Sunharbo (asundexian): FDA approval, pivotal trial and safety
Approved
Type
New molecular entity
FDA-approved use
To reduce the risk of stroke in adults following a recent mild-to-moderate non-cardioembolic ischemic stroke or a high-risk transient ischemic attackWording from FDA's list of novel approvals.
At a glance
Sunharbo (asundexian) is an oral factor XIa inhibitor approved to reduce the risk of stroke in adults after a recent mild-to-moderate non-cardioembolic ischemic stroke or a high-risk transient ischemic attack. In the phase 3 OCEANIC-STROKE trial, adding it to antiplatelet therapy lowered ischemic stroke versus placebo (6.2% vs. 8.4%; cause-specific hazard ratio 0.74; 95% CI 0.65 to 0.84). Major bleeding was similar between groups, and there is no boxed warning.
What it is and how it works
Asundexian inhibits activated factor XI, a clotting protein in the intrinsic coagulation pathway. Low factor XI levels have been linked to a lower risk of ischemic stroke. It is given on top of antiplatelet therapy. The aim is to reduce thrombosis without the added bleeding seen with broader anticoagulation.
Phase 3, double-blind, randomized, placebo-controlled trial. Patients were enrolled within 72 hours of stroke or TIA onset.
Patients
12,327 patients with a noncardioembolic ischemic stroke or high-risk TIA (6162 to asundexian, 6165 to placebo). Each had a nonlacunar infarct, a history of atherosclerosis, or atherosclerotic plaque on cerebrovascular imaging.
Compared with
Placebo, both added to planned single or dual antiplatelet therapy.
Primary endpoint
Ischemic stroke (efficacy); major bleeding was the primary safety outcome.
Result
Ischemic stroke occurred in 6.2% with asundexian vs. 8.4% with placebo (cause-specific hazard ratio 0.74; 95% CI 0.65 to 0.84; P<0.001).
Other results
The composite of cardiovascular death, myocardial infarction, or stroke was lower with asundexian than with placebo.
Safety in the trial
Major bleeding was 1.9% vs. 1.7% (hazard ratio 1.10; 95% CI 0.85 to 1.44). Adverse events were 69.3% vs. 70.1%; serious adverse events were 19.2% vs. 19.5%.
How does Sunharbo (asundexian) compare with the alternatives (Aspirin, Clopidogrel, Aspirin plus extended-release dipyridamole) for its approved use (to reduce the risk of stroke in adults following a recent mild-to-moderate non-cardioembolic ischemic stroke or a high-risk transient ischemic attack)? Summarize head-to-head and indirect evidence, efficacy, safety and where each fits, with citations.
Phase 3, international, double-blind, randomized trial, stopped early on the advice of the data monitoring committee.
Patients
14,810 high-risk patients with atrial fibrillation (mean age 73.9 years; 35.2% women; mean CHA2DS2-VASc 4.3).
Compared with
Standard-dose apixaban.
Primary endpoint
Stroke or systemic embolism (noninferiority); major bleeding was the primary safety objective.
Result
Asundexian was worse: stroke or systemic embolism in 98 patients (1.3%) vs. 26 (0.4%) with apixaban (hazard ratio 3.79; 95% CI 2.46 to 5.83).
Other results
Not reported in the source.
Safety in the trial
Major bleeding occurred in 17 patients (0.2%) with asundexian vs. 53 (0.7%) with apixaban (hazard ratio 0.32; 95% CI 0.18 to 0.55). Any adverse event appeared similar between groups.
There is no boxed warning. In OCEANIC-STROKE, major bleeding was similar to placebo (1.9% vs. 1.7%; hazard ratio 1.10; 95% CI 0.85 to 1.44), and overall adverse events were also similar (69.3% vs. 70.1%). Serious adverse events occurred in 19.2% and 19.5%, respectively. Bleeding remains the key clinical concern for any antithrombotic added to antiplatelet therapy. In the atrial fibrillation trial OCEANIC-AF, asundexian was worse than apixaban for stroke or systemic embolism (hazard ratio 3.79; 95% CI 2.46 to 5.83), though it caused less major bleeding. The label's use is not for cardioembolic stroke prevention.
What it competes with
After a non-cardioembolic ischemic stroke or high-risk TIA, secondary prevention relies on antiplatelet therapy, often dual therapy for a short period, plus statins and blood pressure and risk factor control.
AspirinStandard single antiplatelet agent for long-term secondary prevention.
ClopidogrelAntiplatelet used alone or with aspirin, with dual therapy usually limited to a short early period.
Aspirin plus extended-release dipyridamoleAlternative antiplatelet combination for long-term secondary prevention.
TicagrelorAntiplatelet used with aspirin for a short period after minor stroke or high-risk TIA in selected patients.
StatinsLipid-lowering therapy that is a core part of secondary prevention alongside antiplatelet treatment.
Bottom line for clinicians
Sunharbo is for patients with a recent mild-to-moderate non-cardioembolic ischemic stroke or high-risk TIA who are receiving antiplatelet therapy. Its benefit was shown as an add-on, with no clear excess of major bleeding in the trial. Clinicians should weigh individual bleeding risk and note that it was inferior to apixaban in atrial fibrillation, so it is not a substitute for anticoagulation there.
Dosing, contraindications and full warnings are in the prescribing information.
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Last updated November 10, 2026 by 2 Minute Medicine.
For healthcare professionals. A summary of public FDA documents and published trials, not medical advice. Check the full prescribing information before prescribing.
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