On Feb. 11, 2025, Novartis announced an agreement to acquire Anthos Therapeutics, a Boston-based, privately held, clinical-stage biopharmaceutical company with abelacimab, a late-stage medicine in development for the prevention of stroke and systemic embolism in patients with atrial fibrillation.

Anthos Therapeutics, launched by Blackstone Life Sciences and Novartis in 2019, has advanced abelacimab through clinical development under a license from Novartis. Abelacimab is a novel, highly selective, fully human monoclonal antibody designed to induce effective hemostasis-sparing anticoagulation through Factor XI inhibition.

Phase 2 data showed a significant reduction in bleeding events in patients taking abelacimab versus a standard of care direct-oral anticoagulant in patients with atrial fibrillation (AZALEA). Three Phase 3 clinical trials are ongoing for patients at risk of arterial and venous clots, one in patients with atrial fibrillation (LILAC-TIMI 76) and two in cancer associated thrombosis (ASTER) and (MAGNOLIA).

Under the terms of the agreement, Novartis will make an upfront payment of USD 925 million upon closing of the transaction, subject to certain customary adjustments, and potential additional payments of up to USD 2.15 billion upon achievement of specified regulatory and sales milestones. The transaction is expected to close in the first half of 2025, subject to satisfaction of customary closing conditions.