Clofarabine and Non-Myeloablative Allogeneic Hematopoietic Transplantation

Inclusion Criteria: Phase I * Acute leukemia - secondary or beyond first remission or in CR with poor risk cytogenetics, myelodysplastic syndrome IPPS Int-2 or high risk, chronic myelogenous leukemia in accelerated or blast crisis and imatinib refractory or lymphoma having failed second line therapy or relapsed mantle cell lymphoma. Phase II * Acute leukemia secondary or at high risk for relapse, myelodysplastic syndrome IPPS Int-2 or high risk or having failed other therapy, chronic myelogenous leukemia, lymphoma having failed first line therapy or at high risk, relapsed Hodgkin's, CCL progressed beyond initial therapy, multiple myeloma beyond initial response or with high risk features. * Must have an HLA matched or 5/6 matched related donor at at least a 5/6 matched unrelated donor available. * Have adequate renal and hepatic functions * Capable of understanding the investigational nature, potential risk and benefits of the study and able to provide valid informed consent. * Female patients of childbearing potential must have a negative serum pregnancy test within 2 weeks prior to enrollment. * Male and female patients of childbearing potential must use an effective contraceptive method during the study and for a minimum of 6 months after study treatment. Exclusion Criteria: * Current concomitant chemotherapy, radiation therapy or immunotherapy other than as specified in the protocol. * Use of investigational agents within 30 days and no cytotoxic anticancer agents within 2 weeks before study entry with the exception of hydroxyurea. The patient must have recovered from all non-hematological acute toxicities from any previous therapy. * Other severe concurrent disease, or have a history of serious organ dysfunction or disease involving the heart, kidney, liver or other organ system that may place the patient at undue risk to undergo treatment. * Patients with systemic fungal, bacterial, viral, or other infection not controlled. * Pregnant or lactating patients. * Any significant concurrent disease, illness or psychiatric disorder that would compromise patient safety or compliance, interfere with consent, study participation, follow-up or interpretation of study results. * Age \> 70 (for Phase 1) or 75 (for Phase 2)