Key result
Abelacimab reduces major or clinically relevant bleeding ~74% vs. rivaroxaban in AF.
Why the study?
Recurrent bleeding with ongoing anticoagulation in AF is common and often prompts interruption or discontinuation of therapy, so the effect of the factor XI inhibitor abelacimab versus rivaroxaban on total bleeding events beyond the first bleed needed to be examined.
Does abelacimab reduce total bleeding events compared with rivaroxaban in patients with atrial fibrillation?
RCT (n=1,280)
1:1:1
Does abelacimab reduce total bleeding events compared with rivaroxaban in patients with atrial fibrillation?
In patients with atrial fibrillation, factor XI inhibition with abelacimab substantially reduces total, first, and recurrent major and clinically relevant non-major bleeding events compared with rivaroxaban.
Abelacimab may offer a lower-bleeding anticoagulation option in AF; extends first-event safety data to total and recurrent events in RCT.
Background Abelacimab, a novel factor XI inhibitor, significantly reduced the time to first major or clinically relevant non-major (CRNM) bleed compared with rivaroxaban in patients with atrial fibrillation (AF) in the AZALEA-TIMI 71 trial. Recurrent episodes of bleeding with ongoing anticoagulation are common and remain an important safety concern for patients and providers, often leading to anticoagulation interruption or even discontinuation. Purpose To examine the effect of abelacimab vs. rivaroxaban on total bleeding events in patients with AF. Methods AZALEA-TIMI 71 randomized patients with AF 1:1:1 to one of two abelacimab doses (90 or 150 mg SC monthly) or to rivaroxaban daily. For this analysis, both abelacimab doses were pooled. Outcomes of interest included major/CRNM bleeding (primary endpoint), major bleeding alone, major/CRNM GI bleeding, and major GI bleeding. Negative binomial regression was used to examine the effect of abelacimab vs. rivaroxaban on total bleeding events, with effect estimates summarized by the incidence rate ratio (IRR). Analyses were performed on-treatment, including events within 60 days of a dose of study drug. Results Among 1,280 patients (852 on abelacimab, 428 on rivaroxaban) followed for a median of 2.1 years, 113 first and 40 recurrent (ie, 35% additional) major/CRNM bleeds occurred for a total of 153 events. Compared to rivaroxaban, abelacimab reduced first major/CRNM bleeds by 65% (HR 0.35, 95% 0.24-0.51), recurrent bleeds by 92% (IRR 0.08, 95% CI 0.03-0.23) and total bleeds by 74% (IRR 0.26, 95% CI 0.17-0.39; p<0.001) (Figure 1). Abelacimab also reduced the rates of total major bleeding alone, major/CRNM GI bleeding, and major GI bleeding by 78%, 81% and 92%, respectively, vs. rivaroxaban (all p<0.001) (Figures 1-2). Conclusion Compared with rivaroxaban, abelacimab substantially reduces the totality of bleeding across a range of bleeding severity. These data further support the safety of FXI inhibition with abelacimab in minimizing the burden of anticoagulation-related bleeding in patients with AF.Figure 1Figure 2
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Patel et al. (2026) conducted an RCT in Atrial fibrillation (n=1,280). Abelacimab vs. Rivaroxaban daily was evaluated on Total major or clinically relevant non-major (CRNM) bleeding events (IRR 0.26, 95% CI 0.17-0.39, p=<0.001). Abelacimab reduced total major or clinically relevant non-major bleeding events by 74% compared with rivaroxaban in patients with AF (IRR 0.26; 95% CI 0.17-0.39; p<0.001).
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