Beyond cold to hot: oncolytic virotherapy as the next cornerstone of immuno-oncology.

Oncolytic virotherapy has evolved from a platform predicated on lysis of cancer cells into a sophisticated system for intratumoural immune reprogramming; the prevailing 'cold-to-hot' paradigm captures only part of this potential. A fundamental limitation shared by immune checkpoint inhibitors (ICIs) and early-generation oncolytic viruses (OVs) is a reliance on pre-existing tumour-specific T cells (TSTs), which presents an immunological ceiling that constrains antitumour activity - given that these agents have a limited capacity to generate TSTs de novo. Next-generation OVs overcome this constraint by functioning as agents for antigen-agnostic in situ cancer vaccination: intratumoural infection triggers immunogenic cell death, releasing potentially the full cancer proteome under pathogen-associated and/or damage-associated molecular pattern adjuvant conditions, thereby driving T cell priming against patient-specific neoantigens. In this Perspective, we delineate four pillars for the development of next-generation OVs. First, intratumoural vaccination as immunological ignition, with initial clinical data demonstrating T cell clonotype broadening, abscopal tumour regression and survival benefit in patients with ICI-refractory disease. Second, optimized payload-driven immune priming to hyperactivate antigen-presenting cells. Third, revised efficacy evaluation and end points using response criteria as well as novel biological correlates that better capture delayed and abscopal immune-mediated tumour control. Fourth, OV as the foundational immuno-oncology platform: according to the 'triple-A' framework encompassing admission, availability and activation of TSTs, next-generation, payload-engineered OVs uniquely satisfy all prerequisites for antitumour immunity simultaneously, with evidence from clinical trials of such agents supporting an 'OV-prime, ICI-amplify' strategy. Notably, OVs are systemic immune-reprogramming platforms that are delivered locally, not local therapies with incidental systemic effects.