This is a dose-escalation study to determine the maximum tolerated dose and toxic effects of
clofarabine in patients with chronic lymphocytic leukemia and other acute leukemias.
Clofarabine is a synthesized hybrid nucleoside analog, which is believed to possess the
better qualities of fludarabine and chlorodeoxyadenosine, the 2 most active agents against
lymphoproliferative disorders. Thus, it is hoped that this drug will be more active and less
toxic than similar drugs.