Drug: 131 I-Metaiodobenzylguanidine (131 I-MIBG)
Therapeutic 131I-MIBG will be synthesized at Nuclear Diagnostic Products (NDP; Rockaway, New Jersey) with specific activities of 9-18 Ci/mmole. The therapeutic dose: 8-12 mCi/kg (maximum 500 mCi ± 10% at investigator's discretion) will be diluted in 25 ml of normal saline, and will be infused intravenously through a patient's peripheral or central line over 120 minutes. The patient will remain in a radiation protected isolation room until radiation emissions are ≤ 2 mr/hr at a 1 meter distance or meets institutional and state guidelines. This usually takes 4-6 days. In all cases, special shielding will be equipped in the room to minimize exposure to the outside environment and personnel will observe institutional radiation safety precautions.
Other Name: 131I-MIBG
Pheochromocytomas (PHEO) and paragangliomas (PGL) are rare tumors, with an incidence of 2-8 cases per million annually. These tumors develop in both children and adults. About 15-20% metastasize. Chemotherapy for this tumor usually consists of a combination of cyclophosphamide, vincristine, and dacarbazine delivered over two days and repeated every 3 weeks. Such combined chemotherapy is ineffective for the majority of patients with metastatic PHEO/PGL. A few patients with malignant PHEO have experienced remissions with sunitinib, but the drug may produce severe toxicity and the experience with that drug is limited. Those patients who do experience a remission with chemotherapy must continue it indefinitely to stay in remission. However, most such patients experience such severe side effects from the chemotherapy (marrow suppression, neuropathy, etc) that their chemotherapy must be discontinued. Thus, chemotherapy is either ineffective or intolerable for the vast majority of patients with metastatic PHEO/PGL.