk more slowly than healthy boys and are significantly less 
active than healthy boys of similar age (McDonald 2002, McDonald 2005). By 10 to 14 years of 
age, most boys lose ambulation and are wheelchair dependent.  
In addition to progressive muscle weakness and wasting, manifestations of DMD typically 
include cardiac and pulmonary symptoms in addition to several well-understood laboratory 
abnormalities such as an increase in serum creatine kinase (CK). While pulmonary and cardiac 
functions are generally normal during early childhood, they progressively worsen over time, and 
patients typically die from cardiac or respiratory failure in their 20s (Brooke 1983, Eagle 2002). 
Boys with DMD have a resting heart rate that is consistently higher than healthy boys even when 
cardiac function remains normal. Although elevation in resting heart rate in this patient 
population is likely multifactorial, it is associated with increased risk of cardiomyopathy 
(Thomas 2012), which usually manifests after 10 years of age as dilated cardiomyopathy with 
reduced left ventricular ejection fraction. The prevalence of cardiomyopathy in DMD patients 
increases with age and disease progression, with the majority of patients affected by age 18 
(Gulati 2005, Spurney 2014). 
Subclinical impairment of respiratory muscle function occurs in ambulatory patients 
(Khirani 2014, Mayer 2015), but clinical impairment of respiratory function usually only 
happens after loss of ambulation. Respiratory insufficiency typically starts at night, resulting in 
disturbed sleep, morning drowsiness and headaches, loss of appetite, and frequent pulmonary 
infections. Congestive heart failure or sudden death occurs in 20% of patients (Mercuri 2013). 
In addition to the clinical manifestations, patients with DMD have grossly elevated CK values 
due to leakage of the enzyme from degenerating muscle fibers (Zatz 1991). Early in the disease, 
CK levels are usually 50 to 300 × the upper limit of normal (ULN), and levels tend to decrease 
over time as muscle is lost and replaced by fibrotic tissue and fat. High transaminase levels 

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(alanine aminotransferase [ALT] and aspartate aminotransferase [AST] up to approximately 
22 × ULN) and lactate dehydrogenase levels, originating from degenerating muscle, are also 
generally observed in these patients (McMillan 2011).  
5.2. 
Current Treatment for Duchenne Muscular Dystrophy 
To date, there are limited treatment options for patients suffering from DMD, none of which 
reverse the course of this debilitating and ultimately fatal disease.  
Management of DMD requires a multidisciplinary approach that includes both preventive and 
therapeutic measures, as recommended by DMD Care Considerations Working Group and the 
American Academy of Neurology (Bushby 2010, AAN 2016, Birnkrant 2018, Passamano 2012). 
Treatment includes corticosteroids, rehabilitation and pain management, orthopedic surgery, and 
respiratory interventions. Treatments designed to increase dystrophin production via exon-
skipping or ribosomal readthrough of premature stop codons are available in some countries for 
a minority of patients with mutations amenable to their mechanism of action. While these 
options may improve life expectancy of DMD patients, none are capable of halting or reversing 
the effects of the disease, only reducing the rate of decline in muscle strength, or managing the 
symptoms and complications associated with DMD.  
At this time, there exist limited disease management-focused treatment options for DMD. 
A significant unmet medical need still exists for DMD patients. As a gene therapy product, 
delandistrogene moxeparvovec has the potential to deliver functional dystrophin, thus addressing 
the root cause of the disease and potentially reversing the clinical course of decline and thereby 
satisfying a significant unmet medical need. 
5.3. 
Delandistrogene Moxeparvovec 
Sarepta and F. Hoffmann-La Roche are collaborating with respect to global development of 
delandistrogene moxeparvovec for the treatment of patients with DMD. Delandistrogene 
moxeparvovec is a gene therapy designed to treat the underlying biological cause of DMD by 
replacing dysfunctional or missing dystrophin protein with a functional truncated dystrophin, 
called delandistrogene moxeparvovec dystrophin, in cardiac and skeletal muscle; the key tissues 
affected in this lethal degenerative disease. Thus, delandistrogene moxeparvovec may address 
the root cause of DMD, alter the course of the disease, and address a significant unmet medical 
need. 
For more background information on delandistrogene moxeparvovec, refer to the Investigator’s 
Brochure. 
5.3.1. 
Nonclinical and Clinical Experience With Delandistrogene Moxeparvovec 
The effects of delandistrogene moxeparvovec treatment were evaluated at 3 doses in the mdx 
mouse. Results from these studies are summarized in Section 7.3 as well as the Investigator’s 
Brochure.  
There are multiple ongoing clinical studies with delandistrogene moxeparvovec; for a detailed 
summary of clinical findings to date, refer to the Investigator’s Brochure. 
On 22 June 2023, delandistrogene moxeparvovec (ELEVIDYS) received an accelerated approval 
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DMD, who have a confirmed mutation in the DMD gene. At the time of this amendment, 
ELEVIDYS has also been approved for the treatment of ambulatory pediatric patients aged 
4 through 5 years with DMD in United Arab Emirates, Qatar, Bahrain, Kuwait, and Oman. 
5.4. 
Overall Study Rationale 
Duchenne muscular dystrophy is a rare, serious, debilitating, and ultimately fatal disease for 
which there is an urgent need to develop safe and effective therapies. To meet this urgency and 
the needs of the patient community, this study evaluates the effect of delandistrogene 
moxeparvovec compared with placebo in subjects with DMD. The endpoints selected for the 
study (see Section 6) are recognized as appropriate measures of disease severity and treatment 
effect and are widely used in clinical practice. 
All subjects enrolled in this study will be on background corticosteroids allowing for assessment 
of the effect of delandistrogene moxeparvovec over and above improvements that would be 
expected from corticosteroids alone, which are the current pharmacological standard of care for 
most patients in real-world practice.  
Gene replacement therapy has been studied for the past 10 to 15 years and shows favorable 
results in nonclinical studies in mice and canine species deficient in dystrophin. The goal of 
delandistrogene moxeparvovec therapy is to induce the expression of the delandistrogene 
moxeparvovec dystrophin protein in skeletal and cardiac muscle in order to increase strength and 
protect from contraction-induced injury. Correction of the underlying genetic defect in DMD 
using gene replacement with delandistrogene moxeparvovec is a promising treatment. Duchenne 
muscular dystrophy affects all skeletal muscles in the body, in addition to the diaphragm and 
heart. As such, a systemic approach is necessary to provide the best possible benefit to patients. 
Utilizing the rAAVrh74 serotype allows for efficient transduction of cardiac, skeletal, and 
diaphragm muscle without the risk of regional delivery strategies. Increased dystrophin 
expression in vivo may potentially improve patient’s muscle function and, importantly, may 
preserve diaphragm and cardiac muscle. Delandistrogene moxeparvovec appears to have a 
favorable safety profile and to be generally well tolerated in clinical and nonclinical studies. 
All subjects will be screened for pre-existing antibodies to rAAVrh74.  
Subjects with mutations between or including exons 1 to 17 will be excluded from this study to 
minimize the risk of immune response to the expressed delandistrogene moxeparvovec 
dystrophin (Mendell 2010). Additional information may be found in the Investigator’s Brochure.  
Subjects who have exon 45 (inclusive), or in-frame deletions, in-frame duplications, and variants 
of uncertain significance (“VUS”) on molecular characterization of the DMD gene will be 
excluded from this study. Literature suggests that patients with these mutations exhibit a milder 
phenotype and thus may impact efficacy results if included. 
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5.5. 
Benefit/Risk Assessment 
Nonclinical data suggest a positive benefit/risk relationship and support the clinical investigation 
of delandistrogene moxeparvovec gene transduction in DMD subjects. Efficacy studies in the 
mdx mouse model of DMD have demonstrated significant functional improvements in several 
disease-associated phenotypes, including specific force in the tibialis anterior and diaphragm, 
muscle and histological improvements including central nucleation, normalization of fiber size, 
and decreased fibrosis. Additional information can be found in the Investigator’s Brochure. 
Clinical experience from ongoing Phase 1 and 2 studies demonstrates an acceptable benefit/risk 
profile based on robust demonstration of transduction and delandistrogene moxeparvovec 
dystrophin expression; reduced CK levels; and improvement in functional outcome measures ; 
and a safety profile of monitorable, manageable, and reversible risks of study therapy, including 
liver injury, nausea and vomiting, thrombocytopenia, infusion site reaction, and hypersensitivity. 
A risk of immune-mediated myositis in the setting of transgene immune reaction was identified 
in association with DMD gene mutations that are excluded from this study. Detailed information 
about the results of completed and ongoing clinical studies, the known and anticipated benefits 
and risks and expected adverse events of delandistrogene moxeparvovec may be found in the 
Investigator’s Brochure. 
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6. 
OBJECTIVES AND ENDPOINTS 
Objectives 
Endpoints 
Primary 
• 
To evaluate the effect of delandistrogene 
moxeparvovec on physical function as assessed 
by the North Star Ambulatory Assessment 
(NSAA) score 
• 
Change in NSAA total score from Baseline 
to Week 52 (Part 1) 
Secondary 
• 
To evaluate the effect of delandistrogene 
moxeparvovec on physical function as assessed 
by: 
− 
Number of skills gained or improved on the 
NSAA 
• 
Number of skills gained or improved at 
Week 52 (Part 1) as measured by the NSAA 
• 
To evaluate delandistrogene moxeparvovec 
dystrophin expression from delandistrogene 
moxeparvovec at 12 weeks (Part 1) as measured 
by western blot of biopsied muscle tissue 
• 
Quantity of delandistrogene moxeparvovec 
dystrophin protein expression at Week 12 
(Part 1) as measured by western blot 
• 
To evaluate the effect of delandistrogene 
moxeparvovec on timed function tests as 
assessed by measuring: 
− 
Time to rise from the floor  
− 
100-meter walk/run (100MWR)  
− 
Time to ascend 4 steps  
− 
10-meter walk/run (10MWR) 
• 
Change in time to rise from the floor from 
Baseline to Week 52 (Part 1)  
• 
Change in time of 100MWR from Baseline 
to Week 52 (Part 1) 
• 
Change in time to ascend 4 steps from 
Baseline to Week 52 (Part 1) 
• 
Change in time of 10MWR from Baseline 
to Week 52 (Part 1) 
• 
To evaluate the effect of delandistrogene 
moxeparvovec on stride velocity 95th centile 
(SV95C) as measured by a wearable device 
• 
Change in SV95C from Baseline to 
Week 52 (Part 1) 
• 
To evaluate subject (parent/caregiver proxy) 
reported Mobility and Upper Extremity 
Function using the Patient Reported Outcomes 
Measurement Information System (PROMIS®) 
tool 
• 
Change in PROMIS score in Mobility and 
Upper Extremity from Baseline to Week 52 
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• 
To evaluate the safety of delandistrogene 
moxeparvovec 
• 
Incidence of treatment-emergent adverse 
events (TEAEs)  
• 
Incidence of serious adverse events (SAEs) 
• 
Incidence of adverse events of special 
interest (AESIs) 
• 
Clinically significant changes in vital signs 
and physical examination findings 
• 
Clinically significant changes in safety 
laboratory assessments, electrocardiograms 
(ECGs), and echocardiograms (ECHOs) 
 
 
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7. 
INVESTIGATIONAL PLAN 
7.1. 
Overall Study Design 
This is a Phase 3, randomized, double-blind, placebo-controlled 2-part study of systemic gene 
delivery of delandistrogene moxeparvovec in approximately 120 male DMD ambulatory subjects 
who are ≥ 4 to < 8 years of age. The total duration of each subject’s participation in the study is 
expected to be approximately 108 weeks, inclusive of an up to 4-week Pre-infusion Period 
(Section 7.1.1) and a 52-week treatment and follow-up period (Section 7.1.2) in Part 1 and 
Part 2. All subjects will have the opportunity to receive intravenous (IV) delandistrogene 
moxeparvovec (1.33 × 1014 vg/kg) in either Part 1 or Part 2. 
Schematics of the study design is provided in Section 2.2. The schedules of events are provided 
in Section 2.3.  
7.1.1. 
Pre-infusion Period 
Prior to undergoing any study procedures, subjects will provide informed consent/assent and 
parent(s), or legal guardian(s) will provide informed consent for the subject to participate in the 
study.  
7.1.1.1. 
Subject Identification Number 
Every subject will be assigned a 
digit identification number 
 
. 
The interactive response technology (IRT) will assign subject numbers. Subject numbers will not 
be re-used if a subject is a screen failure. Refer to the IRT Manual for additional information. 
7.1.1.2. 
Screening Period 
During the Screening Period, which begins a maximum of 31 days prior to the Day 1 infusion, 
various assessments will be performed.  
A blood draw for an enzyme-linked immunosorbent assay (ELISA) and provision of the 
wearable device are required to be performed at the initial Screening visit. Subjects will be 
provided with a wearable device to collect daily physical activities. Subjects should attempt to 
wear this device 
. Subjects must return the wearable device in 
the event of screen failure, early termination, or after study completion. Refer to the Wearable 
Investigator Manual for additional information. It is recommended that the following 
assessments occur at minimum during the initial Screening visit: collection of the subject’s 
medical history, demographics, documentation of DMD genotyping, select clinical laboratory 
assessments which inform eligibility, serology tests, vital signs, ECHO, the NSAA (including the 
timed function tests of time to rise from the floor and the 10MWR), provision of the wearable 
device, and full physical examination (including weight).  
During the Screening Period, additional assessments will include ECG, urinalysis, and a review 
of adverse events (AEs) and concomitant medications and procedures. 
 
 
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All laboratory samples obtained will be stored 
 if permitted by the 
informed consent/assent form regardless of screening outcome and maintained for up to 
 
following the end of the study or per local regulations. 
Refer to the Schedule of Events in Section 2.3 for an outline of assessments performed during 
the Screening Period. 
7.1.1.3. 
Baseline Period 
The Baseline Period will start when eligibility is confirmed and ends on the day prior to the 
Day 1 infusion. During this period, vital signs, select clinical laboratory assessments,  
 
. A brief physical examination (including height, ulnar 
length, and weight) will be performed. 
 
 
Physical functional assessments to be performed will include the NSAA (including the timed 
function tests of time to rise from the floor and the 10MWR although the timed components are 
not part of the NSAA), time to ascend 4 steps, and the 100MWR. The NSAA will be 
 
. Functional assessment data collected at Baseline will be used for the efficacy endpoint 
analysis as described in Section 12.4.4 and detailed in the statistical analysis plan (SAP). 
A subset of subject and parent/caregiver proxies will complete PROMIS measures 
 
 
 
 
.  
 
 
 
Refer to the Schedule of Events in Section 2.3 for an outline of assessments performed during 
the Baseline Period. 
7.1.2. 
Infusion Period 
On the day prior to study drug infusion, subjects will be started on additional steroid for 
immunosuppression; see Section 9.5.1.1.  
The study drug infusion will occur on Day 1 of Part 1 and Part 2. In Part 1, approximately 
60 subjects will receive IV delandistrogene moxeparvovec (1.33 × 1014 vg/kg) and 
approximately 60 subjects will receive matching infusion volumes of placebo (saline, 
0.9% sodium chloride solution). In Part 2, subjects who received placebo in Part 1 will receive 
IV delandistrogene moxeparvovec, and subjects who received delandistrogene moxeparvovec 
in Part 1 will receive placebo in order to maintain blinding throughout the study. Refer to the 
study-specific Pharmacy Manual for additional information. 
All subjects, parents/caregivers, Investigators, and site staff, with the exception of the unblinded 
site pharmacist, will be blinded to the treatment the subject receives (delandistrogene 
moxeparvovec or placebo). Refer to the study blinding plan for further details. 
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On Day 1, vital signs, 
. A brief 
physical examination and an ECG will be performed. Weight for dosing should be obtained 
either prior to Day 1 or on Day 1; refer to the Pharmacy Manual for additional information.  
Refer to the Schedule of Events in Section 2.3 for an outline of assessments performed on Day 1. 
Prior to dosing in Part 2, the unblinded contract research organization (CRO) medical director 
will review the rAAVrh74 antibody titers and treatment allocation and communicate whether 
dosing may proceed. 
7.1.3. 
52-Week Follow-up Period 
Subjects will receive 1 mg/kg additional glucocorticoid (prednisone equivalent) for at least 
60 days after the infusion; however, earlier tapering to manage an AE may be permitted with 
Medical Monitor approval in Part 1 and Part 2. Post-infusion added glucocorticoid for 
immunosuppression should be increased to 2 mg/kg daily if gamma-glutamyl transferase (GGT) 
level is confirmed to be 
 U/L or there are other clinically significant liver function 
abnormalities following infusion. A tapering dose of glucocorticoid will be implemented based 
on individual subject’s response to the infusion as assessed by liver function monitoring with 
GGT. Refer to Section 9.5.1.2. 
Subjects will be followed for up to 52 weeks in Part 1 and Part 2 and will complete follow-up 
visits at the following time points: 
 
 
 
Safety will be assessed by monitoring of vital signs, physical examinations, ECGs, ECHOs, 
TEAEs, SAEs, and select laboratory assessments.  
 
 
 
 
Physical functional assessments will be performed throughout the study and will include the 
NSAA (including the timed function tests of time to rise from the floor and the 10MWR 
although the timed components are not part of the NSAA), time to ascend 4 steps, and the 
100MWR.  
Subjects will be provided with a wearable device to collect daily physical activities. Subjects 
should attempt to wear the device 
 
 
. Subjects must return the wearable device in the event of screen failure, early 
termination, or after study completion. Refer to the Wearable Investigator Manual for additional 
information. 
A subset of subject and parent/caregiver proxies will complete PROMIS Mobility, Upper 
Extremity 
 domains (proxy report for pediatric), 
 
 
 
 
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7.1.3.1. 
End of Study/Early Termination 
For subjects who complete the study, the last study visit will occur at Week 52 of Part 2. For 
subjects who terminate the study early, an early termination visit will be required as shown in the 
Schedule of Events (Section 2.3).  
The NSAA (including the timed function tests of time to rise from floor and 10MWR although 
the timed components are not part of the NSAA), will be completed 
 
 
. 
After completion of the Part 2 Week 52 assessments, subjects will be enrolled into an extension 
study to assess long-term safety and efficacy. Subjects will be followed for long-term safety and 
efficacy in the extension study. Subjects will be followed for at least 5 years following their 
delandistrogene moxeparvovec infusion. 
7.1.4. 
Completion of the Study 
The study will be considered complete when all subjects have completed the Week 52 visit of 
Part 2 or otherwise discontinued from the study. 
Study sites who did not enroll a subject will be closed. A study site will be considered closed 
when all required study documents and study supplies, including wearable devices, have been 
collected and a study-site closure visit has been performed. 
7.1.5. 
Study Discontinuation 
If the Sponsor, Investigator, Medical Monitor, Study Monitor, Institutional Review Board 
(IRB)/Independent Ethics Committee (IEC), or appropriate regulatory/competent authority 
officials discover conditions arising during the study that indicate the study should be 
temporarily suspended or halted or that a study center should be closed, appropriate action may 
be taken after consultation among the Sponsor, Investigator, and others as needed. 
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Conditions that may warrant termination of the study or closure of an individual site include, but 
are not limited to, the following: 
• The discovery of an unexpected, serious, or unacceptable risk to subjects enrolled in 
the study 
• A decision by the Sponsor to suspend or discontinue testing, evaluation, or 
development of the product 
• Failure of the Investigator to enroll subjects into the study at an acceptable rate 
• Failure of the Investigator to comply with pertinent regulations of IRB/IEC or 
appropriate regulatory/competent authorities 
• Failure of the Investigator to comply with the protocol 
• Submission of knowingly false information from the research facility to the Sponsor, 
Study Monitor, IRB/IEC, or regulatory/competent authority 
• Insufficient adherence or noncompliance with the clinical study protocol and global 
GCP regulations, directives, guidelines, and laws such as the Pharmaceutical and 
Medical Device Act, and the clinical study protocol, as applicable 
7.2. 
Scientific Rationale for Study Design 
The placebo-controlled design of the double-blind treatment period was chosen to reduce 
potential bias during data collection and evaluation of outcome parameters. Both the placebo and 
delandistrogene moxeparvovec groups will be allowed to continue standard of care steroid 
therapy as well as non-pharmacological interventions such as physiotherapy during the study. 
The 52-week double-blind follow-up duration of the study provides sufficient time to obtain 
safety and efficacy data post infusion. The Part 2 crossover allows for all subjects to have the 
opportunity to receive delandistrogene moxeparvovec. Following completion of Study 
SRP-9001-301, subjects may enter a separate, long-term extension study where additional safety 
and efficacy data will be collected. In the long-term extension study subjects will be followed for 
at least 5 years following their delandistrogene moxeparvovec infusion. 
7.3. 
Dose Selection Rationale 
The dose of delandistrogene moxeparvovec selected for use in this study is 1.33 × 1014 vg/kg 
(quantitative polymerase chain reaction [qPCR] with linear standard) and was chosen based on 
results from nonclinical studies where the delivery of delandistrogene moxeparvovec 
systemically demonstrated successful gene transduction to all skeletal muscles assessed, heart, 
and diaphragm in the mdx mouse model.  
In addition to the clinical evidence presented in Section 5.5, the clinical dose selection is also 
supported by the preliminary PK/PD modeling and simulations based on clinical data integrated 
across Studies SRP-9001-101 and SRP-9001-102 Part 1. 
 
 
 
 
 
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7.4. 
Study Committees 
A program-wide independent Data Monitoring Committee (DMC) will assist in the monitoring 
of safety, efficacy, data quality, and the integrity of study. See Section 12.6 for details. 

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8. 
SELECTION AND WITHDRAWAL OF SUBJECTS 
8.1. 
Inclusion Criteria 
A subject must meet all of the following criteria to be eligible to participate in this study: 
1. Is male at birth, ambulatory, and ≥ 4 to < 8 years of age at the time of randomization. 
2. Has a definitive diagnosis of DMD prior to Screening based on documentation of clinical 
findings and prior confirmatory genetic testing using a clinical diagnostic genetic test. 
Genetic report must describe a frameshift deletion, frameshift duplication, premature stop 
(“nonsense”), canonical splice site mutation, or other pathogenic variant in the DMD 
gene fully contained between exons 18 to 79 (inclusive) that is expected to lead to 
absence of dystrophin protein.  
a. Mutations between or including exons 1 to 17 are not eligible.  
b. In-frame deletions, in-frame duplications, and variants of uncertain significance 
(“VUS”) are not eligible.  
c. Mutations fully contained within exon 45 (inclusive) are not eligible. 
3. Is able to cooperate with motor assessment testing. 
4. 
 
5. 
 
6. Is on a stable daily dose of oral corticosteroids for at least 12 weeks before Screening and 
the dose and regimen are expected to remain constant (except for modifications to 
accommodate changes in weight) throughout the study. 
7. Has rAAVrh74 antibody titers < 1:400 (ie, not elevated) as determined by an ELISA. 
8. Subjects who are sexually active must agree to use, for the entire duration of the study, 
a condom and the female sexual partner must also use a highly effective form of birth 
control (eg, oral contraceptive). Refer to Appendix 1. 
9. Has (a) parent(s) or legal guardian(s) who is (are) able to understand and comply with the 
study visit schedule and all other protocol requirements. 
10. Is willing to provide informed assent (if applicable) and has (a) parent(s) or legal 
guardian(s) who is (are) willing to provide informed consent for the subject to participate 
in the study. 
8.2. 
Exclusion Criteria 
A subject who meets any of the following criteria will be excluded from this study: 
1. 
 screening ECHO or clinical signs 
and/or symptoms of cardiomyopathy. 
2. Has had major surgery within 3 months prior to Day 1 or planned surgery or procedures 
that would interfere with the conduct of the study for any time during this study. 
3. Has presence of any other clinically significant illness, including cardiac, pulmonary, 
hepatic, renal, hematologic, immunologic, or behavioral disease, or infection or 
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malignancy or concomitant illness or requirement for chronic drug treatment that in the 
opinion of the Investigator creates unnecessary risks for gene transfer or a medical 
condition or extenuating circumstance that, in the opinion of the Investigator, might 
compromise the subject’s ability to comply with the protocol required testing or 
procedures or compromise the subject’s wellbeing, safety, or clinical interpretability. 
4. Has serological evidence of current, chronic, or active human immunodeficiency virus, 
hepatitis C, or hepatitis B infection. 
5. Has a symptomatic infection (eg, upper respiratory tract infection, pneumonia, 
pyelonephritis, meningitis) within 
 prior to Day 1. 
6. Demonstrates cognitive delay or impairment that could confound motor development in 
the opinion of the Investigator. 
7. Has had treatment with any of the following therapies according to the time frames 
specified: 
 
− Gene therapy 
− Cell based therapy (eg, stem cell transplantation) 
− CRISPR/Cas9, or any other form of gene editing 
 
− Use of human growth factor or givinostat 
 
− Any investigational medication  
− Any treatment designed to increase dystrophin expression (eg, Translarna™, 
EXONDYS 51, VILTEPSO™) 
8. Has received a live virus vaccine within 
 or inactive vaccine within 
 of 
the Day 1 visit or expects to receive a vaccination during the 
 after Day 1. 
9. Has abnormal laboratory values considered clinically significant including but not limited 
to: 
10. Has known hypersensitivity to delandistrogene moxeparvovec or any excipients of 
delandistrogene moxeparvovec. 
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11. Family does not want to disclose subject’s study participation with general 
practitioner/primary care physician and other medical providers. 
12. In the opinion of the Investigator, the subject is not likely to be compliant with the study 
protocol. 
8.3. 
Screen Failures 
Screen failures are defined as subjects who consent to participate in the clinical study but are not 
subsequently randomly assigned to study drug. A minimal set of screen failure information 
including demography, screen failure details, eligibility criteria, and any SAE information are 
required to ensure transparent reporting of screen failure subjects. 
 
 
 
 
Individuals who do not meet the criteria for participation in this study (screen failure) may be 
re-screened at the Investigator’s discretion with Sponsor approval. 
8.4. 
Completion of a Subject’s Participation in the Study 
Subjects will be considered to have completed their participation in the study after they have 
completed the Part 2 Week 52/early termination visit or have withdrawn from the study. 
8.5. 
Subject Withdrawal Criteria 
Any subject can decide to withdraw from study participation at any time for any reason. 
A subject who withdraws prior to dosing may be replaced at the discretion of the Sponsor. 
In addition, the Sponsor may decide to stop the study participation of any subject as deemed 
necessary. The Investigator may also stop the study participation of any subject at any time. 
Reasons for withdrawal from the study include, but are not limited to: 
• The subject or parent(s)/legal guardian(s) withdraws consent. 
• Prior to randomization and dosing it is determined that the subject was erroneously 
included in the study (ie, was found to not have met the eligibility criteria). 
• The subject is unable to comply with the requirements of the protocol. 
• The subject participates in another investigational study without prior written 
authorization of the Sponsor. 
The Investigator or study staff will document the reason(s) for withdrawal on the electronic case 
report form (eCRF). If withdrawn subjects received study drug, every effort should be made to 
request that the subject allow follow-up for safety purposes. 
Subjects who withdraw from the study must return the wearable device. 
Subjects who have received study drug and withdraw from the study but do not withdraw 
consent will be asked to continue telephone calls to collect AEs and concomitant medications 
and have blood collected for laboratory assessments according to Section 2.3 
 
 after infusion (if subjects withdraw within this window), and then for 
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safety laboratory assessments approximately 
 starting from the date 
of the last safety laboratory assessment before withdrawal. For this study, safety laboratory 
assessments include the following: electrolytes, troponin, liver function, hematology, high-
sensitivity C-reactive protein (hsCRP) and complement, renal function, and urinalysis (see 
Section 10.4.6.1 for a list of analytes associated with each parameter).  
8.6. 
Subject Lost To Follow-up 
Every effort, as allowed by local and national law, will be made by the Investigator to contact the 
subject before the subject is declared lost to follow-up. These efforts may include but are not 
limited to the following: 
• Attempt to contact the subject (or if applicable, the legal guardian who signed the 
informed consent on behalf of the subject) with at least 3 telephone calls to all 
telephone numbers for subject and other listed contacts (including in the evening and 
on weekends) and reschedule the missed visit as soon as possible and counsel the 
subject (or if applicable, the legal guardian who signed the informed consent on 
behalf of the subject) on the importance of maintaining the assigned visit schedule 
and ascertain whether or not the subject wishes to continue in the study. 
• Call the primary care physician/general practitioner, referring specialist, and/or other 
listed physicians for more recent locator information, date of last office visit, or to 
determine mortality status. 
• Send email and follow-up with mailing certified letters (return receipt requested) to 
all known subject addresses (or local equivalent methods) and all listed contacts 
(eg, relatives, friends, neighbors). 
• Review subject’s records and medical notes for any details of a hospitalization, 
doctor’s visit, or other procedure that may indicate the status of the subject. 
• Check local, regional, and national public records to locate subject or search for 
mortality status in accordance with local law. 
All contact attempts should be documented in the subject’s medical record. Once the site has 
exhausted and documented these actions, the subject will be considered to have withdrawn from 
the study. 
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9. 
STUDY TREATMENT  
9.1. 
Description of Study Drug 
Delandistrogene moxeparvovec is supplied as a sterile, single use, frozen liquid for IV infusion. 
The frozen drug product must be thawed prior to the clinical administration. Refer to the study-
specific Pharmacy Manual for further details. 
9.1.1. 
Package and Labeling 
Please refer to the study-specific Pharmacy Manual for information on packaging and dosage 
preparation instructions. 
9.1.2. 
Study Drug Preparation 
Please refer to the study-specific Pharmacy Manual for dosage preparation instructions. 
9.1.3. 
Storage 
Delandistrogene moxeparvovec must be stored at ≤ -60˚C. 
Study drug must be stored in an access controlled, locked room with appropriate temperature 
recording, controls, and monitoring. 
Details for storage can be found in the study-specific Pharmacy Manual. 
9.2. 
Study Treatment Administered 
Subjects will be randomized in a 1:1 ratio by the IRT to one of the following treatment groups: 
• Delandistrogene moxeparvovec (1.33 × 1014 vg/kg) by single IV infusion 
• Placebo (saline, 0.9% sodium chloride solution) by single IV infusion 
As required by the inclusion criterion, all subjects will be on a stable daily dose of oral 
corticosteroids for at least 12 weeks before the Screening visit, as detailed in Section 9.5.1. The 
day before the infusion (delandistrogene moxeparvovec or placebo), the subject will be started 
on additional steroid for immunosuppression and will continue at this level for at least 60 days 
after the infusion (see Section 9.5.1.1). Following these 60 days, subjects may be tapered off of 
the added steroid and return to their baseline dose of corticosteroids for DMD and will remain on 
their stable dose (except for modifications to accommodate changes in weight) through the 
remainder of the study (see Section 9.5.1.2). 
On Day 1, delandistrogene moxeparvovec or placebo administration will be through a peripheral 
limb vein and performed according to the Administration Instructions (or Manual). 
 
 
 A topical anesthetic cream (eg, lidocaine 2.5%, prilocaine 2.5%, LMX4 cream) 
may be applied to the skin prior to insertion of the IV catheter for infusions per site and subject 
preference. Prior to infusion, the IV catheter should be checked to confirm if it is within the vein 
and the IV flows well (is not interstitial).  
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9.3. 
Randomization and Blinding 
9.3.1. 
Randomization 
Subjects will be randomized in a 1:1 ratio by the IRT to receive either delandistrogene 
moxeparvovec (1.33 × 1014 vg/kg) or placebo (saline, 0.9% sodium chloride solution) by single 
IV infusion. Subjects who received delandistrogene moxeparvovec in Part 1 of the study will 
receive placebo in Part 2. Subjects who received placebo in Part 1 of the study will have the 
opportunity to receive delandistrogene moxeparvovec in Part 2. 
Randomization will be stratified 
 
 
 
.  
9.3.2. 
Blinding/Unblinding 
9.3.2.1. 
Blinded and Unblinded Personnel 
All subjects, parents/caregivers, Investigators, and site staff with the exception of the unblinded 
site pharmacist will be blinded to the treatment the subject receives (delandistrogene 
moxeparvovec or placebo). The unblinded pharmacist (or designee) will perform drug 
preparation according to the randomized treatment assigned. All documentation of study drug 
preparation will be maintained in a secure location which prevents access or disclosure to all 
blinded clinical study personnel. Refer to the study blinding plan for further details. 
9.3.2.2. 
Blinding for Muscle Biopsy Assessments 
Blinding for muscle biopsy assessments is outlined in the Biopsy Surgical and Laboratory 
Manual. 
9.3.2.3. 
Unblinding Procedures 
In the event of a medical emergency wherein the knowledge of the subject’s treatment 
assignment may influence clinical decision-making, the Investigator has the option to unblind the 
subject’s treatment assignment using the IRT system.  
The blind of the treatment may be broken only in exceptional circumstances, such as when 
knowledge of the study treatment is essential for management of a subject’s medical condition or 
AE. If time permits, the Investigator should contact the unblinded CRO Medical Director before 
unblinding the subject. If time does not permit, the Investigator may authorize breaking of the 
blind and then notify the unblinded CRO Medical Director. The study drug information should 
be disclosed only to personnel who need the information for the medical care of the subject. If 
the study treatment is unblinded, the subject number, time, date, and reason for unblinding must 
be recorded in the study records. Study personnel who were unblinded should be identified. 
The reasons for any unblinding must be noted in the source documentation. The Investigator 
must not disclose information about treatment assignment to anyone aside from specific 
individuals who need the information because of their direct involvement in subject care. 
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Regulatory authorities and/or the IRB/IEC may request the unblinding of data from subjects at 
any time. 
9.3.2.4. 
Data Access 
Clinical evaluators conducting the functional assessments will not have access to treatment 
assignment/pharmacy data or to laboratory data (eg, ELISA, 
 GGT, etc.) during 
this study. Blinded personnel will not have access to the ELISA 
 results, except for 
the Part 1 screening AAVrh74 ELISA results for eligibility, as post-infusion results from these 
tests may be unblinding. 
9.4. 
Treatment Compliance 
Delandistrogene moxeparvovec or placebo will be administered once by IV infusion under the 
direct supervision of trained study staff.  
The study staff will maintain a record of the dispensing and administration of study drug for each 
subject via an accountability record or equivalent document.  
Accurate recording of study drug administration will be made in the appropriate section of the 
subject’s eCRF and source documents. 
9.5. 
Prior and Concomitant Medications, Physiotherapeutic 
Interventions, and Lifestyle Considerations 
During Screening, the subject’s medical history will be collected. This will include all 
medications taken within 30 days of the initial Screening visit/ICF signature. If available, 
previous NSAA scores within 12 months of Screening will be recorded on the appropriate CRF. 
All concomitant medications (including over-the-counter or prescription medicines, vitamins, 
and/or herbal supplements), occupational therapy, and physiotherapeutic interventions will be 
recorded on the eCRF from the time of informed consent/assent until the final study visit.  
9.5.1. 
Corticosteroids 
Subjects must be on a stable daily dose of oral corticosteroids for at least 12 weeks before the 
initial Screening visit, with the dose remaining constant (except for modifications to 
accommodate changes in weight) throughout the study. All changes to corticosteroid type, 
dosing frequency, the dates of start and end of corticosteroid dosage, and dosage will be recorded 
in the subject’s source documents and on the eCRF. 
9.5.1.1. 
Pre-infusion Immunosuppressants 
The day before the infusion (delandistrogene moxeparvovec or placebo), subjects will begin 
additional glucocorticoid (prednisone equivalent) for immunosuppression, in addition to their 
baseline stable oral corticosteroids for DMD. Subjects on baseline daily corticosteroid dosing 
for their DMD will take their usual DMD corticosteroid dose IN ADDITION to the added 
1 mg/kg/day immunosuppressive dose. The 1 mg/kg/day dosing will be followed up to a total 
daily dose of 60 mg/day. 
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9.5.1.2. 
Post-infusion Immunosuppressants 
For the first 60 days following the infusion, subjects will remain on their baseline daily stable 
oral corticosteroid dose for DMD, and IN ADDITION will take 1 mg/kg/day of a glucocorticoid 
(prednisone equivalent) for immunosuppression. Earlier tapering to manage an AE may be 
permitted with Medical Monitor approval. The 1 mg/kg/day dosing will be followed up to a total 
daily dose of 60 mg/day, except for added steroids in the event of GGT increases and/or other 
clinically significant liver function abnormalities. 
Delandistrogene moxeparvovec may cause vomiting (for details, see the Investigator’s 
Brochure). If a subject cannot tolerate oral immunosuppressive glucocorticoids due to vomiting, 
then the glucocorticoids should be administered intravenously. 
Post-infusion added glucocorticoid for immunosuppression should be increased if GGT level is 
confirmed to be ≥ 150 U/L or there are other clinically significant liver function abnormalities 
following infusion. The Investigator may make subsequent adjustments to immunosuppressive 
therapy in reaction to the subsequent course of acute liver injury or other AEs. A hepatologist 
must be consulted for serious or severe elevations in hepatic biochemistries (including GGT, 
bilirubin, and ALT relative to Baseline), or for elevations that do not respond to 2 mg/kg/day or 
120 mg/day, respectively. In this situation, IV bolus steroids may be considered.  
• If the subject is on 1 mg/kg of added steroid for immunosuppression in addition to 
their DMD steroid, this dose should be increased to 2 mg/kg of added steroid for 
immunosuppression to be taken in addition to their DMD steroid. 
• If the subject is on 60 mg/day fixed dose, this should be increased to 120 mg/day. 
Subjects with normal GGT values and no signs of acute liver injury at Day 60 should be tapered 
off their immunosuppressive glucocorticoid over 2 weeks. The duration of tapering may be 
adjusted to manage AEs, per Investigator discretion, but continuation of steroids at a dose 
exceeding the baseline daily regimen beyond Day 90 should be discussed with the Medical 
Monitor. Immunosuppressive glucocorticoids in subjects with elevated GGT values and/or signs 
of acute liver injury at Day 60 should be managed as above until GGT values normalize (or are 
clearly trending toward normal) and all signs of acute liver injury resolve, at which point they 
should be tapered off their immunosuppressive glucocorticoid over 2 weeks. Once the additional 
steroids for immunosuppression have been tapered off, they should remain on their baseline daily 
steroid regimen for DMD, with any required adjustment for weight.  
Refer to Section 9.6.1.2 for the list of AESIs related to liver chemistry tests. 
9.5.2. 
Prohibited Medications 
All subjects will be asked to refrain from using concomitant medications that may interfere with 
the study objectives.  
Prohibited medications and time frames are listed below: 
 
− Gene therapy 
− Cell-based therapy (eg, stem cell transplantation) 
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− CRISPR/Cas9, or any other form of gene editing 
 
− Use of human growth factor or givinostat 
 
− Any investigational medication 
− Any treatment designed to increase dystrophin expression (eg, Translarna, 
EXONDYS 51, VILTEPSO) 
Additionally, subjects should not receive live virus vaccines within 
 or inactive vaccines 
within 
 of the Day 1 visit or expect to receive vaccination during the 
 after 
Day 1. 
9.5.3. 
Lifestyle Considerations 
9.5.3.1. 
Infection Precautions 
For at least the first 60 days following infusion, subjects will be immunosuppressed with 
glucocorticoids and they should be instructed to observe standard infection precautions. These 
include appropriate hand washing, avoidance of sick contacts or contacts of sick contacts, 
avoidance of crowded settings, and use of personal protective equipment as appropriate. 
9.6. 
Safety Monitoring 
9.6.1. 
Safety Monitoring for Liver Chemistry Tests 
Liver chemistry tests need to be monitored as specified in Section 2.3. Initial abnormal liver 
chemistry test result(s) needs to be confirmed if: 
• GGT is 
 or ALP 
 × ULN or AST or ALT 
 × Baseline excluding elevations 
due to muscle source 
Subjects with confirmed liver chemistry test results (as above) need to have their liver chemistry 
tests 
 retested 
. Frequency of retesting can decrease 
 if abnormalities 
stabilize or delandistrogene moxeparvovec has been discontinued and the subject is 
asymptomatic. 
9.6.1.1. 
Additional Investigations for Liver Function 
Subjects with confirmed abnormal liver chemistry test results (as above) are recommended to 
have the following evaluations performed:  
• Obtaining a more detailed history of symptoms and prior or concurrent diseases.  
• Obtaining a history of concomitant drug use (including nonprescription medications 
and herbal and dietary supplement preparations), alcohol use, recreational drug use, 
and special diets.  
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• Ruling out acute viral hepatitis types A, B, C, D, and E; autoimmune or alcoholic 
hepatitis; nonalcoholic steatohepatitis; hypoxic/ischemic hepatopathy; and biliary 
tract disease.  
• Consideration of other viral illnesses that have been associated with hepatitis 
(eg, Epstein-Barr virus [EBV], cytomegalovirus [CMV], Human Herpesvirus 6). 
• Obtaining a history of exposure to environmental chemical agents.  
• Additional liver evaluations, 
 
 may be performed at the discretion of 
the Investigator, in consultation with the Medical Monitor.  
As described in Section 9.5.1.2, a hepatologist must be consulted for serious or severe elevations 
in hepatic biochemistries 
 or for 
elevations that do not respond to 2 mg/kg/day or 120 mg/day, respectively. In this situation, IV 
bolus steroids may be considered.  
9.6.1.2. 
AESIs for Liver Function  
Treatment is not administered while any AESI is being evaluated or is unresolved.  
9.6.2. 
Safety Monitoring for Hypersensitivity 
Subjects must be monitored for occurrence of allergic reactions primarily via monitoring AEs as 
specified in Section 2.3. Subjects are instructed to promptly report any signs or symptoms of 
fever or constitutional symptoms that may arise during the study, and the Investigator needs to 
closely evaluate all potential causes, including concomitant illness.  
9.6.2.1. 
Additional Investigations for Hypersensitivity  
Subjects who experience significant or persistent constitutional symptoms need to be discussed 
with the Medical Monitor to determine whether additional monitoring or laboratory tests are 
required. Additional evaluations including 
 may be performed at the 
discretion of the Investigator in consultation with the Medical Monitor. 
9.6.2.2. 
AESIs for Hypersensitivity  
Treatment is not administered while any AESI is being evaluated or is unresolved.  
 
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9.6.3. 
Safety Monitoring for Immune-mediated Myositis 
Subjects must be monitored for occurrence of immune-mediated myositis by monitoring adverse 
events as specified in Section 2.3. Subjects are instructed to promptly report any new muscle 
pain, tenderness, or weakness, including dysphagia, dyspnea, or hypophonia as these may be 
symptoms of myositis and the Investigator needs to closely evaluate all potential causes, 
including concomitant illness and underlying disease.  
9.6.3.1. 
Additional Investigations for Immune-mediated Myositis  
Reports of rapidly progressing muscular weakness need to be discussed with the Medical 
Monitor to determine whether additional monitoring or laboratory tests are required.  
Additional evaluations including 
 
 
 may be performed at the discretion of the 
Investigator in consultation with the Medical Monitor. 
9.6.3.2. 
AESIs for Immune-mediated Myositis  
9.6.4. 
Safety Monitoring for Thrombotic Microangiopathy (TMA) 
Subjects must be monitored for occurrence of complement-mediated reactions primarily via 
monitoring AEs and complement levels. Subjects are instructed to promptly report any signs or 
symptoms of fever or constitutional symptoms that may arise during the study, and the 
Investigator needs to closely evaluate all potential alternative causes, including concomitant 
illness or medications. In addition to monitoring AEs, routine laboratory monitoring for 
complement-mediated reactions is performed per protocol as specified in Section 2.3, including 
complement levels (
, C3, C4, and 
). 
9.6.4.1. 
Additional Investigations for TMA 
Reports of TMA need to be discussed with the Medical Monitor to determine additional 
monitoring and laboratory testing. Additional evaluations including 
 
 
 
 
 
 may be performed at the discretion 
of the Investigator in consultation with the Medical Monitor. 
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9.6.4.2. 
AESIs for TMA 
9.6.5. 
Safety Monitoring for Platelet Count Results 
The platelet count needs to be monitored as specified in Section 2.3. Subjects who have a 
confirmed occurrence of platelets 
 need to have the following evaluations 
performed:  
9.6.5.1. 
Additional Investigations for Platelet Count  
Additional platelet evaluations for confirmed, unexplained significant platelet count reductions, 
including 
 
 
 may be performed at the discretion of the 
Investigator in consultation with the Medical Monitor. 
9.6.5.2. 
AESIs for Platelet Count  
Treatment is not administered while any AESI is being evaluated or is unresolved.  
9.6.6. 
Safety Monitoring for Rhabdomyolysis 
Rhabdomyolysis must be monitored by urine dipstick and adverse events as specified in 
Section 2.3. Subjects who have confirmed heme+ dipstick urinalysis need to be evaluated for 
urine microscopy and the following adverse events:  
 
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9.6.6.1. 
Additional Investigations for Rhabdomyolysis  
In case of rhabdomyolysis, myoglobinuria or chromaturia, subjects need to have evaluations of 
 
 
 these 
evaluations should be undertaken at the discretion of the Investigator. In addition, Investigators 
obtain a more detailed history of symptoms, preceding activity and hydration status, concomitant 
drug use, and recent or concurrent infections. Additional evaluations, including 
 may be performed at the 
discretion of the Investigator in consultation with the Medical Monitor. If acute onset or 
exacerbation of weakness is a feature of the rhabdomyolysis event, the subject is assessed for 
rapidly progressive weakness.  
9.6.6.2. 
AESIs for Rhabdomyolysis  
Treatment is not administered while any AESI is being evaluated or is unresolved.  
 
9.6.6.3. 
Risk of Rhabdomyolysis due to Anesthesia 
Participation in this study involves biopsies which may require anesthesia (Section 10.3.3). 
Investigators should be aware that patients with DMD have specific risks and requirements when 
undergoing anesthesia (American Academy of Pediatrics 2005, Birnkrant 2009, Bushby 2010). 
For example, there is an absolute contraindication against the use of depolarizing muscle 
relaxants (eg, succinylcholine, also known as suxamethonium) due to the risk of rhabdomyolysis; 
and a strong recommendation to avoid inhalational anesthetics (eg, sevoflurane, desflurane, 
enflurane, halothane, isoflurane) due to the risk of malignant hyperthermia-like reactions and 
rhabdomyolysis. There is no evidence that exposure to delandistrogene moxeparvovec affects 
these risks. For more details regarding anesthesia required during biopsies, refer to the Biopsy 
Surgical and Laboratory Manual. 
9.6.7. 
Safety Monitoring for Troponin Increased/Myocarditis  
Cardiac troponin levels need to be monitored as specified in Section 2.3. Initial cardiac troponin 
level result needs to be confirmed if:  
• Cardiac troponin levels 
 × ULN (or 
 Baseline for subjects with elevated 
baseline values)  
• Subjects with confirmed abnormal cardiac troponin levels need to have their cardiac 
troponin levels retested until the level returns to Baseline or stabilizes for at least 
. Frequency of retesting is at the discretion of the Investigator.  
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• Acute chest pain or pressure, palpitations, dyspnea after exercise, at rest or lying 
down, diaphoresis, and sudden death  
• Dizziness or syncope, edema, and vomiting, especially severe vomiting or presence of 
2 and more symptoms  
• For infants and children, irritability, vomiting, poor feeding, tachypnea, and lethargy 
9.6.7.1. 
Additional Investigations for Troponin Increased/Myocarditis  
Additional evaluations including 
 
 may be performed at the discretion of the Investigator in consultation with 
the Medical Monitor.  
9.6.7.2. 
AESIs for Troponin Increased/Myocarditis  
9.7. 
Treatment Overdose 
For this study, any dose of delandistrogene moxeparvovec above 
 
 will be considered an overdose. 
 
 In the event of an overdose, the Investigator should: 
1. Contact the unblinded CRO Medical Monitor immediately. 
2. Closely monitor the subject for any AE/SAE and laboratory abnormalities until 
resolution. 
3. Document the quantity of the excess dose on the Clinical Trial Safety Reporting Form 
and send to the Sponsor immediately. The overdose should also be entered in the eCRF. 
4. Provide appropriate medical care to the subject based on clinical judgement. 
Decisions regarding additional subject monitoring will be made by the Investigator in 
consultation with the unblinded CRO Medical Monitor based on the clinical evaluation of the 
subject. 
An overdose must be reported to the Sponsor or designee using the Clinical Trial Safety 
Reporting Form within 24 hours of the Investigator’s first knowledge of the event, even if the 
overdose does not result in an AE, according to the process for reporting SAEs (Section 11.4.1 ). 
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10. 
STUDY ASSESSMENTS 
10.1. 
Schedule of Events 
The schedule outlining the study assessments and times of assessments is shown in Section 2.3.  
10.2. 
Screening/Baseline Assessments 
10.2.1. 
Informed Consent and Assent 
Informed consent from the parent(s)/legal guardian(s) and assent from the subject (if applicable) 
to participate in this study must be obtained prior to performing any of the procedures required 
for this study. 
10.2.2. 
Demographic/Medical History 
Demographic information (eg, age, gender at birth, race, ethnicity, body weight, height, body 
mass index) and medical history will be obtained for all subjects. 
10.2.3. 
Genetic Diagnostics 
Subjects must have a definitive diagnosis of DMD prior to Screening based on documentation of 
clinical findings and prior confirmatory genetic testing using a clinical diagnostic genetic test. 
Genetic report must describe a frameshift deletion, frameshift duplication, premature stop, or 
other pathogenic variant in the DMD gene fully contained between exons 18 to 79 (inclusive) 
that is expected to lead to absence of dystrophin protein.  
a. Mutations between or including exons 1 to 17 are not eligible.  
b. In-frame deletions, in-frame duplications, and variants of uncertain significance 
(“VUS”) are not eligible.  
c. Mutations that are fully contained within exon 45 (inclusive) are not eligible. 
10.3. 
Efficacy Assessments 
10.3.1. 
Functional Assessments 
Every effort must be made to have each subject assessed by the same clinical evaluator for 
physical functional assessments (NSAA and timed-function tests) throughout the entire study. 
Functional assessments should be scheduled in the morning and should be the first assessments 
done during a specific visit. As NSAA is the primary outcome measure, it is to be performed 
first, followed by the timed-functional tests. Physical functional assessments are to be performed 
 throughout the study. Every effort 
should be made for the same assessor to perform the assessments throughout the study for a 
subject. 
If assessments that would impact the primary and/or secondary objectives cannot be performed 
due to events not reasonably foreseen for a period of time longer than 
, these assessments 
may be performed remotely where applicable. The subject should return to the clinic as soon as 
possible to perform the assessment in person, unless 
 of the next protocol 
scheduled assessment as applicable. 
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Functional assessments will be administered at the time points indicated in Section 2.3.  
Refer to the Clinical Evaluator Manual for additional information. 
10.3.1.1. North Star Ambulatory Assessment 
The NSAA is a clinician-administered scale that rates performance on various functional 
activities (Mazzone 2010). It was designed to be used in boys with DMD who are able to stand, 
and it has been used in DMD boys of this study’s age range (≥ 4 and < 8 years) (Connolly 2013, 
Mercuri 2016). 
During this assessment, subjects perform 17 different functional activities, including the 
10MWR, rising from a sit to a stand, standing on 1 leg, climbing a box step, descending a box 
step, rising from lying to sitting, rising from the floor, lifting head off floor, standing on heels, 
and jumping. 
Subjects will be graded as follows: 2 = normal, no obvious modification of activity; 1 = modified 
method but achieves goal independent of physical assistance from another; and 0 = unable to 
achieve goal independently. 
Details on administration of the NSAA are provided in the Clinical Evaluator Manual. 
Two NSAA scores will be collected 
 at Baseline, 
 at Week 52 
in Part 1, 
.  
10.3.1.1.1. Time to Rise from the Floor 
The time to rise from the floor test is part of the NSAA (item 12) and quantifies the time required 
for the subject to stand in an upright position with arms by sides, starting from the supine 
position with arms by sides (Henricson 2013). The time required for the subject to complete the 
task will be recorded during the NSAA administration. As with NSAA, the time to rise from the 
floor will be collected 
. 
10.3.1.1.2. 10-Meter Walk/Run 
The timed 10MWR is part of the NSAA (item 17) and quantifies the time required for the subject 
to run or walk 10 meters (on a straight walkway) from a standing position (McDonald 2013). 
The subject is encouraged to run past the 10-meter mark. The time required for the subject to 
cover the distance will be recorded during the NSAA administration. As with NSAA, timed 
10MWR will be collected 
. 
10.3.1.2. Time to Ascend 4 Steps 
The timed 4-step test quantifies the time required for the subject to ascend 4 standard steps (each 
step 6 inches in height) (Bushby 2011). The time required for the subject to climb up 4 standard-
sized steps will be recorded. 
10.3.1.3. 100-Meter Walk/Run 
The 100MWR quantifies the time required for the subject to run or walk 100 meters (on a 
straight walkway) from a standing position (Alfano 2017). The subject is encouraged to run past 
the 100-meter mark. The time required for the subject to cover the distance will be recorded. 
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10.3.2. 
Wearable Device  
Subjects will be provided with a wearable device to collect daily physical activities. The purpose 
of the wearable device is to accurately measure the movement and activity levels of the subject 
during normal daily living, outside of investigational site visits. 
 
 As the wearable device battery requires recharging daily 
after use, the sensors will not be worn at night. Site personnel, the subject, and parents/caregivers 
will be trained on the correct use of the device. Detailed user instructions are provided in the 
Wearable Investigator Manual. 
During the Pre-infusion Period, subjects should attempt to wear the device 
 
 to capture baseline values. During the Follow-up Period, subjects should attempt to 
wear the device 
 
. 
The wearable device will not be worn during clinic visits, but subjects will resume use 
immediately following completion of in-clinic tests. Subjects must return the wearable device in 
the event of screen failure, early termination, or after study completion. Refer to the Wearable 
Investigator Manual for additional information. 
10.3.3. 
Delandistrogene Moxeparvovec Dystrophin Expression 
 
 
 
 
 
 
 
The biopsy sample will be used to quantify delandistrogene moxeparvovec dystrophin protein 
expression by Sarepta’s western blot adjusted for muscle content, 
 
. Refer to the Biopsy Surgical and Laboratory Manual for additional details 
on the handling and processing of biopsy tissues.  
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10.3.6.1. Patient-Reported Outcomes Measurement Information System 
A subset of subjects based on regional availability will complete the PROMIS measures; 
participating countries will be outlined in the Study Operations Manual. 
PROMIS is a family of instruments developed and validated to assess health-related quality of 
life (PROMIS 2018, Bevans 2010). PROMIS measures have been developed in alignment with 
the Food and Drug Administration’s methodological standards for the assessment of 
patient-reported outcomes (Bevans 2010, FDA 2018) and are comprised of person-centered 
items that evaluate and monitor physical, mental, and social health in adults and children. 
Specific measures for child outcomes in this study will include the following proxy measures: 
• PROMIS Parent Proxy Item Bank V2.0 - Mobility - (23 items) 
• PROMIS Parent Proxy SF V2.0 – Upper Extremity – Short Form 8a (8 items) 
 
If a subject turns 8 years old within the study period, the following Pediatric PROMIS measures 
will also be administered and completed by the subject. The parent/caregiver will continue to 
complete the proxy measure. 
• PROMIS Pediatric Item Bank V2.0 - Mobility (24 items) 
• PROMIS Pediatric Item Bank V2.0 - Upper Extremity - Short Form 8a (8 items) 
 
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10.4. 
Safety Assessments 
10.4.1. 
Adverse Events 
The collection of AEs is detailed in Section 11.2. 
10.4.2. 
Demographic/Medical History 
Demographic data and medical history will be collected at the Screening visit. 
10.4.3. 
Vital Signs Measurements, Weight, and Height 
Vital sign measurements (including blood pressure, heart rate, respiratory rate, and 
oral/tympanic/axillary temperature), height and weight will be obtained at the time points 
specified in Section 2.3. 
During the study, vital signs will be collected from the contralateral arm from which the blood 
samples are collected. On Day 1, vital signs will be measured at 
 minutes prior to the 
start of infusion and at the following timepoints after the start of infusion: 
All vital sign measurements will be performed after the subject has remained inactive and supine 
for at least 5 minutes. Pulse rate and respiratory rate will be measured over 1 minute.  
When vital sign assessments are scheduled to be collected at the same time as blood draws, the 
vital signs will be measured prior to, but as close to, the scheduled time of the blood draw as 
possible.  
Temperature will be recorded in degrees Celsius; weight is to be recorded in kilograms, and 
height and ulnar length is to be recorded in centimeters.  
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10.4.4. 
Physical Examination 
A full or brief (symptom-directed) physical examination will be performed by the Investigator or 
qualified study staff at the time points specified in Section 2.3.  
Full physical examinations will include examination of general appearance, head, ears, eyes, 
nose, throat (HEENT), heart, chest (respiratory), abdomen (gastrointestinal), skin, lymph nodes, 
extremities, and the musculoskeletal and neurological systems.  
A brief physical examination will include examination of general appearance, HEENT, heart, 
chest, abdomen, and skin. 
10.4.5. 
Electrocardiograms and Echocardiograms 
A 12-lead ECG will be obtained in triplicate at the time points specified in Section 2.3 using an 
ECG machine that automatically calculates the heart rate and measures PR, QRS, and QT 
intervals. All ECGs should be performed at a consistent time of day throughout the study and 
before any invasive procedures (eg, blood sampling, study drug infusion, or biopsy). All ECGs 
should be performed only after the subject is in the supine position, resting, and quiet for 
approximately 15 minutes. On Day 1, triplicate ECGs will be taken both before and following 
the end of the infusion. The Investigator or designee will review the ECG results and determine 
if the findings are clinically significant. The Day 1 pre-infusion review should be completed and 
documented prior to study drug infusion. 
A standard 2-dimensional ECHO will be obtained at the time points specified in Section 2.3. 
Echocardiograms are to be performed at a consistent time of day for each assessment throughout 
the study and before any invasive procedures (eg, blood sampling, study drug infusion, or 
biopsy). The ECHO will be reviewed and interpreted by local medically qualified personnel. Left 
ventricular ejection fraction will be noted.  
10.4.6. 
Laboratory Assessments 
10.4.6.1. Routine Clinical Laboratory Tests 
The following routine clinical laboratory tests will be performed at the time points specified in 
Section 2.3. Results will be processed according to the Laboratory Manual provided and 
analyzed by a central laboratory. If local regulations restrict the blood volume further than what 
is outlined in the Investigator’s Laboratory Manual, the Investigator should consult with the 
Medical Monitor in order to determine prioritization.  
Where applicable, 
 may be performed remotely 
(Section 2.3 and Section 10.3.1). This is intended to reduce study burden while maintaining 
ongoing in-person surveillance by the study site. Detailed instructions for remote visits will be 
provided in the Investigator’s Laboratory Manual. 
If hepatic and platelet monitoring laboratories scheduled within the first 
 are unable to 
be performed at the central laboratory due to events not reasonably foreseen, these assessments 
may be performed remotely and/or at local laboratories where applicable. In addition, if any 
laboratory assessments that impact AE management cannot be performed at the central 
laboratory, these assessments may be done locally at the discretion of the caregiver. 
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Note: At 
, samples will be collected 
. 
Electrolytes: 
Sodium, chloride, potassium, carbon dioxide  
Troponin: 
Troponin I 
Glucose: 
Serum glucose 
 
 
Liver Function: 
Total and direct bilirubin, alkaline phosphatase, amylase, ALT, 
AST, GGT, lactate dehydrogenase, albumin. Additionally, GLDH 
is collected for research use only. 
Hematology: 
Red blood cells, total white blood cells, hemoglobin, hematocrit, 
neutrophils, lymphocytes, monocytes, eosinophils, basophils, 
platelets, prothrombin time, partial thromboplastin time, INR  
hsCRP and complement: 
hsCRP and complement (
, C3, C4, 
) 
Renal function: 
Creatinine, blood urea nitrogen, and serum cystatin C  
Urinalysis: 
pH, specific gravity, protein, glucose, ketones, hemoglobin 
Any value outside of the reference ranges for the laboratory performing the test will be flagged 
in the laboratory results. The Investigator or designee will determine whether abnormal results 
are clinically significant. 
A laboratory abnormality (Section 11.2.1) deemed clinically significant by the Investigator or 
designee should be recorded as an AE. A clinically significant abnormality is generally an 
abnormality, confirmed by repeat testing, that is changed sufficiently from Screening/Baseline so 
that, in the judgment of the Investigator, a change in management is warranted. 
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Sample Collection 
 
 
 
 
For sampling procedures, storage conditions, and shipment instructions, see the laboratory 
manual. 
 samples are to be stored until they are no longer needed or until they are exhausted. 
However, the 
 storage period will be in accordance with the IRB/EC-approved Informed 
Consent Form and applicable laws (eg, health authority requirements). 
10.4.6.3. Virus Serology 
Blood samples will be collected at the Screening visit for analysis of HIV, hepatitis B, and 
anti-hepatitis C virus testing. Hepatitis B results will be based on the United States, Department 
of Health & Human Services, Centers for Disease Control and Prevention, Interpretation of 
Hepatitis B Serologic Test Results (Department of Health and Human Services 2005).  
Blood samples will be collected at the Baseline visit for analysis of EBV, CMV, parvovirus B19, 
varicella zoster virus, HH6, hepatitis A, and hepatitis E. 
10.4.6.4. Concomitant Medications and Physiotherapeutic Interventions 
New and ongoing concomitant medications and procedures, changes in dosage of concomitant 
medications, and concomitant therapies, including physiotherapeutic interventions, will be 
reviewed, and recorded at each visit from the time the subject signs the informed consent/assent 
form through the end of the study. See Section 9.5 for details of permitted concomitant 
medications. 
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10.4.8. 
Use/Analysis of Muscle Biopsies 
In addition to the analyses listed in Section 10.3.3 and Section 10.3.4, the use/analysis of muscle 
biopsies is outlined below: 
• The results of muscle biopsy analyses may be reported in the clinical study report or 
in a separate study summary. 
• The Sponsor will store the muscle biopsy samples in a secure storage space with 
adequate measures to protect confidentiality. 
• All samples obtained will be stored for 
 and maintained for 
up to 
 following the end of the study or in accordance with local regulation if 
permitted by the informed consent/assent form.  
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11. 
ADVERSE EVENTS AND OTHER SAFETY INFORMATION 
11.1. 
Definitions  
11.1.1. 
Adverse Event 
An AE is any untoward medical occurrence in a clinical study subject that does not necessarily 
have a causal relationship with the study drug. An AE can, therefore, be any unfavorable and 
unintended sign (including an abnormal laboratory finding, for example), symptom, or disease 
temporally associated with the use of a study drug, whether or not considered related to the study 
drug. 
Adverse events include: 
• Symptoms described by the subject or signs observed by the Investigator or medical 
staff 
• The onset of new illness and the exacerbation of pre-existing medical conditions 
• Test abnormalities (laboratory tests, ECG, etc.) deemed clinically significant  
Abnormalities present at Screening will be collected as part of medical history and are 
considered AEs only if they re-occur after resolution or worsen during the AE collection period. 
11.1.2. 
Serious Adverse Event 
A Serious Adverse Event (SAE) is an untoward medical occurrence that at any dose:  
• Results in death 
• Is life threatening  
Note: The term “life-threatening” in the definition of “serious” refers to an event in 
which the subject was at risk of death at the time of the event; it does not refer to an 
event which hypothetically might have caused death if it were more severe.  
• Requires inpatient hospitalization or prolongation of existing hospitalization ** 
• Results in persistent or significant disability/incapacity 
• Is a congenital anomaly/birth defect 
• Is a medically important event or reaction 
Note: Medical and scientific judgment should be exercised in deciding whether an 
event should be reported as an SAE 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 subject or may require intervention to prevent 
one of the other outcomes listed in the definition above. These should also usually be 
considered serious.  
**Sponsor Note on Hospitalizations** 

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The following types of hospitalizations do not meet the SAE criteria defined above: 
• Hospitalizations that are part of the study procedures unless the hospitalization is 
prolonged (based on the judgment of the Investigator) due to an AE 
• Elective or pre-planned hospitalizations for a pre-existing condition that is unrelated 
to the indication under study and has not worsened since signing the informed 
consent form (documented as medical history on the eCRF if applicable per protocol) 
11.1.3. 
Suspected Unexpected Serious Adverse Reactions 
A Suspected Unexpected Serious Adverse Reactions (SUSAR) is an AE or suspected adverse 
reaction considered “unexpected” if it is not listed in the Investigator’s Brochure or is not listed 
at the specificity or severity that has been observed; or, if an Investigator’s Brochure is not 
required or available, is not consistent with the risk information described in the general 
investigational plan or elsewhere in the current application, as amended. 
11.1.4. 
Adverse Event of Special Interest 
An AESI is any AE (serious or nonserious) that is of scientific and medical concern specific to 
the Sponsor’s product or program, for which ongoing monitoring and rapid communication by 
the Investigator to the Sponsor can be appropriate. Such an event might warrant further 
investigation in order to characterize and understand it. Depending on the nature of the event, 
rapid communication by the study Sponsor to other parties (eg, regulators) might also be 
warranted. A list of AESIs is presented in Section 11.4.2.5.  
11.1.5. 
Special Situations 
A comprehensive term that encompasses safety information related to products for which global 
regulations require collection, evaluation, and/or reporting to regulatory authorities.  
Special situations include, but are not limited to, reports of: 
• Overdose: Whether accidental or intentional, with or without any AEs. 
Administration of a quantity of a study drug given per administration or cumulatively, 
which is above the maximum recommended dose according to the authorized product 
information. See Section 9.7 for further details. 
• Medication error: Actual and potential, including product confusion. An unintended 
failure in the study drug treatment process that leads to, or has the potential to lead to, 
harm to the subject (see EMA-PRAC Good Practice Guide on Recording, Coding, 
Reporting and Assessment of Medication Errors, 23 October 2015). 
• Product misuse: Situations where a study drug is intentionally and inappropriately 
used not in accordance with the terms of the Investigator’s Brochure. 
• Product abuse: Abuse of a study drug that is persistent or sporadic; intentional 
excessive use of study drug, which is accompanied by harmful physical or 
psychological effects [DIR 2001/83/EC Art 1(16)]. 

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• Occupational exposure: For the purpose of reporting cases of suspected adverse 
reactions, an exposure to a study drug as a result of one’s professional or non-
professional occupation. 
• Drug interactions: Occur when 2 or more drugs react with each other. Drug-drug 
interaction may cause an unexpected side effect experience. 
• Unexpected benefit: Unanticipated desirable and beneficial effects resulting from 
a medical treatment aside from the use for which it has been given. 
• Accidental exposure: Inadvertent exposure to the medicinal product by someone other 
than the subject. 
11.2. 
Collection of Adverse Events 
All AEs, regardless of the source of identification (eg, physical examination, laboratory 
assessment, ECG, reported by subject), must be collected, and documented in the eCRF.  
All AEs will be collected and recorded from the time of informed consent/assent through the last 
follow-up visit.  
All AEs (including AESIs and special situations) and SAEs experienced by a subject, 
irrespective of the suspected causality, will be monitored until the AE or SAE has resolved, any 
abnormal laboratory values have returned to stabilization, baseline status, and there is a 
satisfactory explanation for the changes observed, completion of the subject’s study 
participation, or study termination, whichever occurs first. 
Concomitant illnesses that existed before entry into the study will not be considered AEs unless 
the illness worsens during the treatment period. Pre-existing conditions must be recorded in the 
eCRF, as well as on the Clinical Trial Safety Reporting Form’s medical history section. 
For subjects who are prematurely discontinued from the study (Section 8.5), AEs should 
continue to be recorded at least until 28 days after the last study drug administration. 
For subjects who are found to be ineligible for the study during the Pre-infusion Period and are 
not enrolled (ie, screen failures), only SAEs (Section 11.1.2) will be reported (Section 11.4.1). 
If, at any time after the subject has completed participation in the study (Section 8.4), the 
Investigator or study staff become aware of an SAE that the Investigator assesses as related to 
the study drug (Section 11.3.1) or related to a study procedure (Section 11.3.2), then the event 
and any known details must be reported promptly to the Sponsor, no later than within 24 hours of 
awareness. 
11.2.1. 
Clinical Laboratory Abnormalities 
A laboratory abnormality deemed clinically significant (Section 10.4.6.1) by the Investigator 
should be recorded as an AE. A clinically significant abnormality is generally an abnormality, 
that is changed sufficiently from Screening/Baseline in the judgment of the Investigator. If an 
abnormal laboratory value or vital sign is associated with clinical signs and/or symptoms, the 
sign or symptom should be reported as an AE or SAE (if it meets seriousness criteria), and the 
associated laboratory value or vital sign should be considered additional information that must be 
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only the diagnosis needs to be recorded on the Clinical Trial Safety Reporting Form and eCRF. 
Abnormal laboratory values assessed as not clinically significant should be documented as such 
in the source document. 
11.2.2. 
Disease Progression 
Disease progression per se is not to be reported as an AE in this study. If AEs/SAEs occur in 
relation to disease progression, the AEs/SAEs must be reported per the AE/SAE reporting 
requirements described in this section.  
11.3. 
Classification of Adverse Events 
All AEs, whether serious or nonserious, will be classified by the Investigator according to the 
following rules and definitions. 
11.3.1. 
Relationship to Study Drug 
For each AE, the Investigator will determine whether there is a reasonable likelihood that the AE 
may have been caused by the study drug, according to the categories below: 
Unrelated: 
There is no reasonable possibility that the event is related to 
the study drug. 
Related: 
There is a reasonable possibility that the event is related to the 
study drug.  
11.3.2. 
Relationship to Study Procedures 
For each AE, the Investigator will determine whether there is a reasonable possibility that the AE 
may have been caused by the study procedures, according to the categories below: 
Unrelated: 
There is no reasonable possibility that the event is related to 
the study procedures. 
Related: 
There is a reasonable possibility that the event is related to the 
study procedures.  
11.3.3. 
Relationship to Underlying Disease 
For each AE, the Investigator will determine whether there is a reasonable possibility that the AE 
may be related to the underlying disease, according to the categories below: 
Unrelated: 
There is no reasonable possibility that the event is related to 
the underlying disease. 
Related: 
There is a reasonable possibility that the event is related to the 
underlying disease. 

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11.3.4. 
Severity of Adverse Events 
The Investigator will assess the severity of all AEs using the National Cancer Institute Common 
Terminology Criteria for Adverse Events (CTCAE) scale, Version 5.0. Adverse events not listed 
in the CTCAE will be assessed according to the following scale. 
Grade 1 Mild: asymptomatic or mild symptoms; clinical or diagnostic observations only; 
intervention not indicated 
Grade 2 Moderate: minimal, local, or noninvasive intervention indicated; limiting age-
appropriate instrumental ADL 
Grade 3 Severe or medically significant but not immediately life-threatening: hospitalization 
or prolongation of hospitalization indicated; disabling; limiting self-care ADL 
Grade 4 Life-threatening consequences: urgent intervention indicated 
Grade 5 Death related to AE 
Note that severity is not the same as “seriousness,” which is defined in Section 11.1.2 and which 
serves as a guide for defining regulatory reporting obligations.  
In addition, laboratory or vital signs-based AEs that are defined as Grade 4 in the CTCAE solely 
by laboratory or vital sign measurements are not automatically clinically life-threatening; the 
Investigator must make this clinical assessment regardless of grade. All other AEs of Grade 4 
(life-threatening) or Grade 5 (fatal) severity are to be reported as SAEs (Section 11.4.1). 
11.3.5. 
Outcomes of Adverse Events 
“Outcome” describes the status of the AE. The Investigator will provide information regarding 
the subject outcome for each AE. Outcome categories will include “recovered”, “recovered with 
sequelae”, “not recovered”, “fatal”, and “unknown.” 
11.3.6. 
Action Taken Regarding the Study Drug 
The Investigator will provide information regarding the action taken with respect to the study 
treatment in response to the AE. Categories for action taken regarding study treatment will 
include “none” and “drug interrupted.” 
11.3.7. 
Expectedness of Adverse Events 
The expectedness of all AEs will be determined by the Sponsor according to the most recent 
version of the Reference Safety Information (RSI) section of the Investigator’s Brochure for 
delandistrogene moxeparvovec. Expectedness is defined as whether an AE is listed or not listed 
in the RSI section of the Investigator’s Brochure. 
11.4. 
Recording of Adverse Events 
All AEs, from the signing of informed consent/assent through the last Follow-up visit, will be 
recorded in each enrolled subject’s eCRF. All SAEs and other safety information, such as that 
pertaining to special situations (Section 11.1.5) including specified AESIs (Section 11.4.2.5) will 
also be recorded on the Clinical Trial Safety Reporting Form and reported to the Sponsor via 
email to 
 within 24 hours of awareness. Electronic reporting may be 
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configured for this study; when configured and deployed, the Sponsor will receive safety 
information recorded in the subjects’ eCRF via a 
. 
Information recorded should include the following: a concise description of the AE; date of event 
onset and resolution; determination of seriousness, severity, corrective treatment, outcome, and 
relationship to study drug, study procedure, and underlying disease; any action taken, relevant 
laboratory results, and diagnostic tests. Resolution occurs when the subject has returned to the 
Baseline state of health, or when further improvement or worsening of the AE is not expected. 
If a diagnosis is known at the time of reporting, the diagnosis should be recorded as an AE, 
rather than its signs and symptoms or isolated laboratory abnormalities related to that diagnosis. 
Several symptoms or laboratory results that are associated with the same diagnosis can thus be 
part of the same AE. A medical or surgical procedure is not an AE; rather, the condition leading 
to the procedure should be recorded as the AE. However, if a constellation of signs and/or 
symptoms cannot be medically characterized as a single diagnosis or syndrome, each individual 
event should be recorded as an AE or SAE on the eCRF. If a diagnosis is subsequently 
established, it should be reported as follow-up and should replace the individual signs and/or 
symptoms as the event term on the eCRF. 
Similarly, death is not an AE, but rather, the outcome of the AE(s) that resulted in death. All 
causes of death are SAEs. In the event of death, every effort should be made to obtain a death 
certificate and if possible, an autopsy report. If the cause of death is unknown, the best MedDRA 
Preferred Term to describe the death will be recorded as the AE. 
Any SAE assessed as related to the study drug, occurring after the subject completes the study, 
should be recorded on a Clinical Trial Safety Reporting Form, and reported as per the 
instructions for SAEs provided immediately below. 
11.4.1. 
Reporting Serious Adverse Events 
11.4.1.1. Serious Adverse Events 
All SAEs, from the signing of informed consent/assent through the last Follow-up visit, 
including SAEs from screen failures, will be reported to the Sponsor or designee within 24 hours 
of the Investigator’s first knowledge of the event. 
Email: 
        US Fax: 
           EU Fax: 
 
Serious AEs should be communicated on the Clinical Trial Safety Reporting Form as follows: 
The initial report must be completed as soon as possible, including details of the current illness 
and SAE, and an assessment of the causal relationship between the event and the study drug(s). 
Information not available at the time of the initial report (eg, an end date for the AE, laboratory 
values received after the report, or hospital discharge summary) must be provided to the Sponsor 
during Follow-up. All follow-up information must be reported in the same timelines as the initial 
information. At any time after completion of the AE reporting period (ie, after last Follow-up 
visit), if an Investigator becomes aware of an SAE that is suspected by the Investigator to be 
related to study drug, the event must be reported to the Sponsor or designee. 
The Sponsor may request follow-up information on a PV query form or send targeted 
questionnaires to collect additional information. 
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11.4.1.2. Suspected Unexpected Serious Adverse Reactions 
All SUSARs will be handled by appropriate Sponsor (or designee) personnel and reported within 
the required timelines, in an unblinded fashion, to regulatory authorities and the IRB/IEC, per 
ICH and local regulations and/or the requirements of the concerned competent authorities.  
11.4.2. 
Reporting Special Situations 
Regardless of whether or not there is an associated AE, special situations will be collected as part 
of the study drug dosing information and/or as a protocol violation, as required. 
Any AEs associated with the special situations should be recorded on the AE eCRF with the 
diagnosis of the AE. 
11.4.2.1. Overdose 
Refer to Section 9.7 for the definition of treatment overdose. An overdose is not an AE. An 
overdose will be reported even if it does not result in an AE. An overdose will be recorded on the 
Clinical Trial Safety Reporting Form and sent to the Sponsor or designee within 24 hours 
according to the process for reporting SAEs (Section 11.4.1). 
11.4.2.2. Medication Error 
Any medication error is to be reported to the Sponsor on the Clinical Trial Safety Reporting 
Form within 24 hours of awareness of the error even if the error does not result in an AE, 
according to the process for reporting SAEs (Section 11.4.1).  
11.4.2.3. Accidental/Occupational Exposure 
Any accidental/occupational exposure (Section 11.1.5) is to be reported to the Sponsor on the 
Clinical Trial Safety Reporting Form within 24 hours of becoming aware, according to the 
process for reporting SAEs (Section 11.4.1). 
11.4.2.4. Product Misuse/Abuse 
Any misuse/abuse (Section 11.1.5) are to be reported to the Sponsor on the Clinical Trial Safety 
Reporting Form within 24 hours of becoming aware, according to the process for reporting SAEs 
(Section 11.4.1). 
11.4.2.5. Adverse Events of Special Interest  
All AESIs are immediately reportable events, even if the events do not meet SAE criteria. This 
includes the events below that are based on laboratory abnormalities, which should be translated 
to the appropriate AE term at the time of reporting. 
All AESIs should be reported to the Sponsor or designee within 24 hours of the Investigator’s 
first knowledge of the event, whether or not the event is serious, even if the experience does not 
appear to be related to the study drug. AESIs should be reported as described above for SAEs, 
according to the process for reporting SAEs (Section 11.4.1). 
In this study, the following AEs are considered AESIs: 

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Hepatotoxicity 
Myositis 
Thrombotic microangiopathy (TMA) 
Hypersensitivity 
Thrombocytopenia 
Rhabdomyolysis 
Troponin elevations 
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11.4.3. 
Miscellaneous 
11.4.3.1. Responsibilities of the Investigator 
The responsibilities of the Investigator related to safety reporting include, but are not limited to, 
the following: 
• Monitoring and recording all AEs 
• Determining the seriousness, severity, and relationship to study drug, study 
procedure, and underlying disease for each AE 
• Determining the onset and end date of each AE 
• Providing the initial report of all SAEs, special situations, and noted AESIs to the 
Sponsor via email to 
 or designee within 24 hours of first 
knowledge.  
• Providing follow-up information on SAEs in a timely and proactive manner 
• Responding to queries regarding AEs and SAEs in a timely manner 
• Ensuring that source documentation for all AEs is accurate and complete 
• Ensuring that the study is conducted as defined in this protocol  
• Submission of safety events to the IEC/IRB according to the policies and 
requirements 
Investigators may also report improvement of pre-existing DMD conditions or unexpected 
therapeutic responses. 
11.4.3.2. Responsibilities of the Sponsor 
The responsibilities of the Sponsor related to safety reporting include, but are not limited to, the 
following: 
• Training of Investigator on AE/SAE, special situations and AESI definitions, safety 
assessments, and site obligations related to safety monitoring and reporting of 
AEs/SAEs 
• Training with regard to the accurate and legal reporting of SAEs to all applicable 
regulatory authorities, IRBs/IECs, clinical study sites, and other parties, as 
appropriate and required within the regulated timing 
• Ensuring accurate recording of AEs and SAEs, Special Situations, and AESIs 
• Submission of expedited serious, unexpected, and related AEs to regulatory 
authorities per regulatory requirements 
• Notification of blinded, unexpected and related SAEs to sites 
• Annual safety reporting to regulatory authorities and IRBs/IECs according to regional 
requirements 
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12. 
STATISTICAL CONSIDERATIONS  
12.1. 
Statistical Hypotheses 
For the primary efficacy endpoint of change in NSAA total score from Baseline to Week 52 
(Part 1), the null hypothesis is that the population means for the 2 treatments are equal and the 
alternative hypothesis is that the population means for the 2 treatments are not equal. Even 
though the alternative hypothesis is 2-sided, only superiority of delandistrogene moxeparvovec 
over placebo will be of interest.  
The statistical hypotheses for secondary efficacy endpoints can be stated in a similar manner as 
those for change in NSAA total score from Baseline to Week 52 (Part 1).  
12.2. 
Sample Size Determination 
The sample size of this study is based on the power for the primary efficacy endpoint, change in 
NSAA total score from Baseline to Week 52 (Part 1).  
 
 
 
 
 
This sample size calculation 
 
 is based on efficacy data from 
a double-blind, placebo-controlled, Phase 2 study as well as comparison against external controls 
in DMD. 
12.3. 
Analysis Populations 
For purposes of statistical analyses, the following analysis populations are defined: 
Population 
Description 
Intent-to-Treat (ITT) 
All randomized subjects (not including those enrolled under a regional 
addendum), with treatment group designated according to randomization.  
Modified Intent-to-Treat 
(mITT) 
All randomized subjects who receive study treatment (not including those 
enrolled under a regional addendum), with treatment group designated 
according to randomization. The mITT population will be the analysis 
population for efficacy endpoints. 
Safety 
All subjects who received study treatment (not including those enrolled 
under a regional addendum), with treatment group designated according 
to the treatment that they actually received.  
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12.4. 
Statistical Analyses 
This section is a summary of the planned statistical analyses of the primary and secondary 
efficacy endpoints as well as the safety analyses. Details of the statistical analyses will be 
included in the SAP, which will be developed and finalized before database lock and unblinding 
of the study data.  
12.4.1. 
Subject Disposition 
The number and percentage of subjects completing or prematurely discontinuing from the study 
will be summarized by treatment. Reasons for premature discontinuation will also be 
summarized. The analyses will be based on the mITT population. 
12.4.2. 
Demographic and Baseline Characteristics 
Demographic information and baseline characteristics including age (years), sex at birth, race, 
ethnicity, baseline height (cm), weight (kg), body mass index (kg/m2), genetic mutations, and 
prognostic factors such as baseline measures for functional assessments will be summarized by 
treatment. The analyses will be based on the mITT population. 
12.4.3. 
Concomitant Medications 
Concomitant medications will be coded by preferred term (PT) using the most recent World 
Health Organization Drug Dictionary (WHODrug) version. The number and percentage of 
subjects in the mITT population with concomitant medications will be tabulated by Anatomical 
Therapeutic Chemical classification pharmacological subgroup and WHODrug PT.  
12.4.4. 
Efficacy Analyses 
The primary endpoint and some secondary endpoints will be tested in a hierarchical manner 
using an appropriate multiple testing approach that provides strong control of the familywise 
Type 1 error rate at a 2-sided 0.05 level. The details of the testing procedure will be specified in 
the SAP.  
12.4.4.1. Analyses of Primary Efficacy Endpoint 
For the primary endpoint of change in NSAA total score from Baseline to Week 52 (Part 1), 
summary statistics will be provided by treatment group for NSAA total score at Baseline, each 
post-Baseline visit in Part 1, and for change from Baseline to each post-Baseline visit in Part 1. 
 
 
As the primary analysis, a restricted maximum likelihood-based mixed model repeated measures 
analysis will be used to compare the 2 treatment groups for change in NSAA total score from 
Baseline to Week 52 (Part 1). In this model, the response vector consists of the change in NSAA 
total score from Baseline to each post-Baseline visit in Part 1. The model will include the 
covariates of treatment group (categorical), visit (categorical), treatment group by visit 
interaction, age group at randomization, baseline NSAA total score, age group at the time of 
randomization by visit interaction, and baseline NSAA total score by visit interaction. All 
covariates will be fixed effects in this analysis.  
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An unstructured covariance matrix will be used to model the within-subject variance-covariance 
errors. If the unstructured covariance structure results in a lack of convergence, the 
heterogeneous first-order autoregressive covariance structure will be used. The Kenward-Roger 
approximation will be used to estimate the denominator degrees of freedom (Kenward 1997). 
In the primary analysis, missing data are assumed to be missing at random.  
Sensitivity analyses will be performed to assess the robustness of the primary analysis 
conclusions with respect to deviations from missing at random assumption.  
 
 
12.4.4.2. Analyses of Key Secondary Endpoints 
The following secondary endpoints will be analyzed using similar statistical methods as the 
primary endpoint, as appropriate, with details specified in the SAP: 
• Number of skills gained or improved at Week 52 (Part 1) as measured by the NSAA 
• Change in timed function tests, including the rise from the floor, the 100MWR, time 
to ascend 4 steps, and the 10MWR from Baseline to Week 52 (Part 1) 
• Change in SV95C from Baseline to Week 52 (Part 1) 
• Change in PROMIS score in Mobility domain and Upper Extremity Function domain 
from Baseline to Week 52 (Part 1) 
For the secondary endpoint of quantity of delandistrogene moxeparvovec dystrophin protein 
expression at Week 12 (Part 1) as measured by western blot of biopsied muscle tissue, summary 
statistics will be provided by treatment group for delandistrogene moxeparvovec dystrophin 
protein expression at Week 12 (Part 1). A re-randomization test will be performed to compare 
the endpoint between the 2 treatment groups.  
The superiority of delandistrogene moxeparvovec over placebo will be concluded if the test 
achieves statistical significance based on the multiplicity-adjusted testing procedure that will be 
specified in the SAP.  
12.4.5. 
Safety Analyses 
12.4.5.1. Adverse Events 
All safety analyses will be based on the safety population.  
Adverse events will be coded using the Medical Dictionary for Regulatory Activities. A TEAE 
will be defined as an AE that emerges during treatment, having been absent pre-treatment, or 
worsens relative to the pretreatment state. A drug-related TEAE will be defined as a TEAE that 
the Investigator considers related to study drug. 
Treatment-emergent adverse events and drug-related TEAEs will be summarized separately by 
treatment group by the number and percentage of subjects who reported TEAEs. Safety analyses 
for each study period will use all visits up through the last scheduled visit in the prior study 
period as baseline. For each subject and TEAE, the maximum severity for the MedDRA level 
being displayed (preferred term, High Level Term, or system organ class [SOC]) is the 
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maximum post-baseline severity observed from all associated terms mapping to that MedDRA 
level. 
Serious adverse events, and treatment-emergent SAEs separately, will be summarized by 
treatment group. 
12.4.5.2. Other Safety Assessments 
Descriptive statistics for ECG, vital signs, immunogenicity, and safety laboratory parameters will 
be generated. Summary statistics for each parameter at specific time points, as well as the change 
from Baseline to that time point (if applicable), will also be displayed. All safety data will be 
presented in the data listings. 
12.5. 
Interim Analysis 
The primary analysis of the study will be performed after all subjects have completed Part 1 or 
have withdrawn early from Part 1. No interim analysis is planned prior to the completion of 
Part 1. 
12.6. 
Data Monitoring Committee 
A program-wide independent Data Monitoring Committee (DMC) will monitor safety, efficacy, 
data quality, and the integrity of study. The activities and composition of this committee are 
outlined in the DMC Charter. 

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13. 
DATA COLLECTION, QUALITY ASSURANCE, AND 
MANAGEMENT 
13.1. 
Study Monitoring 
Before an investigational site can enter a subject into the study, a representative of the Sponsor 
will visit the investigational study site to: 
• Determine the adequacy of the facilities 
• Discuss with the Investigator(s) and other personnel their responsibilities with regard 
to protocol adherence, and the responsibilities of the Sponsor or its representatives. 
This will be documented in a Clinical Study Agreement between the Sponsor and the 
Investigator. 
The Investigator(s)/institution(s) agree to provide direct access to source data/documents 
(including electronic records, unless prohibited by local regulations) for study-related 
monitoring, audits, IRB/IEC review, and regulatory inspections. 
During the study, a monitor from the Sponsor or representative will have regular contacts with 
the investigational site, for the following: 
1. Provide information and support to the Investigator(s) 
2. Confirm that facilities remain acceptable 
3. Confirm that the investigational team is adhering to the protocol, that data are being 
accurately recorded in the case report forms, and that study drug accountability checks 
are being performed 
4. Perform source data verification. This includes a comparison of the data in the case report 
forms with the subject’s medical records at the hospital or practice, and other records 
relevant to the study. This will require direct access to all original records for each 
subject (eg, clinic charts). 
5. Record and report any protocol deviations not previously sent to the Sponsor. 
6. Confirm AEs and SAEs have been properly documented on case report forms and 
confirm any SAEs have been forwarded to the Sponsor and those SAEs that met criteria 
for reporting have been forwarded to the IRB/IEC as required. 
The monitor will be available between visits if the Investigator(s) or other staff need information 
or advice. 
13.2. 
Recording of Data 
Clinical data for this study will be captured in an electronic format. The Investigator, or 
personnel delegated by the Investigator, will perform primary data collection/perform 
assessments based on the protocol design and captured in source documentation. Source 
documents are filed at the Investigator’s site. All required study information must be recorded on 
the appropriate eCRF screens/forms. Data entered in the eCRF that are transcribed from source 
documents must be consistent with the source documents. All data must be carefully entered in a 
timely fashion to permit meaningful interpretation and study oversight. 

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13.3. 
Quality Assurance 
The eCRFs will be reviewed at regular intervals by a Clinical Monitor from the Sponsor or 
a representative of the Sponsor per the agreed-upon Clinical Monitoring Plan against the source 
documentation for identification and clarification of any discrepancies. The Investigator must 
maintain accurate documentation (source data) that supports the information entered in the 
eCRF. Automated and manual quality checks will be in place to identify discrepancies, such as 
missing data, protocol deviations, out of range data, other data inconsistencies, and compliance. 
Requests for data clarification or correction will be documented as electronic queries within the 
eCRF and for the Investigator or site staff to resolve. All changes to the eCRFs will be tracked 
in an electronic audit trail. Investigator site files will be reviewed for compliance throughout the 
study. 
Audits may be carried out by the Sponsor’s representatives, and inspections may be performed 
by IRBs/IECs or regulatory authorities before, during, or after the study. The Investigator will 
allow and assist the Sponsor’s representatives and any regulatory agency to have direct access to 
all study records, eCRFs, subject medical records, and other source documentation, study drug 
dispensing records and storage area, study facilities, and any other source documentation.  
The Investigator must make study files and data accessible to the Study Monitor, to other 
authorized representatives of the Sponsor, and to the appropriate regulatory authority inspectors. 
13.4. 
Retention of Study Documents 
At CSR completion, all eCRF data for an individual site will be provided via electronic media 
to the Investigator for retention in the Investigator site files.  
The length of storage of study documents varies by country and stage of clinical development 
in any region in the world. Therefore, no study documents, including subject records and other 
source data, will be destroyed, or moved to a new location without prior written approval from 
the Sponsor. 
If the Investigator relocates, retires, or withdraws from the clinical study for any reason, all 
records that are required to be maintained for the study are to be transferred to an agreed-upon 
designee.  
If offsite archiving is used, all records must be retrieved and made available for review at the 
time of an audit or regulatory authority inspection. 

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14. 
ETHICS AND OTHER SPECIAL REQUIREMENTS 
It is the responsibility of both the Sponsor and the Investigator(s) to ensure that this clinical study 
will be conducted in accordance with the ethical and scientific principles governing clinical 
research as set out in the Declaration of Helsinki, GCP Guidelines described in the ICH E6 (R2) 
and 21 Code of Federal Regulations parts 50, 54, 56, and 312; and applicable national 
regulations and directives such as EU Clinical Practice Directive 2005/28/EC, Regulation EU No 
536/2014, Japanese GCP Regulation, and other applicable regulatory requirements. The clinical 
study will be conducted in compliance with Pharmaceutical and Medical Device Act, and the 
Clinical Study Protocol. 
14.1. 
Institutional and Ethics Review 
Before study initiation, the protocol, Investigator’s Brochure, informed consent/assent form, 
parental ICF (for parents/legal guardians), and other relevant documents (as applicable) will be 
submitted, reviewed, and approved by the appropriate IRB/IEC and regulatory authority. 
Amendments to the protocol and all substantial changes to the study documentation will require 
IRB/IEC and regulatory authority review and approval before implementation of changes made 
to the study design, except for changes necessary to eliminate an immediate hazard to study 
subjects.  
The Investigator will promptly notify the IRB/IEC and Sponsor of any SAEs or of any other 
information that might affect the safe use of the study drug during the study according to the 
IRB/IEC requirements. The IRB approvals/IEC positive opinions and regulatory authorities’ 
approvals must be sent to the Sponsor (or designee) before initiation of the study or before an 
amendment is instituted.  
All correspondence with the IRB/IEC and regulatory authorities must be retained within the 
study regulatory files and made available for inspection. 
14.2. 
Informed Consent and Assent 
Informed consent and assent from each subject and/or parent/legal guardian must be obtained 
before any study-specific evaluations are performed. A copy of the signed informed consent 
(and assent) form will be given to the subject and/or parent/legal guardian; the Investigator will 
retain the original copies of these documents. 
The informed consent/assent documents, as prepared by the Sponsor (or designee), must be 
reviewed and approved by the IRB/IEC and regulatory authorities, as applicable, before initiation 
of the study. The informed consent document must contain the basic required elements of 
consent and additional elements, as applicable, as specified in ICH GCP E6 (R2). In the event of 
an update to the ICF/assent(s), subjects must be re-consented to the most current 
IRB/IEC-approved version of the ICF/assent(s) prior to continuation of their participation in the 
study. 
14.3. 
Compliance with the Protocol 
All processes and procedures defined in this protocol must be adhered to. Emergency departures 
from the protocol that eliminate an apparent immediate hazard to a particular subject and are 
deemed by the Investigator as crucial for the safety and well-being of that subject, may be 

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instituted for that subject only and documented as deviations. The Investigator will contact the 
Sponsor Medical Monitor as soon as possible regarding such a deviation. These departures do 
not require pre-approval by the IRB/IEC; however, the IRB/IEC and Medical Monitor must be 
notified in writing as soon as possible in accordance with the IRB/IEC policies after the 
departure has been made. 
14.4. 
Confidentiality 
All information regarding the nature of the proposed investigation that is provided to the 
Investigator by the Sponsor, the Sponsor’s designee, or the Study Monitor, with the exception of 
information that is required by law or regulations to be disclosed to the IRB/IEC, the subject’s 
parent(s) or legal guardian(s), or the appropriate regulatory authority, must be kept in confidence 
by the Investigator in accordance with current global data protection standards (eg, Health 
Insurance Portability and Accountability Act and General Data Protection Regulation) and 
applicable local/state privacy requirements. 
Subjects will be referenced by an assigned subject identification number on the eCRFs and other 
data collected by the Sponsor. The Investigator must maintain all documents related to the study 
that identify the subject (eg, the signed informed consent/assent document) in strict confidence, 
except to the extent necessary to allow auditing by the appropriate regulatory authorities, the 
IRB/IEC, the Study Monitor, or the Sponsor or its representatives. In case of any data security 
breach, the Sponsor will investigate and implement necessary actions. 

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15. 
STUDY DOCUMENTATION AND GENERAL INFORMATION 
15.1. 
General Information 
The Investigator should be familiar with and refer, as needed, to the current Investigator’s 
Brochure, along with subsequent Safety Alert Letters, the study-specific Pharmacy Manual, the 
Laboratory Manual, and all other study-specific information that is provided during the study 
initiation visit or throughout the duration of the study. 
15.2. 
Essential Study Documents 
Essential study documents are among the critical documents required before study enrollment is 
to occur. Essential documents, such as the Investigator’s Brochure, study-specific Pharmacy 
Manual, and final protocol, must be kept onsite in a designated study site file.  
The study site files will also contain (including but not limited to) the following: subject study 
drug accountability records, study drug accountability (receipt/dispensing) records, 
Sponsor/Investigator correspondence, IRB/IEC documentation and correspondence, deviations, 
biological sample records, and SAE and Investigational New Drug safety reports/Safety Alert 
Letters/SUSARs. 
15.3. 
Dissemination of Study Results 
The information that is developed during the conduct of this clinical study is strictly confidential. 
This information may be disclosed only as deemed necessary by the Sponsor and collaborators. 
At the conclusion of this clinical study, a clinical study report will be prepared. Data generated 
for this study will be exclusively owned by the Sponsor and collaborators, as detailed in the 
Clinical Trial Agreement. The study will be registered on ClinicalTrials.gov, 
ClinicalTrialsRegister.eu, ClinicalTrials.jp, and to any other registries as required by law. After 
completion of the study, results will be disseminated through the applicable public website(s). 
15.4. 
Publication Policy 
All unpublished information given to the Investigator by the Sponsor and collaborators shall not 
be published or disclosed to a third party without the prior written consent of the Sponsor and 
collaborators.  
Policies regarding the publication of the study results are defined in the Clinical Trial 
Agreement. 
15.5. 
Product Handling and Complaints Reporting 
If there are any issues during the study related to the quality, packaging, labeling, or 
characteristics of the study drug, the Investigator, clinical site pharmacist, or pharmacy designee 
should contact the Sponsor or designated contract research organization as per the Pharmacy 
Manual within 24 hours of awareness. 

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16. 
LIST OF REFERENCES 
AAN. Practice Guideline Update: Corticosteroid Treatment of Duchenne Muscular Dystrophy. 
In, edited by American Academy of Neurology, 3. Minneapolis, MN: American Academy of 
Neurology. 2016. 
Alfano LN, Miller NF, Berry KM, et al. The 100-meter timed test: normative data in healthy 
males and comparative pilot outcome data for use in Duchene muscular dystrophy clinical trials. 
Neuromuscul Disord. 2017 May;27(5):452-7. 
American Academy of Pediatrics Section on Cardiology and Cardiac Surgery. Cardiovascular 
health supervision for individuals affected by Duchenne or Becker muscular dystrophy. 
Pediatrics. 2005;116(6):1569-73. 
Bevans KB, Riley, AW, Moon J, et al. Conceptual and methodological advances in 
child-reported outcomes measurement. Expert Rev Pharmacoecon Outcomes Res. 
2010;10(4):385-96. 
Birnkrant DJ. The American College of Chest Physicians consensus statement on the respiratory 
and related management of patients with Duchenne muscular dystrophy undergoing anesthesia or 
sedation. Pediatrics. 2009;123 Suppl 4:S242-4. 
Birnkrant DJ, Bushby K, Bann CM, et al. Care Considerations Working Group. Diagnosis and 
management of Duchenne muscular dystrophy, Part 3: primary care, emergency management, 
psychosocial care, and transitions of care across the lifespan. Lancet Neurol. 2018;17(5):445-55. 
Brooke MH, Fenichel GM, Griggs RC, et al. Clinical investigation in Duchenne dystrophy: 2. 
Determination of the “power” of therapeutic trials based on the natural history. Muscle Nerve. 
1983;6(2):91-103. 
Bushby K, Connor E. Clinical outcome measures for trials in Duchenne muscular dystrophy: 
report from International Working Group meetings. Clin Investig (Lond). 2011;1(9):1217-35. 
Bushby K, Finkel R, Birnkrant DJ, et al. Diagnosis and management of Duchenne muscular 
dystrophy, Part 2: implementation of multidisciplinary care. Lancet Neurol. 2010;9(2):177-89. 
Ciafaloni E, Fox DJ, Pandya S, et al. Delayed Diagnosis in Duchenne Muscular Dystrophy: Data 
from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet). 
J Pediatrics. 2009;155(3):380-5. 
Connolly AM, Florence JM, Cradock MM, et al. Motor and cognitive assessment of infants and 
young boys with Duchenne Muscular Dystrophy: results from the Muscular Dystrophy 
Association DMD Clinical Research Network. Neuromuscul Disord. 2013;23(7):529-39. 
Department of Health and Human Services Centers for Disease Control and Prevention Division 
of Viral Hepatitis. Interpretation of Hepatitis B Serologic Test Results. Adapted from: A 
Comprehensive Immunization Strategy to Eliminate Transmission of Hepatitis B Virus Infection 
in the United States: Recommendations of the Advisory Committee on Immunization Practices, 
2005. Available at https://www.cdc.gov/hepatitis/hbv/pdfs/serologicchartv8.pdf. Accessed 02 
September 2020. 

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Eagle M, Baudouin SV, Chandler C, et al. Survival in Duchenne muscular dystrophy: 
improvements in life expectancy since 1967 and the impact of home nocturnal ventilation. 
Neuromuscul Disord. 2002;12(10):926-9. 
ELEVIDYS (delandistrogene moxeparvovec-rokl) suspension, for intravenous infusion [package 
insert]. Cambridge, MA. Sarepta Therapeutics, Inc.; 2023.  
EXONDYS 51 (eteplirsen) [package insert]. Cambridge MA. Sarepta Therapeutics, Inc.; 
May 2020. 
Food and Drug Administration. Guidance for Industry Patient-Reported Outcome Measures: Use 
in Medical Product Development to Support Labeling Claims. Available at 
https://www.fda.gov/downloads/drugs/guidances/ucm193282.pdf. Accessed 10 October 2018. 
Gulati S, Saxena A, Kumar V, et al. Duchenne muscular dystrophy: prevalence and patterns of 
cardiac involvement. Indian J Pediatr. 2005 May;72(5):389-93. 
Henricson EK, Abresch RT, Cnaan A, et al. The cooperative international neuromuscular 
research group Duchenne natural history study: glucocorticoid treatment preserves clinically 
meaningful functional milestones and reduces rate of disease progression as measured by manual 
muscle testing and other commonly used clinical trial outcome measures. Muscle Nerve. 
2013;48(1): 55-67. 
Kenward MG, Roger JH. Small sample inference for fixed effects from restricted maximum 
likelihood. Biometrics. 1997;53(3):983-997. 
Khirani S, Ramirez A, Aubertin G, et al. Respiratory muscle decline in Duchenne muscular 
dystrophy. Pediatr Pulmonol. 2014 May;49(5):473-81. 
Mayer OH, Finkel RS, Rummey C, et al. Characterization of pulmonary function in Duchenne 
muscular dystrophy. Pediatr Pulmonol. 2015 May;50(5):487-94. 
Mazzone E, Martinelli D, Berardinelli A, et al. North Star Ambulatory Assessment, 6-minute 
walk test and timed items in ambulant boys with Duchenne muscular dystrophy. Neuromuscul 
Disord. 2010;20(11):712-6. 
McDonald CM. Physical Activity, Health Impairments, and Disability in Neuromuscular 
Disease. Am J Phys Med Rehabil. 2002;81(Suppl):S108–20. 
McDonald CM, Widman LM, Walsh DD, et al. Use of Step Activity Monitoring for Continuous 
Physical Activity Assessment in Boys With Duchenne Muscular Dystrophy. Arch Phys Med 
Rehabil. 2005;86:802-8. 
McDonald CM, Henricson EK, Abresch RT, et al. The 6-minute walk test and other clinical 
endpoints in Duchenne muscular dystrophy: reliability, concurrent validity, and minimal 
clinically important differences from a multicenter study. Muscle Nerve. 2013 Sep;48(3):357-68. 
McMillan HJ, Gregas M, Darras BT, et al. Serum transaminase levels in boys with Duchenne 
and Becker muscular dystrophy. Pediatr. 2011 Jan;127(1):e132-6. 

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Mendell JR, Campbell K, Rodino-Klapac L, Sahenk Z, Shilling C, Lewis S, Bowles D, Gray S, 
Li C, Galloway G, Malik V, Coley B, Clark KR, Li J, Xiao X, Samulski J, McPhee SW, 
Samulski RJ, Walker CM. Dystrophin immunity in Duchenne's muscular dystrophy. N Engl J 
Med. 2010 Oct 7;363(15):1429-37. doi: 10.1056/NEJMoa1000228. PMID: 20925545; PMCID: 
PMC3014106. 
Mendell JR, Rodino-Klapac L, Sahenk Z, et al. Gene therapy for muscular dystrophy: lessons 
learned and path forward. Neurosci Lett. 2012;527:90-9. 
Mercuri E, Muntoni F. Muscular dystrophies. Lancet. 2013;381:845-60. 
Mercuri E, Coratti G, Messina S, et al. Revised North Star Ambulatory Assessment for Young 
Boys with Duchenne Muscular Dystrophy. PLoS One. 2016;11(8):e0160195. 
Passamano L, Taglia A, Palladino A, et al. Improvement of survival in Duchenne muscular 
dystrophy: retrospective analysis of 835 patients. Acta Myol. 2012;31:121-5. 
PROMIS® Pediatric and Parent Proxy Profile Instruments. Available at 
http://www.healthmeasures.net/images/PROMIS/manuals/PROMIS_Pediatric_and_Proxy_Profil
e_Scoring_Manual.pdf. Accessed 10 October 2018. 
Spurney C, Shimizu R, Morgenroth LP, et al, CINRG Investigators. Cooperative International 
Neuromuscular Research Group Duchenne Natural History Study demonstrates insufficient 
diagnosis and treatment of cardiomyopathy in Duchenne muscular dystrophy. Muscle Nerve. 
2014 Aug:50(2):250-6. 
Thomas TO, Morgan TM, Burnette WB, et al. Correlation of heart rate and cardiac dysfunction 
in Duchenne muscular dystrophy. Pediatr Cardiol. 2012 Oct;33(7):1175-9. 
TranslarnaQ™ (ataluren) [Summary of Product Characteristics]. Guildford Business Park, 
Guildford, United Kingdom: PTC Therapeutics Ltd.; 24 Oct 2019. 
VILTEPSO™ (viltolarsen) [package insert]. Paramus, NJ: NS Pharma, Inc.; 2021. 
Zatz M, Rapaport D, Vainzof M, et al. Serum creatine kinase (CK) and pyruvate kinase (PK) 
activities in Duchenne (DMD) as compared with Becker (BMD) muscular dystrophy. J Neurol 
Sci. 1991 Apr;102(2):190-6. 

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APPENDIX 1. GUIDANCE ON CONTRACEPTION USE AND 
PREGNANCY TESTING 
Practical guidance on contraception use and pregnancy testing in clinical trials are provided in 
the following guidance: https://www.hma.eu/fileadmin/dateien/Human_Medicines/01-
About_HMA/Working_Groups/CTFG/2020_09_HMA_CTFG_Contraception_guidance_Versio
n_1.1_updated.pdf  

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CCI

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APPENDIX 3. QUESTIONNAIRES 
PROMIS Parent Proxy Mobility, V2.0  
PROMIS Parent Proxy Upper Extremity, Short Form 8a, V2.0 
 
PROMIS Pediatric Mobility, V2.0 
PROMIS Pediatric Upper Extremity, Short Form 8a, V2.0 
 
 
 
 
 
 
 
 
CCI
CCI
CCI
CCI
CCI
CCI
CCI
CCI
CCI

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APPENDIX 4. PROTOCOL VERSION HISTORY 
 
PPD