Oncolytic adenoviruses replicate and amplify themselves within tumour cells, mediating targeted cytotoxicity as well as allowing tumour-selective expression of encoded biologics such as cytokines or checkpoint inhibitor antibodies, for secretion into the tumour microenvironment. We have developed adenoviruses suitable for i.v. delivery to disseminated disease in humans, and are now ‘arming’ them to express bispecific T cell engagers (BiTEs) capable of activating endogenous T cells to attack endogenous tumour cells. This new generation of viruses can combine targeted cytotoxicity, local reversal of immune suppression and intratumoural activation of T cells to give a combined therapeutic effect that can be rapidly translated into the clinic.