Factor XI inhibition in cardiovascular disease.

Cardiovascular disease remains the leading global cause of mortality, requiring effective antithrombotic strategies to prevent thromboembolic events. Currently available therapies are effective but have inherent bleeding risks which may limit or preclude their use, particularly in patients at the highest risk of bleeding. Factor XI (FXI) inhibitors are a promising new class of anticoagulants which may mitigate the risk of bleeding while maintaining efficacy. Further, they have the potential to provide effective anticoagulation in indications where direct oral anticoagulants (DOACs) are proven less effective than vitamin K antagonists (VKAs) or when DOACs are contraindicated. The development of FXI inhibitors was based on mechanistic considerations suggesting FXI's role in thrombus formation without significantly affecting hemostasis, supported by epidemiological data and animal experiments. FXI inhibitors, including antisense oligonucleotides, monoclonal antibodies, and small‑molecule inhibitors, target different stages of FXI production or activation, offering a diversity of therapeutic options with differing onset and offset of action, drug interaction potential, and renal elimination. FXI inhibitors have shown potential benefits in phase II trials, demonstrating similar or reduced bleeding rates to existing agents, including DOACs. The early termination of AZALEA‑TIMI 71 (Safety and Tolerability of Abelacimab [MAA868] vs Rivaroxaban in Patients With Atrial Fibrillation) and OCEANIC‑AF (A Study to Learn How Well the Study Treatment Asundexian Works and How Safe it is Compared to Apixaban to Prevent Stroke or Systemic Embolism in People With Irregular and Often Rapid Heartbeat [Atrial Fibrillation], and at Risk for Stroke) trials underscores challenges in the selection of appropriate patient populations and anticoagulant class, agent, and dose. Ongoing phase III trials including OCEANIC‑STROKE (A Study to Test Asundexian for  Preventing a Stroke Caused by a Clot in Participants After an Acute Ischemic Stroke or After a High‑risk Transient Ischemic Attack, a So‑called Mini Stroke) and LIBREXIA trials aim to further explore the efficacy of FXI inhibitors in stroke, acute coronary syndrome, and atrial fibrillation. In conclusion, FXI inhibitors hold promise as next‑generation anticoagulants, potentially addressing limitations of current therapies. Ongoing research is required to establish their place in clinical practice and address unresolved questions.