Hympavzi Approved for Hemophilia A or B Without Inhibitors
Pfizer announced that the U.S. Food and Drug Administration (FDA) approved Hympavzi™ (marstacimab-hncq) on Oct. 11, 2024, for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and pediatric patients 12 years of age and older with hemophilia A (congenital factor VIII deficiency) without factor VIII (FVIII) inhibitors, or hemophilia B (congenital factor IX deficiency) without factor IX (FIX) inhibitors. Hympavzi is a monoclonal antibody that reduces the activity of an anti-tissue factor pathway inhibitor (TFPI), a protein that keeps blood from clotting. Rather than replacing the clotting factors, Hympavzi increases the availability of thrombin, which further regulates blood clotting. It is the first once-weekly subcutaneous (SC) prophylactic treatment for hemophilia B. It is the first to be administered via a pre-filled pen or syringe for hemophilia A or B. The recommended dosing is a 300mg SC loading dose followed by 150mg SC once weekly. The launch date isn’t known at this time. Prescribing information is available here.
At a Glance
- Brand Drug: Hympavzi™ (marstacimab-hncq)
- Manufacturer: Pfizer
- Date Approved: Oct. 11, 2024
- Indication: Routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and pediatric patients 12 years of age and older with hemophilia A (congenital factor VIII deficiency) without factor VIII (FVIII) inhibitors, or hemophilia B (congenital factor IX deficiency) without factor IX (FIX) inhibitors.
- Dosage Forms Available: 150mg/mL single-dose pre-filled syringe or pen.
- Launch Date: Launch information is not yet available.
- Estimated Annual Cost: Pricing information is not yet available.
- Hemophilia, which includes several inherited bleeding disorders, results from genetic mutations. Hemophilia A is caused by insufficient activity of coagulation factor VIII, while hemophilia B results from deficiencies of factor IX. Either form of the condition involves excessive bleeding episodes that cause intense pain, permanent joint damage, and potentially life-threatening hemorrhages.
- Hemophilia A is the more common type of the condition, affecting around 25,000 patients – mostly boys and men – in the U.S. Up to 7,500 American patients, also including a few females, are estimated to have hemophilia B. The average patient age is about 24 years old, and approximately 40% of patients have severe forms of hemophilia.
- The phase III BASIS trial demonstrated that prophylactic treatment with marstacimab resulted in a statistically significant and clinically relevant reduction in annualized bleeding rate (ABR) in people living with severe hemophilia A and moderately severe to severe hemophilia B without inhibitors. In those treated with on-demand factor replacement intravenous (IV) therapy, marstacimab demonstrated superiority (P<0.0001) with a 92% reduction in bleeds. The results also showed superiority (p=0.0376) with marstacimab compared to prophylaxis, with a 35% reduction in ABR.
- Hympavzi comes with warnings and precautions about thromboembolic events, hypersensitivity, and embryofetal toxicity. The most common side effects of Hympavzi are injection site reactions, headache, and itching.
- Patients who have hemophilia A infuse one of several factor VIII replacement products IV once every few days to prevent bleeds and as needed to stop excessive bleeding that already has started. Hemlibra® (emicizumab-kxwh) may be used to prevent or reduce the frequency of bleeding episodes for adult and pediatric patients who have hemophilia A with or without inhibitors. BioMarin’s Roctavian™ (valoctocogene roxaparvovec-rvox) is a hemophilia A gene therapy that was approved for the treatment of adult patients with severe hemophilia A.
- Hemophilia B episodes are prevented by regular and treated by on-demand IV infusions of a factor IX replacement product. Hemgenix® (etranacogene dezaparvovec – drlb) and Beqvez™ (fidanacogene elaparvovec-dzkt) are two gene therapies approved to treat certain adults with hemophilia B.
- Novo Nordisk’s concizumab is another anti-tissue factor pathway inhibitor (TFPI). It is expected to be approved by Dec. 20, 2024, for the prevention and treatment of bleeding in patients 12 years and older with hemophilia A and B with inhibitors. An expanded approval for patients without inhibitors is expected next summer. Novo Nordisk’s Mim8 is a bi-specific monoclonal antibody that targets activated factor IX (FIXa) and factor X (FX) (similar to Hemlibra) that is in phase III development to prevent bleeding episodes in patients with hemophilia A. Approval is possible in 2026.