A patient enrolled in a long-term follow-up clinical trial of Pfizer’s hemophilia A therapy Hympavzi has died, according to a letter released by the company. The death occurred on December 14 during an extension phase of a Phase III study that began in 2022. The patient had been receiving Hympavzi as a preventive treatment, along with recombinant factor VIIa, following minor surgery.
Pfizer reported that the patient experienced serious adverse events, including a stroke and bleeding in the brain. The company stated it is working with the data monitoring committee to investigate the circumstances and is considering co-existing medical conditions and other medications taken by the patient at the time.
Hympavzi received approval from U.S. regulators in October 2024 for use as a once-weekly subcutaneous prophylactic injection in patients with hemophilia A or B who do not have inhibitors. The drug has also been authorized for use in Europe. Hympavzi is an IgG1 monoclonal antibody designed to target the Kunitz domain 2 of tissue factor pathway inhibitor protein, aiming to improve blood clotting for people with hemophilia.
Earlier this year, Pfizer discontinued its hemophilia gene therapy Beqvez globally due to low patient demand and shifted focus to Hympavzi. Beqvez was developed in partnership with Sangamo Therapeutics. In September 2024, Pfizer also withdrew its sickle cell disease therapy Oxbryta from the market after new safety data revealed an increased risk of death and complications among treated patients.
"Pfizer said it is working with the data monitoring committee to gather information about the death. The company noted co-existing medical conditions and other medications the patient was taking at the time."
