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Programmed death-ligand 1 expression correlates with diminished CD8+ T cell infiltration and predicts poor prognosis in anal squamous cell carcinoma patients

Authors Zhao Y, Sun WP, Peng J, Deng Y, Fang Y, Huang J, Zhang H, Wan D, Lin J, Pan Z

Received 13 October 2017

Accepted for publication 22 November 2017

Published 18 December 2017 Volume 2018:10 Pages 1—11


Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Akshita Wason

Peer reviewer comments 2

Editor who approved publication: Prof. Dr. Alexandra R. Fernandes

Yu-Jie Zhao,1 Wei-Peng Sun,2 Jian-Hong Peng,1 Yu-Xiang Deng,1 Yu-Jing Fang,1 Jun Huang,2 Hui-Zhong Zhang,3 De-Sen Wan,1 Jun-Zhong Lin,1,* Zhi-Zhong Pan,1,*

1Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 2Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, 3Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China

*These authors contributed equally to this work

Objective: Increased expression of programmed death-ligand 1 (PD-L1) on tumor cells can be found in various malignancies; however, very limited information is known about its role in anal squamous cell carcinoma (ASCC). This study explored PD-L1 expression in ASCC patients and its association with patients’ clinicopathological features, CD8+ T cell infiltration, and prognosis.
Methods: Formalin-fixed paraffin-embedded tumor samples from 26 patients with ASCC were retrieved. The levels of PD-L1 expression on the membrane of both tumor cells and tumor-infiltrating mononuclear cells (TIMCs) were evaluated by immunohistochemistry. CD8+ T cell densities, both within tumors and at the tumor–stromal interface, were also analyzed. Baseline clinicopathological characteristics, human papilloma virus (HPV) status, and outcome data correlated with PD-L1-positive staining.
Results: PD-L1 expression on tumor cells and TIMCs was observed in 46% and 50% of patients, respectively. Nineteen patients (73%) were HPV positive, with 7 showing PD-L1-positive staining on tumor cells and 9 showing PD-L1-positive staining on TIMCs. Increasing CD8+ density within tumors, but not immune stroma, was significantly associated with decreased PD-L1 expression by both tumor cells and TIMCs (P=0.0043 and P=0.0007). Patients with negative PD-L1 expression had significantly better progression-free survival (P=0.038 and P=0.0443) and a non-statistically significant trend toward longer overall survival (P=0.0882 and P=0.1222) compared with patients with positive PD-L1 expression.
Conclusion: PD-L1 is widely expressed on the membrane of tumor cells and TIMCs in ASCCs. Its negative impact on prognosis may be due to the diminished CD8+ T cell infiltration within tumors.

Keywords: CD8, PD-L1, HPV, tumor infiltrating mononuclear cells

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