The Federal Drug Agency (FDA) has so far approved a number of monoclonal antibodies targeting colorectal cancer: (1) anti-EGFR (epidermal growth factor receptor), i.e., cetuximab, panitumumab [37]; (2) anti-BRAF (v-Raf murine sarcoma viral oncogene homolog B1), i.e., encorafenib [38]; (3) anti-KIT/PDGFR, i.e., regorafeni [39]; (4) anti-PD1 (programmed cell death, i.e., nivolumab [40]; (5) anti-CTLA-4 (cytotoxic T-lymphocyte-associated protein-4), i.e., ipilimumab [41,42]. The gene discussed is CTLA4; the disease is colorectal cancer.