for males ages 18-65 (full criteria)
at San Francisco, California and other locations
study started
completion around



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).

Official Title

Phase 3, Open-label, Single-arm Study to Evaluate Efficacy and Safety of FIX Gene Transfer With PF-06838435 (rAAV-Spark100-hFIX-R338L) in Adult Male Participants With Moderately Severe to Severe Hemophilia B (FIX:C =2%) (BeneGene-2)


Hemophilia B, PF 06838435, Hemophilia, Factor IX, FIX, Gene Therapy, Infusion, rAAV Spark100 hFIX Padua, rAAV Spark100-hFIX-R338L, R338L, BeneGene 2, Hematological Diseases, Annualized bleeding rate (ABR), Hemophilia A, PF-06838435/ fidanacogene elaparvovec


You can join if…

Open to males ages 18-65

  • 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

You CAN'T join if...

  • 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


  • UCSF - Clinical Research Center
    San Francisco California 94143 United States
  • UCSF - Outpatient Hematology Clinic
    San Francisco California 94143 United States


in progress, not accepting new patients
Start Date
Completion Date
To obtain contact information for a study center near you, click here.
Phase 3 Hemophilia Research Study
Study Type
About 51 people participating
Last Updated