Role of {[I-131]metaiodobeuzylguanidine (MIBG) in the treatment of neuroblastoma: A review}

For years there has been no substantial improvement in survival rates of children with advanced neuroblastoma (NB). NB is a radiosensitive tumor. Since promising results are obtained with aggressive chemotherapy, it might be expected that even better results could be obtained from a high radiation dosage. But delivery of high radiation doses is limited by host intolerance. {[I-131]Metaiodobeuzylguanidine ([I-131]MIBG), a radioiodinated aralkylguanidine, is capable of competing with norepinephrine for uptake into neuroadrenergic tissue and derived tumors. Targeted radiotherapy with elevated doses has been pioneered by several groups, as a high dose of radioactivity can be selectively delivered to tumor cells, with an acceptable systemic toxicity. We briefly review here the latest research achievements and the progress that has been made with the use of this new treatment modality in patients with advanced NB. Encouraging results have been obtained with [I-131]MIBG in patients with resistant disease; however, a promise for the future may lie in tentative therapeutic approaches with [I-131]MIBG used at the time of diagnosis. The toxicity of [I-131]MIBG de novo contrasted with previous experience in [I-131]MIBG therapy in pretreated patients with relapses, since bone marrow depression did not appear to be very significant. We have recently investigated a new therapeutic approach to stage IV NB using a combination of [I-131]MIBG and cisplatin. Our results, although preliminary, suggest that this combined therapy is most effective in pretreated stage IV NB. However, relatively severe and long-lasting hematologic toxicity has been observed. We are at present trying to reduce the possible toxic synergism between cisplatin and [I-131]MIBG. Th, real therapeutic potential of radioiodinated MIBG in patients with NE has not yet fully explored. Future improvements may result from the contribution of further clinical and research investigations.