A new anti-clotting medication called asundexian demonstrated significant potential in preventing recurrent strokes without increasing bleeding risks, according to preliminary findings presented at the American Stroke Association's International Stroke Conference 2026. The OCEANIC-STROKE study, a Phase III international trial involving over 12,300 stroke survivors, found that adding daily asundexian to standard antiplatelet therapy reduced the occurrence of ischemic stroke by 26% compared to placebo.
The research represents the first completed trial investigating whether Factor XI inhibitors like asundexian are better than standard therapy at safely preventing recurrent strokes. Asundexian works by inhibiting a clotting protein called Factor XI (FXIa), which is involved in producing large blood clots that can block blood vessels. Unlike other anticoagulants such as rivaroxaban and apixaban that inhibit Factor Xa, asundexian does not increase bleeding risk, according to the study findings.
"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 Dr. Mike Sharma, principal investigator of the study and professor of medicine at McMaster University. The American Stroke Association notes that nearly 1 in 4 stroke survivors will experience another stroke, making secondary prevention a critical medical priority.
The study included participants who had recently experienced mild to moderate ischemic stroke not caused by heart conditions, or transient ischemic attacks (TIAs) identified as high risk for progression to stroke. Participants were randomly selected to receive either standard antiplatelet therapy plus asundexian or standard therapy plus placebo, with neither patients nor researchers aware of treatment assignments during the trial. The reduction in stroke occurrence was consistent across all participants regardless of age, sex, stroke cause, or severity of the initial stroke.
Beyond reducing ischemic stroke occurrence, the medication also reduced disabling strokes and lowered cardiovascular death, stroke of any type, heart attack, and major bleeding events. Importantly, it did not increase bleeding within the brain or major bleeding, nor did it increase serious adverse effects. "Asundexian, when combined with standard antiplatelet therapy, helped reduce the chances of having another stroke without increasing the risk of bleeding," Sharma noted.
The implications of these findings are substantial for stroke prevention guidelines and clinical practice. Current American Stroke Association guidelines recommend antithrombotic therapy for nearly all stroke survivors, but dual antiplatelet therapy is limited to specific patient groups and not recommended for long-term use due to bleeding risks. "Antiplatelet therapy has limited effectiveness in preventing recurrent stroke because of bleeding risks," Sharma explained, noting that previous efforts to improve outcomes by adding other anti-clotting medications have failed due to increased bleeding risk or lack of benefit.
If approved by regulatory agencies like the U.S. Food and Drug Administration, which has granted asundexian fast-track designation for stroke prevention, the medication could become widely used for patients who have had non-cardioembolic stroke or TIA. The FDA's fast-track designation information is available at https://www.fda.gov. The study was conducted at 702 sites across 37 countries between January 2023 and February 2025, with participants followed for 3 to 31 months.
While the findings are promising, researchers note limitations including relatively few participants with severe strokes despite broad inclusion criteria. Additionally, analysis of brain imaging data collected in a substudy is not yet complete but may provide further information on asundexian's impact on clotting and bleeding. The study was funded by Bayer, which manufactures asundexian and provided both the medication and placebo used in the trial.
These preliminary findings could represent a significant advancement in stroke prevention, particularly for the substantial population of stroke survivors at risk of recurrence. With stroke now ranking as the fourth leading cause of death in the United States according to the American Heart Association's 2026 statistics available at https://www.heart.org, safer and more effective prevention strategies could have meaningful impact on public health outcomes and quality of life for stroke survivors worldwide.
