Targeted therapy drugs that target the genes K-ras (KRAS) proto-oncogene, GTPase (KRAS), B-Raf proto-oncogene serine/threonine kinase (BRAF), and SMAD family member 4 (SMAD4) are used with chemotherapy regimens to treat CRC. The gene discussed is SMAD4; the disease is colorectal carcinoma.