KIT and gastrointestinal stromal tumor: Following resistance to imatinib mesylate, sunitinib, a multitargeted small-molecule tyrosine kinase inhibitor that selectively blocks vascular endothelial growth factor receptors (VEGFRs) with potent activity against KIT and PDGFA, has proven effective as a second-line therapy and is currently approved worldwide for metastatic GIST in patients with imatinib resistance or intolerance [7, 8].