Identification of neoantigen-specific T cells and their targets: implications for immunotherapy of head and neck squamous cell carcinoma

To develop a practically applicable method for T-cell receptor (TCR)-engineered T cell immunotherapy targeting neoantigens, we have been attempting to identify neoantigen-specific T cell receptors (TCRs) and establish TCR-engineered T cells in a 3-4-month period. In this study, we report the characterization of T cell repertoires in tumor microenvironment (TME) and identification of neoantigen-specific TCRs after stimulation of patient-derived T cells. We screened 15 potential neoantigen peptides and successfully identified two CD8(+)HLA-dextramer(+) T cells, which recognized MAGOHB(G17A) and ZCCHC14(P368L). All three dominant TCR clonotypes from MAGOHB(G17A)-HLA dextramer-sorted CD8(+) T cells were also found in T cells in TME, while none of dominant TCR clonotypes from ZCCHC14(P368L)-HLA dextramer-sorted CD8(+) T cells was found in the corresponding TME. The most dominant TCRA/TCRB pairs for these two neoantigens were cloned into HLA-matched healthy donors' T lymphocytes to generate TCR-engineered T cells. The functional assay showed MAGOHB(G17A) TCR-engineered T cells could be significantly activated in a mutation-specific, HLA-restricted and peptide-dose-dependent manner while ZCCHC14(P368L) TCR-engineered T cells could not. Our data showed neoantigen-reactive T cell clonotypes that were identified in the patient's peripheral blood could be present in the corresponding TME and might be good TCRs targeting neoantigens.