ERBB2 and gastric cancer: CheckMate-649 had the largest sample size of GC patients to date and compared the therapeutic effect of nivolumab in combination with chemotherapy (O + chemo) or nivolumab in combination with ipilimumab (YO in combination) with that of chemotherapy alone in the untreated patients with HER2-negative, advanced or metastatic GC, gastroesophageal junction cancer, or esophageal adenocarcinoma.