Molecular Signature and Immune Landscape of HCV-Associated Hepatocellular Carcinoma (HCC): Differences and Similarities with HBV-HCC

Hepatitis C virus and hepatocellular carcinoma: carcinogenesis in the era of direct-acting antivirals

Chronic hepatitis C virus (HCV) infection is a major cause of hepatic fibrosis and cirrhosis, with a risk for the development of hepatocellular carcinoma (HCC). Although highly effective direct-acting antivirals (DAAs) are available, the incidence, morbidity, and mortality of HCV-associated HCC are still high. This article reviews the current knowledge of the mechanisms of HCV-induced carcinogenesis with a special focus on those processes that continue after virus clearance and outlines implications for patient surveillance after DAA treatment.

HCV- and HBV-mediated liver cancer converge on similar transcriptomic landscapes and immune profiles

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related deaths worldwide, and a large proportion of HCC is attributable to viral causes including hepatitis B (HBV) and C virus (HCV). The pathogenesis of viral-mediated HCC can differ between HBV and HCV, but it is unclear how much these differences influence the tumors' final molecular and immune profiles. Additionally, there are known sex differences in the molecular etiology of HCC, but sex differences have not been explored in the context of viral-mediated HCC. To determine the extent to which the viral status and sex impact the molecular and immune profiles of HCC, we performed differential expression and immune cell deconvolution analyses. We identified a large number of differentially expressed genes unique to the HBV or HCV tumor:tumor-adjacent comparison. Pathway enrichment analyses demonstrated that the changes unique to the HCV tumor:tumor-adjacent tissue were predominated by changes in the immune pathways. Immune cell deconvolution demonstrated that HCV tumor-adjacent tissue had the largest immune cell infiltrate, with no difference in the immune profiles within HBV and HCV tumor samples. We subsequently segregated the differential expression analyses by sex, but demonstrated that the low number of female samples led to an overestimate of differentially expressed genes unique to male tumors. This limitation highlights the importance of additional sampling of female HCC tumors to allow for a more complete analysis of the sex differences in HCC. Overall, this work demonstrates the convergence of HBV- and HCV-mediated HCC on a similar transcriptomic landscape and immune profile despite differences in the surrounding tissue.

After the Storm: Persistent Molecular Alterations Following HCV Cure

The development of direct-acting antivirals (DAAs) against hepatitis C virus (HCV) has revolutionized the management of this pathology, as their use allows viral elimination in a large majority of patients. Nonetheless, HCV remains a major public health problem due to the multiple challenges associated with its diagnosis, treatment availability and development of a prophylactic vaccine. Moreover, HCV-cured patients still present an increased risk of developing hepatic complications such as hepatocellular carcinoma. In the present review, we aim to summarize the impact that HCV infection has on a wide variety of peripheral and intrahepatic cell populations, the alterations that remain following DAA treatment and the potential molecular mechanisms implicated in their long-term persistence. Finally, we consider how recent developments in single-cell multiomics could refine our understanding of this disease in each specific intrahepatic cell population and drive the field to explore new directions for the development of chemo-preventive strategies.

Identification of Two Distinct Immune Subtypes in Hepatitis B Virus (HBV)-Associated Hepatocellular Carcinoma (HCC)

HBV is the most common risk factor for HCC development, accounting for almost 50% of cases worldwide. Despite significant advances in immunotherapy, there is limited information on the HBV-HCC tumor microenvironment (TME), which may influence the response to checkpoint inhibitors. Here, we characterize the TME in a unique series of liver specimens from HBV-HCC patients to identify who might benefit from immunotherapy. By combining an extensive immunohistochemistry analysis with the transcriptomic profile of paired liver samples (tumor vs. nontumorous tissue) from 12 well-characterized Caucasian patients with HBV-HCC, we identified two distinct tumor subtypes that we defined immune-high and immune-low. The immune-high subtype, seen in half of the patients, is characterized by a high number of infiltrating B and T cells in association with stromal activation and a transcriptomic profile featuring inhibition of antigen presentation and CTL activation. All the immune-high tumors expressed high levels of CTLA-4 and low levels of PD-1, while PD-L1 was present only in four of six cases. In contrast, the immune-low subtype shows significantly lower lymphocyte infiltration and stromal activation. By whole exome sequencing, we documented that four out of six individuals with the immune-low subtype had missense mutations in the CTNNB1 gene, while only one patient had mutations in this gene in the immune-high subtype. Outside the tumor, there were no differences between the two subtypes. This study identifies two distinctive immune subtypes in HBV-associated HCC, regardless of the microenvironment observed in the surrounding nontumorous tissue, providing new insights into pathogenesis. These findings may be instrumental in the identification of patients who might benefit from immunotherapy.

Overview of hepatocellular carcinoma: from molecular aspects to future therapeutic options

Hepatocellular carcinoma (HCC) is the seventh most highly prevalent malignant tumor globally and the second most common cause of mortality. HCC develops with complex pathways that occur through multistage biological processes. Non-alcoholic fatty liver disease, metabolic-associated fatty liver disease, alcoholic liver disease, autoimmune hepatitis, hepatitis B, and hepatitis C are the causative etiologies of HCC. HCC develops as a result of epigenetic changes, protein-coding gene mutations, and altered signaling pathways. Biomarkers and potential therapeutic targets for HCC open up new possibilities for treating the disease. Immune checkpoint inhibitors are included in the treatment options in combination with molecular targeted therapy.

The effect of liver disease on hepatic microenvironment and implications for immune therapy

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the fourth leading cause of cancer-related death worldwide. HCC often occurs in the setting of chronic liver disease or cirrhosis. Recent evidence has highlighted the importance of the immune microenvironment in the development and progression of HCC, as well as its role in the potential response to therapy. Liver disease such as viral hepatitis, alcohol induced liver disease, and non-alcoholic fatty liver disease is a major risk factor for the development of HCC and has been demonstrated to alter the immune microenvironment. Alterations in the immune microenvironment may markedly influence the response to different therapeutic strategies. As such, research has focused on understanding the complex relationship among tumor cells, immune cells, and the surrounding liver parenchyma to treat HCC more effectively. We herein review the immune microenvironment, as well as the relative effect of liver disease on the immune microenvironment. In addition, we review how changes in the immune microenvironment can lead to therapeutic resistance, as well as highlight future strategies aimed at developing the next-generation of therapies for HCC.

Immune Checkpoint Inhibitors in HBV-Caused Hepatocellular Carcinoma Therapy

Hepatitis B virus (HBV) infection is the main risk factor for the development of hepatocellular carcinoma (HCC), the most common type of liver cancer, with high incidence and mortality worldwide. Surgery, liver transplantation, and ablation therapies have been used to treat early HBV-caused HCC (HBV-HCC); meanwhile, in the advanced stage, chemoradiotherapy and drug-targeted therapy are regularly considered, but with limited efficacy. Recently, immunotherapies, such as tumor vaccine therapy, adoptive cell transfer therapy, and immune checkpoint inhibitor therapy, have demonstrated promising efficacy in cancer treatment. In particular, immune checkpoint inhibitors can successfully prevent tumors from achieving immune escape and promote an anti-tumor response, thereby boosting the therapeutic effect in HBV-HCC. However, the advantages of immune checkpoint inhibitors in the treatment of HBV-HCC remain to be exploited. Here, we describe the basic characteristics and development of HBV-HCC and introduce current treatment strategies for HBV-HCC. Of note, we review the principles of immune checkpoint molecules, such as programmed cell death protein 1(PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) in HBV-HCC, as well as related inhibitors being considered in the clinic. We also discuss the benefits of immune checkpoint inhibitors in the treatment of HBV-HCC and the efficacy of those inhibitors in HCC with various etiologies, aiming to provide insights into the use of immune checkpoint inhibitors for the treatment of HBV-HCC.

Advanced development of biomarkers for immunotherapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common liver cancer and one of the leading causes of cancer-related deaths in the world. Mono-immunotherapy and combination therapy with immune checkpoint inhibitors (ICIs) and multitargeted tyrosine kinase inhibitors (TKIs) or anti-vascular endothelial growth factor (anti-VEGF) inhibitors have become new standard therapies in advanced HCC (aHCC). However, the clinical benefit of these treatments is still limited. Thus, proper biomarkers which can predict treatment response to immunotherapy to maximize clinical benefit while sparing unnecessary toxicity are urgently needed. Contrary to other malignancies, up until now, no acknowledged biomarkers are available to predict resistance or response to immunotherapy for HCC patients. Furthermore, biomarkers, which are established in other cancer types, such as programmed death ligand 1 (PD-L1) expression and tumor mutational burden (TMB), have no stable predictive effect in HCC. Thus, plenty of research focusing on biomarkers for HCC is under exploration. In this review, we summarize the predictive and prognostic biomarkers as well as the potential predictive mechanism in order to guide future research direction for biomarker exploration and clinical treatment options in HCC.

The benefit of immunotherapy in patients with hepatocellular carcinoma: a systematic review and meta-analysis

Background: A systemic review of the survival benefit of immune checkpoint inhibitors (ICIs) in phase III hepatocellular carcinoma (HCC) trials was conducted. Methods: Meta-analyses were performed with the generic inverse-variance method with a fixed-effects model. Results: In 10 trials encompassing 6123 patients, ICI-based therapy (monotherapy/combination) improved overall survival (OS) compared with the control arm (hazard ratio [HR]: 0.77; 95% CI: 0.70-0.84; p < 0.001). The survival benefit was consistent across variable treatment lines, Eastern Cooperative Oncology Group performance status and AFP levels. While the OS benefit was more pronounced in hepatitis B-related HCC (HR: 0.70; 95% CI: 0.63-0.77; p < 0.001), OS was improved in hepatitis C-related (HR: 0.83; 95% CI: 0.71-0.98) and nonviral HCC (HR: 0.86; 95% CI: 0.77-0.97). Conclusion: ICI-based therapies should be the standard for all patients with advanced HCC.

Novel Insights into MEG3/miR664a-3p/ADH4 Axis and Its Possible Role in Hepatocellular Carcinoma from an in Silico Perspective

Hepatocellular carcinoma (HCC) is a complex disease involving altered interactomes of transcripts and proteins. MicroRNAs (miRNAs) are small-noncoding RNAs that can interact with specific gene transcripts and an array of other vital endogenous non-coding RNAs (lncRNAs) that can influence gene expression. Maternally Expressed Gene 3 (MEG3) is an imprinted lncRNA that is reported to be downregulated in HCC (in both cell lines and tumors). Alcohol Dehydrogenase 4 (ADH4) is a well-known prognostic protein biomarker for predicting the survival outcomes of patients with hepatocellular carcinoma whose expression is regulated by miR-664a-3p, which is upregulated in HCC. In this study, we performed a battery of robust and systematic in silico analyses to predicate the possible lncRNA-miRNA interactions between MEG3, miR-664a-3p, and ADH4. miRNA-mRNA and lncRNA-miRNA hybrid structures were primarily obtained, and the minimum free energies (MFEs) for the 3'UTR (Untranslated Regions) of ADH4-miR-664a-3p and the 3'UTR of MEG3-miR-664a-3p interactions were assessed to predict the stability of the obtained RNA heteroduplex hybrids. The hybrid with the least minimum free energy (MFE) was considered to be the most favorable. The MFEs were around -28.1 kcal/mol and -31.3 kCal/mol for the ADH4-miR-664a-3p and MEG3-miR-66a-3p RNA hybrids, respectively. This demonstrated that lncRNA-MEG3 might be a competitive endogenous RNA that acts as a molecular sponge for miR-664a-3p. In summary, our interaction analyses results predict the significance of the MEG3/miR-664a-3p/ADH4 axis, where MEG3 downregulation results in miR-664a-3p overexpression and the subsequential underexpression of ADH4 in HCC, as a novel axis of interest that demands further validation.

Immune Microenvironment and Immunotherapeutic Management in Virus-Associated Digestive System Tumors

The development of cancer is a multifactorial phenomenon, while it constitutes a major global health problem. Viruses are an important factor that is involved in tumorigenesis and is associated with 12.1% of all cancer cases. Major examples of oncogenic viruses which are closely associated with the digestive system are HBV, HCV, EBV, HPV, JCV, and CMV. EBV, HPV, JCV, and CMV directly cause oncogenesis by expressing oncogenic proteins that are encoded in their genome. In contrast, HBV and HCV are correlated indirectly with carcinogenesis by causing chronic inflammation in the infected organs. In addition, the tumor microenvironment contains various immune cells, endothelial cells, and fibroblasts, as well as several growth factors, cytokines, and other tumor-secreted molecules that play a key role in tumor growth, progression, and migration, while they are closely interrelated with the virus. The presence of T-regulatory and B-regulatory cells in the tumor microenvironment plays an important role in the anti-tumor immune reaction. The tumor immune microenvironments differ in each type of cancer and depend on viral infection. The alterations in the immune microenvironment caused by viruses are also reflected in the effectiveness of immunotherapy. The present review aims at shedding light on the association between viruses and digestive system malignancies, the characteristics of the tumor immune microenvironment that develop, and the possible treatments that can be administered.

Comparison of Postoperative Prognosis Among HBV-Related, HCV-Related, and Non-HBV Non-HCV Hepatocellular Carcinomas: A Systematic Review and Meta-analysis

Context: Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, and different hepatitis viruses might affect the prognosis of patients with HCC. Objectives: This study aimed to reveal the differences in the postoperative prognosis of patients with hepatitis B virus-related HCC (HBV-HCC), hepatitis C virus-related HCC (HCV-HCC), and non-HBV non-HCV hepatocellular carcinoma (NBNC-HCC). Methods: The databases PubMed, Embase, Cochrane, Web of Science, and Scopus were searched for articles published until April 2022. Stata software version 12 and Review Manager version 5.4 were used to conduct the meta-analysis, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was adopted in this study. Results: In the present study, 26 papers on a total of 20381 participants who met the inclusion criteria were analyzed. The 5-year overall survival in the HBV-HCC and HCV-HCC groups was lower than in the NBNC-HCC group (HBV-HCC vs. NBNC-HCC, P = 0.005; HCV-HCC vs. NBNC-HCC, P = 0.001). Patients with HBV-HCC and HCV-HCC had worse 5-year recurrence-free survival than patients with NBNC-HCC (HBV-HCC vs. NBNC-HCC, P = 0; HCV-HCC vs. NBNC-HCC, P = 0). In addition, the 5-year recurrence-free rate in the HCV-HCC group was lower than in the HBV-HCC group (P = 0). The observed association between serum alpha-fetoprotein levels and the postoperative prognosis was inconsistent in different subgroups. Conclusions: Patients with NBNC-HCC had a significantly better postoperative prognosis than those with virus-related HCC. The alpha-fetoprotein levels significantly correlated with the postoperative prognosis of patients with HCC.

Regulatory T cells and their associated factors in hepatocellular carcinoma development and therapy

Liver cancer is the third leading cause of cancer-related death worldwide with primary type hepatocellular carcinoma (HCC). Factors, including carcinogens, infection of hepatitis viruses, alcohol abuse, and non-alcoholic fatty liver disease (NAFLD), can induce HCC initiation and promote HCC progression. The prevalence of NAFLD accompanying the increased incidence of obesity and type 2 diabetes becomes the most increasing factor causing HCC worldwide. However, the benefit of current therapeutic options is still limited. Intrahepatic immunity plays critically important roles in HCC initiation, development, and progression. Regulatory T cells (Tregs) and their associated factors such as metabolites and secreting cytokines mediate the immune tolerance of the tumor microenvironment in HCC. Therefore, targeting Tregs and blocking their mediated factors may prevent HCC progression. This review summarizes the functions of Tregs in HCC-inducing factors including alcoholic and NAFLD, liver fibrosis, cirrhosis, and viral infections. Overall, a better understanding of the role of Tregs in the development and progression of HCC provides treatment strategies for liver cancer treatment.