In this first preclinical study, synthetic polymeric vectors based on pseudodendritic oligoamines were used for tumor-specific delivery of the sodium iodide symporter (NIS) gene after systemic delivery, resulting in a significant therapeutic effect of radioiodine in a neuroblastoma mouse model. The figure shows immunofluorescence analysis using a Ki67-specific antibody (green) and an antibody against CD31 (red, labeling blood vessels) revealing high proliferation and blood vessel density in control tumors in contrast to NIS-transduced tumors after radioiodine treatment. For further details, please see Klutz and coworkers 6079 in this issue.