Abstract
Cholangiocarcinoma (CCA) is a deadly cancer, characterized by abundant stroma. The tumor microenvironment (TME) plays an important role in its aggressive behavior and poor response to therapeutics; however, the underlying pathways are unknown. To fill this gap, we used multiplexed immunohistochemistry, high-dimensional cytometry, and single cell transcriptomics. Our findings confirm an abundance of regulatory T cells (Tregs) and a lack of effector memory T cells within the tumor. Tumor-infiltrating T cells show signs of exhaustion. Using our transcriptomic data, we revealed cellular crosstalk in poor prognosis patients. This crosstalk is driven by stromal cells and macrophages. Among the responsible receptor-ligand pairs are GAS6-AXL, VCAN-TLR2, and EGFR-TGF-β. The multiple mechanisms leading to the exclusion of relevant immune cells needed for an anti-cancer response and mechanisms leading to active immune suppression are part of complex cell-cell crosstalk. This study provides a deeper insight into the immune exhausted phenotype in CCA.