Antithrombotic Effects of the Novel Small-Molecule Factor XIa Inhibitor Milvexian in a Rabbit Arteriovenous Shunt Model of Venous Thrombosis

Milvexian: An Oral, Bioavailable Factor XIa Inhibitor

Direct oral anticoagulants have a dose-dependent increased bleeding risk which limits use in certain populations. Studies in both animals and humans with inherited variations in factor XI levels provide a theoretical basis for a drug target capable of addressing current unmet needs. Milvexian is an oral factor XIa inhibitor that has the potential to provide robust anticoagulant effect without increased bleeding compared with current standard of care. Several key studies in the preclinical, phase I, and phase II stages have reported promising safety data in venous thromboembolism and stroke prevention without compromising hemostasis. The planned phase III trials will examine the efficacy of milvexian for prevention of thrombotic events in patients with acute stroke, acute coronary syndrome, and atrial fibrillation.

Milvexian: evaluating the factor XIa inhibitor for the treatment of acute coronary syndrome

INTRODUCTION

Balancing the prevention of thrombosis with bleeding risk when combining anticoagulants and platelet antagonists remains a concern among clinicians, particularly in patients with acute coronary syndrome (ACS) who are treated with potent antiplatelet therapy. This may be because the available antiplatelet and anticoagulants are unable to uncouple physiological hemostasis and pathological thrombosis. Therefore, their use is associated with an unavoidable elevated risk of bleeding.

AREAS COVERED

Evidence available from studies evaluating FXIa inhibitors and milvexian was collected from a selective literature search. In this review, the authors describe the potential role of FXI/XIa in experimental thrombosis, evidence for FXIa inhibition in the treatment of clinical thrombotic events, and highlight the current evidence supporting the role of milvexian, a novel FXIa inhibitor, in patients with ACS.

EXPERT OPINION

The ongoing LIBREXIA-ACS trial is a large-scale study currently investigating milvexian in patients with ACS. This study may support the proof of concept of differentiating physiological hemostasis and pathological thrombosis and achieving maximum antithrombotic efficacy with minimum bleeding risk when used on top of dual antiplatelet therapy with potent P2Y12 receptor blockers.

Anticoagulants for atrial fibrillation: from warfarin and DOACs to the promise of factor XI inhibitors

Anticoagulation is the mainstay of stroke prevention in appropriate patients with atrial fibrillation. Due to advances in pharmacotherapy the anticoagulants used for this purpose have evolved significantly over the past decades with the aim of optimizing effectiveness while minimizing bleeding risks. Though significant improvements have been made toward this goal, bleeding risk remains the major concern with these therapies. An investigational class of agents which inhibit Factor XI have shown promise in pre-clinical and early clinical trials to significantly minimize bleeding while maintaining efficacy against stroke and systemic embolism. This mini-review will discuss anticoagulants currently used for stroke prevention in patients with atrial fibrillation including warfarin and direct oral anticoagulants. We will also review the mechanism of action and data from early clinical trials for Factor XI inhibitors and discuss their potential advantages and shortcomings.