ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Indeed, quiescent CML leukemia stem cells (LSCs) survive despite BCR::ABL1 inhibition by TKIs [5], representing a disease “reservoir” still detectable in patients in complete cytogenetic response (CCyR) [6], deep molecular response (DMR) and, surprisingly, even in stable TFR [7].