Head and neck cancer cells are efficiently infected by Ad5/35 hybrid virus.

Clinical gene therapy trials using standard Ad5-based vectors have thus far demonstrated limited efficacy, most likely due to low expression levels of adenoviral receptors on tumor cells. We sought to analyze adenoviral receptor expression levels on primary head and neck squamous cell carcinoma (HNSCC) cells and to determine whether adenoviral retargeting to the CD46 receptor via the Ad5/35 system would increase therapeutic potential for HNSCC. We used flow cytometric analyses to determine adenoviral receptor expression levels on nine primary HNSCC cells collected from cancer patients. Adenoviruses Ad5.LacZ and Ad5/35.LacZ were used to analyze the differences in viral transduction both in vitro and in a HNSCC tumor mouse model. Flow cytometric analyses demonstrated uniformly high CD46 expression in all cells studied (85-99%). In contrast, coxsackievirus and adenovirus receptor (CAR) expression was substantially lower and highly variable (1.6-62%). Alpha(v) integrin expression was between 39-98%. In situ stainings for beta-galactosidase gene expression demonstrated that Ad5/35.LacZ was clearly more effective than Ad5.LacZ in transducing primary HNSCC cells. Quantification of beta-galactosidase expression revealed up to 65 times higher transgene expression from Ad5/35.LacZ than Ad5.LacZ. In vivo, beta-galactosidase expression was detected in a substantial area after a single intratumoral injection of Ad5/35.LacZ, whereas injection with Ad5.LacZ resulted in gene expression only in a few cells. Our results demonstrate that the low and variable CAR expression levels limit the therapeutic efficacy of Ad5-based strategies for HNSCC. In contrast, the effective in vivo transduction capacity of Ad5/35 warrants further development of this vector for the treatment of head and neck cancer.

Suominen E ，Toivonen R ，Grenman R ，Savontaus M ... -  《JOURNAL OF GENE MEDICINE》

Variability of adenovirus receptor density influences gene transfer efficiency and therapeutic response in head and neck cancer.

Li D ，Duan L ，Freimuth P ，O'Malley BW Jr ... -  《CLINICAL CANCER RESEARCH》

Retargeting improves the efficacy of a telomerase-dependent oncolytic adenovirus for head and neck cancer.

Toivonen R ，Suominen E ，Grenman R ，Savontaus M ... -  《ONCOLOGY REPORTS》

Novel adenoviral gene delivery system targeted against head and neck cancer.

Li D ，Guang W ，Abuzeid WM ，Roy S ，Gao GP ，Sauk JJ ，O'Malley BW Jr ... -  《LARYNGOSCOPE》

Fiber-knob modifications enhance adenoviral tropism and gene transfer in malignant glioma.

Malignant gliomas remain refractory to Ad5-mediated gene therapy due to deficiency of the coxsackie adenovirus receptor on tumor cells. The purpose of this study was to evaluate whether changes in adenoviral tropism can enhance gene transfer in the context of malignant glioma. We have identified several receptors that are over-expressed on tumor cells and created a series of pseudotyped Ad5 vectors that recognize these receptors: Ad5-RGD which binds alpha(v)beta3/alpha(v)beta5 integrins; Ad5/3 which contains adenovirus serotype 3 knob and binds to CD46; Ad5-Sigma which incorporates the reovirus sigma knob and binds to junctional adhesion molecule-1; and Ad5-pk7 which contains the polylysine motif and binds heparan sulfate proteoglycans. We also investigated the Ad5-CAV1 vector, which contains the knob of canine adenovirus type 1, a virus previously shown to infect glioma via an unknown mechanism. In this study, we compared these modified vectors for their ability to promote the expression of luciferase transgene both in vitro and in vivo. Our results indicate that all five modified vectors attained higher mean luciferase activity vs. control. Among them, Ad5-CAV1 and Ad5-pk7 attained the highest transduction efficiency independent of different tumor lines or infection time. Ad5-Sigma and Ad5-pk7 also demonstrated the least nonspecific infection in normal human astrocytes. Most importantly, Ad5-pk7 achieved 1000-fold increased transgene expression in human glioma xenografts in vivo. These results indicate that modifications of adenoviral tropism can enhance gene transfer in tumors that are poorly susceptible to adenoviral vectors and warrant further development of Ad5-pk7 for glioma gene therapy.

Zheng S ，Ulasov IV ，Han Y ，Tyler MA ，Zhu ZB ，Lesniak MS ... -  《JOURNAL OF GENE MEDICINE》