The investigational anti-clotting medication asundexian (Bayer) has demonstrated a reduction in the risk of a second ischaemic stroke without raising bleeding-related concerns, according to preliminary late-breaking results from the OCEANIC-STROKE trial presented today at the International Stroke Conference (ISC; 4–6 February 2026, New Orleans, USA).
“Asundexian holds the potential to reduce the risk of a recurrent stroke over the long term without an increased safety risk,” said Mike Sharma (McMaster University, Hamilton, Canada), who is the co-principal investigator for OCEANIC-STROKE alongside his McMaster University colleague Ashkan Shoamanesh. “This is a major advance in our ability to prevent strokes in people at risk of stroke recurrence.”
A 2021 guideline from the American Stroke Association (ASA) states that antithrombotic therapy—including antiplatelet or anticoagulant agents—is recommended for the prevention of secondary stroke in nearly all stroke survivors, while dual antiplatelet therapy (DAPT) is typically only advised in very specific cases, including patients with early-arriving minor stroke and high-risk transient ischaemic attack or severe symptomatic intracranial stenosis. DAPT involves giving a second medication like clopidogrel or dipyridamole in addition to aspirin, and is not recommended for long-term use.
“Antiplatelet therapy has limited effectiveness in preventing recurrent stroke because of bleeding risks,” Sharma continued. “Previous efforts to improve outcomes by adding other anticlotting or blood-thinning medications have not succeeded due to the increased risk of bleeding, lack of benefit, or both.”
Asundexian is an oral medication that inhibits the clotting protein Factor XIa (FXIa), which is involved in the production of large clots that can block blood vessels. Other anticoagulants—such as rivaroxaban and apixaban—inhibit a different clotting protein called Factor Xa to reduce stroke risks. However, unlike these medications, asundexian does not increase the likelihood of bleeding.
The international, phase-three OCEANIC-STROKE trial, which enrolled 12,327 adult stroke survivors (average age, 68 years; 67% male) at 702 sites spanning 37 countries, is investigating whether adding daily asundexian to antiplatelet therapy could reduce the chances of a new stroke caused by a blood clot without increasing the risk of bleeding or other adverse events. Participants had to have recently had a mild-to-moderate ischaemic stroke that was not caused by a heart condition like cardiac arrhythmia or a transient ischaemic attack (TIA) deemed as having a high risk of progressing to a stroke within one week. Some 43% of the participants had a stroke assumed to be caused by plaque buildup in the large arteries leading to the brain, while 30% had a stroke of undetermined cause.
In the trial, patients were randomly selected to receive either standard antiplatelet therapy—aspirin only or DAPT—plus a daily 50mg dose of asundexian, or standard antiplatelet therapy plus a placebo. Both the participants and the researchers were blinded regarding which group patients were randomised to during the trial. Participants were followed up for between three and 31 months to monitor occurrences of ischaemic stroke or major bleeding as well as significant cardiovascular events.
OCEANIC-STROKE findings
The OCEANIC-STROKE researchers ultimately found that, compared to a placebo, adding asundexian to antiplatelet medication reduced the occurrence of ischaemic stroke by 26%—and this reduction was consistent for all participants regardless of several key factors, including age or sex, cause of stroke, or the severity of the first stroke.
Patients who received asundexian also experienced a reduced occurrence of disabling stroke, but with no increase in bleeding within the brain or major bleeding, nor any uptick in the occurrence of serious adverse events, as compared to patients in the placebo group.
A lower frequency of cardiovascular death, stroke of any type, heart attack and major bleeding was seen with asundexian versus placebo too, which the investigators believe indicates an overall benefit in patients who receive the drug.
“Asundexian—when combined with standard antiplatelet therapy—helped reduce the chances of having another stroke without increasing the risk of bleeding,” Sharma explained. “This benefit applies to all types of strokes, not just those caused by plaque buildup in large arteries. If approved by the FDA [Food and Drug Administration], asundexian could be widely used for patients who have had a non-cardioembolic stroke or a TIA.”
“The consistent reduction in secondary events with asundexian across all types of strokes included in the trial is particularly striking,” added Shoamanesh. “OCEANIC-STROKE was deliberately designed with the goal of making the findings generalisable to the many ways stroke presents in clinical practice. These results provide confidence that, if approved, asundexian could become an important option for secondary stroke prevention across a broad range of stroke patients.”
A key limitation acknowledged by the OCEANIC-STROKE investigators is its inclusion of “relatively few” participants with severe strokes—despite the study having broad inclusion criteria that could hypothetically have included more of these patients.
Looking to the future, the investigators also highlight a substudy of OCEANIC-STROKE through which brain imaging and standardised magnetic resonance imaging (MRI) scans were collected for participants. While analyses of these data are not yet complete, the eventual results should provide further information on the impact of asundexian on both clotting and bleeding.
“Modern secondary stroke prevention should be what I call ‘more than just aspirin’. Patients with multiple risk factors and non-cardioembolic stroke are not risk-free of another stroke, even if they take aspirin,” said Andrei Alexandrov (Banner Health, Phoenix, USA), speaking to NeuroNews to discuss these new data. “FXIa inhibitors offer extra risk reduction and will be a welcome addition to our options for secondary prevention.”
Bayer—the company that manufactures asundexian—funded OCEANIC-STROKE, and provided the investigational medication and placebo used in the trial. Asundexian is yet to gain regulatory approval in any country, but received US FDA fast-track designations for secondary stroke prevention in non-cardioembolic ischaemic stroke patients in 2022 and prevention of stroke and systemic embolism in atrial fibrillation (AF) patients in 2023.
