Investigating the oncolytic properties of a group B adenovirus on cancer cells and its effects on the local immune response

Oncolytic viruses are characterised by their ability to selectively infect and kill tumour cells. Recently it has emerged that they can exert an additional anticancer mechanism stimulating adaptive immune-mediated cancer cell killing. Enadenotucirev (EnAd, formerly known as ColoAd1), is a chimeric Ad11p/Ad3 virus group B oncolytic adenovirus that binds CD46 and is under development for the systemic treatment of metastatic carcinomas. The central aim of this thesis was to to assess whether EnAd provides an adjuvant effect on tumour-associated antigen presenting cells (APCs) that could drive TH1 polarisation for an effective anti-tumour immune response. This thesis describes the potent oncolytic properties, fast replication and high numbers of virus progeny production by EnAd in cancer cells. Recombinant EnAd variants were engineered to investigate the roles of the mutant regions in the genome of EnAd, and how these influence the modified phenotype. A chemical drug panel was used to identify pathways and cellular factors involved in cellular production of EnAd, finding that several mTOR inhibitors and microtubule inhibitors could improve virus replication. An ,em>in vitro system using partially matured human monocyte-derived dendritic cells (DCs), which displayed a similar phenotype to tumour-infiltrating DCs, was used to explore the effect of EnAd on APC responses. EnAd induced a strong adjuvant effect on these cells by up-regulating surface markers and secretion of pro-inflammatory factors. Further mechanistic experiments, alongside a CAR-binding group C adenovirus 5, indicated these adjuvant effects were virus particle-mediated and dependent on CD46 binding. To understand the functional implications downstream of these interactions, T cell activation and phenotype was assessed using a mixed lymphocyte reaction approach. The data indicated EnAd was a good candidate compared to other adenoviruses, that may steer the response of activated T-cells towards a TH1 phenotype, for an effective immune response. In conclusion, the potent oncolytic properties of EnAd virus may provide an adjuvant effect on tumour-associated APCs, helping to harness an adaptive immune response.