ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: It has been estimated that 28 to 36% of CP-CML patients receiving imatinib frontline or after interferon achieved a sustained DMR defined as BCR-ABL1/ABL1 4 log (MR4) or 4.5 (MR4.5) log reduction sustained for at least two years [18,19].