An open-label, single-arm, phase I/II study of lower-dose decitabine based therapy in patients with advanced hepatocellular carcinoma

Tumor editing suppresses innate and adaptive antitumor immunity and is reversed by inhibiting DNA methylation

Cancer cells edit gene expression to evade immunosurveillance. However, genome-wide studies of gene editing during early tumorigenesis are lacking. Here we used single-cell RNA sequencing in a breast cancer genetically engineered mouse model (GEMM) to identify edited genes without bias. Late tumors repressed antitumor immunity genes, reducing infiltrating immune cells and tumor-immune cell communications. Innate immune genes, especially interferon-stimulated genes, dominated the list of downregulated tumor genes, while genes that regulate cell-intrinsic malignancy were mostly unedited. Naive and activated CD8+ T cells in early tumors were replaced with exhausted or precursor-exhausted cells in late tumors. Repression of immune genes was reversed by inhibiting DNA methylation using low-dose decitabine, which suppressed tumor growth and restored immune control, increasing the number, functionality and memory of tumor-infiltrating lymphocytes and reducing the number of myeloid suppressor cells. Decitabine induced important interferon, pyroptosis and necroptosis genes, inflammatory cell death and immune control in GEMM and implanted breast and melanoma tumors.

Crosstalk between Epigenetics and Metabolic Reprogramming in Metabolic Dysfunction-Associated Steatotic Liver Disease-Induced Hepatocellular Carcinoma: A New Sight

Epigenetic and metabolic reprogramming alterations are two important features of tumors, and their reversible, spatial, and temporal regulation is a distinctive hallmark of carcinogenesis. Epigenetics, which focuses on gene regulatory mechanisms beyond the DNA sequence, is a new entry point for tumor therapy. Moreover, metabolic reprogramming drives hepatocellular carcinoma (HCC) initiation and progression, highlighting the significance of metabolism in this disease. Exploring the inter-regulatory relationship between tumor metabolic reprogramming and epigenetic modification has become one of the hot directions in current tumor metabolism research. As viral etiologies have given way to metabolic dysfunction-associated steatotic liver disease (MASLD)-induced HCC, it is urgent that complex molecular pathways linking them and hepatocarcinogenesis be explored. However, how aberrant crosstalk between epigenetic modifications and metabolic reprogramming affects MASLD-induced HCC lacks comprehensive understanding. A better understanding of their linkages is necessary and urgent to improve HCC treatment strategies. For this reason, this review examines the interwoven landscape of molecular carcinogenesis in the context of MASLD-induced HCC, focusing on mechanisms regulating aberrant epigenetic alterations and metabolic reprogramming in the development of MASLD-induced HCC and interactions between them while also updating the current advances in metabolism and epigenetic modification-based therapeutic drugs in HCC.

Liver-specific deletion of de novo DNA methyltransferases protects against glucose intolerance in high-fat diet-fed male mice

Alterations to gene transcription and DNA methylation are a feature of many liver diseases including fatty liver disease and liver cancer. However, it is unclear whether the DNA methylation changes are a cause or a consequence of the transcriptional changes. It is even possible that the methylation changes are not required for the transcriptional changes. If DNA methylation is just a minor player in, or a consequence of liver transcriptional change, then future studies in this area should focus on other systems such as histone tail modifications. To interrogate the importance of de novo DNA methylation, we generated mice that are homozygous mutants for both Dnmt3a and Dnmt3b in post-natal liver. These mice are viable and fertile with normal sized livers. Males, but not females, showed increased adipose depots, yet paradoxically, improved glucose tolerance on both control diet and high-fat diets (HFD). Comparison of the transcriptome and methylome with RNA sequencing and whole-genome bisulfite sequencing in adult hepatocytes revealed that widespread loss of methylation in CpG-rich regions in the mutant did not induce loss of homeostatic transcriptional regulation. Similarly, extensive transcriptional changes induced by HFD did not require de novo DNA methylation. The improved metabolic phenotype of the Dnmt3a/3b mutant mice may be mediated through the dysregulation of a subset of glucose and fat metabolism genes which increase both glucose uptake and lipid export by the liver. However, further work is needed to confirm this.

Epigenetic therapy: Research progress of decitabine in the treatment of solid tumors

Decitabine's early successful therapeutic outcomes in hematologic malignancies have led to regulatory approvals from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for addressing myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). These approvals have sparked keen interest in exploring the potential of decitabine for treating solid tumors. Continuous preclinical and clinical trials have proved that low doses of decitabine also bring benefits in treating solid tumors, and various proposed mechanisms attempt to explain the potential efficacy. It is important to note that the application of decitabine in solid tumors is still considered investigational. This article reviews the application mechanism and current status of decitabine in the treatment of solid tumors.

Potential Immunotherapy Targets for Liver-Directed Therapies, and the Current Scope of Immunotherapeutics for Liver-Related Malignancies

Liver cancer, including hepatocellular carcinoma and intrahepatic cholangiocarcinoma, is increasing in incidence and mortality across the globe. An improved understanding of the complex tumor microenvironment has opened many therapeutic doors and led to the development of novel pharmaceuticals targeting cellular signaling pathways or immune checkpoints. These interventions have significantly improved tumor control rates and patient outcomes, both in clinical trials and in real-world practice. Interventional radiologists play an important role in the multidisciplinary team given their expertise in minimally invasive locoregional therapy, as the bulk of these tumors are usually in the liver. The aim of this review is to highlight the immunological therapeutic targets for primary liver cancers, the available immune-based approaches, and the contributions that interventional radiology can provide in the care of these patients.

Hydroxymethylation and Epigenetic Drugs: New Insights into the Diagnosis and Treatment in Epigenetics of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a highly lethal and heterogeneous malignancy with multiple genetic alternations and complex signaling pathways. The complexity and multifactorial nature of HCC pose a tremendous challenge regarding its diagnosis and treatment. Emerging evidence has indicated an important regulatory role of epigenetic modifications in HCC initiation and progression. Epigenetic modifications are stably heritable gene expression traits caused by changing the accessibility of chromatin structure and genetic activity without alteration in the DNA sequence and have been gradually recognized as a hallmark of cancer. In addition, accumulating data suggest a potential value of altered hydroxymethylation in epigenetic modifications and therapeutics targeting the epigenetically mediated regulation. As such, probing the epigenetic field in the era of precision oncology is a valid avenue for promoting the accuracy of early diagnosis and improving the oncological prognosis of HCC patients. This review focuses on the diagnostic performance and clinical utility of 5-hydroxymethylated cytosine, the primary intermediate product of the demethylation process, for early HCC diagnosis and discusses the promising applications of epigenetic-based therapeutic regimens for HCC.

Epigenetic modification-related mechanisms of hepatocellular carcinoma resistance to immune checkpoint inhibition

Hepatocellular carcinoma (HCC) constitutes most primary liver cancers and is one of the most lethal and life-threatening malignancies globally. Unfortunately, a substantial proportion of HCC patients are identified at an advanced stage that is unavailable for curative surgery. Thus, palliative therapies represented by multi-tyrosine kinase inhibitors (TKIs) sorafenib remained the front-line treatment over the past decades. Recently, the application of immune checkpoint inhibitors (ICIs), especially targeting the PD-1/PD-L1/CTLA-4 axis, has achieved an inspiring clinical breakthrough for treating unresectable solid tumors. However, many HCC patients with poor responses lead to limited benefits in clinical applications, which has quickly drawn researchers' attention to the regulatory mechanisms of immune checkpoints in HCC immune evasion. Evasion of immune surveillance by cancer is attributed to intricate reprogramming modulation in the tumor microenvironment. Currently, more and more studies have found that epigenetic modifications, such as chromatin structure remodeling, DNA methylation, histone post-translational modifications, and non-coding RNA levels, may contribute significantly to remodeling the tumor microenvironment to avoid immune clearance, affecting the efficacy of immunotherapy for HCC. This review summarizes the rapidly emerging progress of epigenetic-related changes during HCC resistance to ICIs and discusses the mechanisms of underlying epigenetic therapies available for surmounting immune resistance. Finally, we summarize the clinical advances in combining epigenetic therapies with immunotherapy, aiming to promote the formation of immune combination therapy strategies.

DNMT and EZH2 inhibitors synergize to activate therapeutic targets in hepatocellular carcinoma

The development of more effective targeted therapies for hepatocellular carcinoma (HCC) patients due to its aggressiveness is urgently needed. DNA methyltransferase inhibitors (DNMTis) represented the first clinical breakthrough to target aberrant cancer epigenomes. However, their clinical efficacies are still limited, in part due to an "epigenetic switch" in which a large group of genes that are demethylated by DNMTi treatment remain silenced by polycomb repressive complex 2 (PRC2) occupancy. EZH2 is the member of PRC2 that catalyzes the placement of H3K27me3 marks. EZH2 overexpression is correlated with poor HCC patient survival. We tested the combination of a DNMTi (5-aza-2'-deoxycytidine, DAC) and the EZH2 inhibitor (EZH2i) GSK126 in human HCC cell lines on drug sensitivity, DNA methylation, nucleosome accessibility, and gene expression profiles. Compared with single agent treatments, all HCC cell lines studied showed increased sensitivity after receiving both drugs concomitant with prolonged anti-proliferative changes and sustained reactivation of nascently-silenced genes. The increased number of up-regulated genes after combination treatment correlated with prolonged anti-proliferation effects and increased nucleosome accessibility. Combination treatments also activate demethylated promoters that are repressed by PRC2 occupancy. Furthermore, 13-31% of genes down-regulated by DNA methylation in primary HCC tumors were reactivated through this combination treatment scheme in vitro. Finally, the combination treatment also exacerbates anti-tumor immune responses, while most of these genes were downregulated in over 50% of primary HCC tumors. We have linked the anti-tumor effects of DAC and GSK126 combination treatments to detailed epigenetic alterations in HCC cells, identified potential therapeutic targets and provided a rationale for treatment efficacy for HCC patients.

An Insight into the Novel Immunotherapy and Targeted Therapeutic Strategies for Hepatocellular Carcinoma and Cholangiocarcinoma

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) constitute highly malignant forms of primary liver cancers. Hepatocellular and bile duct carcinogenesis is a multiplex process, caused by various genetic and epigenetic alterations, the influence of environmental factors, as well as the implication of the gut microbiome, which was undervalued in the previous years. The molecular and immunological analysis of the above malignancies, as well as the identification of the crucial role of intestinal microbiota for hepatic and biliary pathogenesis, opened the horizon for novel therapeutic strategies, such as immunotherapy, and enhanced the overall survival of cancer patients. Some of the immunotherapy strategies that are either clinically applied or under pre-clinical studies include monoclonal antibodies, immune checkpoint blockade, cancer vaccines, as well as the utilization of oncolytic viral vectors and Chimeric antigen, receptor-engineered T (CAR-T) cell therapy. In this current review, we will shed light on the recent therapeutic modalities for the above primary liver cancers, as well as on the methods for the enhancement and optimization of anti-tumor immunity.

Metabolism-Associated Epigenetic and Immunoepigenetic Reprogramming in Liver Cancer

Metabolic reprogramming and epigenetic changes have been characterized as hallmarks of liver cancer. Independently of etiology, oncogenic pathways as well as the availability of different energetic substrates critically influence cellular metabolism, and the resulting perturbations often cause aberrant epigenetic alterations, not only in cancer cells but also in the hepatic tumor microenvironment. Metabolic intermediates serve as crucial substrates for various epigenetic modulations, from post-translational modification of histones to DNA methylation. In turn, epigenetic changes can alter the expression of metabolic genes supporting on the one hand, the increased energetic demand of cancer cells and, on the other hand, influence the activity of tumor-associated immune cell populations. In this review, we will illustrate the most recent findings about metabolic reprogramming in liver cancer. We will focus on the metabolic changes characterizing the tumor microenvironment and on how these alterations impact on epigenetic mechanisms involved in the malignant progression. Furthermore, we will report our current knowledge about the influence of cancer-specific metabolites on epigenetic reprogramming of immune cells and we will highlight how this favors a tumor-permissive immune environment. Finally, we will review the current strategies to target metabolic and epigenetic pathways and their therapeutic potential in liver cancer, alone or in combinatorial approaches.

HCC and Molecular Targeting Therapies: Back to the Future

Hepatocellular carcinoma (HCC) is one of the leading causes of death from cancer in the world. Recently, the effectiveness of new antiviral therapies and the HBV vaccine have reduced HCC’s incidence, while non-alcoholic steato-hepatitis is an emerging risk factor. This review focuses on antiangiogenic molecules and immune checkpoint inhibitors approved for HCC treatment and possible future approaches. Sorafenib was the first drug approved for the treatment of advanced HCC (aHCC) and it has been shown to increase survival by a few months. Lenvatinib, a multikinase inhibitor, has shown non-inferiority in survival compared with sorafenib and an improvement in progression-free survival (PFS). The combination of atezolizumab (an anti-PDL1 antibody) and bevacizumab (an anti-VEGF antibody) was the first drug combination approved for HCC, demonstrating improved survival compared with sorafenib (19.2 vs. 13.4 months). As a second line of therapy, three regimens (regorafenib, cabozantinib, and ramucirumab) have been approved for the treatment of aHCC after progression on sorafenib according to guidelines. Furthermore, nivolumab, pembrolizumab, and nivolumab plus ipilimumab have been approved by the FDA (2017, 2018, and 2020, respectively). Finally, immune target therapy, cancer vaccines, and epigenetic drugs represent three new possible weapons for the treatment of HCC.

Epigenetic mechanisms of liver tumor resistance to immunotherapy

Hepatocellular carcinoma (HCC) is the most common primary liver tumor, which stands fourth in rank of cancer-related deaths worldwide. The incidence of HCC is constantly increasing in correlation with the epidemic in diabetes and obesity, arguing for an urgent need for new treatments for this lethal cancer refractory to conventional treatments. HCC is the paradigm of inflammation-associated cancer, since more than 80% of HCC emerge consecutively to cirrhosis associated with a vast remodeling of liver microenvironment. In the recent decade, immunomodulatory drugs have been developed and have given impressive results in melanoma and later in several other cancers. In the present review, we will discuss the recent advancements concerning the use of immunotherapies in HCC, in particular those targeting immune checkpoints, used alone or in combination with other anti-cancers agents. We will address why these drugs demonstrate unsatisfactory results in a high proportion of liver cancers and the mechanisms of resistance developed by HCC to evade immune response with a focus on the epigenetic-related mechanisms.

Relapsed/refractory classical Hodgkin lymphoma effectively treated with low-dose decitabine plus tislelizumab: A case report

BACKGROUND

Academic studies have proved that anti-programmed death-1 (PD-1) monoclonal antibodies demonstrated remarkable activity in relapsed/refractory classical Hodgkin lymphoma (cHL). However, most patients ultimately experienced failure or resistance. It is urgent and necessary to develop a novel strategy for relapsed/refractory cHL. The aim of this case report is to evaluate the combination approach of low-dose decitabine plus a PD-1 inhibitor in relapsed/ refractory cHL patients with prior PD-1 inhibitor exposure.

CASE SUMMARY

The patient was a 27-year-old man who complained of enlarged right-sided cervical lymph nodes and progressive pain aggravation of the right shoulder over the past 3 mo before admission. Histological analysis of lymph node biopsy was suggestive of cHL. The patient experienced failure of eight lines of therapy, including multiple cycles of chemotherapy, PD-1 blockade, and anti-CD47 antibody therapy. Contrast-enhanced CT showed that the tumors of the chest and abdomen significantly shrunk or disappeared after three cycles of treatment with decitabine plus tislelizumab. The patient had been followed for 11.5 mo until March 2, 2021, and no progressive enlargement of the tumor was observed.

CONCLUSION

The strategy of combining low-dose decitabine with tislelizumab could reverse the resistance to PD-1 inhibitors in patients with heavily pretreated relapsed/ refractory cHL. The therapeutic effect of this strategy needs to be further assessed.

Host Epigenetic Alterations and Hepatitis B Virus-Associated Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most frequent primary malignancy of the liver and a leading cause of cancer-related deaths worldwide. Although much progress has been made in HCC drug development in recent years, treatment options remain limited. The major cause of HCC is chronic hepatitis B virus (HBV) infection. Despite the existence of a vaccine, more than 250 million individuals are chronically infected by HBV. Current antiviral therapies can repress viral replication but to date there is no cure for chronic hepatitis B. Of note, inhibition of viral replication reduces but does not eliminate the risk of HCC development. HBV contributes to liver carcinogenesis by direct and indirect effects. This review summarizes the current knowledge of HBV-induced host epigenetic alterations and their association with HCC, with an emphasis on the interactions between HBV proteins and the host cell epigenetic machinery leading to modulation of gene expression.

Low-Dose Decitabine Augments the Activation and Anti-Tumor Immune Response of IFN-γ+ CD4+ T Cells Through Enhancing IκBα Degradation and NF-κB Activation

BACKGROUND

CD4+ T cells play multiple roles in controlling tumor growth and increasing IFN-γ+ T-helper 1 cell population could promote cell-mediated anti-tumor immune response. We have previously showed that low-dose DNA demethylating agent decitabine therapy promotes CD3+ T-cell proliferation and cytotoxicity; however, direct regulation of purified CD4+ T cells and the underlying mechanisms remain unclear.

METHODS

The effects of low-dose decitabine on sorted CD4+ T cells were detected both in vitro and in vivo. The activation, proliferation, intracellular cytokine production and cytolysis activity of CD4+ T cells were analyzed by FACS and DELFIA time-resolved fluorescence assays. In vivo ubiquitination assay was performed to assess protein degradation. Moreover, phosphor-p65 and IκBα levels were detected in sorted CD4+ T cells from solid tumor patients with decitabine-based therapy.

RESULTS

Low-dose decitabine treatment promoted the proliferation and activation of sorted CD4+ T cells, with increased frequency of IFN-γ+ Th1 subset and enhanced cytolytic activity in vitro and in vivo. NF-κB inhibitor, BAY 11-7082, suppressed decitabine-induced CD4+ T cell proliferation and IFN-γ production. In terms of mechanism, low-dose decitabine augmented the expression of E3 ligase β-TrCP, promoted the ubiquitination and degradation of IκBα and resulted in NF-κB activation. Notably, we observed that in vitro low-dose decitabine treatment induced NF-κB activation in CD4+ T cells from patients with a response to decitabine-primed chemotherapy rather than those without a response.

CONCLUSION

These data suggest that low-dose decitabine potentiates CD4+ T cell anti-tumor immunity through enhancing IκBα degradation and therefore NF-κB activation and IFN-γ production.

Epigenetic Biomarkers for the Diagnosis and Treatment of Liver Disease

Research in the last decades has demonstrated the relevance of epigenetics in controlling gene expression to maintain cell homeostasis, and the important role played by epigenome alterations in disease development. Moreover, the reversibility of epigenetic marks can be harnessed as a therapeutic strategy, and epigenetic marks can be used as diagnosis biomarkers. Epigenetic alterations in DNA methylation, histone post-translational modifications (PTMs), and non-coding RNA (ncRNA) expression have been associated with the process of hepatocarcinogenesis. Here, we summarize epigenetic alterations involved in the pathogenesis of chronic liver disease (CLD), particularly focusing on DNA methylation. We also discuss their utility as epigenetic biomarkers in liquid biopsy for the diagnosis and prognosis of hepatocellular carcinoma (HCC). Finally, we discuss the potential of epigenetic therapeutic strategies for HCC treatment.

Updates on the Diagnosis and Management of Hepatocellular Carcinoma

Introduction

Globally, the incidence, as well as mortality, related to hepatocellular carcinoma (HCC) is on the rise, owing to relatively few curative options. Underlying cirrhosis is the most common etiology leading to HCC, but risk factors of cirrhosis show great regional variability. Over the years, there has been a steady development in the diagnostic and therapeutic modalities of HCC, including the availability of a wide range of systemic chemotherapeutic agents. We aim to review the recent advancements in the diagnostic and therapeutic strategies for HCC.

Methodology

The literature search was done using databases PubMed, Cochrane, and Science Direct, and the latest relevant articles were reviewed.

Findings

Screening of HCC is a pivotal step in the early diagnosis of the disease. Current guidelines recommend using ultrasound and alfa fetoprotein but various new biomarkers are under active research that might aid in diagnosing very small tumors, not picked up by the current screening methods. Treatment options are decided based upon the overall performance of the patient and the extent of the disease, as per the Barcelona classification. There are very few options that offer a cure for the disease, ranging from liver resection and transplantation to tumor ablation. Downstaging has proven to have a significant role in the course of the disease. An attempt to control the disease can be made via radiological interventions, such as transarterial chemoembolization, transarterial radioembolization, or radiation therapy. For advanced disease, sorafenib used to be the only option until a couple of years ago. Recently, many other systemic agents have received approval as first-line and second-line therapies for HCC. Genomics is an area of active clinical research as understanding the mutations and genomics involved in the evolution of HCC might lead to a breakthrough therapy.

How to cite this article

Raees A, Kamran M, Özkan H, et al. Updates on the Diagnosis and Management of Hepatocellular Carcinoma. Euroasian J Hepato-Gastroenterol 2021;11(1):32–40.

Hepigenetics: A Review of Epigenetic Modulators and Potential Therapies in Hepatocellular Carcinoma

Hepatocellular carcinoma is the fifth most common cancer worldwide and the second most lethal, following lung cancer. Currently applied therapeutic practices rely on surgical resection, chemotherapy and radiotherapy, or a combination thereof. These treatment options are associated with extreme adversities, and risk/benefit ratios do not always work in patients' favor. Anomalies of the epigenome lie at the epicenter of aberrant molecular mechanisms by which the disease develops and progresses. Modulation of these anomalous events poses a promising prospect for alternative treatment options, with an abundance of felicitous results reported in recent years. Herein, the most recent epigenetic modulators in hepatocellular carcinoma are recapitulated on.

Epigenetics in hepatocellular carcinoma development and therapy: The tip of the iceberg

Hepatocellular carcinoma (HCC) is a deadly tumour whose causative agents are generally well known, but whose pathogenesis remains poorly understood. Nevertheless, key genetic alterations are emerging from a heterogeneous molecular landscape, providing information on the tumorigenic process from initiation to progression. Among these molecular alterations, those that affect epigenetic processes are increasingly recognised as contributing to carcinogenesis from preneoplastic stages. The epigenetic machinery regulates gene expression through intertwined and partially characterised circuits involving chromatin remodelers, covalent DNA and histone modifications, and dedicated proteins reading these modifications. In this review, we summarise recent findings on HCC epigenetics, focusing mainly on changes in DNA and histone modifications and their carcinogenic implications. We also discuss the potential drugs that target epigenetic mechanisms for HCC treatment, either alone or in combination with current therapies, including immunotherapies.

Low-dose DNA demethylating therapy induces reprogramming of diverse cancer-related pathways at the single-cell level

BACKGROUND

Epigenetic reprogramming using DNA demethylating drugs is a promising approach for cancer therapy, but its efficacy is highly dependent on the dosing regimen. Low-dose treatment for a prolonged period shows a remarkable therapeutic efficacy, despite its small demethylating effect. Here, we aimed to explore the mechanisms of how such low-dose treatment shows this remarkable efficacy by focusing on epigenetic reprograming at the single-cell level.

METHODS

Expression profiles in HCT116 cells treated with decitabine (DAC) were analyzed by single-cell RNA-sequencing (scRNA-seq). Functional consequences and DNA demethylation at the single-cell level were analyzed using cloned HCT116 cells after DAC treatment.

RESULTS

scRNA-seq revealed that DAC-treated cells had highly diverse expression profiles at the single-cell level, and tumor-suppressor genes, endogenous retroviruses, and interferon-stimulated genes were upregulated in random fractions of cells. DNA methylation analysis of cloned HCT116 cells revealed that, while only partial reduction of DNA methylation levels was observed in bulk cells, complete demethylation of specific cancer-related genes, such as cell cycle regulation, WNT pathway, p53 pathway, and TGF-β pathway, was observed, depending upon clones. Functionally, a clone with complete demethylation of CDKN2A (p16) had a larger fraction of cells with tetraploid than parental cells, indicating induction of cellular senescence due to normalization of cell cycle regulation.

CONCLUSIONS

Epigenetic reprogramming of specific cancer-related pathways at the single-cell level is likely to underlie the remarkable efficacy of low-dose DNA demethylating therapy.

Recent progress in treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death worldwide. In the past decade, there have been improvements in non-drug therapies and drug therapies for HCC treatment. Non-drug therapies include hepatic resection, liver transplantation, transarterial chemoembolization (TACE) and ablation. The former two surgical treatments are beneficial for patients with early and mid-stage HCC. As the first choice for non-surgical treatment, different TACE methods has been developed and widely used in combination therapy. Ablation has become an important alternative therapy for the treatment of small HCC or cases of unresectable surgery. Meanwhile, the drugs including small molecule targeted drugs like sorafenib and lenvatinib, monoclonal antibodies such as nivolumab are mainly used for the systematic treatment of advanced HCC. Besides strategies described above are recommended as first-line therapies due to their significant increase in mean overall survival, there are also potential drugs in clinical trials or under preclinical development. In addition, a number of potential preclinical surgical or adjuvant therapies are being studied, such as oncolytic virus, mesenchymal stem cells, biological clock, gut microbiome composition and peptide vaccine, all of which have shown different degrees of inhibition on HCC. With some potential anti-HCC drugs being reported, many promising therapeutic targets in related taxonomic signaling pathways including cell cycle, epigenetics, tyrosine kinase and so on that affect the progression of HCC have also been found. Together, the rational application of existing therapies and drugs as well as the new strategies will bring a bright future for the global cure of HCC in the coming decades.

A novel strategy for the diagnosis, prognosis, treatment, and chemoresistance of hepatocellular carcinoma: DNA methylation

The cancer mortality rate of hepatocellular carcinoma (HCC) is the second highest in the world and the therapeutic options are limited. The incidence of this deadly cancer is rising at an alarming rate because of the high degree of resistance to chemo- and radiotherapy, lack of proper, and adequate vaccination to hepatitis B, and lack of consciousness and knowledge about the disease itself and the lifestyle of the people. DNA methylation and DNA methylation-induced epigenetic alterations, due to their potential reversibility, open the access to develop novel biomarkers and therapeutics for HCC. The contribution to these epigenetic changes in HCC development still has not been thoroughly summarized. Thus, it is necessary to better understand the new molecular targets of HCC epigenetics in HCC diagnosis, prevention, and treatment. This review elaborates on recent key findings regarding molecular biomarkers for HCC early diagnosis, prognosis, and treatment. Currently emerging epigenetic drugs for the treatment of HCC are summarized. In addition, combining epigenetic drugs with nonepigenetic drugs for HCC treatment is also mentioned. The molecular mechanisms of DNA methylation-mediated HCC resistance are reviewed, providing some insights into the difficulty of treating liver cancer and anticancer drug development.

Modulation of the Endothelin System in Colorectal Cancer Liver Metastasis: Influence of Epigenetic Mechanisms?

Targeting of endothelin system genes is a promising strategy in cancer therapy. The modulation of these genes was explored in a model of colorectal cancer (CRC) liver metastasis and in a panel of CRC tumor cell lines that were exposed to the demethylating agent decitabine. The CC531 rat model mimicking CRC liver metastasis was used for tumor cell re-isolation and analysis of the endothelin system genes and DNA methyltransferases (DNMTs) by microarray. To mimic the effects caused by methylation changes, a panel of seven CRC cell lines was treated with the demethylating agent decitabine. Three genes of the endothelin system were potently modulated at messenger RNA (mRNA) level in rat CC531 cells during liver colonization. The concomitant decrease of two DNMTs suggested an influence from altered methylation. Changes in gene expression were also accomplished by exposure of CRC cells to the demethylating agent decitabine, when using daily low concentrations for 3 days, with minimal cytotoxic effects. Sensitive human SW480 cells showed an almost 100fold upregulation of endothelin-1 mRNA compared to untreated cells. This, however, was different in LS174T cells, which showed no significant increase in gene expression although the methylation levels were significantly decreased at a variety of corresponding loci. We suggest that the mechanism induced by methylation on gene expression in metastatic CRC cells can be compromised. The results question the overall success of treating metastatic CRC by methylation inhibitors.

Tackling hepatocellular carcinoma with individual or combinatorial immunotherapy approaches

Hepatocellular carcinoma (HCC) is the third leading cause of death from cancer globally. Indeed, there is a single drug approved as first-line systemic therapy in advanced unresectable HCC, providing a very limited survival benefit. In earlier stages, 5-year survival rates after surgical and loco-regional therapies are extremely variable depending on the stage of disease. Nevertheless, HCC is considered an immunogenic tumor arising in chronically inflamed livers. In such a scenario, immunotherapy strategies for HCC, in particular combinations including cancer vaccines, may represent a key therapeutic tool to improve clinical outcome in HCC patients. However, a lot of improvement is needed given the disappointing results obtained so far.

Development and validation of a CIMP-associated prognostic model for hepatocellular carcinoma

Background

CpG island methylator phenotype (CIMP), a common biological phenomenon characterized by a subset of concurrently methylated genes, can have an influence on the progression of multiple cancers. However, the potential mechanism of CIMP in hepatocarcinogenesis and its clinical relevance remains only partially understood.

Methods: We used a methylation array from the cancer genome atlas (TCGA) to stratify HCC patients into different CIMP subtypes, and evaluated their correlation with clinical characteristics. In addition, mutation, CNV, and transcriptome profiles were also utilized to evaluate the distinctive genomic patterns correlated with CIMP. Finally, a CIMP-associated prognostic model (CPM) was trained and validated using four independent datasets.

Findings

A subgroup of patients was identified as having CIMP-H, which was associated with worse OS and DFS. Gene enrichment analysis indicated that the terms “liver cancer with EPCAM up”, “tumor invasiveness up”, “methyltransferase complex”, and “translational initiation” were enriched in CIMP-H subgroup. Notably, somatic mutation analysis indicated that CIMP-H patients presented with a higher mutation burden of BRD4, DDIAS and NOX1. Moreover, four CPM associated genes could significantly categorize patients into low- and high-risk groups in the training dataset and another 3 independent validation datasets. Finally, a nomogram incorporating a classifier based on four mRNAs, pathological M stage and CIMP status was established, which showed a favorable discriminating ability and might contribute to clinical decision-making for HCC.

Interpretation

Our work highlights the potential clinical application value of CPM in predicting the overall survival of HCC patients and the mechanisms underlying the role of CIMP in hepatocarcinogenesis.

Fund

This work was supported by the State Key Project on Infectious Diseases of China (2018ZX10723204-003), the National Nature Science Foundation of China (Nos. 81874065, 81500565, 81874149, 81572427, and 81401997), the Hepato-Biliary-Pancreatic Malignant Tumor Investigation Fund of Chen Xiao-ping Foundation for the Development of Science and Technology of Hubei Province (CXPJJH11800001-2018356).

Epigenetics of hepatocellular carcinoma

In recent years, large scale genomics and genome-wide studies using comprehensive genomic tools have reshaped our understanding of cancer evolution and heterogeneity. Hepatocellular carcinoma, being one of the most deadly cancers in the world has been well established as a disease of the genome that harbours a multitude of genetic and epigenetic aberrations during the process of liver carcinogenesis. As such, in depth understanding of the cancer epigenetics in cancer specimens and biopsy can be useful in clinical settings for molecular subclassification, prognosis, and prediction of therapeutic responses. In this review, we present a concise discussion on recent progress in the field of liver cancer epigenetics and some of the current works that contribute to the progress of liver cancer therapeutics.

Addition of Low-Dose Decitabine to Anti-PD-1 Antibody Camrelizumab in Relapsed/Refractory Classical Hodgkin Lymphoma

PURPOSE

Anti-programmed death-1 (PD-1) monotherapy induces a high response rate in patients with relapsed/refractory classic Hodgkin lymphoma (cHL), but complete remission (CR) is infrequently observed. As decitabine is known to boost T-cell function, we assessed the safety and efficacy of anti-PD-1 camrelizumab alone versus decitabine-primed camrelizumab in patients with relapsed/refractory cHL.

METHODS

This two-arm, open-label, phase II study enrolled patients with relapsed/refractory cHL who had received at least two lines of previous therapy. Anti-PD-1 treatment-naïve patients were randomly assigned (1:2) to camrelizumab (200 mg) monotherapy or decitabine (10 mg/d, days 1 to 5) plus camrelizumab (200 mg, day 8) combination therapy every 3 weeks. Patients who were previously treated with anti-PD-1 were assigned combination therapy. Primary end point was CR rate and safety.

RESULTS

Overall, 86 patients were enrolled and evaluated for response, with a median follow-up of 14.9 months. In anti-PD-1-naïve patients, CR rate was 32% (six of 19 patients) with camrelizumab monotherapy versus 71% (30 of 42 patients) who were administered decitabine plus camrelizumab (P = .003). At the time of analysis, the response duration rate at 6 months was 76% on camrelizumab monotherapy versus 100% on decitabine plus camrelizumab. For patients who were previously treated with anti-PD-1, 28% achieved CR and 24% partial response after decitabine plus camrelizumab. Ten patients maintained a response at more than 6 months and 81% of responders were estimated to have a response at more than 1 year. For both treatments, the most common adverse events were clinically inconsequential cherry hemangiomas and leukocytopenia that were self-limiting.

CONCLUSION

CR rate in patients with relapsed/refractory cHL who were clinically naïve to PD-1 blockade was significantly higher with decitabine plus camrelizumab than with camrelizumab alone. Decitabine plus camrelizumab may reverse resistance to PD-1 inhibitors in patients with relapsed/refractory cHL.

Phase Ib/II study of safety and efficacy of low-dose decitabine-primed chemoimmunotherapy in patients with drug-resistant relapsed/refractory alimentary tract cancer

The pressing need for improved therapeutic outcomes provides a good rationale for identifying effective strategies for alimentary tract (AT) cancer treatment. The potential re-sensitivity property to chemo- and immunotherapy of low-dose decitabine has been evident both preclinically and in previous phase I trials. We conducted a phase Ib/II trial evaluating low-dose decitabine-primed chemoimmunotherapy in patients with drug-resistant relapsed/refractory (R/R) esophageal, gastric or colorectal cancers. Forty-five patients received either the 5-day decitabine treatment with subsequent readministration of the previously resistant chemotherapy (decitabine-primed chemotherapy, D-C cohort) or the aforementioned regimen followed by cytokine-induced killer cells therapy (D-C and cytokine-induced killer [CIK] cell treatment, D-C + CIK cohort) based on their treatment history. Grade 3 to 4 adverse events (AEs) were reported in 11 (24.4%) of 45 patients. All AEs were controllable, and no patient experienced a treatment-related death. The objective response rate (ORR) and disease control rate (DCR) were 24.44% and 82.22%, respectively, including two patients who achieved durable complete responses. Clinical response could be associated with treatment-free interval and initial surgical resection history. ORR and DCR reached 28% and 92%, respectively, in the D-C + CIK cohort. Consistently, the progression-free survival (PFS) of the D-C + CIK cohort compared favorably to the best PFS of the pre-resistant unprimed therapy (p = 0.0001). The toxicity and ORRs exhibited were non-significantly different between cancer types and treatment cohort. The safety and efficacy of decitabine-primed re-sensitization to chemoimmunotherapy is attractive and promising. These data warrant further large-scale evaluation of drug-resistant R/R AT cancer patients with advanced stage disease.

Resistance a major hindrance to chemotherapy in hepatocellular carcinoma: an insight

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer mortality, accounting for almost 90% of total liver cancer burden. Surgical resection followed by adjuvant and systemic chemotherapy are the most meticulously followed treatment procedures but the complex etiology and high metastatic potential of the disease renders surgical treatment futile in majority of the cases. Another hindrance to the scenario is the acquired resistance to drugs resulting in relapse of the disease. Hence, to provide insights into development of novel therapeutic targets and diagnostic biomarkers, this review focuses on the various molecular mechanisms underlying chemoresistance in HCC. We have provided a comprehensive summary of the various strategies adopted by HCC cells, extending from apoptosis evasion, autophagy activation, drug expulsion to epigenetic transformation as modes of therapy resistance. The role of stem cells in imparting chemoresistance is also discussed. Furthermore, the review also focuses on how this knowledge might be exploited for the development of an effective, prospective therapy against HCC.

Clinical and biological significance of miR-23b and miR-193a in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common cancer of the liver with a very poor prognosis. The dysregulation of microRNAs (miRs) is indeed implicated in HCC onset and progression. In this study, we have evaluated the expression of miR-23b and miR-193a in a large cohort of 59 and 67 HCC patients, respectively. miR-23b and miR-193a resulted significantly down-regulated in primary HCCs compared to their matched peritumoral counterparts. Furthermore, patients with higher miR-193a expression exhibited longer OS and DFS, suggesting that miR-193a may be a molecular prognostic factor for HCC patients. Since the regulation of miRs by DNA methylation may occur in human cancers, we verified whether the down-modulation of miR-23b and miR-193a in HCC tissues could be related to DNA methylation. An inverse trend between miR-23b expression and DNA methylation was observed, indicating that miR-23b can be epigenetically regulated. By contrast, the down-regulation of miR-193a was not mediated by DNA methylation. To verify the potential role of miR-23b and miR-193a as responsive molecular targets in vitro, we used the inhibitor of DNA methylation 5-aza-dC to restore miR-23b expression level in combination with miR-193a transfection. The combined treatment led to a significant inhibition of cellular proliferation and migration. Taken together, our findings provide evidence that miR-23b and miR-193a may be molecular diagnostic and prognostic factors for HCC; furthermore, miR-23b and miR-193a are responsive molecular targets for limiting HCC cell aggressiveness in combination with the epigenetic drug 5-aza-dC. Moreover, our results provide new advances in the epigenetic regulation of these miRs in HCC.

Waking up dormant tumor suppressor genes with zinc fingers, TALEs and the CRISPR/dCas9 system

The aberrant epigenetic silencing of tumor suppressor genes (TSGs) plays a major role during carcinogenesis and regaining these dormant functions by engineering of sequence-specific epigenome editing tools offers a unique opportunity for targeted therapies. However, effectively normalizing the expression and regaining tumor suppressive functions of silenced TSGs by artificial transcription factors (ATFs) still remains a major challenge. Herein we describe novel combinatorial strategies for the potent reactivation of two class II TSGs, MASPIN and REPRIMO, in cell lines with varying epigenetic states, using the CRISPR/dCas9 associated system linked to a panel of effector domains (VP64, p300, VPR and SAM complex), as well as with protein-based ATFs, Zinc Fingers and TALEs. We found that co-delivery of multiple effector domains using a combination of CRISPR/dCas9 and TALEs or SAM complex maximized activation in highly methylated promoters. In particular, CRISPR/dCas9 VPR with SAM upregulated MASPIN mRNA (22,145-fold change) in H157 lung cancer cells, with accompanying re-expression of MASPIN protein, which led to a concomitant inhibition of cell proliferation and induction of apoptotic cell death. Consistently, CRISPR/dCas9 VP64 with SAM upregulated REPRIMO (680-fold change), which led to phenotypic reprogramming in AGS gastric cancer cells. Altogether, our results outlined novel sequence-specific, combinatorial epigenome editing approaches to reactivate highly methylated TSGs as a promising therapy for cancer and other diseases.

DNA demethylating agent decitabine broadens the peripheral T cell receptor repertoire

Purpose

Decitabine, a promising epi-immunotherapeutic agent has shown clinical responses in solid tumor patients, while the anti-tumor mechanisms were unclear. We aimed to investigate the immunomodulatory effect of decitabine in peripheral T cells.

Experimental design

We applied next-generation sequencing to investigate the complementarity-determining region 3 (CDR3) of the TCRβ gene, the diversity of which acts as the prerequisite for the host immune system to recognize the universal foreign antigens. We collected the peripheral blood mononuclear cells (PBMCs) from 4 patients, at baseline and after 2 cycles of low-dose decitabine therapy.

Results

An increase of the unique productive sequences of the CDR3 of TCRβ was observed in all of the 4 patients after decitabine treatment, which was characterized by a lower abundance of expanded clones and increased TCR diversity compared with before decitabine treatment. Further analysis showed a tendency for CD4 T cells with an increased CD4/CD8 ratio in response to decitabine therapy. In addition, the genome-wide expression alterations confirmed the effects of decitabine on immune reconstitution, and the increase of TCR excision circles (TRECs) was validated.

Conclusions

The low-dose DNMT inhibitor decitabine broadens the peripheral T cell repertoire, providing a novel role for the epigenetic modifying agent in anti-tumor immune enhancement.

GATA4 loss of function in liver cancer impedes precursor to hepatocyte transition

The most frequent chromosomal structural loss in hepatocellular carcinoma (HCC) is of the short arm of chromosome 8 (8p). Genes on the remaining homologous chromosome, however, are not recurrently mutated, and the identity of key 8p tumor-suppressor genes (TSG) is unknown. In this work, analysis of minimal commonly deleted 8p segments to identify candidate TSG implicated GATA4, a master transcription factor driver of hepatocyte epithelial lineage fate. In a murine model, liver-conditional deletion of 1 Gata4 allele to model the haploinsufficiency seen in HCC produced enlarged livers with a gene expression profile of persistent precursor proliferation and failed hepatocyte epithelial differentiation. HCC mimicked this gene expression profile, even in cases that were morphologically classified as well differentiated. HCC with intact chromosome 8p also featured GATA4 loss of function via GATA4 germline mutations that abrogated GATA4 interactions with a coactivator, MED12, or by inactivating mutations directly in GATA4 coactivators, including ARID1A. GATA4 reintroduction into GATA4-haploinsufficient HCC cells or ARID1A reintroduction into ARID1A-mutant/GATA4-intact HCC cells activated hundreds of hepatocyte genes and quenched the proliferative precursor program. Thus, disruption of GATA4-mediated transactivation in HCC suppresses hepatocyte epithelial differentiation to sustain replicative precursor phenotype.

Increased IFNγ+ T Cells Are Responsible for the Clinical Responses of Low-Dose DNA-Demethylating Agent Decitabine Antitumor Therapy

Purpose: Low-dose DNA-demethylating agent decitabine therapy is effective in a subgroup of cancer patients. It remains largely elusive for the biomarker to predict therapeutic response and the underlying antitumor mechanisms, especially the impact on host antitumor immunity.Experimental Design: The influence of low-dose decitabine on T cells was detected both in vitro and in vivo Moreover, a test cohort and a validation cohort of advanced solid tumor patients with low-dose decitabine-based treatment were involved. The activation, proliferation, polarization, and cytolysis capacity of CD3⁺ T cells were analyzed by FACS and CCK8 assay. Kaplan-Meier and Cox proportional hazard regression analysis were performed to investigate the prognostic value of enhanced T-cell activity following decitabine epigenetic therapy.Results: Low-dose decitabine therapy enhanced the activation and proliferation of human IFNγ⁺ T cells, promoted Th1 polarization and activity of cytotoxic T cells both in vivo and in vitro, which in turn inhibited cancer progression and augmented the clinical effects of patients. In clinical trials, increased IFNγ⁺ T cells and increased T-cell cytotoxicity predicted improved therapeutic responses and survival in the test cohort and validation cohort.Conclusions: We find that low-dose decitabine therapy promotes antitumor T-cell responses by promoting T-cell proliferation and the increased IFNγ⁺ T cells may act as a potential prognostic biomarker for the response to decitabine-based antitumor therapy. Clin Cancer Res; 23(20); 6031-43. ©2017 AACR.

The safety, efficacy, and treatment outcomes of a combination of low-dose decitabine treatment in patients with recurrent ovarian cancer

Purpose: DNA demethylating agents have shown clinical effectiveness in hematological and solid tumors. This trial tested the safety, efficacy, and treatment outcomes of decitabine-based chemotherapy or combined with immunotherapy in recurrent ovarian cancer patients. Patients and methods: Fifty-five patients with recurrent ovarian cancer were enrolled and 52 were assessable for clinical response and survival. Patients either received 5-d decitabine treatment, followed by reduced-dose of paclitaxel/carboplatin administration (DTC cohort), or the aforementioned regimen combined with cytokine-induced killer cells therapy (DTC+CIK cohort). The primary end point was clinical response rate and progression-free survival (PFS). Secondary evaluation included safety assessment and overall survival (OS). Results: Disease control rate (DCR) and objective response rate (ORR) were 73.91% and 23.91% in disease measurable patients by RECIST criteria, totally 76.92% and 30.77%, including disease non-measurable patients, which were higher in platinum-resistant/refractory patients. Clinical benefits could be associated with the number of DAC treatment cycles and the inclusion of CIK immunotherapy. In DTC+CIK cohort, DCR and ORR reached 100% and 58.30%, respectively. Notably, DTC+CIK treatment in platinum-resistant/refractory patients had an ORR of 87.50%. Consistently, PFS was longer in platinum-resistant/refractory patients comparing with that of platinum-sensitive patients. PFS and OS were 8 and 19 mo in platinum-resistant/refractory patients with DTC+CIK therapy. The most common toxicities were nausea, anorexia, fatigue, neutropenia, and anemia; many of which were grade 1-2. Conclusion: Low-dose DAC/paclitaxel/carboplatin regimen demonstrates disease benefit, especially in patients with platinum-resistant/refractory ovarian cancer, and might show remarkable clinical response when combined with adoptive immunotherapy in platinum-resistant/refractory ovarian cancer patients.

Hepatoepigenetic Alterations in Viral and Nonviral-Induced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a major public health concern and one of the leading causes of tumour-related deaths worldwide. Extensive evidence endorses that HCC is a multifactorial disease characterised by hepatic cirrhosis mostly associated with chronic inflammation and hepatitis B/C viral infections. Interaction of viral products with the host cell machinery may lead to increased frequency of genetic and epigenetic aberrations that cause harmful alterations in gene transcription. This may provide a progressive selective advantage for neoplastic transformation of hepatocytes associated with phenotypic heterogeneity of intratumour HCC cells, thus posing even more challenges in HCC treatment development. Epigenetic aberrations involving DNA methylation, histone modifications, and noncoding miRNA dysregulation have been shown to be intimately linked with and play a critical role in tumour initiation, progression, and metastases. The current review focuses on the aberrant hepatoepigenetics events that play important roles in hepatocarcinogenesis and their utilities in the development of HCC therapy.