Approximately 80 % of GIST patients have a mutation in c-kit, and 10 % harbor a mutation in PDGFRA. Therefore, development of TKIs of imatinib, sunitinib, and regorafenib targeting both KIT and PDGFRA tyrosine kinases is being vigorously advanced. The gene discussed is KIT; the disease is gastrointestinal stromal tumor.