The requirement for more dynamic specialists have distinguished a novel purine nucleoside simple, clofarabine, which has been supported for the treatment of kids with backslid what’s more, obstinate ALL, showing additionally encouraging clinical advantage in stage I-II investigations in grown-up patients. Clofarabine (2-chloro-20- fluoro-deoxy-9-b-Darabinofuranosyladenosine) is a second-age nucleoside simple. Its system of activity is based on the hindrance of both DNA combination and the chemical ribonucleotide reductase, bringing about a decrease of the intracellular pool of deoxynucleoside triphosphates accessible for DNA replication. Also, the triphosphate type of clofarabine is consolidated into DNA, deciding an untimely DNA chain end.