Abstract 16: CD4+ and CD8+ TCRαβ-deficient bioluminescent reporter T cells for screening and characterization of neoantigen-specific TCRs

Abstract

Abstract Adoptive antigen-specific T cell therapy is currently comprised of chimeric antigen receptor (CAR) and T cell receptor (TCR) engineered T cells. Clinical results from CAR-T cells have demonstrated promising results in treating leukemias, while TCR-engineered T cells, which have the advantage of recognizing intracellular tumor antigens, is still in early development. Here, we report the development of CD4+ or CD8+ TCRαβ-KO reporter T cell lines for the screening and characterization of transgenic TCRs. A TCRαβ-KO reporter T cell line was first developed by knocking out the endogenous TCR α and β chains in the reporter T cell line using CRISPR/Cas9. Successful knockout was confirmed by phenotypic assays and TCR v chain locus sequencing. We demonstrated that re-introduction of influenza hemagglutinin (HA) peptide-specific TCR (HA1.7) α and β chains into TCRαβ-KO reporter T cell lines results in HA peptide-dependent TCR activation and luciferase reporter expression when HA peptide is presented by a MHCII+ cell line. Similarly, re-introduction of MART-1-specific TCR (DMF5) resulted in MART-1-dependent activation in the presence of MHCI+ cells. The select expression of CD4- or CD8-expressing variants of the TCRαβ-KO reporter T cell line enables the development of transgenic TCRs for both MHCI- and MHCII-restricted tumor antigen targets. Further development of CD4/CD8 double-positive and double-negative cell lines enables screening of low and high affinity TCRs without MHC bias. Together, this TCRαβ-KO platform represents a powerful tool for the screening and characterization of neoantigen-specific TCRs. Citation Format: Mei Cong, Jamison Grailer, Michael Slater, Pete Stecha, Jim Hartnett. CD4+ and CD8+ TCRαβ-deficient bioluminescent reporter T cells for screening and characterization of neoantigen-specific TCRs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 16.