Deniger et al. analyzed resected ovarian cancer metastases in seven women to identify the neoantigen specificity of TILs. Eight mutations generated neoantigen-specific T cells in five women, including a single mutation which generated three epitopes that could each bind a separate HLA. Three CD8+ and nine CD4+ specificities were observed. CD4+ T cells recognizing either of two recurrent TP53 mutations (p53Y220C or p53G245S) were identified in separate patients. The identification of mutation-reactive T cells infiltrating ovarian cancer metastases opens possibilities for TCR-based adoptive cell transfer.

PURPOSE: This was a study prospectively evaluating intratumoral T-cell responses to autologous somatic mutated neoepitopes expressed by human metastatic ovarian cancers. EXPERIMENTAL DESIGN: Tumor infiltrating lymphocytes (TILs) were expanded from resected ovarian cancer metastases, which were analyzed by whole exome and transcriptome sequencing to identify autologous somatic mutations. All mutated neoepitopes, independent of prediction algorithms, were expressed in autologous antigen presenting cells then co-cultured with TIL fragment cultures. Secretion of interferon-gamma or up-regulation of 41BB indicated a T-cell response. RESULTS: Seven women with metastatic ovarian cancer were evaluated and 5 patients had clear, dominant T-cell responses to mutated neoantigens, which were corroborated by comparison to the wild type sequence, identification of the minimal epitope, human leukocyte antigen (HLA) restriction element(s) and neoantigen-specific T-cell receptor(s). Mutated neoantigens were restricted by HLA-B, -C, -DP, -DQ and/or -DR alleles and appeared to principally arise from random, somatic mutations unique to each patient. We established that TP53 "hotspot" mutations (c.659A>G; p.Y220C and c.733G>A; p.G245S) expressed by two different patient's tumors were immunogenic both in the context of HLA-DRB3*02:02. CONCLUSIONS: Mutation-reactive T cells infiltrated ovarian cancer metastases at sufficient frequencies to warrant their investigation as adoptive cell therapy. Additionally, transfer of TP53 "hotspot" mutation-reactive T-cell receptors into peripheral blood T cells could be evaluated as a gene therapy for a diverse range of tumor histologies.

Author Info: (1) Surgery Branch, National Cancer Institute. (2) Surgery Branch, National Cancer Institute. (3) Surgery Branch, National Cancer Institute. (4) CGB, NHGRI/NIH. (5) Surgery Branch,

Author Info: (1) Surgery Branch, National Cancer Institute. (2) Surgery Branch, National Cancer Institute. (3) Surgery Branch, National Cancer Institute. (4) CGB, NHGRI/NIH. (5) Surgery Branch, National Cancer Institute. (6) Surgery Branch, National Cancer Institute. (7) Surgery, National Cancer Institute. (8) Bioinformatics core, National Institutes of Health. (9) Surgery Branch, National Cancer Institute. (10) Surgery Branch, National Cancer Institute. (11) Surgery, National Cancer Institute. (12) Surgery Banch, National Cancer Institute, NIH. (13) Surgery Branch, National Cancer Institute. (14) Surgery Branch, National Cancer Institute sar@mail.nih.gov.