Induction Regimen in High-Risk Neuroblastoma: A Pilot Study of Highly Effective Continuous Exposure of Tumor Cells to Radio-Chemotherapy Sequence for 1 Month. The Critical Role of Iodine-131-Metaiodobenzylguanidine.

The prognosis of high-risk neuroblastoma (NB) continues to be poor. The early development of resistance often leads to disease recurrence. In the present study, an innovative induction regimen, including an intensive initial radio-chemotherapy sequence based on the use of iodine-131-metaiodobenzylguanidine (131-I-MIBG), was investigated. The duration of the regimen lasted only one month. Fifteen newly diagnosed patients aged >18 months with high-risk NB were treated with cisplatin, etoposide, cyclophosphamide, and vincristine, followed on day 10 by 131-I-MIBG (dose: 12−18.3 mCi/kg). Cisplatin and vincristine were administered on day 20 and 21 followed by the re-administration of vincristine, cyclophosphamide, and doxorubicin on day 29 and 30. Non-hematologic toxicity was not observed. Moderate hematologic toxicity was present probably attributable to chemotherapy. The evaluation of response was performed approximately 50 days after the initiation of treatment, yielding four complete responses, eight very good partial responses, one partial response, and two non-responses. Importantly, a complete metastatic response was achieved in 87% of patients. The present pilot study, which includes 131-I-MIBG, allows for a highly effective continuous exposure of tumor cells to both chemotherapy and radiotherapy. Furthermore, early high-dose chemotherapy followed by stem cell rescue may achieve high levels of tumor cell clearance and improve the prognosis of high-risk NB.