AstraZeneca and Amgen co-develop and co-commercialize Tezspire under an April 2012 agreement. The partners are now planning another FDA submission for the asthma drug, which received an expansion into chronic rhinosinusitis last year.
AstraZeneca and Amgen’s anti-inflammatory therapy Tezspire, already approved in asthma and chronic rhinosinusitis, aced both co-primary and all secondary key endpoints in a late-stage study of eosinophilic esophagitis—a win that could set the subcutaneous drug up for a label expansion.
“The positive results support a potential third indication for Tezspire,” William Blair analysts wrote in a note to investors Thursday morning following the announcement. “EoE is estimated to affect more than 470,000 patients in the U.S. and is increasing in prevalence, which we believe supports an attractive third indication for Tezspire with blockbuster potential.”
The Phase 3 CROSSING study enrolled nearly 370 patients with symptomatic and histologically active eosinophilic esophagitis (EoE), a chronic inflammatory disease that damages the esophagus lining and makes it hard to swallow (dysphagia). Participants were given a high or low dose of Tezspire or placebo. CROSSING’s co-primary endpoints were histologic remission and the frequency and severity of dysphagia.
At 24 weeks, both of these metrics achieved statistically significant improvements among patients on Tezspire, according to a Thursday morning release. These effects were maintained through 52 weeks of follow-up. The drug also hit all key secondary efficacy outcomes, including histologic severity.
The pharma partners didn’t provide specific data in their press announcement but promised to do so at an upcoming medical congress. The companies also plan to share CROSSING’s outcomes with regulatory authorities “as quickly as possible,” according to Sharon Barr, executive vice president of AstraZeneca’s biopharmaceuticals R&D.
Tezspire is a humanized monoclonal antibody that works by binding to the TSLP cytokine, which plays a key upstream role in the inflammatory cascade. The drug was originally developed by Amgen but gained AstraZeneca as a collaborator under an April 2012 agreement.
Tezspire first won the FDA’s approval in December 2021 for severe asthma in patients 12 years and older. In March 2025, the partners touted strong Phase 3 data for the drug in chronic rhinosinusitis with nasal polyps, which paved the way for a nod in this indication months later. The partners are also running a late-stage study of Tezspire in chronic obstructive pulmonary disease.
AstraZeneca and Amgen haven’t yet provided a specific timeline for a regulatory submission in EoE, but CROSSING’s outcome on Thursday could set the stage for a similar expansion for Tezspire. Indeed, Leerink Partners in an Aug. 5 note flagged the readout as a key event to watch for Amgen.
In 2025, Tezspire generated $1.48 billion in U.S. sales for Amgen and $1.13 billion in ex-U.S. sales for AstraZeneca. William Blair projects those numbers could climb to around $2.0 billion and $2.4 billion, respectively.
Editor’s note (Aug. 27): This story has been updated to include comments from William Blair.
