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

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.

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.

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.