ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Imatinib, the first-in-class oral TKI approved for treatment of CML in 2001, has pharmacological activity against ABL, BCR/ABL, platelet-derived growth factor receptor A (PDGFRA), and c-KIT on neoplastic cells, and also against ABL on normal cells [73].