The trial is taking place at:

Indiana Hemophilia and Thrombosis Center | Indianapolis, IN

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A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B (BENEGENE-2)

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Status and phase

Active, not recruiting
Phase 3


Hemophilia B


Biological: PF-06838435/ fidanacogene elaparvovec

Study type


Funder types



2022-502844-11-00 (Other Identifier)
2018-003086-33 (EudraCT Number)

Details and patient eligibility


This study will evaluate the efficacy and safety of PF-06838435 (a gene therapy drug) in adult male participants with moderately severe to severe hemophilia B (participants that have a Factor IX circulating activity of 2% or less). The gene therapy is designed to introduce genetic material into cells to compensate for missing or non-functioning Factor IX. Eligible study participants will have completed a minimum 6 months of routine Factor IX prophylaxis therapy during the lead in study (C0371004). Participants will be dosed once (intravenously) and will be evaluated over the course of 6 years. The main objective of the study will evaluate the annualized bleeding rate [ABR] for participants treated with gene therapy versus standard of care (SOC) therapy (FIX prophylaxis replacement regimen).


51 patients




18 to 65 years old


No Healthy Volunteers

Inclusion and exclusion criteria

Inclusion Criteria

  • Males who completed 6 months of Factor IX prophylaxis therapy during the lead-in study (C0371004) prior to providing consent at the screening visit for this study.
  • Documented moderately severe to severe hemophilia B (Factor IX activity < =2%)
  • Previous experience with FIX therapy (=>50 documented exposure days to a FIX protein product)
  • Suspension of prophylaxis therapy for hemophilia B after administration of the study drug
  • Laboratory values (hemoglobin, platelets and creatinine) within study specified limits
  • Agree to contraception until components of the drug are eliminated from their body
  • Capable of giving signed informed consent

Exclusion Criteria

  • Anti-AAVRh74var neutralizing antibodies (nAb) titer above the established threshold (ie, positive for nAb).
  • History of inhibitor to Factor IX or inhibitor detected during screening. Clinical signs or symptoms of decreased response to Factor IX
  • Hypersensitivity to Factor IX replacement product or IV immunoglobulin administration
  • History of chronic infection or other chronic disease
  • Any conditions associated with increased thromboembolic risk
  • Concurrent clinically significant major disease or condition unsuitable for participation and/or may interfere with the interpretation of study results
  • Laboratory values at screening visit that are abnormal or outside acceptable study limits
  • Current unstable liver or biliary disease
  • Currently on antiviral therapy for hepatitis B or C
  • Planned surgical procedure requiring Factor IX surgical prophylactic factor treatment 15 months from screening visit
  • Use of restricted therapies (e.g., blood products, acetylsalicylic acid [aspirin] or ibuprofen, other investigational therapy, and by-passing agents)
  • Previously dosed in a gene therapy research trial at any time or in an interventional clinical study within 12 weeks of screening visit
  • Active hepatitis B or C; hepatitis B surface antigen, hepatitis B virus deoxyribonucleic acid positivity, or hepatitis C virus ribonucleic acid positivity
  • Significant liver disease
  • Serological evidence of HIV1 or HIV2 infection with either CD4+ cell count <=200 mm3 and/or a viral load >20 copies/mL
  • Study and sponsor staff involved in the conduct of the study and their families
  • Unable to comply with study procedures
  • Sensitivity to heparin or heparin induced thrombocytopenia
  • Sensitivity to any of the study interventions, or components thereof, or drug or other allergy

Trial design

Primary purpose




Interventional model

Single Group Assignment


None (Open label)

51 participants in 1 patient group

PF-06838435/ fidanacogene elaparvovec
Experimental group
Biological: PF-06838435/ fidanacogene elaparvovec

Trial documents

Trial contacts and locations



Central trial contact

Pfizer Call Center

Data sourced from

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