The U.S. Food and Drug Administration (FDA) has approved a new gene-therapy treatment for Hemophilia B. The FDA announcement says that Hemgenix (entranacogene dezaparvovec) is designed to reduce reliance on current treatment methods for individuals with severe Hemophilia B symptoms.

Hemophilia is a medical condition defined by a lack of clotting ability, leading to prolonged, severe bleeding episodes. Hemophilia B is caused by a genetic disorder that results from insufficient levels of the protein “Factor IX” which causes clotting to stop bleeding. Patients with Hemophilia B experience prolonged or heavy bleeding after a dental procedure, injury or surgery. These prolonged bleeding episodes can sometimes occur spontaneously and lead to blood in the joints, muscles or internal organs such as the lungs or brain.

Hemophilia B is treated with routine intravenous infusions of Factor IX replacement products. While IV infusions produce sufficient levels of clotting factor, they are not a permanent solution. According to the FDA, Hemgenix functions as a virus vector-based gene therapy that treats patients with severe Hemophilia B. Unlike regular Factor IX infusions, Hemgenix is a one-time infusion that carries a functional Factor IX gene. This gene is brought to the liver where it is expressed and begins increasing Factor IX levels in the blood.

In two studies designed to evaluate the safety and effectiveness of Hemgenix, patients were measured based on how much their annualized bleeding rate decreased by. The result was a reduction in the need for Factor IX replacement treatments and a 54% reduction in annualized bleeding rate compared to the placebo group. The clinical study also noted that patients receiving treatment with Hemgenix experienced side effects including:

  • Liver enzyme elevations
  • Headache
  • Mild infusion-related reactions
  • Flu-like symptoms 

The FDA recommended that patients who receive Hemgenix be monitored for adverse reactions or elevated liver enzyme levels.

Dr. Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research, stated, “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.” 

Dr. Marks also noted that treatments such as gene therapy have been on the horizon for over 20 years and treatments like Hemgenix stand to potentially improve patients’ quality of life.