KIT and chronic myelogenous leukemia, BCR-ABL1 positive: Imatinib, a selective inhibitor of the KIT protein tyrosine kinase that was developed to treat chronic myelocytic leukemia, was shown to markedly improve relapse-free survival in GIST patients [4-8] and has since emerged as the primary treatment modality for patients that have unresectable or metastatic disease [21].