AstraZeneca Stomach Cancer Drug Sonesitatug Vedotin Doubles Survival Time in Phase III Trial

AstraZeneca's experimental antibody-drug conjugate sonesitatug vedotin, known as Sone-Ve, doubled overall survival time for patients with advanced stomach cancer in a late-stage clinical trial, boosting the drug's prospects as a potential blockbuster. The results come from the CLARITY-Gastric01 global Phase III trial, which tested Sone-Ve against investigator's choice of therapy in patients with Claudin-18.2-positive gastric or gastroesophageal junction cancers who had received at least two prior lines of treatment.

CLARITY-Gastric01 is the first Phase III trial to demonstrate an overall survival benefit with an anti-CLDN18.2 antibody-drug conjugate in this setting, and it marks the first pivotal readout from AstraZeneca's wholly owned ADC portfolio. The trial met its dual primary overall survival endpoint with results described as statistically significant and highly clinically meaningful. Notably, the benefit was seen in patients with CLDN18.2 expression as low as 25%, a lower threshold than competing therapies require, meaning Sone-Ve could be eligible for roughly 60% of patients in this later-line setting, a population estimated at more than 180,000 people across the US and major European markets.

AstraZeneca presented the full data at the European Society for Medical Oncology Congress in a Presidential Symposium session during the October 23 to 27, 2026 meeting. The drug is AstraZeneca's second ADC to demonstrate an overall survival benefit in gastric cancer, following Enhertu, and the company's third positive Phase III readout in the tumor type within two years.