Epithelial–mesenchymal Transition Phenotype and Peritumoral Immune Cell Infiltration in Advanced Biliary Tract Cancer

BackgroundWe evaluated the clinical implications of epithelial–mesenchymal transition (EMT) markers and peritumoral immune cell infiltration in patients with biliary tract cancer (BTC) treated with gemcitabine plus cisplatin (GemCis).MethodsForty-five patients with advanced BTC who received GemCis were included as the study population. We conducted multiplex immunohistochemistry and examined EMT markers and their correlations with immune cell infiltrate at the invasive tumor margin. Study population was subdivided into two groups: twenty-four patients with overall survival (OS) less than 10 months (short-term survivor group, SS) and 21 with OS of 20 months or longer (long-term survivor group, LS).ResultsThe density of tumor cells expressing epithelial marker E-cadherin (E-cadherin+ CK+) at the invasive tumor margin tended to be higher in the LS group than in the SS group (p = 0.065). The density of tumor cells expressing mesenchymal marker vimentin (vimentin+ CK+) was significantly higher in the SS group than in the LS group (p = 0.021). Accordingly, the density of E-cadherin- vimentin+ CK+ cells was also significantly higher in the SS group (p = 0.020). The density of OX40 expressing cells (OX40+) was significantly higher in the SS group than in the LS group (p = 0.006). The density of vimentin+ CK+ cells was positively correlated with FoxP3+ CD4+ regulatory T-cells (r = 0.29, p = 0.047) and OX40+ cells (r = 0.48, p < 0.001).ConclusionsEMT-related features were enriched in BTC patients with poor survival outcomes and were associated with the immunosuppressive tumor microenvironment.