AstraZeneca (AZ) has reported that the Phase III CLARITY-Gastric01 study of sonesitatug vedotin, a CLDN18.2–targeted antibody–drug conjugate (ADC) originally developed by China-based Lepu Biopharma and Keymed Biosciences via their joint venture KYM Biosciences, met its primary overall survival (OS) endpoint in third-line and later (3L+) and second-line and later (2L+) advanced or metastatic gastric and gastro-oesophageal junction adenocarcinoma with CLDN18.2 expression in at least 25% of tumour cells.

The open-label, randomised trial compared sonesitatug vedotin at 1.8 mg/kg or 2.2 mg/kg every three weeks against investigator-chosen chemotherapy, with progression-free survival (PFS) in the 2L+ population showing a directional but non-significant improvement.

The result marks the first Phase III readout for sonesitatug vedotin and strengthens AZ's gastroenterological oncology portfolio alongside Enhertu (trastuzumab deruxtecan) and Datroway (datopotamab deruxtecan). With historical median OS of 5 to 9 months in later-line gastric cancer, a confirmed OS advantage addresses a high-unmet-need setting where CLDN18.2 is expressed in roughly 60% of cases at the 25% threshold.

The asset now joins China-developed CLDN18.2 ADCs from Sino Biopharmaceutical and Innovent/Takeda in the advanced regulatory queue, intensifying competition in targeted gastric cancer therapeutics.