Hympavzi now approved in UK for prevention of hemophilia bleeds
Therapy OK'd for both hemophilia A and B patients ages 12 and older
The U.K.’s Medicines and Healthcare products Regulatory Agency (MHRA) has approved Hympavzi (marstacimab) for the prevention of bleeding episodes in people with both hemophilia A and hemophilia B, ages 12 and older.
The therapy, already approved in the U.S. and the European Union, is designed to prevent or reduce the frequency of bleeds and can be administered by caregivers or patients following adequate training.
To be eligible for Pfizer’s injectable therapy, patients in the U.K. must weigh at least 35 kg, or 77 pounds, and should not have inhibitors, or neutralizing antibodies that can render standard factor replacement therapies less effective, per a press release from the regulatory agency.
Hympavzi is now being reviewed by the National Institute for Health and Care Excellence, which will inform whether the treatment’s cost will be covered under England’s public health insurance program.
The therapy, which targets a protein called tissue factor pathway inhibitor (TFPI), is the first of its kind to be approved for this indication, per the MHRA.
“This new type of treatment demonstrates our commitment to enabling access to safe, innovative and effective medicines,” said Julian Beach, MHRA’s interim executive director, healthcare quality and access.
Hympavzi approval supported by Phase 3 BASIS trial data
People with hemophilia experience excessive, prolonged, and/or spontaneous bleeding episodes due to a lack of functional blood clotting proteins — namely factor VIII, or FVIII, in hemophilia A, and factor IX, called FIX, in hemophilia B.
The standard of care treatment for either type of hemophilia is factor replacement therapy to supply the body with a version of the missing clotting factor. This is done via frequent infusions given into the bloodstream. While effective, preparation and treatment can be challenging and time-consuming, placing a substantial burden on patients and caregivers.
Hympavzi is given as a once-weekly, under-the-skin (subcutaneous) injection using a convenient prefilled syringe or pen. It requires minimal preparation and is easy to administer. Patients or caregivers can inject the therapy after receiving proper training from healthcare professionals.
The therapy’s active ingredient, marstacimab, is an antibody designed to block TFPI, a protein that normally prevents blood from clotting excessively. In doing so, the treatment helps promote clotting to prevent bleeds in people with hemophilia A or B.
Hympavzi’s approvals were supported by data from the ongoing Phase 3 BASIS trial (NCT03938792), which evaluated the therapy in men and boys, ages 12-74, with severe hemophilia A or moderately severe to severe hemophilia B, with or without inhibitors.
Among the 116 trial participants without inhibitors, a year of weekly treatment with Hympavzi was associated with reductions in annual treated bleed rates compared with a six-month run-in period during which patients had received standard of care preventive or on-demand replacement therapy.
Specifically, mean rates for treated bleeds dropped by 35% compared with preventive replacement therapy, and by 92% relative to on-demand treatment. Data from participants with inhibitors are expected this year.
Extension continuing to track safety of hemophilia prevention therapy
The most common adverse events reported after Hympavzi treatment were injection site reactions, headache, high blood pressure, and itching, according to the therapy’s label. Patients who have had previous allergic reactions to Hympavzi or its ingredients shouldn’t use it.
“Keeping patients safe and enabling their access to high quality, safe and effective medical products are key priorities for us,” Beach said. “As with all products, we will keep its safety under close review.”
Safety and efficacy data will continue to be collected in an ongoing open-label extension (NCT05145127), in which participants who completed BASIS are receiving Hympavzi for up to seven years. Interim data have suggested the therapy has sustained benefits over time.
Meanwhile, another Pfizer-sponsored Phase 3 study called BASIS KIDS (NCT05611801) is testing the safety and efficacy of weekly Hympavzi in children, ages 1-17, with severe hemophilia A or moderately severe to severe hemophilia B, with or without inhibitors. Participants who complete BASIS KIDS are also eligible to enroll in the open-label extension study.
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