In the CheckMate649 trial, the superiority of combined chemotherapy plus nivolumab, an anti-PD-1 antibody, over chemotherapy alone as first-line treatment was examined in HER2-negative advanced or recurrent gastric adenocarcinoma/esophagogastric junction adenocarcinoma/esophageal adenocarcinoma [131, 134]. This evidence concerns the gene ERBB2 and gastric adenocarcinoma.