Oncolytic zika virus therapy leverages CCR2+ monocytes to boost anti-glioblastoma T cell responses

BACKGROUND: Glioblastoma (GBM) is a lethal brain tumor with limited treatment options, largely due to profound immune suppression within the tumor microenvironment (TME), the failure of current immunotherapies to restore CD8+ T cell function, and persistence of glioma stem cells (GSCs) after treatment. Oncolytic Zika virus (ZIKV) is a promising therapeutic that selectively targets GSCs and remodels the TME to enhance anti-tumor CD8+ T cell responses. In this study we investigated how ZIKV efficacy in GBM is driven through monocytes. METHODS: We performed single-cell RNA sequencing and T cell receptor (TCR) sequencing to evaluate CD8+ T cell responses following ZIKV treatment. We used CellChat to define signaling networks between ZIKV-activated CCR2+ monocytes and CD8+ T cells in the TME. We used syngeneic, immunocompetent murine GBM models to validate mechanisms in vivo, applying genetic and antibody-based approaches to impair CCR2+ monocyte trafficking and function. RESULTS: ZIKV induced clonal expansion of tumor-infiltrating CD8+ T cells enriched in granzyme B and perforin-1, with reduced expression of exhaustion markers. CCR2+ monocytes were essential for the recruitment, proliferation, and effector functions of anti-tumor CD8+ T cells in the TME. Disruption of monocyte trafficking or function impaired these responses, diminishing cytotoxic activity and T cell recruitment. CONCLUSIONS: ZIKV-driven activation and recruitment of CCR2+ monocytes supports robust anti-tumor CD8+ T cell responses by enhancing cytotoxicity and limiting exhaustion. These findings highlight the previously unappreciated therapeutic potential of modulating monocyte-T cell crosstalk to overcome immune suppression in GBM.