KIT and gastrointestinal stromal tumor: Imatinib, a tyrosine kinase inhibitor targeting Bcr–Abl, KIT, and PDGFRA, is approved as a first-line therapy for patients with unresectable metastatic or recurrent GIST (6, 7) and has demonstrated remarkable clinical activity with a median progression-free survival (PFS) of 24 months and a 68% overall response rate (ORR).