Pfizer reports patient death in hemophilia trial for Hympavzi

Pfizer (PFE) on Tuesday announced that a patient who was taking part in a long-term extension trial for its hemophilia therapy Hympavzi (marstacimab) died after serious adverse events.

The patient with hemophilia A died in December following serious adverse events of cerebellar infarction and subsequent cerebral hemorrhage, Pfizer (PFE) said, adding that further investigations are ongoing to understand the events that led to his death.

In 2024, the U.S. FDA approved Hympavzi as a once-weekly subcutaneous prophylactic treatment to prevent or reduce the frequency of bleeding episodes in people with hemophilia A or B, a group of rare genetic blood disorders.

The New York-based company was evaluating the drug’s long-term safety and efficacy in hemophilia patients who had completed its BASIS and BASIS KIDS Phase 3 trials. The patient in question had completed the BASIS trial in 2022 before entering the long-term extension study a year later, according to Pfizer (PFE).