Many signaling pathways, including Wnt/β-catenin, TGF signaling pathway, (an inhibitor of atypical protein kinase C-i) aPKC-i/phosphorylated transcription factor Sp1 (P-Sp1)/snail family transcriptional repressor (Snail) signaling pathway, hippo pathway, B7H1/PD1 pathway, and FAS/FASL pathway, are implicated in the malignant potential of CCA, as well as in immune evasion by inducing apoptosis of TILs [66–73]. Here, PDCD1 is linked to cholangiocarcinoma.