Oct. 14, 2024 – The FDA has approved a new preventive treatment for people with certain types of hemophilia that can reduce bleeding episodes, sometimes down to just a few per year.
Hemophilia is a rare blood clotting disorder that can lead to prolonged bleeding after an injury or surgery, as well as spontaneous bleeding in the muscles, joints, or organs. The new treatment, called Hympavzi, is for people ages 12 and older with hemophilia A or hemophilia B. Those are the two most common types of the condition and differ based on specific proteins involved in blood clotting.
The medicine is a once-per-week shot using a prefilled pen and offers an alternative to current preventive options that involve infusions several times per week. Its generic name is marstacimab.
“Today’s approval of Hympavzi provides patients with hemophilia a new treatment option that is the first of its kind to work by targeting a protein in the blood clotting process,” Ann Farrell, MD, director of the Division of Non-Malignant Hematology in the FDA’s Center for Drug Evaluation and Research, said in a statement. “This new type of treatment underscores the FDA’s commitment to advance the development of innovative, safe and effective therapies.”
Rather than helping the blood clot normally by adding clotting ability through infusions, Hympavzi works by reducing the amount of a naturally occurring protein that thins the blood. The body then has more of an enzyme called thrombin that is important for clotting, which ultimately leads to fewer bleeding episodes.
The approval is based on results of a clinical trial involving 116 men and boys, all of whom had hemophilia A or hemophilia B with severe symptoms, meaning they bleed after an injury and regularly have spontaneous bleeding without an obvious cause. For six months, 33 of them used standard on-demand treatments when they bled, and the other 83 used standard preventive treatments. Then, for the next 12 months, all of the people in the study took Hympavzi preventively.
The researchers compared the estimated annual number of treated bleeding episodes, during the six-month standard treatment period, to the annual rate when the people in the study took Hympavzi. On-demand standard treatment averaged the equivalent of 38 episodes per year, compared to 3.2 per year with Hympavzi, the FDA reported in its approval announcement.
Preventive standard treatments averaged the equivalent of 7.85 episodes per year, compared to 5.08 per year with Hympavzi. The FDA called that rate with Hympavzi “similar” to the rate with standard preventive treatments used in the study.
In a news release, drugmaker Pfizer said Hympavzi reduced the annual bleeding rate for treated bleeds by 35% among the group that initially took standard preventive treatments, and by 92% among the group that initially took on-demand treatments.
Side effects while using Hympavzi may include reactions where the needle goes in, headache, and itching. The FDA also noted that people using Hympavzi need to consider warnings and precautions about circulating blood clots (also called thromboembolic events), hypersensitivity, and potential toxic effects on a developing embryo or fetus.