Asundexian Reduces Stroke Risk Across Subtypes in OCEANIC-STROKE Trial | ISC 2026

Asundexian Shines in the OCEANIC‑STROKE Trial: A New Hope for Secondary Stroke Prevention

In a prespecified secondary analysis of the phase 3 OCEANIC‑STROKE trial (NCT05686070), the factor XIa (FXIa) inhibitor asundexian cut the risk of recurrent ischemic stroke across all major non‑cardioembolic subtypes without raising major bleeding rates. The findings were unveiled as a late‑breaking abstract at the International Stroke Conference 2026 in New Orleans.

Why Factor XIa Matters

Genetic deficiency of FXI has been linked to fewer ischemic strokes while sparing patients from intracerebral hemorrhage. Asundexian is a once‑daily oral drug that selectively blocks FXIa, aiming to prevent clot formation without compromising normal haemostasis.

Trial Design at a Glance

• 12,327 participants with recent non‑cardioembolic ischemic stroke (NIHSS ≤ 15) or high‑risk TIA (ABCD² ≥ 6).
• Randomised within 72 hours to asundexian 50 mg once daily or placebo, on top of standard antiplatelet therapy.
• Follow‑up up to 31 months.
• Stroke subtypes classified by TOAST criteria.

Primary Outcome: A 26% Hazard Reduction

Lead author Mike Sharma reported that asundexian lowered the primary efficacy end point—time to first ischemic stroke—by 26% compared with placebo, with no excess major bleeding or intracranial haemorrhage.² This result mirrors the headline figure in the AJMC article and Bayer’s own press release.⁴

Subtype Analysis: Consistency Across Etiologies

Among the 11,676 participants with a qualifying ischemic stroke, three subgroups emerged:

“We saw clear reductions in ischemic stroke irrespective of qualifying subtype,” said lead author Ashkan Shoamanesh. Hazard ratios ranged from 0.61 to 0.82, and statistical interaction tests were non‑significant, indicating a uniform treatment effect.¹

Safety Profile Holds Up

Across all subgroups, the main safety end point—major bleeding defined by ISTH criteria—did not increase. Symptomatic intracranial haemorrhage and haemorrhagic stroke were numerically lower with asundexian, even among patients with small‑vessel disease who are traditionally at higher bleeding risk.

ESUS: A Challenging Frontier

In the embolic stroke of undetermined source (ESUS) cohort, asundexian achieved a 47% relative reduction in recurrent ischemic stroke, although the result did not reach statistical significance. Importantly, no excess bleeding was observed, suggesting a favourable risk‑benefit balance for this hard‑to‑treat group.

What In other words for Future Stroke Care

The consistent efficacy and safety across stroke mechanisms support the concept that FXIa inhibition could grow a “second line” antithrombotic strategy for patients who have already received antiplatelet therapy. If regulatory approval follows, clinicians may soon have an oral option that intensifies protection without the bleeding trade‑off that limits many current anticoagulants.

Frequently Asked Questions

What is asundexian?

Asundexian is an investigational oral inhibitor of factor XIa, developed by Bayer to prevent clot‑driven events such as ischemic stroke.

How does it differ from traditional anticoagulants?

Traditional anticoagulants (e.g., warfarin, direct‑acting oral anticoagulants) target thrombin or factor Xa and are associated with higher bleeding rates. Asundexian selectively blocks FXIa, aiming to curb thrombosis while preserving normal haemostasis.

What were the main results of the OCEANIC‑STROKE trial?

The trial showed a 26% reduction in the hazard of first recurrent ischemic stroke and no increase in major bleeding when asundexian was added to standard antiplatelet therapy.

Is asundexian safe for patients with small‑vessel disease?

Yes. The subgroup analysis reported no rise in major bleeding or haemorrhagic stroke, and numerically fewer haemorrhagic strokes were observed in the small‑vessel cohort.

When might asundexian become available?

The trial has met its primary efficacy and safety endpoints, but regulatory approval will depend on further review by health authorities.

Next Steps for Clinicians and Researchers

While the data are encouraging, real‑world implementation will require:

• Guideline updates that incorporate FXIa inhibition for secondary stroke prevention.
• Post‑marketing surveillance to confirm long‑term safety.
• Education on patient selection, especially for ESUS and large‑artery atherosclerosis cases.

Stay tuned for upcoming presentations at major neurology meetings and potential regulatory filings from Bayer.