As an example, patients with metastatic colorectal cancer (mCRC), whose tumors are mutated in exons 2-3-4 of either Kirsten rat sarcoma (KRAS) or of neuroblastoma RAS viral oncogene homolog (NRAS) genes, are not eligible for target therapy with monoclonal antibodies against epidermal growth factor receptor (EGFR) protein (4–7). This evidence concerns the gene NRAS and metastatic colorectal cancer.