A stroke can change a person’s life in an instant, and for many survivors, the fear of having another stroke never fully goes away. Doctors know that once someone has had a stroke, the risk of a second one is much higher.
In fact, nearly one in four stroke survivors will experience another stroke at some point. Preventing this second event is one of the biggest challenges in stroke care today.
Most strokes are caused by blood clots blocking blood flow to the brain. To lower the risk of another stroke, patients are usually given medicines that reduce clot formation, such as aspirin or other antiplatelet drugs. These medicines help stop blood cells from sticking together. However, they are not perfect.
While they reduce clotting, they also raise the risk of bleeding, especially if stronger combinations are used for a long time. Because of this, doctors have limited options when trying to better protect patients from another stroke.
Now, a large international study has brought new hope. Researchers have found that an experimental drug called asundexian may reduce the risk of a second stroke without increasing dangerous bleeding.
The findings were presented at the American Stroke Association’s International Stroke Conference in 2026 and have attracted strong interest from doctors and researchers around the world.
Asundexian works differently from current blood-thinning medicines. Instead of blocking clotting broadly, it targets a specific protein in the blood called Factor XI. This protein plays a role in forming large clots that can block blood vessels.
Scientists have known for years that people who are born with very low levels of Factor XI tend to have fewer clot-related strokes and rarely suffer from serious bleeding. This made Factor XI an attractive target for new treatments.
The study, called OCEANIC-STROKE, included more than 12,300 people who had recently experienced a mild to moderate stroke caused by a blood clot.
Some participants had a transient ischemic attack, often called a mini-stroke, where symptoms disappear quickly but the risk of a full stroke soon after is high. Importantly, these strokes were not caused by heart rhythm problems, which require different treatment.
Participants were randomly assigned to receive either standard antiplatelet treatment plus a daily dose of asundexian, or standard treatment plus a placebo.
Neither the patients nor the researchers knew who was receiving which treatment during the study. Participants were followed for several months to more than two years, allowing researchers to carefully track outcomes.
The results were encouraging. People who received asundexian along with their usual antiplatelet medicine had a 26% lower risk of having another clot-related stroke compared with those who received a placebo. This benefit was seen across different ages, sexes, and stroke causes. The drug also reduced the number of strokes that led to serious disability.
Most importantly, asundexian did not increase the risk of bleeding in the brain or major bleeding elsewhere in the body. This is a major finding because bleeding risk has always been the biggest concern with stronger blood-thinning treatments.
The study also found no increase in serious side effects overall. In fact, people taking asundexian had fewer combined events such as heart attacks, strokes of any kind, major bleeding, or cardiovascular death.
Researchers believe this balance between effectiveness and safety could make asundexian suitable for long-term use. If approved, it could be added to standard treatment for many stroke survivors, offering extra protection without the usual risks that limit current therapies.
The study does have some limits. There were fewer participants with very severe strokes, so more research may be needed to understand how the drug works in those patients. Additional brain imaging studies are also still being analyzed and may provide more detail on how asundexian affects clotting and bleeding in the brain.
Overall, this research represents an important step forward in stroke prevention. It suggests that targeting clotting more precisely can reduce the risk of repeat strokes while avoiding dangerous bleeding.
If future studies confirm these results and the drug is approved, asundexian could change how doctors protect patients after a stroke. The findings support the idea that safer and more effective stroke prevention is possible, and that long-term protection does not have to come at the cost of higher bleeding risk.
If you care about stroke, please read studies about how to eat to prevent stroke, and diets high in flavonoids could help reduce stroke risk.
For more health information, please see recent studies about how Mediterranean diet could protect your brain health, and wild blueberries can benefit your heart and brain.
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