90 Y-BC8-DOTA Monoclonal Antibody, Fludarabine Phosphate, and Total-Body Irradiation Followed by Donor Peripheral Blood Stem Cell Transplant in Treating Patients With Multiple Myeloma

PRIMARY OBJECTIVES: I. To assess the tissue localization of 111In-BC8-DOTA antibody therapy (Ab) and establish reproducibly favorable biodistribution. II. To estimate the maximum tolerated dose (MTD) of radiation delivered via 90Y-BC8-DOTA Ab when combined with fludarabine phosphate (FLU) and 2 Gy total-body irradiation (TBI) as a preparative regimen followed by human leukocyte antigen (HLA)-matched, related or unrelated hematopoietic cell transplant (HCT) for patients with multiple myeloma. SECONDARY OBJECTIVES: I. To assess the potential efficacy of this approach, within the limits of a phase I study, by examining disease response, duration of remission, disease free survival (DFS), and overall survival (OS). OUTLINE: This is a dose-escalation study of yttrium Y 90 anti-CD45 monoclonal antibody BC8 (90Y-BC8 Ab). Patients receive 90Y-BC8 Ab intravenously (IV) on day -12 and fludarabine phosphate IV on days -4 to -2. Patients undergo TBI and allogeneic peripheral blood stem cell transplant on day 0. Patients also receive graft-vs-host disease prophylaxis comprising cyclosporine orally (PO) twice daily (BID) on days -3 to 56 with taper to day 180 or on days -3 to 100 with taper to 180; and mycophenolate mofetil IV or PO BID on days 0-27, or 0-40 with taper to 96. After completion of study treatment, patients are followed up every 6 months for 2 years, and then annually thereafter.