Figure 1 Mechanisms of oncolytic-virus-based cancer therapy Figure 1 | Mechanisms of oncolytic-virus-based cancer therapy. Oncolytic viruses trigger three distinct but interrelated mechanisms that damage tumours: direct oncolysis, vascular collapse, and antitumour immunity. These viruses preferentially infect and kill cancer cells (oncolysis). Progeny virus released during oncolysis spreads to neighbouring cancer cells, amplifying the oncolytic effect. In addition, oncolytic viruses also target cells of the tumour stroma and promote neutrophil-dependent microclots within blood vessels, leading to the collapse of tumour vasculature, which hampers proliferation and promotes apoptosis of tumour cells. Finally, oncolytic viruses promote the activation of innate and adaptive immune responses against the tumour, establishing an otherwise lacking antitumour immune response. Virus infection of the tumour induces strong pro-inflammatory reactions that drive the recruitment of immune cells, including natural killer (NK) cells, T cells, dendritic cells (DCs), and macrophages, to the tumour microenvironment. Contact with oncolytic viruses or oncolytic-virus-induced cytokines can drive the direct activation of immune cells. In addition, antigen-presenting cells capture fragments of lysed tumour cells, migrate to lymph nodes, and initiate the priming of antitumour CD4+ and CD8+ T cells. These activated T cells destroy local and metastatic tumour cells in an antigen-specific manner. This three-pronged attack by oncolytic viruses can induce clinically desired therapeutic effects on prostate cancer. Lee, P. & Gujar, S. (2018) Potentiating prostate cancer immunotherapy with oncolytic viruses Nat. Rev. Urol. doi:10.1038/nrurol.2018.10