Enhanced transduction of malignant glioma with a double targeted Ad5/3-RGD fiber-modified adenovirus

Malignant brain tumors remain refractory to adenovirus type 5 (Ad5)-based gene therapy, mostly due to the lack of the primary Ads receptor, the coxsackie and adenovirus receptor, on brain tumor cells. To bypass the dependence on coxsackie and adenovirus receptor for adenoviral entry and infectivity, we used a novel, double targeted Ads backbone-based vector carrying a chimeric Ads/3 fiber with integrin-binding RGD motif incorporated in its Ad3 knob domain. We then tested the new virus in vitro and in vivo in the setting of malignant glioma. Ads/3-RGD showed a 10-fold increase in gene expression in passaged cell lines and up to 75-fold increase in primary tumors obtained from patients relative to the control. These results were further corroborated in our in vivo human glioma xenograft model, where the Ads/3-RGD vector showed a 1,000-fold increase in infectivity as compared with the control. Taken together, our findings indicate that Ads/3-RGD may be a superior vector for applications in glioma gene therapy and therefore warrants further attention in the field of neuro-oncology.