> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Pfizer BLA for Hemophilia Accepted for Review
- URL: https://www.fdaweb.com/pfizer-bla-for-hemophilia-accepted-for-review/
- Published: 2023-12-11T12:00:00.000Z
- Updated: 2026-09-14T14:18:12.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5155968

FDA has accepted for review a Pfizer BLA for its anti-tissue factor pathway inhibitor (anti-TFPI) candidate marstacimab for treating hemophilia A or hemophilia B without inhibitors to Factor VIII or Factor IX. The agency has set a user fee review action target date in the fourth quarter of 2024\. If approved, marstacimab is expected to become the “first once-weekly subcutaneous treatment for people living with hemophilia B and the first treatment administered as a flat dose for people living with hemophilia A or B,” the company says.

“For more than five decades, the most common treatment approach for hemophilia A and B has been factor replacement therapy, which replaces missing clotting factors to facilitate proper blood coagulation,” Pfizer says. “Marstacimab is a novel, investigational treatment for hemophilia that is designed to restore hemostasis by inhibiting TFPI.”

The submission is based on data from the Phase 3 BASIS trial ([NCT03938792](https://cts.businesswire.com/ct/CT?id=smartlink&url=https%3A%2F%2Fclinicaltrials.gov%2Fct2%2Fshow%2FNCT03938792%3Fterm%3DPF-06741086%26draw%3D2%26rank%3D2&esheet=53869370&newsitemid=20231211991010&lan=en-US&anchor=NCT03938792&index=2&md5=fa7db22fafc62a97ee772e77edd9f5c2&ref=fdaweb.com)) that were recently [presented](https://cts.businesswire.com/ct/CT?id=smartlink&url=https%3A%2F%2Fwww.pfizer.com%2Fnews%2Fpress-release%2Fpress-release-detail%2Fmarstacimab-phase-3-data-presented-ash-2023-demonstrate&esheet=53869370&newsitemid=20231211991010&lan=en-US&anchor=presented&index=3&md5=ff5f948d793a8d7ce9b473af687ad35c&ref=fdaweb.com) at the American Society of Hematology annual meeting. The data showed that marstacimab reduced annualized bleeding rate by 35% and 92% compared to routine prophylaxis and on-demand treatment in patients with hemophilia A and B without inhibitors, respectively, according to the company.

Marstacimab is a monoclonal immunoglobulin G isotype, subclass 1 (IgG1) that targets the Kunitz 2 domain of TFPI, a natural anticoagulation protein that functions to prevent the formation of blood clots, Pfizer says.