Bayer's Asundexian Reduces Ischemic Stroke Risk Without Raising Major Bleeding in Phase III Trial

Bayer reported topline results from the phase III OCEANIC-STROKE trial today showing that the investigational factor XIa inhibitor asundexian met its primary efficacy and safety endpoints in secondary stroke prevention. In study participants who had a non-cardioembolic ischemic stroke or a high-risk transient ischemic attack, asundexian 50 mg once daily added to antiplatelet therapy significantly reduced the risk of ischemic stroke compared with placebo given with antiplatelet therapy.1

Bleeding is a perennial concern when adding an anticoagulant to antiplatelet therapy. According to the company, investigators observed no increase in International Society on Thrombosis and Haemostasis major bleeding with asundexian compared with placebo.

Need for Secondary Prevention Options

OCEANIC-STROKE enrolled more than 12,300 participants globally and is the first completed phase III program for a factor XIa inhibitor. Investigators evaluated asundexian 50 mg once daily vs placebo in combination with antiplatelet therapy in a multicenter, randomized, placebo-controlled, double-blind, parallel-group, event-driven design. Investigators aimed to determine whether direct inhibition of factor XIa could lower the risk of thrombus formation and subsequent vessel blockage with minimal impact on hemostasis.

The need for new secondary prevention options remains high. Roughly 12 million people experience a stroke each year, and 20% to 30% of these events represent recurrences.2,3 In fact, research demonstrates that 1 in 5 stroke survivors have another stroke within 5 years.4 Moreover, recurrent ischemic strokes often result in greater disability and higher mortality than a first stroke.3,4

“As clinicians, we see every day how devastating a recurrent stroke can be for patients and their families. Even with currently available therapies, the risk of another stroke remains high, and each recurrence can have profound consequences," Mike Sharma, MD, principal investigator of the Population Health Research Institute (PHRI) OCEANIC-STROKE study, said in a statement. "The topline results from OCEANIC-STROKE indicate that asundexian may become a new treatment option to reduce this risk – representing a potential major step forward in secondary stroke prevention.”

FXIa plays distinct roles in coagulation, contributing modestly to normal hemostasis but more substantially to pathological thrombus formation and vessel occlusion. Inhibition of the enzyme may limit thrombus growth while preserving the formation of a hemostatic plug. Asundexian is a direct FXIa inhibitor designed to reduce thrombus formation that can lead to vessel stenosis or blockage without meaningfully affecting major bleeding risk. The investugational oral drug, if approved, will be dosed once-daily. Asundexian is currently not approved for use in any country, according to Bayer.

Asundexian History

The FDA granted asundexian Fast Track designation in May 2023 as a potential therapy for stroke prevention in adults with atrial fibrillation (AF).5 In November, Bayer announced it had halted the OCEANIC-AF phase 3 clinical trial for lack of efficacy in a head to head study of asundexian vs apixaban.6 At the time, the study’s Independent Data Monitoring Committee (IDMC) recommended that Bayer continue the phase 3 OCEANIC-STROKE trial, which launched in January 2023. 6

“We are excited by these positive topline findings which highlight the potential of factor XIa inhibition as a new way to help protect patients from a recurrent stroke," Christian Rommel, PhD, head of research and development at Bayer’s Pharmaceuticals Division, said in the statement. "This marks an important milestone in Bayer’s longstanding commitment to advancing innovation in thrombosis prevention."

The company indicated that it will engage regulatory authorities worldwide to prepare submissions for marketing authorization applications.

References

1. Bayer’s asundexian met primary efficacy and safety endpoints in Phase III OCEANIC-STROKE study in secondary stroke prevention. News release. Bayer. November 23, 2025. Accessed November 24, 2025. https://www.bayer.com/media/en-us/bayers-asundexian-met-primary-efficacy-and-safety-endpoints-in-landmark-phase-iii-oceanic-stroke-study-in-secondary-stroke-prevention/
2. Feigin VL, et al. World Stroke Organization (WSO): global stroke fact sheet 2022. Int J Stroke. 2022 Jan;17(1):18-29.
3. Feigin VL, et al. Pragmatic Solutions to Reduce Global Burden of Stroke. Lancet Neurol. 2023;22:1160–1206.
4. Kolmos M, et al. Recurrent ischemic stroke–a systematic review and meta-analysis. J Stroke Cerebrovasc Dis. 2021;30(8):105935.
5. Meglio M. Asundexian granted FDA Fast Track designation for stroke prevention in patients with AF. Patient Care Online. May 25, 2023. Accessed November 24, 2025. https://www.patientcareonline.com/view/asundexian-granted-fda-fast-track-designation-for-stroke-prevention-in-patients-with-af
6. Halsey G. Phase 3 trial of Factor XIa inhibitor asundexian halted for lack of efficacy. Patient Care Online. November 21, 2025. Accessed November 24, 2025. https://www.patientcareonline.com/view/phase-3-trial-of-factor-xia-inhibitor-asundexian-halted-for-lack-of-efficacy