Anti-programmed cell death protein-1 (PD-1) and programmed death ligand 1 (PD-L1) inhibitors combined with chemotherapy have become the standard of care for first-line treatment of HER2-negative, unresectable locally advanced or metastatic gastric or gastroesophageal junction (GC/GEJ) adenocarcinoma (7–11). This evidence concerns the gene ERBB2 and gastric cancer.