Over the years, great advances have been made in breast cancer therapy, with proven efficacy of anti-HER2 antibodies in HER2-positive tumors (trastuzumab and pertuzumab) (Costa and Czerniecki, 2020), and targeted endocrine therapy in hormone-positive cancers (ER modulators—tamoxifen, and aromatase inhibitors—anastrazole) (Tremont et al., 2017). The gene discussed is ERBB2; the disease is breast cancer.