The KEYNOTE-811 trial of pembrolizumab plus trastuzumab and chemotherapy for patients with HER2-positive gastric cancer demonstrated a statistically significant 22.7% improvement in ORR in the pembrolizumab group compared with the placebo group (77.4% vs. 51.9%, p ≥ 0.00006) [45]. This evidence concerns the gene ERBB2 and gastric cancer.