Abstract A052: Comprehensive EBV-specific T cell profiling and multi-omics analysis of nasopharyngeal carcinoma CD8 T cells reveals novel cancer-associated phenotype

Abstract

Abstract Nasopharyngeal carcinoma (NPC) is a high mortality, Epstein-Barr virus (EBV)-driven cancer with limited treatment options. Although EBV is highly antigenic and detectable in nearly all NPC tumor cells, it remains unclear why NPC tumors evade immune targeting despite high levels of immune infiltration. Here, we investigate the phenotypes of peripheral EBV-specific T cells with the purpose of identifying clinically relevant, cancer-associated EBV-specific T cell phenotypes. We developed a 34-marker mass cytometry and multiplexed MHC-I tetramer panel to detect and phenotype CD8 T cells of up to 55 antigen-specificities, including EBV and other known viral and cancer-antigen epitopes. We used this approach to profile peripheral blood mononuclear cells (PBMCs) from treatment-naïve NPC patients (n=51). Compared to other antigen-specific T cells detected in NPC patients and EBV-specific T cells in healthy individuals, EBV-specific T cells in NPC patients expressed high levels of activation markers (CD38, HLA-DR), co-inhibitory markers (CD39, TIGIT, PD-1), and migratory markers (ITB7, CD103). Using unsupervised clustering, we found that the frequency of EBV-specific T cells in a phenotypic cluster characterized by high CD103, CD39, HLA-DR, and CD38 expression positively correlated with plasma EBV-DNA titer and gross tumor volume. Remarkably, we observed that regardless of antigen specificity, NPC patients had a higher frequency of total CD8 T cells with this activated/exhausted cluster phenotype. CD8 frequencies of this cluster were also positively correlated with plasma EBV-DNA titer and stage (TNM). To investigate the gene expression profiles and TCR clonal diversity of this cancer-associated phenotype, we performed single-cell multi-omics analysis on peripheral CD8 T cells from NPC patients (n=17). We identified that cell subsets within this phenotype had distinct gene expression patterns indicative of potential associations with the tumor and we also assessed the clonality of these subpopulations. Overall, this study identified a unique cancer-associated peripheral EBV-specific T cell phenotype in the context of nasopharyngeal carcinoma that is positively correlated with advanced disease. Frequencies of peripheral T cells with this phenotype could also be useful as a blood-based prognostic marker for NPC. Citation Format: Nandita Kumar, Long Nguyen, Saumya Jani, Darren WT Lim, Joe PS Yeong, Melvin LK Chua, Amit Jain, Evan W Newell. Comprehensive EBV-specific T cell profiling and multi-omics analysis of nasopharyngeal carcinoma CD8 T cells reveals novel cancer-associated phenotype [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A052.