Abstract 295: Delivery of checkpoint inhibitor antibodies and other therapeutics directly to tumors by encoding them within the oncolytic adenovirus enadenotucirev

Abstract

Abstract We are developing “armed” versions of the oncolytic adenovirus, enadenotucirev (EnAd), that will selectively infect and deliver immunotherapeutics to tumours following systemic dosing. EnAd is a potent, chimeric Ad11p/Ad3 adenovirus active against a range of epithelial cancer cells. In normal cells, EnAd is attenuated and shows little or no activity by either cytotoxicity assay or qPCR. In vivo, EnAd shows efficacy in a range of xenograft human tumor models following intra-tumoural, intravenous and intra-peritoneal injection and is currently being evaluated clinically for treatment of several different epithelial cancers. Data from ongoing clinical studies have shown that i.v. dosed EnAd infects and selectively replicates in tumor cells, producing significant amounts of viral protein (hexon). This is associated with CD8 cell accumulation and also indicates that transgene encoded proteins will be made in significant amounts by tumors following i.v. delivery of an armed EnAd virus. To develop armed EnAd variants we have developed a novel, efficient cloning system for rapid generation of viruses that can produce antibodies and other payloads under the control of the virus replication cycle or exogenous promoters. As an initial exemplification of the platform we have successfully produced EnAd variants encoding full-length (NG-135) and ScFv (NG-76) forms of anti-human VEGF antibodies. These have similar virus activity profiles to EnAd in cancer cell lines in vitro (virus replication, gene expression and oncolytic action), but also express and release the respective anti-VEGF antibody forms into the culture supernatant of tumor cells but not non-transformed cells. Using HCT-116 or DLD human colon carcinoma xenograft models we have shown that the virus infection profile following intra-tumoral injection is also similar to the parental EnAd virus (virus replication and hexon gene expression). Anti-VEGF antibody expression could be detected in the tumor tissue as both mRNA and functional antibody. Antibodies were detectable early (within 3 days of infection) and sustained over several weeks. Using an orthotopic A549 lung tumor model, NG-135 virus dosed i.v. following the development of tumors was able to decrease tumor burden by >90%. Viruses similarly expressing IgG1 or ScFv versions of anti-PDL1 and anti-CTLA4 checkpoint inhibitor antibodies have also been made and shown to produce functional antibodies that inhibit the respective receptor-ligand interactions in a range of in vitro assays, including upregulation of T-cell responses. In conclusion, our data show that EnAd can be modified to produce different antibody “payloads” following infection of human tumor cells in vitro and in vivo. Evaluation of the in vivo impact of these armed oncolytic viruses on the growth and microenvironment of tumors is now in progress. Citation Format: Brian R. Champion, Prithvi Kodialbail, Sam Illingworth, Nalini Rasiah, Daniel Cochrane, John Beadle, Kerry Fisher, Alice Brown. Delivery of checkpoint inhibitor antibodies and other therapeutics directly to tumors by encoding them within the oncolytic adenovirus enadenotucirev. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 295. doi:10.1158/1538-7445.AM2015-295