Conditions: Severe Hemophilia B
Allocation: NON_RANDOMIZED | Intervention model: SINGLE_GROUP
Enrollment: 123
Healthy volunteers: no

Brief summary:
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.

Detailed description:

Arms:
arm 1: 50 IU/kg rFIXFc via intravenous (IV) injection once every 7 days initially, then at a dose indicated by the participant's baseline pharmacokinetic (PK) assessment that ensured a target trough of 1% to 3% above baseline or higher, as clinically indicated. Adjustments to the initial weekly dose of rFIXFc (50 IU/kg) were to be made based on baseline PK assessments, occurrence of spontaneous bleeding episodes, and the trough levels, which were to be monitored at Weeks 4, 16, 26, and 39.

Prior to the first dose of rFIXFc, participants in the Sequential PK subgroup were to receive a single dose of 50 IU/kg BeneFIX administered IV in the clinic, followed by PK sampling. A single dose of 50 IU/kg rFIXFc was administered following a 120-hour washout from BeneFIX, followed by PK sampling for a baseline PK profiling. At Week 26 (±1 week) subjects were to receive a single dose of 50 IU/kg rFIXFc for repeat PK profiling. arm 2: 100 IU/kg rFIXFc via IV injection once every 10 days initially, then at an interval derived from the baseline PK assessment that ensured a target trough of 1% to 3% above baseline or higher, as clinically indicated. Adjustments to the initial 10-day interval were to be made based on baseline PK assessments and trough levels, which were monitored at Weeks 4, 16, 26, and 39. arm 3: 20 to 100 IU/kg rFIXFc via IV injection, or the dose indicated by the participant's baseline PK to target a plasma level of 20% to 100%, as needed for the treatment of mild to severe bleeding episodes arm 4: The surgical period and dosing are dependent on the type of surgery the participant undergoes. Participants who started the study in one of the other treatment arms prior to surgery will return to the original treatment arm. Participants who joined the study in the Surgery arm will be assigned to one of the other treatment arms following post-operative rehabilitation.

Interventions: intervention 1: Factor IX (rFIXFc) intervention 2: rFIX
Intervention descriptions: intervention 1: None intervention 2: None

Protocol document: