Mechanism of Action of Factor XI Inhibitors

In this episode, “Mechanism of Action of Factor XI Inhibitors,”Eva Mistry, MD explores the following question:

1. Asundexian is most far along of all investigational Factor XI inhibitors. Can you talk about mechanism of action of factor XI inhibitors?

Factor XI inhibitors are exciting because of where factor XI sits in the coagulation pathway: it is important for thrombosis but not essential for normal hemostasis after vascular injury. Unlike traditional anticoagulants (e.g., factor Xa or thrombin inhibitors), blocking factor XIa can inhibit pathologic clot formation without significantly impairing formation of the initial hemostatic plug, thereby reducing bleeding risk. Mechanistically, tissue factor–driven hemostasis proceeds largely independent of factor XI, while thrombosis amplification depends on factor XIa, allowing “uncoupling” of thrombosis from hemostasis. Several therapeutic strategies are being pursued—short half‑life small molecules (most flexible) and longer-acting monoclonal antibodies—with early phase 2 data showing antithrombotic efficacy without excess major or intracranial bleeding, now being tested in large phase 3 trials.

The next episode in this series, “Asundexian and Study Design of OCEANIC-STROKE Trial for Secondary Stroke Prevention,” features the panelists advancing their conversation on phase 3 trial of factor Xia inhibitor, asundexian, for secondary stroke prevention.