KIT and neoplasm: Sunitinib, a second-line treatment for GISTs following imatinib failure, is a multitargeted TKI that inhibits KIT, PDGFRA, VEGFRs, and other kinases involved in tumor growth and angiogenesis.7) Sunitinib has demonstrated efficacy in patients with imatinib-resistant GISTs, particularly those with secondary KIT mutations in the ATP-binding domain.