Oncolytic Virotherapy and Immunogenic Cell Death: Mechanisms, Platforms, and Clinical Translation.

Oncolytic viruses represent a paradigm-shifting approach to cancer immunotherapy, functioning as in situ vaccines that convert immunologically "cold" tumors into "hot" tumors through induction of immunogenic cell death (ICD). Despite the clinical success of checkpoint inhibitors targeting programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), many patients exhibit primary or acquired resistance due to insufficient tumor immunogenicity and exclusion of tumor-infiltrating lymphocytes. Oncolytic viruses address this limitation by selectively replicating in tumor cells, inducing robust ICD characterized by four cardinal hallmarks: calreticulin exposure, ATP secretion, HMGB1 release, and type I interferon production. This review systematically examines the molecular mechanisms underlying virus-induced ICD, compares DNA virus platforms (Vaccinia, HSV-1, Adenovirus) with RNA virus platforms (Coxsackieviruses A21, A11, and B3), and analyzes clinical trial data demonstrating synergistic efficacy when combined with checkpoint inhibitors. Notably, RNA viruses generate higher type I interferon responses compared to DNA viruses, correlating with superior clinical outcomes. Coxsackievirus A21 combined with pembrolizumab achieved a 47% objective response rate in melanoma in the CAPRA trial, representing notable efficacy exceeding either monotherapy. Coxsackievirus A11 demonstrates exceptional selectivity for thoracic cancers through ICAM-1-dependent receptor tropism and potent immunogenic cell death induction. Japanese researchers have pioneered microRNA-targeted Coxsackievirus B3, achieving cardiac safety attenuation while preserving complete oncolytic potency and ICD-inducing capacity. This comprehensive analysis synthesizes molecular mechanisms, platform comparisons, clinical efficacy data, and translational challenges to guide future development of oncolytic virotherapy as a cornerstone of cancer immunotherapy.