Ponatinib--a step forward in overcoming resistance in chronic myeloid leukemia

With the current therapy, the improvement in survival of patient with early chronic phase chronic myelogenous leukemia (CML) is unrivaled by that of any other leukemia. In fact, extrapolation of the survival curves may suggest that life expectancy of patients who achieve and maintain predetermined milestones may not differ from that of the age-matched healthy adults. The main reasons for such success are the presence of a well-defined molecular target, the BCR-ABL oncogene, necessary and sufficient for the initiation and propagation of CML, and the powerful and selective agents that inhibit it. Five U.S. Food and Drug Administration (FDA)-approved tyrosine kinase inhibitors (TKI), each with unique activities and toxicity profiles, allow for individualized patient care. Despite the remarkable responses of most patients, a small but significant fraction of patients develops clinical resistance to the TKIs, some of which is attributed to the BCR-ABL kinase domain mutations affecting TKI binding and activity. The recently approved third-generation TKI ponatinib showed remarkable activity in the patients with multi-TKI-resistant disease. Particularly impressive was its efficacy in patients with T315I mutation that is resistant to all other TKIs. In lieu of the current emphasis on achieving earlier and more profound responses and excellent activity of ponatinib in the refractory setting, its optimal position among the available armamentarium of agents is being established.