CSL Behring announced that the U.S. Food and Drug Administration (FDA) has accepted for review its Biologics License Application (BLA) for the marketing authorization of its long-acting fusion protein linking recombinant coagulation factor IX with recombinant albumin (rIX-FP). Upon FDA approval, rIX-FP will provide hemophilia B patients with a long-acting treatment option with dosing intervals up to 14 days.
“FDA’s decision to accept for review the rIX-FP BLA brings CSL Behring one step closer to providing this innovative therapy to hemophilia B patients in the U.S.,” said Dr. Andrew Cuthbertson, Chief Scientific Officer and R&D Director, CSL Limited. “The development of rIX-FP underscores CSL Behring’s protein science capabilities, thorough understanding of the hemophilia community, and commitment to improving the well-being of patients with hemophilia B.”
About PROLONG-9FP Clinical Development Program
CSL Behring’s BLA is based on the results from the Phase II/III study (patients ages 12 to 61 years) in the PROLONG-9FP program. The Phase II/III pivotal study was an open-label, multicenter, safety, pharmacokinetic (PK) and efficacy study of rIX-FP in previously treated patients with hemophilia B (FIX ≤ 2%).
This study was designed to compare the change in frequency of spontaneous bleeding events between on-demand treatment and a weekly prophylaxis regimen in patients previously receiving only on-demand treatment; and the number of patients developing inhibitors against factor IX as primary outcome measures. The study evaluated multiple prophylaxis regimens, including 7-day and 14-day intervals. A sub-study evaluated the prevention and control of bleeding in patients with hemophilia B undergoing a surgical procedure.
Study design details for rIX-FP (CSL654) are available at clinicaltrials.gov.
CSL Behring engineered rIX-FP to extend the half-life of recombinant factor IX through genetic fusion with recombinant albumin. CSL Behring selected recombinant albumin as its recombinant genetic fusion partner for its coagulation factor proteins due to its long physiological half-life. In addition, recombinant albumin has been shown to have a good tolerability profile, low potential for immunogenic reactions and a well-known mechanism of clearance. The cleavable linker connecting recombinant factor IX and recombinant albumin has been specifically designed to preserve the native function of the coagulation factor in the fusion protein, while benefiting from recombinant albumin’s long physiological half-life.
In 2012, the FDA granted Orphan Drug Designation for rIX-FP for the treatment and prophylaxis of bleeding episodes in patients with hemophilia B. The designation includes routine prophylaxis treatment, control and prevention of bleeding episodes, and prevention and control of bleeding in perioperative settings. The FDA’s Orphan Drug Designation program provides orphan status to drugs and biologics defined as those intended for the safe and effective treatment or prevention of rare diseases that affect fewer than 200,000 people in the U.S. Orphan designation qualifies the sponsor of the product for important tax credits, elimination of FDA license application fees and certain marketing incentives.
About Hemophilia B
Hemophilia B (congenital factor IX deficiency) is characterized by deficient or defective factor IX and affects approximately 1 in 25,000 to 50,000 people. Hemophilia B is a congenital bleeding disorder characterized by prolonged or spontaneous bleeding, especially into the muscles, joints, or internal organs. Nearly all hemophilia B patients are male.