Hepatocellular carcinoma (HCC) is one of the most common malignancies and causes of death worldwide. In this study, we assessed the correlation between clinicopathologic factors with programmed cell death protein 1 (PD-1) and programmed cell death ligand-1 (PD-L1), and cytotoxic T lymphocyte-associated molecule-4 (CTLA-4) expressions. Furthermore, we analyzed the prognostic significance of these proteins in a subgroup of patients. We retrospectively evaluated the PD-1, PD-L1, and CTLA-4 expressions in 294 HCC tissue microarray samples using immunohistochemistry. PD-1 and PD-L1 expressions were significant related to high CD8+ tumor-infiltrating lymphocytes (TILs) (r = 0.664, p < 0.001 and r = 0.149, p = 0.012). Only high Edmondson-Steiner grade was statistically related to high PD-1 expression. High PD-L1 expression was demonstrated as an independent poor prognostic factor for disease-free survival in addition to previous known factors, size >5 cm and serum albumin ≤3.5 g/dL in high CD8+ TILs group. We have demonstrated that the combined high expression of PD-L1 and CD8+ TIL is an important prognostic factor related to the immune checkpoint pathway in HCC and furthermore, there is a possibility that it could be used as a predictor of therapeutic response. Also, this result would be helpful in evaluating the applicable group of PD-1/PD-L1 blocking agent for HCC patients.
Keywords: Hepatocellular carcinoma; cytotoxic T lymphocyte-associated molecule-4; programmed cell death ligand-1; programmed cell death protein 1; tumor-infiltrating lymphocytes.
© 2017 APMIS. Published by John Wiley & Sons Ltd.