AstraZeneca and Amgen’s anti-inflammatory therapy, Tezspire, which has been approved for asthma and chronic rhinosinusitis, met both of its co-primary endpoints and all its secondary key endpoints in a late-stage study of eosinophilic esophagitis, a finding that could spark a label expansion.
Market Impact and Blockbuster Potential
It’s a “potential third indication for Tezspire,” according to the analysts at William Blair who, in a note to investors Thursday morning, noted the positive results. We believe that the third indication of Tezspire has an attractive blockbuster potential and that more than 470,000 patients in the U.S. are estimated to be affected by EoE, which is growing in prevalence.
Nearly 370 patients were enrolled in the Phase 3 CROSSING study, which included those with symptomatic and histologically active eosinophilic esophagitis (EoE), a chronic immune-mediated disease that causes inflammation of the esophagus and makes swallowing difficult (dysphagia). Participants were given a high or low dose of Tezspire or placebo. Histologic remission and the number and severity of episodes of dysphagia were the co-primary endpoints of the CROSSING trial.
They both reached statistically significant improvements at 24 weeks for Tezspire patients, according to Thursday morning data. These effects lasted for 52 weeks. The drug was also found to be effective in all the important secondary endpoints such as histologic severity.
Next Steps and Regulatory Plans
The pharma partners didn’t give details in their press release but indicated that they will have information at an upcoming medical congress. The companies also intend to discuss CROSSING’s results with regulatory bodies “as soon as possible,” said Sharon Barr, EVP of AstraZeneca’s biopharmaceuticals R&D.
Tezspire is a humanized monoclonal antibody that is a binder of the TSLP cytokine, a key upstream cytokine in the inflammatory cascade. The drug was developed by Amgen, but became a joint project of Amgen and AstraZeneca under an agreement made in April 2012.
Approved Indications and Pipeline Growth
Tezspire first won the FDA’s approval in December 2021 for severe asthma in patients 12 years and older. The combined partners presented favorable Phase 3 results in March 2025 for the drug in the chronic rhinosinusitis with nasal polyps indication, which led to a nod in this indication a few months later. It is also currently conducting a late-stage study of Tezspire for chronic obstructive pulmonary disease (COPD).
AstraZeneca and Amgen have yet to give any specific timeline for a submission in EoE, but the success of CROSSING on Thursday portends a similar expansion for Tezspire. In fact, Leerink Partners noted in an Aug. 5 note that it was a readout to watch for Amgen.
Tezspire generated $1.48 billion in U.S. sales and $1.13 billion in ex-U.S. sales for Amgen and AstraZeneca, respectively, in 2025. William Blair estimates those figures might reach $2.0 billion and $2.4 billion.
Tezspire, the asthma medicine developed by AstraZeneca and Amgen, has delivered another major late-stage clinical success, this time in eosinophilic esophagitis (EoE). The Phase 3 CROSSING trial achieved both co-primary endpoints and all key secondary endpoints, strengthening the drug’s potential to expand into another inflammatory disease.
Tezspire Delivers Positive Phase 3 Results
The Tezspire CROSSING trial evaluated adults and adolescents with symptomatic and uncontrolled eosinophilic esophagitis. Patients received subcutaneous treatment every four weeks, with results compared against placebo.
At Week 24, Tezspire produced statistically significant and clinically meaningful improvements in both histologic remission and dysphagia, or difficulty swallowing. The improvements were maintained through Week 52.Following the positive CROSSING results, AstraZeneca plans to share the complete data with regulatory authorities and the scientific community at an upcoming medical meeting. The companies will need to complete regulatory discussions before any potential approval for eosinophilic esophagitis.
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