The positive prognostic effect of stromal CD8+ tumor-infiltrating T cells is restrained by the expression of HLA-E in non-small cell lung carcinoma
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Mehrdad Talebian Yazdi1, Sander van Riet1, Annemarie van Schadewijk1, Marta Fiocco3,4, Thorbald van Hall2, Christian Taube1, Pieter S. Hiemstra1, Sjoerd H. van der burg2
1Department of Pulmonology, Leiden University Medical Center, Leiden, The Netherlands
2Department of Clinical Oncology, Leiden University Medical Center, Leiden, The Netherlands
3Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands
4Institute of Mathematics, Leiden University, Leiden, The Netherlands
Sjoerd H. van der burg, e-mail: firstname.lastname@example.org
Keywords: CD8+ T cells, HLA class I, HLA-E, non-small cell lung cancer, survival
Received: August 23, 2015 Accepted: November 21, 2015 Published: December 02, 2015
INTRODUCTION: Tumor-infiltrating CD8+ T cells are associated with improved clinical outcomes in non-small cell lung cancer (NSCLC). Here we studied their prognostic effect in the context of the expression of HLA molecules that are key in tumor recognition (HLA-A, B and C) or suppression of immunity (HLA-E) as this is still unknown.
METHODS: Tumor tissue of 197 patients with resected pulmonary adenocarcinoma was analyzed for the presence of CD8+ T cells and the expression of β2-microglobulin, HLA-A, HLA-B/C and HLA-E. The relation of these parameters with overall survival (OS) was assessed.
RESULTS: Loss and low expression of HLA-A or HLA-B/C was found in 44% and 75% of cases respectively. A high CD8+ tumor infiltration was strongly associated with clinical benefit only when the tumors retained good expression of HLA-A and HLA-B/C (p=0.004). In addition, more than 70% of the tumors were found to display a high expression of HLA-E. The expression of HLA-E by tumor cells was an independent negative prognostic factor for OS (p=0.031). Importantly, a dense stromal CD8+ T cell infiltration was strongly associated with improved OS only in HLA-E negative tumors (p=0.005) and its prognostic effect was completely abolished when tumors highly expressed HLA-E (p=0.989).
CONCLUSIONS: CD8+ T cell infiltration strongly contributes to a better prognosis in NSCLC when the tumor cells retain the expression of classical HLA class I and do not express HLA-E. Therefore, analysis of HLA-A, -B/C and HLA-E expression should be included as biomarkers to predict the response to immunotherapy.
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