A New Therapeutic Use of High -dose' 'I-MIBG Therapy as Consolidation Therapy in Pediatric Patients with High -risk Neuroblastoma: The Japanese experience.

624 Purpose: Pediatric high-risk neuroblastoma patients have poor prognoses despite modern multimodality therapy. Novel and more effective therapeutic strategies are required for high-risk neuroblastoma. We retrospectively examined the utility of consolidation therapy with high-dose 131I-meta-iodo-benzyl-guanidine (131I-MIBG) against invisible tumor cells on 123I-MIBG scintigraphy in pediatric patients with high-risk neuroblastoma and ganglioneuroblastoma. \nMaterials and Methods: From December 2009 to December 2014, there were nine high-risk pediatric neuroblastoma and one high-risk ganglioneuroblastoma pediatric patients with complete response to primary therapy in diagnostic 123I-MIBG scintigraphy. The nine who received high-dose 131I-MIBG therapy were included in this study. One pediatric patient who received lower-dose 131I-MIBG therapy (\u003c444 MBq/kg, due to law regulation) was excluded from this study. Some patients received bone marrow rescue after the 131I-MIBG therapy. Overall and event-free survivals at 4-years after the 131I-MIBG therapy of the nine pediatric patients were analyzed by the Kaplan-Meier method.\n Results: No patient had abnormal uptake on post-therapeutic 131I-MIBG scintigraphy. Six pediatric patients (67%) had no sign of relapse and three pediatric patients (33%) relapsed during the observed period. One non-relapse patient died for side effects of consolidation chemotherapy and 2 relapsed pediatric patients died due to tumor progression. The event-free and overall survival rate from 131I-MIBG therapy was 65% and 78% at 4 years, respectively. No life-threatening side effect of 131I-MIBG therapy except myelosuppression was observed. Conclusions: The consolidation therapy with high-dose 131I-MIBG had good overall and event-free survival in pediatric patients with high-risk neuroblastoma. While we must consider risks of radiation exposure and beta particle range, the high-dose 131I-MIBG therapy as consolidation therapy should be further investigated.