ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Since imatinib alone has little or no measurable effect and does not potentiate the effects of established cytotoxic treatment in BCR–ABL-negative cells at therapeutically relevant concentrations, even merely additively acting imatinib-containing combinations as shown in CML cells should exert more selective toxicity on the leukaemic cell clone as compared with either chemo- or radiotherapy alone.