Targeted therapy of neuroblastoma with I-131 MIBG: Experience in 15 cases

Full text: I-131 MIBG has been proven to be an effective therapeutic option in neuroblastoma targeted both at the primary tumor and its distant metastasis. We describe our initial experience in the targeted treatment of 15 patients with neuroblastoma. The patients were grouped and treated according to three protocols. Group 1: patients were in the advanced stage of the disease with either metastatic or unresectable disease; Group II: patients were treated immediately after diagnosis before surgery or any other management. Group III patients were treated with combined I-131 MIBG and high dose chemotherapy. The method of administration was by slow infusion (120min). Dose varied from 4 to 12 GBq in a single dose. All patients were followed up with periodic blood counts, liver and kidney function tests, thyroid and adrenal function tests. The response rate in group-I was 38%, group-II patients showed 52% and in group-III the overall response rate was 72.6%. Responses depended on high tumoral I-131 MIBG uptake and limited spread of the neoplasm. As regards toxicity, the major side effect observed was myelosuppression and this was found to be more severe in patients with bone marrow involvement and after chemotherapy. Toxicity was relatively mild in the neuroblastoma patients who were treated at diagnosis. There was no incidence of serious infections or significant bleeding in any of our patients. Extramedullary toxicity of hypothyroidism was observed in 1 patient. On the basis of the results, we can conclude that MIBG is an excellent pharmaceutical for the delivery of therapeutic doses of radioiodine for neuroblastoma. When combined with chemotherapy it is effective in obtaining a rapid response in heavily pre-treated patients who are resistant to other therapies. (author)