Study of Recombinant Factor IX Fc Fusion Protein (rFIXFc) in Participants With Hemophilia B

B-LONG: An Open-Label, Multicenter Evaluation of the Safety, Pharmacokinetics, and Efficacy of Recombinant, Long-acting Coagulation Factor IX Fc Fusion Protein (rFIXFc) in the Prevention and Treatment of Bleeding in Previously Treated Subjects With Severe Hemophilia B

The primary objectives of the study were: to evaluate the safety and tolerability of rFIXFc; to evaluate the efficacy of rFIXFc in all treatment arms; to evaluate the effectiveness of prophylaxis over on-demand (episodic) therapy by comparing the annualized number of bleeding episodes between participants receiving rFIXFc on each prevention (prophylaxis) regimen and participants receiving rFIXFc on an episodic regimen. The secondary objectives of the study were: to evaluate and assess the pharmacokinetic (PK) parameter estimates of rFIXFc and rFIX (BeneFIX®) at baseline in the Sequential PK subgroup as well as rFIXFc at Week 26 (±1 week); to evaluate participants' response to treatment; to evaluate rFIXFc consumption.

Inclusion Criteria:

• Male and 12 years of age and older and weigh at least 40 kg
• Diagnosed with hemophilia B (baseline Factor IX level less than or equal to 2%)
• History of at least 100 exposure days to any Factor IX product
• Platelet count ≥100,000 cells/μL

Exclusion Criteria:

• History of Factor IX inhibitors
• Kidney or liver dysfunction
• Diagnosed with another coagulation defect other than hemophilia B
• Prior history of anaphylaxis associated with any Factor IX or intravenous (IV) immunoglobulin administration