Xisomab 3G3(Oregon Health & Science University)

Factor XI/XIa (FXI/XIa) has emerged as a potential target for antithrombotic therapy, driven by preclinical evidence showing the role of FXI/XIa inhibition for preventing thrombosis without impeding hemostasis. This is particularly promising for patients at high risk of both thromboembolic events and bleeding, such as patients with end-stage kidney disease (ESKD) on hemodialysis (HD).

We systematically searched Embase, MEDLINE, and ClinicalTrials.gov for randomized controlled trials evaluating FXI/XIa inhibitors in patients with ESKD on HD, without restricting inclusion to specific comparators or indications. Interventional treatment arms were pooled, and study results were synthesized by fitting random-effects models, calculating odds ratios (ORs) and 95% confidence intervals (CIs).

Five phases 2 studies encompassing 1270 participants were identified, investigating gruticibart, IONIS-FXI_Rx, osocimab, or fesomersen in the general HD population and using placebo as a comparator. Four studies were fully published and included in the meta-analysis. Use of FXI/XIa inhibitors was associated with an OR of 0.80 (95% CI = 0.47-1.35) for clinically relevant bleeding, 0.51 (95% CI = 0.21-1.28) for major bleeding, and 0.90 (95% CI = 0.49-1.68) for clinically relevant nonmajor bleeding. The ORs for thromboembolic events and all-cause mortality were 0.66 (95% CI = 0.28-1.56) and 0.46 (95% CI = 0.15-1.40), respectively.

Currently available evidence does not indicate a significantly increased bleeding risk of FXI/XIa inhibitors in patients with ESKD on HD compared to placebo. Their efficacy and their association with all-cause mortality need to be investigated in sufficiently powered, randomized controlled phase 3 trials.

Significant advancements have shaped the landscape of anticoagulant therapy in the past two decades, including the introduction of direct oral anticoagulants (DOACs), characterized by favorable safety and efficacy profiles and reduced drug-to-drug or food interaction resulting in excellent patient compliance. However, residual concerns still exist with standard-of-care anticoagulant therapy, including the inability to use DOACs in several clinical settings and the need to further reduce the risk of bleeding. Recent improvements in the understanding of the mechanisms behind thrombus formation have led to the awareness that the intrinsic pathway of the coagulation cascade may play an important role in pathological thrombosis, but not in hemostasis. This has represented the rationale for targeting this pathway with factor XI (FXI) inhibitors, with the aim of uncoupling hemostasis and thrombosis. Clinical evidence from patients with FXI deficiency further supports this concept. A number of compounds with different mechanisms of action have been developed to target FXI (i.e., asundexian, abelacimab, Ionis-FXIRx, milvexian, osocimab, and Xisomab 3G). To date, the majority of available trials have not gone beyond completion of phase 2 and results are conflictive making it difficult to appraise the clinical benefit of these compounds in the different clinical settings where they have been tested (i.e., atrial fibrillation, acute ischemic stroke, acute myocardial infarction, end-stage renal disease, total knee arthroplasty). Moreover, the largest phase 3 randomized trial designed to test the efficacy of asundexian over apixaban in patients with atrial fibrillation, the OCEANIC-AF, has been prematurely stopped as a result of the inferior efficacy of asundexian. In this review we discuss the pharmacological properties and available evidence generated thus far for factor XI inhibitors, providing a perspective on the current state of these drugs.