Reprogramming the Tumor Microenvironment via Intratumoral Expression of Influenza Virus-Derived Peptides to Enhance Anti-Tumor Immune Responses

Solid tumors often exhibit an immunologically "cold" microenvironment with low cytotoxic T cell infiltration, limiting the efficacy of current immunotherapies. In this study, we investigated whether virus-specific CD8+ T cells can be redirected to tumors through local expression of an influenza A virus-derived peptide (NP147-155), independent of tumor antigens. Using syngeneic murine models (4T1 and CT26), we delivered NP147-155 via intratumoral peptide injection or lentiviral transduction. Transcriptomic profiling (RNA-seq), flow cytometry, and functional assays were performed to assess immune activation and tumor control. We found that expression of the viral peptide in the tumor microenvironment activated virus-specific memory CD8+ T cells, increased interferon-gamma production, and promoted T cell infiltration, effectively converting "cold" tumors into "hot" tumors. The antitumor effects were independent of MHC class I and mediated through the NKG2D-NKG2DL axis. These findings suggest a tumor-agnostic immunotherapy strategy leveraging pre-existing antiviral immunity to remodel the tumor immune landscape.