Safety and Efficacy of Pentostatin and Low Dose TBI With Allogenic Peripheral Blood Stem Cell Transplant

This is a pilot study which began with a plan to enroll 50 patients (20 related and 30 unrelated donor transplants) with hematological malignancy assessing the safety and efficacy of a minimally myelosuppressive regimen with Pentostatin and low-dose total body irradiation (TBI) followed by allogeneic peripheral blood stem cell transplantation (alloPSCT). Patients with persistent or progressive malignancy after transplantation will be treated with GM-CSF (cytokine therapy) to assess its toxicity and potential therapeutic efficacy. Patients with persistent or progressive disease who fail or do not qualify for the cytokine therapy portion of the study will become candidates for donor leukocyte infusions. The purpose of this protocol remains a pilot study which is now regarded as a phase II trial with a plan to enroll 40 ADDITIONAL patients (20 related and 20 unrelated donor transplants) with hematological malignancy assessing the safety and efficacy of a modified version of the original preparative regimen of Pentostatin and low-dose total body irradiation (TBI) followed by allogeneic peripheral blood stem cell transplantation (alloPSCT). Patients who fail will become candidates for donor-leukocyte infusion (DLI). Primary Objectives 1. To determine the safety of treating hematological malignancies by establishing donor hematopoietic chimerism using pentostatin and low-dose total body irradiation followed by allogeneic peripheral blood stem cell transplantation. 2. To determine the immunomodulatory effects of pentostatin as part of the conditioning regimen for allogeneic peripheral blood stem cell transplantation. Secondary Objectives 1. To determine the incidence of infections after using a minimally myelosuppressive conditioning regimen. 2. To determine the kinetics of hematological and immunological reconstitution after allotransplantation with a minimally myelosuppressive conditioning regimen. 3. To determine the incidence of chronic GVHD after using allogeneic peripheral blood stem cell transplantation with a minimally myelosuppressive preparative regimen. 4. To evaluate the role of the preparative regimen and donor source (related versus unrelated) on inflammatory cytokine profiles. 5. To evaluate blood and where possible, biopsy specimens for a recently identified nuclear protein (molecular weight 44/46) in mononuclear cells obtained from study subjects. Interventions, evaluation, and follow up will include: Pentostatin 4 mg/m\^2/d intravenously once a day x 3 days will be administered with 1000 cc NS hydration before and after pentostatin ten days prior to stem cell infusion (days -10, -9, and -8). Total-body irradiation (TBI): TBI 2.0 Gy will be given on day -1. Antiemetics will be given as needed. Patients will receive one liter normal saline over 2 hours pre TBI. A bone marrow biopsy and aspiration with cytogenetics and flow cytometry will be performed on Day +28, Day +70 and 6, 12, 18 and 24 months following the transplant to monitor hematologic recovery. DNA fingerprinting will also be conducted at the same time at 3, 4, 5, 6, 12, 18, and 24 months to determine chimerism.