Document Type

Article

Rights

This item is available under a Creative Commons License for non-commercial use only

Disciplines

1.6 BIOLOGICAL SCIENCES, Cell biology,, Biochemistry and molecular biology, Biochemical research methods, Gene-based diagnostics and therapeutic interventions, Gene based therapeutics

Publication Details

Clinical Cancer Research (Clin Cancer Res. 2009 Jul 1;15(13):4401-14)

Abstract

Purpose In preparation for a Phase I clinical trial utilizing a combined cytotoxic/immunotherapeutic strategy using adenoviruses expressing Flt3L (Ad-Flt3L) and thymidine kinase (Ad-TK) to treat glioblastoma (GBM), we tested the hypothesis that Ad-TK+GCV would be the optimal tumor killing agent in relation to efficacy and safety when compared to other pro-apoptotic approaches. Experimental Design and Results The efficacy and neurotoxicity of Ad-TK+GCV was compared with Ads encoding the pro-apoptotic cytokines (TNF-α, TRAIL, FasL), alone or in combination with Ad-Flt3L. In rats bearing small GBMs (day 4), only Ad-TK+GCV or Ad-FasL improved survival. In rats bearing large GBMs (day 9), the combination of Ad-Flt3L with Ad-FasL did not improve survival over FasL alone, while Ad-Flt3L combined with Ad-TK+GCV led to 70% long-term survival. Expression of FasL and TRAIL caused severe neuropathology, which was not encountered when we utilized Ad-TK+/−Ad-Flt3L. In vitro, all treatments elicited release HMGB1 from dying tumor cells. In vivo, the highest levels of circulating HMGB1 were observed after treatment with Ad-TK+GCV+Ad-Flt3L; HMGB1 was necessary for the therapeutic efficacy of AdTK+GCV+Ad-Flt3L, since its blockade with glycyrrhizin completely blocked tumor regression. We also demonstrated the killing efficacy of Ad-TK+GCV in human GBM cell lines and GBM primary cultures; which also elicited release of HMGB1. Conclusions Our results indicate that Ad-TK+GCV+Ad-Flt3L exhibits the highest efficacy and safety profile amongst the several pro-apoptotic approaches tested. The results reported further support the implementation of this combined approach in a Phase I clinical trial for GBM.

DOI

10.1158/1078-0432.CCR-09-0155

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