Implication of CD69+CD103+ Tissue‐resident‐like CD8+ T cells as a Potential Immunotherapeutic Target for Cholangiocarcinoma

BACKGROUND The heterogeneous immune landscapes of intrahepatic cholangiocarcinoma (ICC) remain largely unknown. Here we aimed to investigate the implications of tissue-resident memory (TRM)-related features of tumour-infiltrating CD8+ T cells (CD8+ TILs) from ICC patients. METHODS From ICC patients, we obtained blood samples and ICC surgical specimens (n = 33). We performed multicolour flow cytometry, multiplexed immunohistochemistry and RNA sequencing. RESULTS When compared to peripheral CD8+ T cells, the CD8+ TILs included significantly higher proportions of the CD69+ CD103- and CD69+ CD103+ TRM-like subsets (P < .001 for both). Relative to CD69- and CD69+ CD103- cells, the CD69+ CD103+ CD8+ TILs harboured higher levels of T-cell markers representing tumour specificity (ie CD39), proliferation (ie Ki-67) and T-cell activation (ie HLA-DR and CD38) (all P < .001). Moreover, compared to the stroma, the tumour margin and core density each had a significantly higher density of CD103+ CD8+ TILs (P < .001 for both). ICCs with high proportions of CD69+ CD103+ cells displayed higher levels of parameters associated with response to immune checkpoint inhibitors (ICIs)-including number of CD8+ TIL infiltrates (P = .019), PD-L1 expression in the tumour (P = .046) and expression of the T cell-inflamed gene signature (P < .001). ICCs with lower proportions of CD69+ CD103+ CD8+ TILs exhibited significant enrichment of genes related to the Wnt/β-catenin (P < .001) and TGF-β pathways (P = .002). CONCLUSION CD69+ CD103+ TRM-like CD8+ TILs represent prominent tumour-specific immune responses and hold promise as a potential therapeutic target in ICC patients. Differential TRM-related features of ICCs may help develop future immunotherapeutic strategies such as maximizing TRM responses or inhibiting pathways contributing to immune evasion.