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
Summary
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).
Timeline
- Start
- 2019-07-29
- Primary completion
- 2022-11-16
- Completion
- 2031-02-25
Outcome
Met primary endpoint
registry analysis (non-inferiority test); FIX Prophylaxis vs PF-06838435; p = 0.0081; Mean Difference (Final Values) -3.13 (95% CI -5.44 to -0.81) NCT03861273 ↗
paper This result shows the noninferiority and superiority of fidanacogene elaparvovec to prophylaxis. PMID 39321362 ↗
release “The BENEGENE-2 study met its primary endpoint of non-inferiority and superiority in the annualized bleeding rate (ABR)” pfizer.com ↗
release “BENEGENE-2 met its primary endpoint of non-inferiority in the ABR of total bleeds post-BEQVEZ infusion” pfizer.com ↗
Publications
- Wojciechowski J, Gaitonde P, Hughes JH, Ravva P. Population Modeling of Factor IX Activity Following Administration of Fidanacogene Elaparvovec Gene Therapy in Participants with Hemophilia B. Clin Pharmacokinet. 2025 Oct;64(10):1531-1548. doi: 10.1007/s40262-025-01535-y. Epub 2025 Aug 1.
- Cuker A, Kavakli K, Frenzel L, Wang JD, Astermark J, Cerqueira MH, Iorio A, Katsarou-Fasouli O, Klamroth R, Shapiro AD, Hermans C, Ishiguro A, Leavitt AD, Oldenburg JB, Ozelo MC, Teitel J, Biondo F, Fang A, Fuiman J, McKay J, Sun P, Rasko JEJ, Rupon J; BENEGENE-2 Trial Investigators. Gene Therapy with Fidanacogene Elaparvovec in Adults with Hemophilia B. N Engl J Med. 2024 Sep 26;391(12):1108-1118. doi: 10.1056/NEJMoa2302982.
Drugs
| Evaluation | Drug | Modality | Dose | Route |
|---|---|---|---|---|
| Subject | fidanacogene elaparvovec | Gene therapy (AAV / viral vector) | 5e+11 vg/kg | Intravenous |