Iodine I 131 Tositumomab, Etoposide and Cyclophosphamide Followed by Autologous Stem Cell Transplant in Treating Patients With Relapsed or Refractory Non-Hodgkin's Lymphoma

PRIMARY OBJECTIVES: I. To assess the progression-free survival of patients receiving 131 I labeled tositumomab antibody, etoposide (VP-16) and cyclophosphamide (CY) followed by autologous transplantation. II. To examine the potential efficacy of 131 I labeled tositumomab antibody, etoposide (VP-16) and cyclophosphamide (CY) followed by autologous transplantation. SECONDARY OBJECTIVES: I. To assess the overall survival of patients receiving 131 I labeled tositumomab antibody, etoposide (VP-16) and cyclophosphamide (CY) followed by autologous transplantation. II. To evaluate the toxicity and tolerability of the above therapy. OUTLINE: RADIOIMMUNOTHERAPY: Patients receive a test dose of iodine I 131 tositumomab intravenously (IV) on day -24 to determine biodistribution. Patients then receive therapeutic iodine I 131 tositumomab IV over approximately 40-60 minutes on day -14 and are entered into radiation isolation until day -4. CHEMOTHERAPY: Patients receive etoposide IV on day -4 and cyclophosphamide IV on day -2. AUTOLOGOUS STEM CELL TRANSPLANTATION: Patients undergo autologous peripheral blood stem cell transplant on day 0. After completion of study treatment, patients are followed at 1, 3, 6, and 12 months and then annually thereafter.