The condition, eosinophilic esophagitis, is characterised by inflammation and damage to the esophagus and typically requires repeated treatments, such as corticosteroids and diet change, to ease the symptoms.

In the trial, Fasenra helped improve the build-up of white blood cells in the esophagus but did not show statistically significant change in dysphagia symptoms, or swallowing difficulties, in patients aged 12 years and older, the company said.

Earlier this year, Sanofi and partner Regeneron’s Dupixent became the first treatment to target underlying causes of the disease after it gained a US approval.

Despite the setback from the trial, AstraZeneca said it would continue to analyse the complete data set, which included 210 patients, and present its results at a future medical meeting.

But, Credit Suisse analysts said in a note that it could be difficult for AstraZeneca to file for wider approvals of its drug with no patient benefit.

Fasenra reported sales of $1.26 billion in 2021 and is approved as an add-on maintenance treatment in severe eosinophilic asthma in the US, Europe and Japan and some other countries.