Mechanism and Therapeutic Potential of Viral Mimicry in Cancer Immunotherapy.

Cancer immunotherapy has transformed oncology by harnessing the immune system to recognize and eliminate malignant cells. However, many cancers exhibit limited or variable responses to this class of treatment due to insufficient antigen presentation and impaired interferon (IFN) signaling, creating an immunologically "cold" tumor microenvironment (TME) characterized by poor immune cell infiltration and treatment resistance. Viral mimicry has emerged as a therapeutic strategy to overcome these limitations by reactivating innate antiviral pathways within tumor cells. Viral mimicry occurs through the reactivation of endogenous retroviruses (ERVs) and other retrotransposons (e.g., LINE-1), which subsequently stimulate downstream nucleic acid sensing pathways. The resulting type I/III IFN responses restore antigen presentation and attract cytotoxic immune cells, sensitizing resistant tumors to immunotherapy. However, systemic stimulation of these pathways can trigger context-dependent inflammation and adaptive resistance, highlighting the need for temporal and spatial control. In this review, we examine the mechanistic foundation and clinical trajectory of viral mimicry, with an emphasis on its potential integration with established treatments and engineered immune cell platforms. By identifying the molecular and clinical gaps, viral mimicry can be harnessed to enhance tumor-specific immune activation and overcome treatment resistance in cancer immunotherapy.