Sone-Ve Demonstrates Significant Overall Survival Benefit in Phase III Gastric Cancer Trial

The global Phase III CLARITY-Gastric01 trial has delivered positive high-level results for sonesitatug vedotin (Sone-Ve), demonstrating a statistically significant and clinically meaningful improvement in overall survival (OS) among patients with Claudin 18.2 (CLDN18.2)-positive advanced gastric cancers treated in the second-line and later settings. The study included patients with locally advanced or metastatic gastric cancer, gastroesophageal junction (GEJ) cancer, or oesophageal adenocarcinoma whose tumours expressed CLDN18.2 on at least 25% of tumour cells.

The trial achieved its dual primary endpoint of overall survival in patients receiving third-line or later treatment. Sone-Ve also delivered a statistically significant and clinically meaningful improvement in OS among the broader population treated in the second-line and later-line settings, meeting a key secondary endpoint. However, the other dual primary endpoint, progression-free survival (PFS) assessed through blinded independent central review, showed a positive trend but did not reach statistical significance.

Rui-Hua Xu, M.D., Ph.D., Professor in the Department of Medical Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China, and principal investigator of the trial said: “Metastatic gastric cancer is an aggressive disease with very limited options once patients progress after first-line treatment. Sone-Ve is the first CLDN18.2-targeted antibody drug conjugate to demonstrate an overall survival benefit in this setting and has the potential to establish a new precision treatment for a broader population of patients with CLDN18.2 expression.”

Advanced and metastatic gastric and GEJ cancers continue to have a poor prognosis, with fewer than 20% of patients surviving beyond one year. CLDN18.2 has emerged as a promising therapeutic target, with approximately 60% of gastric and GEJ cancers estimated to express the protein in at least 25% of tumour cells. The company estimates that around 183,500 patients across the US, EU, China and Japan are treated annually in the second-line and later settings for advanced or metastatic CLDN18.2-positive, non-HER2-positive gastric and GEJ cancers.

Susan Galbraith, Executive Vice President, Oncology Haematology R&D, said: “Sone-Ve has the potential to reshape the treatment of gastric cancer by replacing classic chemotherapy with this novel targeted antibody drug conjugate to improve outcomes for patients. These transformative results from the first Phase III readout for Sone-Ve, together with our broad development programme, highlight the potential for Sone-Ve to become an important new medicine in CLDN18.2-positive cancers.”

Sone-Ve was generally well tolerated, with its safety profile remaining consistent with previously established data and no new safety signals identified. The therapy is being developed as a potential first-in-class CLDN18.2-targeting antibody-drug conjugate (ADC) carrying a monomethyl auristatin E (MMAE) payload. The latest findings are expected to be presented at an upcoming medical meeting and submitted to regulatory authorities worldwide. Sone-Ve has already received Orphan Drug Designation in the US and Europe for gastric and GEJ cancers, as well as Breakthrough Designation in China for second-line gastric cancer.