WHIPPANY, November 10, 2026 — The U.S. Food and Drug Administration has approved asundexian, marketed as Sunharbo, as the first Factor XIa inhibitor for secondary stroke prevention in adults following a non-cardioembolic ischemic stroke or high-risk transient ischemic attack (TIA).
How a New Class of Blood Thinner Works Differently
For decades, preventing a second stroke has involved a delicate balance. While antiplatelet drugs like aspirin are effective, adding traditional anticoagulants to boost protection often came at a high cost: a significantly increased risk of major bleeding. This new class of medication, Factor XIa inhibitors, appears to break that trade-off.
Asundexian works by selectively inhibiting a protein in the blood clotting cascade called activated Factor XI. According to clinical investigators, this protein plays a minor role in forming the initial clot that seals a minor vessel injury—a process known as hemostasis. However, it plays a major role in amplifying the generation of thrombin, which drives the growth of larger, pathological clots that can cause a stroke. Pre-clinical data suggest that by targeting Factor XIa, the drug can interfere with the formation of these harmful clots while largely leaving the body’s ability to stop bleeding at the site of an injury intact.
Clinical Trial Results: Efficacy and Safety in Numbers
The FDA’s decision was based on the large-scale phase 3 OCEANIC-STROKE trial, which enrolled over 12,000 patients across 702 centers in 37 countries. All participants had experienced a mild to moderate non-cardioembolic ischemic stroke or a high-risk TIA and were receiving standard antiplatelet therapy. Within 72 hours of their event, they were randomly assigned to receive either a 50 mg once-daily tablet of asundexian or a placebo.
The results showed a clear benefit in reducing the risk of another ischemic stroke. The incidence of ischemic stroke was 6.2% in the asundexian group compared to 8.4% in the placebo group. This represents a 26% reduction in the risk of recurrent stroke, with a hazard ratio of 0.74.
The encouraging part of the findings was the safety profile. Major bleeding rates, a primary safety endpoint, were virtually unchanged between the two groups. The rate of ISTH major bleeding was 1.9% with asundexian and 1.7% with placebo. The most common adverse reaction reported was diarrhea.
What This Means for Patients and Next Steps
These findings suggest that asundexian offers a new option for patients at high risk of a recurrent stroke who are also at significant risk for bleeding complications. It is not approved for stroke prevention in patients with atrial fibrillation, and it should be withheld for 24 hours before and after surgery or thrombolysis.
As with any new treatment, patients should talk to their doctor to determine if asundexian is an appropriate option for them. The FDA granted the drug Fast Track and Priority Review designations earlier in 2026, reflecting the significant unmet need for safer anticoagulation in this patient population. The next scheduled date for Bayer’s financial reporting is February 24, 2027.
Sources
- FDA Approves Factor XIa Inhibitor Asundexian for Secondary Stroke Prevention | NeurologyLive – Clinical Neurology News and Neurology Expert Insights
- Asundexian Receives FDA Approval for Secondary Stroke Prevention | HCPLive
- Bayer’s SUNHARBO® (asundexian), 50 mg tablets, the First and Only Factor XIa Inhibitor, Approved by the U.S. FDA to Reduce the Risk of Stroke in Adults With Recent Non-Cardioembolic Ischemic Stroke or High-Risk Transient Ischemic Attack… – AOL
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