Abstract C020: Identification of KRAS-specific TCRs from human peripheral blood

Abstract Mutant KRAS is the predominant driver oncogene in pancreatic cancer accounting for approximately 90% of KRAS mutations. However, these mutant KRAS peptides exhibit weak binding affinity to most human leukocyte antigens (HLAs), impeding their recognition by the immune system and the subsequent generation of a corresponding T cell response. Identification of KRAS-mutant specific T cells would be useful to track tumor-specific T cell responses in patients and could also be used for adoptive transfer of TCR-transduced cells. Current efforts to identify KRAS-specific T cells have been limited by their restriction to specific HLA haplotypes or the provision of only a few T cell receptor (TCR) sequences. In this study, we developed a facile means of detecting KRAS-specific T cells from peripheral blood at frequencies as low as 1 in 1, 000, 000. We employ an α41BB agonist-selective lentivirus system combined with a KRAS peptide pool to facilitate the high-throughput discovery of KRAS-specific TCRs in peripheral blood mononuclear cells (PBMCs) derived from both patients with pancreatic cancer and healthy donors. Through in vitro stimulation and single-cell TCR analysis, we identified a series of T cell expansions sharing the same clonotype, indicating a response to KRAS-mutant peptide stimulation. We have quantified CD4 and CD8 KRAS-specific TCRs from patients with a diverse range of HLA haplotypes. Citation Format: Jiao Shen, Blake E. Smith, Winiffer Conce Alberto, Ellen J. Kim, Michael L. Dougan, Harshabad Singh, Michael E. Birnbaum, Stephanie K. Dougan. Identification of KRAS-specific TCRs from human peripheral blood abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84 (17 Suppl₂): Abstract nr C020.