Stroke remains a leading cause of death and disability worldwide. Each year, approximately 12 million people experience a new stroke, and acute ischemic stroke (AIS) accounts for nearly 87 percent of all cases. Of those who survive a first stroke or high-risk transient ischemic attack (TIA), five to 16 percent will have a recurrent stroke within the first year, and up to 26 percent will experience a secondary stroke within five years. Recurrent strokes are often more severe, carry twice the risk of mortality, and are associated with poorer functional outcomes compared with first-ever strokes. For patients and families, this translates into increased disability, long-term cognitive decline, and a heavier healthcare burden.
To prevent another stroke, doctors often prescribe antiplatelet drugs, like aspirin, clopidogrel, or dipyridamole. These medications reduce the ability of platelets to stick together and form clots, lowering the risk of a blocked artery in the brain. In some high-risk patients, clinicians may use short-term dual-antiplatelet therapy (DAPT) — combining aspirin with clopidogrel or ticagrelor.
However, while these therapies help, they are far from perfect. Aspirin lowers the risk of recurrent stroke by roughly 22 percent, but many patients still have another stroke. More intensive therapies can offer extra protection in certain cases, but often increase the risk of serious bleeding, which limits long-term use. Older adults and patients with conditions such as atrial fibrillation or kidney and liver disease are particularly vulnerable, making it difficult to find treatments that balance safety and effectiveness.
Against this backdrop, new data unveiled today at the American Heart Association’s International Stroke Conference are drawing attention. Bayer announced Phase 3 results from the OCEANIC-STROKE trial, showing that its investigational drug asundexian significantly reduced the risk of recurrent ischemic stroke without increasing major bleeding.
Changing stroke prevention
Bleeding remains one of the biggest challenges in stroke prevention. Many patients have factors that make them prone to bleeding, including cancer, brain vessel conditions like cerebral amyloid angiopathy, older age, or organ dysfunction. Certain medications or procedures, such as multiple blood thinners after heart procedures, further increase the risk.
“After a stroke, the early period is a fragile time. The risk for bleeding, particularly in the brain, is at its highest, which makes it difficult to balance clot prevention with safety. Finding that balance has been a major challenge for the clinical community,” Sara Hegab, Head of Specialty and Pipeline, US Medical Affairs at Bayer, told DDN.
Clinicians must walk a fine line between lowering doses to reduce bleeding and increasing the chance of another stroke. A therapy that protects against recurrent strokes without increasing serious bleeding would offer a long-sought solution, allowing doctors to treat high-risk patients with greater confidence and fewer compromises.
Asundexian works alongside standard anti-platelet therapies by targeting factor XIa (FXIa), a protein involved in pathological clot formation. Unlike traditional anticoagulants, which interfere with the main clotting pathway and increase bleeding risk, FXIa inhibitors selectively prevent dangerous clots without affecting normal blood clotting. This makes the drug particularly promising for patients who are at high risk of bleeding but still need protection against recurrent strokes.
“Imagine cutting yourself in the kitchen. Your body needs to form a clot to stop bleeding — that’s healthy hemostasis. factor XIa doesn’t play a big role there, which is why asundexian can target pathological clotting while preserving normal clotting,” said Hegab.
What does this mean for patients?
OCEANIC-STROKE was a large, international trial of over 12,300 patients. Patients received once-daily asundexian 50mg alongside standard antiplatelet therapy. The drug reduced recurrent ischemic stroke by 26 percent compared with placebo (6.2 percent versus 8.4 percent with placebo), with similar reductions observed across all stroke types. The benefit was consistent across age, sex, stroke subtype, severity, and concomitant therapies. Rates of major bleeding were comparable to placebo, as were minor bleeding events and other safety outcomes.
“The trial included all non-cardioembolic stroke subtypes, with demographics representative of the US and global population. That means these results are broadly applicable,” noted Hegab.
Even with antiplatelet therapy, one in 10 patients still have a recurrent stroke in the first year. Asundexian’s trial showed it could reduce that further without increasing bleeding, a major limitation of other anticoagulants.
If approved, asundexian could give patients a safer, more effective option for long-term secondary stroke prevention, especially those who cannot tolerate prolonged dual therapy or traditional anticoagulants. As the first FXIa inhibitor to show both efficacy and safety in secondary stroke prevention, asundexian may reshape how clinicians approach the prevention of recurrent strokes, offering hope for millions of patients worldwide.
