A gene therapy approach to enhance the targeted radiotherapy of neuroblastoma.

Background: The aims of this study were to determine whether the introduction and expression of the noradrenaline transporter (NAT) gene into NAT-negative neuroblastoma cell lines would make them amenable to targeted radiotherapy using [(131)I]MIBG.

Procedure: Neuroblastoma cell lines were transfected with a eukaryotic expression vector containing the bovine noradrenaline transporter cDNA under the expression of the CMV promoter. Stable transfectants were created by selection in geneticin (G418) and were characterised for their MIBG uptake ability and susceptibility to [(131)I]MIBG therapy.

Results: The cell line SK-N-MC, which normally shows no ability to take up MIBG, was successfully transfected with bNAT. SK-N-MC.bNAT transfectants exhibited uptake and release kinetics similar to those of the natural NAT-expressing cell line SK-N-BE(2c). Levels of [(131)I]MIBG uptake were 33% of those of the highest naturally NAT-expressing cell line SK-N-BE(2c). Growth delay assays using multicellular spheroids indicated that this degree of [(131)I]MIBG uptake was sufficient to inhibit growth at radioactive concentrations of 4 Mbq/ml.

Conclusions: These results demonstrate the feasibility of combining gene therapy with targeted radiotherapy to enhance uptake, and hence radiation dose, to neuroblastoma tumours using [(131)I]MIBG. With the appropriate delivery vehicle and tumour-specific control of expression, the introduction of noradrenaline transporter molecules may be a viable means of enhancing the response of neuroblastoma tumours to [(131)I]MIBG therapy.