Pfizer Seeks Label Expansion For Hemophilia Drug After Promising Data

Pfizer Inc. PFE released topline results from the Phase 3 BASIS study evaluating Hympavzi (marstacimab) for adults and adolescents living with hemophilia A or B with inhibitors.

Phase 3 BASIS study in patients without inhibitors supported the FDA approval of Hympavzi in October 2024.

The study met the primary endpoint and key secondary bleeding endpoints, demonstrating the superiority of once-weekly subcutaneous Hympavzi in improving key bleeding outcomes compared to on-demand treatment in a patient population where less burdensome treatment approaches are needed.

Also Read: FDA Approves Sanofi’s Hemophilia Drug

The BASIS trial demonstrated that prophylactic treatment with Hympavzi resulted in a statistically significant and clinically relevant reduction in annualized bleeding rate (ABR) of treated bleeds in people with severe hemophilia A or B with inhibitors.

Forty-eight people living with hemophilia were treated with Hympavzi during 12 months versus an on-demand intravenous regimen with bypassing agents, administered as part of usual care in the six-month lead-in period.

Hympavzi was superior to on-demand treatment with a 93% reduction in ABR over 12 months (ABR 1.39 vs ABR on-demand 19.78; p < 0.0001).

The superiority of Hympavzi was also demonstrated across all bleeding-related secondary endpoints, spontaneous bleeds, joint bleeds, target joint bleeds, and total bleeds, Pfizer announced on Thursday.

Hympavzi was generally well-tolerated, consistent with the non-inhibitor cohort of the BASIS study and Phase 1/2 results. No deaths or thromboembolic events were reported.

Analyses of the full Phase 3 dataset from the inhibitor cohort of the BASIS study are ongoing, and additional data will be presented at upcoming medical meetings.

Hympavzi’s mechanism of action is differentiated from those of FVIII and FIX replacement treatments. Instead of replacing missing or insufficient clotting factors, Hympavzi is intentionally designed to target tissue factor pathway inhibitor (TFPI), one of the body’s natural mechanisms that inhibits the initiation of blood clotting.

By targeting the Kunitz 2 domain of TFPI, Hympavzi may help re-establish balance between bleeding and blood clot formation. Its goal is to offer a combination of bleed protection, good tolerability, and straightforward administration.

Pfizer plans to discuss these data with regulatory authorities to initiate regulatory filings for Hympavzi for hemophilia patients with inhibitors.

Price Action: PFE stock is trading lower by 0.05% to $24.25 at last check Thursday

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