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

Running, not enrolling · Phase 3

Conditions studied: Hemophilia B

In brief

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).

Key facts

Study ID: NCT03861273
Run by: Pfizer
People needed: 51
Starts: 2019-07-29
Expected to finish: 2031-02-25
Last updated by the study team: 2026-06-01

Who can join

Age: 18 and older, up to 65. Sex: male. Healthy volunteers: not accepted.

You may qualify if…

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 may not qualify 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

Where it is running

University of California, San Francisco - Clinical Research Center — San Francisco, California, United States
University of California, San Francisco - Outpatient Hematology Clinic — San Francisco, California, United States
The Regents of the University of California, San Francisco campus — San Francisco, California, United States
Hemophilia and Thrombosis Center at the University of Colorado Anschutz Medical Campus — Aurora, Colorado, United States
Regents of the University of Colorado University of Colorado Denver, Office of Grants and Contracts — Aurora, Colorado, United States
Indiana Hemophilia & Thrombosis Center, Inc. — Indianapolis, Indiana, United States
Indiana Hemophilia and Thrombosis Center, Inc — Indianapolis, Indiana, United States
Innovative Hematology, Inc. — Indianapolis, Indiana, United States
St. Vincent Hospital & Health Care Center, Inc. — Indianapolis, Indiana, United States
Madison Radiological Group — Madison, Mississippi, United States
Mississippi Center for Advanced Medicine — Madison, Mississippi, United States
The Trustees of the University of Pennsylvania, Office of Clinical Research- Legal — Hamilton, Pennsylvania, United States
Center for Human Phenomic Science — Philadelphia, Pennsylvania, United States
Investigational Drug Service — Philadelphia, Pennsylvania, United States
Penn Blood Disorder Center — Philadelphia, Pennsylvania, United States
The Trustees of the University of Pennsylvania, Office of Clinical Research- Legal — Philadelphia, Pennsylvania, United States
Royal Prince Alfred Hospital — Camperdown, New South Wales, Australia
Royal Adelaide Hospital — Adelaide, South Australia, Australia
The Alfred Hospital — Melbourne, Victoria, Australia
Fiona Stanley Hospital — Murdoch, Western Australia, Australia
Royal Brisbane and Women's Hospital — Herston, Australia
Centro Estadual de Hemoterapia e Hematologia Marcos Daniel Santos - Hemoes — Vitória, Espírito Santo, Brazil
Centro de Hematologia e Hemoterapia - Hemocentro de Campinas - UNICAMP — Campinas, São Paulo, Brazil
Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo — São Paulo, São Paulo, Brazil
UCSF IDS Pharmacy — San Francisco, California, United States

Full record on ClinicalTrials.gov

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