PDCD1 and gastric cancer: The CheckMate 649 trial investigated the efficacy of the anti-PD-1 antibody nivolumab and anti-CTLA-4 antibody ipilimumab in patients with advanced HER2-negative GC.104 A total of 1.581 previously untreated patients were randomized to receive either nivolumab plus chemotherapy (capecitabine with oxaliplatin or fluorouracil with leucovorin and oxaliplatin), chemotherapy alone, or nivolumab plus ipilimumab.