The approval makes Pfizer’s Hympavzi the first once-weekly subcutaneous prophylactic injection for hemophilia B in the U.S., according to the company, which is currently embroiled in a row with activist investor Starboard Value.
The FDA on Friday signed off on Pfizer’s marstacimab-hncq for the treatment of hemophilia A or hemophilia B in adults or adolescents, which will now be marketed under the brand name Hympavzi.
Friday’s approval makes Hympavzi the first once-weekly subcutaneous prophylactic injection for hemophilia B in the U.S., according to Pfizer’s announcement. Hympavzi is also the first treatment available through a pre-filled pen or syringe for both hemophilia A and hemophilia B.
According to its label, Hympavzi is indicated for routine prophylaxis to lower the frequency or completely prevent bleeding episodes in hemophilia patients. The treatment is administered once a week via subcutaneous injection and is approved for hemophilia A patients without factor VIII inhibitors or hemophilia B patients without factor IX inhibitors.
Suchitra Acharya, program head of the Bleeding Disorders and Thrombosis Program at Cohen Children’s Medical Center, in a statement called Hympavzi’s approval a “meaningful advancement for people living with hemophilia A or B,” many of whom continue to suffer from persistent bleeding and experience difficulties in managing their conditions despite progress in the field.
“Hympavzi aims to reduce the current treatment burden by meeting an important need for these patients, including many who have required frequent, time-consuming intravenous treatment infusion regimens,” according to Acharya, who previously disclosed receiving honoraria from Pfizer.
The approval was backed by data from the Phase III BASIS trial, an open-label study that enrolled nearly 190 patients with severe hemophilia A or moderately severe to severe hemophilia B. Pfizer posted data from BASIS in May 2023, touting a 92% reduction in bleeding in patients lacking inhibitors to factor VIII or factor IX. Annual bleeding rate dropped by 35%.
Hympavzi is an IgG1 monoclonal antibody that targets the Kunitz domain 2 of the tissue factor pathway inhibitor protein, which under healthy circumstances prevents blood clotting. This mechanism of action allows Hympavzi to enhance coagulation in hemophilia patients.
Friday’s regulatory win bolsters Pfizer’s hemophilia portfolio, anchored by the gene therapy Beqvez, which won the FDA’s green light in April 2024 for moderate to severe hemophilia B. The company is also developing another gene therapy, giroctocogene fitelparvovec, for hemophilia A. Phase III data released in July 2024 showed that the investigational treatment was both non-inferior and superior to regular Factor VIII infusions.
Hympavzi’s approval comes as Pfizer continues to grapple with activist investor Starboard Value which last week took a $1 billion stake in the pharma, hoping to depose CEO Albert Bourla and shake up the direction of the company. However, former Pfizer CEO Ian Read and former CFO Frank D’Amelio reaffirmed their support for the company’s current leadership.
Starboard Value in a letter to Pfizer’s board claimed Read and D’Amelio were pressured to issuing a statement of support for Bourla and senior management.
