Bristol Myers Squibb and Johnson & Johnson halted a Phase III trial of their factor XIa inhibitor milvexian after an interim analysis showed the study was unlikely to meet its primary endpoint in acute coronary syndrome. The sponsor teams stopped the trial for futility and will reassess development plans across the molecule’s remaining indications. Milvexian had been a leading candidate among next‑generation anticoagulants designed to reduce bleeding risk while preventing thrombosis. The failure in a high‑profile cardiovascular indication raises questions about the clinical viability of selective factor XIa inhibition as a broadly applicable strategy. Sponsors will review data to determine whether other ongoing milvexian programs can continue and whether biomarker or patient‑selection strategies might salvage development.