- Question
- Does factor XI inhibition with abelacimab cause less bleeding than a direct oral anticoagulant (rivaroxaban) in patients with atrial fibrillation?
- Design
- Phase 2, randomized 1:1:1 trial with blinded abelacimab and open-label rivaroxaban, enrolling 1287 patients. Median age was 74 years and 44% were women. The trial was stopped early on the recommendation of the independent data monitoring committee.
- Population
- Patients with atrial fibrillation and a moderate-to-high risk of stroke.
- Intervention
- Subcutaneous abelacimab once monthly, at a dose of 150 mg or 90 mg.
- Control
- Oral rivaroxaban 20 mg once daily, open-label (with dose reduction to 15 mg in patients with creatinine clearance â€50 ml/min per the registry).
- Primary outcome
- Major or clinically relevant nonmajor bleeding.
- Results
- The incidence of the primary end point was 3.2 events per 100 person-years with abelacimab 150 mg and 2.6 with abelacimab 90 mg, versus 8.4 with rivaroxaban (HR 0.38; 95% CI 0.24 to 0.60 for 150 mg; HR 0.31; 95% CI 0.19 to 0.51 for 90 mg; P<0.001 for both comparisons). At 3 months, free factor XI was reduced by a median of 99% with 150 mg and 97% with 90 mg.
- Safety
- The incidence and severity of adverse events appeared similar across the three groups.
- Conclusion
- In patients with atrial fibrillation at moderate-to-high stroke risk, abelacimab markedly lowered free factor XI levels and caused fewer bleeding events than rivaroxaban.
- Why it matters
- It provides evidence that blocking factor XI may allow anticoagulation with a lower bleeding risk than direct oral anticoagulants, supporting further development of this strategy, although this is a phase 2 trial focused on safety.
Card generated automatically with AI from the abstract of the original publication and the trial registry; every figure was checked against those sources. It may contain errors: verify the data at the source before using it for clinical decisions.
Generated on October 14, 2026