In a trial, recurrent strokes occurred in 6.2% of patients given Sunharbo and 8.4% given a placebo, a 26% relative reduction. The approval gives eligible patients a daily treatment option.
The US Food and Drug Administration approved Bayer’s Sunharbo on 9 November 2026 to reduce the risk of another stroke. The once-daily medicine is approved for people whose previous stroke was not caused by a clot from the heart and for those who have had a high-risk transient ischemic attack, often called a mini-stroke.
Many blood thinners are not used to prevent repeat strokes in this setting because they increase bleeding risk, STAT said. Sunharbo’s active ingredient, asundexian, blocks Factor XIa, a protein involved in clotting. The approach aims to prevent harmful clots without increasing bleeding, though that is not a guarantee of safety.
The Phase 3 OCEANIC-STROKE trial randomly assigned 12,327 patients to asundexian or a placebo within 72 hours of a noncardioembolic ischemic stroke or high-risk mini-stroke. Neither patients nor researchers knew who received which treatment. Participants received 50 mg of asundexian daily or a placebo alongside one or two planned antiplatelet medicines, which help prevent clots. The median follow-up was 567 days. These details describe the regimen studied in the trial.
STAT said 53 patients would need treatment for one year to prevent one recurrent stroke.
The American College of Cardiology’s summary of the trial showed similar major bleeding rates in the two groups, with a cause-specific hazard ratio of 1.10 and a 95% confidence interval of 0.85–1.44. The uncertainty around the comparison allowed for either a lower or a higher bleeding risk with asundexian.
| Outcome | Asundexian | Placebo |
|---|---|---|
| Major bleeding | 1.9% | 1.7% |
| Adverse events | ||
Another 27 sites recorded high pollution, while Hillingdon’s fine-particle reading reached 129 micrograms per cubic meter. London’s mayor issued a high-pollution alert for 10 November.
China’s drug regulator approved Sunharbo in late October 2026, before the US decision. The medicine is the first approved treatment designed to prevent harmful clots by blocking Factor XIa.
In an editorial accompanying the trial results, physician Marion Boulanger called asundexian a very promising option for secondary prevention after noncardioembolic ischemic stroke or transient ischemic attack, but said studies of Factor XI inhibitors with longer follow-up, such as five or ten years, were needed to determine whether their overall clinical benefit persists.
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