Anti-HER-2 antibody trastuzumab deruxtecan has significantly improved the response rate (51% vs. 14%) and overall survival (12.5 vs. 8.4 months) of HER-2 positive advanced gastric cancer patients compared with chemotherapyr [11], indicating that trastuzumab deruxtecan may be less affected by high HER-2 expression due to its high drug-to-antibody ratio and membrane permeability. This evidence concerns the gene ERBB2 and gastric cancer.