CSPC PHARMA and Alphamab Oncology's HER2 bispecific ADC (BsADC) anbenitamab repodatecan has posted striking early efficacy in first-line HER2-positive, PD-L1 CPS≥1 unresectable locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma (GA/GEJA), with confirmed objective response rates (ORR) of 71.4% in cohort A, 100% in cohort B and 50.0% in cohort C across 25 patients. Cohort B paired anbenitamab repodatecan with the PD-1 antibody enlonstobart, capecitabine and the HER2 bispecific anbenitamab, while cohort C substituted oxaliplatin and enlonstobart. Duration of response, progression-free survival and overall survival remain immature at this stage.

Safety shapes the commercial and development readout as much as efficacy. Appetite loss and anaemia each occurred in 56.0% of patients, with low albumin, thrombocytopenia, nausea and diarrhoea also common, and grade 3 or higher treatment-related adverse-event (TRAE) rates diverged sharply by regimen: 57.1% in cohort A, 28.6% in cohort B and 100% in cohort C, with no treatment-related deaths.