So far, the FDA has approved several targeted therapies to treat HER2-positive BC, including monoclonal antibodies (mAb), such as trastuzumab, pertuzumab, tyrosine kinase inhibitors (lapatinib, neratinib, tucatinib), and antibody-drug conjugates (DS-8201a, T-DM1, TDxd). This evidence concerns the gene ERBB2 and breast cancer.