Immune Gene Expression Profile in Hepatocellular Carcinoma and Surrounding Tissue Predicts Time to Tumor Recurrence

Abstract

Background: The antitumor immune response may play a major role in the clinical outcome of hepatocellular carcinoma (HCC). We characterized the liver immune microenvironment by direct hybridization of RNA extracted from HCC and nontumorous tissues. Methods: RNA was extracted from frozen liver tissue samples of HCC (T; n = 30) and nontumorous tissues (NT; n = 33) obtained from 38 patients. Matched samples were available for 25 patients. The immune gene expression profile was analyzed with the nCounter GX Human Immunology v2 system (NanoString Technologies), which detects the expression levels of 579 immune response-related genes simultaneously. Results: Since the immune gene expression profile of T and NT tissues was significantly different, the prognostic relevance of the liver immune microenvironment was evaluated in the T and NT samples separately. Unsupervised clustering detected two main clusters of immune gene expression both in T and in NT liver samples. In both cases, the expression clusters identified groups of patients with a significantly different median time to HCC recurrence (TTR) but similar overall survival. Based on T tissue, two groups with median TTR of 19 and 127 months, respectively, were detected (p < 0.005). Expression of genes related to T-cell activation was associated with longer TTR. The analysis of NT tissue discriminated subsets of patients with median TTR of 22 and 68 months (p < 0.05). In contrast to T tissue, a predominant inflammatory immune environment was associated with shorter TTR. Conclusions: Immune gene expression profiles predictive of TTR could be identified both in HCC and in adjacent cirrhotic tissues. Longer TTR was associated with overexpression in T tissue and downregulation in NT tissue of the immune response and of inflammation-related genes.

Immune landscape of hepatocellular carcinoma microenvironment: Implications for prognosis and therapeutic applications

“…In our study, based on selective analysis of immune response-related transcripts, we identified a subset of non-tumorous tissues characterized by globally increased immune gene expression, where all cell types, including both activated and exhausted phenotypes, were predicted to be more represented. 116 This immune gene profile was associated with shorter TTR, consistent with our earlier observations 42…”

“…118 Most cell types of lymphoid and myeloid lineages were more represented in tumours with longer TTR, with special enrichment of cytotoxic cells. 116 Only Treg and Th17 subsets were predicted to be more frequent in tumours with worse prognosis, as described previously. 57,118 In a recent report, RNA sequencing data indicated that an immune landscape rich in T cells and cytotoxic cells, but lacking macrophages and Th2 cells, was positively correlated with patient survival.…”

“…Genes differentially expressed between the two groups were involved in pathways governing the regulation of T cell function, that were predicted to be downregulated. 116 Interestingly, the immune-inhibited gene expression profile was the most significant independent predictor of tumour recurrence. In the attempt of defining the prevalence of infiltrating cell subsets, we analysed the relative expression of immune cell-and function-specific genes.…”

“…46 Our study focused on selected immune response-related genes, also proved a global downregulation of immune gene expression in HCC compared to non-tumorous liver tissue. 116 shown to include two distinct microenvironment-based immune clusters, characterized by a prevalent-adaptive T-cell response and by an exhausted immune response, respectively. 115 The gene signature suggestive of active anti-tumour response was associated with longer time to recurrence and overall survival.…”

Pembrolizumab for the Treatment of Hepatocellular Carcinoma

“…In addition, immune cell infiltration is associated with the clinical outcome of hepatic cancer [20]. …”