Comprehensive T-cell immunophenotyping and next-generation sequencing of human papillomavirus (HPV)-positive and HPV-negative head and neck squamous cell carcinomas
2017
The success of
programmed cell death 1(PD-1) inhibition in achieving a clinical response in a subset of
headand
neck squamous cell carcinoma(HNSCC) patients emphasizes the need to better understand the immunobiology of HNSCC. Immunophenotyping was performed for 30 HCSCC patients [16 human papillomavirus (HPV)-positive; 14 HPV-negative] on matched tissue from the primary tumour site, locally metastatic
cervical lymph nodes(LNs), uninvolved local cervical LNs, and peripheral blood. CD4+ and CD8+ T-cell lymphocytes obtained from tissue were analysed for expression levels of the inhibitory receptors PD-1, TIM-3 and
CTLA-4. Next-generation sequencing of the T-cell receptor (TCR) β chain was performed on patients (n = 9) to determine receptor repertoire diversity and for clonality analysis. HPV-negative HNSCC patients, particularly those with stage IV disease, had significantly higher proportions of CD8+ T cells expressing
CTLA-4in tumour tissue (P = 0.0013) and in peripheral blood (P = 0.0344) than HPV-positive patients, as well as higher expression levels of TIM-3+PD-1+ CD8+ T cells (P = 0.0072) than controls. For all patients, PD-1 expression on CD8+ T cells – particularly in HPV-negative HNSCC cases – strongly correlated (r = 0.63, P = 0.013) with tumour size at the primary site. The top CD8+ TCR clones from tumour tissue significantly overlapped with circulating peripheral blood TCR clones (r = 0.946), and HPV-positive patients had frequently expanded TCR clones that were more hydrophobic – and potentially more immunogenic – than those from HPV-negative patients. Collectively, our findings demonstrate, for the first time, that high-stage HPV-negative HNSCC patients with primary tumours at different sites in the head and neck have elevated peripheral
CTLA-4+CD8+ T-cell levels, that tumour-familiar CD8+ T cells are detectable in peripheral blood from HNSCC patients, and that TCRs from HPV-positive HNSCC patients potentially recognize distinctly immunogenic cognate antigens. However, our findings are preliminary, and need to be further confirmed in a larger patient cohort; also, how these factors affect patient response to immunotherapy needs to be determined. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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