Phase I/II, open-label, multicenter, safety, efficacy and PK study of a recombinant coagulation factor IX albumin fusion protein (rIX-FP) in subjects with hemophilia B.

Recombinant fusion protein linking coagulation factor IX with albumin (rIX-FP) is a novel recombinant albumin fusion protein designed to extend the half-life of recombinant factor IX (rFIX), which is used in the management of hemophilia B. Clinical evaluation of rIX-FP in humans is underway, including a recently completed phase I/II, open-label, multicenter, study that assessed the safety, pharmacokinetics, and efficacy of rIX-FP in patients with severe hemophilia B. A total of 17 patients received rIX-FP (25 IU/kg) as either on-demand therapy (n = 4) for 20 weeks or weekly prophylaxis (n = 13) for up to 44 weeks. Preliminary results confirm that rIX-FP has an excellent safety profile and a pharmacokinetic profile highlighted by a marked extended half-life, suggesting that weekly prophylaxis with rIX-FP at a dose of 25 IU/kg may be appropriate in patients with severe hemophilia B, and that extended dosing intervals (10-14 days) may be feasible in some patients. A phase II/III study evaluating the safety and efficacy of rIX-FP in patients with hemophilia B is underway.