An investigational anti-clotting medication called asundexian demonstrated a reduction in the risk of a second ischemic stroke without raising bleeding concerns, 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, represents the first completed trial of a Factor XI inhibitor investigating whether this new class of medication can safely prevent recurrent strokes better than standard therapy.
This development is significant because nearly one in four stroke survivors will experience another stroke, according to the American Stroke Association. Current prevention strategies have limitations: standard antiplatelet therapy like aspirin has limited effectiveness due to bleeding risks, while dual antiplatelet therapy combining medications is not recommended for long-term use. Previous attempts to add other blood-thinning medications have failed due to increased bleeding risk, lack of benefit, or both.
Asundexian works differently from existing anticoagulants by inhibiting a clotting protein called Factor XI. People born with a genetic deficiency of this protein are known to have lower stroke risk without spontaneous bleeding issues. In the trial, participants who had recently experienced a mild to moderate ischemic stroke or high-risk transient ischemic attack received either standard antiplatelet therapy plus daily asundexian or standard therapy plus a placebo.
The results showed that adding asundexian reduced the occurrence of ischemic stroke by 26% compared to placebo, with consistent benefits across all participant groups regardless of age, sex, stroke cause, or initial stroke severity. Importantly, the medication did not increase bleeding within the brain or major bleeding events and did not increase serious adverse effects. The treatment also lowered the combined risk of cardiovascular death, stroke of any type, heart attack, and major bleeding.
"Asundexian holds the potential to reduce the risk of a recurrent stroke over the long term without an increased safety risk," said Dr. Mike Sharma, principal investigator of the study and professor at McMaster University. "This is a major advance in our ability to prevent strokes in people at risk of stroke recurrence." The American Stroke Association provides stroke prevention guidelines and information at https://www.stroke.org.
If approved by regulatory agencies like the U.S. Food and Drug Administration, which has granted asundexian fast-track designation for stroke prevention, this medication could become widely used for patients who have had non-cardioembolic strokes or TIAs. The study was conducted at 702 sites in 37 countries between January 2023 and February 2025, with participants followed for 3 to 31 months. Bayer, which manufactures asundexian, funded the study and provided the medication and placebo.
It is important to note that these findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal. The research was presented as an abstract at the American Stroke Association conference, and abstracts presented at such meetings are not peer-reviewed. The American Heart Association's financial information is available at https://www.heart.org/en/about-us/aha-financial-information.
The implications of this research are substantial for stroke survivors worldwide. Stroke remains a leading cause of death and disability, and preventing recurrent strokes is crucial for improving long-term outcomes. The potential availability of a medication that reduces stroke recurrence without increasing bleeding risk could transform secondary stroke prevention strategies and improve quality of life for millions of stroke survivors globally.
