Gene-transfer, Open-label, Dose-escalation Study of SPK-8011 [Adeno-associated Viral Vector With B-domain Deleted Human Factor VIII Gene] in Individuals With Hemophilia A
Phase: PHASE1
Conditions: Hemophilia A
Sponsor: Spark Therapeutics, Inc.

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TITLE PAGE 
PROTOCOL TITLE: 
Gene-transfer, open-label, dose-escalation study of SPK-8011 
[adeno-associated viral vector with B-domain deleted human 
factor VIII gene] in individuals with hemophilia A  
PROTOCOL NUMBER: 
SPK-8011-101 
INVESTIGATIONAL 
PRODUCT/NUMBER: 
SPK-8011 
PHASE OF 
DEVELOPMENT 
1/2a 
INDICATION: 
Hemophilia A 
SPONSOR: 
Spark Therapeutics 
SPONSOR ADDRESS: 
3737 Market Street, Suite 1300 
Philadelphia, PA 19104 
REGULATORY AGENCY 
IDENTIFYING 
NUMBER(S): 
IND #17151 
ORIGINAL PROTOCOL 
DATE: 
17-Oct-2016
AMENDMENT NUMBER: 7 
VERSION DATE: 
09-Feb-2021
This study will be conducted in accordance with the standards of Good Clinical Practice (as defined by the 
International Conference on Harmonization), the ethical principles that have their origin in the Declaration of Helsinki 
and all applicable national and local regulations.  
This protocol includes information and data that contain trade secrets and privileged or confidential information, which 
is the property of Spark Therapeutics, Inc. (“Spark”).  This information must not be made public without written 
permission from Spark.  These restrictions on disclosure will apply equally to all future information supplied to you. 
This material may be disclosed to and used by your staff and associates as may be necessary to conduct the clinical 
study. 
NCT #: NCT03003533

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SPONSOR SIGNATORY FORM 
 
Protocol Title: Gene-transfer, open-label, dose-escalation study of SPK-8011 [adeno-
associated viral vector with B-domain deleted human factor VIII gene] in individuals 
with hemophilia A 
 
Protocol No: SPK-8011-101 
 
This study protocol was subject to critical review and has been approved by the appropriate protocol 
reviewers of the sponsor.  The information contained in this protocol is consistent with: 
• 
The current benefit-risk evaluation of the investigational product. 
• 
The moral, ethical, and scientific principles governing clinical research as set out in the 
Declaration of Helsinki, International Conference on Harmonization Good Clinical Practice (ICH 
GCP) guidelines and according to applicable local requirements. 
The Investigator will be supplied with details of any significant or new findings, including adverse 
events, relating to treatment with the investigational product. 
Spark Therapeutics: 
Head of Clinical Research and Development or Medical Designee that Signed the Internal 
Protocol Approval Form:  
 
 
 
Spark Therapeutics                                                                                   
 
 
 
Signature  
 
 
 
 
Date (dd-MMM-yyyy) 
 
PPD

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INVESTIGATOR STATEMENT 
I have read the protocol, including all appendices, and I agree that it contains all of the 
necessary information for me and my staff to conduct this study as described. I will conduct 
this study as outlined herein, in accordance with Good Clinical Practice: Consolidated 
Guideline approved by the International Conference on Harmonization and all applicable local 
and federal regulatory requirements and will make a reasonable effort to complete the study 
within the time designated. 
I will provide all study personnel under my supervision copies of the protocol and any 
amendments, and access to all information provided by Spark or specified designees. I will 
discuss the material with them to ensure that they are fully informed about the study. 
 
 
 
 
Principal Investigator (PI) (signature) 
 
 
 
Date (dd-MMM-yyyy) 
 
 
Principal Investigator (PI) Name (printed) 
 
 
 
Site Number 
 
 

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LIST OF PERSONNEL AND ORGANIZATIONS RESPONSIBLE FOR 
CONDUCT OF THE STUDY 
A list of personnel and organizations responsible for the conduct of the study will be supplied 
to study sites as part of the Investigator’s Study File. This list will be updated by Spark (or 
delegate) and provided to study sites as needed. 
 
 

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TABLE OF CONTENTS 
 
TITLE PAGE .......................................................................................................................1 
SPONSOR SIGNATORY FORM .......................................................................................2 
INVESTIGATOR STATEMENT .......................................................................................3 
LIST OF PERSONNEL AND ORGANIZATIONS RESPONSIBLE FOR CONDUCT 
OF THE STUDY ..........................................................................................................4 
TABLE OF CONTENTS .....................................................................................................5 
1 
PROTOCOL SUMMARY ............................................................................................9 
1.1 
Synopsis ...................................................................................................................9 
1.2 
Schema ...................................................................................................................20 
1.3 
Schedule of Events .................................................................................................21 
2 
INTRODUCTION ......................................................................................................26 
2.1 
Background ............................................................................................................26 
2.1.1 
Hemophilia A ...................................................................................................26 
2.1.2 
Clinical Manifestations ....................................................................................27 
2.1.3 
Current Therapies and Prevention for Hemophilia A ......................................28 
2.1.4 
Alternative Therapy for Hemophilia A ............................................................30 
2.2 
Rationale ................................................................................................................33 
2.2.1 
Description of SPK-8011 .................................................................................33 
2.2.2 
Summary of Non-Clinical Experience with SPK-8011 ...................................34 
2.2.3 
Summary of Clinical Experience with SPK-8011 ...........................................35 
2.2.4 
Summary of Non-clinical Experience with Tocilizumab ................................36 
2.2.5 
Summary of Non-Clinical and Clinical Experience with Mycophenolate 
Mofetil..............................................................................................................38 
2.3 
Benefit/Risk Assessment .......................................................................................38 
2.3.1 
Risk Assessment ..............................................................................................38 
2.3.2 
Potential Benefit ...............................................................................................46 
2.4 
Study Rationale ......................................................................................................46 
2.5 
Rationale for Dose and Schedule Selection ...........................................................48 
3 
OBJECTIVES AND ENDPOINTS ............................................................................49 
4 
STUDY DESIGN .......................................................................................................51 
4.1 
Overall Design .......................................................................................................51 
4.1.1 
Sequence of Enrollment ...................................................................................51 
4.1.2 
FVIII Incremental Recovery ............................................................................54 
4.1.3 
Corticosteroids .................................................................................................54 
4.1.4 
Screening..........................................................................................................60 
4.1.5 
Three to Seven Days Prior to Day 0 ................................................................60 
4.1.6 
Day -2...............................................................................................................60 
4.1.7 
Dosing Day (Days 0, 1) ...................................................................................60 
4.1.8 
Follow-up Observation Period .........................................................................61 

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4.2 
Study Duration, Enrollment and Number of Sites .................................................61 
4.2.1 
Duration of Study Participation .......................................................................61 
4.2.2 
Total Number of Participants; Sites Projected and Geographic Regions ........61 
4.3 
End of Study Definition .........................................................................................62 
4.4 
Study Stopping Rules .............................................................................................62 
5 
STUDY POPULATION .............................................................................................64 
5.1 
Inclusion Criteria ...................................................................................................64 
5.2 
Exclusion Criteria ..................................................................................................65 
5.3 
Screen Failures .......................................................................................................67 
5.4 
Enrollment of Participants .....................................................................................67 
5.5 
Randomization .......................................................................................................67 
5.6 
Blinding Procedures ...............................................................................................67 
6 
STUDY PROCEDURES/ASSESSMENTS AND SCHEDULE ................................68 
6.1 
Safety Assessments ................................................................................................68 
6.1.1 
Clinical Safety Assessments ............................................................................68 
6.1.2 
Laboratory Safety Assessments .......................................................................68 
6.2 
Additional Assessments .........................................................................................68 
6.2.1 
Joint Assessments ............................................................................................68 
6.2.2 
Hemophilia Joint Health Score ........................................................................69 
6.2.3 
Activity Assessments (Changes in Level of Activity and Hemophilia 
Activities List) .................................................................................................69 
6.2.4 
Participant Questionnaires ...............................................................................69 
6.2.5 
Health-economic Assessment ..........................................................................70 
6.2.6 
Archived Bio-samples ......................................................................................70 
6.3 
Clinical Procedures ................................................................................................70 
6.4 
Screening Period ....................................................................................................72 
6.4.1 
Screening Assessments ....................................................................................73 
6.5 
Three to Seven Days Prior to Day 0 Assessments .................................................75 
6.6 
Day -2.....................................................................................................................75 
6.7 
Dosing Day Assessments (Days 0, 1) ....................................................................75 
6.7.1 
FVIII Dosing ....................................................................................................76 
6.7.2 
Tocilizumab (TCZ) Dosing..............................................................................76 
6.7.3 
Vector Dosing ..................................................................................................76 
6.7.4 
Day 1 ................................................................................................................77 
6.8 
Follow-up Observation Period (Weeks 1-52) ........................................................77 
6.8.1 
Weeks 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 (±2 days) .............................77 
6.8.2 
Weeks 18, 22, 26, 30, 34, 40, 46, 52/End of Study (±2 weeks) .......................78 
7 
STUDY INTERVENTION ........................................................................................80 
7.1 
Description of Study Drug .....................................................................................80 
7.2 
Study Doses ...........................................................................................................80 
7.3 
Dose Schedule and Administration ........................................................................81 
7.4 
Treatment Compliance ...........................................................................................81 
7.5 
Study Drug Storage ................................................................................................81 
7.6 
Study Drug Preparation, Handling and Disposal ...................................................82 

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7.6.1 
Study Drug Preparation....................................................................................82 
7.6.2 
Study Drug Handling and Disposal .................................................................82 
7.6.3 
Accountability and Destruction .......................................................................82 
7.7 
Labeling .................................................................................................................82 
7.8 
Study Compliance ..................................................................................................83 
7.9 
Prior and Concomitant Medications ......................................................................83 
7.9.1 
Concomitant Therapy.......................................................................................83 
7.9.2 
Permitted Therapy ............................................................................................83 
7.9.3 
Prohibited Therapy ...........................................................................................84 
7.9.4 
Concomitant Procedures ..................................................................................84 
8 
DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL ..................................................................85 
8.1 
Participant Discontinuation/Withdrawal from the Study .......................................85 
8.2 
Early Termination Study Visit ...............................................................................85 
9 
Adverse Events and Serious Adverse Events .............................................................86 
9.1 
Definitions..............................................................................................................86 
9.1.1 
Adverse Event ..................................................................................................86 
9.1.2 
Definition of SAE ............................................................................................87 
9.1.3 
Adverse Events of Special Interest (AESI) ......................................................88 
9.2 
Recording and Follow-Up of AE and/or SAE .......................................................89 
9.3 
Safety Classifications .............................................................................................89 
9.3.1 
Assessment of Intensity ...................................................................................89 
9.3.2 
Assessment of Causality ..................................................................................90 
9.4 
Follow-up and Reporting Requirements ................................................................90 
9.4.1 
Follow-up of AEs and SAEs ............................................................................90 
9.4.2 
Reporting of SAEs ...........................................................................................91 
9.5 
Time Period and Frequency for Collecting AE and/or SAE Information .............91 
9.5.1 
Regulatory Reporting Requirements for SAEs ................................................92 
9.5.2 
Pregnancy .........................................................................................................92 
9.6 
Treatment of Overdose ..........................................................................................92 
10 STATISTICAL CONSIDERATIONS .......................................................................93 
10.1 
Statistical Hypotheses ............................................................................................93 
10.2 
Sample Size Determination ....................................................................................93 
10.3 
Analysis Population ...............................................................................................93 
10.4 
Demography and Baseline Disease Characteristics ...............................................93 
10.5 
Primary and Secondary Endpoints .........................................................................94 
10.5.1 
Safety Analysis ................................................................................................94 
10.5.2 
Efficacy Analysis .............................................................................................94 
10.5.3 
Pharmacokinetic Analysis ................................................................................95 
10.6 
Exploratory Endpoints Analysis ............................................................................96 
10.7 
Interim Analyses ....................................................................................................96 
11 SUPPORTING DOCUMENTATION AND OPERATIONAL CONSIDERATIONS97 
11.1 
Regulatory, Ethical and Study Oversight Considerations ......................................97 
11.1.1 
Regulatory and Ethical Considerations ............................................................97 

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11.1.2 
Financial Disclosure .........................................................................................97 
11.1.3 
Informed Consent Process ...............................................................................98 
11.1.4 
Data Protection.................................................................................................98 
11.1.5 
Committees Structure.......................................................................................99 
11.1.6 
Dissemination of Clinical Study Data ..............................................................99 
11.1.7 
Data Quality Assurance ...................................................................................99 
11.1.8 
Source Documents .........................................................................................100 
11.1.9 
Study and Site Closure ...................................................................................100 
11.1.10 
Publication Policy ..........................................................................................100 
12 REFERENCES .........................................................................................................102 
13 APPENDIX ...............................................................................................................114 
13.1 
Factor VIII Infusion Log ......................................................................................114 
13.2 
Hemophilia Activities List and Change in Level of Activity ..............................115 
13.3 
Haem-A-QoL Questionnaire ................................................................................127 
13.4 
EQ-5D-5L Questionnaire .....................................................................................134 
13.5 
Hemophilia Joint Health Score ............................................................................137 
13.6 
Abbreviations .......................................................................................................141 
13.7 
Protocol Amendment History ..............................................................................145 
 
 
LIST OF TABLES 
Table 1 
Clinical Procedures: Safety and Efficacy Assessments ...................................70 
 
LIST OF FIGURES 
Figure 1 
Study Schematic.........................................................................................20 
Figure 2 
The Blood Coagulation Cascade ................................................................27 
Figure 3 
Schematic of SPK-8011 Vector Genome ..................................................33 
 
 
 
 

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1 
PROTOCOL SUMMARY 
1.1 
Synopsis 
Protocol Title:  
Gene-transfer, open-label, dose-escalation study of SPK-8011 [adeno-
associated viral vector with B-domain deleted human factor VIII gene] in 
individuals with hemophilia A 
Protocol Number: 
SPK-8011-101 
Sponsor: 
Spark Therapeutics 
Development 
Phase: 
1/2a 
Name of 
Investigational 
Product: 
SPK-8011 
Study Indication: 
Hemophilia A 
Rationale:  
There is no available cure for hemophilia A.  Natural history data in 
individuals with hemophilia A suggest that circulating factor levels 
approximately 12% of normal may be sufficient to protect against 
spontaneous joint bleeds (den Uijl, 2011). A vector that can safely and 
consistently achieve sustained high levels of FVIII activity, which could 
potentially eliminate spontaneous hemarthroses, is the goal of gene 
transfer in hemophilia treatment. 
The objective of this study is to determine the safety, tolerability, and 
efficacy (transgene-derived FVIII activity levels) of a single intravenous 
(IV) infusion of SPK-8011 in individuals with severe hemophilia A.      
The recent results from an AAV5-mediated B-domain-deleted human 
factor VIII (AAV5-BDD-hFVIII) BMN-270 gene transfer trial for severe 
hemophilia A resulted in sub-therapeutic levels (0.6% FVIII activity 
levels) over 34 weeks in 1 participant at 6x1012 vg/kg (low dose-level),  
transgene FVIII activity levels 2.3% of normal over 26 weeks in 1 
participant at 2x1013 vg/kg (middle dose-level), and lastly, FVIII activity 
levels 5 - 271% of normal in 7 participants at  6x1013 vg/kg (high dose-
level) in the first year after vector infusion (Rangarajan, 2017). However, 
longer-term follow-up has shown a gradual decline in FVIII levels in the 
circulation. Thus, at year 1, 6 out of 7 participants show FVIII within the 

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normal range, and 1 out of 7 in the range of mild hemophilia. At year 3, 1 
out of 7 remains in the normal range, 5 out of 7 are in the mild hemophilia 
range, and 1 out of 7 is in the moderately severe hemophilia range.  At the 
year 3 median of 19.9%, half of the participants are either at or 
approaching expression levels associated with bleeding events. In that 
trial, in order to avoid the asymptomatic rise in hepatic transaminases 
concomitant with the loss of transgene FVIII activity levels, all 7 
participants receiving the highest dose of BMN-270 received a course of 
steroid therapy. Six participants received prophylactic corticosteroid 
regimens starting 3 weeks after the vector administration. These 6 
participants given prophylactic corticosteroids had exposure from 15 
weeks to at least 35 weeks in 1 participant (Pasi, 2020). 
As of 24 November 2020, in this SPK-8011-101 study, participants have 
received SPK-8011 at dose levels 5x1011 vg/kg, 1x1012 vg/kg, 2x1012 
vg/kg, and 1.5x1012 vg/kg. In attempts to avoid the loss of factor VIII 
transgene expression, both reactive and early prophylactic approaches to 
corticosteroid use have been studied. The reactive treatment with 
corticosteroids, generally initiated ~ Weeks 7-11 following vector 
administration, was performed with a relatively limited course of 
prednisone. In contrast to this, when steroids have been initiated at 
approximately 4 weeks after vector administration with a goal of 
prophylactic maintenance of FVIII expression, prolonged tapering of 
corticosteroids has been required to avoid and treat late recurrences of 
apparent hepatocyte-targeted immune response. In the case of some 
patients with a prolonged steroid taper, it has been clinically necessary to 
initiate a steroid sparing regimen(s) (e.g., azathioprine, tacrolimus) to aid 
in the prednisone taper.  
 
Additional investigation is needed to determine whether there is a short 
course immunosuppressive regimen that will reliably control immune 
responses in all patients and allow long-term expression of the donated 
gene. Going forward, administration of SPK-8011 beginning at the 
1.5x1012 vg/kg dose will be explored in 2 cohorts, based on prior clinical 
studies, non-clinical studies summarized in protocol introduction, and 
input from clinical experts in rheumatology, organ transplantation, viral 
immunology, and bone marrow transplantation. Cohorts 1 and 2 will 
receive immunomodulation with mycophenolate mofetil (MMF) or 
tocilizumab (TCZ), respectively, prior to vector infusion in an effort to 
prevent the immune response.  In the follow up period, corticosteroids will 
only be administered if triggered by the clinical observation of increased 
liver transaminases or decreased circulating factor VIII (FVIII). IV 
 
steroids will be preferentially used when clinical and other circumstances 
permit. The ELISpot will not be considered a predictive tool for clinical 
CCI

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decision making independent of other immune triggers.  Oral 
corticosteroids may be used when clinically indicated. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Study Design: 
This is a Phase 1/2a, open-label, non-randomized, dose-escalation study to 
evaluate the safety, tolerability, and efficacy of a single IV infusion of 
SPK-8011 in adult men with severe hemophilia A (as defined in the 
inclusion criteria).  Up to 50 eligible participants will be dosed with a 
single IV infusion of SPK-8011.  
Participants will provide informed consent and undergo screening 
assessments up to 16 weeks prior to SPK-8011 infusion on the Dosing Day 
(Day 0).  All participants will be monitored for a total of 52 (±2) weeks 
(End of Study) after SPK-8011 infusion (see Schedule of Events). 
Week 52 procedures are to be performed only at the EOS Visit.  If the 
long-term follow-up (LTFU) study is not open at the clinical site at the 
time of a participant’s planned Week 52 visit, the participant may remain 
in Study SPK-8011-101. The procedures from Week 46, except for 
collection of immunology samples for enzyme-linked immunospot assay 
(ELISpot), will be performed at Week 52 and every 12 weeks until the 
LTFU study is open. At that time, the Week 52/EOS visit should occur.  
Study Objectives 
and Endpoints:  
Objectives 
Primary 
• To evaluate the safety and tolerability of SPK-8011. 
• To evaluate the efficacy of SPK-8011. 
Secondary 
• To determine the PK characteristics of SPK-8011. 
CCI

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• To characterize the immune response to the vector and transgene 
product. 
Endpoints 
Primary 
• For safety and tolerability: 
o Clinically notable changes from baseline in physical 
examinations and vital signs. 
o Incidence of adverse events, including clinically 
significant abnormal laboratory values. 
o Hepatic 
transaminase 
elevation 
requiring 
immunosuppression. 
• For efficacy: 
o Primary kinetic parameters of peak and steady-state 
FVIII activity levels assessed by coagulation clotting 
assays. 
o Number of FVIII infusions after vector administration. 
o Number of bleeding events (spontaneous and traumatic) 
after vector administration. 
Secondary 
• Additional kinetic assessments will include, but not limited to: 
o Time to achieve steady-state FVIII activity level. 
o Vector shedding of SPK-8011 in bodily fluids. 
• Incidence of immune response to AAV capsid protein and BDD-
hFVIII transgene. 
Exploratory 
• Joint assessments 
• Activities assessments 
• Quality-of-life assessments 
• Health-economic parameters 
• Exploratory inflammatory profiling of plasma and immune 
function gene expression of PBMCs after vector administration 
(ELISpot, and other exploratory biomarkers) 
Study Population: 
This study will be conducted in males with severe hemophilia A (as 
defined in the inclusion criteria) who are ≥ 18 years of age.   
Inclusion/Exclusion 
Criteria: 
Participants must meet the following criteria at screening and prior to 
dosing of SPK-8011 (Day 0) to be eligible for the study: 
1. Be able to understand the purpose and risks of the study and 
provide signed and dated informed consent and authorization to 
use protected health information (PHI) in accordance with national 
and local privacy regulations;  

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2. Be male and ≥ 18 years of age;  
3. Have hemophilia A with: 
a.  < 1% (< 1 IU/dL) endogenous FVIII activity levels as 
historically documented by a certified laboratory or 
screening data results; OR 
b. 1-2% (1-2 IU/dL) endogenous FVIII activity levels and > 
10 bleeding events per year (in the last 52 weeks prior to 
screening); OR 
c. 1-2% (1-2 IU/dL) endogenous FVIII activity levels and on 
prophylaxis;  
4. Have had > 150 prior exposure days (EDs) to any recombinant 
and/or 
plasma-derived 
(pd) 
FVIII 
protein 
products 
or 
cryoprecipitates based on historical data from the medical 
records/history; 
5. Have no prior history of hypersensitivity or anaphylaxis associated 
with any FVIII or IV immunoglobulin administration; 
6. No measurable inhibitor against FVIII at screening (i.e., < 0.6 
Bethesda Units); no confirmed history of clinically significant 
FVIII inhibitor and no clinical signs or symptoms of decreased 
response to FVIII administration (Note: Family history of 
inhibitors is not exclusionary, nor remote (greater than 5 years) 
documentation of a single measurement of Bethesda titer of > 0.6 
BU that is not accompanied by clinical evidence of failure to 
respond to infused FVIII concentrate); 
7. Have acceptable laboratory values sampled at screening and 
reviewed prior to Day 0: 
a. Hemoglobin ≥ 11 g/dL; 
b. Platelets ≥ 100,000 cells/μL; 
c. AST, ALT, alkaline phosphatase ≤ upper limit of normal 
(ULN) at the testing laboratory; 
d. Bilirubin ≤ 1.5x ULN (Bilirubin levels above the 
laboratory’s normal range are acceptable in individuals 
with a documented history or laboratory evidence of 
Gilbert’s Disease);  
e. Creatinine ≤ 2.0 mg/dL; 
f. Absolute neutrophil count (ANC) ≥ 2000 per mm3; 
g. Fibrinogen antigen ≥ 180 mg/dL for TCZ in Cohort 2 
8. Agree to use reliable barrier contraception after the administration 
of SPK-8011 until notified by the Investigator or designee. 

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If any of the following exclusion criteria exist at screening or prior to 
dosing of SPK-8011 (Day 0), participants are not eligible for the study: 
1. Have active hepatitis B or C. All participants must be screened for 
both active hepatitis B and C regardless of prior known history.   
a. Screening for hepatitis B: All participants must have a 
single sample at screening for each of the following tests: 
HBsAg (hepatitis B surface antigen), anti-HBc (total 
hepatitis B core antibody), and a hepatitis B virus (HBV)-
DNA viral assay (nucleic acid test for hepatitis B virus 
DNA). 
i. 
A participant is not eligible if either HbsAg is 
positive or HBV-DNA is positive/detectable. 
ii. 
A participant is eligible if the anti-HBc is 
positive and both HBsAg and HBV DNA are 
negative, as this would be consistent with a 
prior infection of hepatitis B. Anti-HBc must 
be obtained in all participants to discriminate 
between 
acute 
infection 
and 
possible 
reactivation of hepatitis B during the trial 
(e.g., in participants with no prior history of 
hepatitis B). 
b. Screening for hepatitis C: All participants, including 
those who have never been treated or who have completed 
anti-viral therapy for chronic hepatitis C, must have a single 
hepatitis C virus (HCV)-ribonucleic acid (RNA) load assay 
(also referred to as a nucleic acid test [NAT] for HCV 
RNA) at screening.  
i. 
A participant is not eligible if his HCV-RNA 
load assay is positive/detectable.  
ii. 
Participants treated with anti-viral therapy for 
chronic hepatitis C must have completed anti-
viral therapy at least 6 months prior to 
screening and have a negative HCV-RNA at 
the time of screening. 
iii. 
Participants with a documented or self-
reported history of HCV must have a single 
negative HCV-RNA at time of screening. 
2. Currently on antiviral therapy to treat their hepatitis B or C; 
3. Have significant underlying liver disease. A participant is not 
eligible with any of the following documented diagnoses, 
indicative of significant underlying liver disease: 
a. Portal hypertension; or 

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b. Splenomegaly; or  
c. Hepatic encephalopathy. 
Any participant without any of these pre-existing diagnoses must have 
the following performed at screening: 
3a. 
Serum albumin measurement.  A participant is not eligible if the 
serum albumin level is below the lower limit of normal of the 
laboratory; and  
3b. A diagnostic test for liver fibrosis (e.g., FibroScan, 
FibroTest/FibroSURE, or AST-to-Platelet Ratio Index (APRI)).  
A participant is not eligible if any of the following findings, 
which are indicative of fibrosis ≥ stage 3, are present: 
i. 
FibroScan score > 8.3 kPa units; or 
ii. 
FibroTest/FibroSURE > 0.48; or 
iii. 
AST-Platelet Ratio Index (APRI) > 1 
If more than 1 diagnostic test result is available, then the FibroScan 
will be used as the primary consideration for eligibility. 
4. Have serological evidence of human immunodeficiency virus 
(HIV)-1 or HIV-2 with CD4+ counts ≤ 200/mm3. Participants who 
are HIV-positive and stable, with an adequate CD4+ count (> 
200/mm3) and undetectable viral load (< 50 gc/mL) measured 
twice in the 6 months prior to enrollment, and who are on an 
antiretroviral drug regimen are eligible to enroll;    
5. Have anti-AAV-Spark200 neutralizing antibody titers ≥ 1:1; 
6. Have history of active cancer in the past 6 months, chronic 
infection, latent or active tuberculosis, uncontrolled immune 
disorder or other chronic disease that the Investigator and/or 
Sponsor considers to constitute an unacceptable risk; 
7. Have been dosed in a previous gene therapy research trial within 
the last 52 weeks or participated in a clinical study with an 
investigational drug within the last 12 weeks prior to signing the 
informed consent; 
8. History of diverticulitis, diverticulosis requiring antibiotic 
treatment, or chronic ulcerative lower gastrointestinal disease that 
might predispose a patient to perforations; 
9. Any concurrent clinically significant major disease (such as liver 
abnormalities, type I diabetes, uncontrolled hypertension, vertebral 
compression) or other condition such as active infections or 

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COVID-19 or any other unspecified reasons that, in the opinion of 
the Investigator and/or Sponsor, makes the participant unsuitable 
for participation in the study. At the time of screening, the 
investigator will consider the local geographic and institutional 
epidemiology of coronavirus disease caused by severe acute 
respiratory syndrome coronavirus (SARS-CoV) 2 (COVID-19) 
and other infectious pathogens when determining suitability of the 
participant for participation in the study, including consideration 
of the potential clinical relevance of additional screening; 
10. Planned surgical procedure in the next 12 months requiring FVIII 
prophylactic treatment; and 
11. Unable or unwilling to comply with the schedule of visits and study 
assessments described in the clinical protocol. 
Study Duration: 
The total duration of the study is approximately 68 (±2) weeks, including 
screening.  The study will include the following phases: 
a) Screening period (up to a maximum of 16 weeks);  
b) Dosing day (Day 0); 
c) Follow-up observation period [52 (±2) weeks].   
Planned Number of 
Participants: 
Up to 50 evaluable participants will be dosed with a single intravenous 
infusion of SPK-8011. 
Number and 
Location of Study 
Sites: 
The study is planned to be conducted at approximately 20 study centers 
(vector-administration centers and/or follow-up centers) worldwide. 
Sequence of 
Enrollment: 
Two staggering strategies are employed in this study: 
a) The first 2 participants in each dose level will be infused with SPK-
8011 at least 6 weeks apart to mitigate acute safety risk; and 
b) There will be at least 6 weeks of staggering between each dose 
level.  The Data Monitoring Committee (DMC) will review at least 
6 weeks of follow-up data from up to 4 participants who have 
received SPK-8011 at a given dose level prior to infusing the first 
participant in the next dose level. 
c) Continued enrollment will alternate between Cohorts 1 and 2 
beginning at 1.5x1012 vg/kg. A stagger of at least 6 weeks will 
occur between the first and the second participants in Cohort 2 (see 
Figure 1). 
d) HIV positive individuals with stable CD4+ count > 200 mm3 are 
eligible provided all other inclusion criteria are met. However, they 
will not be enrolled as the first 2 participants in Cohort 2. 

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Criteria for 
Evaluation: 
Safety Evaluation: 
Safety assessments will include physical examination, vital signs, adverse 
events, measurement of antibodies against FVIII, immune responses 
against transgene product and/or vector, vector shedding of bodily fluids, 
laboratory parameters changes over time, and the use of any 
immunosuppressive therapy.  
The infusion of SPK-8011 to the first 2 participants at each dose level will 
be staggered by at least 6 weeks to mitigate acute safety risk.  Additionally, 
at least 6 weeks of follow up data from up to 4 participants in a given dose 
level will undergo review by the DMC prior to infusing the first participant 
in the next dose level. 
Pharmacokinetic Evaluation: 
The responses to SPK-8011 will consist of peak and steady-state values of 
circulating vector-derived FVIII activity levels after SPK-8011 infusion. 
Additional pharmacokinetic (PK) evaluation of SPK-8011 is carried out 
by analysis of serum, urine, semen, saliva, and peripheral blood 
mononuclear cells (PBMCs) for the presence of vector DNA.  
Efficacy Evaluation: 
The following information will be collected for efficacy evaluations: 
• Vector-derived factor VIII in circulation (FVIII:C) activity levels 
(including peak and steady-state levels) 
• FVIII antigen level  
• Number of FVIII infusions (prophylaxis and/or on-demand) 
o Number of bleeding episodes (spontaneous and traumatic) 
o Annualized FVIII usage (AFU) 
o Annualized bleeding rate (ABR) (spontaneous and traumatic) 
• Joint assessments 
• Activities assessments 
• Quality-of-life assessments 
• Health-economic assessments 
Investigational 
Product 
Description: 
SPK-8011 is a recombinant adeno-associated viral (rAAV) vector 
designed to drive expression of a B-domain deleted human factor VIII 
(BDD-hFVIII) transgene and raise the circulating activity levels of 
endogenous 
FVIII.  
SPK-8011 
is 
comprised 
of 
a 
bio-
engineered rAAV capsid (AAV-Spark200) and an expression cassette 
encoding 
B-domain-deleted, 
codon-optimized 
human 
FVIII 
(hFVIII).  Dose-ranging studies in non-human primates (NHPs) infused 
with SPK-8011 have shown average hFVIII antigen levels that peaked 
approximately 2 to 3 weeks after infusion, with levels ranging from 22.3 
± 6.2% of normal, with a dose of 2x1012 vg/kg, to 153 ± 58.1% of normal, 

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with 
highest 
dose 
of 
2x1013 vg/kg 
without 
observed 
safety 
concerns.   More recently, chimeric ‘humanized’ mice with livers partially 
repopulated with human hepatocytes have become available as a tool to 
determine hepatic transduction efficacy of different viral capsids. 
 
 
 
 Thus, the 
Sponsor suggests an initial starting dose level of 5x1011 vg/kg, assuming a 
linear extrapolation of FVIII levels in humans to be approximately 3% of 
normal.  
Dose Expansion / 
Escalation Plan: 
Each dose level is planned to enroll and dose a minimum of 2 participants. 
The first 2 participants at each dose level will be dosed at least 6 weeks 
apart to ensure the safety and tolerability of the vector administration. 
Dose-Level and Cohort Expansion- 
Dose-level expansion may occur under the following scenarios: 
A. Dose-Level Expansion - After 2 participants are dosed in a given 
dose-level, it may be possible to expand a dose-level to up to 10 
participants if there is evidence of FVIII:C increases above 5% of 
normal in either participant by Week 4 post vector-administration.  
This initial expansion will provide additional information about the 
variability of responses within the same dose-level.  
B. New Cohort Expansion – After 2 participants are dosed in a cohort, 
an initial expansion of up to 3 participants may occur and, thereafter, 
an additional expansion for up to a total of 10 participants may occur. 
The additional expansion may occur in 1 or more cohorts.  
Dose Escalation-  
The decision to dose escalate will be made by the Sponsor in consultation 
with the DMC to ensure safety. 
Dose escalation to the next dose level may occur under the following 
scenarios, provided there are no safety concerns after at least 6 weeks of 
follow-up data have been reviewed by the DMC. Dose escalation through 
the first 3 dose levels (5.0x1011 vg/kg, 1.0x1012, 2.0x1012 vg/kg) may occur 
in, but is not restricted to, the following scenarios. 
Dose escalation may be considered if: 
a) If neither of the first 2 participants achieve FVIII:C above 5% of 
normal by Week 6 post vector-administration; or 
b) If at least 2 participants in a given dose-cohort achieve FVIII:C ≤ 
40% of normal by Week 6 post-vector-administration; or 
c) If 3 participants in a given dose-cohort achieve ‘steady-state 
FVIII:C < 50% of normal. 
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There will be no dose escalation if at least 3 participants in any dose level 
achieve ‘steady-state’ FVIII:C   > 80% of normal. Steady-state levels are 
based on at least 2 separate FVIII:C measurements, at least 2 weeks apart, 
starting 8-12 weeks post vector administration and without use of 
exogenous FVIII product since vector administration. 
After escalation through the first 3 planned dose levels, an intermediate 
dose level (e.g., 1.5x1012 vg/kg of SPK-8011), was agreed upon by the 
DMC. Additionally, the Sponsor may decide to further expand the starting 
dose cohort (5x1011 vg/kg), the middle dose cohort (1x1012 vg/kg), or the 
high dose cohort (2x1012 vg/kg) to better evaluate the safety, efficacy, and 
variability of response within a given cohort.   Any decision to add an 
intermediate dose level or further expand one of the existing protocol-
defined dose levels will be made in consultation with the DMC. In 
consultation with the DMC, further dose exploration may be considered if 
effective immunomodulation has been demonstrated in any cohort and/or 
FVIII expression is less than 80% of normal 12 weeks following gene 
transfer in at least 2 participants. 
Data and Safety 
Monitoring Plan: 
The independent DMC is composed of at least 3 independent experts in 
hemophilia or immunology. The independent DMC will be responsible for 
reviewing safety and efficacy data, as well as 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.  
Statistical 
Methods: 
Statistical analyses will be primarily descriptive in nature.  Summary 
statistics will be presented for all safety endpoints and vector-derived 
FVIII:C activity levels over time after SPK-8011 administration. 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. 
In general, descriptive statistics including number of observations, mean, 
standard deviation, median, minimum, and maximum will be presented for 
continuous parameters.  Categorical parameters will be displayed using 
counts and percentages within each category. 
Interim analyses may be performed after 2 participants in a given dose 
cohort complete Week 12.  
 
 
 

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1.2 
Schema 
Figure 1 
Study Schematic 
Screening 
Dosing1 
 
 
FVIII 
Infusion 
50 IU/kg 
Day 0 
SPK-8011 
Infusion 
5x1011 vg/kg 
1x1012 vg/kg 
2x1012 vg/kg 
Day 0 
 
Screening 
Dosing1,2 
 
 
 
FVIII 
Infusion 
50 IU/kg 
Day 0 
SPK-8011 
Infusion 
1.5x1012 vg/kg 
Day 0 
 
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1.3 
Schedule of Events 
Tests and Assessments 
Screen1 
Weeks 
-16 to -1 
 3 to 7 
Days 
prior 
to Day 
0  
Day 0 
Day 
1 
Week 1 – 16 (±2 days)3 
Week 18–52 (±2 weeks)3 
FVIII 
Dosing 
 Pre-
SPK-
8011 
Dosing 
SPK-
8011 
Dosing 
30 (±2) 
min, 2 and 5
hrs 
(±10 min) 
from stop of
SPK-8011 
infusion 
24 hrs 
(±1hr)  
 
1 
2, 3, 4, 5, 6 
7 
8, 9, 10, 
11 
12 
14 16 18 22 26 
30 
34 
40 
46 
52/ 
EOS2,23 
A 
B 
A 
B 
A 
B 
A 
B 
 
 
 
 
 
 
 
 
 
 
 
Informed consent4 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Review inclusion/exclusion 
criteria 
X 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Demographics, medical and 
hemophilia history5 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Genotype, HLA, if not 
known5 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Target joint assessment,  
HJHS 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
 
 
X 
Physical exam, height, 
weight8 
X7 
 
 
 X 
 
 
 
X 
 
 
 
X 
 
 
 
X 
 
 
X  
X 
 
X 
X 
 
X 
Vital signs 
X 
 
 
 X9 
 
X9 
X9 
X 
 
 
 
X 
 
 
 
X 
X X X X X 
X 
X 
X 
X 
X 
α-fetoprotein (CL) 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
Liver ultrasound (if 
indicated)13 
X  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
HBsAg, anti-HBc, HBV-
DNA (CL)  
X10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X28  
 
 
 
 
 
 
 
 
 
HCV-RNA load assay (CL) 
X10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HIV-1/HIV-2 Ag/Ab (CL) 
X10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CD4+ count, HIV-1/HIV-2 
viral load (for positive 
participants only) (CL)  
X10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hematology (CL, LL)25 
X 
X24 
 
 
 
 
X 
X 
 
 
 
X 
 
 
 
X 
X X X  
X 
 
 
 
 
X 
Clinical chemistry (CL)  
X 
 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
X 
 
 
X  
X 
 
 
 
 
X 
Urinalysis (CL) (using 
dipstick)  
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
 
 
X 
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Tests and Assessments 
Screen1 
Weeks 
-16 to -1 
 3 to 7 
Days 
prior 
to Day 
0  
Day 0 
Day 
1 
Week 1 – 16 (±2 days)3 
Week 18–52 (±2 weeks)3 
FVIII 
Dosing 
 Pre-
SPK-
8011 
Dosing 
SPK-
8011 
Dosing 
30 (±2) 
min, 2 and 5
hrs 
(±10 min) 
from stop of
SPK-8011 
infusion 
24 hrs 
(±1hr)  
 
1 
2, 3, 4, 5, 6 
7 
8, 9, 10, 
11 
12 
14 16 18 22 26 
30 
34 
40 
46 
52/ 
EOS2,23 
A 
B 
A 
B 
A 
B 
A 
B 
 
 
 
 
 
 
 
 
 
 
 
Fibrinogen Ag, thrombin 
time, D-dimer35 (LL) 
X 
 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Coagulation – aPTT and 
FVIII activity (CL, LL), 
FVIII Ag (CL)11 
X 
 
 
X17 
 
 
X 
X X 
X 
X 
X 
X X X X 
X X X X X 
X 
X 
X 
X 
 
X 
Coagulation - FVIII 
inhibitor (CL, and LL at 
screening), VWF activity 
and VWF Ag (CL) 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
LFTs and CRP (LL and 
CL)11 
X 
X24 
 
 
 
 
X 
X X 
X 
X 
X 
X X X 
X X X X X X 
X 
X 
X 
X 
X 
Immunology (CL)  
 
X24 
 
X 
 
 
X 
X 
 
X 
 
X 
 
X 
 
X X X X X X 
X 
X 
X 
X 
X 
ECG (if indicated)12 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Liver fibrosis diagnostic 
test13 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lipid panel, (if indicated) 
(LL, CL)14,25 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
AAV neutralizing Ab 
(CL)31 
X 
 
 
 
 
 
 
X 
 
X 
 
X 
 
 
 
X X 
 
 
 
X 
 
 
X 
 
X 
Vector shedding (CL)15  
 
 
 
X 
 
X 
 
X 
 
   <<< if indicated >>> 
Immune profiling (CL)29,32 
 
X24 
 
X 
 
X 
X 
 
X 
 
X 
 
 
 
X 
 
 
X  
 
 
 
 
 
 
 
PAX gene (RNA) (CL)30,32 
 
X 
 
X 
 
X 
X 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
Spare plasma (CL)21 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
X 
 
 
 
 
X 
 
 
X 
 
X 
TPMT (LL) 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TB testing (LL) 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
SARS-CoV2 testing (LL)33 
X 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 X  
 
 
 
 
 
 
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Tests and Assessments 
Screen1 
Weeks 
-16 to -1 
 3 to 7 
Days 
prior 
to Day 
0  
Day 0 
Day 
1 
Week 1 – 16 (±2 days)3 
Week 18–52 (±2 weeks)3 
FVIII 
Dosing 
 Pre-
SPK-
8011 
Dosing 
SPK-
8011 
Dosing 
30 (±2) 
min, 2 and 5
hrs 
(±10 min) 
from stop of
SPK-8011 
infusion 
24 hrs 
(±1hr)  
 
1 
2, 3, 4, 5, 6 
7 
8, 9, 10, 
11 
12 
14 16 18 22 26 
30 
34 
40 
46 
52/ 
EOS2,23 
A 
B 
A 
B 
A 
B 
A 
B 
 
 
 
 
 
 
 
 
 
 
 
Infusion with FVIII 
product16 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Infusion with SPK-801118 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hemophilia Activities List, 
Health-economic 
Assessment19 
X 
 
 
 
 
 
 
 
 
 
X 
 
 
 
X 
X 
 
 
 
X 
 
 
X 
 
X 
Haem-A-QoL, EQ-5D-5L19 
X6 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
 
 
X 
PK profile 
X34 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dispense/review/collect 
FVIII Infusion Log20 
X 
 
 
X 
 
 
 
 
 
 
 
X 
 
 
 
X 
X 
 
 
 
X 
 
 
X 
 
X 
Adverse events 
X 
ongoing 
Prior and concomitant 
therapies/procedures 
X 
ongoing 
Unscheduled visit or safety 
test22 
 
 
 
 
 
 
if indicated 
AAV = adeno-associated virus, Ab = antibody, Ag = antigen, ALT = alanine aminotransferase, aPTT = activated partial thromboplastin time, AST = aspartate 
aminotransferase, CL = central lab (refer to Laboratory Manual), CD4+ = cluster of differentiation 4, CRP = C-reactive protein, CTL = cytotoxic T-lymphocyte, 
ECG = electrocardiogram, EOS = end of study, EQ-5D-5L = EuroQol- 5 Dimension 5 Level, FVIII = coagulation factor VIII, GGT = gamma-glutamyl 
transferase, Haem-A-QoL = Haemophilia A Quality of Life, HBc = hepatitis B core, HBs = hepatitis B surface, HBV = hepatitis B virus, HCV = hepatitis C 
virus, HDL = high-density lipoprotein, HIV = human immunodeficiency virus,  HJHS = Hemophilia Joint Health Score, HLA = human leukocyte antigen, IV = 
intravenous, LDH = lactate dehydrogenase, LDL = low-density lipoprotein, LFT = liver function test, LL = local lab, LTFU = long-term follow-up, 
 
NAAT = nucleic acid amplification testing, PBMC = peripheral blood mononuclear cells, PCR = polymerase chain reaction, PK = 
pharmacokinetic,  SARS-CoV2 = severe acute respiratory syndrome coronavirus 2, TB = tuberculosis, 
, TPMT = thiopurine 
methyltransferase, VLDL = very low-density lipoprotein, VWF = von Willerbrand Factor.    
 
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Notes for Schedule of Events: 
1. The screening period may be up to 16 weeks. If the screening period exceeds 16 weeks, then the participant must repeat all screening procedures.   
2. EOS is at the Week 52 visit. If a participant discontinues the study prior to Week 52, EOS procedures must be performed within the timeframe of the next scheduled 
visit.  If EOS does not occur at Week 52, see footnote 23. 
3. Any follow-up visit requiring a physical exam must be performed at the study center. All other visits without a physical exam, including Weeks 1B-6B and 7B-11B, 
may be performed by a qualified and trained in-home service provider.  
4. Informed consent must be obtained prior to any study-related procedures.   
5. Screening genotype and/or HLA samples will be collected only if not known. Investigator and participant to review age-appropriate vaccinations during the screening 
period, and at least 4 weeks prior to planned day of administration of SPK-8011.  
6. Assessments are completed between screening visit and prior to Dose Day 0. Joint assessments and lab collection for vector shedding is allowed on Day 0 pre-SPK-
8011 Dosing. 
7. Height is measured only at screening.  
8. At Day 0, weight obtained from screening (or the weight obtained from the most recent visit prior to infusion) will be used to calculate the dose of FVIII product and 
SPK-8011.  Physical Exam is comprehensive (not targeted), at all designated visits. Hemophilic arthropathy should be assessed during the physical exam. 
9. At Days 0 and 1, vital signs (i.e., blood pressure, pulse, respiratory rate, and oral/temporal temperature), are measured after the participant has been resting upright or 
supine for approximately 5 min at the following timepoints: SPK-8011: Pre-infusion and post-infusion of SPK-8011 (i.e., 30 min (±2 min), 2 hrs (±10 min), and 24 
(±1) hrs)  
10. Screening serology will be performed as follows:  For all participants: HBsAg, anti-HBc, HBV-DNA, HCV-RNA load assay, HIV-1/HIV-2 Ag/Ab; For HIV-positive 
participants: CD4+ count and HIV-1/HIV-2 viral load. LL results may be used for eligibility assessment. 
11. Screening LFTs will be performed by CL and LL. Twice weekly monitoring of AST, ALT, GGT, LDH, aPTT, FVIII:C, and FVIII Ag will be performed during Weeks 
1 through 11 post vector-infusion visits. LL results may be used for eligibility assessment. LFTs on 3-7 days prior to Day 0 are performed by the local lab only. 
12. Screening ECG is required for participant > 50 years of age, or if clinically indicated.    
13. Screening FibroScan (LL), FibroTest/FibroSURE (CL), or AST-to-Platelet Ratio Index (LL) is required for participants without known pre-existing diagnosis of portal 
hypertension, splenomegaly, or hepatic encephalopathy. For liver ultrasound, "if indicated" means "if, in the judgment of the investigating site or the sponsor, the liver 
ultrasound is indicated to aid interpretation of the screening evaluation of liver fibrosis”. 
14. Lipid panels (total cholesterol, HDL, LDL, VLDL, triglycerides) will be performed for participants with a history of dyslipidemia or hypercholesterolemia, or if 
clinically indicated. 
15. Vector shedding:  PCR analysis will be performed; PBMC, serum, saliva, urine, and semen will be collected between screening and Day 0 (prior to vector infusion) 
and weekly starting at Week 1 post-vector infusion and continuing until 3 consecutive samples are negative (classified as: at or below the limit of detection of the 
assay).   
16. The morning of Day 0, or 
 for Cohort 2, participants will administer a single prophylactic IV infusion of approximately 50 IU/kg of FVIII product. This 
may be self-administered and recorded in the participant’s Infusion Log.  Site assistance is permitted for the FVIII infusion. 
17. Day 0 blood samples for FVIII activity, FVIII Ag, and aPTT will be collected pre-SPK-8011 infusion. 
18. Participants will receive a single IV infusion of SPK-8011 for approximately 60 (±2) min. 
19. Quality-of-life questionnaires (Hemophilia Activities List, Haem-A-QoL, EQ-5D-5L) will be completed by the participants. 
20. Training and dispensation of FVIII Infusion Log at screening or Day 0 (pre SPK-8011 infusion), with collection, review, and dispensing at subsequent visits. 
21. Spare plasma will be collected for immunology, further coagulation assays, future research, or for clarification of any clinical or laboratory adverse events. 
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22. Unscheduled visits or safety tests may be performed for safety monitoring purposes or repeat safety assessments.   
23. Week 52 procedures are to be performed only at the EOS Visit.  If the LTFU study is not open at the clinical site at the time of a participant’s planned Week 52 visit, 
the participant may remain in Study SPK-8011-101. The procedures from Week 46, except for collection of immunology samples for ELISpot, will be performed at 
Week 52 and every 12 weeks until the LTFU study is open. At that time, the Week 52/EOS visit should occur.  
24. Local hematology, local LFT, and central immunology, and immune profiling must be obtained 3 to 7 days prior to Day 0. A remote service provider may be used for 
this visit. Contact the participant to verify no changes in the general health status prior to 
 
25. Weekly hematology and monthly lipid profile should be monitored locally for Cohorts 1 and 2 until 
. The frequency may be altered 
based on clinical response. 
 
 
 
  
28. Participants in Cohorts 1 and 2 will be retested at 12 weeks for HBsAg and anti-HBc.  
29. Samples for immune profiling will be collected 
 pre-administration of SPK-8011, and 30 (±2) min, 2 hrs (±10 min), 5 
hrs (±10 min), and 24 (±1) hrs post vector infusion, and Weeks 1B, 2B, 3B, 4B, 8B, and 16. 
30. Samples for PAX gene will be collected 
 pre- administration of SPK-8011, 5 hrs (±10 min), and 24 (±1) hrs post vector 
infusion, and Weeks 2B, 4B, and 8B. 
31. Samples for AAV neutralizing antibody will be collected during screening, then Week 1A, Week 2A, Week 4A, Week 7A, then Weeks 12, 14, 26, 40, and 52/EOS 
32. If an apparent CTL immune response/liver inflammation is observed and triggers the initiation of reactive corticosteroids, additional samples will be collected for 
immune profiling and PAX gene at the following times: prior to initiating 
 IV corticosteroids or oral corticosteroids (if possible, without delaying the initiation of 
corticosteroid therapy) and then 
 following initiation of corticosteroids.  
33. Anti-SARS-CoV2 serology testing will be done at screening and at Week 18. At the discretion of the investigator, NAAT for infection with SARS-CoV2 may be 
performed 3 to 7 days prior to Day 0 (Cohort 2 only) and prior to the initiation of reactive corticosteroids. 
34. If the PK profile is not available in historical records on the current FVIII product, the participant must undergo a PK analysis locally between screening and Day 0. 
35. Fibrinogen Ag, thrombin time, D-dimer are required locally at screening, Week 2A, and Week 4A for participants enrolled in Cohort 2. 
 
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2 
INTRODUCTION 
SPK-8011, an investigational gene transfer medicinal product, is a rAAV vector that contains a 
bioengineered capsid (AAV-Spark200) and a codon-optimized expression cassette to drive 
expression of human coagulation factor VIII (FVIII). SPK-8011 is being developed by Spark 
Therapeutics for the treatment of hemophilia A.  The Guidance for Industry: Considerations for 
the Design of Early-Phase Clinical Trials of Cellular and Gene Therapy Products (U.S. Food and 
Drug Administration, 2015) and findings from previous clinical studies with AAV2, AAV8 and 
AAV-Spark100 vectors were considered in the development of this protocol. 
2.1 
Background 
2.1.1 Hemophilia A  
Hemophilia A is an X-chromosome linked bleeding disorder that primarily affects 1 in 5,000 male 
births (Giangrande, 2005; Srivastava, 2013).  The severity of disease is characterized by the 
endogenous level of factor VIII (FVIII) measured in the plasma.  Severe hemophilia A is defined 
as a coagulation activity of FVIII in plasma (FVIII:C) level of < 1% (< 1 IU/dL) normal levels.  
Factor VIII, a single chain glycoprotein pro-cofactor, is composed of 6 putative domains arranged 
in the order of heavy chain (A1, A2, and B regions) and light chain (A3, C1, and C2 regions).  The 
light chain (Lollar, 1988) contains binding sites for von Willebrand factor (VWF), activated 
protein C (Walker, 1990), activated factor IX (FIXa), and phospholipid (Foster, 1990).  FVIII and 
VWF circulate in plasma as a non-covalently-linked complex which stabilizes the intrinsically 
unstable FVIII protein.  Observations that the FVIII-VWF complex is dissociated by phospholipid 
and that VWF prevents FVIII from binding to phospholipid and platelets suggests antagonism 
between phospholipid and VWF for binding to FVIII.  Although FVIII and VWF are 
glycoproteins, they have different roles in the initiation and regulation of hemostasis.  VWF is 
necessary for mediation of platelet-vessel interactions at the site of vascular injury.  Thrombin 
FIXa each activate FVIII functions by cleaving the light chain at amino acid residue 1689. This 
cleavage releases FVIII from VWF and allows binding of FVIII to phospholipid resulting in the 
formation of the tenase activated factor X (FXa) complex. This is the central step in the coagulation 
cascade.  The coagulation cascade has 2 pathways, the Activation Pathway (Intrinsic Pathway) and 
the Tissue Factor Pathway (Extrinsic Pathway) (Makaryus, 2013). The plasma factors normally 
circulate in inactive forms but are activated in a cascade or “waterfall” of amplifying reactions 
(Macfarlane, 1964; Davie, 1964) one after the other until the soluble plasma protein, fibrinogen, 
is transformed into a fibrinous clot.  The blood coagulation cascade is illustrated in Figure 2.  
 
 

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Figure 2 
The Blood Coagulation Cascade  
 
Although platelets are critical to the formation of the hemostatic plug, an effective clot cannot be 
formed without adequate levels of pro-coagulant factors.  The level of coagulation factors in the 
plasma of normal individuals ranges from 50 - 150% (or 50 -150 IU/dL) of the level in normal 
pooled plasma.  Therefore, clinical features and factor coagulant activity define the severity of the 
disease. 
2.1.2 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 (ICH). Individuals with 
FVIII:C ≤ 2% of normal experience frequent life-threatening spontaneous and traumatic bleeding, 
particularly in joints, soft tissues, and muscles.  When inadequately managed, musculoskeletal 
hemorrhages can lead to recurrent hemarthroses (chronic arthropathy) and the development of 
target joints (generally accepted criterion is a minimum of 3 bleeds into a single joint within a 
consecutive 6-month period [Blanchette, 2014]). 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 
(Fogarty, 2011).  ICH 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.  ICH can occur after trauma, but as 
many as 50% of cases occur spontaneously (Stieltjes, 2005).   

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Development of alloantibodies to FVIII (i.e., inhibitors) is the main complication of any factor 
replacement therapy (Goudemand, 2006; Kessler, 1991; White, 2005).  Inhibitory antibodies 
(usually immunoglobulin G subclass 4 (IgG4) antibodies that neutralize the procoagulant activity 
of FVIII or coagulation factor IX (FIX)) to FVIII are estimated to occur in 20-35% of individuals 
with severe and mild-to-moderate hemophilia A, respectively (Gouw, 2013; van den Berg, 2013; 
Mancuso, 2012; Hay, 2011), following exposure to factor replacement therapy.  In the presence of 
inhibitory antibodies, replacement of the missing clotting factor by infusion of FVIII becomes less 
effective.  Once replacement therapy is ineffective, acute management of bleeding requires agents 
that bypass FVIII activity.  Long-term management of inhibitors in hemophilia A typically consists 
of eradicating the inhibitor through immune tolerance.  Therefore, development of inhibitors 
significantly adds to patients’ disease burden.   
2.1.3 Current Therapies and Prevention for Hemophilia A 
2.1.3.1 Current Therapies 
There is no available cure for hemophilia A.  Factor replacement therapy, purified from human 
plasma, first became available more than four decades ago.  Although these FVIII products 
dramatically improved life expectancy and QoL in the U.S.A. and Western Europe, they also 
resulted in exposure of individuals with hemophilia to blood borne viruses – most significantly 
hepatitis B, hepatitis C, and the human immunodeficiency virus (HIV).  HIV sero-conversion 
studies documented that most individuals with hemophilia were infected between 1978 and 1984 
(Eyster, 1985; Ragni, 1986; Ragni, 1987).  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 A born before 1987.  Late complications of HCV are an increasing cause of death 
in adults who have been infected for decades (Brettler, 1990; Darby, 1997).   
In the 1990’s, concerns about viral contamination (Mannucci, 2001) prompted 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 
transmission (Roth, 2001; White, 1998).  Indeed, there have been no documented transmissions of 
hepatitis B and C viruses, HIV, West Nile, or malaria since the introduction of effective virus 
inactivation procedures (Tabor, 1999).  However, there is no pathogen inactivation process that 
has been shown to eliminate all pathogens (such as rare reports of infectious prions and parvovirus 
transmission).  However, these products have not circumvented all of the problems of protein-
based therapies (Mannucci, 1993a; Mannucci, 1993b).  
Current treatment of the disease is based on venipuncture and intravenous administration of either 
plasma-derived or recombinant FVIII (rFVIII) protein replacement home therapy to raise the 
circulating FVIII (FVIII:C) activity level to the lowest effective dose to achieve either resolution 
of bleeding (on-demand treatment) or prevention of bleeding (prophylaxis treatment) (Roberts, 
1993; Srivastava, 2013; National Hemophilia Foundation, 2007). Venous access via peripheral 
veins remains the preferred option for the administration of FVIII products (Komvilaisak, 2006) 

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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 FVIII 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 Hemophilia (Srivastava, 2013) established 
recommendations of plasma factor levels and duration of administration for different types of 
bleeds based on observations over the years.  Improvements in FVIII replacement therapy, have 
vastly increased the QoL and life expectancy of individuals with hemophilia A; a recently licensed 
modified FVIII agent with extended half-life (EHL) (Mahlangu, 2014) provided more convenient 
dosing options (Lambert, 2007).   
2.1.3.2 Current Prevention 
Chronic arthropathy is the major morbidity of the disease resulting from recurrent spontaneous 
bleeds into the joints.  Many studies have shown that, even at high doses, on-demand therapy is 
not effective in preventing arthropathy (Petrini, 1991; Aledort, 1994). The introduction of rFVIII 
concentrates in the early 1990’s facilitated the use of scheduled protein replacement to prevent 
bleeding (prophylaxis treatment) as the standard of care for hemophilia rather than on-demand 
treatment.  Prophylaxis treatment (regular IV infusions ranging from twice a week up to every 
other day) aims to maintain plasma FVIII levels ≥ 1%, thereby changing the expected phenotype 
from severe to moderate hemophilia (Nilsson, 1992).  Observations of individuals with moderate 
hemophilia, and a generation of clinical research in hemophilia patients treated prophylactically 
with clotting factor replacement, have documented that minimal elevations in the levels of normal 
circulating clotting factor activity > 1% are sufficient to prevent bleeding as demonstrated in the 
Swedish prophylaxis studies summarized in Löfqvist, 1997; Ljung, 1998; and Nilsson, 1992.   
Prophylactic therapy has revolutionized health outcomes in hemophilia by enabling affected 
individuals to participate in physical activities and natural history data suggested FVIII:C around 
12% of normal may be sufficient to protect from spontaneous joint bleeds (Madhi, 2015; den Uijl, 
2011).  However, regular replacement therapy poses significant challenges for the hemophilia 
community, including the frequency of IV infusions required, the necessity to adhere rigorously 
to the prophylactic regimen, variability in individual pharmacokinetics (PK) requiring 
personalized regimens, potential development of neutralizing alloantibodies (“inhibitors”), and 
cost-effectiveness.   
Prophylaxis, which aims to convert the severe phenotype to moderate through regular infusions of 
clotting factor, with 100% adherence in dosing regimen is more effective than on-demand at 
preserving joint health (Manco-Johnson 2007; Gringeri, 2011) and has enabled affected 
individuals to participate more extensively in physical activity (Wang, 2016; Negrier, 2013). 
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. As of 2014, an estimated 85% of 
children and 63% of adults with hemophilia were on prophylactic regimens (World Federation 
Hemophilia (WFH) Annual Global Survey 2015). The expense of prophylaxis may be prohibitive; 
the cost of prophylactic treatment for an adult (70 kg) can be as high as $630,630 annually using 
the currently available EHL FVIII fusion proteins, respectively (Croteau, 2015). Furthermore, the 

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burden of treatment on patients is great.  Prophylaxis with either regular or EHL rFVIII protein 
(half-lives ranges 10.8 -19.7 hours) typically requires 2-3.5 infusions per week (National 
Hemophilia Foundation, 2016). In a 2001 survey of 38 hemophilia patients on prophylaxis, only 
60% reported infusing at least three fourths of the recommended factor, commonly missing doses 
due to time commitment and complexity (Hacker, 2001).  Recent results from a multi-center study 
assessing adherence to prophylaxis and clinical outcomes in The Netherlands revealed only 43% 
of the patients adhered to the prophylactic regimen (Schrijvers, 2016), despite the fact that poor 
adherence resulted in significantly greater number of bleeding episodes and lower physical health 
status (Krishnan, 2015).   
2.1.4 Alternative Therapy for Hemophilia A 
In the case of hemophilia, where a cure is currently not attainable and lifelong therapy is needed, 
QoL is an essential outcome parameter.  All hemophilia prophylaxis studies using health-related 
quality-of-life (HR-QoL) as an outcome reported a decreased HR-QoL compared with the general 
population and a positive effect of prophylactic treatment (Royal, 2002; Fischer, 2003a; Fischer, 
2003b).  Although the World Health Organization (WHO) has advised the continuation of 
prophylactic treatment for life, its establishment has economic and practical hurdles.  The goals of 
an alternative approach are to reduce short-term disability and long-term joint damage and improve 
patients’ overall QoL and functional independence (Colvin, 2008).   
2.1.4.1 Factor VIII and Protein 
The human FVIII gene is located on the long arm of the X chromosome, at Xq28 (Poustka, 1991; 
Freije, 1992).  It spans 186 kb and consists of 26 exons separated by 25 introns (Gitschier, 1984; 
Toole, 1984). Most of the exons that make up the 9 kb mRNA are small (69-262 bp), with the 
exception of exon 14 (3.1kb) and exon 26 (1.9 kb), which primarily consists of the 3’ untranslated 
sequence. The resulting 7 kb coding sequence encodes a 2351 residue single chain precursor 
protein. Following cleavage of a 19 amino acid signal peptide, the mature 2332 amino acid protein 
is produced, which has a domain structure of A1-A2-B-A3-C1-C2.  The 3 homologous A domains 
bind Ca+2 and are essential for FVIII catalytic cofactor activity (Tagliavacca, 1997). There are 
short acidic sequences (a1, a2, a3) between A1 and A2 and at the A2-B and B-A3 junctions, 
respectively.  These regions are close to important proteolytic cleavage sites, contain tyrosine 
residues that are sulfated, and may affect the interaction of FVIII with other components of the 
coagulation pathway (Mumford, 2002; Pittman, 1992). The large central B domain is encoded by 
exon 14, is heavily glycosylated and is not necessary for activity (Pittman, 1993; Eaton, 1986). 
The acidic region (a3) that follows the B domain contains a major von Willebrand factor (VWF) 
binding site (Foster, 1988), and the two C domains are responsible for FVIII binding to 
phospholipids (Arai, 1989).  
Single chain FVIII is proteolytically processed to generate a heavy chain that is composed of 
domains A1-A2-B and a light chain, composed of domains A3-C1-C2.  These chains circulate in 
an inactive state bound to VWF as a heterodimer. Activation of FVIII occurs following thrombin 
cleavages between domains A1-A2 and A2-B, resulting in release of the B domain and the 
formation of a heterotrimer containing the A1, A2 and A3-C1-C2 domains.  

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The full length FVIII protein is encoded by a 7 kb DNA sequence, which exceeds the packaging 
limit of an AAV vector (~4.7kb). However, since the B-domain is not required for FVIII activity 
(Toole, 1986), the
 
 
 which produces a B-domain-deleted, but active FVIII protein. Many B-
domain-deleted FVIII variants have been constructed, but the derivative the Sponsor has chosen 
to produce from an rAAV vector is called FVIII-SQ (Lind, 1995). The FVIII-SQ gene produces a 
single chain translation product, which is cleaved efficiently into an A1-A2 heavy chain and an 
A3-C1-C2 light chain. This protein is a commercially available product, under the name Xyntha®, 
and has been used successfully to control and prevent bleeding episodes in individuals with 
hemophilia A.  Thus, expression of FVIII-SQ from a rAAV vector is expected to have the same 
safety and efficacy profile as Xyntha®. 
The natural site for the biosynthesis of FVIII has been the subject of debate for decades. Although 
it has been clear that liver cells contribute significantly to circulating FVIII levels, since liver 
transplantation corrects FVIII levels in hemophilia patients (Bontempo, 1987), the specific cell 
type responsible for biosynthesis and secretion of the protein has been controversial. Early after 
isolation of the gene, it was thought that FVIII mRNA and protein were co-localized in hepatocytes 
(Wion, 1985; Zelechowska, 1984). However, based on improved cell separation and sorting 
techniques, it is now clear that liver sinusoidal endothelial cells (LSECs) are the natural site of 
FVIII biosynthesis (Shahani, 2014). At the present time, no rAAV vectors that efficiently target 
LSECs are available. Therefore, 
 is 
being used, and transduction using this serotype leads to high levels of FVIII expression and 
secretion.  
2.1.4.2 Biology of Adeno-Associated Virus (AAV) Vectors 
Adeno-associated virus is a non-enveloped, replication-defective parvovirus that has not been 
associated with human disease.  AAV vectors are derived from the parent virus by removing all of 
the viral elements except for the inverted terminal repeats (ITR) and inserting the gene or genes of 
interest and their associated regulatory elements (Samulski, 1982; Samulski, 1987). The long-term 
safety of these vectors in humans is unknown; however, AAV vectors have been delivered to 
hundreds of human participants, in trials for cystic fibrosis, rheumatoid arthritis, inherited retinal 
degeneration due to autosomal-recessive retinal pigment epithelium 65 (RPE65) gene mutations, 
α1-antitrypsin deficiency, as well as hemophilia, and have been remarkably free of vector-related 
adverse events (Mingozzi, 2011a; Mingozzi, 2013a). Thus, AAV vectors are one of the most 
efficient in vivo gene delivery platforms.  In October 2012, the European Commission granted 
marketing authorization for Glybera® under exceptional circumstances as a treatment for adult 
patients diagnosed with familial lipoprotein lipase deficiency (LPLD) confirmed by genetic testing 
and suffering from severe or multiple pancreatitis attacks despite dietary fat restrictions.  This is 
the first AAV-based vector product granted marketing authorization in an International Conference 
on Harmonisation (ICH) region. 
AAV vectors do not require actively dividing target cells to achieve efficient transduction, as 
demonstrated in post-mitotic cells of brain, muscle, liver, and retina in vivo (Maguire, 2008; 
Maguire, 2009; Mingozzi, 2011b; Mingozzi, 2013b; Mingozzi, 2011a).  Also, at least in animal 
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studies, there is no immune response directed against the transduced cell, likely because all of the 
viral genes have been removed. This absence of immune response accounts, at least in part, for 
prolonged (months to years) transgene expression observed in animals following a single 
administration of an AAV vector.  Several groups have established that AAV efficiently transduces 
hepatocytes following a single administration via the portal vein, hepatic artery, or by the IV route, 
resulting in long-term (more than 10 years), dose-dependent transgene expression in large animals 
including dogs and NHPs (Snyder, 1997; Nakai, 1998; Xiao, 1998; Jiang, 2006; Niemeyer, 2009; 
Nathwani, 2011a). A memory CD8+ T cell response to AAV in humans would be expected to 
respond more efficiently to partially degraded AAV capsid peptides displayed on the cell surface 
of transduced hepatocytes in the context of major histocompatibility complex (MHC) Class I 
molecules (Manno, 2006). Indeed, studies document expansion of a population of AAV-capsid 
specific CD8+ T cells after AAV vector infusion into the hepatic artery in humans, whereas no 
such expansion is seen in animals receiving an AAV vector (Mingozzi, 2007).  Thus, humans’ 
previous exposure to wild-type AAV likely accounts for the differences between humans and all 
other species in immune response to capsid.  Although NHPs also have prior exposure to wild-
type AAV, they fail to mount recall T cell responses to AAV capsid antigens (Pañeda, 2009) in 
spite of readily detectable AAV capsid-specific T cells at baseline.  Ertl and colleagues have shown 
that AAV capsid-specific T cells from rhesus macaques show marked differences in function and 
differentiation status compared to those found in healthy human adults (Li, 2011), which may 
explain their differential reactivation by AAV vectors. 
2.1.4.3  Gene Therapy as an Alternative Approach 
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 intravenous catheters or 
frequent factor infusion, and improve participants’ overall QoL and functional independence 
(Colvin, 2008).  Preliminary results of a hemophilia B, sponsored by St. Jude Children’s Research 
Institute-University College London, demonstrated a reduction in the prophylactic use of factor 
replacement therapies in 10 participants who received gene transfer.  Additionally, at least 5 of 
these participants have reduced factor consumption by greater than 90% while remaining free of 
spontaneous bleeding episodes (Nathwani, 2011b; Nathwani, 2014).  
Several features make hemophilia A good model for gene therapy. The first advantage is that 
precise regulation of transgene expression is not required.  The therapeutic range is remarkably 
wide, from > 1% to 150% of normal.  It is clear, based on data from administration of FVIII 
products into patients with hemophilia A, that levels ≤150% are not associated with ill-effects 
since the protein circulates as a zymogen (inactive precursor).  Second, as stated, > 1% circulating 
FVIII 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 A 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, 

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naturally occurring canine models of the disease and genetically engineered hemophilic mice 
(Evans, 1989a; Evans, 1989b; Connelly, 1996; Bi, 1995; Lin, 1997). Finally, it should be noted 
that determination of therapeutic efficacy is straightforward and unequivocal in the case of 
hemophilia A, since plasma levels of FVIII are easy to measure and correlate well with clinical 
disease severity. 
2.2 
Rationale 
2.2.1 Description of SPK-8011 
SPK-8011 (also known as AAV-Spark200-BDD-hFVIII) is a rAAV vector composed of a bio-
engineered rAAV capsid (AAV-Spark200) and a codon-optimized expression cassette encodes the 
SQ variant of a B-domain-deleted human coagulation factor VIII (BDD-hFVIII) gene (Lind, 
1995). The full length FVIII protein is encoded by a 7 kb cDNA sequence, which exceeds the 
packaging limit of an AAV vector (~4.7kb).  Thus, the Sponsor has chosen a B-domain-deleted 
FVIII 
variant, namely FVIII-SQ (Lind, 1995), which directs the synthesis of a protein 
identical to a commercially available BDD-hFVIII protein, Xyntha®. 
 
A number of measures have been taken to improve the expression and safety of the transgene 
product compared with the previous vector iterations tested by the Sponsor or by others (Figure 
3). 
a) Capsid: 
• Utilizes AAV-Spark200, which is a novel bio-engineered capsid derived by 
 
 
(Azuma, 2007)   
b) Cassette: 
• Encodes the SQ variant of B-domain deleted hFVIII (Lind, 1995) and is codon-
optimized
 
 
 
 
(Levitt, 1989) 
 
It has been previously demonstrated that excess empty capsids may adsorb low-level neutralizing 
antibodies and non-neutralizing antibodies, permitting liver transduction after peripheral vector 
infusion even in their presence (Mingozzi, 2013b). This may be particularly important at lower 
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vector doses.  This hypothesis is consistent with clinical data from previous hemophilia B gene 
therapy trials in which the presence of empty capsids in the formulation correlated with higher 
expression levels at low vector doses (Monahan, 2015; Nathwani, 2014). For this reason, the final 
formulation of SPK-8011 may contain a mixture of empty and full capsid particles.   
SPK-8011 is manufactured according to good manufacturing practices (GMP) guidelines and will 
be administered to male individuals with severe hemophilia A (Section 5.1). 
2.2.2 Summary of Non-Clinical Experience with SPK-8011 
SPK-8011 contains a bio-engineered rAAV capsid (AAV-Spark200) that has been selected for 
efficient transduction of human hepatocytes and de-selected for transduction of murine 
hepatocytes, creating a challenge for safety and efficacy testing in mice.  An additional challenge 
is the generation of antibodies against hFVIII in all immunocompetent animals. Thus, the non-
clinical pharmacology and toxicology studies utilized 1 species (NHP) to evaluate the safety of the 
AAV-Spark200 capsid and immunodeficient mice to evaluate the safety of sustained expression 
of hFVIII.  The murine studies relied on another capsid, rAAV-Spark100, to achieve efficient 
transduction of mouse hepatocytes with the hFVIII transgene. 
A study to evaluate the safety of AAV-Spark200 and short-term expression of hFVIII was 
conducted in cynomolgus macaques. Three cohorts of animals (n=3) were treated with increasing 
doses of SPK-8011 (2x1012, 6x1012, and 2x1013 vg/kg). Animals were monitored for clinical 
observations, body weights clinical pathology (clinical chemistry, hematology, coagulation, 
urinalysis) over the course of 60 days. In addition, hFVIII antigen levels, FVIII inhibitory 
antibodies and D-dimer levels were assessed throughout the study. Average hFVIII antigen levels 
peaked around Weeks 2-3 with 22.3 ± 6.2% hFVIII seen at the low dose, 61.6 ±15.7% at the mid 
dose and 153 ± 58.1% at the high dose, demonstrating efficient transduction of NHP hepatocytes 
with this novel AAV serotype. As predicted, the hFVIII levels began to decline around Week 4 in 
most animals, which correlated with an increase in anti-hFVIII antibodies. In most animals, the 
antibodies were inhibitory in nature, with some NHPs having inhibitory antibodies with titers as 
 Total FVIII activity levels also decreased in these animals. The 
generation of anti-FVIII antibodies has also been observed by others following hepatic AAV-
hFVIII gene transfer in NHPs (McIntosh, 2013). No evidence of thrombosis, as measured by D-
dimer levels, was observed, even when hFVIII levels as high 
 of normal were observed.  
Preliminary information on the biodistribution of the 
 capsid in NHPs 
demonstrates that the
 
  A separate study designed to evaluate the potential for 
germline transmission of the 
 capsid was performed in rabbits using a vector 
encoding the hFIX transgene.  The 
 capsid showed very limited distribution to 
semen, even at doses as high as 1x1013 vg/kg. This pattern differs from other vectors investigated 
including 
, potentially making this rAAV capsid safer, in terms 
of genotoxicity, than the others. 
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2.2.3 Summary of Clinical Experience with SPK-8011 
Study SPK-8011-101 is the first study to administer SPK-8011 in humans; however, rAAV vectors 
have been administered to humans in more than 100 gene therapy clinical trials for a wide range 
of indications, including multiple studies in hemophilia A and B (George, 2017; High, 2011; 
Rangarajan, 2017; Miesbach, 2016; Nathwani, 2014; Nathwani, 2011b; Manno, 2006; Monahan, 
2015; Mingozzi, 2011a). 
Based on early experience with SPK-8011 in this study, as well as other AAV-mediated gene 
transfer trials for hemophilia A and B, the following preliminary observations can be made:  
• In general, AAV-mediated gene therapy continues to demonstrate an acceptable safety 
profile.  
• AAV-based strategies for hemophilia have resulted in sustained expression of clotting 
factor at levels sufficient to reduce or eliminate the need for clotting factor infusions after 
a single IV infusion. 
• Neutralizing antibodies against FVIII or FIX have not been reported for any participant to 
date. 
• Liver-directed AAV-mediated gene transfer may result in development of an apparent 
dose-dependent immune response to the vector capsid, as evidenced by a transient and 
asymptomatic rise in transaminases (ALT and/or AST) and  a decline in factor  level This 
response can potentially lead to immune-mediated clearance of vector-transduced 
hepatocytes and an eventual loss of transgene expression.  
• At the lower doses infused, the transient elevation of transaminases is typically attenuated 
by a tapering course of corticosteroid therapy to prevent loss of AAV-transduced 
hepatocytes. 
At 
higher 
doses, 
some 
participants 
have 
required 
additional 
immunomodulation to control the immune response during the corticosteroid taper; other 
participants have lost all expression despite initiation of reactive steroids at the first sign 
of elevation or upward trend of ALT with or without coincident unexpected decline in 
FVIII expression. 
• Early initiation of prophylactic corticosteroids in the higher dose (2x1012 vg/kg) resulted 
in a transient supraphysiologic increase in local FVIII levels to greater than 200%.  An 
intermediate dose cohort (1.5x1012 vg/kg) was therefore initiated.  The mechanism of 
action for the FVIII increase has been examined in a nonclinical study in mice where the 
administration of prednisolone in combination with SPK-8005 (which contain the same 
transgene and regulatory elements as SPK-8011 encapsidated in a capsid 
 
) transiently increased mean human FVIII expression 1.5- to 3.2-fold 
compared with animals treated with SPK-8005 alone. 
• The attempt to use oral corticosteroids 
 
, though successful in achieving long-term expression of FVIII associated with 
hemostatic control, also resulted in the need for prolonged courses of corticosteroids, 
resulting in undesirable steroid-associated side effects. In some cases, it was difficult to 
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taper off steroids except by adding another immune suppressive agent. For this reason, 
prophylactic steroids will no longer be pursued.  
Although the early results are promising, additional investigation is needed to determine whether 
there is a transient immunosuppressive regimen that will reliably control immune responses in all 
patients and allow long-term expression of the donated gene.  Based on prior clinical studies, non-
clinical studies summarized below, and input from clinical experts in rheumatology, organ 
transplantation, viral immunology, and bone marrow transplantation, the 2 regimens shown in 
Figure 1 will be evaluated. These represent 2 distinct approaches to the problem of a CD8+ T cell 
response to the AAV capsid.
 
 
 
 
 
 
 
 
  
2.2.4 Summary of Non-clinical Experience with Tocilizumab 
In order to test whether blockade of IL-6 receptor signaling with the humanized monoclonal 
antibody, TCZ (Actemra®) could decrease immune response in the context of AAV-mediated gene 
delivery, 
a 
non- 
good 
laboratory 
practice 
(GLP) 
study 
in 
NHPs 
(Study# 
IMM_PC2019_001/Covance 8400655) was performed. One of the aims of the study was to rule 
out the possibility of IL-6 blockade increasing the percent of animals developing anti-transgene 
antibodies, as observed with other immunosuppressive drugs (Mingozzi, 2007). However, since 
virtually all NHP will develop neutralizing antibodies against human FVIII following gene transfer 
(McIntosh, 2013), this assessment would be precluded if a FVIII cassette were used. To this end, 
FIX was selected as the transgene of choice, as only approximately one third of NHPs develop 
antibodies against AAV-derived human FIX. An AAV vector serotype, 
, was used 
to express the human coagulation factor IX (hFIX) transgene in the livers of healthy male 
cynomolgus macaques under the control of a liver-specific promoter. Ten 
 
animals were divided into 2 experimental groups (n=5/group). One of the groups received an IV 
 1 day prior to vector infusion. 
 
 The next day, both 
groups received an IV infusion of 
.  
No animals demonstrated hypersensitivity or anaphylactic reactions following administration of 
either TCZ or 
.  Animals were bled every week for analysis of safety 
endpoints and hFIX transgene expression levels, along with monitoring of circulating IL-6 levels. 
The study had a follow up duration of 13 weeks post-vector infusion. All animals survived to their 
scheduled sacrifice.  The development of subacute decreases in neutrophil counts following single 
dose TCZ has been observed in human healthy volunteers; no animals in this study developed 
neutropenia or thrombocytopenia below baseline. Two of 5 animals developed isolated transient 
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elevations of liver transaminases (< 2 x upper limit of normal (ULN)) which resolved without 
intervention without evidence of hepatic obstructive disease (hyperbilirubinemia) or hepatic 
insufficiency. Importantly, clinical and anatomic pathology examination of the liver and a panel of 
40 organs and tissues showed no macroscopic or microscopic findings in animals receiving the 
 vector alone or in combination with TCZ. Hepatic transduction as assessed 
by vector genome copy number in liver (at sacrifice) and by circulating hFIX antigen levels (weekly 
throughout the study) was not significantly different in the animals that received TCZ compared to 
controls. 
IL-6, and in general innate immunity driven by the AAV capsid (Hösel, 2012; Kuranda, 2018) and 
DNA payload (Martino, 2011; Rogers, 2017), are key triggers of AAV vector immunogenicity 
including adaptive humoral and cellular responses.  
 
 
 Importantly, TCZ administration was well tolerated and did not 
seem to affect hepatic transduction. 
 
In control animals, associated IgG and neutralizing 
antibody titers against the capsid developed at markedly elevated levels and persisted through the 
duration of the study. 
 
 
 
In regards to cellular immune responses, prior studies performed using human CD8+ and CD4+ T 
lymphocytes identify TNFα as one of the main cytokine signatures of T cell activation in response 
to AAV (Kuranda, 2018). Peripheral blood mononuclear cells (PBMC) from control animals and 
the TCZ group were isolated and subsequently re-stimulated in vitro with the 
 
vector. At all timepoints (Days 28-84), the mean number of PBMCs secreting TNFα were lower in 
the TCZ-treated animals compared to controls. The observations in PBMCs were correlated with 
those from livers which showed that TCZ treatment promoted a long-lasting anti-inflammatory 
milieu in the liver. Increased secretion of the anti-inflammatory cytokine IL-10 was observed in 
mixed liver cell culture from TCZ-treated animals, but was not measurable in cultures from animals 
that received 
 vector alone. Further, immunophenotyping of cell surface 
major histocompatibility complex (MHC) class II expression on liver sinusoidal endothelial cells 
from TCZ-treated animals was consistent with expression of a more tolerogenic phenotype. 
These preclinical studies indicating the potential for IL-6 receptor blockade to modulate AAV 
vector immunogenicity are of interest in light of observations in a trial of AAV vector mediated 
gene transfer for hemophilia B, in which initial transgene FIX expression was achieved and then 
lost in all participants except for 1, who instead has sustained FIX correction for > 3 years. Whole 
exome sequencing of all participants demonstrated that the single participant who avoided apparent 
immune-mediated loss of transgene expression carried a functional polymorphism in the IL-6 
Receptor gene, predicted to result in diminished IL-6-mediated pro-inflammatory signaling (Bilic, 
2019). Altogether, these data support the use of TCZ in participants receiving AAV-based gene 
therapy treatment as a safe and potentially effective strategy to modulate vector immunogenicity. 
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2.2.5 
Summary of Non-Clinical and Clinical Experience with Mycophenolate Mofetil 
Pre-clinical studies of hepatic artery administration of AAV8-hAAT-hFIX16 were performed in 
rhesus macaques; in these studies, vector was given alone or together with a short course of 
immunomodulation to assess the potential safety and efficacy of the approach. The 
immunomodulation regimen included tacrolimus (FK506) and MMF. The hFIX transgene 
expression cassette used in this study was the same as initially used in IND 9398 and contained 
the wild type copy of the hFIX cDNA. 
Results have been published (Jiang, 2006) demonstrating that administration of AAV8-hAAT-
hFIX16 was safe and effective in 5 out of 6 monkeys at a dose of 5x1012 vg/kg, provided there were 
low or undetectable levels of pre-existing AAV8 neutralizing antibody (NAb). Co-administration 
of MMF and FK506 with AAV8 vectors was safe and did not alter the efficiency of liver 
transduction in NHPs. 
The regimen of FK506 and MMF has also been used successfully in treating patients who undergo 
liver transplantation to prevent graft rejection (Post, 2005; Perry, 2005). MMF has been 
administered along with rapamycin to a single participant who received AAV2-hFIX16 under IND 
9398. The side effect profile was acceptable and there were no serious adverse events (SAEs) on 
this regimen. The side effects of immunomodulatory drugs are well described (Post, 2005; Perry, 
2005) and include the risk of hepatitis virus reactivation (Savas, 2007; Melon, 2005; Lalazar, 2007; 
Francisci, 2006; Calabrese, 2006) and the occurrence of B cell lymphoproliferative disorders 
(Gross, 1999; Pascual, 2007; Bakker, 2007). Long-term follow-up data are not available on another 
participant who received a 16-week course of MMF and rapamycin; this participant died 
approximately 2.5 years later of bleeding complications related to hemophilia. 
MMF has been used to treat individuals with congenital hemophilia A and hemophilia B as well as 
acquired hemophilia A for periods of months as part of combined immune suppression approaches 
for the eradication of inhibitor antibodies. In these case series, infections have been the most 
common complication with incidence similar to that described with the use of MMF in 
rheumatologic conditions. Transient neutropenia has also been reported, although attribution to 
MMF when used in combined drug regimens is not clear from these reports. No transaminase 
elevations and no exacerbation of underlying hemophilic bleeding are reported in these series.  
2.3 
Benefit/Risk Assessment 
2.3.1 Risk Assessment 
The following are potential risks with the administration of any rAAV gene therapy for hemophilia 
and will be monitored for in this study.  Participants should be advised to notify the Investigator(s) 
immediately and/or seek immediate emergency care, depending on the severity of the reaction, if 
any symptoms occur. 
2.3.1.1 Allergic Reaction or Anaphylaxis 
As of 24 November 2020, there has been 1 report of symptoms associated with SPK-8011 (rAAV-
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Vomiting, pyrexia, low back pain, and myalgia were reported in 1 participant; events started to 
resolve within 12 hours (per investigator), all completely resolved in 1 to 3 days with 
acetaminophen (High, 2018).  Allergic-type reactions, including anaphylaxis, have been reported 
for all rFVIII protein products.  These events are rare and have occurred in close temporal relation 
with the development of FVIII inhibitors.  Participants should be informed of early symptoms and 
signs of hypersensitivity reactions, including hives, generalized urticaria, angioedema, chest 
tightness, dyspnea, wheezing, faintness, hypotension, tachycardia, and anaphylaxis.  If such an 
event occurs, the participant should be instructed to seek immediate medical care. 
2.3.1.2 Inhibitor Development 
Inhibitor development most often occurs within the first 20 infusions of FVIII replacement 
therapies. There is a possibility that participants infused with SPK-8011 will develop inhibitors to 
FVIII, although inhibitor development has not occurred in any of the participants who have 
received AAV2-hFIX, AAV8-hFIX (Nathwani, 2014), AAV8-hFIX19 (under investigational new 
drug application (IND) 15149), BAX-335 (under National Clinical Trial (NCT)# 01687608).  In 
addition, as of 24 November 2020, inhibitor development has not been reported in any of the 17 
participants in this study. Moreover, no inhibitors have been reported in the recent BioMarin trial 
of an AAV5-BDD-hFVIII (BMN-270) (Rangarajan, 2017; Pasi, 2020) nor in ongoing Study SPK-
8016-101 as of 26 October 2020.   The likelihood of participants in this study developing inhibitors 
will be minimized by including only individuals who do not make inhibitor antibody to FVIII, 
despite prior heavy exposure to the FVIII infused protein (i.e., those who have had greater than 
150 EDs to FVIII concentrates).  Samples will be taken at regular intervals to monitor for inhibitor 
formation during the study and archives will be maintained for possible future analysis should 
inhibitor development occur. 
2.3.1.3 Elevation of Hepatic Transaminases 
As of 24 November 2020, of the 17 enrolled participants, 5 of them (29%) experienced treatment-
emergent adverse events (TEAEs) reported as transaminases or alanine transaminase (ALT) 
increase, with severity ranging from mild to moderate in the higher dose groups (2 in the 1.5x1012 
vg/kg dose cohort, and 3 in the 2x1012 vg/kg dose cohort); 1 of the events in the 2x1012 vg/kg dose 
was reported as a SAE.  The cause of a transient and asymptomatic hepatic transaminase elevation 
(i.e., elevated alanine aminotransferase and/or aspartate aminotransferase) observed in earlier 
liver-directed AAV-mediated gene transfer clinical trials has not been established.   However, 
some individuals have developed dose-dependent T cell responses to AAV capsids, in the context 
of elevation in transaminases, and the presumptive mechanism is a memory CD8+ T cell response 
to peptides derived from the AAV capsid of the vector (Mingozzi, 2007).  Transaminase elevation 
(progressive elevation of hepatic transaminases of approximately 1.5- to 2.0-fold above 
screening/baseline accompanied with the loss of transgenic FVIII activity levels should it occur, 
will be managed in this study with immunosuppressive therapies in tapering dose schedules.  In 
the setting of AAV-FIX, corticosteroids have generally been effective for the hepatic transaminase 
elevations observed in the context of AAV vector infusion to the liver (Nathwani, 2014); at the 
higher doses required for AAV-FVIII, this has not always been the case. 

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2.3.1.4 Anti-AAV Neutralizing Antibody Development 
As is expected after systemic administration of AAV vectors, all 17 participants (100%) treated 
with SPK-8011 developed neutralizing antibodies to the AAV capsid. This risk seems to have no 
immediate impact on the expression of FVIII from the current AAV gene therapy, but development 
of neutralizing antibodies to AAV could potentially preclude the chance of a participant receiving 
another AAV gene therapy in the future. 
2.3.1.5 Bleeding Episodes 
The proposed doses levels of SPK-8011 may not be sufficient to raise the vector-derived FVIII:C 
levels to a therapeutic level for control and prevention of bleeding episodes when the participants 
halt their prophylaxis (factor or non-factor replacement) treatment after vector administration.  
Clinical experience suggests most patients can stop routine prophylaxis within 2 weeks of 
receiving SPK-8011.  Participants will be advised to treat their bleeding events with their usual 
FVIII products during the follow-up observation period.  Although bleeding (the nature of the 
disease) is not considered an adverse event, participants will record the dates of bleeding events, 
the type and location of the bleed, and the FVIII product and dosage used to treat the bleeding 
episode in the Infusion Log (Appendix 13.1). 
2.3.1.6 Possible Side Effects from Corticosteroids 
To mitigate the potential for harm due to cytotoxic T-lymphocyte (CTL) response against the 
capsid and to maintain endogenous FVIII expression, corticosteroids are allowed in the current 
protocol for participants who develop elevated transaminases, and declining FVIII activity.  
Corticosteroids for the interruption of autoimmune-mediated inflammation most commonly have 
been given as daily oral therapy (e.g., prednisone or prednisolone) or as 
 of intravenously 
dosed methylprednisolone (Gordon, 2018).  
Participants with elevated hepatic transaminases will be monitored closely to minimize the risk of 
side effects, to utilize the lowest effective dose and to shorten the duration of the corticosteroid 
therapies by tapering as soon as there is evidence of resolution of hepatic transaminase elevation. 
While on corticosteroids, participants will also be monitored for side effects including 
opportunistic infections.   
Corticosteroids such as methylprednisolone, prednisolone, and prednisone have a number of well-
described side effects including: hypertension, edema and swelling, tachycardia, congestive 
cardiac insufficiency, alterations in serum electrolytes, hyperglycemia, pain, increased blood urea 
nitrogen (BUN) and creatinine, osteoporosis and avascular necrosis of bone, decreased resistance 
to infection, cataract development, dizziness, trembling, emotional instability, insomnia, nausea, 
vomiting, weight gain, and elevated intraocular pressure.  
As of 24 November 2020, of the 17 enrolled participants in Study SPK-8011-101, 3 of them 
(Participants 5, 15, and 16) experienced adverse events (AEs) presumed to be related to 
immunomodulatory therapy (e.g., adrenal insufficiency, gastroesophageal reflux disease, 
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osteoporosis, irritability, weight gain, generalized edema, acne, hypomagnesemia, hot flashes, and 
hyperactivity). In addition, as of 26 October 2020, steroid-associated and nonserious AEs (e.g., 
cushingoid appearance, candida infection, swelling face, tooth infection, increased blood glucose, 
and fatigue) have been reported due to excessive long-term use of corticosteroids in 3 of the 4 
participants in a similar hemophilia A gene therapy study (SPK-8016-101) initiated by the 
Sponsor. 
Populations at special risk for side effects from prolonged and/or high dose corticosteroid use 
include individuals with pre-existent osteoporosis (in particular, vertebral osteoporosis), brittle 
diabetes, labile hypertension, obesity, and emotional instability. The use of alternative or combined 
immune modulating agents may allow lower exposure to corticosteroids (also discussed below in 
Section 2.3.1.7). 
The planned prophylactic regimens of TCZ and MMF in future enrolled participants are aimed to 
reduce the need for corticosteroids to avoid these side effects. 
2.3.1.7 Risks Associated with Additional Immune Modulating Agents 
The potential side effects of corticosteroids all occur with greater prevalence as treatment is 
prolonged. For this reason, inflammatory conditions that respond to corticosteroid monotherapy 
are frequently treated instead with combined immune modulating agents to achieve anti-
inflammatory efficacy while limiting the quantity and/or duration of corticosteroid exposure. An 
example of such “steroid-sparing approach” that has been clinically validated is provided in the 
guidelines for the treatment of autoimmune hepatitis recommended by the American Association 
for the Study of Liver Disease (AASLD) and by the European Association for the Study of the 
Liver (EASL).  Both the AASLD and the EASL provide recommendations for the dosing of oral 
azathioprine in addition to prednisone/prednisolone therapy to provide therapeutic benefit while 
using lower steroid doses and/or to achieve successful taper off corticosteroids. Additional immune 
modulating agents, including tacrolimus and MMF, have been used to overcome suboptimal 
response to corticosteroid monotherapy or corticosteroid/azathioprine combined therapy in the 
setting of immune-mediated hepatic inflammation. Participants who are treated with azathioprine, 
tacrolimus, or other immune suppressive agents will be monitored closely as described above 
(Section 2.3.1.6) for side effects and to allow use of the lowest dose and shortest course of immune 
modulating agents.  
Use of any of these drugs with AAV, concomitant medications and/or other immunomodulatory 
drugs may increase the risk of hepatotoxicity.   
Use of any immunosuppressants may increase the risk of infection. This may include community 
acquired viruses such as influenza and COVID-19, as well as opportunistic infections.  
Immunosuppressive therapy may enhance adverse/toxic effects of live vaccines and may diminish 
the protective effect of vaccines. Due to the potential that trial participants may receive an 
immunosuppressive medication during the SPK-8011-101 trial, it is suggested that the investigator 

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and participant review and complete all age-appropriate vaccinations during the screening period 
and at least 4 weeks prior to planned day of administration of SPK-8011.  If a participant is 
currently receiving immunosuppressive medication, timing of vaccinations could be adjusted 
around the participant’s course of immune suppressant treatment. 
2.3.1.7.1 
Azathioprine 
Azathioprine is an immunosuppressive purine antimetabolite. Side effects from azathioprine may 
include cytopenias (in particular, bone marrow suppression leading to neutropenia and 
thrombocytopenia), nausea, vomiting, diarrhea, rash, fever, and arthralgia. Hepatotoxicity, 
presenting as liver transaminase elevations (may be idiopathic or associated with cholestatic 
hepatitis) with or without abdominal complaints, is uncommonly observed, however the risk is 
increased in association with chronic liver disease.  
As of 24 November 2020, in this ongoing SPK-8011-101 gene therapy study, 1 participant was 
prescribed azathioprine, used to aid in the taper from prednisone, 
 
. As of 26 October 2020, in a similar hemophilia A gene 
therapy study (SPK-8016-101) initiated by the Sponsor, 2 participants received azathioprine 
during the taper off corticosteroids.  One participant experienced azathioprine-induced nonserious 
hepatotoxicity which was characterized by transient increases of alanine aminotransferase (ALT) 
(2.3 x ULN), aspartate aminotransferase (AST) (2 x ULN), gamma-glutamyl transferase (GGT) (6 
x ULN), and lactate dehydrogenase (LDH) (1.2 x ULN), occurring within 1 week of escalating 
from a dose of 
.  Enzyme levels returned to normal 10 days after 
azathioprine was stopped.  A second individual on the SPK-8016-101 trial was prescribed 
 as an aid to taper and discontinue prednisone, 
without transaminitis or other adverse effects. 
Populations at special risk for side effects from azathioprine therapy include patients with very 
low thiopurine methyltransferase (TPMT) activity. Patients with near-zero erythrocyte 
concentrations of TPMT activity are at risk for myelosuppression during azathioprine treatment 
(Manns, 2010).  Only 0.3%-0.5% of the population has a severe enzyme deficiency, and not all 
patients with a deficiency of this degree experience bone marrow failure. Individuals will be tested 
at screening for SPK-8011 gene therapy for TPMT deficiency prior to initiation of azathioprine 
dosing. Chronic immunosuppression with azathioprine increases the risk of malignancy so 
azathioprine should be used with caution in individuals with malignancy.  
2.3.1.7.2 
Tacrolimus 
Tacrolimus is an immunosuppressive calcineurin inhibitor that interferes with several calcium-
dependent processes in immune cells. The most common adverse reactions to tacrolimus include 
abnormal renal function, hypertension, diabetes mellitus, fever, tremor, paresthesias, 
hyperglycemia, cytopenia (leukopenia, anemia), abdominal complaints, electrolyte abnormalities 
(hyperkalemia, hypomagnesemia) and hyperlipemia. More severe neurotoxicity is described at 
higher whole blood trough concentrations and therapeutic drug monitoring is required in the trial. 
As with other immune suppressive agents, chronic use is associated with increased risk of infection 
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and malignancy, in particular lymphoma and skin cancer. Tacrolimus should be used with 
supervision by a physician with experience in immunosuppressive therapy. Tacrolimus may 
induce changes in blood concentrations of, and also be affected by use of, concomitant 
medications, and potential drug-drug interactions with tacrolimus must be considered during 
therapy (Manns, 2010).  
As of 24 November 2020, in this ongoing SPK-8011-101 gene therapy study, 2 participants have 
been prescribed tacrolimus, used to aid in the taper from prednisone.  
 
.  One participant was prescribed tacrolimus 
 during the 
prednisolone taper.  The tacrolimus dose required frequent monitoring and adjustment due to 
apparent pharmacokinetic interactions between tacrolimus and the participant’s concomitant use 
of highly active anti-retroviral therapy (HAART).  The addition of tacrolimus allowed wean from 
all immune suppressive therapy without recurrence of hepatic inflammation and the participant 
sustains a current FVIII level of 15%.  The immunosuppressive taper of a second participant used 
co-therapy with prednisone and tacrolimus 
. Mild elevations of the serum creatinine 
have been observed in the local laboratory and have corrected with adjustment of the tacrolimus 
dose. During the prednisone and tacrolimus taper, the FVIII level declined and MMF was added 
to the immunomodulation regimen. MMF and tacrolimus were used concomitantly 
 
without AE.  
2.3.1.7.3 
Tocilizumab 
TCZ is a humanized monoclonal IgG antibody that binds to and interferes with the function of 
both soluble and membrane-bound interleukin-6 receptors. The following side effects have been 
reported in patients taking TCZ: upper respiratory tract infection, nasopharyngitis, headache, 
hypertension, dizziness, bronchitis, rash, mouth ulceration, abdominal pain, gastritis, transaminase 
increased, circulating neutrophil count decreased, and hypercholesterolemia. Side effects 
associated with a single dose or short courses of TCZ include hypersensitivity/anaphylaxis, 
neutropenia, thrombocytopenia, hypofibrinogenemia, and hepatotoxicity including transaminase 
elevations.  Increases in the transaminases have been reported days to months following an 
infusion of TCZ (National Institute of Diabetes and Digestive and Kidney Diseases, 2015).  Rare 
cases of liver failure have been ascribed to TCZ, however these have occurred with chronic 
administration in the setting of rheumatoid arthritis. The effect on ALT of 1 or 2 doses of IV TCZ 
has been reported in adults with rheumatoid arthritis (Emery, 2019). A median increase of 10-15 
U/L was observed within 2-4 weeks of 1-2 doses of 4 mg/kg or 8 mg/kg IV TCZ. Elevations to > 
3 x ULN were demonstrated in 0 out of 25 individuals who received a single dose of 4 mg/kg IV 
and 2 out of 24 participants who received a single dose of 8 mg/kg IV. Of note, these study 
participants were also treated concomitantly with methotrexate, a potentially hepatotoxic drug. 
Transaminitis generally resolved within weeks of discontinuing TCZ dosing. 
In this trial of SPK-8011, individuals in cohort 2 will receive TCZ. Elevations of ALT that occur 
within 
 following gene delivery, if seen, will likely result from TCZ exposure.  
Elevations of ALT that occur later than 6 weeks following gene therapy 
 
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 will be possibly or probably the result of cellular immune response directed against 
AAV-transduced hepatocyte, in particular if observed with coincident decrease in the circulating 
transgenic FVIII activity.  
Anaphylaxis that required treatment discontinuation has been reported in 0.1-0.9% of patients 
using repeated doses of TCZ for the treatment of a variety of autoimmune diseases (Actemra® 
Prescribing Information, 2020).  Anaphylaxis most commonly does not occur with the first 
exposure but instead with the second to fourth exposure to TCZ.  Neutropenia has been observed 
following treatment with TCZ.  Most typically, absolute neutrophil counts decreased to the nadir 
3 to 5 days following TCZ administration and thereafter, neutrophils recovered towards baseline 
in a dose dependent manner.  Thrombocytopenia has been observed following treatment with TCZ.   
Elevations in lipid parameters (total cholesterol, LDL, HDL, triglycerides) have been reported at 
6 weeks following initiation of TCZ.  Elevated lipids may be managed with lipid lowering agents. 
Clinically, participants will be monitored closely for neutropenia and evidence of opportunistic 
infections while they are on TCZ.  Serious infections leading to hospitalization or death including 
tuberculosis (TB), bacterial, invasive fungal, viral, and other opportunistic infections have 
occurred in patients receiving TCZ. The most common serious adverse reactions associated with 
long-term repeated dosing of TCZ are infections, including serious and opportunistic infections, 
with the incidence of infection associated with the length of the course of TCZ.  With respect to 
this point, it should be noted that the contemplated course of TCZ therapy in this protocol is much 
shorter (from 1 to 2 doses) than the regimens used in more typical indications, requiring long term 
immunomodulation. In the setting of prolonged administration, activation of latent tuberculosis 
has been observed.  The incidence of tuberculosis in worldwide clinical development programs is 
0.1%.  Participants will be screened for latent tuberculosis and excluded from the TCZ arm if latent 
or active tuberculosis is observed.  Cases of herpes zoster exacerbation have been reported. The 
impact of treatment with TCZ on the development of malignancies is not known but malignancies 
were observed in clinical studies.  TCZ is an immunosuppressant, and treatment with 
immunosuppressants may result in an increased risk of malignancies. For a detailed description of 
the risks associated with TCZ, please see Actemra® US Prescribing Information (2020).  
2.3.1.7.4 
Mycophenolate Mofetil 
Mycophenolate mofetil is an antimetabolite immunosuppressant. The following AEs have 
occurred in patients receiving MMF: hypertension, edema, low blood cell counts, pain, diarrhea, 
nausea, vomiting, increased cholesterol and increased risk of infection. Clinically, participants will 
be monitored closely for neutropenia and evidence of opportunistic infections while they are on 
MMF. Investigators will be sensitive to gastrointestinal complaints from the participants while 
they are on MMF. 
Patients receiving immunosuppressive regimens involving combination drugs, including MMF, 
are at increased risk of developing lymphomas and other malignancies, particularly of the skin. 
The risk appears to be related to the intensity and duration of immunosuppression rather than to 
the use of any specific agent. Lymphoproliferative disease or lymphoma developed in 0.4% to 1% 
of patients receiving 
 in controlled clinical 
trials of renal, cardiac, and hepatic transplant patients (CellCept US Prescribing Information, 
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2019). Again, it should be noted that these findings were seen in individuals receiving long-term 
treatment with MMF.  
Cases of progressive multifocal leukoencephalopathy (PML), sometimes fatal, have been reported 
in patients treated with MMF. Hemiparesis, apathy, confusion, cognitive deficiencies and ataxia 
were the most frequent clinical features observed. The reported cases generally had risk factors for 
PML, including treatment with additional immunosuppressant therapies and impairment of 
immune function. MMF is usually taken for many years to prevent organ rejection after heart, 
liver, or kidney transplantation. However, the duration of MMF use in the context of this study 
will be much shorter (weeks to months), which mitigates the risk of developing serious side effects. 
For a detailed description of the risks associated with MMF, please see CellCept US Prescribing 
Information (2019).  
The risk of genotoxic effects on sperm cells cannot be excluded with the use of MMF. Thus, 
sexually active male patients and/or their female partners are recommended to use effective 
contraception during treatment of the male patient and for at least 90 days after cessation of 
treatment. 
As of 24 November 2020, in this gene therapy Study SPK-8011-101, 2 participants have been 
prescribed MMF to control an apparent immune response not controlled with prednisone alone.  
One participant was prescribed MMF after the concomitant use of tacrolimus and prednisone did 
not fully suppress an immune response. MMF was added 
, and MMF and 
tacrolimus were concomitantly administered for 
.  The participant remains on MMF as a 
stand-alone immunomodulator.  The other participant completed an immunosuppressive taper 
using co-therapy with prednisone and MMF. MMF has been administered for 
 with no 
AEs associated with MMF.  The addition of MMF allowed weaning from prednisone without 
recurrence of hepatic inflammation and the participant currently has a FVIII level of 4.0%. 
2.3.1.7.5 
Immune Suppressive Medications and Risk of Infections, including COVID-
19 Risk 
Immune suppressive medications including corticosteroids, TCZ, MMF, azathioprine and 
tacrolimus, used alone or in combination, may increase the risk of bacterial, mycobacterial, fungal 
and viral infection. This may include community acquired viruses such as influenza and COVID-
19 as well as opportunistic infections. Extensive information regarding the risk of contracting 
COVID-19 and the clinical course of COVID-19 for individuals taking immune suppressant 
medications and individuals with immune suppression is currently unknown (Guan, 2020; Richter, 
2016; Ni, 2019; Bello, 2012; Russell, 2020a; Russell, 2020b; Favalli, 2020). The chronic use of 
corticosteroids and biological immune suppressive agents has been associated with increased rates 
of influenza infection (an example of epidemic pneumonia), so increased vigilance regarding 
diagnosis is particularly important because symptoms of infection, including fever, may be masked 
by the medications (Favalli, 2020).  The clinical course of COVID-19 infection including 
morbidity and mortality for individuals taking immune suppressant medication is the subject of 
prospective investigation in clinical trials (Richter, 2016; Russell, 2020a; Russell, 2020b; Favalli, 
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2020). Corticosteroid use in the treatment of the Acute Respiratory Distress Syndrome (ARDS) of 
influenza has been associated with increased mortality and increased morbidity including 
secondary bacterial and fungal infections (Ni, 2019; Favalli, 2020; Russell, 2020a; Russell, 
2020b). Although corticosteroids were employed as a potential supportive therapy in the treatment 
of the ARDS associated with coronavirus outbreaks of SARS-CoV and Middle East respiratory 
syndrome-related coronavirus (MERS-CoV), clearance of the virus and steroid-associated 
complications resulted, without improved mortality. Several clinical trials are currently examining 
the potential therapeutic value of TCZ and other biological immune suppressive drugs in 
suppressing the cytokine release syndrome caused by SARS-CoV2 that drives ARDS, however, 
results are not yet available to guide current management (Russell, 2020a; Russell, 2020b).  
As additional clinical evidence accrues, it is advised to consider participants using immune 
suppressive medication in the SPK-8011 clinical trial program to be at increased risk of infection 
(clinically susceptible) including pneumonia infection with community acquired influenza and 
COVID-19. Increased vigilance for signs and symptoms consistent with a diagnosis of COVID-
19 is warranted because symptoms of infection, including fever, may be less clinically evident 
(Favalli, 2020) while taking immune suppressive medication. Careful clinical management should 
include instruction regarding COVID-19 preventive measures, e.g., social distancing and hand 
washing hygiene (Public Health England, 2020; National Health Service, 2020). Investigators 
along with their SPK-8011-101 clinical trial participants should consider individualized 
approaches to social/behavioral interactions as well as clinical visits and treatment approaches 
consistent with national, local and institutional COVID-19 prevention guidance (U.S. Food and 
Drug Administration, 2020).   
2.3.2 Potential Benefit 
The main purpose of this study is to evaluate the safety of SPK-8011 at up to 3 or 4 different dose 
levels.  It is not known if the dose levels will raise the activity levels of FVIII in humans, though 
based on prior clinical experience in hemophilia B and non-clinical experience in NHPs with SPK-
8011, it is hypothesized that the dose levels tested may result in detectable FVIII:C.  Current 
commercially available FVIII concentrates exhibit in vivo half-life (ranging from 10.8 to 19.7 
hours) which require IV injections of approximately every 2 to 3.5 days for an effective 
prophylactic treatment (National Hemophilia Foundation, 2016).  SPK-8011 has the potential to 
reduce the frequency of administration in the prevention of bleeding episodes. Additionally, 
important scientific insights about rAAV-mediated gene transfer for hemophilia are expected from 
the data generated in this proposed study. 
2.4 
Study Rationale 
Published data from Nathwani and colleagues (2014) of an AAV8-mediated self-complementary 
hFIX gene transfer trial for severe hemophilia B demonstrated long-term expression of FIX 
activity levels with mean levels (±SD) 5.1 ±1.7% of normal in 6 participants at the highest dose 
level of 2x1012 vg/kg, over a median period of 3.2 years after vector administration.  No vector- 

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and procedure-related safety concerns were observed in the initial study or the 3-year LTFU.  Four 
out of these 6 participants developed an asymptomatic rise in hepatic transaminases between 
Weeks 7 and 9 after vector administration, which required a short, approximately 8-week tapering 
course of prednisone therapy (Nathwani, 2014) to prevent loss of FIX transgene expression.  The 
recent results from an AAV5-mediated B-domain-deleted human factor VIII (AAV5-BDD-
hFVIII; BMN-270) gene transfer trial for severe hemophilia A resulted in sub-therapeutic levels 
(0.6% FVIII activity levels) over 34 weeks in 1 participant at 6x1012 vg/kg (low dose-level),  
transgene FVIII activity levels 2.3% of normal over 26 weeks in 1 participant at 2x1013 vg/kg 
(middle dose-level), and lastly, FVIII activity levels 5 - 271% of normal in 7 participants at  6x1013 
vg/kg (high dose-level)  in the first year after vector infusion (Rangarajan, 2017). However, longer-
term follow-up has shown a gradual decline in FVIII levels in the circulation. Thus, at year 1, 6 
out of 7 participants show FVIII within the normal range, and 1 out of 7 in the range of mild 
hemophilia. At year 3, 1 out of 7 remains in the normal range, 5 out of 7 are in the mild hemophilia 
range, and 1 out of 7 is in the moderately severe hemophilia range.  At the year 3 median of 19.9%, 
half of the participants are either at or approaching expression levels associated with bleeding 
events. In that trial, in order to avoid the asymptomatic rise in hepatic transaminases concomitant 
with the loss of transgene FVIII activity levels, all 7 participants receiving the highest dose of 
BMN-270 received a course of steroid therapy. Six participants received prophylactic 
corticosteroid regimens starting 3 weeks after the vector administration. These 6 participants given 
prophylactic corticosteroids had exposure from 15 weeks to at least 35 weeks in 1 participant (Pasi, 
2020).  
The Sponsor conducted a clinical study of a novel bio-engineered rAAV vector encoding the high-
specific activity FIX variant vector (AAV-Spark100-hFIX39-Padua or SPK-9001) for hemophilia 
B (IND 16437).  The first 10 participants who received the initial dose level of 5x1011 vg/kg, 
achieved endogenous FIX activity levels ranging from 14-81% (High, 2016; George, 2017).  
Steady-state FIX expression was reached by 12 weeks after the infusion of SPK-9001, resulting in 
a mean FIX activity level of 33% of normal.  Natural history data of patients with hemophilia 
suggests that circulating factor levels of approximately 12% of normal are required to protect 
against spontaneous joint bleeds (den Uijl, 2011).  All participants dosed with SPK-9001 have 
discontinued routine infusions of FIX concentrates.  One participant with severe joint disease self-
administered precautionary infusions for knee pain. In the study to date, no SAEs have been 
reported, including no factor IX inhibitors and no thrombotic events. Two of the 10 participants 
experienced an asymptomatic, transient elevation in liver enzymes, or decline in FIX activity, 
potentially indicative of an immune response to the vector capsid, that occurred several weeks post 
infusion. Both participants received a tapering dose of oral corticosteroids, after which their 
alanine aminotransferase (ALT) levels returned to baseline  
A vector that can safely and consistently achieve sustained high levels of FVIII activity and 
potentially eliminate spontaneous hemarthroses are the goals for the incorporation of gene transfer 
into hemophilia care. 
The objective of this study is to determine the safety, tolerability, and transgene-derived FVIII 
activity levels of a single IV infusion of SPK-8011 (AAV-Spark200-BDD-hFVIII) in individuals 
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2.5 
Rationale for Dose and Schedule Selection 
Planned dose levels include 5x1011, 1x1012, 2x1012, and 1.5x1012 vg/kg of SPK-8011. 
At the proposed starting clinical dose of 5x1011 vg/kg, FVIII activity levels around 3% of normal 
are hypothesized to be achieved, based on studies in cynomolgus macaques (see Section 2.2.2). 
While a universal preclinical model to determine AAV dosage in humans does not exist, Spark’s 
previous experience in NHPs using AAV2, AAV8 and AAV-Spark100 vectors to mediate liver-
derived expression of coagulation factor IX indicates that macaque models have been a good 
predictor of vector efficacy in humans. More recently, chimeric “humanized” mice with livers 
partially repopulated with human hepatocytes have become a valuable tool to determine hepatic 
transduction efficacy of different viral capsids. 
 
 
  
Therapeutic rAAV-based gene transfer is hampered in individuals who develop neutralizing 
antibodies against AAV capsids.  Even if switching to a different vector serotype, participants are 
unlikely to qualify for future gene transfer clinical studies.  For this reason, the Sponsor proposes 
the clinical starting dose level of 5x1011 vg/kg, which may result in a reasonable therapeutic level, 
but also provides an ample safety margin for the participants. 
Safety of these dose levels is supported by previous and ongoing human clinical trials of AAV2, 
AAV5, AAV8, AAVrh10 and AAV-Spark100 vectors encoding hFIX or hFVIII, as well as the 
NHP studies with SPK-8011, in which dose levels up to 2x1013 vg/kg were infused without 
evidence of adverse effects. This dose level is ~10-fold higher than the proposed starting clinical 
dose level of 5 x1011 vg/kg in this clinical study. 
The Sponsor has previously demonstrated that the presence of an excess of empty capsids may 
adsorb low-level and non-neutralizing antibodies, permitting liver transduction after peripheral 
vector infusion even in their presence (Mingozzi, 2013b). This hypothesis is consistent with the 
clinical data from previous AAV-mediated hemophilia B gene transfer trials, in which the presence 
of empty capsids in the formulation correlated well with higher expression levels at low vector 
doses (Monahan, 2015; Nathwani, 2014). For this reason, the final formulation of SPK-8011 may 
contain a mixture of empty and full capsid particles. 
 
 
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3 
OBJECTIVES AND ENDPOINTS  
Objectives 
Primary 
• To evaluate the safety and tolerability of SPK-8011. 
• To evaluate the efficacy of SPK-8011. 
Secondary 
• To determine the PK characteristics of SPK-8011. 
• To characterize the immune response to the vector and transgene product.  
Endpoints 
Primary 
• For safety and tolerability: 
o Clinically notable changes from baseline in physical examinations and vital signs. 
o Incidence of adverse events, including clinically significant abnormal laboratory 
values. 
o Hepatic transaminase elevation requiring immunosuppression. 
• For efficacy: 
o Primary kinetic parameters of peak and steady-state FVIII activity levels assessed 
by coagulation clotting assays. 
o Number of FVIII infusions after vector administration. 
o Number of bleeding events (spontaneous and traumatic) after vector 
administration. 
Secondary 
• Additional kinetic assessments will include, but not limited to:  
o Time to achieve steady-state FVIII activity level;  
o Vector-shedding of SPK-8011-101 in bodily fluids. 
• Incidence of immune responses to AAV capsid protein and BDD-hFVIII transgene. 
Exploratory 
• Joint assessments:  
o Number of target joints 
o Hemophilia Joint Health score 
• Activities assessments:  
o Hemophilia Activities List  
o Change in Level of Activity questionnaire 
• Quality-of-life assessments:  
o Haem-A-QoL questionnaire  
o Euro Quality of Life Five Dimensions Questionnaire (EQ-5D-5L) 
questionnaire 
• Health-economic parameters to include, but not limited to, collection of information 
on the following: 

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o Number of hospitalizations (excluding pre-planned hospitalizations 
documented at screening) 
o Number of hospitalization days 
o Number of emergency room visits 
o Number of physician visits, excluding study visits 
o Number of days off school or work 
• Exploratory inflammatory profiling of plasma and immune function gene expression 
of PBMC after vector administration (ELISpot, and other exploratory biomarkers) 

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4 
STUDY DESIGN 
4.1 
Overall Design 
This is a Phase 1/2a, open-label, non-randomized, dose escalation study to evaluate the safety, 
tolerability, and efficacy of a single IV infusion of SPK-8011 in men with severe hemophilia A.  
Up to 50 eligible participants will be dosed with a single IV infusion of SPK-8011.    
4.1.1 Sequence of Enrollment 
The following 2 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 Products ( U.S. Food and Drug Administration, 2015):   
• The first 2 participants in each dose-level (5x1011 vg/kg, 1x1012, 2x1012 vg/kg) will be 
infused with SPK-8011 at least 6 weeks apart to mitigate acute safety risk; and  
• An independent DMC will review at least 6 weeks of follow-up data from up to 4 
participants who have received SPK-8011 at a given dose level prior to dosing the first 
participant in the next dose level.  
The 1.5x1012 dose arm was initially evaluated in 3 participants using prophylactic corticosteroids 
(Amendment 4) and 1 participant using reactive corticosteroids (Amendment 5).  This dose will 
be further evaluated using 2 cohorts to explore immunomodulation. Cohort 1 will utilize 
 
. Reactive 
corticosteroids will be permitted in Cohorts 1 and 2, if indicated, in response to clinical 
observations consistent with an immune response that occurs despite TCZ or MMF. Use of 
azathioprine, MMF, and/or tacrolimus will be permitted in any participant should a steroid sparing 
regimen be indicated, based on the clinical judgement of the Investigator and in consultation with 
the Sponsor. The steroid sparing approach will include consideration of individual risk including 
potential toxicity that may result from interactions with concomitant medications.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Reactive corticosteroids will be permitted in Cohort 2, if indicated, in response to clinical 
observations consistent with an immune response that occurs despite TCZ. Use of azathioprine, 
MMF, and/or tacrolimus will be permitted in any participant should a steroid sparing regimen be 
indicated, based on the clinical judgement of the Investigator and in consultation with the Sponsor. 
The steroid sparing approach will include consideration of individual risk including potential 
toxicity that may result from interactions with concomitant medications.  
Cohort  
Number of 
Participants  
SPK-8011 Dose  
1  
3-5  
1.5x1012 vg/kg  
2  
3-5  
1.5x1012 vg/kg  
*
 
 
Continued enrollment will alternate between Cohorts 1 and 2 of 1.5x1012 vg/kg. A stagger of 6 
weeks will occur between the first and second participants in Cohort 2.  If in the opinion of the 
Investigator and Sponsor, there are individual or site-specific circumstances that might preclude 
enrollment in either cohort in an otherwise eligible participant, enrollment in the alternate Cohort 
may be considered (i.e., HIV status, timely access for IV steroid administration based on 
geographic location).  
Dose-Level and Cohort Expansion- 
Dose-cohort expansion may occur under the following scenarios: 
Dose Level Expansion - After 2 participants are dosed in a given dose level, it may be possible to 
expand a cohort to up to 10 participants if there is evidence of FVIII:C increases above 5% of 
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normal in either participant by Week 4 post vector-administration.  This initial expansion will 
provide additional information about variability of response within the same dose level. 
New Cohort Expansion - After 2 participants are dosed in a cohort, an initial expansion of up to 
3 participants may occur and, thereafter, an additional expansion for up to a total of 10 participants 
may occur. The additional expansion may occur in 1 or more cohorts. For Cohorts 1 and 2 of the 
1.5x1012 dose, the first 2 participants will be infused at least 6 weeks apart.  If either of the 
immunomodulatory regimens are successful and if agreed to by the DMC, a third Cohort will be 
introduced using that same 
 SPK-8011. 
Dose Escalation-  
The decision to dose escalate will be made by the Sponsor in consultation with the DMC to ensure 
safety. 
Dose escalation to the next dose level may occur under the following scenarios, provided there are 
no safety concerns after at least 6 weeks of follow-up data have been reviewed by the DMC. Dose 
escalation through the first 3 dose levels (5.0x1011 vg/kg, 1.0x1012, 2.0x1012 vg/kg) may occur in, 
but is not restricted to, the following scenarios. 
Dose escalation may be considered if: 
i. 
If neither of the first 2 participants achieve FVIII:C above 5% of normal by Week 6 
post vector-administration; or 
ii. 
If at least 2 participants in a given cohort achieve FVIII:C ≤ 40% of normal by Week 
6 post-vector-administration; or 
iii. 
If 3 participants in a given cohort achieve ‘steady-state’ FVIII:C ≤ 50% of normal. 
There will be no dose escalation if at least 3 participants in any dose level achieve steady-state 
FVIII:C > 80% of normal.  Steady-state levels are based on at least 2 separate FVIII:C 
measurements, at least 2 weeks apart, starting 8-12 weeks post-vector administration while not 
receiving daily corticosteroid therapy and without use of exogenous FVIII products since vector 
administration. 
It is expected that corticosteroid therapy may increase the transgene expression from the SPK-
8011 expression cassette, as observed in both animal models and in our clinical observations using 
both early prophylactic and the reactive application of corticosteroids. This effect appears to occur 
in a dose-dependent fashion; in clinical observation the effect has appeared somewhat greater with 
initiation of daily oral corticosteroids in a prophylactic fashion in the early weeks after vector 
delivery when compared to reactive corticosteroids given at later time points. The Primary 
Endpoint for efficacy for this study is the FVIII activity at steady state, which Spark does not 
interpret while any participant remains on corticosteroid treatment. Instead, expression level of 
steady-state FVIII:C as an efficacy endpoint is evaluated after daily oral corticosteroids or 
 
steroids have been discontinued for at least 2 weeks. Note that were the concomitant use of steroids 
to have an effect to artifactually increase FVIII expression to a level greater than the eventual 
steady state expression (after discontinuation of steroids), this would not trigger an inappropriate 
escalation of the SPK-8011 dose (which would be a safety concern) but instead might result in an 
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expansion of the present dose cohort or a delay in the decision to dose escalate until after the 
observation of steady state while off steroid therapy. Nevertheless, at the time of the current 
protocol version, the SPK-8011 vector has already been observed in this clinical trial following 
escalation across the entire range from 5x1011 vg/kg through 2x1012 vg/kg of SPK-8011. No 
participant has achieved the ceiling expression level of steady-state FVIII:C > 80% of normal that 
is detailed above.  
Tocilizumab is expected not to influence levels of the expression of the transgene product, as 
evaluated in pre-clinical animal studies (summarized in Section 2.2.4). Tocilizumab is also not 
expected to influence or confound the estimation of the treatment effect of the vector to correct 
deficient levels of FVIII. 
MMF is expected not to influence or confound the estimation of the treatment effect of the vector 
to correct deficient levels of FVIII. MMF was administered in 2 participants in this study, SPK-
8011-101, as of 24 November 2020, and did not appear to have an influence on the transgene 
expression of FVIII.   
After escalation through the first 3 planned dose levels, an intermediate dose level (e.g., 
1.5x1012 vg/kg of SPK-8011), was agreed upon with the DMC. Additionally, the Sponsor may 
decide to further expand the starting dose cohort (5x1011 vg/kg), the middle dose cohort (1x1012 
vg/kg), or the high dose cohort (2x1012 vg/kg) to better evaluate the safety, efficacy, and variability 
of response within a given cohort. Any decision to add an intermediate dose level or further expand 
one of the existing protocol-defined dose levels will be made in consultation with the DMC.  
In consultation with the DMC, further dose exploration may be considered if effective 
immunomodulation has been demonstrated in any cohort and/or FVIII expression is less than 80% 
of normal 12 weeks following gene transfer in at least 2 participants. 
4.1.2 FVIII Incremental Recovery 
If FVIII levels resulting from endogenous FVIII production from transduced hepatocytes begin to 
decline without evidence of elevation of transaminases, the participant will be evaluated for 
evidence of anti-FVIII antibody formation. This evaluation will include FVIII inhibitor assays and 
FVIII incremental recovery with blood sample collection consistent with the investigator’s clinical 
practice after receiving 50 IU/KG of FVIII product. Blood sampling will be done at appropriate 
time-points to enable acceptable determination of PK parameters (Iorio, 2016). 
4.1.3 Corticosteroids  
Based on observation and experience from earlier clinical studies of liver-directed AAV gene 
transfer, including the SJ-UCL trial (Nathwani, 2011b; Nathwani, 2014), the Sponsor’s earlier 
clinical studies (IND 9398, IND 15149, and IND 16437), and the Baxalta BAX 335 trial 
(NCT#01687608), participants may develop an immune response to the vector capsid, as 
evidenced by a transient rise in transaminases (AST and/or ALT) and/or a loss in FVIII activity in 
the peripheral blood, as measured by IFN-ɣ ELISpot (Manno, 2006; Mingozzi, 2007; Nathwani, 
2011b).  Of the 7 initial participants treated in the third dose cohort with 2x1012 vg/kg SPK-8011, 

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5 required corticosteroids, starting at 6 to 11 weeks post vector infusion for one or more of the 
following triggers: declining FVIII levels, rise in ALT above participant baseline or elevated IFN-
ɣ ELISpots to AAV capsid. Steroid initiation normalized ALT levels and extinguished the ELISpot 
signal in all cases. Two of the 5 participants who received corticosteroids in the 2x1012 vg/kg dose 
group, however, showed loss of transgene expression likely due to the immune response. Both 
these individuals eventually returned to hemophilia prophylaxis regimens, one with recombinant 
FVIII, the other with emicizumab. Based on clinical experience with FIX, there is no evidence that 
there is significant hepatic toxicity related to these transient elevations, and most appear to resolve 
spontaneously without symptoms. In the FIX Phase 1/2 study, 3 of 15 participants receiving a dose 
of 5x1011 required a short course of oral corticosteroids (George, 2017; George, 2019) due to 
elevation of the ALT above the patient’s baseline. These transient elevations may be accompanied 
by a decrease in factor activity (Manno, 2006; Nathwani, 2011b).  Given that 5 of 7 participants 
in the 2x1012 vg/kg group required corticosteroids, including 2 participants who lost FVIII 
expression, the institution of a consistent, standardized short course of prophylactic corticosteroids 
appeared warranted in an attempt to pre-emptively manage potential immune responses. This 
approach has been used in other trials where AAV has been administered systemically (including 
hemophilia NCT#02576795; Rangarajan, 2017, and spinal muscular atrophy NCT#02122952; 
Mendell, 2017). This protocol was amended to incorporate prophylactic steroids, beginning 4 
weeks after vector infusion and continuing in a tapering regimen until at least 12 weeks post vector 
infusion (Protocol Version 4).  In the first 2 participants administered SPK-8011 at 2x1012 vg/kg 
using prophylactic oral corticosteroids (
), the first was started on 
corticosteroids on Day 27 due to falling FVIII and the second was started on Day 26 due to rising 
ALT and decreasing FVIII expression. In both these participants, early initiation of corticosteroids 
resulted in a transient supraphysiologic increase in FVIII levels to greater than 200%.   
Based on discussions with the study’s independent Data Monitoring Committee, an intermediate 
dose cohort (1.5x1012 vg/kg) was initiated.  Reduction of the vector genome dose was successful 
in terms of avoiding supraphysiologic levels of FVIII upon initiation of corticosteroids, but in all 
participants where corticosteroids have been started prior to 6 weeks post vector infusion, tapering 
off has been challenging, and consequently, prolonged courses have been required, with associated 
steroid related side effects. In 2 individuals, cessation of corticosteroids (initiated early, at 
approximately 4 weeks) was followed by a return of positive IFN-γ ELISpots against capsid, 
decline in FVIII levels, and increases in ALT/AST. Restarting corticosteroids returned 
transaminases to baseline levels and stabilized FVIII levels. In some cases, it has been clinically 
necessary to initiate a steroid sparing regimen(s) (e.g., azathioprine, tacrolimus) to aid in the 
prednisone taper. In these participants, a steroid sparing agent has allowed a taper of the prednisone 
dose to 
. Because of the need for prolonged steroid taper when 
steroids were administered beginning at 4 weeks, which was not observed with later initiation of 
steroids, prophylactic steroids will be avoided going forward.  
At the lower doses of SPK-8011 which demonstrated durable FVIII expression associated with 
hemostatic protection, transient elevations of hepatic transaminases have been adequately 
attenuated using a tapering course of oral corticosteroids, consistent with the experience in liver-
directed AAV gene therapy trials for hemophilia B.  At the highest dose of SPK-8011 tested 
(2x1012 vg/kg) reliance upon reactive or early prophylactic tapering courses of daily oral 
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corticosteroids have not yielded satisfactory outcomes.  Although the FVIII activity levels returned 
to the normal range in both participants administered 2x1012 vg/kg as the prophylactic oral 
corticosteroid dose was tapered, the transient supraphysiologic levels represented a potential safety 
concern.  Reactive oral corticosteroids, initiated promptly, did not prevent complete loss of 
transgenic FVIII expression in 2 participants.  
 
, given in an attempt to prevent 
, was associated with the observation of delayed and prolonged signals of 
hepatic inflammation, greatly extended prednisone exposure, and corticosteroid-associated side 
effects.  Specifically, for the purpose of maintaining immune quiescence while completing 
corticosteroid taper, three additional immune modulating agents (tacrolimus, MMF, and 
azathioprine) have been used.  
Based on discussions with expert immunology consultants, the Sponsor proposes to again 
investigate administration of steroids only in response to one of the previously described triggers, 
i.e., declining FVIII levels or rising transaminases, using IV 
 steroids as the preferred method. 
Oral corticosteroids may be utilized, if clinically indicated.  ELISpot is an exploratory assay and 
not used as a clinical predictor for immunomodulation. 
The reactive approach using IV corticosteroids seeks to potentially optimize the reactive use of 
corticosteroids when initiated in response to clinical signals of transduced hepatocyte loss. This 
approach explores IV 
 methylprednisolone as an alternative to daily tapering oral prednisone.  
Experience with the use of IV 
corticosteroids in a variety of autoimmune disorders, including 
during organ-threatening disease flares, suggests efficacy with potentially limited exposure (when 
compared to tapering daily oral regimens). Supportive care with the additional immunomodulators 
tacrolimus, MMF, or azathioprine may be employed to spare cumulative steroid exposure, and the 
possible side effects of these potential supportive adjuncts are reviewed.  
In light of the complications observed with prolonged exposure to corticosteroids observed in 4 
participants in Study SPK-8011-101, Cohorts 1 and 2 will be investigated to prevent the initiation 
of the 
, evaluated in a separate study group. Cohorts 1 and 
2 will receive MMF and TCZ, respectively, 
. Prophylactic 
corticosteroids will not be explored; should apparent immune mediated hepatocyte loss be 
observed, support with reactive corticosteroids may be initiated. 
Significant elevations of transaminases (≥ 5-10 x ULN) will be treated as a safety issue and 
appropriate medical care will be instituted according to the standard of care of the medical facility 
involved.  
Based on the data observed to date in this trial as well as in Hemophilia B trials (Manno, 2006; 
Nathwani, 2014), a course of corticosteroids may be initiated in participants, depending on the 
clinical judgement of the investigator and in  consultation with the Sponsor, after a trigger is 
identified in the transaminases or FVIII post vector transfusion and may be continued in a 
 
or tapering regimen, IV and/or oral, until clinical concern of hepatic inflammation is resolved and 
per investigator/Sponsor discretion. 
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4.1.3.1  Corticosteroid Regimen   
If transaminases become elevated or the FVIII declines, IV corticosteroids (methylprednisolone at 
 for 3 consecutive days and repeated 1 week following the 
 is recommended in 
consultation with the Sponsor. 
 IV corticosteroids may be followed by a maintenance daily 
dose of approximately 
 or until the next course of 
 
corticosteroids. The 
 steroid interval should taper when the transaminases and FVIII have 
stabilized.  
IV 
 corticosteroids are the preferred approach. The suggested regimen is IV 
methylprednisolone 
 and repeated 1 week following the 
 if immune triggers 
are not resolved.  A remote provider or home nursing service may be utilized for the administration 
of IV corticosteroids. In these instances, storage of IV medication and supplies may be required in 
the home. Local policies and procedures for home storage and nursing care should be followed.  
Additional weekly 
 steroid courses may be repeated in response to a trigger from the 
transaminases or FVIII level. The 
 course should reduce in frequency to 
 
 Treatment will continue until resolution of the immune 
response occurs and may require the use of additional immunomodulatory agents. Daily oral 
corticosteroids given in a tapering dose regimen may be utilized instead of IV 
 corticosteroids, 
if in the estimation of the Investigator an oral dosing regimen is clinically indicated. The 
Investigator in collaboration with the Sponsor will have flexibility in implementing the 
corticosteroid regimen, since the exact regimen and course will depend on clinical circumstances. 
If reactive corticosteroids (IV 
 or oral dosing) are triggered by an apparent immune response, 
additional blood samples for immune profiling (cytokines) and PAX gene should be collected 1) 
prior to the initiation of corticosteroids (if this is possible without delaying the initiation of 
corticosteroid therapy), and 2) at 1 week (±2 days) and at 2 weeks (±2 days) following the first 
dose of corticosteroids. At the discretion of the investigator, nucleic acid amplification testing 
(NAAT) for infection with SARS-CoV2 (the infectious agent in COVID-19) may be performed at 
this time for individuals who do not have symptoms consistent with upper or lower respiratory 
tract infection or COVID-19. NAAT testing should be performed at this time for individuals with 
any of the following symptoms: cough, shortness of breath or difficulty breathing, fever, chills, 
sore throat, new loss of taste or smell; new persistent/recurrent muscle pain or headache. For 
individuals who do not have any of these symptoms, the initiation of reactive corticosteroids 
should not be delayed pending results of NAAT testing. For individuals who do display any of 
these symptoms, initiation or corticosteroids may at the discretion of the investigator be delayed 
until after results of NAAT testing are known. Note: The Infectious Disease Society of America 
panel suggests collecting nasopharyngeal, or mid-turbinate or nasal swabs rather than 
oropharyngeal swabs or saliva alone for SARS-CoV2 RNA testing in symptomatic individuals 
with upper respiratory tract infection (URTI) or influenza like illness (ILI) suspected of having 
COVID-19. 
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4.1.3.2 Other Immunomodulatory Considerations 
Prolonged courses of high dose oral corticosteroids are undesirable and associated with AEs. In 
the AASLD and the EASL guidelines for the treatment of autoimmune hepatitis, an alternative 
regimen of corticosteroids and steroid sparing agents, azathioprine, MMF, or tacrolimus, is 
outlined for use in individuals who cannot tolerate high doses of prednisone or are experiencing 
difficulty tapering. A steroid-sparing agent administered concurrently with lower (compared to 
prednisone monotherapy) and tapering doses of prednisone may be utilized based on individual 
clinical circumstances. Azathioprine, MMF, and tacrolimus have been utilized as steroid-sparing 
agents in the most recent iteration of this study, to good effect in each case, and are described 
below. 
 mg may be considered in participants who are having difficulty tapering off 
prednisone, however 
 
may be necessary to prevent hepatotoxicity. The
 
in consultation with the sponsor. 
 
ay also be considered as a primary or second line 
agent in a steroid sparing regimen. 
An alternative option may be considered of using tacrolimus (another immunomodulatory agent 
that antagonizes activation and proliferation of T cells) 
 
 to the participants who are not responding to corticosteroids or currently failing the steroid 
taper, in an effort to reduce or stop the prednisone. Therapeutic drug monitoring will be done twice 
per week with the aim of 
. Timing of trough 
levels may be altered by the Investigator based on clinical response. The tacrolimus dose 
 
 and the prednisone will be tapered subsequently.
 
 
 
  
The ultimate determination of steady state FVIII expression and determination of expression above 
a threshold FVIII:C activity value are interpreted by evaluating serial FVIII:C activity over 
multiple timepoints examined after discontinuation of corticosteroids and steroid-sparing immune 
suppressive agents.  
4.1.3.3 Prophylactic Use of TCZ and MMF 
The data from the non-GLP study in NHPs described in Section 2.2.4 provides proof-of-concept 
that blockade of IL-6 signaling by administration of the humanized monoclonal antibody prior to 
AAV infusion can reduce both the innate and adaptive immune responses to AAV. In Cohort 2, 
 
 
 
 followed by 
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evaluation of the data by the Sponsor in consultation with the Data Monitoring Committee as 
detailed in Section 4.1.1.  
The data using MMF with AAV8-hAAT-hFIX16 is described in Section 2.2.5. It may be 
appropriate to utilize immunosuppressive regimens that may prevent vector-induced hepatitis with 
MMF at 
 MMF 
 
 There is extensive experience with the proposed 
immunomodulatory regimens, for example in people with asthma, idiopathic thrombocytopenic 
purpura, and other medical conditions. For participants with severe hemophilia A, the benefit of 
long-term expression of a modest level of clotting factor outweighs the risk of a several-week 
course of immunosuppression. In Cohort 1, 
 
 
 
4.1.3.4 Experience with Long Term Immunomodulation 
There is extensive experience with corticosteroids and immunosuppressive regimens in 
hemophilia: first, as a manoeuvre to eradicate antibodies to factor VIII or IX, clinically termed 
inhibitors (Nilsson, 1976; Hultin, 1976; Hay, 2006) and second, in the setting of liver 
transplantation due to the high prevalence of hepatitis C among adults with hemophilia (Gordon, 
1998; Wilde, 2002).  Many individuals with hemophilia have been maintained on standard liver 
transplant immunosuppression regimens for years. Corticosteroids have been used to treat people 
with asthma, idiopathic thrombocytopenic purpura, organ injury from autoimmune diseases 
including autoimmune hepatitis and systemic lupus erythematosus nephritis and lupus CNS 
manifestations, and other medical conditions. For participants with severe hemophilia A, the 
benefit of long-term expression of a modest level of clotting factor far outweighs the risk of 
receiving a course of corticosteroids or other immunomodulatory agents. 
The long-term side effects of the immunomodulatory drugs expected to be used in this study are 
well-characterized.  Participants who develop immune hepatitis will be monitored closely to 
minimize the risk of the side effects. 
 of steroids has been shown to be efficacious in 
reducing an immediate immune response with a reduction in corticosteroid related AEs (when 
compared to daily high dose oral corticosteroids) in several autoimmune diseases (Fanouriakis, 
2019; Gordon, 2018; Wei, 2016). The use of 
 
 may reduce the reactivation of the inflammatory process or rebound of the immune 
response; however, a standard regimen has not been determined (Gordon, 2018; Torres, 2018).  To 
utilize the lowest effective dose and shorten the duration of the immunosuppressive therapies, 
tapering of the regimen will start as soon as there is evidence of resolution of hepatic transaminase 
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. Participants should receive Pneumocystis jiroveci pneumonia prophylaxis 
while on immunosuppression. 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 (e.g., hyperglycemia, weight gain, infections, acute 
exacerbation of hypertension or mood disorder, insomnia) will be recorded as AEs and attributed 
to immunomodulation, and medications may be prescribed at the discretion of the Investigator.   
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Individual participant recommendations regarding the use of alternative and/or additional 
immunomodulatory regimens or therapies (other than corticosteroids); e.g., azathioprine, MMF, 
and/or tacrolimus will be discussed with the Investigator(s) and the Sponsor and will involve a 
thorough review of the participants medical history, labs, concomitant medications, and clinical 
presentation. Depending on the agent selected, additional blood draws for therapeutic or laboratory 
monitoring and subsequent dosage adjustment may be required. The Investigator will discuss the 
risks and benefits of any immunomodulatory therapy with the participant and will consult with 
additional experts as needed (i.e., transplant surgeon, hospital pharmacist, infectious disease 
specialist, endocrinologist etc.). Even though there is clinical experience with the use of these 
drugs in HIV positive patients, immunomodulatory potential of TCZ in cohort 2 will first be 
evaluated in 2 participants who are HIV negative. 
4.1.4 Screening 
Participants who have provided consent will undergo the screening assessments described in the 
Schedule of Events, up to 16 weeks prior to the infusion of SPK-8011. If there is no historical ≤1% 
FVIII activity levels documented by the certified laboratory, then the screening data must be 
generated documenting ≤2% FVIII activity at baseline.     
Re-screening: Re-screening is permitted once, if the participant is found to be eligible for the 
study but the screening period is prolonged greater than 16 weeks. A participant may be re-
screened into the study using the same participant ID; however, all screening assessments must be 
repeated. 
4.1.5  Three to Seven Days Prior to Day 0  
Participants in Cohorts 1 and 2 will require a laboratory assessment 3 to 7 days prior to Day 0 to 
verify continued eligibility 
 
 (see Schedule of Events)).  This visit may be conducted by a remote provider. The 
study staff must contact the participant to verify and document no changes in the general 
health status 
. 
4.1.6 Day -2 
Participants in Cohort 1 will start
 
 
4.1.7 Dosing Day (Days 0, 1) 
Assessments and procedures to be performed on Dosing Day (Day 0) are described in the Schedule 
of Events. All participants will administer a prophylactic infusion of 50 IU/kg of their current 
FVIII concentrate the morning of Day 0.  This may be self-administered and recorded in the 
participant’s Infusion Log.  Site assistance is permitted for the FVIII infusion. On Day 0, 
participants in Cohort 2 will then receive a dose of
 
 
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. The TCZ dose will not exceed 
. (Please see Actemra® Prescribing 
Information [Genentech, 2019]). Participants will receive a single IV infusion of SPK-8011 at the 
vector-administration center.  The complete dose of SPK-8011 will be infused via infusion pump 
over approximately 60 (±2) min.  Vital signs will be taken at various time-points from the start of 
infusion (see Schedule of Events). 
Blood samples for immune profiling will be collected pre-administration of TCZ or MMF (
 
), and pre-administration of SPK-8011, and 30 (±2) min,  2 hours (±10 min), 5 
hours (±10 min), and 24 (±1) hours after the completion of the SPK-8011 infusion. PAX Gene will 
be collected pre-administration of TCZ or MMF (3-7 days prior to Day 0), pre-administration of 
SPK-8011, 5 hours (±10 min) and 24 (±1) hours after the completion of the SPK-8011 infusion. 
Additional blood samples, including for FVIII activity levels, will also be collected pre- and post-
infusion of SPK-8011. 
4.1.8 Follow-up Observation Period 
Participants who have received a dose of SPK-8011 will report to either the vector-administration 
center or follow-up center for follow-up evaluations, according to the protocol assessments for 52 
(±2) weeks after the infusion of SPK-8011.  During the follow-up observation period, a 
qualified/trained in-home service provider may be utilized, if needed, for remote-phlebotomy and 
sample-collection services during the visits which do not require physical examination. For 
participants in Cohorts 1 and 2, MMF and TCZ, respectively, may be continued as described in 
Section 4.1.3.3. In the event that serious infections or malignancies such as lymphoma occur and 
are assessed as possibly related to either MMF or TCZ, no re-administration of MMF or TCZ shall 
be allowed to the participant. 
4.2 
Study Duration, Enrollment and Number of Sites 
4.2.1 Duration of Study Participation 
The study will consist of the following phases: 
• Screening period (up to 16 weeks)  
• Study 
Intervention: 
Assignment 
into 
cohort 
with 
possible 
pre-infusion 
immunosuppressive medication or administration of oral immunosuppressive 
medication, and then study product infusion 
• Follow-up observation period (52 [±2] weeks post-infusion of SPK-8011)   
The total duration of the study for an individual participant is up to 68 weeks (including up to 16 
weeks of screening).   
4.2.2 Total Number of Participants; Sites Projected and Geographic Regions 
It is estimated that approximately up to 100 potential participants may be enrolled for a maximum 
of 50 evaluable (i.e., dosed) participants.  
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The study is planned to be conducted at approximately 20 study centers (vector-administration 
centers and/or follow-up centers) located worldwide.  
4.3 
End of Study Definition 
A participant is considered to have completed the study if he has completed all phases of the study 
including the End of Study (EOS) visit in the Schedule of Events. 
The EOS is defined as the date of the last participant’s last visit (LPLV). 
4.4 
Study Stopping Rules  
The Sponsor may terminate this study at any time.  The Sponsor, or designee, will notify the 
Investigator(s) and appropriate regulatory authorities if the study or any given study cohort is 
suspended, terminated or completed.  If the study or any given study cohort is suspended or 
terminated, the following instructions should be followed, unless the DMC and/or the Sponsor 
advise otherwise: 
• Participants who have already received SPK-8011 will continue to maintain the 
protocol schedule;  
• Participants who are in the screening phase of the study or study cohort but have not 
received SPK-8011 will wait for DMC recommendation.  The scheduled date for SPK-
8011 infusion may be postponed or cancelled. 
Any of the following occurrences may result in suspension of further enrollment in the study or 
any given study cohort while the events are under investigation: 
• Any SPK-8011 related death during the study; 
• The development, in any participant, of SPK-8011 related Grade III-IV toxicity, 
including, but not limited to confirmed persistent FVIII inhibitor, allergic reaction 
(bronchospasm and anaphylaxis), excluding elevated transaminases;   
• The development, in any participant, of SPK-8011 related Grade IV (> 10 x ULN) 
elevated transaminases; 
• The development, in any participant, of SPK-8011 related Grade I or higher (> 2.5x 
ULN) elevated transaminases that fail to resolve to less than 2.5x ULN within 4 weeks 
on an immunomodulatory regimen;   
• The occurrence, in any participant, of a medically important event that warrants further 
evaluation; 
• Any occurrence of a malignancy at any point after vector infusion that is related to 
SPK-8011-101 or one of the immune modulating agents.   
* It is important to note that AAV vector-mediated insertional mutagenesis, if it should 
occur, is not likely to be observed in the initial year following gene transfer; therefore, 
the Sponsor intends to provide long-term safety monitoring of participants in a LTFU 
study. 

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In addition to halting enrollment, such an event will be handled as a SAE and reported in the time 
frame according to Section 9.4.2 of the protocol.  The DMC will review data relevant to the event 
and will receive information from the Sponsor and/or Investigator before providing appropriate 
recommendations.  The event and the DMC’s recommendation will be discussed with the U. S. 
Food & Drug Administration (FDA) and other regulatory authorities prior to re-initiation of 
enrollment.  All participants who were infused with the study drug will continue to comply with 
the follow-up schedule according to the protocol. 

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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 must meet the following criteria at screening and prior to dosing of SPK-8011 (Day 
0) to be eligible for the study: 
1. Be able to understand the purpose and risks of the study and provide signed and dated 
informed consent and authorization to use protected health information (PHI) in 
accordance with national and local privacy regulations;  
2. Be male and ≥ 18 years of age;  
3. Have hemophilia A with: 
a. < 1% (< 1 IU/dL) endogenous FVIII activity levels as historically documented 
by a certified laboratory or screening data results; OR  
b. 1-2% (1-2 IU/dL) endogenous FVIII activity levels and > 10 bleeding events 
per year (in the last 52 weeks prior to screening); OR 
c. 1-2% (1-2 IU/dL) endogenous FVIII activity levels and on prophylaxis;  
4. Have had > 150 prior EDs to any recombinant and/or pd FVIII protein products or 
cryoprecipitates based on historical data from medical records/history; 
5. Have no prior history of hypersensitivity or anaphylaxis associated with any FVIII or 
IV immunoglobulin administration; 
6. No measurable inhibitor against FVIII at screening (i.e., < 0.6 Bethesda Units); no 
confirmed history of clinically significant FVIII inhibitor and no clinical signs or 
symptoms of decreased response to FVIII administration (Note: Family history of 
inhibitors is not exclusionary, nor remote (greater than 5 years) documentation of a 
single measurement of Bethesda titer of > 0.6 BU that is not accompanied by clinical 
evidence of failure to respond to infused FVIII concentrate) 
7. Have acceptable laboratory values sampled at screening and reviewed prior to Day 0: 
a. Hemoglobin ≥ 11 g/dL; 
b. Platelets ≥ 100,000 cells/μL; 
c. AST, ALT, alkaline phosphatase < ULN; 
d. Bilirubin ≤1.5x ULN (Bilirubin levels above the laboratory’s normal range are 
acceptable in individuals with a documented history or laboratory evidence of 
Gilbert’s Disease); 
e. Creatinine ≤2.0 mg/dL;  

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f. Absolute neutrophil count (ANC) ≥ 2000 per mm3; 
g. Fibrinogen antigen ≥ 180 mg/dL for TCZ in Cohort 2 
8. Agree to use reliable barrier contraception after the administration of SPK-8011 until 
notified by the Investigator or designee.  
5.2 
Exclusion Criteria 
If any of the following criteria exist at screening or prior to dosing of SPK-8011 (Day 0) 
participants are not eligible for the study:  
1. Have active hepatitis B or C. All participants must be screened for both active hepatitis 
B and C regardless of prior known history.   
a. Screening for hepatitis B: All participants must have a single sample at 
screening for each of the following tests: HBsAg (hepatitis B surface antigen), 
anti-HBc (total hepatitis B core antibody), and a HBV-DNA viral assay (nucleic 
acid test for hepatitis B virus DNA). 
i. A participant is not eligible if either HbsAg is positive or HBV-DNA is 
positive/detectable. 
ii. A participant is eligible if the anti-HBc is positive and both HBsAg and 
HBV DNA are negative, as this would be consistent with a prior 
infection of hepatitis B. Anti-HBc must be obtained in all participants 
to discriminate between acute infection and possible reactivation of 
hepatitis B during the trial (e.g., in participants with no prior history of 
hepatitis B). 
b. Screening for hepatitis C: All participants, including those who have never 
been treated or who have completed anti-viral therapy for chronic hepatitis C 
must have a single HCV-RNA load assay (also referred to as a nucleic acid test 
[NAT] for HCV RNA) at screening.  
i. A participant is not eligible if his HCV-RNA load assay is 
positive/detectable.  
ii. Participants treated with anti-viral therapy for chronic hepatitis C must 
have completed anti-viral therapy at least 6 months prior to screening 
and have a negative HCV-RNA at the time of screening. 
iii. Participants with a documented or self-reported history of HCV must 
have a single negative HCV-RNA at time of screening; 
2. Currently on antiviral therapy to treat their hepatitis B or C; 
3. Have significant underlying liver disease. A participant is not eligible with any of the 
following documented diagnoses, indicative of significant underlying liver disease: 
• Portal hypertension; or 
• Splenomegaly; or  

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• Hepatic encephalopathy. 
Any participant without any of these pre-existing diagnoses must have the following 
performed at screening: 
3a. 
Serum albumin measurement.  A participant is not eligible if the serum 
albumin level is below the lower limit of normal of the laboratory; and  
3b. A diagnostic test for liver fibrosis (e.g., FibroScan, FibroTest/FibroSURE, or 
AST-to-Platelet Ratio Index (APRI)).  A participant is not eligible if any of 
the following findings, which are indicative of fibrosis ≥ stage 3, are present: 
i. FibroScan score > 8.3 kPa units; or  
ii. FibroTest/FibroSURE > 0.48; or 
iii. AST-Platelet Ratio Index (APRI) > 1; 
If more than 1 diagnostic test result is available, then the FibroScan will be used as the 
primary consideration for eligibility. 
4. Have serological evidence of HIV-1 or HIV-2 with CD4+ counts ≤ 200/mm3. 
Participants who are HIV-positive and stable, with an adequate CD4+ count (> 
200/mm3) and undetectable viral load (< 50 gc/mL) measured twice in the 6 months 
prior to enrollment, and who are on an antiretroviral drug regimen, are eligible to enroll;    
5. Have anti-AAV-Spark200 neutralizing antibody titers ≥ 1:1; 
6. Have history of active cancer in the past 6 months, chronic infection, latent or active 
tuberculosis, uncontrolled immune disorder or other chronic disease, that the 
Investigator and/or Sponsor consider to constitute an unacceptable risk; 
7. Have been dosed in a previous gene therapy research trial within the last 52 weeks or 
participated in a clinical study with an investigational drug within the last 12 weeks 
prior to signing the informed consent;          
8. History of diverticulitis, diverticulosis requiring antibiotic treatment, or chronic 
ulcerative lower gastrointestinal disease that might predispose a patient to perforations;              
9. Any concurrent clinically significant major disease (such as liver abnormalities or type 
I diabetes, uncontrolled hypertension, vertebral compression) or any other condition 
such as active infections or COVID-19 or any other unspecified reasons that, in the 
opinion of the Investigator, and/or Sponsor, makes the participant unsuitable for 
participation in the study. At the time of screening, the investigator will consider the 
local geographic and institutional epidemiology of COVID-19 and other infectious 
pathogens when determining suitability of the participant for participation in the study, 
including consideration of the potential clinical relevance of additional screening; 
10. Planned surgical procedure in the next 12 months requiring FVIII prophylactic 
treatment; and 
11. Unable or unwilling to comply with the schedule of visits and study assessments 
described in the clinical protocol. 

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Participants who do not meet all the enrollment criteria may not be enrolled.  Any violations of 
these criteria must be reported in accordance with Sponsor and Internal Review Board (IRB) 
Policies and Procedures. 
5.3 
Screen Failures 
Screen failures are defined as participants who consent to participate in the clinical study but are 
not subsequently administered study drug. A minimal set of screen failure information will be 
collected for screen failures: demography, screen failure details, eligibility criteria, and, if 
applicable, any SAE. 
Individuals who do not meet the criteria for participation in this study (screen failure) may not be 
rescreened unless previous approval received from the Sponsor. 
5.4 
Enrollment of Participants 
Each participant will be assigned a unique participant identification (ID) number after the 
providing written informed consent.  The participant ID number will be used to identify the 
participant for the duration of the study.  Participant ID numbers will not be reassigned or reused. 
No participant may be dosed prior to obtaining the unique ID number.  The Investigator must 
confirm and verify the inclusion/exclusion criteria, following the review of screening results from 
the laboratory and other documents.  Participant ID numbers will be used to identify the participant 
for the duration of the study and may not be reassigned to another participant. 
5.5 
Randomization 
Not applicable.  This is a non-randomized study. 
5.6 
Blinding Procedures 
Not applicable.  This is an open-label study.   
 
 
 
 

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6 
STUDY PROCEDURES/ASSESSMENTS AND SCHEDULE 
6.1 
Safety Assessments 
6.1.1 Clinical Safety Assessments 
The following clinical assessments will be performed to assess the safety profile of SPK-8011: 
• 
Physical examination  
• 
Hemophilia medical history for the 52 weeks preceding screening (including number 
of FVIII infusions and number of spontaneous and traumatic bleeding episodes). 
• 
Target joint history for the 52 weeks preceding screening.  Joint status will be 
evaluated and assessed during this study using hemophilia joint health score.   
• 
Vital signs  
• 
AEs 
• 
Concomitant therapies and procedures. 
6.1.2 Laboratory Safety Assessments 
The following laboratory tests will be performed to assess the safety profile of SPK-8011: 
• Hematology 
• Clinical chemistry 
• Liver function tests   
• Coagulation  
• Neutralizing antibody development against FVIII by Bethesda assay (FVIII inhibitor)  
• Neutralizing antibody to AAV-Spark200 
• PBMCs to assess cellular immune responses 
• Inflammatory profiling of plasma after vector administration 
• Vector shedding (PBMC, serum, saliva, urine, semen) 
6.2 
Additional Assessments 
6.2.1 Joint Assessments 
Baseline clinical status of joints and identification of target joint(s) will be conducted during the 
screening or pre-vector infusion.  The Hemophilia Joint Health Score (HJHS) 2.1 will be 
performed to evaluate the clinical status of the joints at screening or prior to Day 0, Week 26 and 
Week 52. 
Joint health and identification of target joint(s) will be assessed during this study. A target joint is 
defined as a major joint (e.g., hip, elbow, wrist, shoulder, knee, and ankle) into which 3 or more 
spontaneous bleeds occurs in a single joint within a consecutive 6-month period as documented in 
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hemophilic arthropathy (e.g., synovitis, persistent swelling, effusion, limitation of range of motion) 
should be documented as part of the Joint assessment.    
The investigator will assess the participant’s target joint(s) identified at baseline by location of 
target joint(s), location of joint bleeding, and frequency of bleeding from each joint. 
6.2.2 Hemophilia Joint Health Score 
Joint assessment will be conducted using a HJHS (see Appendix 13.5).  This assessment is based 
on the scoring system used in a joint scoring reliability study in boys with hemophilia (Hilliard, 
2006).  It has been used as a tool to evaluate musculoskeletal outcomes in a cohort of 20 boys, 
aged 4 to 17 years (Trakymiene, 2010).   
Six joints (left ankle-LA, right ankle-RA, left elbow-LE, right elbow-RE, left knee-LK, right knee) 
will be scored according to the following criteria:  swelling, muscle atrophy, crepitus, flexion loss, 
extension loss, instability, joint pain, and strength.  Gait will be scored based on walking and 
climbing stairs.   
6.2.3 Activity Assessments (Changes in Level of Activity and Hemophilia Activities List) 
Changes in Level of Activity will be assessed at selected visits.  The participant will review the 
following 3 statements to confirm which more accurately describes any changes in his amount and 
intensity of physical activities in the past month.  
a) I have been doing more amount and more intensive physical activities. 
b) I have been doing fewer amount and less intensive physical activities. 
c) I have been doing about the same amount and intensity of physical activities. 
In addition to the Changes in Level of Activity, participants will complete the Hemophilia 
Activities List questionnaire (see Appendix 13.2) (van Genderen, 2004; van Genderen, 2006).  In 
the questionnaire, several activities are listed that could be difficult for patients with hemophilia. 
6.2.4 Participant Questionnaires 
The following questionnaires will be administered at selected visits: 
• Quality-of-Life (see Appendix 13.3): The Haem-A-QoL Questionnaire, a hemophilia-
specific QoL tool for hemophilia patients who are 17 years old and above, consists of 
46 items covering 10 dimensions to assess a patient’s health-related quality-of-life (von 
Mackensen, 2005). 
• Health Assessment (see Appendix 13.4): The EQ-5D-5L Questionnaire is a simple 
generic measure, containing 5 dimensions (mobility, self-care, usual activities, 
pain/discomfort, and anxiety/depression).  It is a standardized instrument that was 
established by the EuroQol Group, providing a simple descriptive profile and a single 
index value for health status (EuroQol Group, 1990). 

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6.2.5 Health-economic Assessment 
The following information will be captured during the study as part of a health-economic 
assessment: 
a) Number of hospitalizations (excluding pre-planned hospitalizations documented at 
screening) 
b) Number of hospitalization days 
c) Number of emergency room visits 
d) Number of physician visits, excluding study visits 
e) Number of days off school or work 
6.2.6 Archived Bio-samples 
At each time-point where samples are collected for FVIII activity, spare plasma will also be 
collected.  Samples will be archived for testing (if required) of immunology, further coagulation 
assays, future research, or for clarification of any clinical or laboratory AEs.   If a participant 
provides consent, samples may be used for genetic analyses.  
6.3 
Clinical Procedures 
The clinical procedures that will be conducted during this study related to the evaluation of population 
demographics and safety are provided in Table 1. 
Table 1 
Clinical Procedures: Safety and Efficacy Assessments 
Assessment 
Description 
Demographics 
Date of birth, age, sex, ethnicity, and race  
Medical History 
Relevant medical history 
Prior / concomitant therapies within the past 30 days from signing the informed 
consent 
Hemophilia History 
Hemophilia A diagnosis and status: 
• 
Documented date of and age at diagnosis 
• 
FVIII activity level 
• 
Blood type and Rh factor 
• 
FVIII genotype and HLA genotyping 
• 
History of inhibitors to FVIII or allergic reactions to FVIII products 
• 
Bleed history in the past 52 weeks 
• 
Previous FVIII therapy in the past 52 weeks 
Pharmacokinetic Profile 
Current FVIII product.  
• 
Recovery (Cmax following a known IU/kg dose of FVIII)  
• 
Half-life calculations  
Joint Assessments 
Target joint assessment: 
• 
Location of target joint(s) 
• 
Location of joint bleeding 
• 
Frequency of bleed per joint 
• 
Target joint history in the past 26 weeks 
HJHS 

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Assessment 
Description 
Physical Exam 
Full physical examination 
• 
Hemophilic arthropathy assessment  
Height and body weight 
Vital Signs 
Blood pressure (systolic and diastolic) 
Respiratory rate  
Pulse rate 
Temporal or oral temperature (oC) 
ECG 
ECG 
Quality of Life 
Questionnaires 
Haem-A-QoL 
EQ-5D-5L 
Activity Assessments and 
Health Economics 
Hemophilia Activities List 
Health Economic Assessment 
Review of Adverse Events 
and Concomitant 
Therapies/Procedures 
Review of adverse events and concomitant therapies/procedures throughout the 
study 
Hematology (CL, LL) 
WBC count with Differential 
o 
Neutrophils 
o 
Lymphocytes 
o 
Monocytes 
o 
Eosinophils 
o 
Basophils 
o 
ANC (screening Only) 
RBC 
o 
Hemoglobin 
o 
Hematocrit 
o 
Platelet count 
Clinical Chemistry (CL) 
• 
Sodium 
• 
Potassium 
• 
Chloride 
• 
Bicarbonate 
• 
Glucose 
• 
Phosphate 
• 
Serum creatinine 
• 
BUN 
Liver Fibrosis Diagnostic 
Test 
• 
FibroScan (LL)  
• 
FibroTest/FibroSURE (CL)  
o 
Apolipoprotein A1 
o 
Alpha 2 macroglobulin 
o 
Haptoglobin 
• 
AST-to-platelet ratio (LL)  
• 
Liver ultrasound 
• 
α-fetoprotein (CL) 
Urinalysis (CL) 
• 
pH 
• 
Glucose 
• 
Protein 
• 
Blood 
• 
Ketones 
Liver Function Tests and 
CRP (CL and LL) 
• 
Albumin,  
• 
Total bilirubin 
• 
Direct bilirubin 
• 
Indirect bilirubin 
• 
ALP 
• 
AST 
• 
ALT 
• 
Total protein 
• 
GGT 
• 
LDH 
• 
CRP 
Coagulation  
(CL, LL as noted) 
• 
FVIII activity, aPTT (CL and LL) 
• 
FVIII antigen (CL) 
• 
FVIII inhibitor (Nijmegen Bethesda) (CL; LL only at screening), VWF 
antigen (CL), VWF activity (CL) 
• 
Spare plasma (CL) 

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Assessment 
Description 
Neutralizing Antibody (CL) 
rAAV-
 neutralizing antibody 
Immunology (CL) 
• 
Immun PBMC for ELISpot 
• 
Immun PBMC for Inflamm 
Immune Profiling (CL) 
• 
Inflammatory profiling of plasma after vector administration 
o 
Cytokine/Chemokine analysis 
o 
Tryptophan metabolites 
o 
Complement activation 
PAX Gene (CL) 
• 
PAX Gene (RNA) 
Vector Shedding (CL) 
• 
PBMC 
• 
Urine 
• 
Saliva 
• 
Semen 
• 
Serum 
Hepatitis (CL) 
• 
Hepatitis B surface 
antigen 
• 
Hepatitis B core 
antibody total 
• 
HCV antibody 
• 
HCV RNA 
Ampliprep Taqman 
2.0 
• 
HBV DNA 
Ampliprep Taqman 
2.0 
 
HIV Serology (CL) 
HIV-1/HIV-2 antibody and antigen screen 
Viral Load and CD4+ (CL) 
HIV-1/HIV-2 qualitative RNA, CD4+ count  
TPMT (LL) 
TPMT activity or genotype 
Lipid Profile (CL, LL) 
Lipid profile (total cholesterol, LDL, VLDL, HDL, triglycerides) 
TB Testing (LL) 
Tuberculosis Interferon-gamma Release Assay 
SARS-CoV2 Testing (LL) 
Anti-SARS-CoV2 serology  
NAAT for infection with SARS-CoV2 
Fibrinogen (LL) 
Fibrinogen antigen, D-dimer, thrombin time 
ALP = alkaline phosphatase, ALT = alanine aminotransferase, ANC = absolute neutrophil count, aPTT = 
activated partial thromboplastin time, AST = aspartate aminotransferase, BUN = blood urea nitrogen, CL = 
central lab (as per Laboratory Manual), CD4+ = cluster of differentiation 4, Cmax = maximum drug 
concentration, CRP = C-reactive protein, ECG = electrocardiogram, ELISpot = enzyme-linked immunospot 
assay, EQ-5D-5L = EuroQol- 5 Dimension 5 Level, FVIII = coagulation factor VIII, GGT = gamma-glutamyl 
transferase, Haem-A-QoL = Haemophilia A Quality of Life, HBV = hepatitis B virus, HCV = hepatitis C virus, 
HDL = high-density lipoprotein, HIV = human immunodeficiency virus,  HJHS = Hemophilia Joint Health Score, 
HLA = human leukocyte antigen, LDH = lactate dehydrogenase, LDL = low-density lipoprotein, LL = local lab, 
NAAT = nucleic acid amplification testing, PBMC = peripheral blood mononuclear cells, rAAV = recombinant 
adeno-associated viral vector, RBC = red blood cell, SARS-CoV2 = severe acute respiratory syndrome 
coronavirus 2, TB = tuberculosis, TPMT = thiopurine methyltransferase, VLDL = very low-density lipoprotein, 
VWF = von Willerbrand Factor, WBC = white blood cell 
6.4 
Screening Period 
All participants must provide written informed consent before any study-specific procedures or 
assessments are performed.  At the time of consent, participants will be enrolled into the study.  
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 
CCI

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participants screened and to confirm eligibility or record reasons for screening failure, as 
applicable.  
Immunosuppressive therapy may enhance adverse/toxic effects of live vaccines and may diminish 
the effect of inactivated vaccines. Due to the potential that trial participants may receive an 
immunosuppressive medication during the SPK-8011-101 trial, it is suggested that the investigator 
and participant review and complete all age-appropriate vaccinations during the screening period 
and at least 4 weeks prior to planned day of administration of SPK-8011.  
Anti-SARS-CoV2 serology testing will be conducted at screening and at Week 18. This result will 
be informative only and does not affect trial Inclusion/Exclusion. Multiple effects of COVID-19 
on the hemostatic system have been described, including the development of anti-phospholipid 
antibodies (Lupus-like anticoagulants), which might confound interpretation of one-stage clotting 
factor VIII assays.  
6.4.1 Screening Assessments 
The following procedures will be performed during the screening, which may occur over a period 
up to 16 weeks: 
• Obtain written informed consent 
• Review inclusion/exclusion criteria 
• Review prior and concomitant therapies/procedures 
• Record AEs 
• Record information on demographic and baseline characteristics  
• Record medical history and hemophilia history, including FVIII treatment history and 
bleeding history 
• Record target Joints, HJHS, and joint health assessment – May be done between 
screening and prior to Day 0 
• Measure vital signs (blood pressure, pulse, respiratory rate, and oral/temporal 
temperature) 
• Perform physical examination, including height and weight 
• Haem-A-QoL, EQ-5D-5L, Hemophilia Activities List, Health Economic Assessment 
– May be done between screening and prior to Day 0 
• Obtain samples for central laboratory evaluation, unless otherwise noted: 
o Hematology 
o Clinical chemistry 
o α-fetoprotein 
o Vector shedding (PBMC, serum, saliva, urine, semen) – May be done between 
screening and Day 0 
o Spare plasma 
o AAV neutralizing antibody 
o HBsAg, anti-HBc, HBV-DNA  
o HCV-RNA load assay 

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o HIV-1/HIV-2 antigen/antibody 
o Urinalysis  
o Coagulation: 
 aPTT, FVIII activity, FVIII inhibitor (local and central labs) 
 FVIII antigen, VWF activity, VWF antigen 
o Liver function and CRP tests (local and central lab) 
o Liver fibrosis diagnostic test, i.e., FibroScan, FibroTest/FibroSURE, or AST-
to-Platelet Ratio Index (for participants without known pre-existing diagnosis 
of portal hypertension, splenomegaly, or hepatic encephalopathy) (local lab or 
central lab) 
o Fibrinogen (local lab) 
 Antigen 
 D-dimer 
 Thrombin time  
o Thiopurine methyltransferase (TPMT) (local lab)  
o TB Interferon-gamma Release Assay (local lab) 
o Anti-SARS-CoV2 serology (local lab) 
• If indicated: 
o HIV-1/HIV-2 viral load and CD4+ T cell count (for participants who are HIV-
positive), (central lab), 
o Liver ultrasound (“if indicated" means "if, in the judgment of the investigating site 
or the Sponsor, the liver ultrasound is indicated to aid interpretation of the 
screening evaluation of liver fibrosis”.) 
o Electrocardiogram (ECG) (for participant > 50 years of age, or if clinically 
indicated) 
o Lipid 
panel 
(for 
participants 
with 
a 
history 
of 
dyslipidemia 
or 
hypercholesterolemia, or if clinically indicated) (central lab) 
o FVIII genotyping and HLA genotyping (optional sample if genotype is unknown)* 
• Dispense and train on FVIII Infusion Log – May be done at screening or Day 0 (prior 
to vector infusion) 
• Provide PK profile using participants current FVIII product. This can be obtained from 
historical values if available and must include recovery (Cmax following a known 
IU/kg dose of FVIII) and half-life calculations. Population PK analysis using 2-4 
samples is acceptable. If this is not available on the current FVIII product, the 
participant must undergo a PK analysis locally at Screening or Day 0 – May be done 
between screening and Day 0  
*For participants, whose FVIII genotype is unknown, a sample may be drawn for analysis at 
screening.  This is not an inclusion or exclusion criterion; the participant’s refusal to have this 
FVIII genotype sample taken would not exclude the participant from the study unless the severity 
of the disease is otherwise unable to be verified. FVIII genotyping may provide information 
regarding the predisposition of genotypic subpopulations to experience different bleeding 
frequencies and/or to experience different immunologic responses to FVIII following gene 
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6.5 
 Three to Seven Days Prior to Day 0 Assessments 
Laboratory assessment should occur within 3 to 7 days prior to Day 0 for Cohort 2. Results must 
be consistent with inclusion/exclusion criteria.  
• 
Liver function test, CRP (local lab)  
• 
Hematology (local lab)   
• 
Immunology (central lab)  
• 
Immune profiling (central lab)  
• 
PAX gene (RNA) (central lab)  
• 
SARS-CoV2 NAAT testing (local lab) 
 
At the discretion of the investigator, NAAT for infection with SARS-CoV2 (the infectious agent 
in COVID-19) may be performed at this time for asymptomatic individuals. NAAT testing should 
be performed at this time for individuals with any of the following symptoms: cough, shortness of 
breath or difficulty breathing, fever, chills, sore throat, new loss of taste or smell; new 
persistent/recurrent muscle pain or headache. Note: The Infectious Disease Society of America 
panel suggests collecting nasopharyngeal, or mid-turbinate or nasal swabs rather than 
oropharyngeal swabs or saliva alone for SARS-CoV2 RNA testing in symptomatic individuals 
with URTI or ILI suspected of having COVID-19. 
The participants in Cohort 1 should be contacted prior to 
 to verify no changes in the general 
health status and that laboratory assessments collected prior to MMF dosing are consistent with 
inclusion/exclusion criteria, and to confirm the prescribed MMF regimen. 
6.6 
Day -2 
On Day -2, participants in Cohort 1 will begin taking oral MMF 
. 
 
6.7 
Dosing Day Assessments (Days 0, 1) 
If a participant has a bleeding event between the screening period and the start of Day 0, he should 
be treated with his previous FVIII product. All bleeding events and related treatment should be 
recorded in the electronic case report form (eCRF).   
All participants will administer a prophylactic infusion of 50 IU/kg of their current FVIII 
concentrate the morning of Day 0. This can be self-administered and recorded in the participant’s 
Infusion Log.  Supervision from the site staff is permitted.  
Cohort 2 only: On Day 0, participants in Cohort 2 will receive a dose of
 
 
  
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All participants will be infused with a single IV infusion of SPK-8011 at the vector-administration 
center.  The complete dose of SPK-8011 will be infused via infusion pump over approximately 60 
(±2) min.   
6.7.1 FVIII Dosing 
• Verify the administration (self-infused or assisted by site staff) of a single bolus of 50 
IU/kg of FVIII product the morning of 
 or prior to TCZ in Cohort 2. 
6.7.2 Tocilizumab (TCZ) Dosing 
• Verify no changes in the general health status, and that laboratory assessments 
collected up to 1 week prior to TCZ dosing are consistent with inclusion/exclusion 
criteria. 
6.7.3 Vector Dosing 
Assessments before SPK-8011 Vector infusion: 
• Review inclusion/exclusion criteria 
• Measure vital signs (blood pressure, pulse, respiratory rate, and oral/temporal 
temperature)  
• Perform physical examination, including weight 
• Obtain samples for central laboratory evaluation, unless otherwise noted: 
o Coagulation: 
 aPTT and FVIII Activity (local and central labs) 
 FVIII antigen 
o Immunology  
o Immune profiling 
o PAX gene (RNA) 
• Record AEs and concomitant therapies/procedures  
Assessments during Vector infusion: 
• Administer a single IV infusion of SPK-8011 via infusion pump over approximately 
60 (±2) min 
• Record AEs and concomitant therapies/procedures 
Assessments after completion of Vector infusion: 
• Vital signs immediately following the infusion (±2 min), and 2 hours (±10 min) after 
the end of vector infusion 
• Obtain blood samples for central laboratory evaluation from the completion of the 
vector infusion: 
o Immune profiling at 30 (±2) min, 2 hours (±10 min), and 5 hours (±10 min) 
o PAX gene (RNA) at 5 hours (±10 min) 
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• Record AEs and concomitant therapies/procedures 
6.7.4 Day 1 
Measure vital signs 24 (±1) hours post-SPK-8011 dose (blood pressure, pulse, respiratory rate, and 
oral/temporal temperature)  
Obtain blood samples for central laboratory evaluation at all visits, unless otherwise noted: 
• Immunology  
• Immune profiling (24 (±1) hours post vector infusion) 
• PAX gene (24 (±1) hours post vector infusion) 
• Hematology (local and central labs) 
• Coagulation (aPTT and FVIII activity (local and central labs), FVIII antigen)  
• Liver function tests and CRP (local and central labs) 
• Spare plasma 
• Record AEs and concomitant therapies/procedures 
6.8 
Follow-up Observation Period (Weeks 1-52) 
Visits during the follow-up period may occur at either the vector-administration or follow-up 
center.  Any visit requiring a physical exam must be performed at the study center. All other visits 
without a physical exam may be performed by a qualified in-home service provider. 
U.S. Centers for Disease Control and Prevention (CDC) guidance on hygiene, travel, and social 
interactions will be considered by the investigator and sponsor to minimize the risk of community 
acquired viral infections. This may include recommending a shelter in place and/or other social 
distancing measures during immunomodulation. Guidance for Industry, Investigators, and 
Institutional Review Boards on Conduct of Clinical Trials of Medical Products during COVID-19 
Pandemic (U.S. Food and Drug Administration, 2020) will provide considerations to assist in 
assuring the safety of trial participants. International and local health guidelines may be observed 
for sites outside of the United States. 
6.8.1 
Weeks 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 (±2 days) 
A minimum of twice weekly visits are required from Weeks 1-11 to monitor for a potential rise in 
hepatic transaminases and/or loss of FVIII transgene expression. Visits at Weeks 1-11B may be 
performed by an in-home service provider. Visits will occur every 2 weeks from Weeks 12-16. 
If an apparent immune response/liver inflammation is observed and triggers the initiation of 
reactive corticosteroids, please collect additional samples for immune profiling and PAX gene 
prior to corticosteroid administration, if possible (see Schedule of Events and Section 4.1.3.1). 
If immunomodulation is initiated, weekly visits should continue to monitor transaminases, FVIII 
(local and central lab), and ELISpot. Weekly hematology and monthly lipid profile results should 
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altered based on clinical response. Social distancing may be recommended for the duration of 
immunomodulation. 
The following procedures will be performed at all visits unless otherwise noted: 
• Perform physical examination, including weight (Weeks 1A, 7A, 12) 
• Measure vital signs (Weeks 1A, 7A, 12, 14, 16) 
• Hemophilia Activities List, Health Economic Assessment (Weeks 7A, 12, 14) 
• Review FVIII Infusion Log (Weeks 7A, 12, 14) 
• Obtain samples for central laboratory evaluation at all visits, unless otherwise noted: 
o Coagulation 
 aPTT, FVIII activity (local and central labs)  
 FVIII antigen (central lab) 
o Liver function tests and CRP (local and central labs) 
o Hematology (Weeks 1A, 7A, 12, 14, 16) (local and central labs) 
o Clinical chemistry (Weeks 1A, 7A, 12) 
o HBsAg, anti-HBc (Week 12) 
o AAV neutralizing antibody (Weeks 1A, 2A, 4A, 7A, 12, 14) 
o Immunology (Weeks 1-11A, 12, 14, 16) 
o Immune profiling (Weeks 1-4B, 8B, 16) 
o PAX gene (RNA) (Weeks 2B, 4B, 8B) 
o Spare plasma (Week 12) 
o Vector shedding samples (PBMC, serum, saliva, urine, semen) 
 NOTE: Vector shedding samples are collected only until the results of 
3 consecutive samples are negative and received by the investigator 
• Fibrinogen (Weeks 2A, 4A) (local lab) 
o Fibrinogen antigen 
o D-dimer 
o Thrombin time 
• Record AEs and concomitant therapies/procedures 
6.8.2 Weeks 18, 22, 26, 30, 34, 40, 46, 52/End of Study (±2 weeks) 
Visits will occur every 4 weeks from Weeks 18-34, then every 6 weeks from Weeks 40-52/ EOS. 
If immunomodulation is initiated, weekly visits should continue to monitor transaminases, FVIII, 
and ELISpot. Hematology and lipid profile results should also be monitored regularly for Cohorts 
1 and 2 until MMF or TCZ dosing has stopped. This can be altered based on clinical response.  
The following procedures will be performed at all visits unless otherwise noted: 
• Perform physical examination, including weight (Weeks 18, 26, 34, 40, 52/EOS) 
• Measure vital signs 
• Perform liver ultrasound (Week 52 – if indicated) 
• Record target joints, joint health assessment, HJHS (Weeks 26, 52/EOS) 

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• Hemophilia Activities List, Health Economic Assessment (Weeks 26, 40, 52/EOS) 
• Haem-A-QoL, EQ-5D-5L (Weeks 26, 52/EOS) 
• Review FVIII Infusion Log (Weeks 26, 40, 52/EOS) 
• Obtain samples for central laboratory evaluation, unless otherwise noted: 
o Coagulation: 
 aPTT, FVIII activity (local and central labs)  
 FVIII antigen 
 FVIII inhibitor, VWF activity, VWF antigen (Week 52/EOS only) 
o Liver function tests and CRP (local and central labs) 
o Immunology 
o Lipid panel (Week 52/EOS Only) 
o Vector shedding samples (PBMC, serum, saliva, urine, semen) 
 NOTE: Vector shedding samples are collected only until 3 consecutive 
samples are negative 
o Hematology (Weeks 18, 26, 52/EOS)  
o Clinical chemistry (Weeks 18, 26, 52/EOS) 
o AAV neutralizing antibody (Weeks 26, 40, 52/EOS) 
o Spare plasma (Weeks 26, 40, 52/EOS) 
o Urinalysis (Weeks 26, 52/EOS) 
o Anti SARS-CoV2 serology (Week 18)(local lab) 
o α-fetoprotein (Week 52/EOS) 
• Record AEs and concomitant therapies/procedures 
Week 52 procedures are to be performed only at the EOS Visit.  If LTFU study is not open at the 
clinical site at the time of a participant’s planned Week 52 visit, the participant may remain in 
Study SPK-8011-101. The procedures from Week 46, except for collection of immunology 
samples for ELISpot, will be performed at Week 52 and every 12 weeks until the LTFU study is 
open. At that time, the Week 52/EOS visit should occur.  
 

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7 
STUDY INTERVENTION 
7.1 
Description of Study Drug 
Study Drug Name: 
SPK-8011 
Formulation (including dosage 
form and strength): 
 
 
Route of Administration: 
IV infusion 
Packaging and Labeling: 
 
 
  
Study drug will be labeled as required per country 
requirements. 
 
  
Refer to the most recent version of the Investigator and Pharmacy Brochures for further details on 
the study drug. 
7.2 
Study Doses 
The proposed SPK-8011 doses for this study:  
• Starting dose (5x1011 vg/kg)  
• Middle dose (1x1012 vg/kg) 
• High dose (2x1012 vg/kg) 
• Intermediate Dose (1.5 x1012 vg/kg)     
After escalation through the first 3 planned dose levels, an intermediate dose level (e.g., 
1.5x1012 vg/kg of SPK-8011), was agreed with the DMC Any decision to add an intermediate dose 
level or further expand one of the existing protocol-defined dose levels will be made in 
consultation with the DMC. 
Once at least 2 participants of a given dose level complete 6 weeks of safety evaluation and the 
safety data have been reviewed by the DMC without any safety concern, then the first participant 
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at the next dose level can be infused with SPK-8011.  Dosage for each participant will be calculated 
according to the dose calculation worksheet and verified by the Sponsor. Weight obtained at 
screening may be used for dose calculations. 
For participants with body mass index (BMI) exceeding 30 kg/m2, the study dose will be calculated 
based on an alternative body weight determination that assumes a maximum permissible BMI of 
30 kg/m2.  For example, a participant who is 6’2” and weighs 370 pounds (BMI 47.5 kg/m2) would 
receive a vector dose based on an alternative body weight of 234 pounds (which is the body weight 
associated with a BMI of 30 kg/m2 for a 6’2” individual). 
7.3 
Dose Schedule and Administration 
Refer to Figure 1 for a description of the sequence of enrollment. In Cohort 1, oral MMF will be 
self-administered by the participant starting on 
 per the product insert. On Day 0, the 
participant will prophylactically infuse 50 IU/kg of the participant’s usual FVIII protein product 
per the product insert.  In Cohort 2, this infusion of FVIII protein will occur first 
 
 per the product insert. For both cohorts, after these steps, the participant will be 
infused with SPK-8011 intravenously over approximately 60 (±2) min via infusion pump. 
7.4 
Treatment Compliance 
Compliance with the infusion of FVIII protein product and SPK-8011 on the morning of Day 0 
will be verified and recorded by trained site staff. 
Participants will self-infuse with 50 IU/kg of their usual FVIII protein product per the product 
insert. Supervision from the site staff is permitted.  Number of vials, total volume, and total dosage 
are monitored and recorded by the site staff.   
Participants in Cohort 1 will initiate MMF approximately 48 hours prior to 
 The time of 
administration will be monitored and recorded by the site staff. Participants in Cohort 2 will be 
infused with 
 via an infusion pump and will be supervised by the study staff. The lot 
number, total volume infused, and infusion time are monitored and recorded by the site staff.   
After the infusion of FVIII protein product and at least 4 hours (and up to 24 hours) after TCZ 
(Cohort 2 only) participants will be infused with SPK-8011 
.  SPK-8011 will be infused 
via infusion pump and will be supervised by the investigational staff.  The lot number, total volume 
infused, and infusion time are monitored and recorded by the site staff.  Therefore, full compliance 
with SPK-8011 infusion is anticipated. 
7.5 
Study Drug Storage 
SPK-8011 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.    
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7.6 
Study Drug Preparation, Handling and Disposal 
7.6.1 Study Drug Preparation 
Prior to preparing the study drug, the responsible pharmacy staff should first carefully review the 
instructions provided in the Pharmacy Brochure.  The investigational pharmacy personnel 
preparing the study drug for infusion will use universal precautions and appropriate personal 
protective equipment. The dilution will be performed using aseptic techniques in a biosafety 
cabinet.  Just prior to use, the frozen product will be thawed at room temperature and diluted 
according to the verified dose calculation worksheet.  Once the vials are diluted, SPK-8011 will 
be stored at room temperature and infusion must be initiated within 6 hours of thawing to assure 
maximum potency.  
7.6.2 Study Drug Handling and Disposal 
The investigator or designee must confirm appropriate temperature conditions have been 
maintained during transit for all study drug received and any discrepancies are reported and 
resolved before use of the study drug. Immediately after receipt, the study drug should be stored 
as described in Section 7.5. 
Only participants enrolled in the study may receive study drug and only a trained and authorized 
site staff may supply or administer the IMP. Study drug must only be thawed after confirmation 
that the participant is eligible, and the appropriate washout period was met, if applicable. Vials are 
for single use only.  
The site should store all used and unused vials of SPK-8011, as instructed by the Sponsor and as 
per the institution’s procedures.  
7.6.3 Accountability and Destruction 
The investigator, institution, or the head of the medical institution (where applicable) is responsible 
for study drug accountability, reconciliation, and record maintenance (i.e., receipt, reconciliation, 
and final disposition records). 
All vials, both used and unused, must be retained for monitoring and study drug accountability. At 
study completion, reconciliation must be made between the amount of study drug supplied, 
dispensed, and subsequently destroyed or returned to the Sponsor, or its designee.   
Further guidance and information for the final disposition of used/unused study drug are provided 
in the Pharmacy Binder.  
7.7 
Labeling 
The product label includes: Investigational product name; manufacturer; specific lot number; date 
of manufacture; vial number; storage instructions; and investigational product warning. The 
Pharmacy Brochure will contain copies of approved labels.  

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7.8 
Study Compliance 
Following the administration of SPK-8011, participants will be followed according to the protocol 
Schedule of Events.  Participants will be encouraged to follow-up completely and according to 
study endpoints.  Non-adherence to the protocol will be reported to the relevant regulatory groups 
overseeing the study. 
7.9 
Prior and Concomitant Medications 
The use of concomitant therapies or procedures, as defined below, must be recorded on the 
participant’s eCRF.  AEs related to administration of these therapies or procedures must be 
documented on the appropriate eCRF. 
7.9.1 Concomitant Therapy 
Any medication or vaccine (including over-the-counter or prescription medicines, vitamins, and/or 
herbal supplements) that the participant is receiving 30 days prior to screening, at the time of 
enrollment or receives during the study must be recorded in the eCRF along with: 
• Reason for use 
• Dates of administration including start and end dates 
• Dosage information including dose and frequency 
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.  Any dose change during the study must be documented in the 
participant’s record and eCRF. Investigator or designee should review the list of all current 
medications, over the counter medications, vitamins, and herbal supplements. Any concomitant 
medication that has known hepatotoxicity should be discontinued in the first 12 weeks following 
vector infusion. 
The Medical Monitor should be contacted if there are any questions regarding concomitant or prior 
therapy. 
7.9.2 Permitted Therapy 
During the study, participants are requested to suspend their prophylaxis regimen, but participants 
are permitted to take: 
• FVIII product, as needed for bleeding.  Usage of clotting factors (product, date, dosage, 
reason) will be recorded in the Infusion Log.  
• Non-steroidal anti-inflammatory drugs, except for ibuprofen and acetylsalicylic acid 
(aspirin). 
Participants should be instructed to discuss any new medications, including non-prescription drugs 
and herbal preparations, with the Investigator prior to taking them.  

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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.  
The CDC recommends a limit of 2 alcoholic drinks per day or fewer for adult males. While this is 
a general guideline, the sponsor recommends not having any alcohol drinks during the first 12 
weeks after infusion of the study product. Alcohol has the potential to inflame the liver, which 
may make it difficult to monitor the status of the health of your liver and has the potential to 
interact negatively with the study product or other medications. 
7.9.3 Prohibited Therapy 
The following concomitant medications are not permitted during the study: 
• Acetylsalicylic acid (aspirin) or ibuprofen; however, other non-steroidal anti-
inflammatory drugs are permitted. 
• Routine prophylactic treatment with FVIII product after Day 14 post vector infusion 
unless clinically indicated and in discussion with the investigator and/or sponsor. 
• Routine prophylactic treatment with emicizumab is prohibited unless clinically 
indicated and in discussion with the investigator and sponsor 
• Any other investigational therapies prior to screen as defined in the exclusion criteria 
or used during the study 
Any concomitant medication that has known hepatotoxicity should be discontinued in the first 12 
weeks following vector infusion. If a medication with known liver toxicity cannot be avoided, the 
investigator should discuss it with the Sponsor.  
7.9.4 Concomitant Procedures 
A concomitant procedure is any therapeutic intervention (e.g., surgery/biopsy, physical therapy, 
tooth extraction) or diagnostic assessment (e.g., blood gas measurement, bacterial cultures) 
performed between the time the participant is enrolled (at screening) and last study visit (Week 
52/EOS). The use of concomitant procedures must be recorded in the eCRF. 
 
 

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8 
DISCONTINUATION OF STUDY INTERVENTION AND 
PARTICIPANT DISCONTINUATION/WITHDRAWAL 
8.1 
Participant Discontinuation/Withdrawal from the Study 
Participants may withdraw from the study at any time at his own request or may be withdrawn at 
any time at the discretion of the investigator for safety, behavioral, compliance, or administrative 
reasons. 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 and also withdraws consent for disclosure of future information, the 
Sponsor may retain and continue to use any data collected before such withdrawal of consent.  
The investigator should record the reason and date of withdrawal in the eCRF and in the 
participant’s medical records. If possible, the participant should confirm his decision in writing. 
A participant may permanently withdraw from the study at any time. An investigator and the 
Sponsor may permanently remove a participant from the study at their discretion for any of the 
following reasons: 
• The participant withdraws consent.   
• At the discretion of the Investigator for medical reasons. 
• At the discretion of the Investigator or Sponsor for non-compliance. 
• The participant is unwilling or unable to attend study visits and undergo safety 
assessments as per the protocol. 
If a participant withdraws from the study after enrollment, but before receiving a dose of the study 
drug (SPK-8011), then follow-up beyond the screening evaluations is not required.  Withdrawn 
participants that did not receive a dose of the study product will be replaced. 
8.2 
Early Termination Study Visit 
If the participant withdraws after receiving the investigational product, the study procedures to be 
done should be identical to those of the EOS visit.  If the participant withdraws before receiving 
the investigational product, early termination study procedures are not necessary (see the Schedule 
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9 
ADVERSE EVENTS AND SERIOUS ADVERSE EVENTS 
The definitions of an AE or SAE can be found below. 
An 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 for pursuing 
follow-up information for AEs that are serious, considered related to the study intervention or 
study procedures, or that caused the participant to discontinue the study (see Section 8). 
9.1 
Definitions 
9.1.1 Adverse Event 
An AE is any untoward medical occurrence in a patient or clinical investigation participant 
administered a pharmaceutical product and which does not necessarily have a causal relationship 
with this treatment. An AE can therefore be any unfavorable and unintended sign (including an 
abnormal laboratory finding), symptom, or disease temporally associated with the use of a 
medicinal (investigational) product, whether or not related to the medicinal (investigational) 
product.   
All AEs must be documented regardless of causality. 
Events meeting the AE definition include: 
• Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or 
other safety assessments (e.g., ECG, radiological scans, vital signs measurements), 
including those that worsen from baseline, considered clinically significant in the 
medical and scientific judgment of the investigator (i.e., 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 investigational product administration even 
though it may have been present at one time 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 
investigational product 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 perceived efficacy, failure of expected pharmacological action, or similar assessment will 
not necessarily be reported as an AE. Such instances will be captured in the efficacy assessments.  

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However, if signs, symptoms and/or clinical sequelae resulting from lack of efficacy meet the 
definition of an SAE, they will be reported as such. 
Events that do NOT meet the AE definition include: 
• In this population, bleeding episodes are not considered AEs.  All bleeding episodes 
will be captured in the eCRF.  If serious criteria apply (see Section 9.1.2), the event 
should be reported as an SAE 
• 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 (e.g., 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 
or detected at the start of the study that do not worsen. 
9.1.2 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 (e.g., hospitalization for signs/symptoms of the disease under study, death due to 
progression of disease). 
An SAE is defined as any untoward medical occurrence that, at any dose meets the following: 
• Results in death 
• 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. 
• 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 department 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 

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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. 
• Results in persistent or significant 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 (e.g., sprained ankle) which may interfere with or prevent 
everyday life functions but do not constitute a substantial disruption. 
• Is a congenital anomaly/birth defect 
• 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. 
A prescheduled, elective procedure, or a routinely scheduled treatment that requires hospitalization 
is NOT considered to be an SAE; the study site must document all of the following: 
• The prescheduled, or elective procedure, or routinely scheduled treatment was 
scheduled (or was on a waiting list to be scheduled) prior to obtaining the participant’s 
consent to participate in the study. 
• The condition requiring the prescheduled, or elective procedure, or routinely scheduled 
treatment was present before and did not worsen or progress, in the opinion of the 
Investigator, between the participant’s consent to participate in the study and the time 
of the procedure or treatment. The prescheduled, or elective procedure, or routinely 
scheduled treatment is the sole reason for the intervention or hospital admission. 
9.1.3 Adverse Events of Special Interest (AESI) 
There are several AEs that will be monitored closely as adverse events of special interest (AESIs) 
to enable an adequate risk-benefit evaluation of SPK-8011 versus standard therapy during the 
study and additional data may be requested for these events. The AESIs are: 
• AEs associated with FVIII inhibitor formation 
• The development, in any participant, of SPK-8011 related Grade IV (> 10 x ULN) 
elevated transaminases  

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• The development, in any participant, of SPK-8011 related Grade I or higher (≥ 2.5x 
ULN) elevated hepatic transaminases that fails to resolve to less than 2.5x ULN within 
4 weeks with immunomodulatory agents 
• Any occurrence of a malignancy at any point after vector infusion that is related to 
SPK-8011 or one of the immune modulating agents 
• Thrombotic and/or embolic events (TEE) 
9.2 
Recording and Follow-Up of AE and/or SAE 
When an AE/SAE occurs, it is the responsibility of the investigator to review all documentation 
(e.g., 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 sponsor/designee in lieu of completion of the AE/SAE CRF page. 
• There may be instances when copies of medical records for certain cases are requested 
by sponsor/designee.  In this case, all participant identifiers, with the exception of the 
participant number, will be redacted on all copies of the medical records before 
submission to sponsor/designee. 
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. 
9.3 
Safety Classifications 
9.3.1 Assessment of Intensity 
The investigator will make an assessment of intensity for each AE and SAE reported during the 
study and assign it to 1 of the following categories: 
• Mild: An event that is easily tolerated by the participant, causing minimal discomfort 
and not interfering with everyday activities. 
• Moderate: An event that causes sufficient discomfort and interferes with normal 
everyday activities. 
• Severe: An event that prevents normal everyday activities. An AE that is assessed as 
severe should not be confused with an SAE. Severe is a category utilized for rating the 
intensity of an event; and both AEs and SAEs can be assessed as severe. 
An event is defined as ‘serious’ when it meets at least 1 of the predefined outcomes as described 
in the definition of an SAE, NOT when it is rated as severe.  
Other measures to evaluate AEs and SAEs (especially for abnormal laboratory changes) may be 
utilized (e.g., National Cancer Institute Common Terminology Criteria for Adverse Events [NCI-
CTCAE v5.0]). 

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9.3.2 
Assessment of Causality 
The investigator is obligated to assess the relationship between investigational product (or 
administration procedure or study required concomitant therapy) and occurrence of each AE/SAE. 
The causality assessment is one of the criteria used when determining regulatory reporting 
requirements. The causality assessment will be categorized either as: 
• Related – there are facts (evidence) or arguments to suggest a "reasonable possibility" 
for a causal relationship between the investigational product and the event. 
• Not Related – there is no reasonable temporal sequence or known pattern of response 
after administration of the investigational product and/or the AE could have been 
produced by the participant’s clinical state, environmental or toxic factors, or other 
therapy administered to the participant. 
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 investigational product 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 Spark or designee. However, it is very important that 
the investigator always make an assessment of causality for every event before the initial 
transmission of the SAE data to Spark or designee. 
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. 
9.4 
Follow-up and Reporting Requirements 
9.4.1 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. All SAEs will be followed until resolution, 
stabilization, the event is otherwise explained, or the participant is lost to follow-up. 
• 
New or updated information will be recorded in the originally completed CRF. 
The investigator will submit any updated SAE data to the sponsor within 24 hours of receipt of 
the information. 

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9.4.2 Reporting of SAEs 
Reporting to the Sponsor/designee via a SAE report form are as follows:  
• All AEs must be recorded in the CRF in a timely manner. 
• All SAEs must be reported in the SAE report form to the sponsor within 24 hours of 
site awareness via email to Spark@primevigilance.com.  
• In rare circumstances where SAE information is discussed during the phone 
conversation with medical monitor, this SAE information must be documented and 
send it via email to Spark PV at sparkpv@sparktx.com immediately. A copy of the 
SAE report form must be submitted followed by the telephone conversation to SAE 
reporting email address. 
• Initial notification via telephone does not replace the need for the investigator to 
complete and sign the SAE report form pages within the designated reporting time 
frames. 
• Contacts for SAE reporting can be found in the SAE report form 
The minimum reporting requirements for immediate reporting of SAEs include:  
• Participant ID 
• Event description 
• Identifiable reporting source 
• Investigator causality assessment 
9.5 
Time Period and Frequency for Collecting AE and/or SAE Information 
All AEs/SAEs will be collected from the signing of the informed consent form (ICF) until the EOS 
visit at the time points specified in the Schedule of Events. 
Medical occurrences that begin before the start of study intervention but after obtaining informed 
consent will be recorded on the Medical History section of the eCRF not the AE section. 
All SAEs will be recorded and reported to the sponsor or designee within 24 hours, as indicated in 
Section 9.4.2. The investigator will submit any updated SAE data to the sponsor within 24 hours 
of it being available. 
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. 
The method of recording, evaluating, and assessing causality of AE and SAE and the procedures 
for completing and transmitting SAE reports are provided in Section 9.3 and Section 9.4. 

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9.5.1 
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, 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 and sponsor policy and forwarded to 
investigators as necessary. 
• An investigator who receives an investigator safety report describing a SAE or other specific 
safety information (e.g., 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. 
9.5.2 Pregnancy 
Participants participating in this study are exclusively male.  Should a female partner of the 
participant become pregnant during the study, the Investigator must notify Spark within 14 days 
of the investigator becoming aware of the pregnancy. The participant and female partner must sign 
an IRB approved pregnant partner release of medical information/ICF before collecting medical 
information about the pregnancy.  
Whenever possible, and after a pregnant partner’s release of medical information/ICF is signed, a 
pregnancy in a female partner of a male participant exposed to SPK-8011 should be followed to 
term so as to assess any potential occurrence of congenital anomalies or birth defects. Any follow-
up information, including premature termination and the status of the mother and child after 
delivery, should be reported by the investigator to Spark using a Pregnancy Reporting / Outcome 
Form.  
9.6 
Treatment of Overdose 
The chance of overdosing is remote as the SPK-8011 gene therapy product is a one-time 
administration with no participant access to the study drug.  Furthermore, SPK-8011 will be 
prepared by trained pharmacy staff and verified by a trained pharmacist before administration to 
the participant.  Nevertheless, for this study, an overdose is any dose given to a participant that is 
2 X greater than the intended dose of the study drug.  If an AE(s) is associated with (“results from”) 
the overdose, the AE(s) and overdose will be reported as and SAE, even if no other seriousness 
criteria are met.  If the overdose did not result in any associated clinical symptoms or abnormal 
laboratory results, the overdose will be reported as a non-serious AE as “accidental overdose 
without adverse effect”.  All overdoses with and without an AE should be recorded in the eCRF 
and only overdose with associated AEs should be reported in an SAE report form and sent to the 

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Sponsor/designee within 24 hours.  The participant should be monitored and should be treated as 
medically indicated based on their condition. 
In the event of an overdose, the investigator should: 
1. Contact the Medical Monitor immediately. 
2. Closely monitor the participant for any AE/SAE and liver function test (LFT) 
abnormalities. LFT abnormalities should be monitored as per protocol and any 
abnormalities should be immediately reported to the Medical Monitor. 
3. Document the quantity of the excess dose as well as the duration of the overdose in the 
CRF. 
 
10 STATISTICAL CONSIDERATIONS 
10.1 
Statistical Hypotheses 
No statistical hypotheses will be tested as part of this protocol.  This study will be used to establish 
an initial safety and efficacy profile of SPK-8011.  
10.2 
Sample Size Determination  
The sample size is based on the need to establish the initial safety and efficacy profile of SPK-
8011.  Up to 50 eligible participants will be dosed.  If more than 50 eligible participants are to be 
dosed, regulator(s) will be informed along with the DMC. 
Because the size of the hemophilia A population is limited (an estimated incidence of 1 in 
5,000 male births), the number of participants available for study is correspondingly limited.  Thus, 
the sample size is based on clinical, rather than statistical, considerations.  
 
10.3 
Analysis Population 
The Full Analysis Set (FAS) is defined as all participants who receive the infusion of SPK-8011. 
The analyses of safety and efficacy will be performed in this population, including the evaluation 
of vector-derived FVIII:C activity levels for estimation of peak and steady-state activity levels. As 
this is an open-label study, additional subgroup analyses may be specified following clinical 
review. 
The Safety Population will include all participants who receive any study-mandated medication 
and will be used to summarize all safety data.  
10.4 
Demography and Baseline Disease Characteristics 
All participants who receive the infusion of SPK-8011 will be included in the analysis of 
demography and baseline disease characteristics. 

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Demographic and other baseline characteristics will be summarized using descriptive statistics.  
Data to be tabulated will include, but not be limited to age, race, medical/hemophilia history, and 
other disease-specific measures.  All data will be summarized by the overall study population and 
by each dose level. 
10.5 
Primary and Secondary Endpoints 
10.5.1 Safety Analysis 
For the analysis of safety, the incidence and severity of AEs will be tabulated.  Changes from 
baseline in clinical laboratory variables (including FVIII inhibitor and laboratory parameters for 
thrombotic potential), vital signs, vector shedding analysis, and physical examination findings will 
be summarized by descriptive statistics.  All AEs will be tabulated by occurrence, grouped by body 
system, and summarized by dose group. The rate of occurrence for each AE will be summarized 
by body system, severity, and relation to the administration of SPK-8011. All SAEs will be 
summarized separately. Physical examination and clinical laboratory value abnormalities will be 
summarized by time point. Values and changes from baseline of key safety parameters (e.g., LFT 
abnormalities) at each time point will be tabulated. Exploratory analysis of safety parameters may 
be done by tabulating transitions from baseline to the EOS visit at Week 52 (e.g., normal to normal, 
normal to abnormal, etc.).  
 
10.5.2 Efficacy Analysis 
Summary statistics will be created by SPK-8011 dose group for the following parameters: 
• The number of bleeding events expressed as the ABR per participant (spontaneous and 
traumatic combined) following SPK-8011 administration and beginning 28 days 
following SPK-8011 administration.  
• Absolute change in ABR for all bleeding events and bleeding events observed 
beginning 28 days following SPK-8011 administration from the hemophilia history-
based ABR for the 52-weeks prior to SPK-8011 administration. 
• Proportion of participants with a post-SPK-8011 administration ABR of 0 or 1 
(separately for all bleeding events and bleeding events reported beginning at least 28 
days following SPK-8011 administration).  
• Number of recorded FVIII infusions per participant (referred to in the protocol as 
annualized FVIII usage) following SPK-8011 administration and beginning 28 days 
following SPK-8011 administration. 
• Absolute change in the number of recorded FVIII infusions following SPK-8011 
administration (all infusions and infusions reported beginning 28 days following SPK-
8011 administration) from the prior 52-week hemophilia history. 

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10.5.3 Pharmacokinetic Analysis 
FVIII:C activity level (one-stage; central lab-recorded) at nominal weeks 4, 8, 12, 16, 20, 24, 28, 
32, 36, 40, 44, 48 and 52 following SPK-8011 administration will be summarized descriptively by 
SPK-8011 dose group. For each participant, the difference between the lab visit date and the SPK-
8011 infusion date will be obtained as the number of days of follow-up. The nominal week of 
follow-up will then be computed as the ceiling value of the number of days of follow-up divided 
by 7. Thus, as an example, nominal week 4 will be assigned to days 22 through 28 of follow-up. 
An average value will then be computed for all recorded data for the 4 nominal weeks up to a 
specific time point as defined above, e.g., the nominal week 16 activity level will be the average 
for all values obtained across nominal weeks 13, 14, 15 and 16. In the event of missing information, 
the available non-missing data will be used in this calculation, e.g., a participant with no calculated 
nominal week 14 FVIII:C value will have the available nominal week 13, 15 and 16 data used to 
estimate the nominal week 16 result. 
Steady-state FVIII:C activity (central lab-recorded) from nominal week 12 through nominal week 
52 following SPK-8011 administration will be summarized descriptively by SPK-8011 dose 
group. Using the same 4-week block construct already identified, an average value for each 
participant across all time points beginning with nominal week 12 will be computed, i.e., the 
average FVIII:C level across the individual participant averages obtained across nominal weeks 
12, 16, 20, 24, 28, 32, 36, 40, 44, 48 and 52. The proportion of participants who maintain a FVIII:C 
activity level ≥ 12% across nominal weeks 12, 16, 20, 24, 28, 32, 36, 40, 44, 48 and 52 will also 
be obtained. Depending on the observed distribution, additional exploratory calculations may be 
performed to evaluate the proportion of participants with a FVIII:C activity level ≥ 12% across, 
for example, at least 9 of these 11 timepoints to account for expected random variability. It is 
expected that corticosteroid therapy will increase the transgene expression from the SPK-8011 
expression cassette; this effect is transient and dose-dependent so that as the corticosteroid is 
tapered and discontinued, the steady state FVIII expression from transduced hepatocytes becomes 
evident (not influenced by concurrent steroids). The assay of the FVIII activity that is measured 
while on corticosteroids (as assayed by one-stage and by chromogenic FVIII activity) appears not 
to be confounded, i.e., while on corticosteroids the observed hemostatic protection afforded by the 
transgene-derived FVIII is consistent with the measured FVIII activity and the increased measured 
level of FVIII is not an assay artifact. In contrast, TCZ is expected not to influence levels of the 
expression of the transgene product, as evaluated in pre-clinical animal studies (summarized in 
Section 2.2.4), and is expected not to have ongoing activity in circulation after Week 12 (the 
timepoint after which the steady state FVIII: C activity is examined). For this reason, the treatment 
effect, i.e., determination of the ultimate steady state FVIII: activity resulting from the SPK-8011 
dose, is not estimated while participants remain on corticosteroid therapy, and is evaluated after 
corticosteroids have been discontinued completely for at least 2-4 weeks. Additionally, the 
evaluation of the peak vector-derived FVIII:C activity may require careful interpretation if the 
participant is receiving corticosteroids at the time of peak activity, whereas TCZ is not expected 
to have direct action on transgene expression and peak FVIII:C activity. One potential outcome at 
the conclusion of the study is that the peak FVIII:C activity may demonstrate a positive association 
with eventual steady state FVIII:C activity for participants who are not receiving reactive 
corticosteroids at time of peak activity (in Cohort 1 and Cohort 2), but may fail to demonstrate an 

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association for participants whose peak FVIII:C activity occurs during concurrent treatment with 
corticosteroids. This potential confounding effect will be considered in the descriptive statistical 
review. 
Vector shedding of SPK-8011 or time to below quantifiable limits (BQL) will be summarized 
descriptively by dose group and by PBMC and bodily fluids. 
10.6 
Exploratory Endpoints Analysis 
All data on the new target joints, hemophilia joint health score, changes in level of activity, 
hemophilia activity list, Haem-A-QoL and EQ-5D-5L questionnaires will be summarized 
descriptively and provided in participant listings.  The questionnaire will be scored according to 
the recommendations of the questionnaire authors.  Each domain score and change from baseline 
in domain score will be summarized by visit.   
 
All data on the joints and health-economic parameters will be summarized for exploratory 
purposes only.  Data will be analyzed according to related recommendations and guidelines.  
Continuous variables will be summarized by descriptive statistics and categorical variables will be 
presented with the number and percentage in each category.  No imputation of data will be 
performed.   
Exploratory inflammatory profiling of plasma and immune function gene expression of PBMC 
after vector administration (ELISpot, and other exploratory biomarkers) will be summarized 
descriptively by SPK-8011 dose group. 
10.7 
Interim Analyses 
Interim analyses may be performed after at least 2 participants from a given dose cohort complete 
Week 12. 
 
 

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11 SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
11.1 
Regulatory, Ethical and Study Oversight Considerations 
The Sponsor and the Investigator(s) will comply with all instructions, regulations, and agreements 
in this protocol, applicable ICH GCP guidelines, and conduct the study according to applicable 
local regulations.  The Sponsor and the Investigator(s) must adhere to the principles set forth by 
the Declaration of Helsinki dated October 2008. 
11.1.1 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 ICH GCP Guidelines 
• Applicable laws and regulations 
• The protocol, protocol amendments, ICF, Investigator Brochure, and other relevant 
documents (e.g., advertisements) must be 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: 
o 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 
o Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures 
o Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR, International Conference on Harmonisation (ICH) 
guidelines, the IRB/IEC, European regulation 536/2014 for clinical studies (if 
applicable), and all other applicable local regulations 
11.1.2 Financial Disclosure 
Investigators and sub-investigators will provide the sponsor with sufficient, accurate financial 
information as requested to allow the sponsor to submit complete and accurate financial 

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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. 
11.1.3 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, International 
Conference on Harmonisation (ICH) guidelines, Health Insurance Portability and 
Accountability Act (HIPAA) requirements, where applicable, and the IRB/IEC or study 
center.  
• 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. 
• Pregnant partners of male participants will be asked to sign a separate ICF for 
pregnancy outcome information.  
11.1.4 
Data Protection 
Prior to any testing under this protocol, including screening tests and assessments, candidates must 
also provide all authorizations required by local law (e.g., Health Insurance Portability and 
Accountability Act (HIPAA) 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.  Participants will be assigned a unique identifier by the 
sponsor. Any participant records or datasets that are transferred to the sponsor will contain the 
identifier only; participant names or any information which would make the participant identifiable 
will not be transferred.  
The participant must be informed that his medical records may be examined by Clinical Quality 
Assurance (CQA) auditors or other authorized personnel appointed by the sponsor, by appropriate 
IRB/IEC members, and by inspectors from regulatory authorities. Every effort will be made to 
keep the participant’s personal medical data confidential. 

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The participant must be informed that his personal study-related data will be used by the sponsor 
in accordance with local data protection law(s). The level of disclosure must also be explained to 
the participant.  
11.1.5 
Committees Structure 
The independent DMC is composed of at least 3 independent experts in hemophilia or 
immunology.  The independent DMC will be responsible for reviewing safety 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.  
11.1.6 
Dissemination of Clinical Study Data 
The Sponsor will register the study and post study results, regardless of outcome, on a publicly 
accessible website (e.g., www.ClinicalTrials.gov), in accordance with the applicable laws and 
regulations. The Sponsor may also provide study information for inclusion in national registries 
according to local regulatory requirements. Results of this study will be disclosed according to the 
relevant regulatory requirements. 
11.1.7 
Data Quality Assurance 
• All participant data relating to the study will be recorded using an electronic CRF unless 
transmitted to the sponsor or designee electronically (e.g., laboratory data). The 
investigator is responsible for verifying that data entries are accurate and correct by signing 
the CRF.  
• The investigator must maintain accurate documentation (source data) that supports the 
information entered in the CRF.   
• The investigator must permit study-related monitoring, audits, IRB/IEC review, and 
regulatory agency inspections and provide direct access to source data documents.  
• 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 period of 2 years following the date a marketing 
application is approved for the drug for the indication for which it is being investigated; or, 
if no application is to be filed or if the application is not approved for such indication, until 
2 years after the investigation is discontinued and FDA is notified; or, for a longer retention 
period if local regulations or institutional policies so require.  No records may be destroyed 

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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.  
11.1.8 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. 
Data 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. 
11.1.9 Study and Site Closure 
Study sites will be closed upon study completion.  Study completion 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.  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 sponsor 
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. 
The Investigator may initiate study-site closure at any time, provided there is reasonable cause 
and sufficient notice given in advance of the intended termination. 
Reasons for the early closure of a study site by the Sponsor or Investigator 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 development 
11.1.10 
Publication Policy 
All study data and intellectual property rights in the results derived from the study are the property 
of the Sponsor.   The Sponsor may utilize the data in various ways, such as submission to 
government regulatory authorities or disclosure to other Investigators.  The Sponsor recognizes 
the right of the Investigator, while free to utilize data derived from the study for scientific purposes 
or publish the results in recognized scientific journals, is subject to the provisions of the Clinical 
Trial Agreement (CTA) upon completion of the study.  
Unless otherwise specified in the CTA, the Investigator’s institution and Investigator(s) shall not 
publish or present data from an individual study center until after publication of the results of the 
complete multicenter study. Subsequent publications must refer to the multicenter findings. The 

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institution and Investigator shall submit reports, abstracts, manuscripts, and/or other presentation 
materials to the Sponsor for review and approval before submission for publication or presentation. 
The Sponsor shall have 30 days in advance of submission to respond with any requested revisions, 
including, without limitation, the deletion of confidential information. The Investigator(s) shall act 
in good faith upon requested revisions, except that Investigator(s) shall delete any confidential 
information from such proposed publication. 
 
 
 

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12 REFERENCES 
1. 
Actemra (tocilizumab) Prescribing Information. (2020). South San Francisco, CA: 
Genentech, Inc. https://www.gene.com/download/pdf/actemra_prescribing.pdf 
2. 
Aledort, L.M., Haschmeyer, R.H., & Pettersson, H. (1994). A longitudinal study of 
orthopaedic outcomes for severe factor-VIII-deficient haemophiliacs. The 
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133. Shahani, T., Covens, K., Lav’nd'homme, R., Jazouli, N., Sokal, E., Peerlinck, K., & 
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146. van Genderen, F.R., van Meeteren, N.L., van der Bom, J.G., Heijnen, L., de Kleijn, P., 
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148. von Mackensen S, Gringeri A, Ravera S. (2005). Validation of the haemophilia-specific 
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13 APPENDIX 
13.1 
Factor VIII Infusion Log 

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13.2 
Hemophilia Activities List and Change in Level of Activity 
 
 

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13.3 
Haem-A-QoL Questionnaire 
 

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13.4 
EQ-5D-5L Questionnaire 
 

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13.5 
Hemophilia Joint Health Score 
 

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13.6 
Abbreviations 
AASLD 
American Association for the Study of Liver Diseases 
AAV 
Adeno-associated virus  
AAV2 
Adeno-associated virus, serotype 2 
AAV5 
Adeno-associated virus, serotype 5 
AAV8 
Adeno-associated virus, serotype 8 
AAVrh10 
Adeno-associated virus, rhesus serotype 10 
AAV-Spark100 
Adeno-associated virus Spark100 vector 
AAV-Spark200 
Adeno-associated virus Spark200 vector 
ABO 
Blood type 
ABR 
Annualized bleeding rate 
AE 
Adverse event  
AFU 
Annualized factor usage 
AIDS 
Acquired immunodeficiency syndrome 
ALP 
Alkaline phosphatase 
ALT 
Alanine aminotransferase 
ANC 
Absolute neutrophil count 
Anti-HBC 
Total hepatitis B core antibody 
aPTT 
Activated partial thromboplastin time 
ARDS 
Acute Respiratory Distress Syndrome 
AST 
Aspartate aminotransferase 
BDD 
B-domain-deleted 
BDD-hFVIII 
B-domain-deleted human factor VIII 
BID 
Twice a day 
BMI 
Body mass index 
BMN-270  
Adeno-associated viral vector, serotype 5, with B-domain-delated human 
factor VIII gene (aka AAV5-BDD-hFVIII) 
bp 
Base pair 
BP 
Blood pressure 
BQL 
Below quantifiable limits 
BU 
Bethesda units  
BUN 
Blood urea nitrogen  
˚C 
Celsius  
CD4+ 
Cluster of differentiation 4 
CD8+ 
Cluster of differentiation 8 
CDC 
U.S. Centers for Disease Control and Prevention 
cDNA 
Complimentary deoxyribonucleic acid 
Cl 
Chlorine 
CNS 
Central nervous system 
COVID-19 
Coronavirus disease caused by SARS-CoV2 
CRF 
Case report form 
CRP 
C-reactive protein 

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CQA 
Clinical Quality Assurance 
CTA 
Clinical trial agreement 
CTCAE 
Common Terminology Criteria for Adverse Events 
CTL 
Cytotoxic T lymphocyte 
DMC 
Data Monitoring Committee 
DNA 
Deoxyribonucleic acid 
ECG 
Electrocardiogram 
CRF/ eCRF  
 Case report form 
ED 
Exposure day 
EHL 
Extended half-life 
ELISpot 
Enzyme-linked immunospot assay 
EQ-5D-5L 
Euro quality-of-life five dimensions questionnaire 
FAS 
Full analysis set 
FDA 
U.S. Food and Drug Administration  
FIX 
Coagulation factor IX 
FIXa 
Activated factor IX 
FK506 
Tacrolimus 
FVIII 
Coagulation factor VIII 
FVIII:C 
Factor VIII in circulation 
FVIII-SQ 
The “SQ” form of B-domain deleted human coagulation factor VIII as 
described by Lind (Lind, 1995) 
FXa 
Activated factor X 
GGT 
Gamma-glutamyl transferase 
GLP 
 
Good Laboratory Practice 
GMP 
Good Manufacturing Practice 
Haem-A-QoL 
 
HBsAg 
Hepatitis B surface antigen 
HBV 
Hepatitis B virus 
HCV 
Hepatitis C virus  
HDL 
High-density lipoprotein 
hFIX 
Human coagulation factor IX 
hFIX39-Padua 
Human coagulation factor IX Padua variant 
hFVIII 
Human coagulation factor VIII 
HIV 
Human immunodeficiency virus  
HJHS 
Hemophilia Joint Health Score 
HLA 
Human leukocyte antigen 
HRQoL 
Health-related quality-of-life 
ICF 
Informed consent form 
ICH 
Intracranial hemorrhage 
ICH GCP 
International Conference on Harmonization Good Clinical Practice 
ID 
Identification 
IEC 
Institutional Ethics Committee 
IFN-γ 
Interferon gamma 

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IgG4 
Immunoglobulin G subclass 4 
IND 
Investigational new drug application  
IRB 
Institutional Review Board 
ITR 
Inverted terminal repeats 
IU 
International units  
IV 
Intravenous 
LDH 
Lactate dehydrogenase  
LDL 
Low-density lipoprotein 
LFT 
Liver function test 
LPLD 
Lipoprotein lipase deficiency 
LPLV 
Last Participant’s Last Visit 
LSEC 
Liver sinusoidal endothelial cells 
LTFU 
Long-term follow-up 
MERS-CoV 
Middle East respiratory syndrome-related coronavirus 
MHC 
Major histocompatibility complex  
MMF 
Mycophenolate mofetil 
mRNA 
Messenger ribonucleic acid 
nAb 
Neutralizing antibody 
NAT 
Nucleic acid test 
NAAT 
Nucleic acid amplification testing 
NCT 
National Clinical Trial 
NHF-MASAC 
National Hemophilia Foundation’s Medical and Scientific Advisory Council 
NHP 
Non-human primate  
PBMC 
 
Peripheral blood mononuclear cells  
PCR 
Polymerase chain reaction 
pd 
Plasma derived 
PHI 
Protected health information 
PI 
Principal Investigator 
PK 
Pharmacokinetics 
QoL 
Quality of life 
rAAV 
Recombinant adeno-associated viral vectors  
RBC 
Red blood cells 
rFVIII 
Recombinant factor VIII 
RNA 
Ribonucleic acid 
RPE65 
Retinal pigment epithelium 65 gene 
SAE 
Serious adverse event  
SAP 
Statistical Analysis Plan 
SARS-CoV 
Severe acute respiratory syndrome coronavirus  
SD 
Standard deviation 
SPK-8011  
Study drug in this protocol 
Adeno-associated viral Spark200 vector with B-domain-delated human 
factor VIII gene (aka. AAV-Spark200-BDD-hFVIII) 
SPK-9001  
Adeno-associated viral vector comprised of the AAV-Spark100 capsid, and 

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a codon-optimized FIX mini-gene encoding human FIX-Padua  
(aka. AAV-Spark100-hFIX39- Padua) 
TCZ 
Tocilizumab 
TEAE 
Treatment emergent adverse events 
TEE 
Thrombotic and/or embolic events 
TTR 
Transthyretin 
TPMT 
Thiopurine Methyltransferase 
TTRm 
Modified transthyretin 
ULN 
Upper limit of normal  
vg 
Vector genome  
VLDL 
Very low-density lipoprotein 
VWF 
von Willebrand factor 
WBC 
White blood cell 
WFH 
World Federation of Hemophilia 
WHO 
World Health Organization 
 
 

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13.7 
Protocol Amendment History 
The Protocol Amendment Summary of Changes Table for all amendments are located below. 
DOCUMENT HISTORY 
Document 
Date 
Amendment 7 
09-Feb-2021 
Amendment 6 
29-Sep-2020 
Amendment 5 
27-Jan-2020 
Amendment 4 
08-Nov-2018 
Amendment 3 
09-Aug-2018 
Amendment 2 
24-Aug-2017 
Amendment 1 
21-Nov-2016 
Original Protocol 
17-Oct-2016 
 
SUMMARY OF CHANGES FROM PREVIOUS VERSION: 
 
SECTION OF 
AMENDMENT 7: 
SUMMARY OF REVISIONS MADE: 
RATIONALE: 
Throughout the 
document  
Use new protocol template 
To align with updated 
template per Spark SOP 
1.1 Protocol Synopsis 
Protocol Synopsis has been updated. 
Updates reflect changes made 
throughout Amendment 7. 
1.2 Schema  
Updated Figure 1 (Study Schematic) to 
revise the immunomodulatory regimens for 
Cohorts 1 and 2. 
The study schematic was 
updated to replace reactive 
corticosteroid regimen with 
prophylactic MMF  
1.3 Schedule of 
Events 
Updated Schedule of Events  
• 
Added  
o Review of 
Inclusion/Exclusion criteria 
prior to vector dosing 
o Laboratory collections at 
screening and 3 to 7 days 
prior to vector infusion 
o 
Prophylactic MMF dosing and 
remove reactive corticosteroid 
regimen  
o 
 infusion of MMF for 
Cohort 1.  
o Screening and follow-up 
testing for 
immunomodulation 
o Revised 
assessments/procedures for 
Day 0 pre-SPK-8011 dosing 
Additional screening and 
follow up is required as well 
as weekly follow up while on 
immunomodulation.  
 
CCI

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o Immune profiling to Pre-
SPK-8011 Dosing and 
Weeks 1B, 2-6, 8-11, and 16 
o Immunology to Day 1  
o PAX Gene (RNA) to Pre-
SPK-8011 Dosing and 
Weeks 2 to 6 
• 
Removed 
o ABO group from screening 
o Hematology, chemistry, 
LFT, CRP, immunology, 
and AAV neutralizing 
antibody from Pre-SPK-
8011 Dosing 
2.2.3 
Text related to the immunomodulatory 
regimens was added. 
To provide rationale for the 
administration of MMF and 
the use of 
 IV steroids. 
2.2.5 
Added new section (Summary of Non-
clinical and Clinical Experience with 
Mycophenolate Mofetil) 
The preclinical and clinical 
study results provide evidence 
to support the design of 
Cohort 1. 
2.3.1.2 
Added inhibitor data from ongoing Study 
SPK-8016-101 
To updated inhibitor 
information based on the 
available data 
2.3.1.3 
Removed the appearance of ELISpot signal 
in peripheral blood as a possible or probable 
indicator of a cellular immune response for 
participants with transaminase elevations. 
Note, text referring to use of this as an 
indicator of immune response has been 
removed throughout protocol. 
To provide guidance to the 
investigators based on current 
data 
2.3.1.6 
Adverse events occurring in this study and 
Study SPK-8016-101 were updated. 
To update adverse event 
information based on the 
available data. 
2.3.1.7 
Updated to include MMF and to change the 
timing for review and completion of 
vaccinations prior to the planned day of 
SPK-8011 administration, with provisions in 
timing for participants receiving 
immunosuppressive medication. 
To provide current 
information based on 
available data. 
2.3.1.7.2 
Updated information related to the 
immunomodulatory regimen and FVIII level 
for 2 participants administered tacrolimus in 
this study. 
To provide current 
information based on 
available data. 
2.3.1.7.4 
Added new section (Mycophenolate Mofetil) 
detailing risks associated with this agent. 
To provide the risks 
associated with the addition 
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of the immunomodulating 
agent MMF 
2.3.1.7.5 
Added MMF and clarified references 
To include the 
immunomodulation agent 
MMF 
4.1.1 
Updated to detail immunomodulatory 
regimens for Cohorts 1 and 2 and add time 
frame for administration of TCZ for the first 
2 participants treated with this agent. 
To provide additional 
guidance based on the 
addition of the MMF cohort 
4.1.3 
Updated the details regarding corticosteroid 
use  
To include clinical data based 
on corticosteroid use as well 
as provide rationale for 
removing IV corticosteroids 
as a cohort 
4.1.3.2 
Added MMF to section on other 
immunomodulatory considerations 
To include the 
immunomodulation agent 
MMF 
4.1.3.3 
Added details regarding the prophylactic use 
of TCZ and MMF 
To provide details regarding 
the administration of MMF 
for participants in Cohort 1 
4.1.5 
Updated to include MMF 
immunomodulatory regimen 
To provide additional 
guidance based on the 
addition of the MMF cohort 
4.1.6 
Added Day -2 
To provide guidance based on 
the addition of the MMF 
cohort 
4.1.7 
Revised/clarified timepoints for sample 
collection for immune profiling, PAX gene  
and FVIII activity 
To align with Schedule of 
Events 
4.1.8 
Updated to include MMF 
immunomodulatory regimen 
To include the 
immunomodulation agent 
MMF 
4.2.2 
Increased number of study centers included 
in this study 
To increase projected number 
of study centers 
6.3 
Revised Table 1 to: 
• 
add PK assessments 
• 
add hemophilic arthropathy assessment 
• 
add ECG 
• 
add ANC at screening 
• 
add liver fibrosis diagnostic tests 
• 
add spare plasma collection 
• 
clarify HIV assessments 
To align with Schedule of 
Events 
6.4.1 
Revised screening assessments/procedures to 
align with Schedule of Events 
To align with Schedule of 
Events 
6.5 
Added instructions for 3 to 7 days prior to 
Day 0 
To provide additional 
instructions for MMF cohort 

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6.6 
Added Day -2 
To provide guidance based on 
the addition of the MMF 
cohort 
6.7 
Revised Day 0 and Day 1 
assessments/procedures to align with 
Schedule of Events 
To align with Schedule of 
Events 
6.8 
Revised follow-up observation period 
(Weeks 1-52) assessments/procedures to 
align with Schedule of Events 
To align with Schedule of 
Events 
7.3 
Added/clarified 
 
instructions on administration of 
 
, FVIII protein and SPK-8011. 
To add/clarify dosing 
administration details 
7.4 
Added/clarified instructions for treatment 
compliance with MMF and TCZ 
To include the 
immunomodulation agent 
MMF 
7.9.1 and 7.9.3 
Added statement regarding permitted and 
prohibited therapies 
To clarify the types of 
medications that are 
permitted/prohibited 
10 
Reformatted, restructured, and updated 
statistical considerations  
To align with new template 
format and changes to the 
protocol 
11.1.9 
Revised study/site closure instructions 
To clarify reasons for 
study/site closure 
13.2 
Updated Hemophilia Activities List 
questionnaire to a more current version 
To provide current version of 
questionnaire 
 
 
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SECTION OF 
AMENDMENT 6: 
SUMMARY OF REVISIONS MADE: 
RATIONALE: 
1.1 Protocol Synopsis 
Protocol Synopsis has been updated. 
Updates reflect changes made 
throughout Amendment 6. 
1.2 Schema Figure 1 
Updated study schematic figure 1. 
The study schematic was 
updated to include the cohorts 
in the 1.5x1012 dose. 
1.3 SOE 
Updated Schedule of Events  
 
Additional screening and 
follow up is required for 
participants in cohort 2 of the 
1.5x1012 dose. This includes 
screening labs, three to seven 
days prior to vector, and 
weekly follow up while on 
immunomodulation. In 
addition, the FVIII levels on 
Day 0 were eliminated for all 
participants.  
 
2.2.4 & 2.2.5 
Added Summary of Non-clinical Experience 
with Tocilizumab 
The preclinical study results 
provide evidence to support 
the design of cohort 2 in the 
1.5x1012 dose group. 
2.3.1 
Added risks associated with tocilizumab 
 
The risks associated with 
TCZ were provided to 
support the design of cohort 2 
in the 1.5x1012 dose group. 
2.4 
Updated Study Rationale with most recent 
published data. 
Results from gene therapy in 
hemophilia have been 
published since the previous 
amendment. Data from the 
Spark participants to date 
provides the rationale for this 
amendment. 
4.1.1 
Added cohorts 1 and 2 to the study design 
and provided instruction on sequence of 
enrollment. 
 
Details for the expansion and 
enrollment sequence of the 
1.5x1012 dose into two 
cohorts are included. A 
description of the expansion 
of cohorts up to 10 
participants is described if 
additional data is needed. 
4.1.1 
Refined dose cohort expansion. 
Details for the expansion  and 
enrollment sequence of the 
1.5x1012 dose into two 
cohorts are included. A 
description of the expansion 
of cohorts up to 10 

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participants is described if 
additional data is needed.  
4.1.3.1 
Added SARS-coV2 testing  
Multiple effects of COVID-
19 on the hemostatic system 
have been described, 
including the development of 
anti-phospholipid antibodies 
(Lupus-like anticoagulants), 
which might confound 
interpretation of one-stage 
clotting factor VIII assays 
4.2.2 
Updated study design to include up to 50 
participants. 
The expansion of the 1.5x1012 
dose into three cohorts will 
require an increase in the 
number of participants in the 
trial. 
5.2 
Provided clarification in eligibility for 
assessing liver fibrosis. 
On occasion, discordant 
results as it relates to liver 
health have been found in 
review of the medical record. 
The Fibro scan is considered 
the gold standard in 
determining liver 
elasticity/fibrosis. This 
protocol was clarified to 
elevate this test as the 
determinant for eligibility. 
5.2 
Exclusion criteria updated to included 
gastrointestinal disease, cancer, and latent 
infectious disease due to the addition of 
immunomodulation in the amendment. 
The use of 
immunomodulation agents 
has been included in the study 
design. The exclusion criteria 
changes are reflective of 
contraindications identified in 
the package insert for TCZ. 
2.2.4 & 2.2.5 
Added preclinical experience with 
tocilizumab 
The preclinical study results 
provide evidence to support 
the design of cohort 2 in the 
1.5x1012 dose group. 
2.3.1 
Added risks associated with tocilizumab  
 
The risks associated with 
TCZ were provided to 
support the design of cohort 2 
in the 1.5x1012 dose group. 
6.2.6 
Added ability to perform genetic analyses on 
archived samples   
Archived samples may be 
used for genetic sequencing if 
the participant provides 
consent. 
6.4.1 
Changed the FVIII PK analysis from Day 0 
to historic or during the screening period.  
The PK analysis added to the 
complexity of Day 0. Historic 

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PK results provide sufficient 
information should it be 
needed to compare FVIII 
response post gene therapy.  
6.7.1 
Changed the Day 0 FVIII infusion to a 
routine prophylactic treatment. 
 
The PK analysis is no longer 
needed on Day 0. Patients 
with hemophilia administer 
prophylactic treatments 
routinely. This will provide 
bleed protection for a portion 
of week one.  
6.5 & 6.6 
Added additional laboratory assessments for 
Cohort 2 prior to dosing day and following 
vector infusion.  
 
Additional laboratory 
assessments are required for 
participants in cohort 2 of the 
1.5x1012 dose due to the 
planned use of TCZ. The 
testing
 
is required 
to confirm that the critical 
laboratory values have not 
changed during the screening 
period.  Weekly follow up 
while on immunomodulation 
is recommended in the 
clinical management of 
participants receiving 
immunomodulation. NAAT 
testing for infection with 
SARS-coV2 in asymptomatic 
study participants prior to 
immune suppression and to 
recommend NAAT testing in 
symptomatic study 
participants prior to immune 
suppression has been included 
for participant safety.  
9.1.1 
Updated AE language 
 
AE language was updated to 
include standard toxicology 
reporting. Clarification of the 
timeframe to collect AEs was 
provided. 
 
 
 
Throughout 
Updated text and references as it relates to 
the Immunomodulatory clinical experience 
and the cohort design in this trial. 
Literature in the gene therapy 
is regularly published. Data 
and references were updated 
in all areas of the protocol to 
maintain relevant resources.  
Data from the Spark 
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participants to date provides 
the rationale for this 
amendment. 
 
Document 
Description of Main Changes 
Amendment 
5 (version 
6.0) 
1. Updated study schematic figure 1. 
2. Removed language requiring prophylactic steroid administration on Week 
4. 
3. Updated corticosteroid regimen language to include use of 
 
corticosteroids in response to an immune response trigger. 
4. Updated language to allow the investigator in collaboration with the 
Sponsor to use other immunomodulatory agents, should they be required, 
to reduce long term and high dose steroid exposure 
5. Inserted Thiopurine methyltransferase (TPMT) as a screening requirement. 
6. Added risks associated with azathioprine and tacrolimus in section 1.2.3 
7. Updated text and references as it relates to immunomodulatory clinical 
experience in Hemophilia Gene Therapy trials. 
Amendment 
4 (Version 
5.0) 
1. Introduced the use of SPK-8011 drug substance produced using a new 
manufacturing process (see Section 9.1 for additional information).  
2. Revised Inclusion criterion #6 to provide further clarity guidance for 
investigators.   
3. Revised Figure 1 to clarify the dose cohort graphic. 
4. Removed instruction on signs and symptoms of thrombotic and/or embolic 
events from the Schedule of Events.  
5. Added emicizumab as a prohibited therapy 
6. Updated corticosteroid regimen language to allow investigator’s discretion 
in determining if prophylactic corticosteroids should be administered to 
participants 
7. Clarified washout language to include washout period for participants 
taking non-factor replacement products. 
8. Inserted the Change in Level of Activities Questionnaire to Appendix 2. 
9. Clarified other potentially confusing text and incorporated administrative 
changes throughout the protocol. 
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Document 
Description of Main Changes 
Amendment 
3 (Version 
4.0) 
1.  Introduced a prophylactic corticosteroid regimen (see Section 3.2.4). 
2.  Deleted bullet regarding steroid use in Section 7.1.2 (Permitted Therapies) 
as corticosteroids are now required, not permitted. 
3. Moved paragraph from Section 3.2.5 regarding long term use of 
corticosteroids to Section 1.2.3 under Possible Side Effects from 
Corticosteroids. 
4. Updated Schedule of Events to include prophylactic steroid regimen. 
5. Added Appendix 5 Toxicity Scale 
6.  Updated the screening period from 12 weeks to 16 weeks  
Protocol 
Amendment 
2 (Version 
3.0) 
1. Clarification to Exclusion Criteria 1 and 3 (Hepatitis B and C language), 2 
and 7. 
2. Dose escalation criteria revised; added potential to include an intermediate 
dose. 
3. Extended the screening period up to 12 weeks. 
4. Streamlining study procedures to reduce participant burden. Revisions to 
study procedures, include: 
a. Removed spare plasma collections at Day 0, Weeks 1-11, 14-22, 30, 
34, 46 
b. Removed physical exam and weight collections at Weeks 16, 22, 30 
and 46. 
c. Removed immunology collections at Screening, Day 0 post-FVIII and 
Day 0 post-vector and Day 1. 
d. Removed FVIII inhibitor collections at Weeks 7, 12, 14, 26 and 40 
e. Removed FVIII dose at Week 52/EOS  
f. Clarified central lab vs. local lab collections 
5. Added repeat of Week 46 procedures, except for ELISpot, in the event that 
a LTFU study is not enrolling at the time of the subject’s Week 52/EOS 
visit. 
6. Changed ‘Hepatic transaminase elevation requiring immunosuppression’ 
to a primary endpoint from a secondary endpoint. 
7. Updated Section 5 to include all assessments for all study visits. 
8. Clarified the Safety Reporting section including revisions to causality and 
severity assessments (Section 12.2), addition of new sections (i.e., Section 
12.1.3 Adverse Events of Special Interest, Section 12.3 Time Period and 
Frequency for Collecting AE and/or SAE Information). 
9. Removed the Independent Immunosuppressive Therapy Dosing 
Committee as none will be used in this study, 
10. Clarified Section 13 Administrative Procedures and Section 13 Further 
Requirements and General Information, including addition of new sections 

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Document 
Description of Main Changes 
(i.e., Section 13.3 Source Documents, Section 13.6 Study and Site 
Closure).  
11. Additional wording updated throughout the protocol to provided clarity.  
Protocol 
Amendment 
1 (Version 
2.0) 
1. Increased number of participants from 18 to 30. 
2. Revised Inclusion Criteria 3, 4 and 7, and removed Inclusion Criterion #5. 
3. Revised Exclusion Criterion 8. 
4. Added requirement that 6-week interval required at each dose level for the 
first two participants at each dose level. 
5. Clarified the Dose Expansion and Escalation criteria. 
6. Specified the time points collected for immune profiling. 
7. Revised the guidelines to initiate corticosteroid therapy. 
8. Modified the study stopping rules for hepatic involvement. 
Original 
Protocol 
(Version 1.0) 
Not Applicable