Abstract
Glioblastoma (GBM) is the most prevalent and lethal primary malignant brain tumor in adults. Oncolytic viruses have emerged as a promising immunotherapy to treat GBM. However, the temporal impact on tumor cells and the tumor microenvironment, and the nature of sustained anti-tumor immunity post-therapy remain largely unclear. We have recently identified CD4(+) T-cells as the critical cellular component that is responsible for oncolytic herpes simplex virus (oHSV)-mediated durable control of tumor in syngeneic immunocompetent murine models of GBM. oHSV treatment upregulates MHCII on residual tumor cells that is important for programmed polyfunctional CD4(+) T-cells to control tumor and to form memory responses. Single-cell RNA sequencing analysis further revealed that oHSV treatment expanded a subset of CD4(+) T-cells that displayed a unique signature and had distinct expanded T-cell receptor clonotypes. Flow cytometry analysis confirmed its kinetic expansion after treatment. Importantly, adoptive transfer of this subset prolonged survival in mice bearing GBM. In addition, spatial transcriptomics analysis of human GBM tissues collected from tumor infiltrative regions pointed a close localization relationship of this CD4(+) T-cell subset with dendritic cells (DC) in the non-malignant areas. CellChat analysis also showed that the interactions of DC and this subset were increased in oHSV-treated mice compared to vehicle controls. In sum, this CD4(+) T-cell subset, characterized by specific spatiotemporal regulation, may serve as a new prognostic biomarker for GBM patients and a response predictor for GBM patients receiving oHSV therapy, suggesting strategies to improve oHSV therapeutic efficacy and to develop new modalities to improve outcomes for patients with GBM.