ERBB2 and gastric adenocarcinoma: Combination of chemotherapy with platinum agents and fluoropyrimidine has been regarded as the standard of care in a first-line setting for unresectable or recurrent advanced gastric adenocarcinoma (AGC) [1], to which trastuzumab, an anti-HER2 monoclonal antibody, is added in HER2-positive cases [2, 3].