BioScience Trends. 2019;13(1):58-69. (DOI: 10.5582/bst.2019.01003)

Programmed death ligand-1, tumor infiltrating lymphocytes and HLA expression in Chinese extrahepatic cholangiocarcinoma patients: Possible immunotherapy implications.

Yu F, Gong L, Mo Z, Wang WR, Wu ML, Yang JH, Zhang QQ, Li L, Yao JJ, Dong JH


Immunotherapy might be an effective treatment in extrahepatic cholangiocarcinoma (eCCA), a tumor with extremely limited therapeutic options. Our study is to characterize the programmed death ligand-1 (PD-L1) protein expression and cancer microenvironment profiles in surgically resected eCCA samples. PD-L1 positivity was observed on tumor cells (32.3%) as well as on tumor-associated macrophages (74.2%). PD-L1 expression by eCCA correlated significantly with immune parameters such as intra-tumoral CD3+ tumor infiltrating lymphocytes (TILs) density (P = 0.002), intra-tumoral CD8+ TILs density (P < 0.001), and the expression pattern of human leukocyte antigen (HLA) class I (P < 0.001). Immunofluorescence showed that PD-L1 positive tumor cells were adjacent to PD-1 positive cells and the stroma covered with interferon-γ. Correlation with clinicopathological parameters and survival analyses revealed that PD-L1 positivity in eCCA was related to the absence of venous invasion (P = 0.030), improved overall survival (P = 0.020) and progressionfree survival (P = 0.011). HLA class I molecules defect, which is an important mechanism of immune evasion, was frequently observed in eCCA (50.0%) and was associated with a decreased number of intra-tumoral CD8+ TIL density (P = 0.028). Additionally, the presence of unusually high numbers of tumor-associated macrophages (TAMs) subsets M2 in most of eCCA (74.2%) was noted. Our study indicated that PD-L1 expression in association with intra-tumoral TILs infiltration and HLA class I expression in 32.3% of the eCCA reflects an active immune microenvironment potentially responsive to PD-1/PD-L1 inhibitors. In addition, the combination of macrophage-targeting agents may provide therapeutic synergy for future immunotherapy.

KEYWORDS: Extrahepatic cholangiocarcinoma, PD-L1, TILs, HLA class I molecules, TAMs

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