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Bayer’s experimental blood thinner cuts risk and severity of repeat strokes

By Thomson Reuters May 6, 2026 | 3:36 AM

May 6 (Reuters) – Bayer’s experimental blood thinner reduced both the frequency and severity of recurrent ischaemic strokes in a large phase III trial, without increasing the risk of serious ​brain bleeds, the company said on Wednesday.

Reporting more details on ‌a trial it reported to be a success in November, the German drugmaker said that 6.2% of patients taking drug candidate asundexian experienced another ischaemic stroke, compared with 8.4% in the placebo group.

Additionally, strokes that occurred in the asundexian ‌group ​were less likely to be moderate to severe ⁠in the study involving ⁠12,327 patients.

There were also fewer cases of disability-causing and fatal strokes, as well as emergency interventions, such as clot-busting drugs or mechanical clot removal.

Bayer is betting on asundexian to offset declining revenue ​from older blockbuster drugs, such as its blood thinner Xarelto, which has faced competition from cheaper generics after losing patent protection. ⁠However, the company refrained from providing a ⁠peak sales estimate for the experimental drug, which it ​has previously described as having blockbuster potential.

The detailed trial results come ​after a setback in 2023, when asundexian failed to prevent ‌first strokes in atrial-fibrillation patients during an earlier trial.

Addressing a common concern about side effects of anticoagulant drugs, the latest study also showed that the rates of intracranial bleeding and bleeding strokes were low ⁠and comparable between the asundexian and placebo groups, including among high-risk patients, Bayer said.

The company stated that it is in discussions with health authorities globally ⁠regarding regulatory approval ‌for asundexian. According to the World Health Organization, ⁠stroke is the third-leading cause of death and ​disability worldwide, ‌with the lifetime risk of stroke increasing by ​50% over ⁠the past two decades.

Bayer faces competition from rivals, including Novartis with abelacimab and a joint effort by Bristol Myers Squibb and Johnson & Johnson developing milvexian, both of which have yet to report late-stage stroke-prevention data.

(Reporting by Patricia Weiss, writing by Linda Pasquini, Kirsti Knolle;Editing by Ludwig Burger ​and Elaine Hardcastle)