BCR and chronic myelogenous leukemia, BCR-ABL1 positive: The role of imatinib in managing these conditions is derived directly from its mechanism of action: it is a tyrosine kinase inhibitor targeting BCR/ABL (used in chronic myeloid leukemia), KIT (used in gastrointestinal stromal tumors), FMS (receptor for colony-stimulating factor 1), and PDGFR alpha and beta (used in DFSP) [20].