BCR and chronic myelogenous leukemia, BCR-ABL1 positive: The next step was established from a chronic myeloid leukemia (CML) scenario, where patients with inadequate initial responses to tyrosine kinase inhibitors (TKIs), or an increase in the level of MRD following an initial response, are commonly tested for the presence of BCR–ABL kinase domain variants that confer TKI resistance, using MRD for targeted approaches to eradicate resistant clones [12].