TCR targeting of KRAS G12V/C neoantigens is enhanced by lymphodepleting chemotherapy

Lung cancer remains the leading cause of cancer-related deaths worldwide. Immunotherapy agents have doubled treatment response rates in non-small cell lung cancer (NSCLC). However, these responses are neither universal nor consistently durable, underscoring the need for innovative therapeutic strategies. Using a data-driven approach, we identified and characterized an immunogenic neopeptide derived from the KRAS.G12V mutation, prevalent in lung, colon, and pancreatic cancers. We isolated a cognate TCR, T104, which targets and kills cancer cells expressing KRAS G12V. Moreover, TCR-T104 proved to cross-react with the KRAS.G12C neoantigen via a hydrophobic pocket and kill cancer cells expressing this prevalent KRAS mutant. Combining TCR therapy with lymphodepleting chemotherapy using fludarabine and cyclophosphamide resulted in synergistic antitumor effects against multiple neoantigens. HLA-immunopeptidomics revealed that chemotherapy modulates the cell immunopeptidome and enhances target peptide presentation, likely through immunoproteasome activation and HLA-I elevation. These findings suggest a new mechanism explaining the combined efficacy of chemotherapy and immunotherapy.