In breast cancer, Upton [9] et al. demonstrated enhanced phagocytosis of tumor-associated macrophages by blocking the CD47 / SIRP α checkpoint to enable trastuzumab-mediated phagocytosis of HER2 tumor cells by trastuzumab-mediated macrophages, suggesting that the use of CD47 / SIRP α checkpoint to block the combination of trastuzumab with trastuzumab for the treatment of HER2 breast cancer (BC) and other drug-resistant HER2 cancers (i.e., gastric cancer, bladder cancer, etc.)with therapeutic potential. This evidence concerns the gene CD47 and gastric cancer.