Radiotheranostic Agents Targeting Neuroblastoma: State-of-the-Art and Emerging Perspectives

Abstract

Neuroblastoma (NB) represents the most common extracranial tumor of childhood. Prognosis is quite variable, ranging from spontaneous regression to aggressive behavior with wide metastatization, high mortality, and limited therapeutic options. Radiotheranostics combines a radiopharmaceutical pair in a unique approach, suitable both for diagnosis and therapy. For many years, metaiodobenzylguanidine (MIBG), labeled with 123I for imaging or 131I for therapy, has represented the main theranostic agent in NB, since up to 90% of NB incorporates the aforementioned radiopharmaceutical. In recent years, novel theranostic agents hold promise in moving the field of NB radiotheranostics forward. In particular, SarTATE, consisting of octreotate targeting somatostatin receptors, has been applied with encouraging results, with 64Cu-SARTATE being used for disease detection and with 67Cu-SARTATE being used for therapy. Furthermore, recent evidence has highlighted the potential of targeted alpha therapy (TAT) for treating cancer by virtue of alpha particles’ high ionizing density and high probability of killing cells along their track. On this path, 211At-astatobenzylguanidine (MABG) has been developed as a potential agent for TAT and is actually under evaluation in preclinical NB models. In this review, we performed a web-based and desktop literature research concerning radiotheranostic approaches in NB, covering both the radiopharmaceuticals already implemented in clinical practice (i.e.,123/1311-MIBG) and those still in a preliminary or preclinical phase.

Cancer Theranostics: Pharmaceutical View

“…123I-MIBG and 131I-MIBG are used in clinical imaging studies, more effective in stage IV neuroblastoma as they offer better visibility [29]. As the I-MIBG structurally resembles norepinephrine, it is easily taken up by the neuroendocrine cells [16,17]. However, it must be brought to attention that acute thyroid blockade is necessary before I-MIBG use, as the iodine complex is most likely absorbed by the thyroid glands [30].…”