The FDA has approved various mAbs, like cetuximab (anti-EGFR) for epithelial cancer, rituximab (anti-CD20) for lymphoma, trastuzumab (anti-HER2) for HER2-positive breast cancer, and daratumumab (anti-CD38) for multiple myeloma, etc. These mAbs leverage the body’s immune response to eliminate targeted cancer cells through different mechanisms, including the activation of immune effector cells, antibody-dependent cell-mediated cytotoxicity (ADCC), apoptosis induction, complement-dependent cytotoxicity (CDC), and receptor-mediated signaling blockade [300,301]. The gene discussed is ERBB2; the disease is breast carcinoma.