ERBB2 and breast cancer: Over the past few decades, a great deal of molecular target drugs, for instance, monoclonal HER2-targeting antibodies (trastuzumab and pertuzumab) and antibody-drug conjugates (ADCs) (trastuzumab deruxtecan and trastuzumab emtansine), had been approved for the treatment of HER2-positive breast cancer or metastatic breast cancer (4, 5).