Sone-Ve cuts risk of death by 42% in Phase III advanced gastric cancer trial

AstraZeneca has reported positive Phase III results showing that sonesitatug vedotin, also known as Sone-Ve, significantly improved overall survival in patients with previously treated CLDN18.2-positive advanced gastric and gastroesophageal junction cancers.

The findings come from the global CLARITY-Gastric01 study and were presented during a Presidential Symposium at the 2026 European Society for Medical Oncology Congress in Madrid.

Sone-Ve is an investigational antibody drug conjugate targeting Claudin 18.2, or CLDN18.2.

The Phase III study included patients with locally advanced or metastatic gastric cancer, gastroesophageal junction cancer or oesophageal adenocarcinoma whose tumours expressed CLDN18.2 on at least 25% of tumour cells at any staining intensity.

This threshold represents a broader population than definitions of CLDN18.2 positivity traditionally used for some targeted treatments.

In the overall trial population receiving treatment in the second-line setting or later, Sone-Ve reduced the risk of death by 42% compared with investigator’s choice of therapy.

The overall survival hazard ratio was 0.58, with a 95% confidence interval of 0.47 to 0.73 and a p value below 0.000004.

Median overall survival reached 10.6 months with Sone-Ve compared with 6.4 months in the control group.

The survival benefit was even greater among patients receiving treatment in the third-line setting or later.

In this population, Sone-Ve reduced the risk of death by 53%, with a hazard ratio of 0.47.

Median overall survival doubled to 10.0 months with Sone-Ve compared with 5.0 months with investigator’s choice of treatment.

AstraZeneca said the overall survival benefit was generally consistent across predefined patient subgroups.

This included patients with CLDN18.2 expression between 25% and less than 75%, as well as those with expression of 75% or higher.

The findings therefore support the potential use of Sone-Ve across a broader range of CLDN18.2 expression levels.

The trial had two primary endpoints.

Overall survival in patients receiving third-line or later treatment met statistical significance, while progression-free survival assessed by blinded independent central review in the overall second-line-and-later population showed a numerical improvement but did not reach statistical significance.

An exploratory investigator-assessed progression-free survival analysis produced a hazard ratio of 0.59, which AstraZeneca said was more consistent with the overall survival benefit observed in the trial.

Rui-Hua Xu, MD, PhD, Professor in the Department of Medical Oncology at Sun Yat-Sen University Cancer Center and principal investigator of CLARITY-Gastric01, said the survival results were notable in a population with limited treatment options after initial therapy fails.

He said Sone-Ve is the first CLDN18.2-targeted treatment to demonstrate a survival benefit in this later-line setting.

Susan Galbraith, Executive Vice President of Oncology Haematology Research and Development at AstraZeneca, said the findings support the potential for Sone-Ve to become an alternative to traditional chemotherapy-based treatment in previously treated metastatic gastric cancer.

She added that the consistent results across CLDN18.2 expression groups may allow the treatment to reach a broader population of patients.

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Related Topics and Keywords

ADC, antibody drug conjugate, AstraZeneca, Biopharma, CLARITY-Gastric01, Claudin 18.2, CLDN18.2, clinical trials, ESMO 2026, gastric cancer, gastroesophageal junction cancer, GEJ cancer, oesophageal adenocarcinoma, Oncology, overall survival, pharma news, phase III, progression-free survival, Sone-Ve, sonesitatug vedotin, targeted therapy