Iodine-131 metaiodobenzylguanidine (131I-mIBG) treatment in relapsed/refractory neuroblastoma

Background I-131-meta-iodo-benzylguanidine (I-131-mIBG) therapy has been used in treatment of for advanced neuroblastoma for many years with promising results. There are several studies regarding predictors and outcomes of I-131-mIBG therapies in relapsed/refractory neuroblastoma patients. Objective To identify the predictors and outcomes of I-131-mIBG treatment in relapsed/refractory neuroblastoma. Methods This study was a retrospective review of 22 patients with high risk stage IV relapsed/refractory neuroblastoma who received at least one cycle of I-131-mIBG therapy. Patient' characteristics, hematologic toxicity, scintigraphic semi-quantitative scoring, and overall survival were recorded. Factors predicting survival were analyzed. Results Twenty-two patients (50% male) with mean age of 3.7 years (4.8 months to 8.3 years) received I-131-mIBG therapies at an average of 3.8 and mean dose of 136 mCi (5032 MBq) per treatment. Most common acute hematologic toxicity was thrombocytopenia. Overall 5-year survival rate was 37% (95% confidence interval: 16.3-58.0) and median survival time was 2.8 year (95% confidence interval: 1.38-6.34). Patients with rising Curie score of >= 25% upon the second therapy were major determinants of overall survival with poorer response to treatment. At least three treatments of I-131-mIBG were needed to identify some degrees of survival prolongation (crude hazard ratio: P-value = 0.003). Age, sex, metastatic status, and baseline Curie scoring system were good predictors associated with survival. Seven patients (32%) demonstrated objective responses. Conclusion Despite multimodality therapy, high risk neuroblastoma had a propensity of treatment failure in terms of relapsed or refractory, with some objective responses after I-131-mIBG treatments. The declined or non-rising Curie score upon second post-treatment total body scan was an important predictor of survival and aided a decision whether or not to proceed with bone marrow transplantation.