ERBB2 and gastroesophageal junction adenocarcinoma: In the first-line treatment of advanced HER2-negative GC, the American Society of Clinical Oncology recommends the use of nivolumab plus chemotherapy for patients with PD-L1 CPS (Combined Positive Score) ≥5 in G/GEJ adenocarcinoma, and pembrolizumab plus chemotherapy for patients with PD-L1 CPS ≥10 in GEJ adenocarcinoma(Press et al., 2017; Shah et al., 2023) CLDN18.2 is expressed in most G/GEJ adenocarcinoma cells (Shitara et al., 2023).