Asundexian: New Drug Reduces Stroke Recurrence Without Increasing Bleeding Risk

A neurologist calls the presentation of the Oceanic-Stroke study at the American Stroke Conference a “historic moment.” The international study evaluated asundexian, a new molecule that may prevent a second stroke without increasing the risk of bleeding – a common side effect of current therapies. Preventing stroke recurrence is a critical area of research, as stroke remains a leading cause of disability and death worldwide.

The study addresses a long-standing gap in vascular neurology: how to prevent stroke recurrence in patients who have experienced an ischemic stroke not caused by heart arrhythmias. Researchers explain that for decades, antiplatelet drugs like aspirin have been the standard treatment, but robust evidence of new, effective, and safe strategies to further reduce the risk of recurrence has been lacking.

Innovative Medication

Asundexian belongs to a novel class of oral anticoagulants that specifically target blood coagulation by inhibiting factor XIa. According to researchers, the goal is to block the formation of pathological thrombi responsible for stroke, without significantly interfering with normal coagulation, which protects against bleeding. This concept has been under investigation for years, but the recent completion of a large phase three study provides clear results.

Asundexian is an oral inhibitor of factor XIa (FXIa), administered once daily, for the secondary prevention of stroke. FXIa is a protein in the blood coagulation pathway involved in both thrombosis and hemostasis, but plays a more significant role in clot progression than in preventing bleeding.

Unlike traditional anticoagulants, which interfere with central stages of coagulation and substantially increase the risk of hemorrhage, FXIa is considered a promising target. Its inhibition is believed to reduce the formation of pathological thrombi with a more favorable safety profile.

Study Results

The Oceanic-Stroke trial, conducted between January 2023 and February 2025, included more than 12,000 patients across 37 countries, including Brazil. All participants had experienced an ischemic stroke not caused by heart issues or a high-risk transient ischemic attack (TIA) and were already receiving standard antiplatelet therapy.

The results indicated that asundexian reduced the risk of a new ischemic stroke by approximately 26% compared to placebo. “This difference emerged early, in the first few months, and persisted throughout the follow-up period,” noted Mike Sharma, MD, of McMaster University and the Population Health Research Institute in Hamilton, Canada. The study also showed a reduction in more severe strokes, those that cause significant disability or death.

Researchers emphasize the medication’s safety profile as a key finding. “Perhaps the most impressive data – which even drew applause during the presentation – was the safety data: there was no significant increase in bleeding, even brain hemorrhages, which has always been the biggest concern when considering anticoagulation after a stroke,” explained a neurologist.

The findings suggest, for the first time, that it may be possible to go beyond aspirin to further reduce the risk of recurrence of non-cardioembolic ischemic stroke without increasing the risk of bleeding. “This changes the game,” the neurologist concluded. “It’s not yet an option for immediate clinical use, but it paves the way for a new class of drugs in secondary stroke prevention – something that has been awaited for many years.”