Nelarabine: A Nucleoside Analog with Efficacy in T-Cell and other Leukemias

Abstract

OBJECTIVE:To present the pharmacology and pharmacokinetics of nelarabine, 9-β-D-arabinofuranosylguanine (ara-G) and intraleukemic cellular pharmacokinetics of 9-β-D-arabinofuranosylguanine triphosphate (ara-GTP) generated from the administration of nelarabine, and clinical and safety information relative to nelarabine use in the treatment of hematologic malignancies.DATA SOURCES:MEDLINE (1966—December 2004) was searched using the English-language key terms 2-amino-6-methoxypurine arabinoside, 506U78, and nelarabine. Data were also obtained from published abstracts.STUDY SELECTION AND DATA EXTRACTION:Clinical studies evaluating the pharmacokinetics of nelarabine, ara-G, and cellular ara-GTP and use of nelarabine, alone or in combination with other agents for the treatment of hematologic malignancies, were included in this review.DATA SYNTHESIS:Nelarabine is the water-soluble, 6-methoxy analog of 9-β-D-ara-G. Nelarabine is readily converted to ara-G by endogenous adenosine deaminase. The half-life of nelarabine is approximately 15 minutes compared with 2–4 hours for ara-G. The clearance of ara-G is higher in children than in adults (0.312 vs 0.213 L × h−1× kg−1). Intracellular ara-GTP elimination is slow relative to nelarabine and ara-G. In pediatric and adult patients, neurologic toxicity is dose limiting. Severe myelosuppression was not consistently observed. Major responses were seen in patients with T-cell malignancies. Patients who responded had significantly higher intracellular ara-GTP concentrations compared with those who did not respond.CONCLUSIONS:Nelarabine is an effective ara-G prodrug. Nelarabine has significant activity against malignant T-cells and appears to be an important addition to treatments of various leukemias.