FDA Approves $3.5 Million per Dose Hemophilia B Gene Therapy

Last week, the FDA’s Center for Biologics Evaluation and Research announced the approval of Hemgenix, an adeno-associated virus vector-based gene therapy for adults with hemophilia B (congenital Factor IX deficiency). In a recent clinical trial, the drug created by CSL Behring was shown to reduce the rate of annual bleeds and the need for prophylactic therapy for patients with hemophilia B.   

Hemgenix was tested in the ongoing Phase III HOPE-B clinical trial that enrolled 54 adult hemophilia B patients. Seven months post-infusion, these patients' adjusted annualized bleeding rate was reduced by 54%. Additionally, 94% of patients were able to discontinue their use of prophylactic treatments after infusion.

The most common side effects associated with Hemgenix treatment were liver enzyme elevations, headache, elevated blood enzyme levels, and other flu-like symptoms.

“Over the years, we have seen a variety of advancements for the hemophilia community, but gene therapy is the first treatment option to offer those living with hemophilia B — and caregivers — the possibility of freedom from the need for regular, ongoing infusions,” shared the Chief Operating Officer of The Coalition for Hemophilia B, Kim Phelan.

Hemophilia patients often endure invasive treatments just to manage their symptoms. Most patients need routine infusions of recombinant clotting factor products that prevent bleeds. Adherence to this intense treatment regimen can be difficult, and patients rely on mHealth devices to keep them on track with their medication adherence goals.

Hemophilia affects 1 in 5,000 people, and around 30,000 people live with the disease in the United States. People with hemophilia bleed without clotting and are more likely to experience internal bleeding episodes that can be dangerous. The advent of one-time therapies like Hemgenix may allow patients to forgo these frequent treatments and regain agency over their daily life.

“Gene therapy for hemophilia has been on the horizon for more than two decades. 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,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research.

In addition to Hemgenix being the first gene therapy to treat Hemophilia B, it will also be the most expensive drug in the world, priced at $3.5 million per dose. The price surpassed Bluebird Bio’s Zynteglo, another rare disease gene therapy, with a $3 million price tag. CSL Behring plans to commercialize its therapy immediately in the United States.