FDA Approves First Gene Therapy to Treat Severe Hemophilia A

Today the FDA approved Roctavian (valoctocogene roxaparvovec), the first gene therapy for adults with severe hemophilia A. This is the second gene therapy approval for a form of hemophilia—a common blood clotting disorder.

Roctavian is an investigational, one-time AAV-based gene therapy developed by BioMarin that delivers a working copy of the faulty gene into liver cells with instructions to produce the missing clotting factor. Data from the GENEr8-1 study, a global phase III study including 134 participants, shows the average annualized bleed rate decreased by 80% from the baseline and factor VIII usage decreased by 94% in year three compared to the baseline. Additionally, at the end of year three, 92% of patients remained off prophylaxis. 

Hemophilia is an X-linked genetic disease that prevents blood from clotting properly due to missing or defective proteins called clotting factors. In Hemophilia A, patients have a deficiency of clotting factor VIII, which can lead to prolonged internal and external bleeds. When it’s serious, patients can experience painful, spontaneous bleeds into their muscles or joints that can damage organs, including the brain. Approximately one in 10,000 people have hemophilia A.

Results from the GENEr8-1 study were published in the New England Journal of Medicine in 2022. BioMarin reports this study is the longest and largest to date for a hemophilia gene therapy. 

I’m greatly encouraged by the trial results and the therapy’s approval. The patients who live with hemophilia A—and the families that care for them—deserve a treatment that will help them be free of the pain and the danger that comes with the disease. 

Jeffrey Chamberlain, PhD is president of ASGCT and a professor and McCaw Chair in Muscular Dystrophy at the University of Washington.

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