An overview of the assessment and random assignment of patients in the SPOTLIGHT and GLOW studies is presented in Supplementary Fig. S1a–b, and representativeness of all screened patients with valid CLDN18 IHC results relative to the overall population of patients with advanced G/GEJ adenocarcinoma is provided in Supplementary Table S1. The gene discussed is CLDN18; the disease is adenocarcinoma.