The success of the first-line therapy option BCR-ABL inhibitor imatinib has been opposed with drug resistance that occurs due to both intrinsic and extrinsic factors including ABL-kinase region mutations, BCR-ABL gene amplification/overexpression, clonal evolution, the presence of CML stem cells, the overexpression of MDR1 (multidrug resistance protein 1), and decreased drug bioavailability (Apperley 2007). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.