Frontline therapy for HER2+ breast cancer relies on extracellularly targeted anti-HER2 antibodies (Herceptin/trastuzumab and Perjeta/pertuzumab) that inhibit downstream HER2-dependent tyrosine kinase signaling pathways, facilitating antibody-dependent cell-mediated cytotoxicity [14,15,16,17,18]. The gene discussed is ERBB2; the disease is breast cancer.