Radiolabeled metaiodobenzylguanidine for imaging and therapy of neuroblastoma

Neuroblastoma is an embryonic tumor of the peripheral sympathetic nervous system, and is able to take up, store and secrete catecholamine metabolites. Neuro-blastoma is metastatic or otherwise high risk for relapse in nearly 50% of cases, with a long-term survival of <40%, necessitating new approaches to therapy. The tumor cells express the norepinephrine transporter, which makes metaiodobenzylguanidine (MIBG), an analogue of norepinephrine, an ideal tumor specific agent for imaging and therapy, when labeled with (123)I or (131)I. This article will briefly review the use of [(123)I]MIBG imaging for monitoring therapy in neuroblastoma, and concentrate on the past, current and planned clinical trials using [(131)I]MIBG as targeted radiotherapy. The administration guidelines, toxicity, response and survival are discussed. Various therapeutic approaches include MIBG monotherapy, sequential infusion, and combination therapy. Treatment with MIBG has been tested as induction therapy, part of consolidation, and as treatment for relapse. The high response rates of 30-40% using MIBG monotherapy in relapsed neuroblastoma, and the low non-hematologic toxicity make this an ideal agent for incorporation into standard therapy of high-risk neuroblastoma.