Bayer Shares Jump After Drug Candidate Shows Stroke Prevention Potential — Update

By Aimee Look

Shares in Bayer rose after the company reported positive results from a clinical trial for an experimental stroke-preventing drug which had previously showed to be ineffective in another trial.

The German conglomerate is trying to turn around its pharmaceutical business--hit in recent years by pipeline setbacks and top-line pressure from key drugs going off patent--as it pushes ahead with a major restructuring and continues to tackle U.S. legal cases.

Bayer said Sunday that the once-daily 50mg asundexian medication, when combined with antiplatelet therapy, lowered the risk of stroke in patients during a late-stage trial, meeting the primary objective of the study.

Shares in Bayer rose as much as 12% in European morning trading, meaning that the stock has now gained more than 50% since the start of the year.

The company said the phase 3 trial evaluated asundexian alongside standard antiplatelet therapy in reducing stroke risk for those who had already experienced a first stroke. It did so without causing major bleeding, a side effect of other blood thinning medications, according to Bayer.

The drug blocks Factor XIa, a protein that contributes to blood clotting, the company said.

Bristol Myers Squibb and Johnson & Johnson are developing another experimental drug, milvexian, that uses the same mechanism. Shares in Bristol Myers Squibb were up 3.8% in U.S. premarket trading.

The asundexian trial results give Bayer confidence in the drug class, the research-and-development head of its pharma division, Christian Rommel, said.

The company said it will work with global health authorities as it prepares marketing authorization applications for asundexian.

"This is a material de-risking event for Bayer's pipeline," analysts at Jefferies wrote in a note. "We see this as a key driver for the pharma backlog, unlocking a significant revenue opportunity in secondary stroke prevention."

Bayer's successful trial comes after it previously halted a phase 3 clinical trial testing the effectiveness of the same experimental drug for stroke and systemic embolism prevention in 2023. At the time, the trial's discontinuation dealt a blow to Bayer's pharmaceutical division, as it was expected to bring the division back to growth.

The division is facing headwinds due to generic competition for two of its biggest drugs, anticoagulant Xarelto and ophthalmology medicine Eylea. However, Bayer expects fast-growing sales of Nubeqa for the treatment of prostate cancer, Kerendia for chronic kidney disease, and recently launched treatments such as Lynkuet for hot flashes can help it mitigate the hit.

Meanwhile, Bayer is faces legal battles in the U.S., which led it to add 1.06 billion euros ($1.22 billion) in charges to last quarter's earnings. It is up against thousands of unresolved claims related to its herbicide glyphosate's alleged links to cancer, which the company disputes.

Write to Aimee Look at aimee.look@wsj.com

(END) Dow Jones Newswires

November 24, 2025 06:12 ET (11:12 GMT)