Immune cell atlas of cholangiocarcinomas reveals distinct tumor microenvironments and associated prognoses

Abstract

Background Immunotherapy has demonstrated a limited clinical efficacy in approximately 5% of cholangiocarcinoma. The main challenges for an effective immunotherapy response in cholangiocarcinoma arise from the tumor microenvironment, which is poorly understood. Methods For a comprehensive analysis of the tumor microenvironment in cholangiocarcinoma, we performed multiplex immunohistochemistry with two 15-marker immune panels and Nanostring assays for a comprehensive analysis of 104 surgically resected cholangiocarcinomas including intrahepatic, hilar, and distal cholangiocarcinoma. We also validated some key findings with a batch integration analysis of published single cell RNA sequencing data. Results This study found that natural killer cells occupy the largest immune cell compartment in cholangiocarcinoma. Granzyme-B+CD8+ effector T cells are significantly associated with better overall survival in both intrahepatic and distal cholangiocarcinoma. Above 85% of intrahepatic cholangiocarcinomas with higher density of PD-1−EOMES−CD8+ effector T cells are associated with long-term survival. However, only the density of PD-1−EOMES−CD8+ T cells in the tumor areas, but not in the peripheries of the tumors, is prognostic. In all three cholangiocarcinoma subtypes, T regulator cells are significantly associated with a poor prognosis; however, M1 and M2 tumor-associated macrophages or PD-L1+ tumor-associated macrophage demonstrate different prognostic values. Combining PD-L1+ M1 or M2, PD-L1− M1 or M2 tumor-associated macrophages, and T regulator cells to subgroup intrahepatic and distal cholangiocarcinoma, the prognosis is significantly better distinguished. Moreover, PD-L1− M2 tumor-associated macrophages is associated with a good prognosis in intrahepatic and distal cholangiocarcinoma, suggesting this subtype of M2 tumor-associated macrophages may be antitumoral. Interestingly, lower densities of various types of immunosuppressive cells are associated with decreased infiltration of effector T cells in distal and hilar cholangiocarcinoma, but not in intrahepatic cholangiocarcinoma. In intrahepatic cholangiocarcinoma, PD-L1+ tumor-associated macrophages exert their immunosuppressive function likely through promoting T cell exhaustion. Conclusions This study suggests that the densities of Granzyme-B+CD8+ effector T cells and non-exhausted PD-1−EOMES−CD8+ T cells and the PD-L1 status in the tumor-associated macrophages are prognostic makers in cholangiocarcinomas. The study also supports targeting PD-L1+ tumor-associated macrophages as the immunotherapy for cholangiocarcinoma.

Targeting macrophages: a novel treatment strategy in solid tumors

“…Tumor microenvironment (TME) consists of peripheral blood vessels, stromal cells, endothelial cells, tumor-associated fibroblasts, and immune cells [ 1 – 3 ]. There are several types of immune cells in the TME, including T cells, natural killer (NK) cells, dendritic cells (DCs), neutrophils, macrophages, and myeloid-derived suppressor cells (MDSCs) [ 4 – 6 ].…”

Mature dendritic cells enriched in immunoregulatory molecules (mregDCs): A novel population in the tumour microenvironment and immunotherapy target

“… 67 DCs, but just not macrophages, exhibited enhanced CD8 + T‐cell antitumour responses when PD‐L1 was deleted, significantly limiting tumour growth. 68 This suggests that PD‐L1 expression in mregDCs, a vital target for immunology, is crucial in the response to ICB treatment. 69 Evaluation of a gene expression dataset of pembrolizumab‐treated breast cancer patients revealed that the relative frequency of mregDCs correlated positively with T‐cell expansion following anti‐PD‐1 treatment, and mregDCs supported T‐cell function in responders, both at baseline and during treatment.…”

The Stroma and Tumor Microenvironment Are Not the Most Instrumental Players in Tumor Cells Immune Evasion, Growth, and Resistance to Therapy

“…Each and every cell of the TME of every cancer type has been identified, accused of initiating and promoting carcinogenesis and metastasis, leading to generation of specific drugs and inhibitors and an array of clinical trials, with resulting limited anti-tumor efficacy and a plethora of adverse reactions. [103][104][105][106][107] Exosomes are endosomes-derived, minute, extracellular vesicles that contain non-coding RNA, proteins and lipids, originating from cancer and TME cells. Exosomes have also been implicated in cancer initiation, progression and therapy resistance via exchanging diverse signaling interactions that vary extensively by organ, cancer type, and patient, and are thus extremely difficult to control.…”