As examples, the use of EGFR mutation/erlotinib1, KIT mutation/imatinib2, BRAF mutation/vemurafenib3, ALK translocation/crizotinib4, and high tumor mutation burden or microsatellite instability high/pembrolizumab5–8, have dramatically changed the treatment landscape in many cancers including, but not limited to melanoma, non-small cell lung carcinoma (NSCLC), colorectal carcinoma (CRC), and head and neck (HN) cancers. The gene discussed is KIT; the disease is colorectal carcinoma.