<qa>  What is the maximum time period for treatment with clofarabine?Treatment: Patients in this study will be given clofarabine through intravenous infusions. This drug will initially be provided to patients for five consecutive days. Several tests will then be conducted and supportive care agents will be administered to stabilize patients blood cell counts, immune response, and reduce the risk of infection. The first ten patients in this study will be hospitalized until recovery from the first five days of clofarabine to carefully monitor any additional toxicities resulting from the dosing regimen. Patients will receive another five day treatment cycle with clofarabine within seven days after recovering from each previous cycle and no more than four weeks from the start of the previous cycle. Disease response will be measured after every two cycles of treatment with clofarabine. Patient with stable or reduced disease will receive a maximum of six treatment cycles with clofarabine. Treatments will be discontinued due to disease growth, unacceptable side effects, or a treatment delay of more than 21 days. 