Dasatinib: the emerging evidence of its potential in the treatment of chronic myeloid leukemia

INTRODUCTION: Current therapy options for chronic myeloid leukemia (CML) include conventional chemotherapy, allogeneic stem cell transplant, interferon-alfa, and imatinib mesylate, which has recently achieved gold standard status. Although the majority of patients initially respond well to treatment with imatinib, wider clinical experience with this drug has resulted in the development of imatinib resistance being increasingly documented. There is therefore an unmet medical need for novel therapies to override imatinib resistance in CML. AIMS: This review summarizes the emerging evidence for the potential use of dasatinib in the treatment of imatinib-resistant CML. DISEASE AND TREATMENT: Dasatinib is a novel small molecule that has shown potent antileukemic activity in imatinib-resistant cell lines, malignant marrow cells isolated from patients with imatinib-resistant CML, and in mouse xenograft models of imatinib-resistant CML. Preliminary data from an initial phase I dose escalation trial have been encouraging, indicating that dasatinib is generally well tolerated and produces hematologic and cytogenetic responses in patients with imatinib-resistant CML in all phases of the disease. The maximum tolerated dose (MTD) has not yet been reached, and dose escalation continues to determine the dose range that yields optimal results. PROFILE: Although dasatinib is still in the early stages of development, the potential impact of this molecule on the treatment of CML could be revolutionary, not only providing a much needed treatment option for patients with imatinib-resistant CML, but also, combined with imatinib, could possibly prove useful in delaying the onset of resistance to treatment. Furthermore, combined with other agents active in CML, dasatinib could have potential utility in purging residual leukemic cells in patients whose disease is controlled by imatinib.