AstraZeneca shares declined nearly 2% in pre-market trading on Thursday, even after the company said Tezspire, its asthma medication, met all primary objectives in a late-stage clinical trial for eosinophilic esophagitis.

The drug was co-developed with Amgen, whose shares also fell after the announcement. Both companies came under pressure despite the release of what appeared to be favorable clinical data.

According to AstraZeneca, the trial showed that Tezspire met both its primary and secondary goals. Researchers said the treatment significantly reduced inflammation in patients’ esophaguses and improved their ability to swallow compared with placebo.

Eosinophilic esophagitis is a chronic inflammatory disorder that affects more than 470,000 people in the United States. The condition can make eating difficult and cause anxiety, as food may move slowly through the esophagus or become stuck.

Tezspire works by inhibiting TSLP, a protein involved in inflammation linked to eosinophils, specialized white blood cells. The same mechanism underpins the drug’s approved use in severe asthma.

AstraZeneca said roughly half of patients with eosinophilic esophagitis, including younger patients, do not achieve adequate symptom control with existing first-line therapies. Those treatments include dietary changes, swallowed corticosteroids and proton pump inhibitor drugs. The treatment landscape has broadened in recent years: Sanofi and Regeneron’s Dupixent, which blocks interleukin-4 and interleukin-13 signaling, became the first FDA-approved treatment for eosinophilic esophagitis in 2022, and Takeda’s Eohilia, a budesonide oral suspension, was approved in 2024. Tezspire’s TSLP-targeting mechanism differs from those approaches, and the new data position it as a potential additional biologic option for patients who remain symptomatic.

Tezspire is already approved in the United States, the European Union and multiple other markets as an add-on treatment for severe asthma. The drug generated $1.13 billion in revenue for AstraZeneca in 2025.

The positive Tezspire readout comes after several development setbacks for AstraZeneca in 2026. In July, Wainua, a drug co-developed with Ionis Pharmaceuticals, missed its trial goals in transthyretin amyloid cardiomyopathy, a severe heart condition. A late-stage study of Ultomiris in rare diseases also produced disappointing results. In May, a U.S. regulatory committee declined approval for camizestrant, a breast cancer treatment, citing concerns about the trial design. More recently this month, AstraZeneca ended a clinical study of volrustomig in lung cancer after determining the drug was likely to miss its efficacy targets.

AZN stock was down 3.63% year to date entering Thursday’s session.

Despite those setbacks, Wall Street analysts remain broadly constructive on AstraZeneca. TipRanks data shows AZN carries a Strong Buy consensus rating, based on 12 Buy ratings, 1 Hold rating and 1 Sell rating.

The average analyst price target is $221.40, implying about 33% upside from current levels. The highest target on Wall Street is $275.35.

The latest esophagitis data could support Tezspire’s commercial outlook, particularly after the drug generated more than $1 billion in asthma-related revenue in 2025. If approved for eosinophilic esophagitis, Tezspire would enter a market that already includes Dupixent and Eohilia. AstraZeneca has not yet said when it plans to file for regulatory approval based on the new findings.