BACKGROUND: Abelacimab is a fully human monoclonal antibody that binds to the inactive form of factor XI and blocks its activation. The safety of abelacimab as compared with a direct oral anticoagulant in patients with atrial fibrillation is unknown.
METHODS: Patients with atrial fibrillation and a moderate-to-high risk of stroke were randomly assigned, in a 1:1:1 ratio, to receive subcutaneous injection of abelacimab (150 mg or 90 mg once monthly) administered in a blinded fashion or oral rivaroxaban (20 mg once daily) administered in an open-label fashion. The primary end point was major or clinically relevant nonmajor bleeding.
RESULTS: A total of 1287 patients underwent randomization; the median age was 74 years, and 44% were women. At 3 months, the median reduction in free factor XI levels with abelacimab at a dose of 150 mg was 99% (interquartile range, 98 to 99) and with abelacimab at a dose of 90 mg was 97% (interquartile range, 51 to 99). The trial was stopped early on the recommendation of the independent data monitoring committee because of a greater-than-anticipated reduction in bleeding events with abelacimab. The incidence rate of major or clinically relevant nonmajor bleeding was 3.2 events per 100 person-years with 150-mg abelacimab and 2.6 events per 100 person-years with 90-mg abelacimab, as compared with 8.4 events per 100 person-years with rivaroxaban (hazard ratio for 150-mg abelacimab vs. rivaroxaban, 0.38 [95% confidence interval {CI}, 0.24 to 0.60]; hazard ratio for 90-mg abelacimab vs. rivaroxaban, 0.31 [95% CI, 0.19 to 0.51]; P<0.001 for both comparisons). The incidence and severity of adverse events appeared to be similar in the three groups.
CONCLUSIONS: Among patients with atrial fibrillation who were at moderate-to-high risk for stroke, treatment with abelacimab resulted in markedly lower levels of free factor XI and fewer bleeding events than treatment with rivaroxaban. (Funded by Anthos Therapeutics; AZALEA-TIMI 71 ClinicalTrials.gov number, NCT04755283.).
| Discipline Area | Score |
|---|---|
| Internal Medicine |  |
| Hemostasis and Thrombosis | |
| Cardiology | |
| Family Medicine (FM)/General Practice (GP) | |
| General Internal Medicine-Primary Care(US) | |
The bleeding is less with abelacimab, but it needs to show efficacy compared with rivaroxaban, which is being assessed in the ongoing phase 3 trial. Asundexian (another Factor XI inhibitor) also showed less bleeding in the phase 2 trial, but had increased strokes and systemic emboli in the phase 3 efficacy trial.
This trial showed lower bleeding risk, but efficacy must be properly studied and proven before this medication is ready for mainstream use.
Exciting results from a Phase 2b RCT that found monoclonal Ab inhibiting Factor XI led to less bleeding than rivaroxaban in patients with AFib.
Interesting result but I believe a subsequent study also revealed the new drug to be less efficacious than a DOAC.
