High-dose I-metaiodobenzylguanidine therapy in patients with high-risk neuroblastoma in Japan.

The aim of the study was to investigate the outcomes and prognostic factors of high-dose I-metaiodobenzylguanidine (I-MIBG) therapy in patients with refractory or relapsed neuroblastoma (NBL) in Japan.We retrospectively analyzed 20 patients with refractory or relapsed high-risk NBL who underwent I-MIBG therapy with an administration dose ranging from 444 to 666 MBq/kg at Kanazawa University Hospital, Japan, between September 2008 and September 2013. We focused on measurements regarding their initial responses, prognostic factors, survivals, and toxicities following I-MIBG therapy using our hospital data and questionnaires from the hospitals that these patients were initially referred from. Furthermore, we performed Kaplan-Meier survival analysis to evaluate event-free survival (EFS) and overall survival (OS).In 19 patients with complete follow-up data, the median age at first I-MIBG treatment was 7.9 years (range 2.5-17.7 years). Following I-MIBG therapy, 17 of the 19 patients underwent stem-cell transplantations, and their treatment response was either complete (CR) or partial (PR) in three and two cases, respectively. The EFS and OS rates at 1 year following I-MIBG therapy were 42% and 58%, respectively, and those at 5 years following I-MIBG therapy were 16% and 42%, respectively. Using the two-sample log-rank test, the OS time following I-MIBG therapy was significantly longer for < 3-year time interval between the initial diagnosis and I-MIBG therapy (p = 0.017), Curie score < 16 just before I-MIBG therapy (p = 0.002), without pain (p = 0.002), without both vanillylmandelic acid (VMA) and homovanillic acid (HVA) elevation (p = 0.037) at I-MIBG therapy, and with CR or PR following I-MIBG therapy (p = 0.015). Although severe hematological toxicities were identified in all 19 patients, severe nonhematological toxicity was not recorded in any patient, except for one patient with grade 3 anorexia and nausea.High-dose I-MIBG therapy in patients with refractory or relapsed high-risk NBL can provide a favorable prognosis without severe nonhematological toxicities. Better prognosis may be anticipated in patients with the initial good response, no pain at I-MIBG therapy, no VMA and HVA elevation at I-MIBG therapy, low Curie score (< 16) just before I-MIBG therapy, and short time interval (< 3 years) between the initial diagnosis and I-MIBG therapy.