Intra- and Extrahepatic Cholangiocarcinomas Display Differing Sensitivities to NK Cell Lysis and Modulate NK Cell Function through Shared and Distinct Pathways.

Cholangiocarcinoma (CCA) is a rare cancer that arises from the bile duct and is broadly classified by the location of the tumor as either intrahepatic cholangiocarcinoma (iCCA) or extrahepatic cholangiocarcinoma (eCCA). Immunotherapy has revolutionized cancer treatment, yet its utility in CCA has been limited as the tumor microenvironment (TME) in CCA is poorly understood compared with other common cancers. Utilizing previously published transcriptome data, our reanalysis has revealed that CCA has one of the highest relative levels of NK cells, a potent cytotoxic immune cell, compared with other cancers. However, despite iCCA and eCCA having comparable relative levels of NK infiltration, NK cell infiltration only correlated with survival in patients with eCCA. Our subsequent investigation revealed that although iCCA and eCCA profoundly altered NK activity, eCCA had a significantly reduced impact on NK functionality. Whereas iCCA was resistant to long-term NK coculture, eCCA was markedly more sensitive. Moreover, although both iCCA and eCCA dysregulated key NK-activating receptors, eCCA coculture did not impact NKp30 nor NKp44 expression. Furthermore, tumor transcriptome analysis of NKHigh CCA samples revealed a modulation of multiple immune and nonimmune cell types within the TME. Implications: These studies are the first to investigate how iCCA and eCCA impact NK cell functionality through shared and distinct mechanisms and how elevated NK cell infiltration could shape the CCA TME in a subtype-dependent manner.