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 t umor. Since promising results are obtained with aggressive chemotherap y, it might be expected that even better results could be obtained fro m a high radiation dosage. But delivery of high radiation doses is lim ited by host intolerance. [I-131]Metaiodobeuzylguanidine ([I-131]MIBG) , a radioiodinated aralkylguanidine, is capable of competing with nore pinephrine for uptake into neuroadrenergic tissue and derived tumors. Targeted radiotherapy with elevated doses has been pioneered by severa l groups, as a high dose of radioactivity can be selectively delivered to tumor cells, with an acceptable systemic toxicity. We briefly revi ew here the latest research achievements and the progress that has bee n made with the use of this new treatment modality in patients with ad vanced 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 wit h relapses, since bone marrow depression did not appear to be very sig nificant. We have recently investigated a new therapeutic approach to stage IV NB using a combination of [I-131]MIBG and cisplatin. Our resu lts, although preliminary, suggest that this combined therapy is most effective in pretreated stage IV NB. However, relatively severe and lo ng-lasting hematologic toxicity has been observed. We are at present t rying to reduce the possible toxic synergism between cisplatin and [I- 131]MIBG. Th, real therapeutic potential of radioiodinated MIBG in pat ients with NE has not yet fully explored. Future improvements may resu lt from the contribution of further clinical and research investigatio ns.