Integrating oncolytic viruses in combination cancer immunotherapy

Oncolytic viruses can be usefully integrated into tumour immunotherapies, as they target multiple steps within the cancer–immunity cycle. Oncolytic viruses directly lyse tumour cells, leading to the release of soluble antigens, danger signals and type I interferons, which drive antitumour immunity. In addition, some oncolytic viruses can be engineered to express therapeutic genes or can functionally alter tumour-associated endothelial cells, further enhancing T cell recruitment into immune-excluded or immune-deserted tumour microenvironments. Oncolytic viruses can also utilize established tumours as an in situ source of neoantigen vaccination through cross-presentation, resulting in regression of distant, uninfected tumours. These features make oncolytic viruses attractive agents for combination strategies to optimize cancer immunotherapy. Oncolytic viruses can target multiple steps in the cancer–immunity cycle and can be engineered to express therapeutic genes and, as a result, can be usefully integrated in combination tumour immunotherapies. Here, the authors discuss features of oncolytic viruses that make them appealing agents for combination approaches in cancer immunotherapy.