In May 2021, the FDA approved pembrolizumab in combination with trastuzumab and chemotherapy for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric/GEJ adenocarcinoma, regardless of PD-L1 CPS expression, based on the first analysis of KEYNOTE-811 (Janjigian et al., 2021). Here, ERBB2 is linked to gastroesophageal junction adenocarcinoma.