Radiation Therapy Using Holmium Ho 166 DOTMP Plus Melphalan and Peripheral Stem Cell Transplantation in Treating Patients With Multiple Myeloma

OBJECTIVES: I. Determine the maximum tolerated dose of targeted radiotherapy using holmium Ho 166 DOTMP when combined with melphalan and autologous or syngeneic peripheral blood stem cell transplantation in patients with multiple myeloma. II. Determine the response rate and time to progression in patients treated with this regimen. OUTLINE: This is a dose escalation, multicenter study of targeted radiotherapy using holmium Ho 166 DOTMP. Phase I: Autologous or syngeneic peripheral blood stem cells (PBSC) are harvested and selected for CD34+ cells. Patients receive an initial test dose of holmium Ho 166 DOTMP IV. Patients with adequate skeletal uptake of the test dose then receive therapeutic dose holmium Ho 166 DOTMP IV over 5-10 minutes for 1-3 days beginning 2 days after test dose infusion and melphalan IV over 20-30 minutes on day -3. PBSC are reinfused beginning a minimum of 24 hours after melphalan infusion and after ongoing radiation to bone marrow falls to less than 1 rad/hour. Cohorts of 4-7 patients receive escalating doses of targeted radiotherapy using holmium Ho 166 DOTMP until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 7 patients experience dose limiting toxicity. Phase II: Patients receive holmium Ho 166 DOTMP at the MTD from phase I of the study. Patients are followed every 3 months for 1 year. PROJECTED ACCRUAL: A total of 50 patients will be accrued for this study within 1 year.