398 Functional characterization of a class I-restricted CD8+ T cell receptor specific for the stem cell transcription factor Sox2
Year: 2024
Type: conference-abstract
Abstract: Background As relapse is a substantial cause of morbidity and mortality for cancer patients, novel therapies targeting mechanisms of relapse are urgently needed. Sox2 (Sex- determining region-box2) is a stem cell transcription factor whose expression confers drug resistance, enhanced proliferation, and survival advantage to residual cancer cells in several hematological and solid malignancies. Prior studies have suggested that T-cell immunity against SOX2 is associated with better clinical outcomes in patients treated with immunotherapies. Nonetheless, direct evidence of SOX2-specific T cell lytic activity against tumor cells is lacking. Methods We employed in silico predictions and immunopeptidomics to identify candidate HLA class I restricted SOX2-derived epitopes. SOX2-specific TCR sequences were identified from patients with plasma cell dyscrasias enrolled on an IRB-approved clinical studies at the University of Pennsylvania. Transgenic expression of synthetic TCRs was attained via lentiviral transduction of reporter cell lines or gene-edited (TCRabnull) primary CD8+ T cells. Antigen affinity was assessed via limiting peptide dilution. TCR reactivity to SOX2 expressing cell lines was assessed by FACS analysis and in vitro cytotoxicity assays (4h 51Cr-release, xCELLigence Real Time Cell Analysis). Results Two high-affinity peptides were identified, and their immunogenicity confirmed on peptide-expanded T cell cultures using peptide/MHC (p/MHC) multimers and in IFN-gamma ELISpot assays. In-vitro generated SOX2-specific CD8+ T cells provided a source of TCRs for further characterization and studies. Here, we described a SOX2 TCR with high-antigen affinity for p/MHC complexes as determined in peptide titration assays. This SOX2 TCR was efficiently expressed, as detected by p/MHC multimers, on TCR-null CD8+ T cells derived from healthy donors. Transgenic TCR expression confers T cells with in-vitro recognition and lytic activity against SOX2+ cancer cell lines of various histologies in short- and long-term cytotoxicity assays (figure 1). Conclusions Our findings demonstrate SOX2 is a novel immunological target that may enable the development of TCR engineered adoptive T-cell therapy for cancer patients whose tumor expresses this stem cell transcription factor. Ethics Approval The University of Pennsylvania Institutional Review Board approved this project, and informed consent was obtained from all patients.
Institution: University of Pennsylvania
Language: English
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: hybrid
OpenAlex ID: W4404064966