Hepatocellular carcinoma: Therapeutic advances in signaling,epigenetic and immune targets

Hepatocellular carcinoma(HCC)remains a global medical burden with rising incidence due to chronic viral hepatitis and non-alcoholic fatty liver diseases.Treatment of advanced disease stages is still unsatisfying.Besides first and second generation tyrosine kinase inhibitors,immune checkpoint inhibitors have become central for the treatment of HCC.New modalities like epigenetic therapy using histone deacetylase inhibitors(HDACi)and cell therapy approaches with chimeric antigen receptor T cells(CAR-T cells)are currently under investigation in clinical trials.Development of such novel drugs is closely linked to the availability and improvement of novel preclinical and animal models and the identification of predictive biomarkers.The current status of treatment options for advanced HCC,emerging novel therapeutic approaches and different preclinical models for HCC drug discovery and development are reviewed here.

Epigenetics and pancreatic cancer:Pathophysiology and novel treatment aspects

An improvement in pancreatic cancer treatment represents an urgent medical goal.Late diagnosis and high intrinsic resistance to conventional chemotherapy has led to a dismal overall prognosis that has remained unchanged during the past decades.Increasing knowledge about the molecular pathogenesis of the disease has shown that genetic alterations,such as mutations of K-ras,and especially epigenetic dysregulation of tumor-associated genes,such as silencing of the tumor suppressor p16ink4a,are hallmarks of pancreatic cancer.Here,we describe genes that are commonly affected by epigenetic dysregulation in pancreatic cancer via DNA methylation,histone acetylation or miRNA(microRNA)expression,and review the implications on pancreatic cancer biology such as epithelial-mesenchymal transition,morphological pattern formation,or cancer stem cell regulation during carcinogenesis from PanIN(pancreatic intraepithelial lesions)to invasive cancer and resistance development.Epigenetic drugs,such as DNA methyltransferases or histone deactylase inhibitors,have shown promising preclinical results in pancreatic cancer and are currently in early phases of clinical development.Combinations of epigenetic drugs with established cytotoxic drugs or targeted therapies are promising approaches to improve the poor response and survival rate of pancreatic cancer patients.

How to establish endoscopic submucosal dissection in Western countries

Endoscopic submucosal dissection(ESD) has been invented in Japan to provide resection for cure of early cancer in the gastrointestinal tract. Professional level of ESD requires excellent staging of early neoplasias with image enhanced endoscopy(IEE) to make correct indications for ESD,and high skills in endoscopic electrosurgical dissection. In Japan,endodiagnostic and endosurgical excellence spread through personal tutoring of skilled endoscopists by the inventors and experts in IEE and ESD. To translocate this expertise to other continents must overcome two fundamental obstacles:(1) inadequate expectations as to the complexity of IEE and ESD; and(2) lack of suitable lesions and master-mentors for ESD trainees. Leading endoscopic mucosal resection-proficient endoscopists must pioneer themselves through the long learning curve to proficient ESD experts. Major referral centers for ESD must arise in Western countries on comparable professional level as in Japan. In the second stage,the upcoming Western experts must commit themselves to teach skilled endoscopists from other referral centers,in order to spread ESD in Western countries. Respect for patients with early gastrointestinal cancer asks for best efforts to learn endoscopic categorization of early neoplasias and skills for ESD based on sustained cooperation with the masters in Japan. The strategy is discussed here.

Differential role of Hedgehog signaling in human pancreatic(patho-)physiology:An up to date review

Since the discovery of the Hedgehog(Hh)pathway in drosophila melanogaster,our knowledge of the role of Hh in embryonic development,inflammation,and cancerogenesis in humans has dramatically increased over the last decades.This is the case especially concerning the pancreas,however,real therapeutic breakthroughs are missing until now.In general,Hh signaling is essential for pancreatic organogenesis,development,and tissue maturation.In the case of acute pancreatitis,Hh has a protective role,whereas in chronic pancreatitis,Hh interacts with pancreatic stellate cells,leading to destructive parenchym fibrosis and atrophy,as well as to irregular tissue remodeling with potency of initiating cancerogenesis.In vitro and in situ analysis of Hh in pancreatic cancer revealed that the Hh pathway participates in the development of pancreatic precursor lesions and ductal adenocarcinoma including critical interactions with the tumor microenvironment.The application of specific inhibitors of components of the Hh pathway is currently subject of ongoing clinical trials(phases 1 and 2).Furthermore,a combination of Hh pathway inhibitors and established chemotherapeutic drugs could also represent a promising therapeutic approach.In this review,we give a structured survey of the role of the Hh pathway in pancreatic development,pancreatitis,pancreatic carcinogenesis and pancreatic cancer as well as an overview of current clinical trials concerning Hh pathway inhibitors and pancreas cancer.

Role of histone deacetylases in pancreas: Implications for pathogenesis and therapy

In the last years, our knowledge of the pathogenesis in acute and chronic pancreatitis(AP/CP) as well as in pancreatic cancerogenesis has significantly diversified. Nevertheless, the medicinal therapeutic options are still limited and therapeutic success and patient outcome are poor. Epigenetic deregulation of gene expression is known to contribute to development and progression of AP and CP as well as of pancreatic cancer. Therefore, the selective inhibition of aberrantly active epigenetic regulators can be an effective option for future thera-pies. Histone deacetylases(HDACs) are enzymes that remove an acetyl group from histone tails, thereby causing chromatin compaction and repression of transcri-ption. In this review we present an overview of the currently available literature addressing the role of HDACs in the pancreas and in pancreatic diseases. In pancreatic cancerogenesis, HDACs play a role in the important process of epithelial-mesenchymal-transition, ubiquitin-proteasome pathway and, hypoxia-inducible-factor-1-angiogenesis. Finally, we focus on HDACs as potential therapeutic targets by summarizing currently available histone deacetylase inhibitors.

Biliary tract cancer stem cells-translational options and challenges

Management of biliary tract cancer remains challenging. Tumors show high recurrence rates and therapeutic resistance, leading to dismal prognosis and short survival. The cancer stem cell model states that a tumor is a heterogeneous conglomerate of cells, in which a certain subpopulation of cells-the cancer stem cells-possesses stem cell properties. Cancer stem cells have high clinical relevance due to their potential contributions to development, progression and aggressiveness as well as recurrence and metastasis of malignant tumors. Consequently, reliable identification of as well as pharmacological intervention with cancer stem cells is an intensively investigated and promising research field. The involvement of cancer stem cells in biliary tract cancer is likely as a number of studies demonstrated their existence and the obvious clinical relevance of several established cancer stem cell markers in biliary tract cancer models and tissues. In the present article, we review and discuss the currently available literature addressing the role of putative cancer stem cells in biliary tract cancer as well as the connection between known contributors of biliary tract tumorigenesis such as oncogenic signaling pathways, micro-RNAs and the tumor microenvironment with cancer stem cells.