Novel and emerging drugs for acute myeloid leukemia: pharmacology and therapeutic activity

For the last twenty years, significant progress in Molecular and Cellular Biology has resulted in a better characterization and understanding of the biology and prognosis of acute myeloid leukemia (AML). These achievements have provided new opportunities for the development of innovative, more effective therapies. Novel agents potentially useful in the treatment of patients with AML include new formulations of established drugs, newer nucleoside analogs, molecular target drugs, monoclonal antibodies and other agents. Three newer nucleoside analogs, clofarabine, troxacitabine and sapacitabine have been recently investigated in patients with AML. Two methylation inhibitors, 5-azacyticline and decitabine are pyrimidine nucleoside analogs of cytidine which can be incorporated into RNA and/or DNA. Lower doses of these agents are active in AML and have been extensively investigated, especially in secondary AML and AML in elderly patients. Tipifarnib and lonafarnib are orally available farnesyltransferase inhibitors with in vitro and in vivo activity against AML. In recent years, FLT3 inhibitors, lestaurinib, tandutinib and PKC 412 have been developed and tested in AML. The preclinical observations and clinical studies indicate that FLT3 inhibitors are promising agents in the treatment of FLT3 mutated AML patients, especially when used in combinations with chemotherapy. Several newer MDR inhibitors, including valspodar (PSC-833) and zosuquidar trihydrochloride have been also tested for the treatment of relapsed AML. This article reviews the various classes of AML targets and drugs that are under early phase clinical evaluation, especially those that are likely to enter clinical practice in the near future.