Stroke-Associated Letal Outcome with Hympavzi: Michael Makris on Pfizer’s Announcement
Michael Makris, Emeritus Professor of Haemostasis and Thrombosis at the University of Sheffield, Editor-in-Chief of RPTH Journal, shared on LinkedIn:
”Important.
Pfizer has just announced that a person with hemophilia, in their marstacimab (Hympavzi) clinical trial program, has died from a thrombotic stroke.
I attach the letter they sent to a number of patient organisations including the World Federation of Hemophilia.
The information provided in the letter is minimal.
I hope they reach out to all hemophilia doctors worldwide who can potentially prescribe this drug to inform them about this event, and the other thrombotic event in the same clinical trial that was previously disclosed at the EAHAD and ISTH meetings.
The patient who died, had hemophilia A with an inhibitor.
Marstacimab is at present only approved for persons with hemophilia A and B without an inhibitor.”

Stay updated with Hemostasis Today.
-
Jul 12, 2026, 08:50Where the Hemophilia Community Comes Together at ISTH 2026 – EAHAD
-
Jul 12, 2026, 08:2210 Posts Not To Miss from ISTH 2026, Part 1
-
Jul 12, 2026, 07:58Brian O Mahony: Could NXT-007 Minimize the Need for Perioperative FVIII
-
Jul 12, 2026, 07:50Shayan Mohammadmoradi: Connecting the Next Generation of Hemostasis Researchers at ISTH 2026
-
Jul 12, 2026, 07:42Alexandra Yakusheva: ThrombInnov Debuts at ISTH 2026 with a Focus on Translational Research
-
Jul 12, 2026, 07:34Wolfgang Miesbach: ISTH 2026 Explores the Next Generation of APS Diagnostics
-
Jul 12, 2026, 07:28Sara Zalghout: ISTH 2026 Highlights Progress in Thromboinflammation Research
-
Jul 12, 2026, 07:13Ekaterina Balaian: Finding Healing Through Art at ISTH 2026
-
Jul 12, 2026, 06:59Maaike Sybil Jongen: Flow Cytometry for Platelet Phenotyping at ISTH 2026