FDA approves Sunharbo to lower the risk of another stroke after a mild-to-moderate stroke or mini-stroke

The Food and Drug Administration on November 9 approved Sunharbo (asundexian), a once-daily 50 mg tablet from Bayer, to lower the chance of a second stroke in some adults. It is cleared for use alongside antiplatelet therapy in people who have recently had a mild-to-moderate ischemic stroke caused by a clot that did not form in the heart, or a high-risk transient ischemic attack, often called a mini-stroke.

The FDA's announcement calls Sunharbo the first factor XIa (FXIa) inhibitor. "Stroke is a leading cause of disability and death in the United States, and survivors are at risk of having another stroke," said Hylton V. Joffe, director of the FDA's Office of Cardiology, Hematology, Endocrinology, and Nephrology.

CDC figures show the scale. Each year, more than 795,000 people in the U.S. have a stroke, and about 185,000 of those strokes, close to a quarter, happen to people who have already had one, according to the Centers for Disease Control and Prevention. About 87% of strokes are ischemic, meaning blood flow to the brain is blocked, the CDC says.

What the trial showed

The approval rests on a phase 3 trial called OCEANIC-STROKE, which enrolled 12,327 adults. Patients were randomly assigned to asundexian or a placebo within 72 hours of their symptoms starting, and everyone also received antiplatelet therapy. Neither patients nor doctors knew who was getting which. Over a median of 14.2 months of treatment, the drug cut the risk of ischemic stroke by 26% relative to placebo, the FDA says.

That 26% is a relative reduction. The FDA's announcement does not say how many patients in each group went on to have a stroke, so it does not show how many strokes the drug would prevent among a given number of patients. The trial's registry entry, sponsored by Bayer, listed the study as completed in October 2025 and showed no posted results when read on November 10, 2026.

Bleeding risk and other limits

The FDA's announcement singles out bleeding. Major bleeding occurred at a similar rate overall in the two groups, but it was higher on Sunharbo among patients over 75 and in the first 90 days on the drug. Bleeding in the digestive tract was more common with the drug than with placebo.

The agency also lists situations to avoid. Sunharbo is not recommended for people with moderate or severe liver impairment, or with medicines that are both P-gp and strong CYP3A4 inducers, such as carbamazepine, because they may make it less effective. Patients should not take it for at least 24 hours before planned surgery or an invasive procedure, or for at least 24 hours after thrombolysis, the clot-dissolving treatment for an acute ischemic stroke.

It is not approved to prevent stroke in people with atrial fibrillation, an irregular and often rapid heartbeat. Bayer tested asundexian in that group too, against apixaban, in a trial of 14,830 people called OCEANIC-AF. Its registry record shows the study was stopped on the recommendation of its independent data monitoring committee, with its primary completion date listed as January 31, 2024.

What comes next

The FDA gave the application Fast Track status, which it uses to speed the development and review of drugs for serious conditions with an unmet need, and Priority Review, which sets a goal of acting on an application within 6 months instead of 10. It granted the approval to Bayer HealthCare Pharmaceuticals of Whippany, New Jersey. Whether the drug suits a particular patient, given their age, other medicines and bleeding risk, is a question for the doctor treating them. The FDA answers consumer questions at 1-888-INFO-FDA (1-888-463-6332).