BCR and chronic myelogenous leukemia, BCR-ABL1 positive: In chronic myeloid leukemia (CML) with a BCR-ABL fusion gene, treatment with tyrosine kinase inhibitors (TKis) specifically targeting BCR-ABL results in remission and prolongation of survival in most patients; however, 60–70% of CML patients may become insensitive to the drug by developing acquired resistance in the chronic phase [10].