FDA Approves Pfizer’s Hympavzi for Prophylaxis in Patients with Hemophilia A or B

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The FDA has approved Pfizer’s Hympavzi (marstacimab-hncq) for routine prophylaxis (RP) in adults and adolescents over 12 years of age with hemophilia A or B without inhibitors. Hympavzi is now the first and only anti-tissue factor pathway inhibitor (anti-TFPI) to be available in the United States for this indication. Additionally, Pfizer stated that it has introduced a convenient treatment option via a pre-filled, auto-injector pen with once-weekly subcutaneous dosing.¹

“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, MD, director, hemostasis and thrombosis center Northwell Health, program head, bleeding disorders, thrombosis program, Cohen Children’s Medical Center, in a press release. “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.”

The approval was based on results from the open-label, multicenter Phase III BASIS trial, which evaluated the efficacy and safety of Hympavzi in adults and adolescents over 12 years of age with severe hemophilia A or moderately severe to severe hemophilia B. Investigators enrolled 116 patients with hemophilia without inhibitors, all of whom were treated during a 12-month active treatment period versus an RP and intravenous regimen, administered as part of usual care in a six-month observational period. Secondary endpoints included superiority of Hympavzi across spontaneous bleeds, joint bleeds, target joint bleeds, and total bleeds.

Results found that Hympavzi reduced the annualized bleeding rate for treated bleeds by 35% and 92% after a 12-month active treatment period compared to RP and on-demand treatment, respectively. Common adverse events included injection site reactions and headaches, both of which were reported to be manageable. The safety profile for Hympavzi was also found to be consistent with Phase I/II results.¹

While the current number of people living with hemophilia in the United States is unknown, statistics from the Centers for Disease Control and Prevention suggest that it could be around 33,000, based on information from patients receiving care in federally funded hemophilia treatment centers between 2012 and 2018. Four out of 10 males have severe hemophilia, with hemophilia A being three to four times more common than hemophilia B.

Most individuals are first diagnosed at a young age, with a median age of 36 months for mild hemophilia, eight months of age for moderate hemophilia, and one month of age for severe hemophilia. In two-thirds of all cases, there is a family history of hemophilia, with the other one-third having no known history of the bleeding disorder. Approximately one in every five people with hemophilia A and three in every 100 people with hemophilia B will develop an inhibitor, which will prevent treatments meant to stop or prevent bleeding episodes.²

"The hemophilia community continually seeks advancements in care that can improve quality of life for our community members," said Phil Gattone, president, CEO, National Bleeding Disorders Foundation, in the press release. "We greatly appreciate Pfizer's innovative efforts in developing this novel treatment option that addresses some of the ongoing challenges faced by people with hemophilia A and B. The availability of this therapy represents a powerful step forward in advancing care for more individuals and families in the bleeding disorders community.”

References

1. U.S. FDA Approves Pfizer’s HYMPAVZI™ (marstacimab-hncq) for the Treatment of Adults and Adolescents with Hemophilia A or B Without Inhibitors. Pfizer. October 11, 2024. Accessed October 14, 2024. https://www.pfizer.com/news/press-release/press-release-detail/us-fda-approves-pfizers-hympavzitm-marstacimab-hncq

2. Data and Statistics on Hemophilia. CDC. Accessed October 14, 2024. https://www.cdc.gov/hemophilia/data-research/index.html