Bristol Myers Squibb and Johnson & Johnson Discontinue Phase 3 Librexia ACS Trial for FXIa Inhibitor Milvexian

▎Armstrong

On November 14, 2025, Bristol-Myers Squibb and Johnson & Johnson announced the termination of the Phase III clinical trial Librexia ACS for the FXIa inhibitor Milvexian. This decision was made by the IDMC following an interim analysis, as the study was unlikely to meet its primary endpoint for efficacy.

Bristol-Myers Squibb's stock price fell 4% on the day, with a current market value of $95 billion.

Factor FXI may be a more ideal anticoagulant target. Factor FXI mainly participates in the positive feedback amplification stage of the intrinsic pathway during the coagulation process, while physiological hemostasis primarily occurs through the extrinsic pathway.

Summary

The competition for drug development targeting FXI is particularly intense, covering various drug formats such as antibodies, small molecules, ASO, and siRNA. Bayer, as well as Bristol-Myers Squibb/Johnson & Johnson's small molecule inhibitors, have successively failed in Phase III clinical trials. Novartis acquired Anthos to reclaim the FXI antibody and continues to advance into Phase III clinical trials. In comparison, siRNA is expected to achieve a longer dosing cycle, making it suitable for chronic disease management applications. Sirius Therapeutics' SRSD-107Currently in Phase II clinical trials in Europe, and has reached a licensing and collaboration agreement with CRISPR Therapeutics.

Sirius Therapeutics FXI siRNA and CRISPR Therapeutics adopt a 50:50 co-development model, receiving $25 million in cash, $70 million in equity, and $800 million in milestone payments.