Nuclear medicine therapy of neuroblastoma.

Specific targeting of radionuclides to neuroblastoma, a neural crest tumour occurring predominantly in young children and associated with a relatively poor prognosis, may be achieved via the metabolic route (MIBG), receptor binding (peptides) or immunological approach (antibodies). The clinical role of 131I-MIBG therapy and radioimmunotherapy in neuroblastoma is discussed. In recurrent or progressive metastatic disease after conventional treatment modalities have failed, 131I-MIBG therapy, with an overall objective response rate of 35%, is probably the best palliative treatment, as the invasiveness and toxicity of this therapy compare favourably with that of chemotherapy, immunotherapy and external beam radiotherapy. In patients presenting with inoperable stage III and IV neuroblastoma, 131I-MIBG therapy at diagnosis is at least as effective as combination chemotherapy but is associated with much less toxicity. In patients with recurrent disease 131I-MIBG therapy in combination with hyperbaric oxygen therapy proved feasible and encouraging effects on survival have been observed. Attempts to intensify the treatment in relapsed patients by combination of 131I-MIBG therapy with high dose chemotherapy and/or total body irradiation have met with considerable toxicity. Developments in MIBG therapy aiming at improving the therapeutic index are mentioned. Early results of radioimmunotherapy using 131I-UJ13A or 131I-3F8 monoclonal antibodies have shown moderate objective response and considerable side effects in patients with stage IV neuroblastoma, who had relapsed or failed conventional therapy. New developments in radioimmunotherapy of neuroblastoma include the use of chimaeric antibodies, the enhancement of tumour uptake by modulation of antigen expression or by increasing the tumour perfusion/vascularity/permeability, the use of other labels and multistep targeting techniques, e.g. using bispecific monoclonal antibodies.