CheckMate 649 was a randomized, open-label, phase 3 trial that compared nivolumab plus chemotherapy, nivolumab plus ipilimumab (anti-cytotoxic T-lymphocyte-associated antigen 4 [CTLA4] inhibitor), or chemotherapy alone in previously untreated, unresectable, HER2 negative gastric, gastroesophageal junctions, or esophageal adenocarcinoma [114]. Here, CTLA4 is linked to esophageal adenocarcinoma.