Enhanced gene transfer and oncolysis of head and neck cancer and melanoma cells by fiber chimeric oncolytic adenoviruses

Purpose: The purpose of this study was to evaluate a fiber knob replacement strategy to improve infectivity and efficacy of Ad5 fiber chimeric oncolytic viruses for treatment of melanoma and head and neck cancers (HNC). Experimental Design: Adenoviral receptors and transduction levels were used to determine the level of infectivity of fiber-modified, green fluorescent protein - expressing, replication - deficient viruses in a panel of melanoma and HNC cell lines in vitro. Virus yield and cytotoxicity assays were used to determine the tumor specificity and virus replication-mediated cytotoxicity of the fiber-modified oncolytic viruses in the same panel of melanoma and HNC in vitro. Xenograft tumor models were used to assess the antitumor activity of those fiber-modified chimeric viruses compared with the parental virus. Results: Marker gene expression following gene transfer of the fiber chimeric vectors in melanoma and HNC cell lines was similar to 10-fold higher than that obtained with parental Ad5 vector. The fiber chimeric oncolytic variants mediated killing of melanoma and HNC cells that was 2- to 576-fold better than with the parental virus. In addition, fiber chimeric variants produced 2- to 7-fold more progeny virus in tumor cells than the parental virus. Moreover, a high multiplicity of infection was needed for the fiber chimeric viruses to produce cytotoxicity in normal cells. A significantly stronger antitumor response and survival advantage were shown in the tested melanoma and HNC xenograft models following i.t. injections. Conclusions: In vitro and in vivo studies showed the improved transduction, replication, cytotoxicity, antitumor efficacy, and survival advantage in melanoma and HNC tumor models, suggesting a potential use of these oncolytic agents for the treatment of melanoma and HNCs.