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PD-L1 expression in human cancers and its association with clinical outcomes

Authors Wang X, Teng F, Kong L, Yu J

Received 5 February 2016

Accepted for publication 16 May 2016

Published 12 August 2016 Volume 2016:9 Pages 5023—5039


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Prof. Dr. Geoffrey Pietersz

Xin Wang,1,2,* Feifei Teng,2,3,* Li Kong,2 Jinming Yu2

1School of Medicine and Life Sciences, University of Jinan – Shandong Academy of Medical Sciences, 2Department of Radiation Oncology, Shandong Cancer Hospital and Institute, 3School of Medicine, Shandong University, Jinan, People’s Republic of China

*These authors contributed equally to this work

Abstract: PD-L1 is an immunoinhibitory molecule that suppresses the activation of T cells, leading to the progression of tumors. Overexpression of PD-L1 in cancers such as gastric cancer, hepatocellular carcinoma, renal cell carcinoma, esophageal cancer, pancreatic cancer, ovarian cancer, and bladder cancer is associated with poor clinical outcomes. In contrast, PD-L1 expression correlates with better clinical outcomes in breast cancer and merkel cell carcinoma. The prognostic value of PD-L1 expression in lung cancer, colorectal cancer, and melanoma is controversial. Blocking antibodies that target PD-1 and PD-L1 have achieved remarkable response rates in cancer patients who have PD-L1-overexpressing tumors. However, using PD-L1 as an exclusive predictive biomarker for cancer immunotherapy is questionable due to the low accuracy of PD-L1 immunohistochemistry staining. Factors that affect the accuracy of PD-L1 immunohistochemistry staining are as follows. First, antibodies used in different studies have different sensitivity. Second, in different studies, the cut-off value of PD-L1 staining positivity is different. Third, PD-L1 expression in tumors is not uniform, and sampling time and location may affect the results of PD-L1 staining. Therefore, better understanding of tumor microenvironment and use of other biomarkers such as gene marker and combined index are necessary to better identify patients who will benefit from PD-1/PD-L1 checkpoint blockade therapy.

Keywords: PD-L1, prognostic value, checkpoint blockade, immunotherapy, clinical outcome

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