Compassionate Use of 131I-MIBG for Patients With Malignant Pheochromocytoma

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.