Natural TCRs targeting KRASG12V display fine specificity and sensitivity to human solid tumors
Adham S. Bear, … , Gerald P. Linette, Beatriz M. Carreno
Adham S. Bear, … , Gerald P. Linette, Beatriz M. Carreno
Published September 17, 2024
Citation Information: J Clin Invest. 2024;134(21):e175790. https://doi.org/10.1172/JCI175790.
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Clinical Medicine Immunology Oncology

Natural TCRs targeting KRASG12V display fine specificity and sensitivity to human solid tumors

Abstract

BACKGROUND Neoantigens derived from KRASMUT have been described, but the fine antigen specificity of T cell responses directed against these epitopes is poorly understood. Here, we explore KRASMUT immunogenicity and the properties of 4 T cell receptors (TCRs) specific for KRASG12V restricted to the HLA-A3 superfamily of class I alleles.METHODS A phase 1 clinical vaccine trial targeting KRASMUT was conducted. TCRs targeting KRASG12V restricted to HLA-A*03:01 or HLA-A*11:01 were isolated from vaccinated patients or healthy individuals. A comprehensive analysis of TCR antigen specificity, affinity, crossreactivity, and CD8 coreceptor dependence was performed. TCR lytic activity was evaluated, and target antigen density was determined by quantitative immunopeptidomics.RESULTS Vaccination against KRASMUT resulted in the priming of CD8+ and CD4+ T cell responses. KRASG12V -specific natural (not affinity enhanced) TCRs exhibited exquisite specificity to mutated protein with no discernible reactivity against KRASWT. TCR-recognition motifs were determined and used to identify and exclude crossreactivity to noncognate peptides derived from the human proteome. Both HLA-A*03:01 and HLA-A*11:01–restricted TCR-redirected CD8+ T cells exhibited potent lytic activity against KRASG12V cancers, while only HLA-A*11:01–restricted TCR-T CD4+ T cells exhibited antitumor effector functions consistent with partial coreceptor dependence. All KRASG12V-specific TCRs displayed high sensitivity for antigen as demonstrated by their ability to eliminate tumor cell lines expressing low levels of peptide/HLA (4.4 to 242) complexes per cell.CONCLUSION This study identifies KRASG12V-specific TCRs with high therapeutic potential for the development of TCR-T cell therapies.TRIAL REGISTRATION ClinicalTrials.gov NCT03592888.FUNDING AACR SU2C/Lustgarten Foundation, Parker Institute for Cancer Immunotherapy, and NIH.

Authors

Adham S. Bear, Rebecca B. Nadler, Mark H. O’Hara, Kelsey L. Stanton, Chong Xu, Robert J. Saporito, Andrew J. Rech, Miren L. Baroja, Tatiana Blanchard, Maxwell H. Elliott, Michael J. Ford, Richard Jones, Shivang Patel, Andrea Brennan, Zachary O’Neil, Daniel J. Powell Jr., Robert H. Vonderheide, Gerald P. Linette, Beatriz M. Carreno

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Figure 2

TCRs are specific for KRASG12V and exhibit distinct peptide-binding motifs with crossreactivity to KRASG12C.

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TCRs are specific for KRASG12V and exhibit distinct peptide-binding moti...
(A) FACS profiles of TCR-engineered JASP90_CD8+ cells following 16 hours of coculture with HLA-I –matched K562 cells pulsed with KRASWT (black) or cognate KRASG12V (colored) peptide. (B) Bar graphs representing NFAT activation (specific activity, %) of JASP90_CD8+ cells following 16 hours of coculture with HLA-I–matched K562 cells pulsed with 9-mer and 10-mer KRASWT or KRASG12V peptides. (C) Peptide-binding motifs determined by X-scan analysis of TCR A3V, A11Va, A11Vb, and A11Vc depicted as heatmaps (top) and Seq2Logo plots (bottom) using JASP90_CD8+ reporter cells cocultured with HLA-I–matched K562 cells pulsed with positional peptide scanning library peptides. Heatmaps: specific activity = (GFPExp - GFPMin) / (GFPMax – GFPMin); GFPMin = unstimulated, GFPMax = PMA-I. Seq2Logo plots: height of amino acid at each position corresponds to EGFP expression relative to unstimulated and PMA-I conditions. (D) Cell-reporter assay using TCR-engineered JASP90_CD8+ cocultured with K562A*11:01 cells pulsed with titrated levels of cognate G12V versus G12C peptides. Differences in TCR functional avidities for each peptide are displayed as Δlog10(EC50) values. Data are representative of 2 or more experiments.