FDA clears Bayer's asundexian as first FXIa inhibitor for secondary stroke prevention

The FDA handed Bayer's asundexian its approval on November 9, 2026, clearing the once-daily pill for use alongside antiplatelet therapy in adults recovering from a recent mild to moderate non-cardioembolic ischemic stroke or a high-risk transient ischemic attack. Regulators called it the first factor XIa inhibitor approved in the US for that purpose, following Fast Track and Priority Review designations earlier in the year. The label stops short of atrial fibrillation: asundexian is not approved for stroke prevention in those patients.

The decision rides on OCEANIC-STROKE, a double-blind, placebo-controlled trial run at 702 centers across 37 countries. Investigators randomized 12,327 adults within 72 hours of symptom onset, giving 6,162 of them asundexian 50 mg daily and 6,165 a placebo, all on planned single or dual antiplatelet therapy. Ischemic stroke hit 6.2% of the asundexian arm versus 8.4% on placebo, a cause-specific hazard ratio of 0.74 that the FDA framed as a 26% risk reduction over a median 14.2 months of treatment.

Bleeding was the question everyone was watching, and the numbers came back close: ISTH major bleeding landed at 1.9% with asundexian against 1.7% on placebo. Overall adverse events (69.3% vs 70.1%) and serious adverse events (19.2% vs 19.5%) tracked similarly, with diarrhea the most common reaction at 3% or more. The FDA still flagged subgroup signals — more major bleeding in patients over 75 and during the first 90 days, plus more gastrointestinal bleeding than placebo.

The trial's key secondary composite of cardiovascular death, myocardial infarction or stroke also favored asundexian. But ischemic stroke within the first 90 days showed no significant difference (3.0% vs 3.5%; csHR, 0.84; P = .08), which shut down formal hierarchical testing of lower-ranked secondary endpoints. Investigators noted that earlier attempts to stack anticoagulation on top of antiplatelets for long-term secondary prevention had flopped on weak efficacy, excess bleeding, or both.

"Stroke is a leading cause of disability and death in the United States, and survivors are at risk of having another stroke," said Hylton Joffe, MD, MMSc, director of the FDA's Office of Cardiology, Hematology, Endocrinology, and Nephrology. "Today's approval represents a meaningful advance for patients and health care providers seeking a new option for secondary stroke prevention."

The label comes with guardrails. Asundexian shouldn't be coadministered with drugs that are both P-glycoprotein inducers and strong CYP3A4 inducers, such as carbamazepine, because they may blunt efficacy, and it isn't recommended for patients with moderate or severe hepatic impairment. Clinicians should hold the drug at least 24 hours before elective surgery or invasive procedures, and at least 24 hours after thrombolysis for acute ischemic stroke.