Study: Pfizer Hemophilia Drug Reduces Bleeding Rates

    Photo: Wikimedia Commons

    The Facts

    • On Tuesday, US drugmaker Pfizer announced the results of a late-stage study for its experimental hemophilia therapy, marstacimab, claiming that the drug reduced bleeding rates in patients with severe hemophilia A and moderately severe to severe hemophilia B without inhibitors.

    • The phase 3 BASIS clinical trial of the under-the-skin therapy, which blocks the anticoagulant protein known as tissue factor pathway inhibitor (TPFI), reportedly demonstrated superiority compared to prophylaxis and on-demand factor replacement therapies, reducing bleeding by 35% and 92%, respectively.

    The Spin

    Narrative A

    This study's results are promising and could be the first step towards Pfizer's marstacimab revolutionizing treatment for patients with hemophilia A or B. These results suggests the drug could prevent excessive bleeds and reduce treatment burden through once-weekly, under-the-skin administration.

    Narrative B

    While the experimental therapy is undeniably innovative — as it reduces the amount of anticoagulation instead of addressing the factor deficiency — TFPI blockers in marstacimab can cause clotting episodes that do not usually show up in small studies. The medical community should not get too excited about this development too soon.

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