Results from AstraZeneca’s Phase III CLARITY-Gastric01 trial showed its experimental sonesitatug vedotin doubled median overall survival in a later-line patient group, while another co-primary measure in the broader population missed statistical significance.
The findings were presented at the European Society for Medical Oncology Congress in Madrid on Sunday, Oct. 25. AstraZeneca reported a data cutoff of May 31, 2026.
In the third-line-or-later group, median overall survival was 10 months with sonesitatug vedotin, also called Sone-Ve, compared with five months with investigator-selected therapy. AstraZeneca said the result represented a 53% lower risk of death during the analysis period.
In the broader second-line-or-later population, median overall survival was 10.6 months with Sone-Ve and 6.4 months with the comparison treatment. The analysis found a 42% reduction in the risk of death among patients in the broader population.
Progression-free survival was the trial’s other co-primary endpoint. In the second-line-or-later population, median progression-free survival was 4.2 months with Sone-Ve and 3.8 months with investigator-selected therapy; AstraZeneca said the difference was not statistically significant.
Grade 3 or higher treatment-related adverse events occurred in 36.4% of patients receiving Sone-Ve and 44.8% of those in the comparison group. AstraZeneca said its safety review identified no additional signals.
Sone-Ve is an experimental antibody-drug conjugate directed at CLDN18.2, a protein expressed by cells in the stomach lining. The trial included tumors with CLDN18.2 expression in at least 25% of tumor cells. AstraZeneca estimates about 60% of patients in this setting meet that threshold.
Bloomberg News reported that AstraZeneca put Sone-Ve’s potential annual sales at $3 billion to $5 billion; the figure was not in the company’s public trial announcement. Bloomberg also reported that Barclays analyst James Gordon cited possible cost constraints in China and local fast followers as investor concerns.
AstraZeneca is also studying Sone-Ve as a first-line treatment in the Phase III CLARITY-Gastric02 trial, in combination with capecitabine, with or without rilvegostomig.
