Ever-advancing chronic myeloid leukemia treatment

Treatment of chronic myeloid leukemia (CML) has been drastically changed by the emergence of the ABL tyrosine kinase inhibitor (TKI), imatinib mesylate. However, resistance and intolerance have frequently been reported, particularly in patients with advanced-stage disease. Point mutations within the ABL kinase domain that interfere with imatinib binding are the most critical cause of imatinib resistance. To overcome this resistance, four second-generation ATP competitive ABL TKIs, dasatinib, nilotinib, bosutinib and bafetinib, have been developed. Dasatinib and nilotinib also demonstrated higher efficacy than imatinib in previously untreated CML patients in chronic phase. Despite promising clinical results, the frequently observed mutant T315I is not effectively targeted by any of the second-generation ABL TKIs. Thus, a third-generation ABL TKI, ponatinib, was developed to inhibit all mutated BCR-ABL and showed clinical efficacy in CML cells harbouring T315I. CML treatment is rapidly progressing and further evolution is surely expected. Moreover, it was recently reported that some CML patients who achieved sustained complete molecular response could stop TKI. CML may become the first human cancer to be conquered solely with oral medicines.