Evaluation of drug delivery vehicles for improved transduction of oncolytic adenoviruses in solid tumor tissue.

BACKGROUND: Oncolytic viruses are promising tools for immune stimulatory gene therapy of cancer, but their clinical effect on solid tumors have so far been limited. Transduction of the target tumor cells is limited by both extracellular matrix that blocks viral spread within the solid tumor tissue and electrostatic forces that inhibit virus from binding its entry receptor on the cell surface. The enzymes hyaluronidase and collagenase and the polycations diethylaminoethyl (DEAE)-dextran, branched Polyethylenimine (PEI) and protamine sulfate have previously shown potential to improve gene transfer in different forms of viral gene therapy, since they may help the virus to overcome these barriers. In this study, we compared the transduction-enhancing potential of these substances when used as vehicles for adenoviral transduction in solid tumor tissue. METHODS: Subcutaneous tumors of pancreatic ductal adenocarcinoma were established in mice and treated with a mix of adenoviral vector Adf35(GFP-Luc) and either one of the selected vehicles. Transduction efficacy was determined by quantification of the viral transgene expression level using live imaging. RESULTS: Addition of hyaluronidase tripled the transgene expression of Adf35(GFP-Luc) when compared to virus alone. No such positive effect was seen for the other tested vehicles. CONCLUSIONS: Out of the tested candidates, hyaluronidase showed the best potential to facilitate viral spread in tumor tissue and transduction of tumor cells. Therefore, hyaluronidase may be used as vehicle to improve clinical efficacy of oncolytic virotherapies.