ERBB2 and breast cancer: The therapeutic landscape for BC has expanded with the development of increasingly effective drugs, including chemotherapy, hormone therapies (e.g., tamoxifen, anastrozole, letrozole, fulvestrant), anti-HER2 monoclonal antibodies (e.g., trastuzumab, pertuzumab), and, more recently, and anti-HER2 antibody–drug conjugates (ADCs) (e.g., trastuzumab–deruxtecan, trastuzumab–emtansine, datopotamab–deruxtecan, sacituzumab–govitecan), as well as immunotherapies (e.g., pembrolizumab, atezolizumab) [4].