Elacytarabine--lipid vector technology overcoming drug resistance in acute myeloid leukemia.

INTRODUCTION: Ara-C (cytarabine arabinoside) is a deoxycytidine analog that has an established role in the treatment of hematologic malignancies, especially acute myeloid leukemia. Resistance to ara-C occurs and impacts negatively on survival. To combat this, an elaidic acid ester of ara-C, called elacytarabine, has been developed. This novel agent is highly efficacious in cells with demonstrable resistance to the parent agent, including in solid tumor xenografts. AREAS COVERED: The mechanisms that account for the increased clinical activity of elacytarabine are discussed, including its ability to bypass the specialized transmembrane nucleoside transport system on which ara-C depends, its prolonged retention within the cell and its alternative effect on the cell cycle. The development and synthesis and pharmacokinetics are outlined, with emphasis on lipid vector technology. Ten clinical trials involving elacytarabine, either as monotherapy or part of a combination regimen, have been carried out in both solid tumor and hematologic malignancies. The efficacy and side effect profile results are summarized. EXPERT OPINION: Clinical trials in patients with hematological malignancies are reporting very encouraging efficacy results with an acceptable side effect profile. Elacytarabine has the potential to play an important role in the treatment of multiple malignancies in the future and results from an ongoing Phase III clinical trial are eagerly awaited.

Current status of agents active against the T315I chronic myeloid leukemia phenotype.

INTRODUCTION: T315I is a genetic mutation of the Bcr-Abl tyrosine kinase, the pathogenetic abnormality in chronic myeloid leukemia (CML). It accounts for 10 ? 15% of clinically relevant CML mutations. Licensed tyrosine kinase inhibitors are ineffective against this mutation and its development reduces life expectancy of CML in chronic phase from 10 years to just 22 months. Extensive work is ongoing to establish the most effective therapy to overcome this mutation, including the development of novel specific agents and also re-examination of established therapies. AREAS COVERED: This review examines the agents in development, dividing them into Bcr-Abl-dependant and -independent groups. It looks at the progress of this research, updating the reader on the status of agents previously reported and introducing emerging therapeutic possibilities only recently announced. EXPERT OPINION: Development of the T315I mutation is a devastating event for some patients with CML. There are potential therapeutic agents at all stages of the drug development cycle to target this patient subpopulation. Clinical activity has been demonstrated and a number of agents are on the cusp of being licensed and available for use.