An investigational anti-clotting medication, asundexian, has shown promise in reducing the risk of a second clot-caused stroke without raising bleeding concerns, according to preliminary findings presented at the American Stroke Association’s International Stroke Conference 2026. The research, known as the OCEANIC-STROKE trial, is the first completed study of a Factor XI inhibitor investigating its potential to safely prevent recurrent strokes.
Stroke remains a leading cause of death and disability worldwide, with nearly 1 in 4 stroke survivors experiencing another stroke. Current antiplatelet therapies, such as aspirin, are limited by bleeding risks. Asundexian targets Factor XIa, a clotting protein involved in forming large blood clots, without increasing bleeding—a significant advantage over existing anticoagulants like rivaroxaban and apixaban, which inhibit Factor Xa and carry bleeding risks.
The trial enrolled 12,327 adults (average age 68; 67% male) from 702 sites across 37 countries. Participants had recently experienced a mild-to-moderate ischemic stroke or a high-risk transient ischemic attack (TIA) not caused by heart conditions like atrial fibrillation. They were randomly assigned to receive either standard antiplatelet therapy plus a daily 50 mg dose of asundexian or standard therapy plus a placebo. Neither patients nor researchers knew the treatment assignments.
Over a follow-up period of 3 to 31 months, researchers found that adding asundexian reduced the occurrence of ischemic stroke by 26% compared to placebo. This benefit was consistent across age, sex, stroke cause, and severity. Additionally, asundexian reduced the occurrence of disabling strokes and did not increase bleeding within the brain, major bleeding, or other serious adverse events. The medication also lowered the composite outcome of cardiovascular death, stroke, heart attack, and major bleeding, indicating an overall patient benefit.
“Asundexian holds the potential to reduce the risk of a recurrent stroke over the long term without an increased safety risk. This is a major advance in our ability to prevent strokes in people at risk of stroke recurrence,” said principal investigator Dr. Mike Sharma, professor of medicine at McMaster University and senior scientist at the Population Health Research Institute.
The study is limited by relatively few participants with severe strokes, despite broad inclusion criteria. A substudy analyzing brain imaging data is ongoing and may provide further insights. Asundexian is not yet approved by any regulatory agency, but the U.S. Food and Drug Administration has granted it fast-track designation for stroke prevention after non-cardioembolic ischemic stroke. Bayer, which manufactures asundexian, funded the study.
These findings, if confirmed in peer-reviewed publication, could change clinical practice by offering a safer, more effective option for secondary stroke prevention. The American Stroke Association’s guidelines currently recommend antiplatelet therapy for most stroke survivors, but dual antiplatelet therapy is limited to specific cases due to bleeding risk. Asundexian may provide a new tool for long-term prevention in a broader patient population.
