CSL Behring announced it has submitted a biologics license application (BLA) to the United States Food and Drug Administration (FDA) for the marketing authorisation of its long-acting fusion protein linking recombinant coagulation factor IX with recombinant albumin (rIX-FP). Once approved by the FDA, rIX-FP (Coagulation Factor IX {Recombinant}, Albumin Fusion Protein) will provide people with hemophilia B and their physicians a long-acting treatment option with dosing intervals up to 14 days.

“As we mentioned at our recent R&D investor briefing, submission of our BLA to the FDA for rIX-FP is a significant milestone for CSL Behring’s recombinant factor IX development program and moves us one step closer to bringing this innovative therapy to haemophilia B patients in the US,” said Dr. Andrew Cuthbertson, chief scientific officer and R&D Director, CSL Limited. “Our strong partnership with and commitment from the hemophilia community led us to develop rIX-FP based on novel recombinant albumin fusion technology. This technology has led to a long-acting treatment candidate that continues our legacy of improving the well-being of patients with bleeding disorders and other rare diseases.”

CSL Behring’s BLA is based on the results from the PROLONG-9FP phase II/III (patients ages 12 to 61 years) study. 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 severe hemophilia B (FIX = 2 per cent ).

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.

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 programmea provides orphan status to unique 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 US Orphan designation qualifies the sponsor of the product for important tax credits, elimination of FDA license application fees and certain marketing incentives.

Haemophilia 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 characterised by prolonged or spontaneous bleeding, especially into the muscles, joints, or internal organs. Nearly all hemophilia B patients are male.

CSL Behring is a leader in the plasma protein therapeutics industry. Committed to saving lives and improving the quality of life for people with rare and serious diseases, the company manufactures and markets a range of plasma-derived and recombinant therapies worldwide.

CSL Behring therapies are used around the world to treat coagulation disorders including hemophilia and von Willebrand disease, primary immune deficiencies, hereditary angioedema and inherited respiratory disease, and neurological disorders in certain markets. The company’s products are also used in cardiac surgery, organ transplantation, burn treatment and to prevent hemolytic disease of the newborn.