Phase 1 Study of Radiosensitization Using Bortezomib in Relapsed Non-Hodgkin's Lymphoma Patients Receiving Radioimmunotherapy

This will be a multi-center, Phase I, dose-escalation study of bortezomib in combination with 131I-tositumomab in patients with relapsed non-Hodgkin's lymphoma. Bortezomib will be administered to patients twice weekly, with the first dose being given two days prior to the treatment dose of 131I-tositumomab, and the second dose two days after RIT for a total of 5 doses. Patients will be enrolled and undergo standard staging studies, including history, physical examination, complete blood count, serum chemistries and LDH, TSH, HAMA, iliac crest bone marrow biopsy, and CT scans of the chest, abdomen and pelvis. All patients will provide written informed consent. Bortezomib will be evaluated at 4 dose levels (0.30 mg/m2, 0.60 mg/m2, 0.90 mg/m2, and 1.2 mg/m2) and 131I-tositumomab at 2 dose levels (50 cGy and 75 cGy TBD). Bortezomib will be administrated the day prior to 131I-tositumomab and twice weekly thereafter for 4 doses in order to provide proteasome inhibition throughout the period of 131I-tositumomab activity. The intention is to use 131I-tositumomab at full dose if possible. Therefore, the 50cGy dose will be used only with the lowest dose of bortezomib in case of unexpected toxicities with the combination. Dose levels will be as follow: 1. 0.30mg/m2 bortezomib and 50cGy 131I-tositumomab, 2. 0.30 mg/m2 bortezomib and 75 cGy 131I-tositumomab, 3. 0.60 mg/m2 bortezomib and 75 cGy 131I-tositumomab, 4. 0.90 mg/m2 bortezomib and 75 cGy 131I-tositumomab, and 5. 1.2 mg/m2 bortezomib and 75 cGy 131I-tositumomab.