High-dose ¹³¹I-metaiodobenzylguanidine therapy in relapsed high-risk neuroblastoma: a descriptive analysis of clinical outcomes and associated factors

Relapsed high-risk neuroblastoma has poor prognosis despite aggressive salvage therapies. This study retrospectively examined 37 consecutive relapsed patients treated with high-dose ¹³¹I-metaiodobenzylguanidine (mIBG) to explore clinical and treatment-related factors associated with overall survival (OS). The patients received high-dose 131I-mIBG (≥ 444 MBq/kg) between September 2009 and December 2019. The prognostic factors analysed were as follows: relapse order (second or third vs. first), age, lesion type at 131I-mIBG therapy, Curie score (> 2 vs. ≤2), SIOPEN (> 2 vs. ≤2), presence of pain, prior allogeneic haematopoietic stem cell transplantation (HSCT), prior external-beam radiotherapy (EBRT), MYCN status and tumour response (complete remission [CR] vs. non-CR). OS was estimated using Kaplan–Meier analysis, with significance determined by log-rank tests and Cox regression. Of the 37 patients, 24 died during follow-up. Among the 36 evaluable patients, the 5-year OS rate from the 131I-mIBG infusion was 41% ± 8%. In the univariable analysis, second or subsequent relapse, a Curie score > 2, a SIOPEN score > 2, pain at infusion, absence of prior EBRT, prior allogeneic HSCT, and failure to achieve CR were associated with poorer OS. The absence of pre-131I-mIBG EBRT and prior allogeneic HSCT remained significantly associated with inferior OS in the multivariable analysis. High-dose 131I-mIBG yielded a 5-year OS of 41% in relapsed high-risk neuroblastoma. Lack of pre-131I-mIBG EBRT and previous allogeneic HSCT were independent indicators of poor prognosis. Early incorporation of 131I-mIBG and strategic patient selection may improve outcomes. Prospective studies with molecular profiling are warranted.