Clinicopathologic features, tumor immune microenvironment and genomic landscape of Epstein-Barr virus-associated intrahepatic cholangiocarcinoma

Abstract

Background and aims: Little is known about EBV-associated intrahepatic cholangiocarcinoma (EBVaICC) due to its rarity. We aimed to comprehensively investigate the clinicopathology, tumor immune microenvironment (TIME) and genomic landscape of this entity in southern China.

Methods: We evaluated 303 ICCs using in situ hybridization for EBV, we compared clinicopathological parameters between EBVaICC and nonEBVaICC, and we analyzed EBV infection status, tumor-infiltrating lymphocytes (TILs) and genomic features of EBVaICC by immunohistochemistry, double staining, nested PCR, multiplex immunofluorescence staining, fluorescence in situ hybridization and whole exome sequencing.

Results: EBVaICC accounted for 6.6% of ICCs, with EBV latency type I infection and clonal EBV isolates form. Distinctive clinicopathological characteristics of EBVaICC included female predominance, younger patient predominance, solitary tumor, higher HBV infection rate, lower cirrhotic background and increased lymphoepithelioma-like (LEL) subtype proportion. EBVaICC had a significantly larger TIME component than nonEBVaICC. The LEL subtype of EBVaICC, which had a significantly increased density and proportion of CD20+ B cells and CD8+ T cells, was significantly related to longer 2-year OS and RFS than EBVaICC conventional type and nonEBVaICC. Both PD-1 and PD-L1 in TILs and PD-L1 in tumor cells were overexpressed in EBVaICC. Tumor microenvironment immune type (TMIT) I (PDL1-Tumor+/CD8^-High) was significantly more common in EBVaICC than in nonEBVaICC. Mutated genes in at least three cases, including MUC4, DNAH1, GLI2, LIPE, MYH7, RP11-766F14.2 and WDR36, were uncovered. EBVaICC had different mutational pattern compared with reported liver fluke-associated cholangiocarcinoma and HBV-associated ICC.

Conclusions: EBVaICC, as a subset of ICC, has unique etiological characteristics, clinicopathology and molecular genetics with a significantly larger TIME component. Most cases belong to TMIT I. Paradoxically, patients with EBVaICC could be candidates for immune checkpoint therapy.

Keywords: Epstein-Barr virus; clinicopathology; genomic landscape; intrahepatic cholangiocarcinoma; tumor immune microenvironment.