FDA Approves First Gene Therapy to Treat Adults with Hemophilia B

On November 22, the U.S. Food and Drug Administration approved Hemgenix (etranacogene dezaparvovec), an adeno-associated virus (AAV) vector-based gene therapy. It is approved for the treatment of adults with hemophilia B who currently use factor IX (FIX) prophylaxis therapy, or have current or historical life-threatening hemorrhage, or have repeated, serious spontaneous bleeding episodes.

Safety and effectiveness of the therapy were evaluated via two clinical studies of 57 adult men 18 to 75 years of age with severe or moderately severe hemophilia B. According to a new FDA release, decreases in annualized bleeding rate (ABR) were a primary measure of the therapy’s effectiveness. Results of one study showed that the 54 participants had increases in FIX activity levels, a decreased need for routine FIX replacement prophylaxis, and a 54% reduction in ABR compared to baseline.

The most common adverse reactions associated with Hemgenix treatment were liver enzyme elevations, headache, mild infusion-related reactions, and flu-like symptoms.

“Gene therapy for hemophilia has been on the horizon for more than two decades. Despite advancements in the treatment of hemophilia, the prevention and treatment of bleeding episodes can adversely impact individuals’ quality of life,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research. “Today’s approval provides a new treatment option for patients with Hemophilia B and represents important progress in the development of innovative therapies for those experiencing a high burden of disease associated with this form of hemophilia.”

In light of this FDA approval, Dr. Len Valentino, CEO of the National Hemophilia Foundation, said: “It’s an exciting time for the bleeding disorders community as new and ground breaking treatment options become available. It is great to see this innovation for people living with Hemophilia B, and we will continue our work to ensure all people with inherited bleeding and blood disorders have full access to Hemgenix and like products as they come to market. While this development is a significant step forward from bench to bedside for the hemophilia B community, receiving gene therapy is a decision that should be made with thoughtful consideration with one’s family and medical team.”

Read the full FDA release here.

Source: FDA news release,  November 2022, US Policy, Advocacy and Government Affairs Team, CSL Behring Biotherapies for Life™