FDA approves Pfizer's antibody treatment for hemophilia

On Friday, Pfizer received FDA approval for Hympavzi (marstacimab-hncq) as a routine treatment to prevent and reduce the frequency of bleeding episodes in adults and adolescents with hemophilia A or B without inhibitors. This approval makes Hympavzi the first hemophilia drug to be delivered subcutaneously once a week, requiring minimal preparation to administer the dose to patients.

The FDA’s decision was based on data from a phase 3 clinical trial, where Hympavzi demonstrated a significant reduction in bleeding compared to routine preventive methods and on-demand treatments currently available for patients with hemophilia A or B.

“The approval of Hympavzi is a meaningful advancement for people living with hemophilia A or B without inhibitors for bleed prevention, with a generally manageable safety profile and a straightforward once-weekly subcutaneous administration,” said Suchitra S. Acharya, Director of the Hemostasis and Thrombosis Center Northwell Health, and Program Head at the Cohen Children’s Medical Center. “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.”

Improving care for hemophilia patients​

Hemophilia englobes a group of genetic disorders that impair the blood’s natural ability to clot, increasing the risk of internal bleeding and long-term joint damage for the more than 800,000 people affected around the world. These conditions are caused by mutations that result in low levels of proteins known as blood clotting factors. Hemophilia A is caused by a deficiency in clotting factor VIII while hemophilia B is caused by a deficiency in clotting factor IX.

Patients with hemophilia typically receive a replacement therapy, however, some of them can naturally develop antibody inhibitors against the replacement factors. Pfizer’s newly approved treatment is only intended for patients who have not developed these inhibitors. 

Hympavzi is the first and only approved treatment for hemophilia to target the tissue factor pathway inhibitor (TFPI), an anticoagulation protein that is naturally found in the blood that prevents the formation of blood clots. The drug is delivered through a user-friendly auto-injector pen, designed as a more convenient alternative to the periodic infusions required in traditional replacement therapy.

In the phase 3 BASIS clinical trial, which recruited 116 patients with hemophilia, Hympavzi was able to reduce the annualized bleeding rate by 35% compared to routine prophylaxis and by 92% compared to on-demand treatments during a year of treatment.

Approval in Europe could soon follow, as the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion for the antibody drug in September. Earlier this year, Pfizer was granted approval​ in the US, EU and Canada for Beqvez (fidanacogene elaparvovec), a gene therapy targeting hemophilia.

“Hympavzi is Pfizer’s second hemophilia treatment to receive FDA approval this year,” said Aamir Malik, Chief U.S. Commercial Officer and Executive Vice President at Pfizer. “We look forward to launching this latest medical breakthrough and to now offer three distinct classes of hemophilia medicines — an anti-TFPI, gene therapy, and recombinant factor treatments — that can meet the unique treatment needs of a wide range of patients.”