Nelarabine is a nucleoside analog prodrug of 9-beta-D-arabinofuranosylguanine. Nelarabine is indicated for the treatment of adult and pediatric patients with T-cell acute lymphoblastic leukemia or T-cell lymphoblastic lymphoma whose disease has not responded to, or has relapsed after treatment with, at least two chemotherapy regimens. Nelarabine was granted Orphan Medical Product Status in Europe in June 2005, and accelerated approval by the US FDA in October 2005. The most common adverse events associated with nelarabine are neurotoxic in nature and have been dose-limiting.