ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: According to Hughes and Ross15, optimal candidates for treatment discontinuation in clinical practice would be those fulfilling all the following criteria: (a) patients in chronic-phase CML, who have a low or intermediate Sokal risk score and a typical BCR-ABL transcript (e13a2 or e14a2); (b) at least 8 years on TKI treatment without history of resistance; and (c) sustained MR4.5 lasting ≥ 2 years.