ERBB2 and breast cancer: In HER2-positive breast cancer, based on the results of the APHINITY trial, sequential administration of docetaxel + trastuzumab + pertuzumab and anthracyclines is commonly used in locally advanced breast cancer, and a therapeutic strategy of sequential administration of T-DM1 has been developed as an additional treatment for patients who have failed to achieve pCR with preoperative chemotherapy.