GSK shares fell after the U.K. drugmaker said it would stop working on an experimental treatment for chronic cough that showed limited efficacy in late-stage clinical studies.

Shares in GSK were down 3.7% in European afternoon trading Friday, reducing the stock's year-to-date gain to 3.3%.

The move could add to investors' concerns about GSK's upcoming loss of patent protection for HIV drugs and fuel skepticism about its ability to deliver on its 2031 sales target.

The company is aiming to deliver sales of more than 40 billion pounds ($53.92 billion) in 2031. Analysts currently estimate sales at 34.88 billion pounds, according to consensus figures compiled by the company.

GSK has previously forecast the drug, camlipixant, to generate more than 2.5 billion pounds in annual peak sales.

The drugmaker on Friday reported mixed results for camlipixant across two late-stage studies in adults with chronic cough. One of the studies met the primary objective of significant reductions in cough frequency after 12 weeks of treatment, while the other didn't after 24 weeks, the company said.

A lower dose of camlipixant fell short of achieving significant reductions in both studies, and other secondary goals were also missed, GSK said.

The aggregate data point to limited efficacy that is unlikely to transform patient care, GSK said. As a result, the company decided to discontinue further development of camlipixant in refractory chronic cough, it added.

A midstage trial for the same drug in adults with irritable bowel syndrome with diarrhea and mixed bowel habits will continue to evaluate its efficacy and safety, GSK said.

GSK gained control over the medicine through its $2 billion purchase of Canada's Bellus Health in 2023, and had initially expected the drug to start to contribute to its earnings in 2027. The medicine targets the same protein as Lyfnua, a drug marketed by U.S. rival Merck.

Analysts at J.P. Morgan said GSK would likely need to book a write-down on the program.

Write to Adria Calatayud at adria.calatayud@wsj.com

(END) Dow Jones Newswires

July 17, 2026 08:52 ET (12:52 GMT)

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