ERBB2 and breast cancer: Targeted [6–8] treatment against HER2 with the monoclonal antibodies trastuzumab and pertuzumab, the small molecule tyrosine kinase inhibitors lapatinib, neratinib, and tucatinib, and the antibody-chemotherapy conjugates trastuzumab emtansine and trastuzumab deruxtecan has markedly improved outcomes in patients with HER2-positive breast cancer [9–13].