Patients with high (2+/3+ ICH ≥ 75% of tumor cells) or intermediate (2+/3+ IHC ≥ 50% but <75% of tumor cells) CLDN18.2 expression advanced or GAC or gastroesophageal junction adenocarcinoma (GEJ) were divided into one of three cohorts: (1) high CLDN18.2 expression patients for third-line or later zolbetuximab monotherapy, (2) high CLDN18.2 expression, HER2-negative patients for first line zolbetuximab plus FOLFOX, or (3) high or intermediate CLDN18.2 expression patients for third-line or later zolbetuximab plus pembrolizumab. Here, ERBB2 is linked to neoplasm.