Tonsillar Cancer with High CD8+ T-Cell Infiltration Features Increased Levels of Dendritic Cells and Transcriptional Regulation Associated with an Inflamed Tumor Microenvironment.

Abstract

Simple SummaryHuman papilloma virus (HPV) infection is the leading cause of tonsillar cancer (TC), and HPV+ TC has a favorable prognosis as compared to HPV− TC. Further, high levels of CD8+ T-cells in TC are associated with a favorable prognosis. Increased understanding of the tumor immune microenvironment is needed to identify prognostic biomarkers and novel treatment targets. In this study, we assess the immune profiles of fresh TC biopsies and contralateral healthy tissue against a detailed HPV analysis, including DNA quantification and RNA expression analysis. We demonstrate a correlation between levels of CD8+ T-cells and antigen-presenting cells in TC, and we further present differentially expressed biomarkers and signaling pathways in CD8HIGH vs. CD8LOW HPV+ TC. Our study thus describes immune phenotypes and the heterogeneity of the immune compartment in HPV+ TC. Further studies are warranted to assess if this information can be used on an individual basis to aid in prognosis and treatment decisions.Human papillomavirus (HPV) is the main causal agent of tonsillar cancer (TC) and HPV+ TC has a favorable prognosis compared to HPV− disease. In this study, we examined aspects of the tumor microenvironment of TC, focusing on T-cells, dendritic cells (DC), and macrophages. Fresh biopsies of TC and the contralateral healthy tonsil (HT) were obtained from 20 patients, analyzed by multiparameter flow cytometry, and assessed against a detailed HPV-status. Additionally, RNA-sequencing data from 38 TC samples available in the public database, The Cancer Genome Atlas (TCGA), were explored, focusing on the same leukocyte populations. HPV+ TC featured increased levels of CD8+ T-cells and antigen-presenting cells (cf. HPV− TC and HT, respectively). In HPV+ TC, CD8+ T-cell frequencies correlated to DC levels independently of tumor stage, HPV 16 copy number, and E7 oncogene expression as well as frequencies of other leukocytes. Similarly, RNA sequencing data were explored by dividing the HPV+ TCs according to predefined CD8+ T-cell scores in silico. Higher levels of genes expressed by antigen-presenting cells and effector T-cells, such as immune checkpoints and cytokines, were detected in the CD8HIGH HPV+ TC samples (cf. CD8LOW HPV+ TC). In conclusion, CD8HIGH HPV+ TC displays a unique inflammatory profile associated with increased effector T-cell functions and the presence of antigen-presenting cells in the tumor microenvironment. Further studies are warranted to assess if this information can be used on an individual basis to aid in prognosis and treatment decisions.