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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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 1

mDC3/8-KRAS vaccination primes KRASMUT-specific T cell immunity in PAAD patients.

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mDC3/8-KRAS vaccination primes KRASMUT-specific T cell immunity in PAAD ...
(A) Trial design. (B) Consolidated standards of reporting trials diagram. (C) Number of vaccine KRASMUT neoantigens per patient that induced IFN-γ+ T cells in ex vivo–expanded PBMCs collected after vaccine priming. (D) Normalized IFN-γ+ ELISpot counts for vaccine KRASMUT neoantigens after priming detected in ex vivo–expanded PBMCs. Spot counts of the nonstimulated controls were subtracted. Responses to short peptides (HLA-I) are indicated in red, and responses to long peptides (HLA-II) are indicated in blue. Symbol shape indicates specific KRASMUT as per legend. (E) Assessment of subject no. 2 HLA-I–restricted T cell responses against 8–16V (blue) and 7–16V (red) peptides by IFN-γ ELISpot assay following ex vivo expansion of week 2 postvaccine PBMCs. Free peptide supplemented to media bound by HLA-I expressed on donor white blood cells (HLA-A*11:01 and -A*03:01) and presented to responding T cells. Monoallelic K562 cells expressing HLA-A*03:01 (APC-A3) or HLA-A*11:01 (APC-A11) were used to identify HLA-I restriction. WT indicates WT KRAS peptide. MUT indicates mutant KRAS peptide. (F) pHLA multimer analysis to assess CD8+ T cell response against 8–16V/A*11:01 and 7–16V/A*11:01 following in vitro expansion of pre- (week –1) and postvaccine (week 10) CD8+ T cells. Successful priming of CD8+ T cell responses to gp10017–25/A*03:01 and NY-ESO60–72/B*07:02 served as positive vaccination controls. (G) Circos plot analysis following TCR-αβ RNA sequencing of FACS-sorted CD8+/multimer+ (8–16V/A*11:01) cells. Statistical differences between groups calculated using Students’ unpaired t test.