- Phase I: Patients receive clofarabine IV over 1 hour and low-dose cytarabine subcutaneously (SC) on days 1-5. Patients also receive filgrastim (G-CSF) SC beginning 1 day prior to the start of chemotherapy and continuing through completion of chemotherapy until blood counts recover. Treatment repeats every 6 weeks for up to 10 courses in the absence of disease progression or unacceptable toxicity.