Gene Therapy, Open-label, Dose-escalation Study of PF-06838435 (SPK-9001) [Adeno-associated Viral Vector With Human Factor IX Gene] in Subjects With Hemophilia B
Phase: PHASE2
Conditions: Hemophilia B
Sponsor: Pfizer

P F- 0 6 8 3 8 4 3 5
C 0 3 7 1 0 0 5
Fi nal Pr ot oc ol A me n d me nt 7, 1 4 J u ne 2 0 1 9
Pa ge 1
Pr ot oc ol Title: Ge ne t hera p y, O pe n-la bel, D ose-escalati o n St u d y of P F- 0 6 8 3 8 4 3 5 
( S P K- 9 0 0 1) [a de n o-ass ociate d viral vect or wit h h u ma n fact or I X ge ne] i n s u bjects wit h 
he m o p hilia B 
Pr ot oc ol  N u m ber: C 0 3 7 1 0 0 5/ pre vi o usl y S P K- 9 0 0 1- 0 1
A me n d me nt N u m ber: 7
C o m p o u n d N u m ber: P F- 0 6 8 3 8 4 3 5/ pre vi o usl y S P K- 9 0 0 1
Pr o d uct n a me: Fi da nac o ge ne ela par v o vec
St u d y P h ase: P hase 1/ P hase 2a
Le g al Re gistere d A d dress: 2 3 5 East 4 2 n d Street, Ne w Y or k, N Y 1 0 0 1 7
5 7 5 5, U S A
Re g ul at or y A ge nc y I de ntifier N u m ber(s)
Re gistr y
I de ntific ati o n (I D)
I n vesti gati o nal Ne w Dr u g (I N D) 
N u m ber
A p pr o v al D ate: 1 4 J u ne 2 0 1 9
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Protocol Amendment Summary of Changes Table
DOCUMENT HISTORY
Document
Date
Amendment 6.0
1.
Clarification for Exclusion Criteria #1, #3, and #4.
2.
Clarification to the Schedule of Activities footnotes.
3.
Administrative changes throughout. 
4.
Removal of reference to the Immunosuppressive Therapy Dosing Committee as it was 
never formed.
5.
Addition of Table 1: Laboratory assessments and location for analysis.
29-Sep-2017
Amendment 5.1
1.
Modified Dose Level Expansion parameters.
2.
Updated FibroScan score.
3.
Updated Schedule of Activities, removed requirement for FIX incremental recovery at 
Week 52/EOS, added the following: collection of joint health assessments and clarified 
target joint assessments, pain and activity questionnaires, Week 52/EOS urinalysis, liver 
ultrasound.
4.
Revised SPK-9001 empty and full capsid formulation.
5.
Revised Table 1 Regimen for Oral Corticosteroids.
6.
Added provision to collect safety information between Week 52 and roll-over to long-term 
follow-up study.
13-Jan-2017
Amendment 5.0
1.
This version was never submitted to any Regulatory Authority or any Ethics Committee.
22-Dec-2016
Amendment 4.0
1.
Expansion of dose level cohort.
2.
Updated laboratory requirements for screening FIX activity level.
3.
Updated calculation for vector dose calculation to be based on BMI.
4.
Updated Schedule of Activities.
5.
Minor administrative changes throughout.
19-May-2016
Amendment 3.0
1.
Added non-invasive liver diagnostic tests to Exclusion Criteria #3.
2.
Updates to Schedule of Activities.
3.
Update to semen collection timepoints.
4.
Clarification to reference for empty capsid formulation.
5.
Update to Section 8: Study Treatment Management.
03-Mar-2016

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DOCUMENT HISTORY
6.
Update to clinical assessments and laboratory safety assessments.
7.
Update to Appendices A1 and A2.
8.
Minor administrative changes throughout.
Amendment 2.0  
1.
Clarified incremental recovery, laboratory testing frequency, duration of screening period, 
unscheduled visit assessments, hemostasis timepoints, additional safety tests, AE reporting 
responsibilities, duration of safety observation period.
2.
Minor administrative changes throughout.
30-Sep-2015
Amendment 1.2
1.
Added ECG assessment.
2.
Clarified dose escalation.
3.
Removed azathioprine from immunosuppressive therapies.
4.
Clarified laboratory testing.
5.
Added missing information (IND number, some abbreviations.
6.
Minor administrative changes throughout
18-May-2015
Amendment 1.1   
1.
Section 3.2.2 dose level expansion from “≥3% of normal” to “above their baseline”.  
2.
Minor administrative changes throughout.
08-Apr-2015
Original Protocol 1.0
01-Apr-2015
Amendment 7 (14 June 2019)
Overall Rationale for the Amendment:
Section # and Name
Description of Change
Brief Rationale
Section 1.1 Synopsis
Section 1.2 Schema
 
 
 
Section 5.2 Exclusion Criteria
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
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Section # and Name
Description of Change
Brief Rationale
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
Section 1.1 Synopsis
Section 1.3 SoA
Section 3 Objectives, Estimands and 
Endpoints
Section 8.7 Genetics
Section 10.5 Appendix 5 Genetics
 
Banked biospecimens will be collected 
from participants for exploratory research 
relating to the drug response in 
hemophilia B.  
 
 
 
 
•
Section 2.3. Benefit/Risk 
Assessment
•
Section 4.5. End of Study 
Definition
•
Section 5. Study Population
•
Section 5.1. Inclusion Criteria
•
Section 5.4. Screen Failures
•
Section 6. Study Intervention
•
Section 6.2. Preparation/
Handling/ Storage 
/Accountability
•
Section 6.4. Study Intervention 
Compliance
•
Section 7.1. Discontinuation of 
Study Intervention
•
Section 7.2. Participant 
Discontinuation / Withdrawal 
from Study
Template change
The Spark therapeutics protocol 
amendment document was transferred 
into the new Pfizer Common Protocol 
Template (CPT) and mandatory and/or 
suggested CPT language was adopted in 
all the sections listed. 
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Section # and Name
Description of Change
Brief Rationale

Section 7.3. Lost to Follow up

Section 8. Study Assessments and 
Procedures

Section 8.2. Safety Assessments
and Procedures

Section 8.2.5. Clinical Safety 
Laboratory Assessments

Section 8.3. Adverse Events and 
Serious Adverse Events

Section 8.3.1. Time Period and 
Frequency for Collecting AE and 
SAE Information

Section 8.3.1.1. Reporting SAEs 
to Pfizer Safety 

Section 8.3.2. Method of 
Detecting AEs and SAEs

Section 8.3.3. Follow-up of AEs 
and SAEs

Section 8.3.4. Regulatory 
Reporting Requirements for 
SAEs

Section 8.3.5. Exposure During 
Pregnancy or Breastfeeding, and 
Occupational Exposure

Section 8.3.5.1. Exposure During 
Pregnancy

Section 8.3.5.2. Exposure During 
Breastfeeding

Section 8.3.5.3. Occupational 
Exposure 

Section 8.3.7. Medication Errors

Section 8.4. Treatment of 
Overdose

Section 8.7. Genetics

Section 8.8. Biomarkers

Section 9. Statistical 
Considerations

Section 9.1. Estimands and 
Statistical Hypothesis

Section 9.1.1. Estimands

Section 9.3. Populations for 
Analyses

Section 9.4. Statistical Analyses

Section 9.5.1. Data Monitoring 
Committee (DMC)

Section 10. Supporting 
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Section # and Name
Description of Change
Brief Rationale
Considerations

Section 10.1. Appendix 1: 
Regulatory, Ethical, and Study 
Oversight Considerations

Section 10.1.1. Regulatory and 
Ethical Considerations

Section 10.1.2. Financial 
Disclosure

Section 10.1.3. Informed Consent 
Process

Section 10.1.4. Data Protection

Section 10.1.6. Dissemination of 
Clinical Study Data

Section 10.1.7. Data Quality 
Assurance

Section 10.1.8. Source Documents

Section 10.1.9. Study and Site 
Closure

Section 10.10. Publication Policy

Section 10.1.11. Sponsor’s 
Qualified Medical Personnel

Section 10.2. Appendix 2: Clinical 
Laboratory Tests

Section 10.3. Appendix 3: 
Adverse Events: Definitions and 
Procedures for Recording, 
Evaluating, Follow-up, and 
Reporting

Section 10.3.1. Definition of AE

Section 10.3.2. Definition of SAE

Section 10.3.3. Recording and 
Follow-Up of AE and/or SAE

Section 10.3.4. Reporting of SAEs

Section 10.4. Appendix 4: 
Contraceptive Guidance and 
Collection of Pregnancy 
Information

Section 10.5. Appendix 5: 
Genetics

Section 10.6. Appendix 6: Liver 
Safety: Suggested Actions and 
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TABLE OF CONTENTS
LIST OF TABLES...................................................................................................................11
LIST OF FIGURES .................................................................................................................11
1. PROTOCOL SUMMARY...................................................................................................12
1.1. Synopsis ..................................................................................................................12
1.2. Schema ....................................................................................................................18
1.3. Schedule of Activities (SoA)...................................................................................19
2. INTRODUCTION ...............................................................................................................23
2.1. Study Rationale .......................................................................................................23
2.2. Background .............................................................................................................23
2.2.1. Hemophilia B..............................................................................................23
2.2.2. Clinical Manifestations...............................................................................24
2.2.3. Current Therapies for Hemophilia B ..........................................................25
2.3. Benefit/Risk Assessment.........................................................................................27
3. OBJECTIVES, ESTIMANDS AND ENDPOINTS ............................................................27
4. STUDY DESIGN.................................................................................................................29
4.1. Overall Design.........................................................................................................29
4.1.1. Initial Sequence of Enrollment ...................................................................29
4.1.3. Dose Escalation and Expansion..................................................................30
4.1.3.1. Initial Dose Escalation ..............................................................30
4.1.4. FIX Incremental Recovery .........................................................................31
4.1.5. Immunomodulation Optimization (ONLY for Participants Who 
Develop Hepatitis Transaminitis) ....................................................................32
4.1.6. Thrombotic Potential Assessments (ONLY for Participants Who 
Reach Vector-derived FIX:C Activity Levels >150% after the infusion 
of PF-06838435)..............................................................................................34
4.1.7. Duration of Study Participation..................................................................34
4.1.7.1. Screening Period .......................................................................35
4.1.7.2. Dosing Day................................................................................35
4.1.7.3. Post-Infusion .............................................................................36
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4.2. Scientific Rationale for Study Design.....................................................................36
4.3. Justification for Dose ..............................................................................................36
4.3.1. Study Stopping Rules .................................................................................37
4.4. End of Study Definition ..........................................................................................39
4.5. Extension Study (C0371003) ..................................................................................39
5. STUDY POPULATION......................................................................................................39
5.1. Inclusion Criteria.....................................................................................................39
5.2. Exclusion Criteria....................................................................................................41
5.3. Lifestyle Considerations..........................................................................................43
5.4. Screen Failures ........................................................................................................43
6. STUDY INTERVENTION..................................................................................................43
6.1. Study Intervention(s) Administered........................................................................43
6.1.1. Dose Schedule and Administration ............................................................44
6.1.2. FIX Incremental Recovery of FIX Products...............................................44
6.2. Preparation/Handling/Storage/Accountability ........................................................44
6.3. Measures to Minimize Bias: Randomization and Blinding.....................................45
6.3.1. Screening of Participants............................................................................45
6.3.2. Enrollment of Participants..........................................................................46
6.3.3. Randomization............................................................................................46
6.3.4. Blinding Procedures....................................................................................46
6.4. Study Intervention Compliance...............................................................................46
6.5. Concomitant Therapy..............................................................................................46
6.5.1. Allowed Therapy ........................................................................................47
6.5.2. Disallowed Therapy....................................................................................47
6.5.3. Concomitant Procedures.............................................................................47
6.6. Dose Modification...................................................................................................47
6.7. Intervention after the End of the Study...................................................................48
7. DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL...........................................................................48
7.1. Discontinuation of Study Intervention ....................................................................48
7.2. Participant Discontinuation/Withdrawal from Study..............................................48
7.3. Lost to Follow up ....................................................................................................48
8. STUDY ASSESSMENTS AND PROCEDURES...............................................................49

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8.1. Efficacy Assessments..............................................................................................49
8.2. Safety Assessments .................................................................................................50
8.2.1. Physical Examinations................................................................................50
8.2.2. Vital Signs ..................................................................................................50
8.2.3. Electrocardiograms.....................................................................................50
8.2.4. Clinical Safety Assessments.......................................................................50
8.2.5. Clinical Safety Laboratory Assessments ....................................................50
8.3. Adverse Events and Serious Adverse Events..........................................................51
8.3.1. Time Period and Frequency for Collecting AE and SAE Information.......51
8.3.1.1. Reporting SAEs to Pfizer Safety...............................................52
8.3.1.2. Recording Non-serious AEs and SAEs on the CRF .................52
8.3.2. Method of Detecting AEs and SAEs ..........................................................52
8.3.3. Follow-up of AEs and SAEs.......................................................................52
8.3.4. Regulatory Reporting Requirements for SAEs...........................................53
8.3.5. Exposure During Pregnancy or Breastfeeding, and Occupational 
Exposure ..........................................................................................................53
8.3.5.1. Exposure During Pregnancy......................................................53
8.3.5.2. Exposure During Breastfeeding ................................................54
8.3.5.3. Occupational Exposure .............................................................54
8.3.6. Disease-Related Events and/or Disease-Related Outcomes Not 
Qualifying as AEs or SAEs..............................................................................54
8.3.7. Medication Errors .......................................................................................55
8.4. Treatment of Overdose............................................................................................55
8.5. Pharmacokinetics ....................................................................................................56
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9. STATISTICAL CONSIDERATIONS ................................................................................59
9.1. Estimands and Statistical Hypotheses.....................................................................60
9.1.1. Estimands....................................................................................................60
9.1.2. Statistical Hypotheses.................................................................................60
9.2. Sample Size Determination.....................................................................................60
9.3. Populations for Analyses.........................................................................................60
9.4. Statistical Analysis ..................................................................................................61
9.4.1. Efficacy Analyses .......................................................................................61
9.4.2. Safety Analyses ..........................................................................................61
9.4.3. Other Analyses............................................................................................61
9.5. Interim Analyses .....................................................................................................62
9.5.1. Data Monitoring Committee (DMC)..........................................................62
10. SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS..........................................................................................................63
10.1. Appendix 1: Regulatory, Ethical, and Study Oversight Considerations...............63
10.1.1. Regulatory and Ethical Considerations ....................................................63
10.1.2. Financial Disclosure .................................................................................64
10.1.3. Informed Consent Process ........................................................................64
10.1.4. Data Protection .........................................................................................65
10.1.5. Committees Structure ...............................................................................66
10.1.5.1. Independent Data Monitoring Committee...............................66
10.1.5.2. Ethics Committee Notification of Study Completion or 
Termination .......................................................................................66
10.1.6. Dissemination of Clinical Study Data ......................................................66
10.1.7. Data Quality Assurance ............................................................................67
10.1.8. Source Documents....................................................................................68
10.1.9. Study and Site Closure..............................................................................69
10.1.10. Publication Policy...................................................................................69
10.1.11. Sponsor’s Qualified Medical Personnel .................................................70
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10.2. Appendix 2: Clinical Laboratory Tests .................................................................71
10.3. Appendix 3: Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting ......................................................................72
10.3.1. Definition of AE .......................................................................................72
10.3.2. Definition of SAE.....................................................................................74
10.3.3. Recording and Follow-Up of AE and/or SAE..........................................75
10.3.4. Reporting of SAEs....................................................................................78
10.4. Appendix 4: Contraceptive Guidance and Collection of Pregnancy 
Information................................................................................................................80
10.5. Appendix 5: Genetics............................................................................................82
10.6. Appendix 6: Liver Safety: Suggested Actions and Follow-up Assessments ........83
10.7.1. HAEM-A-QOL Questionnaire .................................................................85
10.7.2. EQ-5D-5L Questionnaire..........................................................................92
10.7.3. McGill Pain Questionnaire .......................................................................96
10.7.4. Hemophilia Activities List and Change in Level of Activity.................100
10.8. Appendix 8: Toxicity Scale.................................................................................111
10.9. Appendix 9: Abbreviations .................................................................................113
11. REFERENCES ................................................................................................................116
LIST OF TABLES
Table 1.
Recommended Initial Regimen for Oral Corticosteroids.........................32
Table 2.
Recommended Regimen for Combination Intravenous and Oral 
Corticosteroids..........................................................................................33
Table 3.
Protocol-Required Laboratory Assessments.............................................71
LIST OF FIGURES
Figure 1.
Study Schematic .......................................................................................18
Figure 2.
The Blood Coagulation Cascade11............................................................24
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1. PROTOCOL SUMMARY
1.1. Synopsis
Protocol Title: Gene therapy, Open-label, Dose-escalation Study of PF-06838435 
(SPK-9001) [adeno-associated viral vector with human factor IX gene] in subjects with 
hemophilia B.
Rationale
Adeno-associated virus vector (AAV) vectors have been administered in more than 100 gene 
transfer clinical trials for a wide range of indications, including several studies for 
hemophilia B, and have demonstrated a good safety profile1, 2. Importantly, data from a 
recent clinical study of AAV8 gene transfer to participants with severe hemophilia B, 
sponsored by St. Jude Children’s Research Hospital – University College London (SJ-UCL), 
demonstrated that a single peripheral intravenous (IV) infusion of the self-complementary  
AAV8-LP1-hFIXco resulted in sustained and long-term circulating vector-derived factor IX 
(FIX:C) activity levels of 2-12%, which were sufficient to improve the bleeding phenotype 
and reduce the use of regular prophylactic factor IX (FIX) infusions, in some cases 
completely eliminating them3. The previous Sponsor also conducted a study of an AAV8 
vector for hemophilia B (AAV8-hFIX19, IND 15149) study was recently conducted.  In that 
trial, the vector was well tolerated and all three dosed participants experienced initial 
increases in vector-derived FIX:C activity levels.  For two of the three participants, 
expression was short-lived (~2-4 months), likely due to an immune response to some vector 
component, despite the initiation of an immunosuppressive regimen; for the third participant, 
expression was longer-lived (~18 months), but trended inexorably downward despite the 
immunosuppressive therapy.  The objective of this study is to evaluate the safety, tolerability, 
and kinetics of a single IV infusion of PF-06838435 in hemophilia B participants with ≤2 
International Units (IU)/dL [≤2%] endogenous factor IX levels.
Dose Rationale
PF-06838435 is an AAV vector designed to drive expression of the human coagulation 
factor IX (hFIX) transgene and raise circulating levels of endogenous FIX.  PF-06838435 is 
comprised of a bioengineered AAV capsid, AAV-Spark100, and a codon-optimized 
expression cassette (hFIX39-Padua).  AAV-Spark100 is a novel capsid engineered from a 
naturally occurring AAV serotype, which shows a strong hepatotropic profile in mice and 
non-human primates (NHPs), comparable to AAV8.  The cassette (hFIX39-Padua) encodes 
the hFIX variant that has higher specific activity than the wild-type (WT) FIX due to the 
substitution of an arginine for a leucine at amino acid position 338 (R338L).  
 
 
The non-clinical study in NHPs infused with a similar vector, AAV-Spark100-hFIX19-
Padua, resulted in therapeutic steady-state vector-derived FIX activity levels without safety 
concerns.  PF-06838435 and AAV-Spark100-hFIX19-Padua share the same regulatory 
sequences, differing only in choice of codons for codon optimization.  Furthermore, studies 
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in mice and in NHPs have shown that these two vectors yield comparable FIX expression.  
Thus, the data with AAV-Spark100-hFIX19-Padua in NHPs can be used to predict the 
vector-derived FIX:C activity levels with PF-06838435 in this study.  
An ongoing clinical trial (NCT#01687608) evaluating the safety and efficacy of a self-
complementary AAV8 vector encoding the high specific activity hFIX variant, hFIX-Padua 
(Baxter Healthcare Corporation, BAX-335), is currently being conducted in participants with 
hemophilia B.  Preliminary clinical data of six participants infused at three different dose 
levels (2x1011, 1x1012, and 3x1012 vg/kg) achieving vector-derived FIX:C activity levels 
from <1% to ~60% with no safety concerns were presented at the recent European 
Association for Haemophilia and Allied Disorders (EAHAD) meeting.  Based on Pfizer’s 
knowledge of their results, there have been no thrombotic events observed in the Baxter trial 
to date.  Thus, these data further support the safety of the dose levels being investigated in 
this study.
This study will investigate up to three dose levels (5x1011, 1x1012, and 2x1012 vg/kg).  Safety 
of these dose levels is supported by previous human clinical trials of AAV2 and AAV8 
vectors encoding hFIX, as well as the NHP studies with AAV-Spark100-hFIX19-Padua and 
with PF-06838435, in which dose levels up to 5x1012 vg/kg were infused without evidence of 
adverse effects.  This dose level is ~10-fold higher than the proposed starting clinical dose 
level of 5x1011 vg/kg in this study.  
Study Design
This is a Phase 1/2a, open-label, non-randomized, uncontrolled, dose-escalation and multi-
center study to evaluate the safety, tolerability, and kinetics of a single IV infusion of 
PF-06838435 in hemophilia B participants with ≤2 IU/dL [≤2%] endogenous factor IX [FIX] 
levels.  Up to 30 evaluable participants will be dosed with a single IV infusion of 
PF-06838435 at one of three different dose levels.
Participants will provide informed consent and then undergo screening assessments up to 
6 (±2) weeks prior to PF-06838435 infusion on the Dosing Day (Day 0).  All dosed 
participants will undergo safety observation for a total of 52 (±2) weeks after PF-06838435 
infusion (see the Schedule of Activities).  Participants who complete 52 (±2) weeks (End-of-
Study) will be encouraged to enroll in an extension study evaluating the long-term safety of 
PF-06838435 for up to an additional 5 years. 
Originally, up to 5 evaluable participants may be dosed in each dose level. An initial dose 
level may be expanded up to 10 evaluable participants if at least 3 out of 5 participants 
achieve detectable steady-state vector-derived FIX activity levels above 5%.  If, after the 
above initial dose-level expansion, at least 6 out of 10 participants achieve detectable steady-
state vector-derived FIX activity levels above 5%, then further dose-level expansion of up to 
10 additional evaluable participants would be allowed (a total of up to twenty evaluable 
participants at the starting dose level of 5 x1011 vg/kg).  The administration of PF-06838435 
to the first two participants in the starting dose level will be staggered by at least 2 weeks to 
ensure safety.  Additionally, at least eight weeks of safety data from at least 3 out of 5 
participants in a given dose level will undergo review by an independent data monitoring 

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committee (DMC) prior to dosing the first participant in the next dose level.  Thus, there will 
be at least 8 weeks of staggering administration between dose levels.
 
 
 
Objectives, Estimands and Endpoints
As the primary study objective is the assessment of safety and tolerability of a single IV
infusion of PF-06838435, the estimands are defined here only for the secondary objective of 
the study. This study aims to characterize kinetics of PF-06838435 after a single dose 
administration in the population of participants meeting study’s inclusion/exclusion criteria. 
The vector-derived endogenous (not affected by intercurrent FIX product infusions) FIX:C 
activity levels will be characterized by post-treatment population mean. The assessment will 
be done for each dose of PF-06838435. Since only a single IV infusion of PF-06838435 will 
be administered during the study, there should be no treatment discontinuations. There may 
be missing data, including those from participants lost to follow-up, but it is anticipated to be 
rare. The handling of missing data is discussed in the Statistical Analysis Plan (SAP). 
Objectives
Endpoints
Primary
•
The primary objective is to evaluate the 
safety and tolerability of a single IV
infusion of PF-06838435 in hemophilia 
B participants ≥18 years of age with ≤2 
IU/dL [≤2 %] endogenous factor IX 
[FIX]).
Clinically significant changes from baseline 
in the following:
•
Physical examination
•
Vital signs
•
Laboratory values
•
Incidence of drug-related adverse 
events (AEs) (including inhibitor 
development)
•
FIX incremental recovery (time at 
maximum activity [Tmax] and percent 
recovery for FIX activity)
•
Immune response against AAV capsid 
protein
•
Immune response against hFIX 
transgene
For those individuals who develop hepatic 
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transaminases (alanine aminotransferase
[ALT] and/or aspartate transaminase [AST]) 
elevation of approximately 1.5-fold or 
successively increasing during follow-up 
above baseline (or vector-derived FIX:C 
activity levels decline without evidence of 
FIX inhibitor, accompanied by rising
interferon [IFN] enzyme-linked immunospot 
assays [ELISPOTs] on peripheral blood 
mononuclear cells [PBMCs]) after 
PF-06838435 infusion, treatment with 
corticosteroids will be instituted.  Alternative 
immunosuppressive therapies will be 
considered if the initial corticosteroid 
treatments are not successful.
For any individual who reaches >150% 
vector-derived FIX:C activity levels after the 
infusion of PF-06838435, laboratory 
parameters of thrombotic potential will be 
assessed.
Secondary
•
The secondary objective is to 
characterize the kinetics of PF-06838435.
•
Vector-derived FIX:C activity levels: 
•
Peak
•
Steady-state
•
FIX antigen levels
 
 
 
 
 
 
 
 
 
 
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Overall Design
This is a Phase 1/2a, open-label, non-randomized, dose-escalation and multi-center study to 
evaluate the safety, tolerability, and kinetics of a single IV infusion of PF-06838435 in 
hemophilia B participants with ≤2IU/dL [≤2%] endogenous factor IX [FIX]).  
Approximately 20 participants will be dosed with a single IV infusion of PF-06838435 at one 
of three different dose levels.
Disclosure Statement
This is a single group treatment study with 1 Arm that has no masking.
Number of Participants
Approximately 20 participants will be dosed with a single IV infusion of PF-06838435. 
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Intervention Groups and Duration
The total duration of the study is approximately 58 weeks, including 6 (±2) weeks of 
Screening.  The study will include the following phases:

Screening period [up to 6 (±2) weeks]; 

Dosing day – Day 0 [up to 24 hours];

Safety observation period [52 (±2) weeks].  

Telephone follow-up calls may be conducted by the study staff after the completion 
of the Week 52 (or End-of-Study) visit until participants have been enrolled into the 
extension study (for the monitoring of adverse events). Participants who complete 52 
(±2) weeks of safety observation (End-of-Study) will be encouraged to enroll in an 
extension study evaluating the safety, durability, and efficacy of PF-06838435 for an 
additional 5 years, approximately (a total of 6 years, approximately, when including 1 
year from this study).
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1.2. Schema
Figure 1.
Study Schematic
a.
96 hours (4 days) washout for plasma derived (pd)- or rFIX [or up to 168 hours (7 days) washout for 
extended half-life rFIX]
b.
FIX incremental recovery for FIX products up to 24 (±1) hours after the infusion of the FIX products.
c.
First two participants at the starting dose level will be infused at least 2 weeks apart.
d.
The first two participants will be infused at least 8 weeks apart.  As dose escalation did not occur during the 
course of this study prior to this amendment (v.7) participants entering the study (low antibody positive) 
will begin at this dose level. These participants will be dosed at 8-week intervals. If dose escalation occurs, 
the 8-week interval will remain.  
  Dose escalation criteria for starting dose 5x1011 vg/kg group or 1x1012 vg/kg group are described in
Section 4.1.3.2

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1.3. Schedule of Activities (SoA)
Tests and Assessments
Week
-6 to -11
Day 02
Week 1 - 18
(±2 days)
Week 22 - 52
(±2 weeks)
Unscheduled 
Visits3
Screening
Pre-
Vector 
Dosing
Vector 
Dosing
1
2
3
4
5
6
7
8
10
12
14
16
18 22 26
32 42
52 or
End-of-
Study
Informed Consent 4
X
Demographics, Medical, Surgical and 
Hemophilia History (including genotype 
and HLA) 5
X
Physical Exam, Height, Weight 6, and 
Vital Signs 7, 8
X
X 6, 10
X 6, 8
X
X
X
X
X
X
X
X
X
X
X 6
Liver ultrasound
X 9
X
Target Joint Assessment 10
X 9
X
Laboratory
HBV, HCV, CD4, and HIV Serology
Vaccination History 11
X
α-fetoprotein 
X
X
Standard Safety Panels 12
X
X
X
X
X
X
X
X
X
X
X
X
X
Lipid Panel and Urinalysis (dipstick)
X
X
LFT and Immunology Tests 13, 14
X
X
X14 X14 X14 X14 X14 X14 X14X14 X
X
X
X
X
X
X
X
X
X
Coagulation (aPTT, INR, and TAT) 15
X
X
FIX Activity and Antigen 14
X
X
X14 X14 X14 X14 X14 X14 X14X14 X
X
X
X
X
X
X
X
X
X
Bethesda Assay for FIX Inhibitor 
X
X
X
X
X
X
X
X
X
X
AAV Neutralizing Antibody
X
X
X
X
X
X
X
X

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Tests and Assessments
Week
-6 to -11
Day 02
Week 1 - 18
(±2 days)
Week 22 - 52
(±2 weeks)
Unscheduled 
Visits3
Genomic Banked Biospecimens Prep-
D1
X29
Global Hemostasis Markers 19
X
X
FIX Product Infusion 17
X
FIX Incremental Recovery 18
X
PF-06838435 Infusion 16,20
X
Review Infusion Log
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
Participant’s QoL Assessment and Changes 
in Level of Activity Questionnaires 21
X 9
X
X
X
X
Health-economic Assessment 
X
X
X
X
X
 
 
 
Immunomodulation 23
     LFT, Coagulation, Immunology23
<<<<<     As indicated to monitor immunomodulation optimization (see Section 4.1.5)     >>>>>
     Lipid Panel23, Urinalysis23
<<<<<     As indicated to monitor immunomodulation optimization (see Section 4.1.5)     >>>>>
     HCV-RNA Viral Load 23
<<<<<     As indicated to monitor immunomodulation optimization (see Section 4.1.5)     >>>>>
     CD4 / HIV Viral Load 23
<<<<<     As indicated to monitor immunomodulation optimization (see Section 4.1.5)     >>>>>
Thrombotic Potential Assessment
    (aPTT, INR, 
 and TAT) 24
<<<<<     As indicated in Section 4.1.6     >>>>>
Additional Safety Tests 25
X
Spare Plasma (2mL) 26
X
Serious and non-serious adverse event 
monitoring 27
X
<<<<<     ongoing     >>>>>
Concomitant Therapy 28
X
<<<<<     ongoing     >>>>>
AAV = adeno-associated virus vector; LFT = liver function test; aPTT = activated partial thromboplastin time; FIX = coagulation factor IX; HBV = hepatitis B; HCV = hepatitis C;
HIV = human immunodeficiency virus; HLA = human leukocyte antigen; INR = international normalized ratio; RNA = ribonucleic acid; TAT = thrombin-antithrombin; TGA = 
thrombin generation assay
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Notes for Schedule of Activities:
See Appendix 2 for list and description of samples collected including designation for where analysis will occur, local and/or central laboratory for each analyte.
1.
The Screening period may be extended up to two weeks for participants who experience a bleed and require infusion(s) with FIX protein products within 96 hours prior to PF-
06838435 infusion (Day 0). The reason for extending the screening period must be documented. If the screening period is prolonged greater than 8 weeks, then the participant will need 
to repeat all screening tests and a new Subject ID will be assigned.  
2.
At least 96 hours (4 days) washout for regular factor IX products (or up to 168 hours [7 days] washout period for extended half-life factor IX products) on Day 0 prior to infusion 
is required. The investigational product should NOT be thawed prior to confirmation from the site staff regarding the participant’s washout criteria.
3.
Unscheduled visits to monitor safety and changes in FIX activity may be necessary during the study. An unscheduled visit may include, but is not limited to, monitoring of hepatic 
transaminases, FIX transgene expression (FIX activity), FIX antigen (Ag), CPT™ for peripheral blood mononuclear cells (PBMCs) by enzyme-linked immunospot (ELISPOT). A 
sample for PAXgene RNA may be collected and stored for analysis at the end of study. Any spare plasma from already collected blood samples may also be stored for repeat or 
additional testing as needed.
4.
Informed consent must be obtained from participants prior to any study-related procedures being performed.
5.
Demographics include gender, race, date of birth (month and year only), and ethnicity.
Hemophilia history includes (but is not limited to) the date of diagnosis, severity of disease, genotype, HLA, number of exposures to FIX products, type of FIX products received, 
current dose and infusion regimen of FIX, last dose of FIX received prior to Screening and the first dose of PF-06838435, number of bleeding episodes and factor infusions in the 52 
weeks prior to screening, inhibitor history, and allergy/anaphylaxis history.
If genotype and HLA are not known, sample(s) will be drawn for analysis at Screening.  Genotype is not a criterion for inclusion or exclusion.  However, a documented genotype 
known to produce a clinically severe phenotype of hemophilia B is required if the participant is otherwise unable to demonstrate severity.
6.
Height (cm) is measured at Screening or Day 0 and at End-of-Study visits (Week 52).
Physical Exam is comprehensive (not targeted) and is performed at all clinic visits.
On Day 0 pre-vector infusion, perform physical exam, obtain height (if not available from Screening) and weight; no need to repeat these evaluations post-vector infusion.
Weight (kg) obtained during Screening (the weight obtained from the most recent visit prior to Day 0) will be used to calculate the dose of FIX protein product for FIX incremental 
recovery and for the dose of PF-06838435.
7.
Vital signs include blood pressure (BP), pulse (P), respiratory rate (RR), and oral temperature (°C/°F), and should be taken after the participant has been resting supine or upright 
for 5 minutes.
8.
At Day 0 (for FIX product infusion), obtain vital sign measurements prior to infusion with FIX protein product.
At Day 0 (for PF-06838435 infusion), obtain vital sign measurements at pre-infusion, 30 ± 2 minutes from the start-of-infusion, end-of-infusion ±2 minutes, 3 hours ± 10 minutes, 6 
hours ± 10 minutes and 24 (±1) hours from the start-of-infusion of PF-06838435.
9.
The assessment needs to be completed between Screening visit and pre-vector infusion.
10. Definition of target joint is described in Section 8.10.3.  Assessments include identification of target joints and performance of hemophilia joint health score (HJHS).
11. Screening serology will be performed as follows:  
For all participants: hepatitis B surface antigen (HBsAg), total hepatitis B core antibody (anti-HBc), HBV-DNA; 
For all participants: HCV-RNA load assay; 
For HIV-positive participants: CD4+ count and HIV-1 viral load.  
Screening Fibroscan (locally), FibroTest/Fibrosure (Central Laboratory [CL]), or AST-to-Platelet Ratio Index (Local Laboratory [LL] & CL) is required to rule out underlying liver 
disease in all participants without a known pre-existing diagnosis of portal hypertension, splenomegaly, or hepatic encephalopathy.
12. Laboratory Safety Panels:
Hematology – white blood cell (WBC) count and differential, red blood cell (RBC) count, hemoglobin, hematocrit, 
 and platelet count; ABO blood group at screening only (if not 
known at Screening)
Clinical Chemistry – sodium (Na), potassium (K), chloride (Cl), phosphate, carbon dioxide (CO2), glucose, blood urea nitrogen [BUN], and serum creatinine
13. LFTs – albumin, total bilirubin, direct bilirubin, indirect bilirubin, alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein, 
gamma-glutamyl transferase (GGT), and lactate dehydrogenase (LDH); 
Immunology - CPT™ for PBMC by ELISPOT and PAXgene for RNA. PAXgene samples will be stored for analysis at the end of study.
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14. Hepatic transaminases and FIX transgene expression will be monitored twice-weekly or thrice-weekly to detect early changes. Between Weeks 1 and 12 post-vector infusion, 
monitoring will include LFTs, FIX:C, FIX Ag, CPT™ for PBMC by ELISPOT and PAXgene for RNA. Spare plasma, from already collected blood samples will be stored for repeat or 
additional tests.  Some participants may need more frequent monitoring using unscheduled visits.
15. Activated partial thromboplastin time (aPTT) measured in seconds; TAT will be taken just prior to the infusion of FIX product.
16. Participants should be advised to temporarily suspend prophylaxis regimen after vector infusion until being advised by the Investigator to resume.
17. At Day 0, participants should arrive at the clinic with at least 96 hours (4 days) washout of pd-FIX/rFIX or up to 168 hours (7 days) washout of extended half-life FIX product.  
Participants will receive a single IV infusion of 100 IU/kg of FIX protein product over 10 (±2) minutes.
18. Blood samples will be collected at pre-infusion, 10 (±2) minutes, 1 hour ± 10 minutes, 3 hours ± 10 minutes, 6 hours ± 10 minutes, and 24 (±1) hours from the start-of-infusion of 
FIX protein product.
19. Thromboelastography (TEG) and/or rotational thromboelastogram (ROTEM) – Only selected participants at selected sites capable of performing these tests locally.
  
Blood samples will be collected at pre-infusion and 10 (±2) minutes from the start-of-infusion of FIX protein product on Day 0 and End-of-Study Visits.
20. After the completion of FIX protein product infusion, participants will receive PF-06838435 infused via infusion pump over a period of approximately 60 minutes.
21. Haem-A-QoL, EQ-5D-5L, McGill pain questionnaire, and Hemophilia Activities List (including Changes in Level of Activity) questionnaires will be completed by the 
participants.
 
 
 
23. Immunomodulation See Appendix 2: possible tests below:
LFT – albumin, total bilirubin, direct bilirubin, indirect bilirubin, ALP, AST, ALT, total protein, GGT, and LDH;
Coagulation –aPTT, FIX:C, FIX Ag
Immunology - CPT™ for PBMC by ELISPOT and PAXgene for RNA.
Lipid Panel – total cholesterol, HDL (high density lipoprotein), LDL (low density lipoprotein), VLDL (very-low-density lipoprotein), triglycerides,
Serology -  HCV-RNA / HCV viral load (if indicated); CD4 / HIV viral load (if indicated);
Urinalysis using dipstick to monitor protein, ketone, pH, specific gravity, and blood.
24. See Appendix 2: possible tests include aPTT, INR, 
 and TAT
25. Additional tests for safety (deemed clinically necessary for evaluation of clinical symptoms or abnormal laboratory findings).  For example, ECG for 
participants >50 years of age.
26. At each blood collection spare plasma (2 mL) from already collected samples will be stored for repeat or additional tests, if needed.
27. Adverse events will be recorded from the time of the start of PF-06838435 infusion through the End-of-Study visit.  Any SAE experienced by the participant 
from the day of signing the ICF through End-of-Study is to be recorded, regardless of the severity of the event or relationship to study treatment.
28. Concomitant medications and procedures with a start date up to 30 days prior to Screening through the End-of-Study visit will be recorded.
29. If not collected on the designated collection day, collect at the next available time point when biospecimens are being collected in conjunction with a participant 
visit.
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2. INTRODUCTION
PF-06838435 is an adeno-associated viral (AAV) vector designed to drive expression of the 
human factor IX-Padua (hFIX-Padua) transgene and raise the circulating levels of 
endogenous factor IX (FIX:C).  The Guidance for Industry: Considerations for the Design of 
Early-Phase Clinical Trials of Cellular and Gene Therapy Products4 and findings from 
previous clinical studies with AAV2 and AAV8 vectors were considered in the development 
of this protocol.
2.1. Study Rationale
Data from a recent clinical study of AAV8 gene transfer to participants with severe 
hemophilia B, sponsored by SJ-UCL (IND 14031), demonstrated that a single peripheral IV
infusion of the scAAV8-LP1-hFIXco resulted in 2-12% sustained and long-term vector-
derived FIX:C activity levels which were sufficient to improve the bleeding phenotype and 
reduce the use of regular prophylactic FIX infusions, in some cases completely eliminating 
the need for these infusions3, 5.  A recently conducted clinical study using AAV8-hFIX19 in 
three participants with hemophilia B (IND 15149) at 1x1012 and 2x1012 vg/kg, resulted in 
vector-derived FIX:C activity levels of up to 16%.  Furthermore, preliminary data of a single 
peripheral IV infusion of self-complementary BAX-335 (scAAV8.hFIX-Padua) at doses of 2 
x1011 vg/kg, 1x1012 vg/kg and 3x1012 vg/kg from the ongoing Baxter study (NCT#01687608) 
also resulted in detectable vector-derived FIX:C activity levels of <1 to ~60% in six 
participants6.  These recent clinical studies demonstrate that AAV vectors are well tolerated.
After a single administration of AAV-Spark100-hFIX19-Padua into NHPs, steady-state hFIX 
activity levels up to 31%, 68%, and 296% of normal were achieved at 1x1012, 2x1012, and 
5x1012 vg/kg dose levels respectively, without safety concerns.  PF-06838435 and AAV-
Spark100-hFIX19-Padua share the same regulatory sequences and encode identical amino 
acid sequences.  Furthermore, studies in mice and in NHPs have shown that these two 
vectors yield comparable FIX expression.  The objective for this study is to evaluate the 
safety, tolerability, and kinetics of a single administration of PF-06838435 in participants 
with hemophilia B.
2.2. Background
2.2.1. Hemophilia B
Hemophilia B, or Christmas disease, is a deficiency of blood coagulation factor IX (FIX) and 
is recessively inherited due to an X-chromosome mutation carried by females and expressed 
mainly by males, affecting approximately 80,000 people worldwide7, 8.  A deficiency of FIX 
results in bleeding into joints, soft tissue, and muscle.  Fatal intracranial bleeding is one of 
the most serious events that can affect individuals with hemophilia B from neonates to the 
elderly.  Bleeding may be associated with trauma or can occur in the absence of trauma 
(spontaneous bleeding).  Depending on the severity of the bleeding event, it can be life-
threatening if not treated appropriately.  Factor IX, a serine protease, and factor VIII, a 
cofactor for FIX, work in concert to activate factor X, a central step in the coagulation 
cascade.  The coagulation cascade has two pathways, the Contact Activation Pathway 
(Intrinsic Pathway) and the Tissue Factor Pathway (Extrinsic Pathway).  The plasma factors 
are activated in the form of a cascade or “waterfall” 9, 10one after the other until the soluble 

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plasma protein, fibrinogen, is transformed into a fibrinous clot.  The blood coagulation 
cascade is illustrated in Figure 2.
Figure 2.
The Blood Coagulation Cascade11
Although platelets are critical to the formation of the hemostatic plug, an effective clot 
cannot be formed without adequate levels of procoagulant factors.  The level of coagulation 
factors in the plasma of normal individuals range from 50 to 150% (or 50 to 150 IU/dL) of 
the level in normal pooled plasma.  Therefore, clinical features and factor coagulant activity 
define the severity of the disease.  
2.2.2. Clinical Manifestations
About 70% of newborn babies with hemophilia have a positive family history.  When the 
diagnosis is not suspected based on a positive family history, affected children present with 
bleeding from the umbilical stump, prolonged bleeding after circumcision, bleeding 
following intramuscular immunization, excessive bruising, or rarely with intracranial 
hemorrhage.  Individuals with hemophilia B (circulating factor IX level ≤2% or less than 
≤2 IU/dL) frequently experience bleeding and recurrent spontaneous bleeding events into 
muscle, soft tissue, and joints (hemarthroses) starting from infancy and throughout adulthood.  
Examples of bleeding events include intracranial hemorrhage, deep muscle and joint 
hemorrhage, hematomas, retroperitoneal hemorrhage, bleeding following tooth extraction, 
post-surgical bleeding, easy bruising, and mucosal bleeding.  Musculoskeletal hemorrhages 
can lead to recurrent hemarthroses and the development of target joints (generally accepted 

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criterion is a minimum of three bleeds into a single joint within a consecutive three-month 
period12). The inevitable result of such bleeding events is progressive joint damage, leading 
to disabling arthritis with major effects on physical and psychosocial quality-of-life (QoL) 
and socio-economic parameters for hemophilia patients.  Intracranial hemorrhage is a leading 
cause of death among individuals with hemophilia, with a mortality rate of up to 50% in 
adults as well as in children.  Intracranial hemorrhage can occur after trauma, but as many as 
50% of cases occur spontaneously13.  
Development of alloantibodies to FIX (ie, inhibitors) is the main complication of any factor 
replacement therapy14-16.  Inhibitory antibodies (usually immunoglobulin G subclass 4
[IgG4]) antibodies that neutralize the procoagulant activity of FVIII or FIX) develop in 
approximately 3-5% of patients with hemophilia B following exposure to factor replacement 
therapy.  This is a lower frequency than is seen in severe hemophilia A.  However, 
hemophilia B inhibitors may present with anaphylactic responses to infusion of factor IX 
products.  In the presence of inhibitory antibodies, replacement of the missing clotting factor 
by infusion of FIX becomes less effective.  Once replacement therapy is ineffective, acute 
management of bleeding requires agents that bypass FIX activity.  Long-term management of 
inhibitors in hemophilia A typically consists of eradicating the inhibitor through immune 
tolerance.  However, this method is more problematic and less effective in hemophilia B, 
especially in association with anaphylaxis.  Therefore, development of inhibitors 
significantly adds to patients’ disease burden.  
2.2.3. Current Therapies for Hemophilia B
There is no available cure for hemophilia B.  Factor replacement therapy purified from 
human plasma first became available more than four decades ago.  Although these factor IX 
products dramatically improved life expectancy and QoL in the USA and Western Europe, 
they also resulted in exposure of individuals with hemophilia to blood borne viruses – most 
significantly hepatitis B (HBV), hepatitis C (HCV), and the human immunodeficiency virus 
(HIV).  HIV sero-conversion studies documented that most individuals with hemophilia were 
infected between 1978 and 198417, 18. In the U.S.A., most patients with severe hemophilia 
who were born before 1987 are HIV positive, and many have already died from 
complications related to the acquired immune deficiency syndrome (AIDS).  HCV disease 
can cause chronic and progressive hepatitis, with eventual development of cirrhosis, and 
affects the majority of persons with hemophilia B born before 1987.  Late complications of 
HCV are an increasing cause of death in adults who have been infected for decades19,7.  In 
the 1990’s, concerns of viral contamination20 precipitated the development of high-purity 
virus-inactivated plasma-derived products and genetically engineered recombinant factors 
with no animal- or human-plasma-derived proteins to minimize the risk of disease 
transmission21, 22.  However, these products have not circumvented all of the problems of 
protein-based therapies23, 24.
Current treatment of the disease is based on venipuncture and IV administration of either 
plasma-derived or recombinant FIX protein replacement home therapy to raise the circulating 
FIX (FIX:C) activity level to the lowest effective dose to achieve either resolution of 
bleeding (on-demand treatment) or prevention of bleeding8, 25, 26 (prophylaxis treatment). 
Venous access via peripheral veins remains the preferred option for the administration of FIX 

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products27 because it allows a large amount of product to be administered frequently as a 
short infusion using small needles (23-25 gauge).  The frequency of administration of FIX 
products varies among individuals and is tailored to the individual’s clinical status, taking 
into consideration the type of bleed, frequency of bleeding, and goal of treatment for the 
participant.  Both U.S. National Hemophilia Foundation and the World Federation of 
Hemophilia8 established recommendations of plasma factor levels and duration of 
administration for different types of bleeds based on observations over the years.  
Improvements in FIX replacement therapy have vastly increased the QoL and life expectancy 
of individuals with hemophilia B; a recently licensed modified FIX agent with extended half-
life28 provided more convenient dosing options29.  Prophylactic therapy for hemophilia has 
gradually increased among the adult population in the U.S.A. but is still not universally 
practiced for several reasons. The expense is prohibitive (an average adult individual with 
severe hemophilia who elects on-demand treatment to resolve bleeding events spends 
$100,000 on factor replacement therapy each year; prophylaxis treatment may triple the 
yearly cost). Furthermore, children lacking suitable peripheral veins may require central 
venous access devices (CVADs) for factor infusion, which may result in catheter-related 
infections and local thrombotic complications30 that greatly affect the durability of the device 
for the patient31.  Reported rates of catheter-related infection due to the residual blood left at 
the infusion site in hemophilia vary widely; a meta-analysis calculated a pooled incidence of 
infection of 0.66 per 1000 CVAD days31 (CI: 0.44-0.97 per 1000 CVAD days).  Extended 
half-life FIX protein products that require less frequent infusions may potentially decrease 
problems related to venous access32, 33.
Gene therapy has been the goal for curative treatment of hemophilia since the initial cloning 
of the genes more than 30 years ago.  As a proposed alternative approach, gene therapy may 
potentially reduce short-term disability and long-term hemophilic arthropathy, reduce 
incidence of central nervous system (CNS) bleeding, eliminate the need for indwelling IV
catheters or frequent factor infusion, and improve participants’ overall QoL and functional 
independence34.  Indeed, this prediction has been borne out in the recent SJ-UCL clinical trial, 
in which all 10 participants who received gene transfer have reduced their use of prophylactic 
factor products.  Additionally, at least 5 of these participants have reduced factor 
consumption by greater than 90% while remaining free of spontaneous bleeding episodes3, 5.
Several features make hemophilia B a good model for gene therapy.  The first advantage of 
hemophilia B as a model for gene therapy is that precise regulation of transgene expression is 
not required.  Therapeutic range is remarkably wide, from >1% to 150% of normal.  It is 
clear, based on data from administration of FIX products into patients with hemophilia B, 
that levels above ≤150% are not associated with ill-effects since the protein circulates as a 
zymogen (inactive precursor).  Second, as stated, >1% circulating FIX activity levels may 
provide protection against chronic arthropathy and CNS bleeding.  Patients with levels of 
>5% have mild severity and only rarely experience spontaneous bleeding episodes (although 
they exhibit abnormal bleeding in response to hemostatic challenges such as surgery or 
trauma).  A third advantage of hemophilia B is the availability of large and small animal 
models of the human disease.  Clearly, animal models are major assets in efforts to establish 
an experimental basis for gene therapy. In the case of hemophilia, there are well 
characterized, naturally occurring canine models of the disease and genetically engineered 
hemophilic mice 35, 36,37,38, 39. Finally, it should be noted that determination of therapeutic 

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efficacy is straightforward and unequivocal in the case of hemophilia B since plasma levels 
of FIX are easy to measure and correlate well with clinical disease severity.
2.3. Benefit/Risk Assessment
More detailed information about the known and expected benefits and risks and reasonably 
expected adverse events of PF-06838435 (fidanacogene elaparvovec) may be found in the 
Investigator’s Brochure, which is the single reference safety document (SRSD) for this study. 
3. OBJECTIVES, ESTIMANDS AND ENDPOINTS
Objectives
Endpoints
Primary

The primary objective is to evaluate the 
safety and tolerability of a single IV
infusion of PF-06838435 in hemophilia 
B participants ≥18 years of age with ≤2 
IU/dL [≤2 %] endogenous factor IX 
[FIX]).
Clinically significant changes from baseline 
in the following:

Physical examination

Vital signs

Laboratory values

Incidence of drug-related adverse 
events (including inhibitor 
development)

FIX incremental recovery (time at 
maximum activity [Tmax] and percent 
recovery for FIX activity)

Immune response against AAV capsid 
protein

Immune response against hFIX 
transgene
For those individuals who develop hepatic 
transaminases (ALT and/or AST) elevation 
of approximately 1.5-fold or successively 
increasing during follow-up above baseline 
(or vector-derived FIX:C activity levels 
decline without evidence of FIX inhibitor, 
accompanied by rising IFN ELISPOTs on 
PBMCs) after PF-06838435 infusion, 
treatment with corticosteroids will be 
instituted.  Alternative immunosuppressive 

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therapies will be considered if the initial 
corticosteroid treatments are not successful.
For any individual who reaches >150% 
vector-derived FIX:C activity levels after the 
infusion of PF-06838435, laboratory 
parameters of thrombotic potential will be 
assessed.
Secondary
•
The secondary objective is to 
characterize the kinetics of PF-06838435.
•
Vector-derived FIX:C activity levels: 
•
Peak
•
Steady-state
•
FIX antigen levels
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
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As the primary study objective is the assessment of safety and tolerability of a single IV
infusion of PF-06838435, the estimands are defined here only for the secondary objective of 
the study. This study aims to characterize kinetics of PF-06838435 after a single dose 
administration in the population of participants meeting study’s inclusion/exclusion criteria. 
The vector-derived endogenous (not affected by intercurrent FIX product infusions) FIX:C 
activity levels will be characterized by post-treatment population mean. The assessment will 
be done for each dose of PF-06838435. Since only a single IV infusion of PF-06838435 will 
be administered during the study, there should be no treatment discontinuations. There may 
be missing data, including those from participants lost to follow-up, but it is anticipated to be 
rare. The handling of missing data is discussed in the Statistical Analysis Plan (SAP). 
4. STUDY DESIGN
4.1. Overall Design
This is a Phase 1/2a, open-label, non-randomized, dose-escalation and multi-center study to 
evaluate the safety, tolerability, and kinetics of a single IV infusion of PF-06838435 in 
hemophilia B participants with ≤2IU/dL [≤2%] endogenous factor IX [FIX]).  Approximately 
20 evaluable participants will be dosed with a single IV infusion of PF-06838435 at one of 
three different dose levels, see Schema in Section 1.2.     
4.1.1. Initial Sequence of Enrollment
The following two staggering strategies are employed in this study based on the 
recommendation from The Guidance for Industry: Considerations for the Design of Early-
Phase Clinical Trials of Cellular and Gene Therapy Products4:
1. The first two participants at the starting dose level (5x1011 vg/kg) will be infused with 
PF-06838435 at least 2 weeks apart; and
2. There will be at least 8 weeks of staggering between each dose level.  At least 8 weeks of 
safety data from at least 3 out of 5 participants in a given dose level will undergo review 
by an independent DMC prior to dosing the first subject in the next dose level.
A schematic of the study design is presented as Figure 1 Section 1.2
C
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4.1.3. Dose Escalation and Expansion
4.1.3.1. Initial Dose Escalation
Dose escalation and dose level expansion strategies are employed in the study based on 
vector-derived FIX activity levels as well as any immune responses against AAV capsid.  
There will be no dose escalation if at least 3 participants in any dose level achieve steady-
state vector-derived FIX activity levels of ≥40%.  Steady-state levels are based on 2 separate 
vector-derived FIX:C activity level measurements (at least two weeks apart) starting from 
Week 8-12 with adequate washout (ie, 96 hours for factor IX plasma-derived [pd]- or r-FIX 
and up to 168 hours for extended half-life recombinant factor IX (rFIX) from FIX product.
Dose escalation will occur under the following scenarios:
1. If neither of the first two participants in a given dose level achieve detectable steady-state 
vector-derived FIX activity levels above their baseline, then escalation to the next dose 
level will occur, provided there are no safety concerns; or
2. If less than 3 evaluable dosed participants in a given dose level achieve steady-state 
vector-derived FIX activity levels between 3% to 40% of normal, then escalation to the 
next dose level will occur, provided there are no safety concerns.
At least 8 weeks of safety data from at least 3 out of 5 participants in a given dose level will 
undergo review by the independent DMC prior to infusing the first participant in the next 
dose level (See Section 4.1.1 for staggering strategy).  The decision to dose escalate will 
require the agreement of Pfizer and DMC.
Dose level expansion will occur for the following scenarios:
1. If at least one of the first two participants at the low or middle dose level achieve steady-
state vector-derived FIX activity level above their baseline, then up to an initial 5 
evaluable participants will be dosed at the respective dose.
2. If one or both of the first two participants in any dose level achieve circulating vector-
derived FIX activity levels above their baseline (without using any FIX product) but with 
a decline to their baseline levels due to an immune response to vector capsid that is NOT 
well-managed by corticosteroids, then dose escalation will not occur, and instead up to a 
total of 5 evaluable participants will be dosed at the respective dose.
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3. If at least 3 out of 5 participants in the given dose level [scenario “1” above] achieve 
steady-state vector-derived FIX activity levels above 5%, then the initial dose level may 
be expanded up to 10 evaluable participants.
4. If at least 6 out of 10 participants in the given dose level [scenario “3” above] achieve 
steady-state vector-derived FIX activity levels above 5% after the initial dose-level 
expansion, then the initial dose level may be further expanded by up to 10 additional 
participants (a total of 20 evaluable participants would be allowed).
 
 
 
 
 
 
 
 
4.1.4. FIX Incremental Recovery
FIX incremental recovery will be measured up to 24 (±1) hours post-infusion of FIX protein 
products to assess time at maximum activity and percent recovery for exogenous FIX activity.  
The exogenous FIX activity levels will be determined by one-stage clotting assay.  
Participants are required to have at least 96 hours of washout for pd- or r-FIX or up to 
approximately 168 hours of washout for extended half-life rFIX prior to FIX incremental 
recovery test on Dosing Day (Day 0).
FIX incremental recovery assessments will be conducted by collecting blood samples at 
various time-points up to 24 (±1) hours from the start of FIX protein product infusion. Blood 
samples on Day 0 will be collected pre-infusion, 10 (±2) minutes, 1 hour ± 10 minutes, 3 
hours ± 10 minutes, 6 hours ± 10 minutes, and 24 (±1) hours from the start-of-infusion of 
FIX protein product. 
Samples for thrombin generation assessments will also be collected on Day 0 at pre-infusion 
and 10 (±2) minutes from the start-of-infusion of FIX protein infusion and evaluated by an 
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 performed at the central laboratory.  For participants at selected sites 
depending on the testing capabilities, additional samples for global hemostasis may also be 
collected at pre-infusion and 10 (±2) minutes from the start-of-infusion of FIX protein 
infusion and evaluated by the whole blood TEG and/or rotational thromboelastogram 
(ROTEM) locally.
4.1.5. Immunomodulation Optimization (ONLY for Participants Who Develop 
Hepatitis Transaminitis)
Based on observation and experience from earlier clinical studies of liver-directed AAV gene 
transfer, including the SJ-UCL trial3, 5, earlier clinical studies sponsored by Spark 
Therapeutics’, who was also the initial Sponsor of this study, and the Baxter trial 
(NCT#01687608), participants may develop an apparent immune response to the vector 
capsid participants, as evidenced by a transient rise in transaminases (AST and/or ALT) and 
an increase in AAV capsid-specific T cells in the peripheral blood. Immunomodulation will 
be instituted for these participants in an effort to limit the immunologic response in the liver 
and maintain endogenous FIX expression.
A tapering course of oral corticosteroids will be the first consideration for suppression of 
apparent immune hepatitis.  The rationale for this approach is that corticosteroids are 
effective in severe autoimmune hepatitis, a disease in which hepatocytes are attacked by 
epitope-specific cytotoxic T lymphocyte (CTL).  The mechanism for this immune reactivity 
is not clear, but viruses may be causal.
Based on guidelines published by the American Association for the Study of Liver Diseases
(AASLD) 41, 42 and in the absence of alternative etiology, and from the study data of the SJ-
UCL group, treatment for vector-induced hepatitis would be instituted if:
1. In the absence of alternative causes, a transaminase value is approximately 1.5-fold above 
baseline (Day 0) OR is successively increasing during follow-up (at the Investigator’s 
discretion, they may choose to wait for a repeat transaminase value which remains 
elevated, or is further increased, or they may choose to initiate treatment); or
2. Vector-derived FIX:C activity levels decline without evidence of inhibitor, 
corticosteroids may be added at the discretion of the Investigator.
Oral corticosteroids (such as prednisolone/prednisone) will be used per the AASLD 
guidelines, with modification allowed by the Investigator and agreed by the medical monitor 
based on response to laboratory parameters and/or participant tolerance of the regimen:
Table 1.
Recommended Initial Regimen for Oral Corticosteroids
Schedule
Prednisolone/Prednisone (mg/day)
Week 1
~100 - 60
Week 2
60a
Week 3
40
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Table 1.
Recommended Initial Regimen for Oral Corticosteroids
Schedule
Prednisolone/Prednisone (mg/day)
Week 4
30
Week 5
30
Week 6
20b
Week 7
15
Week 8
10
a.
Please see paragraph below.
b.
Maintain at 20 mg/day until transaminases (and ELISPOT) return to baseline, then reduce by 5 mg/day 
until 10 mg/day are achieved then reduce by 2.5 mg/week up to 5 mg daily.
Approximately 100-60 mg/PO (orally) QD (once a day) of oral corticosteroids for the first 
week is recommended as the starting dose unless the Investigator believes a different 
regimen should be implemented based on the participant’s medical history.  Per the judgment 
of the Investigator, 60 mg/PO QD a can be extended to another week if the participant has no 
adverse effect.  The subsequent prednisolone/prednisone taper should not be started until the 
ALT and/or AST have begun to decline or have returned to approximately baseline (pre-
administration) levels.  See Table 1 above.
The following schedule of combined oral corticosteroids and IV corticosteroids 
(methylprednisolone) is recommended if there is no evidence of resolution of transaminase 
elevation while on oral corticosteroids treatment alone.
Table 2. Recommended Regimen for Combination Intravenous and Oral 
Corticosteroids
Schedule
Prednisolone/Prednisone (mg/day)
Methylprednisolone (g/day)
Day 1-3
n/a
1
Day 4-7
20
n/a
Week 2
60
n/a
Week 3
60
n/a
Week 4
40
n/a
Week 5
30
n/a
Week 6
30
n/a
Week 7
20
n/a
Week 8
10
n/a
Week 9
5
n/a
There is extensive experience with corticosteroids and immunosuppressive regimens in 
hemophilia: first, as a maneuver to eradicate antibodies to factor VIII or IX, clinically termed 
inhibitors43-45 and second, in the setting of liver transplantation due to the high prevalence of 
hepatitis C among adults with hemophilia46, 47.  Many individuals with hemophilia have been 
maintained on standard liver transplant immunosuppression regimens for years. 

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Corticosteroids have been used to treat people with asthma, idiopathic thrombocytopenic 
purpura, and other medical conditions for years. For participants with severe hemophilia B, 
the benefit of long-term expression of a modest level of clotting factor far outweighs the risk 
of a course of immunomodulatory drugs.
The Investigator will have flexibility in implementing the immunomodulatory regimen since 
the exact regimen and course will depend on clinical circumstances. The long-term side 
effects of the immunomodulatory drugs to be considered in this study are well characterized.  
Participants who develop immune hepatitis will be monitored closely to minimize the risk of 
the side effects.  To utilize the lowest effective dose and to shorten the duration of the 
immunosuppressive therapies, tapering of the regimen will start as soon as there is evidence 
of resolution of hepatic transaminases elevation and disappearance from the peripheral blood 
of capsid-specific T cells.  While on immunomodulatory regimens, participants will also be 
monitored for side effects, including opportunistic infections. Antibiotics or other 
medications to minimize the risk of opportunistic infection may be prescribed at the 
discretion of the Investigator. All events related to the use of immunomodulatory drugs (eg, 
hyperglycemia, weight gain, infections) will be recorded as adverse events connected to their 
use. 
If immune hepatitis develops in any participant, following investigational product 
administration and if 2 or more participants are non-responsive to immunomodulatory 
regimens, or if the value of the transaminases continue to rise, consideration of more 
intensive immunomodulatory regimens will be entertained per recommendation from the 
independent Data DMC.  Regimen recommendations will require agreement from the DMC, 
Sponsor Medical Monitor, and the Investigator.
4.1.6. Thrombotic Potential Assessments (ONLY for Participants Who Reach Vector-
derived FIX:C Activity Levels >150% after the infusion of PF-06838435)
Based on non-clinical studies in NHPs and the and the now closed Baxter study using hFIX-
Padua, it is not predicted that vector-derived FIX:C activity levels >150% of normal will be 
achieved in this study.  However, thrombin-antithrombin levels (TAT) as thrombotic 
potential will be measured if vector-derived FIX:C activity levels >150% of normal are 
achieved in any participant during the study.  Blood samples for TAT on Day 0 (prior to FIX 
protein product infusion) will be used to establish baseline value.
4.1.7. Duration of Study Participation
The study will consist of the following phases:
1. Screening period (up to 6 [±2] weeks);
2. Dosing day (Day 0);
3. Safety observation period (52 [±2] weeks post-infusion of PF-06838435).
The total duration of the study is approximately 58 weeks (including up to 6 weeks of 
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4.1.7.1. Screening Period
Potential participants will undergo the screening assessments described in the Schedule of 
Activities up to 6 (±2) weeks prior to the infusion of PF-06838435 once the consent process 
is completed at the vector-administration center. If the screening result of FIX:C activity 
level is >2% due to recent infusion of factor IX protein product, then the severity of 
hemophilia B may be confirmed by documented historical evidence from a certified 
laboratory demonstrating the FIX:C activity level ≤2% or from a documented genotype 
known to produce a clinically severe phenotype of hemophilia B. If FIX:C activity is not 
≤2% at screening or documented historical evidence is not available and genotype are not 
known, sample(s) will be drawn for analysis at Screening. Genotype is not a criterion for 
inclusion or exclusion. However, a documented genotype known to produce a clinically 
severe phenotype of hemophilia B is required if the participant is otherwise unable to 
demonstrate severity. Once the eligibility is verified, participants are required to undergo a 
washout of FIX protein products for at least 96 hours (4 days) prior to the Dosing Day (Day 
0) to establish baseline value of FIX:C and FIX inhibitor. The screening period may be 
extended up to 2 weeks for participants who have a bleeding event requiring FIX protein 
product infusion within 96 hours prior to Day 0 (Dosing Day). If screening is prolonged 
greater than 8 weeks, then the FIX inhibitor, anti-AAV-Spark100 capsid antibody, 
biochemistry, hematology, vital signs, and physical examination screening assessments must 
be repeated to ensure continued eligibility. The reason for prolongation of screening should 
be clearly documented.
Screening assessments would also be done to verify participant eligibility are described in
Section 8.10.1.
4.1.7.2. Dosing Day
Assessments and procedures to be performed on Dosing Day (Day 0) are described in the 
Schedule of Activities.  Participants will receive a bolus infusion of FIX protein product in 
about 10 minutes for FIX incremental recovery (Section 6.1.1) followed by a single IV
infusion of PF-06838435 at the vector-administration center.  The complete dose of 
PF-06838435 will be infused via infusion pump over a period of approximately 60 minutes 
under medical supervision.  Vital signs will be taken at various time-points up to 
approximately 24 hours from the start of infusion (see Schedule of Activities).
Blood samples for FIX incremental recovery will be collected pre-infusion of the FIX protein 
product, 10 (±2) minutes [end-of-infusion], 1 hour ± 10 minutes, 3 hours ± 10 minutes, 
6 hours ± 10 minutes, and 24 (±1) hours from the start-of-infusion. Samples for thrombin 
generation assessments will also be collected pre-infusion and 10 (±2) minutes from the start-
of-infusion of FIX protein infusion and evaluated by an 
 performed at the 
central laboratory.  For participants at selected sites, depending on the testing capabilities, 
additional samples for global hemostasis such as whole blood TEG and/or ROTEM may also 
be collected pre-infusion and 10 (±2) minutes from the start-of-infusion of FIX protein 
infusion and evaluated locally.
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4.1.7.3. Post-Infusion
Participants will report to either the vector-administration center or follow-up center for 
safety evaluations, according to the protocol assessments (See the Schedule of Activities for 
further details regarding each visit), for up to 52 (±2) weeks after infusion of PF-06838435. 
During the safety observation period, in-home service provider can be utilized, if needed, for 
mobile-phlebotomy and sample-collection services during the visits which do not require a 
physical examination.
4.2. Scientific Rationale for Study Design
This study will investigate up to three PF-06838435 dose levels (5x1011, 1x1012, and 2x1012
vg/kg). Safety of these dose levels is supported by previous human clinical trials of AAV2 
and AAV8 vectors encoding hFIX, as well as the NHP studies with AAV-Spark100-hFIX19-
Padua and with SPK-9001, in which dose levels up to 5x1012 vg/kg were infused without 
evidence of adverse effects. 
Dose escalation and dose level expansion strategies are employed in the study based on 
vector-derived FIX activity levels as well as any immune responses against AAV capsid.  
The primary study objective is the assessment of safety and tolerability of a single IV
infusion of PF-06838435. This study also aims to characterize kinetics of PF-06838435. The 
vector-derived endogenous (not affected by intercurrent FIX product infusions) FIX:C 
activity levels will be characterized by post-treatment population mean. The assessment will 
be done for each dose of PF-06838435. 
As no formal hypotheses will be tested in this study, the sample size is based on the need to 
establish the initial safety and kinetic profile of PF-06838435. Up to 20 evaluable 
participants will be dosed in the study (Section 9.3).
4.3. Justification for Dose
Non-clinical pharmacology, toxicology, and biodistribution studies of AAV-Spark100-
hFIX19-Padua have been performed in three animal models (wild-type [WT] mice, HB mice, 
and NHPs) to evaluate expression and safety.  PF-06838435 has also been infused into NHP 
and demonstrated to drive expression of FIX at levels equivalent to AAV-Spark100-hFIX19-
Padua.  Long-term safety and immunogenicity of the FIX-Padua protein were evaluated in a 
hemophilic canine model using an AAV8-FIX-Padua vector. These data are relevant to PF-
06838435 since FIX gene delivery using AAV-Spark100 results in similar levels of 
expression as compared to gene delivery using AAV8 in these species.  Based on the 
Sponsor’s experience, studies in mice have not been predictive of FIX expression levels in 
humans, but studies in dogs and NHPs have correlated well with levels in human participants.  
The non-clinical studies in NHP using AAV Spark100-hFIX19-Padua infused at a dose of 
1x1012 vg/kg resulted in steady-state vector-derived FIX activity levels of ~27% (range 22.7 
30.7%).
A dose of 5x1012 vg/kg was administered without evidence of adverse effects in NHPs.  It is 
widely accepted that maintaining factor activity levels above 1-2% of normal may prevent 
bleeding and ultimately arthropathy in patients with severe hemophilia48, 49.  Based on large 

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animal models of the disease and prior clinical experience with AAV8-hFIX19, the starting 
dose of 5x1011 vg/kg may result in detectable circulating vector-derived factor IX (FIX:C) 
activity levels above background levels.  This starting clinical dose (5x1011 vg/kg) is ~10 fold 
lower than the highest dose studied in the Good Laboratory Practice (GLP) toxicology study.  
Furthermore, non-clinical safety data demonstrate that doses of 1x1012 vg/kg, 2x1012 vg/kg 
and 5x1012 vg/kg are generally well tolerated in NHPs and support the proposed up to three 
dose levels of 5x1011, 1x1012, and 2x1012 vg/kg to be investigated in this study.
It is worth noting that the preliminary data of an ongoing Baxter trial (NCT#01687608) using 
self-complementary AAV8-hFIX-Padua (BAX-335), presented at the 8th Annual Congress 
of the EAHAD on 12th February 2015 in Helsinki, Finland, showed vector-derived FIX:C 
activity levels of ranging from <1 – 60% at doses of 2 x1011 vg/kg, 1x102 vg/kg and 3x102
vg/kg with no safety concerns6.  One common aspect of our previous trial (IND 9398) and 
Baxter’s study is that vector preparations with minimal empty capsid content were used50, 51. 
The outcome of both trials in the low dose levels was disappointing, showing sub-therapeutic 
or no FIX expression in most of the participants. Specifically, three out of three participants 
treated with 4x1011 vg/kg of AAV2-hFIX16 and one out of two participants treated with 
2x1011 vg/kg of BAX-335 manifested no detectable factor IX expression. Activity levels 
from the second participant dosed with BAX-335 could only be detected due to the 
hyperactivity of the Padua variant as antigen levels may not have been higher than 0.25 -
0.5% of normal.
Meanwhile, both participants infused with 2x1011vg/kg of scAAV2/8-LP-hFIXco with an 
empty:full capsid ratio of approximately 5:152 in the SJ-UCL hemophilia B trial expressed 
FIX above background levels5.  Thus, the Sponsor hypothesizes the presence of an excess of 
empty capsids may absorb low-level NAbs and non-NAbs, permitting liver transduction after 
peripheral vector infusion even at low doses53.  PF-06838435 will contain a mixture of empty 
and full capsid particles (cp), at a ratio comparable to the ratio used in the SJ-UCL study.
Additional information for the C0371005 Phase 1/Phase 2a study results may be found in the 
Investigator’s Brochure (IB).
 
 
 
 
 
 
 
 
 
 
 
4.3.1. Study Stopping Rules
Pfizer may terminate this study at any time after informing the Investigators.  Pfizer, or 
designee, will notify the Investigator(s) and appropriate regulatory authorities if the study is 
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suspended, terminated or completed.  If the study is suspended or terminated, the following 
instructions should be followed, unless the DMC and/or the Study Medical Monitor advise 
otherwise:
1. Participants who have already received PF-06838435 will continue to maintain the 
protocol schedule of activities; 
2. Participants who have already enrolled into the study but have not received 
PF-06838435 will wait for DMC recommendation.  The scheduled date for 
PF-06838435 infusion may be postponed or cancelled.
The occurrence of any of the following medically important events will result in suspension 
of further enrollment while the events are under investigation:

Any drug-related death during the study;

Any participant develops drug-related or possibly drug-related Grade III-IV toxicity 
such as FIX inhibitor, allergic reaction (bronchospasm and anaphylaxis), excluding 
elevated transaminases;

Any participant develops drug-related or possibly drug-related Grade III-IV elevated 
transaminases that fails to improve or resolve within four weeks on the 
immunosuppressive regimens; 

Any participant develops drug-related or possibly drug-related Grade IV (>10-fold) 
elevated transaminases;

Any participant reaches >150% of normal vector-derived FIX:C activity levels and 
develops drug-related or possibly drug-related thrombotic event after vector infusion 
(with the exception of IV infusion-site thrombophlebitis) or if any participant
develops a sustained (defined as > 6 weeks) FIX activity levels of >150%;

Participant experience a medically important event that warrants further evaluation;

Any occurrence of a malignancy at any point after vector infusion that is possibly, 
probably, or definitely related to the investigational product.
It is important to note that AAV vector-mediated insertional mutagenesis, if it should occur, 
is not likely to be observed in the first year after gene transfer; therefore, Pfizer intends to 
provide long-term safety monitoring of participants in the extension study.
In addition to halting enrollment, such an event will be handled as a serious adverse event 
(SAE) and reported in the time frame according to Section 8.3.1.1 (Reporting of SAEs to 
Pfizer) of the protocol. The DMC will review data relevant to the event and will receive 
input from Pfizer and/or Investigator before providing appropriate recommendations.  The 
event and the DMC’s recommendation will be discussed with the U.S. Food and Drug 
Administration (FDA) and other regulatory authorities prior to re-initiation of enrollment.  

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All participants who were infused with the investigational product will continue to comply 
with the follow-up schedule according to the protocol.
4.4. End of Study Definition
A participant is considered to have completed the study if he has completed all phases of the 
study including the last scheduled procedure shown in the Schedule of Activities.
The end of the study is defined as the date of the last scheduled procedure shown in the 
Schedule of Activities for the last participant in the trial globally. 
If a decision is made to terminate the study, the Investigators will be notified. No additional 
participants will be enrolled or dosed and the appropriate end-of-study assessments will be 
performed for all participants enrolled in the study at that time.
At the time of last subject last visit (LSLV), final assessment results and laboratory tests are 
generally not available, thereby necessitating the need for follow-up action.  Sponsor studies 
involve specialized tests, which have to be sent to specialized centers; these data then have to 
be reconciled with the rest of the data.  Thus, clinical sites are still active post-LSLV and 
may only be closed following database lock, when all required participant information has 
been confirmed as both received and clean, including follow-up information for any 
SAEs/reactions.
4.5. Extension Study (C0371003)
Participants who complete study assessments at the defined end of study will be encouraged 
to enroll in C0371003 evaluating the long-term safety, durability, and efficacy of 
PF-06838435.  A 5-year long-term follow-up (LTFU) is planned based on the November 
2006 FDA Guidance entitled Gene Therapy Clinical Trials – Observing Participants for 
Delayed Adverse Events54. The Investigator should discuss the extension plan with the 
participants prior to enrolling them in this study and again at the End-of-Study (Week 52) 
visit. Any AEs, safety events or unscheduled visits between Week 52 (or End-of-Study) of 
this study and the first study visit of the extension study will be captured in the source data 
for the subject and entered into the extension study database after the subject has agreed and 
completed the informed consent process.
5. STUDY POPULATION
Prospective approval of protocol deviations to recruitment and enrollment criteria, also 
known as protocol waivers or exemptions, is not permitted.
5.1. Inclusion Criteria
Participants are eligible to be included in the study only if all of the following criteria apply:
Age
1. Participant must be male and ≥18 years of age inclusive, at the time of signing the 
informed consent.

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Type of Participant and Disease Characteristics
2. Have hemophilia B with ≤2 IU/dL (≤2%) endogenous FIX activity levels as documented 
from a certified clinical laboratory at the time of screening.  If the screening result is >2% 
due to insufficient washout from the FIX product, then the severity of hemophilia B may 
be confirmed by documented historical evidence from a certified clinical laboratory 
demonstrating ≤2% FIX coagulant activity (FIX:C) or from a documented genotype 
known to produce clinically severe phenotype of hemophilia B;
3. Have had ≥50 prior exposure days (EDs) to any recombinant and/or plasma-derived FIX 
protein products based on historical data from participant's records/history;
4. a) Prophylaxis participants:  Have had bleeding events and/or infusion with FIX products 
during the last 12 weeks, as documented in the participants' medical records; or
1. b) On-demand participants: Have had ≥4 bleeding events in the last 52 weeks and/ or 
chronic hemophilic arthropathy (pain joint destruction and loss of range of motion) in one 
or more joints;
5. Have no history of hypersensitivity or anaphylaxis associated with any FIX or IV 
immunoglobulin administration;
6. Have no measurable FIX inhibitor as assessed by the central laboratory; or documented 
no prior history of FIX inhibitor after 50 EDs (family history of inhibitors will not 
exclude the participant) and no clinical signs or symptoms of decreased response to FIX 
administration;
7. Have acceptable laboratory values sampled at screening and reviewed prior to Day 0:

Hemoglobin ≥11 g/dL;

Platelets ≥100,000 cells/µL;

AST, ALT, alkaline phosphatase ≤2x upper limit of normal (ULN);

Bilirubin ≤3x ULN (Bilirubin levels above the laboratory's normal range are 
acceptable in individuals with a documented history or laboratory evidence of 
Gilbert's Disease);

Creatinine ≤2.0 mg/dL.     

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Sex
8. Male 
Contraceptive use by men should be consistent with local regulations regarding the methods 
of contraception for those participating in clinical studies.
Male participants are eligible to participate if they agree to the following during the 
intervention period and for at least time required for 3 consecutive ejaculate samples to test 
negative for vector shedding:

Refrain from donating sperm.
PLUS either:

Be abstinent from heterosexual or homosexual intercourse as their preferred and usual 
lifestyle (abstinent on a long term and persistent basis) and agree to remain abstinent.
OR

Must agree to use contraception/barrier as detailed below:
Agree to use male condom when engaging in any activity that allows for passage of ejaculate 
to another person 
Informed Consent
9. Capable of giving signed informed consent as described in Appendix 1 which includes 
compliance with the requirements and restrictions listed in the Informed Consent Form
(ICF) and in this protocol
5.2. Exclusion Criteria 
Unless otherwise specified, participants who meet any of the following criteria at screening 
or prior to dosing of PF-06838435 (Day 0) are not eligible for the study. See Section 8.10 for 
additional study assessments:
1. Hepatitis B screening (acute and chronic):

A participant who has either Hepatitis B surface antigen (HBsAg) assessment which 
is positive, or HBV-DNA is positive/detectable.

A participant who is currently undergoing anti-viral therapy for hepatitis B.
2. Hepatitis C screening (acute or chronic):

A participant who is currently undergoing anti-viral therapy for chronic hepatitis C

A participant is not eligible if his HCV-RNA load assay result is positive/detectable.

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3. Significant underlying liver disease.
•
A participant is not eligible if any of the following pre-existing diagnoses, which are 
indicative of significant underlying liver disease, are present in the medical record:
•
Portal hypertension, or;
•
Splenomegaly; or
•
Hepatic encephalopathy.
•
All participants who do not have the listed pre-existing diagnoses in (1) must have the 
following assessments performed at Screening:
•
A participant is not eligible if the serum albumin level is below the testing 
laboratory’s lower limit of normal; and
•
At least one of the following diagnostic tests for liver fibrosis indicates ≥stage 3.  
The following results are indicative of fibrosis ≥stage 3 and exclude the 
participant from participation:
•
FibroScan, with a score >8.3 kPa units 
•
FibroTest/FibroSURE with a result >0.48; or
•
AST-to-Platelet Ratio Index (APRI) >1. 
4. Have serological evidence of HIV-1 or HIV-2 with CD4 counts ≤200/mm3. Participants 
who are HIV-positive and stable, have an adequate CD4 count (>200/mm3) and 
undetectable viral load (<50 gc/mL) documented in prior medical records and at 
Screening, and are on an antiretroviral drug regimen are eligible to enroll;
5. Participants receiving 5x1011 vg/kg with anti-AAV-Spark100 neutralizing antibody titers 
≥1:5; 
 
 
 
 
6. Have history of chronic infection or other chronic disease that the Investigators consider 
to constitute an unacceptable risk;
7. Have been dosed in a previous gene therapy research trial within the last 52 weeks or 
enrolled in a clinical study with an investigational drug within the last 12 weeks
8. Any concurrent clinically significant major disease, or other unspecified reasons that, in 
the opinion of the Investigator, and/or Sponsor makes the participant unsuitable for 
participation in the study; and
9. Unable or unwilling to comply with the schedule of visits and study assessments 
described in the clinical protocol.     
CCI

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5.3. Lifestyle Considerations
Participants are expected to remain compliant with inclusion criterion 8 at least until 
3 consecutive ejaculate samples test negative for vector shedding.
One subject was noted to have increased liver function tests (LFTs) in the setting of 
excessive alcohol consumption in the long term follow up period.  Upon discontinuation of 
alcohol, his LFTs normalized but was later noted to have a decline in his steady state FIX 
activity level.  While this was a single episode and a definitive conclusion cannot be drawn, it 
supports monitoring of alcohol consumption during the study.  Participants who report 
increased alcohol consumption should have at a minimum LFTs and FIX activity monitored.
5.4. Screen Failures
Screen failures are defined as participants who consent to participate in the clinical study but 
are not subsequently entered in the study. A minimal set of screen failure information is 
required to ensure transparent reporting of screen failure participants to meet the 
Consolidated Standards of Reporting Trials (CONSORT) publishing requirements and to 
respond to queries from regulatory authorities. Minimal information includes demography, 
screen failure details, eligibility criteria, and any SAE.
Individuals who do not meet the criteria for participation in this study (screen failure) may be 
rescreened in consultation and with the agreement of the medical monitor.
6. STUDY INTERVENTION
Study intervention is defined as any investigational intervention(s), marketed product(s), 
placebo, or medical device(s) intended to be administered to a study participant according to 
the study protocol.
6.1. Study Intervention(s) Administered
Refer to investigational product (IP) manual for specifics on the preparation, storage, 
handling, disposal, and accountability of investigational product.
ARM Name
PF-06838435/Fidanacogene elaparvovec 
Intervention 
Name
PF-06838435/Fidanacogene elaparvovec
Type 
Gene Therapy
Dosage Form
Injectable
Strength
1.00 x 1013 vg/mL
This is the nominal strength.  The actual strength for each lot will be 
provided for dose calculation
Dosage
5x1011 vg/kg single administration
1x1012 vg/kg single administration 
2x1012 vg/kg single administration 
For participants with body mass index (BMI) exceeding 30 kg/m2, the 
study dose will be calculated based on an adjusted body weight 

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determination that assumes a maximum permissible BMI of 30 kg/m2.  
For example, a subject who is 6’2” and weighs 370 pounds (BMI 47.5 
kg/m2) would receive a vector dose based on an adjusted body weight of 
234 pounds (which is the body weight associated with a BMI of 30 
kg/m2 for a 6’2” individual).
Route of 
Administration
Intravenous infusion/injection
IMP and NIMP
IMP (investigational medicinal product)
Sourcing
Provided centrally by the Pfizer
Packaging and 
Labeling
Study Intervention will be provided in a 2 mL vial Each vial will be 
labeled as required per country requirement.
Current/Former 
Names
PF-06838435, 
SPK-9001, 
AAV Spark100 hFIX39-Padua,
Adeno associated viral vector with human factor IX Padua gene.
6.1.1. Dose Schedule and Administration
Refer to Figure 1 for the Study Schematic and Study Specifics (Section 4.1.1) for a 
description of the sequence of enrollment.  Following the bolus infusion of the participant’s 
usual FIX protein product in about 10 minutes for FIX incremental recovery, the participant
will be infused with PF-06838435 IV for approximately 60 minutes via infusion pump.  The 
rate of administration should be determined based on the total volume of the PF-06838435 
required for the participant to infuse for approximately 60 minutes.
6.1.2. FIX Incremental Recovery of FIX Products
Participants should be reminded to have washout of at least 96 hours (4 days) without FIX 
protein product, or longer washout for extended half-life FIX protein product, prior to any 
blood draw and infusion on Day 0. On Day 0 participants will be infused with 100 IU/kg of 
their usual FIX protein product over 10 (±2) minutes, under the supervision from the site 
staff and/or Investigator(s) to assess FIX incremental recovery.  Number of vials, total 
volume, and total dosage are monitored and recorded by the site staff.
6.2. Preparation/Handling/Storage/Accountability
The investigational product must be stored in a secure location.  Accountability for the study 
drug is the responsibility of the Investigator.  More details concerning this responsibility are 
included in the IP Manual.  The Investigator or his/her designee is responsible for the proper 
dispensing of the investigational product.  The IP is to be dispensed only to participants who 
are enrolled and eligible based on the inclusion and exclusion criteria in this study.  IP vials 
are for one time use only; any IP remaining in the vial after infusion should not be used for 
another subject.
Study site staff and investigational pharmacy personnel should refer to the Pharmacy 
Brochure for specific instructions on the handling, preparation, administration, and disposal
of the investigational product.

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1. The investigator or designee must confirm appropriate temperature conditions have 
been maintained during transit for all study intervention received and any 
discrepancies are reported and resolved before use of the study intervention.
2. Only participants enrolled in the study may receive study intervention and only 
authorized site staff may supply or administer study intervention. All study 
intervention must be stored in a secure, environmentally controlled, and monitored 
(manual or automated) area in accordance with the labeled storage conditions with 
access limited to the investigator and authorized site staff.
3. The investigator, institution, or the head of the medical institution (where applicable) 
is responsible for study intervention accountability, reconciliation, and record 
maintenance (ie, receipt, reconciliation, and final disposition records).
4. Further guidance and information for the final disposition of unused study 
interventions are provided in the IP Manual.
Ordering the IP and Preparation: Details are provided in the IP Manual and it should be 
reviewed carefully.  Once eligibility has been confirmed, the IP can be ordered noting that 
will take at least 3 weeks for product delivery
6.3. Measures to Minimize Bias: Randomization and Blinding
6.3.1. Screening of Participants
Participants must provide consent before any screening tests or assessments are performed.  
At the time of consent, the participant will be enrolled into the study.  Participating study 
sites are required to document all screened candidates initially considered for inclusion in 
this study.  If a participant is excluded from the study, the reasons for exclusion will be 
documented in the participant’s source documents and on the screening log.
Participants may have screening laboratory results repeated once if the initial test falls 
outside of the protocol criteria. At the second screening, the participant will be assigned a 
different participant identification number.
For participants whose genotype is not known, a sample will be drawn for analysis at 
screening.  This is not an inclusion or exclusion criterion; the participant’s refusal to have 
this genotype sample taken would not exclude the participant from the study unless the 
severity of the disease is unable to be verified due to inadequate washout.
Genotyping may provide information regarding the predisposition of genotypic 
subpopulations to experience different bleeding frequencies.  The development of an 
inhibitor to treatment with factor concentrates is the single most serious complication of 
factor replacement.  One of the decisive risk factors for the development of inhibitors is the 
type of mutation (eg, deletion or missense) that codes for a protein that may be absent, 
truncated, or present, but not functional.  There is a correlation between the resultant protein 
and the likelihood of developing inhibitors to factor replacement55.

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6.3.2. Enrollment of Participants
Each participant will be assigned a unique participant identification number after the 
informed consent process is completed.  No participant may be dosed prior to obtaining the 
unique participant identification number.  The Investigator must confirm and verify the 
eligibility per criteria in Section 5.1 and Section 5.2 (following the review of screening 
results from the certified clinical laboratory and other documents).  Participant identification 
numbers that are assigned will not be reused even if the participant does not receive 
investigational product or fails screening.
6.3.3. Randomization
Not applicable.  This is a non-randomized study.
6.3.4. Blinding Procedures
Not applicable.  This is an open-label study.
6.4. Study Intervention Compliance
Deviation(s) from the prescribed dosage regimen should be recorded in the electronic case 
report form (eCRF).
Compliance with the infusion of FIX protein product and PF-06838435 on Day 0 is to be 
monitored and recorded by site staff.
After the infusion of FIX protein product on Day 0, participants will immediately be infused 
with PF-06838435.  PF-06838435 will be infused via infusion pump and will be supervised 
by the investigational staff.  The vial lot number, total volume, and infusion time are 
monitored and recorded by the site staff.  Therefore, full compliance with PF-06838435 
infusion is anticipated.
6.5. Concomitant Therapy
The use of concomitant therapies or procedures, as defined below, must be recorded on the 
participant’s eCRF, according to instructions for eCRF completion.  AEs related to 
administration of these therapies or procedures must be documented on the appropriate 
eCRF.
A concomitant therapy is any drug or substance administered between participant consent (at 
Screening) and last study visit.  Participants taking medication routinely for a pre-existing 
condition should be on a regimen, which has been stable for at least 3 weeks, and dosage 
changes should not be anticipated during the post-infusion period for this study.  All 
concurrent prescription and non-prescription medications, including over-the-counter and 
alternative preparations (including herbal remedies, vitamins, and health food supplements), 
should be recorded at baseline and throughout the study period.
Medication use in the 30 days prior to screening, as well as the use of concomitant therapies 
or procedures must be recorded on the participant’s eCRF, according to instructions for 

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eCRF completion.  AEs related to administration of these therapies or procedures must be 
documented on the appropriate eCRF.
6.5.1. Allowed Therapy
During the study participants are requested to temporarily suspend their prophylaxis regimen, 
but participants may take:

FIX product, as needed.  Usage of clotting factors (product, date, dosage, reason) will 
be recorded in the infusion log.
Participant should be instructed to discuss any new medications, including non-prescription 
drugs and herbal preparations, with the Investigator prior to taking them.
Other therapies considered necessary for the participant’s welfare may be given at the 
discretion of the Investigator.  All such therapies must be recorded in the eCRF.
6.5.2. Disallowed Therapy
The following concomitant medications are not permitted during the study:
1. Blood products such as red blood cells (RBC), platelets, and fresh frozen plasma, except 
as required during a surgery.
2. Non-steroidal anti-inflammatory drugs that are known to inhibit platelet function, for 
example naproxen, aspirin, ibuprofen. 
3. Acetylsalicylic acid (aspirin) or ibuprofen; however, other non-steroidal anti-
inflammatory drugs are permitted.
4. Participants who are participating in other investigational therapies and concomitantly 
used with PF-06838435.
5. Any other therapies under investigation and concomitantly used with the investigational 
product (participants are not allowed to participate concurrently in another clinical study).
6.5.3. Concomitant Procedures
A concomitant procedure is any therapeutic intervention (eg, surgery/biopsy, physical 
therapy) or diagnostic assessment (eg, blood gas measurement, bacterial cultures) performed 
between the time the participant is enrolled (at screening) and last study visit.  Concomitant 
procedures must be recorded in the eCRF
6.6. Dose Modification
No more than a single dose of the study treatment will be administered during this study.
The dose of 1×1012 and 2×1012 vector genomes/kg body weight will be modified for a 
participant with BMI >30 kg/m2 (See the table in Section 6.1).

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6.7. Intervention after the End of the Study
No further intervention is planned after the end of the study.
7. DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL
7.1. Discontinuation of Study Intervention
Since no more than the single infusion of PF-06838435 on Day 1 will be administered during 
the study, this section is not applicable. 
See the Schedule of Activities (SoA) for data to be collected at the time of intervention 
discontinuation and follow-up and for any further evaluations that need to be completed.
7.2. Participant Discontinuation/Withdrawal from Study

A participant may withdraw from the study at any time at his/her own request, or may 
be withdrawn at any time at the discretion of the investigator for safety, behavioral, 
compliance, or administrative reasons. This is expected to be uncommon.

At the time of discontinuing from the study, if possible, an early discontinuation visit 
should be conducted. All assessments outlined for Week 52 visit should be 
completed. See SoA for data to be collected at the time of study discontinuation and 
follow-up and for any further evaluations that need to be completed.

The participant will be permanently discontinued both from the study intervention 
and from the study at that time.

If the participant withdraws consent for disclosure of future information, the sponsor 
may retain and continue to use any data collected before such a withdrawal of 
consent.

If a participant withdraws from the study, he/she may request destruction of any 
remaining samples but data already generated from the samples will continue to be 
available, and may be used to, to protect the integrity of existing analyses. The 
investigator must document any such requests in the site study records.

When a participant withdraws from the study because of an SAE, the SAE must be 
recorded on the CRF and reported on the CT (clinical trial) SAE Report.
If a participant withdraws from the study after enrollment, but before receiving a dose of the 
investigational product (PF-06838435), then follow-up beyond the screening evaluations is 
not required.  Withdrawn participants without receiving a dose of the investigational product 
will be replaced.
7.3. Lost to Follow up
A participant will be considered lost to follow-up if he or she repeatedly fails to return for 
scheduled visits and is unable to be contacted by the study site.

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The following actions must be taken if a participant fails to return to the clinic for a required 
study visit:

The site must attempt to contact the participant and reschedule the missed visit as 
soon as possible and counsel the participant on the importance of maintaining the 
assigned visit schedule and ascertain whether or not the participant wishes to and/or 
should continue in the study.

Before a participant is deemed lost to follow up, the investigator or designee must 
make every effort to regain contact with the participant (where possible, 3 telephone 
calls and, if necessary, a certified letter to the participant’s last known mailing 
address or local equivalent methods). These contact attempts should be documented 
in the participant’s medical record.

Should the participant continue to be unreachable, he/she will be considered to have 
withdrawn from the study. 
Discontinuation of specific sites or of the study as a whole are handled as part of 
Appendix 1.
8. STUDY ASSESSMENTS AND PROCEDURES

Study procedures and their timing are summarized in the SoA. Protocol waivers or 
exemptions are not allowed.

Immediate safety concerns should be discussed with Pfizer immediately upon 
occurrence or awareness to determine if the participant should continue or 
discontinue study intervention.

Adherence to the study design requirements, including those specified in the SoA, is 
essential and required for study conduct.

All screening evaluations must be completed and reviewed to confirm that potential 
participants meet all eligibility criteria. The investigator will maintain a screening 
log to record details of all participants screened and to confirm eligibility or record 
reasons for screening failure, as applicable.

Procedures conducted as part of the participant’s routine clinical management (eg, 
blood count) and obtained before signing of the ICF may be utilized for screening or 
baseline purposes provided the procedures met the protocol-specified criteria and 
were performed within the time frame defined in the SoA.
8.1. Efficacy Assessments
No formal efficacy evaluations will be performed.  However, the following information will 
be collected for exploratory efficacy evaluations:

Vector-derived FIX:C activity levels (including peak and steady-state levels)

FIX antigen level 

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
Annualized bleed rate (ABR) (spontaneous and traumatic)

Annualized factor IX consumption 

Health-economic parameters (Section 8.9)

Number of target joints (Section 8.10.3)

Health-related quality-of-life (Section 8.10.4)

Changes in level of activity (Section 8.10.5)
8.2. Safety Assessments
Planned time points for all safety assessments are provided in the SoA.
8.2.1. Physical Examinations
Physical examination including height and weight. 
8.2.2. Vital Signs
Vital sign measurements including blood pressure, pulse rate, respiratory rate, and 
temperature (°C/°F), and should be taken after the subject has been resting supine or upright 
for 5 minutes.
8.2.3. Electrocardiograms
Electrocardiograms (ECG) for participants >50 years of age or if clinically indicated.
8.2.4. Clinical Safety Assessments

Hemophilia medical history for the 26 weeks preceding screening.

Target joint history for the 52 weeks preceding screening.  Target joints will be identified 
and assessed during this study.  A target joint is defined as a major joint (eg, hip, elbow, 
wrist, shoulder, knee, ankle) into which repeated bleeding occurs (frequency of 3 or more 
bleeding episodes into the same joint in a consecutive 12 week period) and with 
symptoms of pre-existing target joint involvement (eg, synovitis, persistent swelling, 
effusion, limitation of range of motion) (Ota et al. 2007).

Assessment for adverse signs and symptoms (AE and SAE recording) and concomitant 
medications

Concomitant therapy and procedures
8.2.5. Clinical Safety Laboratory Assessments

See Appendix 2 for the list of clinical laboratory tests to be performed and to the 
SoA for the timing and frequency.

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
The investigator must review the laboratory report, document this review, and 
record any clinically relevant changes occurring during the study in the AE section 
of the CRF. The laboratory reports must be filed with the source documents. 
Clinically significant abnormal laboratory findings are those which are not 
associated with the underlying disease, unless judged by the investigator to be more 
severe than expected for the participant's condition.

All laboratory tests with values considered clinically significantly abnormal during 
participation in the study or within 52 ± 2 weeks after the last dose of study 
intervention should be repeated until the values return to normal or baseline or are 
no longer considered clinically significant by the investigator or medical monitor.

If such values do not return to normal/baseline within a period of time judged 
reasonable by the investigator, the etiology should be identified and the sponsor
notified.

All protocol-required laboratory assessments, as defined in Appendix 2, must be 
conducted in accordance with the laboratory manual and the SoA.

If laboratory values from non-protocol specified laboratory assessments 
performed at the institution’s local laboratory require a change in participant 
management or are considered clinically significant by the investigator (eg, SAE 
or AE or dose modification), then the results must be recorded in the CRF.
8.3. Adverse Events and Serious Adverse Events
The definitions of an AE or SAE can be found in Appendix 3.
AE will be reported by the participant (or, when appropriate, by a caregiver, surrogate, or the 
participant's legally authorized representative).
The investigator and any qualified designees are responsible for detecting, documenting, and 
recording events that meet the definition of an AE or SAE and remain responsible to pursue 
and obtain adequate information both to determine the outcome and to assess whether it 
meets the criteria for classification as an SAE, or that caused the participant to discontinue 
the study (Section 7.2)
In addition, the investigator may be requested by Pfizer Safety to obtain specific follow-up 
information in an expedited fashion. 
8.3.1. Time Period and Frequency for Collecting AE and SAE Information
The time period for actively eliciting and collecting AEs and SAEs (“active collection 
period”) for each participant begins from the time the participant provides informed consent, 
which is obtained before the participant’s participation in the study (ie, before undergoing 
any study-related procedure and/or receiving investigational product), through and including 
last study visit.

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For participants who are screen failures, the active collection period ends when screen failure 
status is determined.
Medical occurrences that begin before the start of study intervention but after obtaining 
informed consent will be recorded on the Medical History/Current Medical Conditions 
section of the case report form (CRF) not the AE section.
Follow up by the investigator continues throughout and after the active collection period and 
until the event or its sequelae resolve or stabilize at a level acceptable to the investigator, and 
Pfizer concurs with that assessment.
Investigators are not obligated to actively seek AE or SAE after conclusion of the study 
participation. However, if the investigator learns of any SAE, including a death, at any time 
after a participant has been discharged from the study, and he/she considers the event to be 
reasonably related to the study intervention or study participation, the investigator must 
promptly notify the sponsor. 
8.3.1.1. Reporting SAEs to Pfizer Safety 
All SAEs occurring in a participant during the active collection period are reported to Pfizer 
Safety on the CT SAE Report Form immediately and under no circumstance should this 
exceed 24 hours, as indicated in Appendix 3. The investigator will submit any updated SAE 
data to Pfizer within 24 hours of it being available.
All SAEs occurring in a participant during the active collection period are reported to Pfizer 
Safety on the CT SAE Report Form.
SAEs occurring in a participant after the active collection period has ended are reported to 
Pfizer Safety if the investigator becomes aware of them; at a minimum, all SAEs that the 
investigator believes have at least a reasonable possibility of being related to investigational 
product must be reported to Pfizer Safety.
8.3.1.2. Recording Non-serious AEs and SAEs on the CRF
During the active collection period, both non-serious AEs and SAEs are recorded on the CRF.
8.3.2. Method of Detecting AEs and SAEs
The method of recording, evaluating, and assessing causality of AE and SAE and the 
procedures for completing and transmitting SAE reports are provided in Appendix 3.
Care will be taken not to introduce bias when detecting AEs and/or SAEs. Open-ended and 
non-leading verbal questioning of the participant is the preferred method to inquire about 
AE occurrences.
8.3.3. Follow-up of AEs and SAEs
After the initial AE/SAE report, the investigator is required to proactively follow each 
participant at subsequent visits/contacts. For each event, the investigator must pursue and 

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obtain adequate information until resolution, stabilization, the event is otherwise explained, 
or the participant is lost to follow-up (as defined in Appendix 3).
In general, follow-up information will include a description of the event in sufficient detail to 
allow for a complete medical assessment of the case and independent determination of 
possible causality.  Any information relevant to the event, such as concomitant medications 
and illnesses, must be provided.  In the case of a participant death, a summary of available 
autopsy findings must be submitted as soon as possible to Pfizer Safety. 
Further information on follow-up procedures is given in Appendix 3.
8.3.4. Regulatory Reporting Requirements for SAEs

Prompt notification by the investigator to the sponsor of a SAE is essential so that 
legal obligations and ethical responsibilities towards the safety of participants and 
the safety of a study intervention under clinical investigation are met.

The sponsor has a legal responsibility to notify both the local regulatory authority 
and other regulatory agencies about the safety of a study intervention under clinical 
investigation. The sponsor will comply with country-specific regulatory 
requirements relating to safety reporting to the regulatory authority, institutional 
review boards (IRB)/independent ethics committees (IEC), and investigators.

Investigator safety reports must be prepared for suspected unexpected serious 
adverse reactions (SUSAR) according to local regulatory requirements sponsor 
policy and forwarded to investigators as necessary.

An investigator who receives an investigator safety report describing a SAE or other 
specific safety information (eg, summary or listing of SAEs) from the sponsor will 
review and then file it along with the Investigator’s Brochure and will notify the 
IRB/IEC, if appropriate according to local requirements.
8.3.5. Exposure During Pregnancy or Breastfeeding, and Occupational Exposure
Exposure to the investigational product under study during pregnancy or breastfeeding and 
occupational exposure are reportable to Pfizer Safety within 24 hours of investigator 
awareness.
8.3.5.1. Exposure During Pregnancy

Details of all pregnancies in female partners of male participants will be collected 
after the start of study intervention and until end of study participation.

If a pregnancy is reported, the investigator should inform the sponsor within 24 
hours of learning of the pregnancy and should follow the procedures outlined in
Appendix 4.

Abnormal pregnancy outcomes (eg, spontaneous abortion, fetal death, stillbirth, 
congenital anomalies, ectopic pregnancy) are considered SAEs.

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8.3.5.2. Exposure During Breastfeeding
Scenarios of exposure during breastfeeding must be reported, irrespective of the presence of 
an associated SAE, to Pfizer Safety within 24 hours of the investigator’s awareness, using the 
CT SAE Report Form.  An exposure during breastfeeding report is not created when a Pfizer 
drug specifically approved for use in breastfeeding women (eg, vitamins) is administered in 
accord with authorized use.  However, if the infant experiences an SAE associated with such 
a drug’s administration, the SAE is reported together with the exposure during breastfeeding.
8.3.5.3. Occupational Exposure 
An occupational exposure occurs when, during the performance of job duties, a person 
(whether a healthcare professional or otherwise) gets in unplanned direct contact with the 
product, which may or may not lead to the occurrence of an AE.
An occupational exposure is reported to Pfizer Safety within 24 hours of the investigator’s 
awareness, using the CT SAE Report Form, regardless of whether there is an associated 
SAE.  Since the information does not pertain to a participant enrolled in the study, the 
information is not recorded on a CRF; however, a copy of the completed CT SAE Report 
Form is maintained in the investigator site file
8.3.6. Disease-Related Events and/or Disease-Related Outcomes Not Qualifying as AEs 
or SAEs
The disease related events (DREs) for this study include episodes of bleeding related to 
hemophilia B. The bleeding episode itself is not reported as an AE, unless the bleeding 
episode meets the criteria outlined below.
Consideration on whether the bleeding event is a DRE is based on investigator determination 
and bleeding events recorded by the participant in their electronic diary will be reviewed by 
the investigator and assessed against reporting obligations for S/AE.
Bleeding, not due to the participant's hemophilia, will be recorded as an AE, and not a DRE.
If any of the following conditions apply, then the event must be recorded and reported as an
AE or SAE (instead of a DRE):
• Bleeding events that require hospitalization or meet other SAE criteria (Section 10.3) 
should be reported as SAEs. When bleeding episodes that meet the SAE criteria are recorded 
on the AE CRF, the location (site) of the bleed and the etiologic classification as spontaneous 
or traumatic should be included.
• The bleeding event is, in the investigator's opinion, of greater intensity, frequency, or
duration than expected for the individual participant.

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OR
• The investigator considers that there is a reasonable possibility that the bleeding event was 
related to study intervention.
8.3.7. Medication Errors
Medication errors may result from the administration or consumption of the investigational 
product by the wrong participant, or at the wrong time, or at the wrong dosage strength.
Exposures to the investigational product under study may occur in clinical trial settings, such 
as medication errors.
Safety Event
Recorded on the CRF
Reported on the CT SAE Report 
Form to Pfizer Safety Within 24 
Hours of Awareness
Medication errors 
All (regardless of whether 
associated with an AE)
Only if associated with an SAE
Medication errors include:
Medication errors involving participant exposure to the investigational product;
Potential medication errors or uses outside of what is foreseen in the protocol that do or do 
not involve the participating participant.
Such medication errors occurring to a study participant are to be captured on the medication 
error page of the CRF, which is a specific version of the AE page.
In the event of a medication dosing error, Pfizer should be notified immediately.
Whether or not the medication error is accompanied by an AE, as determined by the 
investigator, the medication error is recorded on the medication error page of the CRF and, if 
applicable, any associated AE(s), serious and non-serious, are recorded on an AE page of the 
CRF.
Medication errors should be reported to Pfizer Safety within 24 hours on a CT SAE Report 
Form only when associated with an SAE.
8.4. Treatment of Overdose
An overdose is any dose more than the intended dose of investigational product given to a 
participant.   Overdoses are not considered AEs; however, all overdoses should be recorded 
on an SAE form and faxed to Pfizer Safety within 24 hours.  An overdose should be reported 
even if it does not result in an AE.  Overdoses do not need to be recorded as AEs but any 
symptoms of an overdose should be reported in the eCRF as AEs; dosing information is 
recorded on an eCRF.

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For this study, any dose of PF-06838435 greater than the intended dose of 1 x 1012 vg/kg or 
2 x 1012 vg/kg of the body weight will be considered an overdose.
Sponsor does not recommend specific treatment for an overdose.
In the event of an overdose, the investigator/treating physician should:
•
Contact the Medical Monitor immediately.
•
Closely monitor the participant for any AE/SAE and laboratory abnormalities.
•
Document the quantity of the excess dose as well as the duration of the overdose in 
the CRF.
•
Overdose is reportable to Safety only when associated with a SAE.
8.5. Pharmacokinetics
All samples collected from participants for plasma factor IX activity levels will be analyzed 
at a certified clinical laboratory by one-stage assay.  Results will be used to determine peak, 
and steady-state vector-derived circulating FIX activity levels.
 
 
 
 
 
 
 
 
 
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9. STATISTICAL CONSIDERATIONS
The details of statistical methodology are specified in the Statistical Analysis Plan (SAP). In 
general, statistical analyses will be primarily descriptive in nature.  Summary statistics will 
be presented for all safety, PK and efficacy endpoints (including vector-derived FIX:C 
activity levels over time after PF-06838435 administration, annualized bleeding rate, etc.). 
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No formal statistical hypothesis testing will be performed. Various exploratory statistical 
tests may be applied to data generated from this study to generate hypotheses to be tested in 
subsequent trials.
9.1. Estimands and Statistical Hypotheses
9.1.1. Estimands
As the primary study objective is the assessment of safety and tolerability of a single IV
infusion of PF-06838435; the estimands are defined here only for the secondary objective of 
the study. This study aims to characterize kinetics of PF-06838435 after a single dose 
administration in the population of participants meeting study’s inclusion/exclusion criteria. 
The vector-derived endogenous (not affected by intercurrent FIX product infusions) FIX:C 
activity levels will be characterized by post-treatment population mean. The assessment will 
be done for each dose of PF-06838435. Since only a single IV infusion of PF-06838435 will 
be administered during the study, there should be no treatment discontinuations. There may 
be missing data, including those from participants lost to follow-up, but it is anticipated to be 
rare. The handling of missing data is discussed in SAP.
9.1.2. Statistical Hypotheses
No formal hypotheses will be tested in this study.
9.2. Sample Size Determination
No formal hypotheses will be tested in this study. The sample size is based on the need to 
establish the initial safety and kinetic profile of PF-06838435 and select dose for the proper 
efficacy assessment. Approximately 20 participants will be dosed in the study.
9.3. Populations for Analyses
For purposes of analysis, the following populations are defined:
Population
Description
Enrolled 
All participants who sign the ICF.
Dosed
All participants who were enrolled and received a single intravenous infusion 
of PF-06838435.
Evaluable
All dosed participants.
Safety
All dosed participants.
Defined sets for analysis
Description
Safety Analysis Set
All dosed participants.
Pharmacokinetics Analysis Set
All dosed participants who have collected vector-derived factor IX in 
circulation (FIX:C) activity levels enabling acceptable determination of the 
peak and steady-state derived activity level.
 
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Defined sets for analysis
Description
FIX Incremental Recovery 
Analysis Set
All dosed participants who have received 100 IU/kg of FIX protein product
infusion and have completed the blood sample collection 30 (±2) min post 
infusion for FIX protein product enabling determination of FIX incremental 
recovery.
9.4. Statistical Analysis
The statistical analysis plan will be developed and finalized before database lock and will 
describe the participant populations to be included in the analyses, and procedures for 
accounting for missing, unused, and spurious data. This section is a summary of the planned 
statistical analyses of the primary and secondary endpoints.
9.4.1. Efficacy Analyses
Endpoint
Statistical Analysis Methods
Primary
No primary efficacy endpoints.
Secondary
•
Vector-derived steady state FIX activity level will be analyzed in PK analysis set by 
dose level.
•
Vector-derived peak FIX activity level will be analyzed in PK analysis set by dose level.
•
FIX antigen levels will be analyzed in PK analysis set by dose level.
 
 
 
 
 
 
 
9.4.2. Safety Analyses
All safety analyses will be performed on the Safety Population.
Endpoint
Statistical Analysis Methods
Primary
Descriptive analyses of drug-related adverse events, laboratory abnormalities, immune 
response to AAV capsid protein, etc. will be conducted.
Secondary
No secondary safety endpoints.
 
9.4.3. Other Analyses
Other analyses will be described in the statistical analysis plan finalized before database lock.
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9.5. Interim Analyses
No formal interim analyses are planned.
9.5.1. Data Monitoring Committee (DMC)
This study will use a data monitoring committee (DMC).  The DMC is independent of the 
study team and includes external members. The DMC charter describes the role of the DMC 
in more detail.  

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10. SUPPORTING DOCUMENTATION AND OPERATIONAL CONSIDERATIONS
10.1. Appendix 1: Regulatory, Ethical, and Study Oversight Considerations
10.1.1. Regulatory and Ethical Considerations

This study will be conducted in accordance with the protocol and with the 
following:

Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical 
Sciences (CIOMS) International Ethical Guidelines

Applicable International Council for Harmonization (ICH) Good Clinical Practice 
(GCP) Guidelines

Applicable laws and regulations, including applicable privacy laws.

The protocol, protocol amendments, ICF, Investigator Brochure, and other relevant
documents (eg, advertisements) must be reviewed and approved by the sponsor and 
submitted to an IRB/IEC by the investigator and reviewed and approved by the 
IRB/IEC before the study is initiated.

Any amendments to the protocol will require IRB/IEC approval before 
implementation of changes made to the study design, except for changes necessary 
to eliminate an immediate hazard to study participants.

The investigator will be responsible for the following:

Providing written summaries of the status of the study to the IRB/IEC annually or 
more frequently in accordance with the requirements, policies, and procedures 
established by the IRB/IEC

Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures

Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR (Code of Federal Regulations), ICH guidelines, the 
IRB/IEC, European regulation 536/2014 for clinical studies (if applicable), and all 
other applicable local regulations

In the event of any prohibition or restriction imposed (ie, clinical hold) by an 
applicable regulatory authority in any area of the world, or if the investigator is 
aware of any new information that might influence the evaluation of the benefits 
and risks of the investigational product, Pfizer should be informed immediately.

In addition, the investigator will inform Pfizer immediately of any urgent safety 
measures taken by the investigator to protect the study participants against any 
immediate hazard, and of any serious breaches of this protocol or of ICH GCP that 
the investigator becomes aware of.

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10.1.2. Financial Disclosure
Investigators and sub-investigators will provide Pfizer with sufficient, accurate financial 
information as requested to allow Pfizer to submit complete and accurate financial 
certification or disclosure statements to the appropriate regulatory authorities. Investigators 
are responsible for providing information on financial interests during the course of the study 
and for 1 year after completion of the study.
10.1.3. Informed Consent Process

The investigator or his/her representative will explain the nature of the study to the 
participant or his/her legally authorized representative and answer all questions 
regarding the study.

Participants must be informed that their participation is voluntary. Participants or 
their legally authorized representative will be required to sign a statement of 
informed consent that meets the requirements of 21 CFR 50, local regulations, ICH 
guidelines, Health Insurance Portability and Accountability Act (HIPAA) 
requirements, where applicable, and the IRB/IEC or study center.

The investigator must ensure that each study participant or his or her legally 
authorized representative is fully informed about the nature and objectives of the 
study, the sharing of data related to the study and possible risks associated with 
participation, including the risks associated with the processing of the participant’s 
personal data. The participant must be informed that his/her personal study-related 
data will be used by Pfizer in accordance with local data protection law. The level of 
disclosure must also be explained to the participant.

The participant must be informed that his/her medical records may be examined by 
Clinical Quality Assurance auditors or other authorized personnel appointed by the 
sponsor, by appropriate IRB/IEC members, and by inspectors from regulatory 
authorities.

The investigator further must ensure that each study participant or his or her legally 
authorized representative is fully informed about his or her right to access and 
correct his or her personal data and to withdraw consent for the processing of his or 
her personal data.

The medical record must include a statement that written informed consent was 
obtained before the participant was enrolled in the study and the date the written 
consent was obtained. The authorized person obtaining the informed consent must 
also sign the ICF.

Participants must be re-consented to the most current version of the ICF(s) during 
their participation in the study.

A copy of the ICF(s) must be provided to the participant or the participant’s legally 
authorized representative.

Participants who are rescreened are required to sign a new ICF.

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The ICF will contain a separate section that addresses the use of remaining mandatory 
samples for optional exploratory research. The investigator or authorized designee will 
explain to each participant the objectives of the exploratory research. Participants will be 
told that they are free to refuse to participate and may withdraw their consent at any time 
and for any reason during the storage period. A separate signature will be required to 
document a participant's agreement to allow any remaining specimens to be used for 
exploratory research. Participants who decline to participate in this optional research will 
not provide this separate signature.
10.1.4. Data Protection

All parties will comply with all applicable laws, including laws regarding the 
implementation of organizational and technical measures to ensure protection of 
participant data.

Participants’ personal data will be stored at the study site in encrypted electronic 
and/or paper form and will be password protected or secured in a locked room to 
ensure that only authorized study staff have access.  The study site will implement 
appropriate technical and organizational measures to ensure that the personal data can 
be recovered in the event of disaster.  In the event of a potential personal data breach, 
the study site shall be responsible for determining whether a personal data breach has 
in fact occurred and, if so, providing breach notifications as required by law.

To protect the rights and freedoms of natural persons with regard to the processing of 
personal data, participants will be assigned a single, participant-specific numerical 
code. Any participant records or datasets that are transferred to the sponsor will 
contain the numerical code; participant names will not be transferred. All other 
identifiable data transferred to the sponsor will be identified by this single, 
participant-specific code. The study site will maintain a confidential list of 
participants who participated in the study, linking each participant’s numerical code 
to his or her actual identity. In case of data transfer, the sponsor will protect the 
confidentiality of participants’ personal data consistent with the Clinical Study 
Agreement and applicable privacy laws.
Prior to any testing under this protocol, including screening tests and assessments, candidates 
must also provide all authorizations required by local law (eg, Protected Health Information 
Authorization in North America).
The participant will not be identified by name in the eCRF or in any study reports and these 
reports will be used for research purposes only.  Pfizer, its partner(s) and designee(s), and 
various government health agencies may inspect the records of this study.  Every effort will 
be made to keep the participant’s personal medical data confidential.

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10.1.5. Committees Structure
10.1.5.1. Independent Data Monitoring Committee
The independent DMC is composed of independent experts in hemophilia or immunology.  
The independent DMC will be responsible for reviewing the safety data and other data (as 
needed) on a regular basis during the course of the study.  The specifics regarding the DMC 
organization and procedures will be outlined in the DMC Charter.
10.1.5.2. Ethics Committee Notification of Study Completion or Termination
Where required, the Health Regulatory Authorities and ethics committees must be notified of 
completion or termination of this study and sent a copy of the study synopsis in accordance 
with necessary timelines.
10.1.6. Dissemination of Clinical Study Data
Pfizer fulfills its commitment to publicly disclose clinical study results through posting the 
results of studies on www.clinicaltrials.gov (ClinicalTrials.gov), the European Clinical Trials 
Database (EudraCT), and/or www.pfizer.com, and other public registries in accordance with 
applicable local laws/regulations.  In addition, Pfizer reports study results outside of the 
requirements of local laws/regulations pursuant to its standard operating procedures (SOPs).
In all cases, study results are reported by Pfizer in an objective, accurate, balanced, and 
complete manner and are reported regardless of the outcome of the study or the country in 
which the study was conducted.
www.clinicaltrials.gov
Pfizer posts clinical trial US Basic Results on www.clinicaltrials.gov for Pfizer sponsored 
interventional studies (conducted in patients) that evaluate the safety and/or efficacy of a 
product, regardless of the geographical location in which the study is conducted.  US Basic 
Results are generally submitted for posting within 1 year of the primary completion date 
(PCD) for studies in adult populations or within 6 months of the PCD for studies in pediatric 
populations.
PCD is defined as the date that the final participant was examined or received an intervention 
for the purposes of final collection of data for the primary outcome, whether the clinical 
study concluded according to the prespecified protocol or was terminated.
EudraCT
Pfizer posts European Union (EU) Basic Results on EudraCT for all Pfizer sponsored 
interventional studies that are in scope of EU requirements.  EU Basic Results are submitted 
for posting within 1 year of the PCD for studies in adult populations or within 6 months of 
the PCD for studies in pediatric populations.

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www.pfizer.com
Pfizer posts public disclosure synopses (clinical study report [CSR] synopses in which any 
data that could be used to identify individual participants have been removed) on 
www.pfizer.com for Pfizer sponsored interventional studies at the same time the US Basic 
Results document is posted to www.clinicaltrials.gov.
Documents within marketing authorization packages/submissions
Pfizer complies with the European Union Policy 0070, the proactive publication of clinical 
data to the European Medicines Agency (EMA) website.  Clinical data, under Phase 1 of this 
policy, includes clinical overviews, clinical summaries, CSRs, and appendices containing the 
protocol and protocol amendments, sample CRFs, and statistical methods.  Clinical data, 
under Phase 2 of this policy, includes the publishing of individual participant data.  Policy 
0070 applies to new marketing authorization applications submitted via the centralized 
procedure since 01 January 2015 and applications for line extensions and for new indications 
submitted via the centralized procedure since 01 July 2015.
Data Sharing
Pfizer provides researchers secure access to patient level data or full CSRs for the purposes 
of “bona fide scientific research” that contribute to the scientific understanding of the disease, 
target, or compound class.  Pfizer will make available data from these trials 24 months after 
study completion.  Patient level data will be anonymized in accordance with applicable 
privacy laws and regulations.  CSRs will have personally identifiable information redacted.
Data requests are considered from qualified researchers with the appropriate competencies to 
perform the proposed analyses.  Research teams must include a biostatistician.  Data will not 
be provided to applicants with significant conflicts of interest, including individuals 
requesting access for commercial/competitive or legal purposes.
10.1.7. Data Quality Assurance

All participant data relating to the study will be recorded on printed or electronic 
CRF unless transmitted to the sponsor or designee electronically (eg, laboratory 
data). The investigator is responsible for verifying that data entries are accurate and 
correct by physically or electronically signing the CRF.

The investigator must maintain accurate documentation (source data) that supports 
the information entered in the CRF.

The investigator must ensure that the CRFs are securely stored at the study site in
encrypted electronic and/or paper form and are password protected or secured in a 
locked room to prevent access by unauthorized third parties.

The investigator must permit study-related monitoring, audits, IRB/IEC review, and 
regulatory agency inspections and provide direct access to source data documents. 
This verification may also occur after study completion. It is important that the 

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investigator(s) and their relevant personnel are available during the monitoring visits 
and possible audits or inspections and that sufficient time is devoted to the process.

Monitoring details describing strategy (eg, risk-based initiatives in operations and 
quality such as Risk Management and Mitigation Strategies and Analytical Risk-
Based Monitoring), methods, responsibilities and requirements, including handling 
of noncompliance issues and monitoring techniques (central, remote, or on-site 
monitoring) are provided in the Study Monitoring Plan.

The sponsor or designee is responsible for the data management of this study 
including quality checking of the data.

Study monitors will perform ongoing source data verification to confirm that data 
entered into the CRF by authorized site personnel are accurate, complete, and 
verifiable from source documents; that the safety and rights of participants are being 
protected; and that the study is being conducted in accordance with the currently 
approved protocol and any other study agreements, ICH GCP, and all applicable 
regulatory requirements.

Records and documents, including signed ICFs, pertaining to the conduct of this 
study must be retained by the investigator for a minimum of 15 years after study 
completion unless local regulations or institutional policies require a longer period. 
No records may be destroyed during the retention period without the written 
approval of the sponsor. No records may be transferred to another location or party 
without written notification to the sponsor. The investigator must ensure that the 
records continue to be stored securely for so long as they are maintained.

When participant data are to be deleted, the investigator will ensure that all copies 
of such data are promptly and irrevocably deleted from all systems.

The investigator(s) will notify sponsor or its agents immediately of any regulatory 
inspection notification in relation to the study.  Furthermore, the investigator will 
cooperate with sponsor or its agents to prepare the investigator site for the 
inspection and will allow sponsor or its agent, whenever feasible, to be present 
during the inspection.  The investigator site and investigator will promptly resolve 
any discrepancies that are identified between the study data and the participant's 
medical records.  The investigator will promptly provide copies of the inspection 
findings to sponsor or its agent.  Before response submission to the regulatory 
authorities, the investigator will provide sponsor or its agents with an opportunity to 
review and comment on responses to any such findings.
10.1.8. Source Documents

Source documents provide evidence for the existence of the participant and 
substantiate the integrity of the data collected. Source documents are filed at the 
investigator’s site.

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
Data reported on the CRF or entered in the eCRF that are transcribed from source 
documents must be consistent with the source documents or the discrepancies must 
be explained. The investigator may need to request previous medical records or 
transfer records, depending on the study. Also, current medical records must be 
available.

Definition of what constitutes source data can be found in the Study Monitoring 
Plan.
10.1.9. Study and Site Closure
The sponsor designee reserves the right to close the study site or terminate the study at any 
time for any reason at the sole discretion of the sponsor. Study sites will be closed upon study 
completion. A study site is considered closed when all required documents and study 
supplies have been collected and a study-site closure visit has been performed.
The investigator may initiate study-site closure at any time upon notification to Contract 
Research Organization (CRO) if requested to do so by the responsible IRB/IEC or if such 
termination is required to protect the health of Study Participants.
Reasons for the early closure of a study site by Pfizer may include but are not limited to:

Failure of the investigator to comply with the protocol, the requirements of the 
IRB/IEC or local health authorities, the sponsor's procedures, or GCP guidelines

Inadequate recruitment of participants by the investigator

Discontinuation of further study intervention development
Study termination is also provided for in the clinical study agreement.  If there is any conflict 
between the contract and this protocol the contract will control as to termination rights.
10.1.10. Publication Policy

The results of this study may be published or presented at scientific meetings by the 
Investigator after publication of the overall study results or one year after end of the 
study (or study termination), whichever comes first. 

The investigator agrees to refer to the primary publication in any subsequent 
publications such as secondary manuscripts, and submit all manuscripts or abstracts 
to the sponsor 30 days before submission. This allows the sponsor to protect 
proprietary information and to provide comments and the Investigator will, on 
request, remove any previously undisclosed confidential information before 
disclosure, except for any study- or Pfizer intervention-related information 
necessary to the appropriate scientific presentation or understanding of the study 
results.

For all publications relating to the study, the Investigator will comply with 
recognized ethical standards concerning publications and authorship, including 
those established by the International Committee of Medical Journal Editors.

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
The sponsor will comply with the requirements for publication of the overall study 
results covering all Investigator sites. In accordance with standard editorial and 
ethical practice, the sponsor will support publication of multicenter studies only in 
their entirety and not as individual site data. In this case, a coordinating investigator 
will be designated by mutual agreement.

Authorship of publications for the overall study results will be determined by 
mutual agreement and in line with International Committee of Medical Journal 
Editors authorship requirements.

If publication is addressed in the clinical study agreement, the publication policy set 
out in this section will not apply.
10.1.11. Sponsor’s Qualified Medical Personnel
The contact information for the sponsor's appropriately qualified medical personnel for the 
study is documented in the study contact list located in the investigator site file (ISF).
To facilitate access to appropriately qualified medical personnel on study-related medical 
questions or problems, participants are provided with a contact card.  The contact card 
contains, at a minimum, protocol and investigational product identifiers, participant study 
numbers, contact information for the investigator site, and contact details for a contact center 
in the event that the investigator site staff cannot be reached to provide advice on a medical 
question or problem originating from another healthcare professional not involved in the 
participant’s participation in the study.  The contact number can also be used by investigator 
staff if they are seeking advice on medical questions or problems; however, it should be used 
only in the event that the established communication pathways between the investigator site 
and the study team are not available.  It is therefore intended to augment, but not replace, the 
established communication pathways between the investigator site and the study team for 
advice on medical questions or problems that may arise during the study.  For sites other than 
a Pfizer CRU, the contact number is not intended for use by the participant directly, and if a 
participant calls that number, he or she will be directed back to the investigator site.

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10.2. Appendix 2: Clinical Laboratory Tests
•
The tests detailed in Table 3 will be performed by the central laboratory (CL) and/or 
by the local laboratory (LL).
•
Local laboratory results are only required in the event that the central laboratory 
results are not available in time for either study intervention administration and/or 
response evaluation. If a local sample is required, it is important that the sample for 
central analysis is obtained at the same time. Additionally, if the local laboratory 
results are used to make either a study intervention decision or response evaluation, 
the results must be entered into the CRF.
•
Protocol-specific requirements for inclusion or exclusion of participants are detailed 
in Section 5 of the protocol.
•
Additional tests may be performed at any time during the study as determined 
necessary by the investigator or required by local regulations.
Table 3.
Protocol-Required Laboratory Assessments
Assessment
Description
Hematology (CL)
•
WBC count with Differential:
o
Neutrophils
o
Lymphocytes
o
Monocytes
o
Eosinophils
o
Basophils
•
RBC count
•
Hemoglobin
•
Hematocrit
•
Platelet count
Clinical Chemistry (CL)
•
Sodium
•
Potassium
•
Chloride
•
Bicarbonate
•
Glucose
•
Phosphate
•
Serum creatinine
•
BUN
Lipid Panel (CL)
•
LDL
•
VLDL
•
HDL
•
Triglycerides
•
Total Cholesterol
ABO (LL)
•
ABO group
Urinalysis (CL)
•
pH
•
Specific Gravity
•
Protein
•
Blood 
•
Ketones
•
Glucose
Liver Function Tests (LL and 
CL)
•
Albumin, 
•
Total bilirubin
•
Direct bilirubin
•
Indirect bilirubin
•
ALP
•
AST
•
ALT 
•
Total protein
•
GGT
•
LDH
Liver Fibrosis (CL)
•
FibroTest/Fibrosure (if 
applicable)
Coagulation 
(LL, CL as noted)
•
FIX activity, aPTT (LL and CL)
•
FIX antigen, INR, TAT, 
(CL)
•
ROTEM and/or TEG (LL where available)
•
FIX inhibitor (Nijmegen Bethesda), 
(LL screening visit only, CL screening and all other visits)
AAV Neutralizing Antibody 
(CL)
•
PF-06838435 Neutralizing Antibody
Immunology (CL)
•
ELISPOT IFN-γ with PBMCs to assess cellular immune responses to 
AAV capsid and to FIX
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Table 3.
Protocol-Required Laboratory Assessments
Assessment
Description

Urine

Semen
Hepatitis B and
Hepatitis C
(CL)

Hepatitis B Surface 
Antigen

Total Hepatitis B Core 
Antibodies

HBV DNA

Hepatitis C Virus Antibodies

HCV RNA
α-Fetoprotein (CL)
Pre-existing liver disease
HIV Serology (CL)
HIV-1/HIV-2 Antibody Screen
HIV Viral load and CD4 (CL)
HIV-1 Qualitative, RNA
Spare Plasma (CL)
Aliquoted from already collected blood samples
PAXgene (CL)
RNA extraction and transcriptomic assays
Day 1 Banked Biospecimen
(CL)
Pharmacogenomics
AAV = adeno-associated virus vector; ALP = alkaline phosphatase; ALT = alanine aminotransferase; aPTT = ; 
AST = aspartate transaminase; BUN = blood urea nitrogen; CL = Central laboratory; ELISPOT = enzyme-
linked immunospot assay; FIX = coagulation factor IX; GGT = gamma-glutamyl transferase; HBV DNA = 
hepatitis B deoxyribonucleic acid; HCV RNA = hepatitis C virus ribonucleic acid; HDL = high density 
lipoprotein; HIV = human immunodeficiency virus; IFN-γ = interferon gamma; INR = international normalized 
ratio; LDH = lactate dehydrogenase; LDL = Low-density lipoprotein; LL = Local laboratory; PBMC = 
peripheral blood mononuclear cells; RBC = red blood cells; ROTEM = rotational thromboelastogram; TAT 
= thrombin-antithrombin; TEG = thromboelastography; TGA = thrombin generation assay; VLDL = very-low-
density lipoprotein; WBC = white blood cells
Investigators must document their review of each laboratory safety report.
10.3. Appendix 3: Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting
10.3.1. Definition of AE
AE Definition

An AE is any untoward medical occurrence in a patient or clinical study participant, 
temporally associated with the use of study intervention, whether or not considered 
related to the study intervention.

NOTE: An AE can therefore be any unfavorable and unintended sign (including an 
abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally 
associated with the use of study intervention.
Events Meeting the AE Definition

Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or 
other safety assessments (eg, ECG, radiological scans, vital signs measurements), 

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including those that worsen from baseline, considered clinically significant in the 
medical and scientific judgment of the investigator (ie, not related to progression of 
underlying disease).

Exacerbation of a chronic or intermittent pre-existing condition including either an 
increase in frequency and/or intensity of the condition.

New conditions detected or diagnosed after study intervention administration even 
though it may have been present before the start of the study.

Signs, symptoms, or the clinical sequelae of a suspected drug-drug interaction.

Signs, symptoms, or the clinical sequelae of a suspected overdose of either study 
intervention or a concomitant medication. Overdose per se will not be reported as an 
AE/SAE unless it is an intentional overdose taken with possible suicidal/self-harming 
intent. Such overdoses should be reported regardless of sequelae.

“Lack of efficacy” or “failure of expected pharmacological action” per se will not be 
reported as an AE or SAE. Such instances will be captured in the efficacy 
assessments. However, the signs, symptoms, and/or clinical sequelae resulting from 
lack of efficacy will be reported as AE or SAE if they fulfil the definition of an AE or 
SAE.

The signs, symptoms, and/or clinical sequelae resulting from lack of efficacy will be 
reported as AE or SAE if they fulfil the definition of an AE or SAE. Also, “lack of 
efficacy” or “failure of expected pharmacological action” also constitutes an AE or 
SAE.

“Lack of efficacy” or “failure of expected pharmacological action” per se will not be 
reported as an AE or SAE. Such instances will be captured in the efficacy 
assessments. However, the signs, symptoms, and/or clinical sequelae resulting from 
lack of efficacy will be reported as AE or SAE if they fulfil the definition of an AE or 
SAE.
Events NOT Meeting the AE Definition

Any clinically significant abnormal laboratory findings or other abnormal safety 
assessments which are associated with the underlying disease, unless judged by the 
investigator to be more severe than expected for the participant’s condition.

The disease/disorder being studied or expected progression, signs, or symptoms of the 
disease/disorder being studied, unless more severe than expected for the participant’s 
condition.

Medical or surgical procedure (eg, endoscopy, appendectomy): the condition that 
leads to the procedure is the AE.

Situations in which an untoward medical occurrence did not occur (social and/or 
convenience admission to a hospital).

Anticipated day-to-day fluctuations of pre-existing disease(s) or condition(s) present 

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or detected at the start of the study that do not worsen.
10.3.2. Definition of SAE
If an event is not an AE per definition above, then it cannot be an SAE even if serious 
conditions are met (eg, hospitalization for signs/symptoms of the disease under study, death 
due to progression of disease).
A SAE is defined as any untoward medical occurrence that, at any dose:
a.
Results in death
b.
Is life-threatening
The term 'life-threatening' in the definition of 'serious' refers to an event in which the 
participant was at risk of death at the time of the event. It does not refer to an event, which 
hypothetically might have caused death, if it were more severe.
c.
Requires inpatient hospitalization or prolongation of existing hospitalization
In general, hospitalization signifies that the participant has been detained (usually involving 
at least an overnight stay) at the hospital or emergency ward for observation and/or treatment 
that would not have been appropriate in the physician’s office or outpatient setting. 
Complications that occur during hospitalization are AEs. If a complication prolongs 
hospitalization or fulfills any other serious criteria, the event is serious. When in doubt as to 
whether “hospitalization” occurred or was necessary, the AE should be considered serious.
Hospitalization for elective treatment of a pre-existing condition that did not worsen from 
baseline is not considered an AE.
d.
Results in persistent disability/incapacity

The term disability means a substantial disruption of a person’s ability to conduct 
normal life functions.

This definition is not intended to include experiences of relatively minor medical 
significance such as uncomplicated headache, nausea, vomiting, diarrhea, influenza, 
and accidental trauma (eg, sprained ankle) which may interfere with or prevent 
everyday life functions but do not constitute a substantial disruption.
e.
Is a congenital anomaly/birth defect
f.
Other situations:

Medical or scientific judgment should be exercised in deciding whether SAE 
reporting is appropriate in other situations such as important medical events that may 
not be immediately life-threatening or result in death or hospitalization but may 
jeopardize the participant or may require medical or surgical intervention to prevent 
one of the other outcomes listed in the above definition. These events should usually 
be considered serious.
Examples of such events include invasive or malignant cancers, intensive treatment in an 
emergency room or at home for allergic bronchospasm, blood dyscrasias or convulsions 
that do not result in hospitalization, or development of drug dependency or drug abuse.
In this study, the following events are considered medically important and must be reported 
as SAEs:

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
Any drug-related death during the study;

Any subject develops drug-related or possibly drug-related Grade III-IV 
toxicity such as FIX inhibitor, allergic reaction (bronchospasm and 
anaphylaxis), excluding elevated transaminases (Section 10.8);

Any subject develops drug-related or possibly drug-related Grade III-IV 
elevated hepatic transaminases that fails to improve or resolve within four 
weeks on the immunosuppressive regimens (Section 10.8);

Any subject develops drug-related or possibly drug-related Grade IV 
(>10-fold) elevated transaminases (Section 10.8);

Any subject reaches >150% of normal vector-derived FIX:C activity levels 
and develops drug-related or possibly drug-related thrombotic event (with the 
exception of IV infusion-site thrombophlebitis) or if any subject develops a 
sustained (defined as > 6 weeks) FIX activity levels of > 150%;

Any occurrence of a malignancy at any point after vector infusion that is 
possibly, probably, or definitely related to the investigational product.
Participants will be informed of early symptoms and signs of thrombotic phenomena, 
including pain and/or tenderness along a vein, swelling of an arm or leg without pain or 
tenderness, redness along a vein, low fever without any known reason (such as a cold or flu), 
sudden shortness of breath or difficulty breathing or coughing, sudden chest pain, sudden 
severe headache or changes in vision, and numbness or tingling in arms or legs.  If such an 
event occurs while the subject is at home, the subject will be instructed to seek immediate 
medical care.
10.3.3. Recording and Follow-Up of AE and/or SAE
AE and SAE Recording/Reporting
The table below summarizes the requirements for recording adverse events on the CRF and 
for reporting SAEs on the Clinical Trial (CT) Serious Adverse Event (SAE) Report Form to 
Pfizer Safety.  These requirements are delineated for 3 types of events: (1) SAEs; (2) non-
serious adverse events (AEs); and (3) exposure to the investigational product under study 
during pregnancy or breastfeeding, and occupational exposure.  
It should be noted that the CT SAE Report Form for reporting of SAE information is not the 
same as the AE page of the CRF.  When the same data are collected, the forms must be 
completed in a consistent manner.  AEs should be recorded using concise medical 
terminology and the same AE term should be used on both the CRF and the CT SAE Report 
Form for reporting of SAE information

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Safety Event
Recorded on the CRF
Reported on the CT SAE 
Report Form to Pfizer 
Safety Within 24 Hours of 
Awareness
SAE
All
All
Non-serious AE
All
None
Exposure to the 
investigational product 
under study during 
pregnancy or 
breastfeeding and 
occupational exposure
None
All (And exposure during 
pregnancy [EDP] 
supplemental form for EDP)  

When an AE/SAE occurs, it is the responsibility of the investigator to review all 
documentation (eg, hospital progress notes, laboratory reports, and diagnostics 
reports) related to the event.

The investigator will then record all relevant AE/SAE information in the CRF.

It is not acceptable for the investigator to send photocopies of the participant’s 
medical records to Pfizer safety in lieu of completion of the CT SAE Report 
Form/AE/SAE CRF page.

There may be instances when copies of medical records for certain cases are 
requested by Pfizer Safety. In this case, all participant identifiers, with the exception 
of the participant number, will be redacted on the copies of the medical records 
before submission to Pfizer Safety.

The investigator will attempt to establish a diagnosis of the event based on signs, 
symptoms, and/or other clinical information. Whenever possible, the diagnosis (not 
the individual signs/symptoms) will be documented as the AE/SAE.
Assessment of Intensity
The investigator will make an assessment of intensity for each AE and SAE reported during 
the study and assign it to 1 of the following categories:

Mild: An event that is easily tolerated by the participant, causing minimal discomfort 
and not interfering with everyday activities.

Moderate: An event that causes sufficient discomfort and interferes with normal 
everyday activities.

Severe: An event that prevents normal everyday activities. An AE that is assessed as 
severe should not be confused with a SAE. Severe is a category utilized for rating the 
intensity of an event; and both AEs and SAEs can be assessed as severe.

Life-threatening: Occurrence of the event places the subject at immediate risk of 
death.

Death: Occurrence of the event results in the death of the subject. 
An event is defined as ‘serious’ when it meets at least 1 of the predefined outcomes as 

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described in the definition of an SAE, NOT when it is rated as severe.
If applicable, the toxicity grade in Appendix 8 should also be noted.
Assessment of Causality

The investigator is obligated to assess the relationship between study intervention and 
each occurrence of each AE/SAE.

A “reasonable possibility” of a relationship conveys that there are facts, evidence, 
and/or arguments to suggest a causal relationship, rather than a relationship cannot be 
ruled out.

The investigator will use clinical judgment to determine the relationship.

Alternative causes, such as underlying disease(s), concomitant therapy, and other risk 
factors, as well as the temporal relationship of the event to study intervention 
administration will be considered and investigated.

The investigator will also consult the Investigator’s Brochure (IB) and/or Product 
Information, for marketed products, in his/her assessment.

For each AE/SAE, the investigator must document in the medical notes that he/she 
has reviewed the AE/SAE and has provided an assessment of causality.

There may be situations in which an SAE has occurred and the investigator has 
minimal information to include in the initial report to Pfizer. However, it is very 
important that the investigator always makes an assessment of causality for 
every event before the initial transmission of the SAE data to Pfizer.

The investigator may change his/her opinion of causality in light of follow-up 
information and send a SAE follow-up report with the updated causality assessment.

The causality assessment is one of the criteria used when determining regulatory 
reporting requirements.

If the investigator does not know whether or not the investigational product caused 
the event, then the event will be handled as “related to investigational product” for 
reporting purposes, as defined by the sponsor" and "In addition, if the investigator 
determines that an SAE is associated with study procedures, the investigator must 
record this causal relationship in the source documents and CRF, and report such an 
assessment in the dedicated section of the CT SAE Report Form and in accordance 
with the SAE reporting requirements.
The following definitions should be considered when evaluating the relationship of AEs and 
SAEs to the investigational product:
Relationship
Description
Not related
An event that does not follow a reasonable temporal sequence from 
administration of investigational product AND that is likely to have been 
produced independently by the subject’s clinical state, environmental or 
toxic factors, or other modes of therapy administered to the subject.

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Unlikely 
Any event that does not follow a reasonable temporal sequence from 
administration of investigational product OR that is likely to have been 
produced by the subject’s clinical state, environmental or toxic factors, or 
other modes of therapy administered to the subject.
Possibly 
Any reaction that follows a reasonable temporal sequence from 
administration of investigational product OR that follows a known 
response pattern to the suspected drug AND that could not be reasonably 
explained by the known characteristics of the subject’s clinical state, toxic 
or environmental factors or other modes of therapy administered to the 
subject.
Related
Any reaction that follows a reasonable temporal sequence from 
administration of investigational product AND that follows a known 
response pattern to the suspected drug AND that recurs with re-challenge, 
AND/OR is improved by stopping the drug or reducing the dose.
Follow-up of AEs and SAEs

The investigator is obligated to perform or arrange for the conduct of supplemental 
measurements and/or evaluations as medically indicated or as requested by Pfizer to 
elucidate the nature and/or causality of the AE or SAE as fully as possible. This may 
include additional laboratory tests or investigations, histopathological examinations, 
or consultation with other health care professionals.

If a participant dies during participation in the study or during a recognized follow-up 
period, the investigator will provide Pfizer Safety with a copy of any post-mortem 
findings including histopathology.

New or updated information will be recorded in the originally completed CRF.

The investigator will submit any updated SAE data to Pfizer Safety within 24 hours 
of receipt of the information.
10.3.4. Reporting of SAEs
SAE Reporting to Pfizer Safety via an Electronic Data Collection Tool

The primary mechanism for reporting an SAE to Pfizer Safety will be the electronic 
data collection tool.

If the electronic system is unavailable, then the site will use the paper SAE data 
collection tool (see next section) in order to report the event within 24 hours.

The site will enter the SAE data into the electronic system as soon as it becomes 
available.

After the study is completed at a given site, the electronic data collection tool will be 
taken off-line to prevent the entry of new data or changes to existing data.

If a site receives a report of a new SAE from a study participant or receives updated 
data on a previously reported SAE after the electronic data collection tool has been 

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taken off-line, then the site can report this information on a paper SAE form (see next 
section) or to the Pfizer Safety by telephone.

Contacts for SAE reporting can be found in the ISF.
SAE Reporting to Pfizer Safety via Paper CRF

Facsimile transmission of the SAE paper CRF is the preferred method to transmit this 
information to the Pfizer

In rare circumstances and in the absence of facsimile equipment, notification by 
telephone is acceptable with a copy of the SAE data collection tool sent by overnight 
mail or courier service.

Initial notification via telephone does not replace the need for the investigator to 
complete and sign the SAE CRF pages within the designated reporting time frames.

Contacts for SAE reporting can be found in the ISF.

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10.4. Appendix 4: Contraceptive Guidance and Collection of Pregnancy Information
Contraception Guidance:
Contraception guidance for the male participants until at least 3 consecutive ejaculate 
samples test negative for vector shedding is as follows:

Refrain from donating sperm;
PLUS either:

Be abstinent from heterosexual or homosexual intercourse as their preferred and 
usual lifestyle (abstinent on a long term and persistent basis) and agree to remain 
abstinent;
OR

Must agree to use contraception/barrier as detailed below:

Agree to use male condom when engaging in any activity that allows for 
passage of ejaculate to another person.
Collection of Pregnancy Information:
For both unapproved/unlicensed products and for marketed products, an exposure during 
pregnancy (EDP) occurs if:

A female becomes, or is found to be, pregnant either while receiving or having been 
exposed (eg, because of treatment or environmental exposure) to the investigational 
product; or the female becomes or is found to be pregnant after discontinuing and/or 
being exposed to the investigational product;

An example of environmental exposure would be a case involving direct contact 
with a Pfizer product in a pregnant woman (eg, a nurse reports that she is pregnant 
and has been exposed to chemotherapeutic products).

A male has been exposed (eg, because of treatment or environmental exposure) to the 
investigational product prior to or around the time of conception and/or is exposed 
during his partner’s pregnancy. 
If a participant or participant’s partner becomes or is found to be pregnant during the 
participant’s treatment with the investigational product, the investigator must report this 
information to Pfizer Safety on the CT SAE Report Form and an EDP supplemental form, 
regardless of whether an SAE has occurred.  In addition, the investigator must submit 
information regarding environmental exposure to a Pfizer product in a pregnant woman (eg, a 
participant reports that she is pregnant and has been exposed to a cytotoxic product by 
inhalation or spillage) to Pfizer Safety using the EDP supplemental form.  This must be done 

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irrespective of whether an AE has occurred and within 24 hours of awareness of the 
exposure.  The information submitted should include the anticipated date of delivery (see 
below for information related to termination of pregnancy).
Follow-up is conducted to obtain general information on the pregnancy and its outcome for 
all EDP reports with an unknown outcome.  The investigator will follow the pregnancy until 
completion (or until pregnancy termination) and notify Pfizer Safety of the outcome as a 
follow-up to the initial EDP supplemental form.  In the case of a live birth, the structural 
integrity of the neonate can be assessed at the time of birth.  In the event of a termination, the 
reason(s) for termination should be specified and, if clinically possible, the structural 
integrity of the terminated fetus should be assessed by gross visual inspection (unless pre-
procedure test findings are conclusive for a congenital anomaly and the findings are 
reported).
If the outcome of the pregnancy meets the criteria for an SAE (ie, ectopic pregnancy, 
spontaneous abortion, intrauterine fetal demise, neonatal death, or congenital anomaly [in a 
live-born baby, a terminated fetus, an intrauterine fetal demise, or a neonatal death]), the 
investigator should follow the procedures for reporting SAEs.
Additional information about pregnancy outcomes that are reported to Pfizer Safety as SAEs 
follows: 

Spontaneous abortion includes miscarriage and missed abortion;

Neonatal deaths that occur within 1 month of birth should be reported, without regard 
to causality, as SAEs.  In addition, infant deaths after 1 month should be reported as 
SAEs when the investigator assesses the infant death as related or possibly related to 
exposure to the investigational product.
Additional information regarding the EDP may be requested by the sponsor.  Further follow-
up of birth outcomes will be handled on a case-by-case basis (eg, follow-up on preterm 
infants to identify developmental delays). In the case of paternal exposure, the investigator 
will provide the participant with the Pregnant Partner Release of Information Form to deliver 
to his partner.  The investigator must document in the source documents that the participant 
was given the Pregnant Partner Release of Information Form to provide to his partner.

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10.5. Appendix 5: Genetics
Use/Analysis of DNA

Genetic variation may impact a participant’s response to study intervention, 
susceptibility to, and severity and progression of disease. Therefore, where local 
regulations and IRB/IEC allow, a blood sample will be collected for DNA analysis.

Genetic research may consist of the analysis of one or more candidate genes or the 
analysis of genetic markers throughout the genome or analysis of the entire genome 
(as appropriate).

The samples may be analyzed as part of a multi-study assessment of genetic factors 
involved in the response to study intervention or study interventions of this class, 
treatments for the disease(s) under study or the disease(s) themselves.

The results of genetic analyses may be reported in the clinical study report (CSR) or 
in a separate study summary, or may be used for internal decision-making without 
being included in a study report.

The sponsor will store the DNA samples in a secure storage space with adequate 
measures to protect confidentiality.

The samples will be retained as indicated:

Samples for specified genetic analysis (Section 8.7) will not be stored 
beyond the completion of this study (eg, Clinical Study Report 
finalization).

Samples for banking (see Section 8.7) will be stored indefinitely or other 
period as per local requirements.  

Participants may withdraw their consent for the storage and/or use of their Banked 
Biospecimens at any time by making a request to the investigator; in this case, any 
remaining material will be destroyed.  Data already generated from the samples will 
be retained to protect the integrity of existing analyses.   

Banked Biospecimens will be labelled with a code.  

The key between the code and the participant’s personally identifying information 
(eg, name, address) will be held at the study site and will not be provided to the 
sample bank.  

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10.6. Appendix 6: Liver Safety: Suggested Actions and Follow-up Assessments
Humans exposed to a drug who show no sign of liver injury (as determined by elevations in 
transaminases) are termed “tolerators,” while those who show transient liver injury, but adapt 
are termed “adaptors.”  In some participants, transaminase elevations are a harbinger of a 
more serious potential outcome.  These participants fail to adapt and therefore are 
"susceptible" to progressive and serious liver injury, commonly referred to as drug-induced 
liver injury (DILI).  Participants who experience a transaminase elevation above 3 times the 
ULN should be monitored more frequently to determine if they are an “adaptor” or are 
“susceptible.”
In the majority of DILI cases, elevations in aspartate aminotransferase (AST) and/or alanine 
aminotransferase (ALT) precede total bilirubin (TBili) elevations (>2 × ULN) by several 
days or weeks.  The increase in TBili typically occurs while AST/ALT is/are still elevated 
above 3 × ULN (ie, AST/ALT and TBili values will be elevated within the same lab sample).  
In rare instances, by the time TBili elevations are detected, AST/ALT values might have 
decreased.  This occurrence is still regarded as a potential DILI.  Therefore, abnormal 
elevations in either AST OR ALT in addition to TBili that meet the criteria outlined below 
are considered potential DILI (assessed per Hy’s law criteria) cases and should always be 
considered important medical events, even before all other possible causes of liver injury 
have been excluded.
The threshold of laboratory abnormalities for a potential DILI case depends on the 
participant’s individual baseline values and underlying conditions.  Participants who present 
with the following laboratory abnormalities should be evaluated further as potential DILI 
(Hy’s law) cases to definitively determine the etiology of the abnormal laboratory values:

Participants with AST/ALT and TBili baseline values within the normal range who 
subsequently present with AST OR ALT values >3 × ULN AND a TBili value 
>2 × ULN with no evidence of hemolysis and an alkaline phosphatase value 
<2 × ULN or not available;

For participants with baseline AST OR ALT OR TBili values above the ULN, the 
following threshold values are used in the definition mentioned above, as needed, 
depending on which values are above the ULN at baseline:

Preexisting AST or ALT baseline values above the normal range: AST or ALT 
values >2 times the baseline values AND >3 × ULN; or >8 × ULN (whichever is 
smaller).

Preexisting values of TBili above the normal range: TBili level increased from 
baseline value by an amount of at least 1 × ULN or if the value reaches >3 × ULN 
(whichever is smaller).
Rises in AST/ALT and TBili separated by more than a few weeks should be assessed 
individually based on clinical judgment; any case where uncertainty remains as to whether it 
represents a potential Hy’s law case should be reviewed with the sponsor.  

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The participant should return to the investigator site and be evaluated as soon as possible, 
preferably within 48 hours from awareness of the abnormal results.  This evaluation should 
include laboratory tests, detailed history, and physical assessment. 
In addition to repeating measurements of AST and ALT and TBili for suspected cases of 
Hy’s Law, additional laboratory tests should include albumin, creatine kinase (CK), direct 
and indirect bilirubin, gamma-glutamyl transferase (GGT), prothrombin time 
(PT)/international normalized ratio (INR), total bile acids, and alkaline phosphatase. 
Consideration should also be given to drawing a separate tube of clotted blood and an 
anticoagulated tube of blood for further testing, as needed, for further contemporaneous 
analyses at the time of the recognized initial abnormalities to determine etiology.  A detailed 
history, including relevant information, such as review of ethanol, acetaminophen (either by 
itself or as a coformulated product in prescription or over-the-counter medications), 
recreational drug, supplement (herbal) use and consumption, family history, sexual history, 
travel history, history of contact with a jaundiced person, surgery, blood transfusion, history 
of liver or allergic disease, and potential occupational exposure to chemicals, should be 
collected.  Further testing for acute hepatitis A, B, C, D, and E infection and liver imaging 
(eg, biliary tract) and collection of serum sample for acetaminophen drug and/or protein 
adduct levels may be warranted.
All cases demonstrated on repeat testing as meeting the laboratory criteria of AST/ALT and 
TBili elevation defined above should be considered potential DILI (Hy’s law) cases if no 
other reason for the LFT abnormalities has yet been found.  Such potential DILI (Hy’s law) 
cases are to be reported as SAEs, irrespective of availability of all the results of the 
investigations performed to determine etiology of the LFT abnormalities.  
A potential DILI (Hy’s law) case becomes a confirmed case only after all results of 
reasonable investigations have been received and have excluded an alternative etiology.
Unique to PF-06838435 is the potential for T-cell induced hepatocyte destruction. In a subset 
of participants, presentation of capsid protein by major histocompatibility complex (MHC) to 
the surface of a hepatocyte can trigger CD8 cell mediated targeting of hepatocytes. This 
presents asymptomatically with a rise in LFTs and/or a decline in FIX activity levels. This 
effect is not due to direct hepatocyte toxicity rather it is an immunologic response. This 
immunologic reaction has been shown in prior studies and the Phase 1/2a study to respond to 
intervention with corticosteroids.

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10.8. Appendix 8: Toxicity Scale
Toxicity
Grade 1
Grade 2
Grade 3
Grade 4
General
Fever
37.8–38.5°C
38.6–39.5°C
39.6–40.0°C
>40.0°C
Chills 
Mild, transient
Moderate
Severe
Intractable
Fatigue
Symptomatic, fully 
ambulatory
Symptomatic, in bed 
<50% of time
Symptomatic, in bed 
>50% of time, not 
bedridden
100% bedridden
Weight loss
2.0 – 2.9%
3.0 – 4.9%
5.0 – 10.0%
> 10.0%
Injection site
Pain, erythmea, 
surface ecchymosis; 
no extra factor 
required
Pain; erythmea, 
hematoma; factor 
required
Pain; erythmea, 
hematoma; factor 
required; prevents 
ambulation
Pain; erythmea, 
hematoma; factor 
required; prevents 
ambulation; lasting >3 
weeks
Coagulation
Factor IX inhibitor
0.5 – 4.9 B.U. 
persisting <3 months
0.5 – 4.9 B.U. 
persisting >3 months
䍹5.0 B.U. persisting 
<3 months
䍹5.0 B.U. persisting 
>3 months
Hematology
Leukocytosis
1.5 – 2.0X baseline
2.1 – 2.5X baseline
2.6 – 3.0X baseline
> 3.0X baseline
Thrombocytopenia
40,000 – 50,000/mL
30,000 – 39,999/mL
20,000 – 29,999/mL
< 20,000/mL
Anemia
8.0 – 9.9 g/dL
7.0 – 7.9 g/dL
6.0 – 6.9 g/dL
< 6.0 g/dL
Hepatic
Elevated Bilirubin
1.2 – 1.5X baseline
1.6 – 2.0X baseline
2.1 – 3.0X baseline
> 3.0X baseline
Elevated 
Transaminases
2.5 – 2.9X normal
3.0 – 4.9X normal
5.0 – 10.0X normal
> 10.0X normal
Elevated Alkaline 
Phosphatase
2.0 – 2.9X normal
3.0 – 4.9X normal
5.0 – 10.0X normal
> 10.0X normal
Renal
Elevated Creatinine 
(mg/dL)
1.1 – 1.5X normal
1.6 – 2.0X normal
2.1 – 3.0X normal
> 3.0X normal
Proteinuria
1+
2 – 3+
4+
Nephrotic syndrome
Hematuria
Micro only
Gross no clots
Gross + clots
Requires transfusion
Gastrointestinal
Appetite
Normal intake
Intake significantly 
decreased but can eat
No significant intake
Requires transfusion
Nausea/vomiting
Nausea alone
Transient vomiting
Vomiting requiring 
therapy
Intractable vomiting
Diarrhea
Transient <2 days; 
freq loose BM 
<4/day; no therapy 
required
Tolerable but > 2 
days; freq loose BM 
>4/day; relief with 
therapy
Intolerable or bloody 
diarrhea; no relief 
with therapy
Dehydration and 
hospitalization
Pulmonary
Respiratory symptoms
Mild (eg, 1 flight 
SOB)
Exertional dyspnea 
(eg, SOB while 
walking)
Dyspnea at rest
Complete bed rest; 
Continuous assisted 
O2 ventilation
Chest X-Ray
Localized increase in 
lung markings
Multi-focal increase 
in lung markings
Increase in lung 
markings with focal 
infiltrate
Mutillobar infiltrates
PFTs (FEV, FVC)
10 – 15% decline
16 – 20% decline
21 – 25% decline
> 25% decline
Skin/Allergy
Cutaneous and 
Allergy
Transient erythema
Dry desquamation, 
vesiculation, pruritis 
or phlebitis; urticaria
Moist desquamation; 
serum sickness
Exfoliative dermatitis; 
anaphylaxis
Metabolic
Hyperglycemia
120 -160 mg/dL
161 – 250 mg/dL
251 – 500 mg/dL
>500 mg/dL or 
diabetic ketoacidosis
Hypoglycemia
55 – 64 mg/dL
40 – 54 mg/dL
30 – 39 mg/dL
<30 mg/dL
Hypocalcemia
8.3 – 7.8 mg/dL
7.7 – 7.0 mg/dL
6.9 – 6.1 mg/dL
<6.0 mg/dL
Hyperkalemia
5.1 – 5.4 mg/dL
5.5 – 5.9 mg/dL
6.0 – 6.4 mg/dL
>6.4 mg/dL

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Central Nervous System
Headache
Mild, transient, no 
therapy required
Analgesic required
Narcotic required
Intractable
Mental status
Mild somnolence, 
agitation or confusion
Moderate  
somnolence, agitation 
or confusion 
Severe somnolence, 
confusion, 
disorientation, 
hallucination
Coma, seizures, toxic 
psychosis
Motor
Subjective weakness, 
no objective findings
Mild objective 
weakness without 
significant 
impairment of 
function
Objective weakness 
with impairment of 
function
Paralysis
Sensory
Mild paresthesia, loss 
of DTRs
Mild or moderate 
objective sensory loss, 
moderate paresthesia
Severe objective 
sensory loss or 
paresthesia that 
interferes with 
function
Cardiovascular
Cardiac symptoms
Asymptomatic but 
abnormal cardiac sign
Transient symptoms; 
no therapy required
Symptomatic but 
responds to therapy
Symptomatic & no 
response to therapy
Ischemia
Non-specific ST or T 
wave changes
Asymptomatic, ST 
and T wave changes 
suggesting ischemia
Angina without 
evidence of infarction
Acute myocardial 
infarction
Hypertension
Asymptomatic, 
transient increase by 
greater than 20 mm 
Hg (D) or to 
>150/100 if 
previously WNL; No 
treatment required
Recurrent or 
persistent increase by 
greater than 20 mm 
Hg (D) or to 
>150/100 if 
previously WNL.  No 
treatment required
Requires therapy
Hypertensive crisis
Hypotension
Clinically significant 
changes requiring no 
therapy (including 
transient orthostatic 
hypotension)
Requires fluid 
replacement or other 
therapy but not 
hospitalization
Requires therapy and 
hospitalization; 
resolves within 
48 hours of therapy
Requires therapy and 
hospitalization; 
requires >48 hours of 
therapy
Freq = frequent; BM = bowel movements; DTR = deep tendon reflexes; SOB = shortness of breath; 
WNL = within normal limits 

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10.9. Appendix 9: Abbreviations
AASLD
American Association for the Study of Liver 
Diseases
AAV
adeno-associated virus vector
AAV2
adeno-associated virus vector, serotype 2
AAV8
adeno-associated virus vector, serotype 8
AAV-hFIX
adeno-associated viral vector expressing 
human factor IX
AAV2-hFIX16
single-stranded adeno-associated viral vector, 
serotype 2, expressing human factor IX under 
control of the human α1-antitrypsin promoter 
coupled to the human apolipoprotein E 
hepatic locus control region
AAV8-hFIX19
single-stranded adeno-associated viral vector, 
serotype 8, expressing human factor IX under 
control of the human α1-antitrypsin promoter 
coupled to the human apolipoprotein E 
hepatic locus control region (construct 
changes from hFIX16 to hFIX19 include 
codon-optimization, removal of alternate 
open reading frames of the factor IX gene, 
and replacement of amp with kan resistance 
in the plasmid used for vector generation) 
AAV8-LP1-hFIXco
self-complementary AAV vector, serotype 8, 
expressing human factor IX, used in the St. 
Jude’s/UCL gene therapy trial
AAV-Spark100-hFIX19-Padua
adeno-associated viral vector comprised of 
the Spark100 AAV capsid encoding hFIX-
Padua
ABR
annualized bleed rate
AEs
adverse events
AIDS
acquired immunodeficiency syndrome
ALT
alanine aminotransferase
amp
ampicillin resistance gene
APRI
aPTT
AST-to-platelet ratio index
activated partial thromboplastin time
AST
aspartate transaminase
BMI
body mass index
BUN
blood urea nitrogen 
CFR
CNS
Code of Federal Regulations
central nervous system
cp
capsid particles
CPT
CRO
common protocol template
Contract Research Organization

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CSR
CT
CTL
clinical study report
clinical trial
cytotoxic T lymphocyte
CVAD
central venous access device
DNA
deoxyribonucleic acid
DMC
data monitoring committee
DILI
DRE
EAHAD
drug-induced liver injury
disease related event
European Association for Haemophilia and 
Allied Disorders
eCRF
electronic case report form
ECG
ED
EDP
electrocardiogram
exposure day
exposure during pregnancy
ELISPOT
EOS
enzyme-linked immunospot assay
end of study
EudraCT
FDA
European Clinical Trials Database
Food and Drug Administration 
FIX
factor IX
FIX:C
Circulating factor IX 
GCP
Good Clinical Practice
GGT
gamma-glutamyl transferase
Haem-A-QoL
HAL
HBV
HBsAg
haemophilia A quality of life questionnaire
hemophilia activities list
hepatitis B virus
hepatitis B surface antigen
HCV
hepatitis C virus 
hFIX
human coagulation factor IX
HIV
HJHS
human immunodeficiency virus
hemophilia joint health score
HLA
human leukocyte antigen
HRQoL
health-related quality-of-life
IB
ICF
Investigator Brochure
Informed Consent Form
ICH
International Council for Harmonisation 
ID
IEC
Identification
independent ethics committee
IFN
interferon
IFN-γ
interferon gamma
IgG4
immunoglobulin G subclass 4
IND
investigational new drug 
INR
international normalized ratio
IP
IRB
investigational product
institutional review board
ISF
investigator site file

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IU
international units 
IV
intravenous
kan
kanamycin resistance gene
LDH
lactate dehydrogenase 
LFT
liver function test
LSLV
last subject last visit
LTFU
long-term follow-up
MHC
major histocompatibility complex 
NAb
neutralizing antibody
NHP
non-human primate 
PBMC
peripheral blood mononuclear cells 
PCD
primary completion date
PCR
polymerase chain reaction
pd
plasma derived
pd-FIX
plasma-derived factor IX
PK
PO
pharmacokinetic
orally 
PT
prothrombin time 
QD
once a day
QoL
rFIX
quality of life
recombinant factor IX
RNA
ribonucleic acid
ROTEM
rotational thromboelastogram
SAE
serious adverse event 
SAP
SJ-UCL
statistical analysis plan
St. Jude Children’s Research Hospital –
University College London
SOP
standard operating procedure 
PF-06838435 
adeno-associated viral vector with FIX gene 
(AAV-Spark100-hFIX19-Padua) 
SUSAR
suspected unexpected serious adverse 
reaction
TAT
thrombin-antithrombin
TBili
TEG
total bilirubin
thromboelastography
TGA
thrombin generation assay
Tmax
Time at maximum activity
ULN
upper limit of normal 
vg
vector genome 
WBC
white blood cell
WNL
within normal limits
WT
wild-type

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