For immediate release:

Today, the U.S. Food and Drug Administration approved Hemgenix (etranacogene dezaparvovec), an adeno-associated virus vector-based gene therapy for the treatment of adults with hemophilia B (congenital factor IX deficiency) who are currently using the therapy of factor IX prophylaxis or have a history of life-threatening bleeding or repeated severe episodes of spontaneous bleeding.

“Gene therapy for haemophilia has been on the horizon for more than two decades. Despite advances in the treatment of hemophilia, prevention and treatment of bleeding episodes can negatively impact people’s quality of life,” said Peter Marks, MD, Ph.D., director of the Center for Biologics Evaluation and Research of the FDA. “Today’s approval provides a new treatment option for patients with haemophilia B and represents an important advance in the development of innovative therapies for those suffering from the high disease burden associated with this form of haemophilia.”

Hemophilia B is a genetic bleeding disorder resulting from missing or insufficient levels of blood clotting factor IX, a protein needed to produce blood clots to stop bleeding. Symptoms may include prolonged or heavy bleeding after an injury, surgery, or dental procedure; in severe cases, bleeding episodes may occur spontaneously with no clear cause. Prolonged bleeding episodes can lead to serious complications, such as bleeding into joints, muscles or internal organs, including the brain.

Most people who have hemophilia B and experience symptoms are men. The prevalence of hemophilia B in the general population is approximately one in 40,000; Hemophilia B accounts for approximately 15% of patients with hemophilia. Many women who are carriers of the disease have no symptoms. However, it is estimated that 10-25% of female carriers have mild symptoms; in rare cases, women may have moderate or severe symptoms.

Treatment typically involves replacing the missing or deficient clotting factor to improve the body’s ability to stop bleeding and promote healing. Patients with severe haemophilia B typically require a routine treatment regimen of intravenous (IV) infusions of factor IX replacement products to maintain sufficient clotting factor levels to prevent bleeding episodes.

Hemgenix is ​​a one-time gene therapy product given as a single dose by intravenous infusion. Hemgenix consists of a viral vector that carries a gene for coagulation factor IX. The gene is expressed in the liver to produce the protein Factor IX, to increase blood levels of Factor IX and thus limit bleeding episodes.

The safety and efficacy of Hemgenix were evaluated in two studies involving 57 adult men aged 18 to 75 years with severe or moderately severe haemophilia B. Efficacy was established based on the decrease in male annualized bleeding rate (ABR). In one study, which had 54 participants, subjects had increased factor IX activity levels, less need for routine factor IX replacement prophylaxis, and a 54% reduction in ABR from baseline.

The most common adverse reactions associated with Hemgenix included elevations in liver enzymes, headache, mild infusion-related reactions, and flu-like symptoms. Patients should be monitored for infusion adverse reactions and elevations of liver enzymes (transaminitis) in the blood.

This question has received Priority Review, Orphan, and Breakthrough Therapy designations.

The FDA has granted approval of Hemgenix to CSL Behring LLC.


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The FDA, an agency within the United States Department of Health and Human Services, protects public health by ensuring the safety, efficacy, and safety of human and veterinary drugs, vaccines, and other biological products for human and medical devices. The agency is also responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that emit electronic radiation, and regulation of tobacco products.