Hemophilia B Adult Gene Therapy Gets First Approval

The adeno-associated virus vector-based gene therapy Hemgenix (etranacogene dezaparvovec) from UniQure has received FDA approval for the treatment of people with haemophilia B. (congenital Factor IX deficiency).

For more than 20 years, gene therapy has been considered a potential treatment for hemophilia. The prevention and treatment of bleeding episodes can negatively affect a person’s quality of life, according to Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, despite breakthroughs in hemophilia therapy. “Today’s approval offers a new therapeutic option for Hemophilia B patients and represents a significant advancement in the development of novel medicines for those suffering from a high burden of disease related to this kind of hemophilia,” according to the statement.

Blood clotting factor IX, a protein required to build blood clots to halt bleeding, is either absent or present in insufficient amounts in people with hemophilia B, a genetic bleeding condition. After an injury, surgery, or dental operation, there may be prolonged or substantial bleeding as a symptom. In more serious circumstances, spontaneous bleeding episodes may happen without a known reason. Serious problems, such as bleeding into joints, muscles, or internal organs, including the brain, can result from protracted bleeding episodes.

Hemophilia B affects 15% of hemophilia sufferers.

Hemophilia B symptoms and development are more likely in men than in women. About 15% of hemophilia patients have hemophilia B, which has a prevalence of one in 40,000 in the general population. A large number of female carriers of the disease don’t show any symptoms. Female carriers may, however, develop mild symptoms in 10–25% of cases; moderate or severe symptoms in women are regarded to be extremely rare.

In order to strengthen the body’s capacity to stop bleeding and encourage healing, the clotting factor that is inadequate or lacking is routinely replaced. To maintain enough clotting factor to stop bleeding episodes, patients with severe hemophilia B often need a routine treatment schedule of intravenous (IV) infusions of Factor IX replacement medicines.

Hemgenix is a one-time intravenous infusion-based gene therapy treatment. It consists of a viral vector that contains the gene for clotting factor IX. The gene is expressed in the liver to produce Factor IX protein, increase blood levels of Factor IX, and stop bleeding episodes.

The drug will reportedly be sold for $3.5 million for a single dose by the Australian business CSL.

The safety and effectiveness of Hemgenix were investigated in two studies including 57 adult men with severe or moderately severe hemophilia B, aged 18 to 75. Effectiveness was assessed based on reductions in the annualized bleeding rate in men (ABR). In a study involving 54 individuals, it was discovered that the participants had higher levels of Factor IX activity, required less frequent Factor IX replacement prophylaxis, and had a 54% decrease in ABR from baseline.

Hemgenix was associated with a number of side effects, but the most frequent ones were liver enzyme increases, headaches, minor infusion-related responses, and flu-like symptoms. Blood liver enzyme increases (transaminitis) and unfavorable infusion reactions should be watched in patients.