FDA approves Bayer’s asundexian to cut ischemic stroke risk by 26%
Key Facts
The U.S. Food and Drug Administration on November 9, 2026, approved Sunharbo tablets, each containing 50 mg of asundexian, to reduce stroke risk in specific groups after a mild to moderate non-cardioembolic ischemic stroke or high-risk transient ischemic attack. The FDA said the drug is the first factor XIa inhibitor to receive its approval. It is used alongside antiplatelet therapy, according to the agency’s statement. The decision grants U.S. authorization to a drug tested for its effectiveness in preventing recurrent stroke in these groups. The authorization does not cover stroke prevention in people with atrial fibrillation.
The approval was based on results from the Phase III OCEANIC-STROKE study, which included 12,327 adults. Researchers randomly assigned participants to receive asundexian or a placebo within 72 hours of symptom onset. Participants in both groups received antiplatelet treatment alongside their assigned study treatment. This comparison made it possible to assess the effect of adding the drug to antiplatelet therapy in preventing ischemic stroke. The FDA limited the authorization to specific groups of patients after stroke or high-risk transient ischemic attack.
Asundexian at a dose of 50 mg once daily reduced the risk of ischemic stroke by 26% compared with placebo over a median treatment period of 14.2 months, according to the FDA. This figure measures the outcome against the placebo group over the stated treatment follow-up period. In results published by Bayer on February 5, 2026, the rate of major bleeding under the ISTH definition was about 1.9% with asundexian, compared with 1.7% with placebo. The company reported a hazard ratio of 1.10, with a 95% confidence interval of 0.85 to 1.44. Bayer said the results showed no increase in the rate of major bleeding under that definition.
The FDA said the overall rate of major bleeding was similar among Sunharbo users and the placebo group, but noted a higher rate among users over 75 and during the first 90 days of treatment. Diarrhea was the most common adverse reaction among those reported in 3% or more of users. These results add a safety dimension to the reduction in stroke risk recorded in the study, with a particular signal related to age and the start of treatment. The FDA did not specify separate bleeding rates for these two groups in its statement. These signals remain part of the drug information cited by the agency when it announced the approval.
The FDA’s precautions include a recommendation against using the drug with strong P-gp and CYP3A4 inducers, and against its use in moderate or severe hepatic impairment. The drug is not approved to prevent stroke in patients with atrial fibrillation. The agency also said it is not recommended with drugs that induce both P-gp and CYP3A4, such as carbamazepine. Sunharbo should be stopped at least 24 hours before elective surgery or interventional procedures, and for at least 24 hours after thrombolysis to treat acute stroke. These restrictions define the conditions of use accompanying the U.S. authorization.
The U.S. approval followed two regulatory reviews under which the FDA granted the drug Fast Track and Priority Review designations. On November 23, 2025, Bayer said OCEANIC-STROKE had met its primary efficacy and safety endpoints and that it would engage with health authorities worldwide in preparation for regulatory submissions. Earlier, on November 19, 2023, an independent monitoring committee recommended stopping the OCEANIC-AF study after its monitoring showed lower efficacy for asundexian than apixaban in patients with atrial fibrillation, while recommending that OCEANIC-STROKE continue. The decision to stop the study concerned patients with atrial fibrillation, while the current approval focuses on specific groups after non-cardioembolic stroke or high-risk transient ischemic attack. On November 3, 2026, Bayer had said the drug remained under review by the FDA, the European Medicines Agency and Japan’s Ministry of Health, Labour and Welfare; the U.S. approval was then announced on November 9.