Phase 3 Study Update of Recombinant Factor IX FC Fusion Protein for Hemophilia B

Biogen Idec and Swedish Orphan Biovitrum (Sobi) announced positive results from B-LONG, a global, open-label, multi-center Phase 3 clinical study that evaluated the efficacy, safety and pharmacokinetics of a new long-lasting intravenously-injected clotting factor candidate, recombinant Factor IX Fc fusion protein (rFIXFc), in people with hemophilia B.

In the B-LONG study, 123 male patients aged ≥12 years were enrolled. The B-LONG study had four treatment arms: weekly prophylaxis, individualized interval prophylaxis, episodic treatment and perioperative management (Arms 1, 2, 3 and 4, respectively).

The overall median annualized bleeding rates (including spontaneous and traumatic bleeds) were 2.95 in the weekly prophylaxis arm, 1.38 in the individualized interval prophylaxis arm, and 17.69 in the episodic treatment arm. In the individualized interval prophylaxis arm, the median dosing interval during the last 6 months on study was 14 days.

Control of bleeding was assessed in all patients who experienced a bleeding episode during the study. Overall, 90.4% of bleeding episodes were controlled by a single injection of rFIXFc.

Recombinant FIXFc was assessed in the perioperative management of 12 patients undergoing 14 major surgical procedures. The treating physicians rated the hemostatic efficacy of rFIXFc as excellent or good in 100% of these surgeries.

B-LONG included a pharmacokinetic (PK) analysis of rFIXFc in all patients in the study. In a protocol-defined subset of patients with extensive PK sampling, the approximate terminal half-life of rFIXFc was 82 hours vs. 34 hours for BeneFIX (coagulation factor IX [recombinant]; Pfizer).

Recombinant FIXFc is a clotting factor developed using proprietary monomeric Fc fusion technology, which makes use of a natural pathway to recycle rFIXFc in circulation and enable it to remain in the body longer.

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