Structural basis for oligoclonal T cell recognition of a shared p53 cancer neoantigen.

Adoptive cell therapy (ACT) with tumor-specific T cells can mediate cancer regression. The main target of tumor-specific T cells are neoantigens arising from mutations in self-proteins. Although the majority of cancer neoantigens are unique to each patient, and therefore not broadly useful for ACT, some are shared. We studied oligoclonal T-cell receptors (TCRs) that recognize a shared neoepitope arising from a driver mutation in the p53 oncogene (p53R175H) presented by HLA-A2. Here we report structures of wild-type and mutant p53–HLA-A2 ligands, as well as structures of three tumor-specific TCRs bound to p53R175H–HLA-A2. These structures reveal how a driver mutation in p53 rendered a self-peptide visible to T cells. The TCRs employ structurally distinct strategies that are highly focused on the mutation to discriminate between mutant and wild-type p53. The TCR–p53R175H–HLA-A2 complexes provide a framework for designing TCRs to improve potency for ACT without sacrificing specificity. Developing broadly applicable neoantigen-directed adoptive cell therapies (ACTs) is challenging because each cancer patient has an unique neoantigen repertoire. Here, the authors present the crystal structures of tumor-specific T cell receptors (TCRs) that recognize a shared neoepitope arising from the R175H driver mutation in the p53 oncogene (p53R175H) alone and bound to p53R175H–HLA-A2, which are of interest for the structure-guided design of TCRs to improve T cell potency for ACT.