Phase II study of sirolimus in treatment-naive patients with advanced hepatocellular carcinoma

Insights in Molecular Therapies for Hepatocellular Carcinoma

We conducted a comprehensive review of the current literature of published data and clinical trials (MEDLINE), as well as published congress contributions and active recruiting clinical trials on targeted therapies in hepatocellular carcinoma. Combinations of different agents and medical therapy along with radiological interventions were analyzed for the setting of advanced HCC. Those settings were also analyzed in combination with adjuvant situations after resection or radiological treatments. We summarized the current knowledge for each therapeutic setting and combination that currently is or has been under clinical evaluation. We further discuss the results in the background of current treatment guidelines. In addition, we review the pathophysiological mechanisms and pathways for each of these investigated targets and drugs to further elucidate the molecular background and underlying mechanisms of action. Established and recommended targeted treatment options that already exist for patients are considered for systemic treatment: atezolizumab/bevacizumab, durvalumab/tremelimumab, sorafenib, lenvatinib, cabozantinib, regorafenib, and ramucirumab. Combination treatment for systemic treatment and local ablative treatment or transarterial chemoembolization and adjuvant and neoadjuvant treatment strategies are under clinical investigation.

Autophagy: A challengeable paradox in cancer treatment

OBJECTIVE

Autophagy is an intracellular degradation pathway conserved in all eukaryotes from yeast to humans. This process plays a quality-control role by destroying harmful cellular components under normal conditions, maintaining cell survival, and establishing cellular adaptation under stressful conditions. Hence, there are various studies indicating dysfunctional autophagy as a factor involved in the development and progression of various human diseases, including cancer. In addition, the importance of autophagy in the development of cancer has been highlighted by paradoxical roles, as a cytoprotective and cytotoxic mechanism. Despite extensive research in the field of cancer, there are many questions and challenges about the roles and effects suggested for autophagy in cancer treatment. The aim of this study was to provide an overview of the paradoxical roles of autophagy in different tumors and related cancer treatment options.

METHODS

In this study, to find articles, a search was made in PubMed and Google scholar databases with the keywords Autophagy, Autophagy in Cancer Management, and Drug Design.

RESULTS

According to the investigation, some studies suggest that several advanced cancers are dependent on autophagy for cell survival, so when cancer cells are exposed to therapy, autophagy is induced and suppresses the anti-cancer effects of therapeutic agents and also results in cell resistance. However, enhanced autophagy from using anti-cancer drugs causes autophagy-mediated cell death in several cancers. Because autophagy also plays roles in both tumor suppression and promotion further research is needed to determine the precise mechanism of this process in cancer treatment.

CONCLUSION

We concluded in this article, autophagy manipulation may either promote or hinder the growth and development of cancer according to the origin of the cancer cells, the type of cancer, and the behavior of the cancer cells exposed to treatment. Thus, before starting treatment it is necessary to determine the basal levels of autophagy in various cancers.

[The dual mTORC1/2 inhibitor AZD2014 inhibits acute graft rejection in a rat liver transplantation model]

OBJECTIVE

To investigate the inhibitory effect of AZD2014, a dual mTORC1/2 inhibitor, against acute graft rejection in a rat model of allogeneic liver transplantation.

METHODS

Liver transplantation from Lewis rat to recipient BN rat (a donor-recipient combination that was prone to induce acute graft rejection) was performed using Kamada's two-cuff technique. The recipient BN rats were randomized into 2 groups for treatment with daily intraperitoneal injection of AZD2014 (5 mg/kg, n=4) or vehicle (2.5 mL/kg, n=4) for 14 consecutive days, starting from the first day after the transplantation. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) levels of the rats were measured 3 days before and at 1, 3, 5, 7, 10, and 14 days after the transplantation, and the survival time of the rats within 14 days were recorded. Immunohistochemical staining was used to examine the expressions of CD3 and Foxp3 in the liver graft, and acute graft rejection was assessed using HE staining based on the Banff schema.

RESULTS

Three rats in the control group died within 14 days after the surgery, while no death occurred in the AZD2014 group, demonstrating a significantly longer survival time of the rats in AZD2014 group (χ2=4.213, P=0.04). Serum ALT, AST and TBIL levels in the control group increased progressively after the surgery and were all significantly higher than those in AZD2014 group at the same time point (P < 0.05). Pathological examination revealed significantly worse liver graft rejection in the control group than in AZD2014 group based on assessment of the rejection index (P < 0.01); the rats in the control group showed more serious T lymphocyte infiltration and significantly fewer Treg cells in the liver graft than those in AZD2014 group (P < 0.01).

CONCLUSIONS

AZD2014 can effectively inhibit acute graft rejection in rats with allogeneic liver transplantation.

PROX1, a Key Mediator of the Anti-Proliferative Effect of Rapamycin on Hepatocellular Carcinoma Cells

The MTOR signal is known to be activated in various cancer cells including hepatocellular carcinoma (HCC) cells. Rapamycin, a specific inhibitor of MTOR, has been widely used as an immunosuppressant in organ transplant patients, and its clinical application has been recently expanded to cancer therapy. In this study, the anti-proliferative effect of rapamycin was investigated in four different HCC cell lines. Rapamycin effectively inhibited the proliferation of Huh7 or Hep3B, but not that of HepG2 or SNU3160 cells. Interestingly, rapamycin increased Prospero-related homeobox 1 (PROX1) expression at the protein level, but did not affect its transcript in Huh7 as well as Hep3B cells. Moreover, immunoprecipitation assays showed that PROX1 ubiquitination was downregulated by rapamycin. Furthermore, PROX1 over-expression or siRNA knock-down in Huh7 and Hep3B cells reduced or increased proliferation, respectively. The effect of PROX1 over-expression on the sensitivity to rapamycin was not synergistic, but the effect of MTOR inhibition on cell proliferation was diminished by PROX1 siRNA. Finally, Huh7 cells were inoculated into the flanks of nude mice and rapamycin was injected daily for 14 days. The xenograft volume was decreased and PROX1 expression was increased by rapamycin. These results indicate that PROX1 plays a key role in the anti-proliferative effect of rapamycin and suggest that the increased PROX1 by MTOR inhibition can be used as a useful marker for predicting whether HCC cells can be affected by rapamycin.

Antifungal agent Terbinafine restrains tumor growth in preclinical models of hepatocellular carcinoma via AMPK-mTOR axis

The prognosis of hepatocellular carcinoma (HCC) remains unsatisfactory due to limited effective treatment options. In this work, we investigated the therapeutic efficacy of Terbinafine for HCC and the underlying mechanism. The influence of Terbinafine on cell growth, 3D spheroid formation, clonogenic survival, and protein synthesis was investigated in human HCC cell lines. Co-immunoprecipitation, immunofluorescence, and other techniques were employed to explore how Terbinafine exerts its anticancer effect. Subcutaneous tumorigenicity assay, orthotopic and patient-derived xenograft (PDX) HCC models were used to evaluate the anticancer effect of Terbinafine monotherapy and the combinatorial treatment with Terbinafine and sorafenib against HCC. The anticancer activity of Terbinafine was Squalene epoxidase (SQLE)-independent. Instead, Terbinafine robustly suppressed the proliferation of HCC cells by inhibiting mTORC1 signaling via activation of AMPK. Terbinafine alone or in combination with sorafenib delayed tumor progression and markedly prolonged the survival of tumor-bearing mice. The synergy between Terbinafine and sorafenib was due to concomitant inhibition of mTORC1 and induction of severe persistent DNA double-strand breaks (DSBs), which led to the delayed proliferation and accelerated cell death. Terbinafine showed promising anticancer efficacy in preclinical models of HCC and may serve as a potential therapeutic strategy for HCC.

The Pathways Underlying the Multiple Roles of p62 in Inflammation and Cancer

p62 is a highly conserved, multi-domain, and multi-functional adaptor protein critically involved in several important cellular processes. Via its pronounced domain architecture, p62 binds to numerous interaction partners, thereby influencing key pathways that regulate tissue homeostasis, inflammation, and several common diseases including cancer. Via binding of ubiquitin chains, p62 acts in an anti-inflammatory manner as an adaptor for the auto-, xeno-, and mitophagy-dependent degradation of proteins, pathogens, and mitochondria. Furthermore, p62 is a negative regulator of inflammasome complexes. The transcription factor Nrf2 regulates expression of a bundle of ROS detoxifying genes. p62 activates Nrf2 by interaction with and autophagosomal degradation of the Nrf2 inhibitor Keap1. Moreover, p62 activates mTOR, the central kinase of the mTORC1 sensor complex that controls cell proliferation and differentiation. Through different mechanisms, p62 acts as a positive regulator of the transcription factor NF-κB, a central player in inflammation and cancer development. Therefore, p62 represents not only a cargo receptor for autophagy, but also a central signaling hub, linking several important pro- and anti-inflammatory pathways. This review aims to summarize knowledge about the molecular mechanisms underlying the roles of p62 in health and disease. In particular, different types of tumors are characterized by deregulated levels of p62. The elucidation of how p62 contributes to inflammation and cancer progression at the molecular level might promote the development of novel therapeutic strategies.

Research Progresses of Targeted Therapy and Immunotherapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide, with nearly one million new cases and deaths every year. Owing to the complex pathogenesis, hidden early symptoms, rapidly developing processes, and poor prognosis, the morbidity and mortality of HCC are increasing yearly. With the progress being made in modern medicine, the treatment of HCC is no longer limited to traditional methods. Targeted therapy and immunotherapy have emerged to treat advanced and metastatic HCC in recent years. Since Sorafenib is the first molecular targeting drug against angiogenesis, targeted drugs for HCC are continually emerging. Moreover, immunotherapy plays a vital role in clinical trials. In particular, the application of immune checkpoint inhibitors, which have received increasing attention in the field of cancer treatment, is a possible research path. Interestingly, these two therapies generally complement each other at some stages of HCC, bringing new hope for patients with advanced HCC. In this paper, we discuss the research progress of targeted therapy and immunotherapy for HCC in recent years, which will provide a reference for the further development of drugs for HCC.

A Structural Approach into Drug Discovery Based on Autophagy

Autophagy is a lysosome-dependent intracellular degradation machinery that plays an essential role in the regulation of cellular homeostasis. As many studies have revealed that autophagy is related to cancer, neurodegenerative diseases, metabolic diseases, and so on, and it is considered as a promising drug target. Recent advances in structural determination and computational technologies provide important structural information on essential autophagy-related proteins. Combined with high-throughput screening methods, structure-activity relationship studies have led to the discovery of molecules that modulate autophagy. In this review, we summarize the recent structural studies on autophagy-related proteins and the discovery of modulators, indicating that targeting autophagy can be utilized as an effective strategy for novel drug development.

Autophagy: A Potential Therapeutic Target of Polyphenols in Hepatocellular Carcinoma

Autophagy is a conserved biological phenomenon that maintains cellular homeostasis through the clearing of damaged cellular components under cellular stress and offers the cell building blocks for cellular survival. Aberrations in autophagy subsidize to various human pathologies, such as dementia, cardiovascular diseases, leishmaniosis, influenza, hepatic diseases, and cancer, including hepatocellular carcinoma (HCC). HCC is the fifth common mortal type of liver cancer globally, with an inhomogeneous topographical distribution and highest incidence tripled in men than women. Existing treatment procedures with liver cancer patients result in variable success rates and poor prognosis due to their drug resistance and toxicity. One of the pathophysiological mechanisms that are targeted during the development of anti-liver cancer drugs is autophagy. Generally, overactivated autophagy may lead to a non-apoptotic form of programmed cell death (PCD) or autophagic cell death or type II PCD. Emerging evidence suggests that manipulation of autophagy could induce type II PCD in cancer cells, acting as a potential tumor suppressor. Hence, altering autophagic signaling offers new hope for the development of novel drugs for the therapy of resistant cancer cells. Natural polyphenolic compounds, including flavonoids and non-flavonoids, execute their anticarcinogenic mechanism through upregulating tumor suppressors and autophagy by modulating canonical (Beclin-1-dependent) and non-canonical (Beclin-1-independent) signaling pathways. Additionally, there is evidence signifying that plant polyphenols target angiogenesis and metastasis in HCC via interference with multiple intracellular signals and decrease the risk against HCC. The current review offers a comprehensive understanding of how natural polyphenolic compounds exhibit their anti-HCC effects through regulation of autophagy, the non-apoptotic mode of cell death.

Regulation of Autophagy in Cells Infected With Oncogenic Human Viruses and Its Impact on Cancer Development

About 20% of total cancer cases are associated to infections. To date, seven human viruses have been directly linked to cancer development: high-risk human papillomaviruses (hrHPVs), Merkel cell polyomavirus (MCPyV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein–Barr virus (EBV), Kaposi’s sarcoma-associated herpesvirus (KSHV), and human T-lymphotropic virus 1 (HTLV-1). These viruses impact on several molecular mechanisms in the host cells, often resulting in chronic inflammation, uncontrolled proliferation, and cell death inhibition, and mechanisms, which favor viral life cycle but may indirectly promote tumorigenesis. Recently, the ability of oncogenic viruses to alter autophagy, a catabolic process activated during the innate immune response to infections, is emerging as a key event for the onset of human cancers. Here, we summarize the current understanding of the molecular mechanisms by which human oncogenic viruses regulate autophagy and how this negative regulation impacts on cancer development. Finally, we highlight novel autophagy-related candidates for the treatment of virus-related cancers.

Molecular targeted and immune checkpoint therapy for advanced hepatocellular carcinoma

Molecular targeted therapy for advanced hepatocellular carcinoma (HCC) has changed markedly. Although sorafenib was used in clinical practice as the first molecular targeted agent in 2007, the SHARPE and Asian-Pacific trials demonstrated that sorafenib only improved overall survival (OS) by approximately 3 months in patients with advanced HCC compared with placebo. Molecular targeted agents were developed during the 10-year period from 2007 to 2016, but every test of these agents from phase II or phase III clinical trial failed due to a low response rate and high toxicity. In the 2 years after, 2017 through 2018, four successful novel drugs emerged from clinical trials for clinical use. As recommended by updated Barcelona Clinical Liver cancer (BCLC) treatment algorithms, lenvatinib is now feasible as an alternative to sorafenib as a first-line treatment for advanced HCC. Regorafenib, cabozantinib, and ramucirumab are appropriate supplements for sorafenib as second-line treatment for patients with advanced HCC who are resistant, show progression or do not tolerate sorafenib. In addition, with promising outcomes in phase II trials, immune PD-1/PD-L1 checkpoint inhibitors nivolumab and pembrolizumab have been applied for HCC treatment. Despite phase III trials for nivolumab and pembrolizumab, the primary endpoints of improved OS were not statistically significant, immune PD-1/PD-L1 checkpoint therapy remains to be further investigated. This review summarizes the development and progression of molecular targeted and immune-based checkpoint therapies in HCC.

Harmonized Autophagy Versus Full-Fledged Hepatitis B Virus: Victorious or Defeated

Autophagy is a finely tuned process in the regulation of innate immunity to avoid excessive inflammatory responses and inflammasome signaling. In contrast, the results of recent studies have shown that autophagy may disease-dependently contribute to the pathogenesis of liver diseases, such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) during hepatitis B virus (HBV) infection. HBV has learned to subvert the cell's autophagic machinery to promote its replication. Given the great impact of the autophagy mechanism on the HBV infection and HCC, recognizing these factors may be offered new hope for human intervention and treatment of chronic HBV. This review focuses on recent findings viewing the dual role of autophagy plays in the pathogenesis of HBV infected hepatocytes.

Progress in basic and clinical research of targeted drugs for primary hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common malignancies of the digestive system. Traditional treatment is not effective for advanced hepatocellular carcinoma. Sorafenib is the first molecule-targeted drug for hepatocellular carcinoma treatment. The emergence of molecule-targeted drugs provided a new choice for patients with advanced hepatocellular carcinoma. In recent years, thanks to the development of immunotherapy, many new molecule-targeted drugs have been found to significantly improve the prognosis of patients with hepatocellular carcinoma. Therefore, targeted drugs have become a research hotspot. This article reviews the progress in basic and clinical research of molecule-targeted drugs for hepatocellular carcinoma.

Targeting the mTOR regulatory network in hepatocellular carcinoma: Are we making headway?

The mechanistic target of rapamycin (mTOR) pathway coordinates organismal growth and homeostasis in response to growth factors, nutrients, and cellular energy stage. The pathway regulates several major cellular processes and is implicated in various pathological conditions, including hepatocellular carcinoma (HCC). This review summarizes recent advances of the mTOR pathway, highlights the potential of the mTOR pathway as a therapeutic target, and explores clinical trials targeting the mTOR pathway in HCC. Although the review focuses on the mTOR pathway involved in HCC, more comprehensive discussions (eg, developing a rational design for future trials targeting the mTOR pathway) are also applicable to other tumors.

Molecular functions and clinical impact of thyroid hormone-triggered autophagy in liver-related diseases

The liver is controlled by several metabolic hormones, including thyroid hormone, and characteristically displays high lysosomal activity as well as metabolic stress-triggered autophagy, which is stringently regulated by the levels of hormones and metabolites. Hepatic autophagy provides energy through catabolism of glucose, amino acids and free fatty acids for starved cells, facilitating the generation of new macromolecules and maintenance of the quantity and quality of cellular organelles, such as mitochondria. Dysregulation of autophagy and defective mitochondrial homeostasis contribute to hepatocyte injury and liver-related diseases, such as non-alcoholic fatty liver disease (NAFLD) and liver cancer.

Thyroid hormones (TH) mediate several critical physiological processes including organ development, cell differentiation, metabolism and cell growth and maintenance. Accumulating evidence has revealed dysregulation of cellular TH activity as the underlying cause of several liver-related diseases, including alcoholic or non-alcoholic fatty liver disease and liver cancer. Data from epidemiologic, animal and clinical studies collectively support preventive functions of THs in liver-related diseases, highlighting the therapeutic potential of TH analogs. Elucidation of the molecular mechanisms and downstream targets of TH should thus facilitate the development of therapeutic strategies for a number of major public health issues.

Here, we have reviewed recent studies focusing on the involvement of THs in hepatic homeostasis through induction of autophagy and their implications in liver-related diseases. Additionally, the potential underlying molecular pathways and therapeutic applications of THs in NAFLD and HCC are discussed.

Autophagy: Dual Response in the Development of Hepatocellular Carcinoma

Autophagy is an evolutionary conserved intracellular mechanism which helps eukaryotic cells in maintaining their metabolic state to afford high-efficiency energy requirements. In the physiology of a normal liver and the pathogenesis of liver diseases, autophagy plays a crucial role. Autophagy has been found to be both upregulated and downregulated in different cancers providing the evidence that autophagy plays a dual role in suppressing and promoting cell survival. Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the major leading cause of cancer mortality worldwide. In light of its high complexity and poor prognosis, it is essential to improve our understanding of autophagy’s role in HCC. In this review, we summarize the dual mechanism of autophagy in the development of HCC and elucidate the currently used therapeutic strategies for anti-HCC therapy.

Recent advances in molecular targeted therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second most common cause of mortality from any type of cancer, and its mortality has risen in recent years in China. Because of its insidious onset, rapid progression, and poor prognosis, HCC has become a hot and difficult research topic. HCC therapy, especially the use and research of molecular targeted drugs, has achived significant advances and opened up a new avenue for the treatment of HCC. In this paper, we will describe the recent advances in the research of of signaling pathways and potential molecular targets, the clinical use of molecular targeted drugs, and new molecular targeted drugs for HCC.

Multidisciplinary approach for post-liver transplant recurrence of hepatocellular carcinoma: A proposed management algorithm

A large number of liver transplants have been performed for hepatocellular carcinoma (HCC), and recurrence is increasingly encountered. The recurrence of HCC after liver transplantation is notoriously difficult to manage. We hereby propose multi-disciplinary management with a systematic approach. The patient is jointly managed by the transplant surgeon, physician, oncologist and radiologist. Immunosuppressants should be tapered to the lowest effective dose to protect against rejection. The combination of a mammalian target of rapamycin inhibitor with a reduced calcineurin inhibitor could be considered with close monitoring of graft function and toxicity. Comprehensive staging can be performed by dual-tracer positron emission tomography-computed tomography or the combination of contrast computed tomography and a bone scan. In patients with disseminated recurrence, sorafenib confers survival benefits but is associated with significant drug toxicity. Oligo-recurrence encompasses recurrent disease that is limited in number and location so that loco-regional treatments convey disease control and survival benefits. Intra-hepatic recurrence can be managed with graft resection, but significant operative morbidity is expected. Radiofrequency ablation and stereotactic body radiation therapy (SBRT) are effective alternative strategies. In patients with more advanced hepatic disease, regional treatment with trans-arterial chemoembolization or intra-arterial Yttrium-90 can be considered. For patients with extra-hepatic oligo-recurrence, loco-regional treatment can be considered if practical. Patients with more than one site of recurrence are not always contraindicated for curative treatments. Surgical resection is effective for patients with pulmonary oligo-recurrence, but adequate lung function is a pre-requisite. SBRT is a non-invasive and effective modality that conveys local control to pulmonary and skeletal oligo-recurrences.

Role of autophagy in tumorigenesis, metastasis, targeted therapy and drug resistance of hepatocellular carcinoma

Autophagy is a “self-degradative” process and is involved in the maintenance of cellular homeostasis and the control of cellular components by facilitating the clearance or turnover of long-lived or misfolded proteins, protein aggregates, and damaged organelles. Autophagy plays a dual role in cancer, including in tumor progression and tumor promotion, suggesting that autophagy acts as a double-edged sword in cancer cells. Liver cancer is one of the greatest leading causes of cancer death worldwide due to its high recurrence rate and poor prognosis. Especially in China, liver cancer has become one of the most common cancers due to the high infection rate of hepatitis virus. In primary liver cancer, hepatocellular carcinoma (HCC) is the most common type. Considering the perniciousness and complexity of HCC, it is essential to elucidate the function of autophagy in HCC. In this review, we summarize the physiological function of autophagy in cancer, analyze the role of autophagy in tumorigenesis and metastasis, discuss the therapeutic strategies targeting autophagy and the mechanisms of drug-resistance in HCC, and provide potential methods to circumvent resistance and combined anticancer strategies for HCC patients.

Sirolimus in Liver Transplant Recipients with Hepatocellular Carcinoma: An Updated Meta-Analysis

Previous studies have indicated that sirolimus (SRL) may be effective for HCC patients undergoing liver transplantation (LT). However, the following results are still contradictory and do not have a clear conclusion. Therefore, we conducted an updated meta-analysis by retrieving published data in EMBASE, PubMed, and the Cochrane Library up to October 2017. Both efficiency and safety of SRL were analyzed using pooled odds ratio (ORs) with 95% confidence interval (CIs). A total of 11 studies involving 7,695 HCC patients were included. Compared with control group, SRL prolonged 1-year (OR = 2.44; CI = 1.66-3.59), 3 year (OR = 1.67; CI = 1.08-2.58) and 5-year (OR = 1.68; CI = 1.21-2.33) overall survival, as well as 1-year (OR = 2.13; CI = 1.19-3.81) disease-free survival. Pooled results found that SRL-treated patients had lower recurrence (OR = 0.60; CI = 0.37-0.98), lower recurrence-related mortality (OR = 0.58; CI = 0.42-0.81) and lower overall mortality (OR = 0.62; CI = 0.44-0.89). Moreover, fewer SRL-treated patients suffered from portal vein thrombosis (OR = 0.29; CI, 0.09-0.91) and diabetes (OR = 0.23; CI = 0.12-0.47), while SRL-treated patients were more vulnerable to acne compared with the control group (OR = 4.44; CI = 1.56-12.60). No significant differences in other adverse effects were found between two groups. Taken together, SRL-based immunosuppression is safe and effective in improving survival, as well as reducing recurrence and mortality for HCC patients following LT.

Nrf2-p62 autophagy pathway and its response to oxidative stress in hepatocellular carcinoma

Deregulation of autophagy is proposed to play a key pathogenic role in hepatocellular carcinoma (HCC), the most common primary malignancy of the liver and the third leading cause of cancer death. Autophagy is an evolutionarily conserved catabolic process activated to degrade and recycle cell's components. Under stress conditions, such as oxidative stress and nutrient deprivation, autophagy is an essential survival pathway that operates in harmony with other stress response pathways. These include the redox-sensitive transcription complex Nrf2-Keap1 that controls groups of genes with roles in detoxification and antioxidant processes, intermediary metabolism, and cell cycle regulation. Recently, a functional association between a dysfunctional autophagy and Nrf2 pathway activation has been identified in HCC. This appears to occur through the physical interaction of the autophagy adaptor p62 with the Nrf2 inhibitor Keap1, thus leading to increased stabilization and transcriptional activity of Nrf2, a key event in reprogramming metabolic and stress response pathways of proliferating hepatocarcinoma cells. These emerging molecular mechanisms and the therapeutic perspective of targeting Nrf2-p62 interaction in HCC are discussed in this paper along with the prognostic value of autophagy in this type of cancer.

Effect of sirolimus on liver cirrhosis and hepatic encephalopathy of common bile duct-ligated rats

Cirrhosis is often associated with portal hypertension and portal-systemic collateral vessels formation attributed to angiogenesis, which leads to severe complications as hepatic encephalopathy. Sirolimus has anti-fibrosis and anti-angiogenesis effects, but whether it influences the severity of portal-systemic collaterals and hepatic encephalopathy is unknown. This study was thus designed to address this issue in rats with common bile duct ligation-induced liver cirrhosis. Sham-operated rats were surgical controls. Rats were intraperitoneally administered with 0.5 and 2 mg/kg/day sirolimus or vehicle for 2 weeks. Four weeks post operations, motor activities, body weight, biochemistry and hemodynamic data were measured. The liver was dissected for histopathology, immunohistochemical stains and protein analysis. On the parallel cirrhotic groups, the portal-systemic shunting was determined. The results showed that the body weight gain was significantly lower in sirolimus-treated rats. Sirolimus reduced portal pressure and plasma levels of alanine aminotransferase, aspartate aminotransferase and ammonia, and attenuated hepatic inflammation and fibrosis in cirrhotic rats. In addition, the hepatic phosphorylated mammalian target of rapamycin (mTOR) and P70S6K protein expressions were significantly downregulated and endothelial nitric oxide synthase (eNOS) expression upregulated by sirolimus. Sirolimus did not influence portal-systemic shunting and motor activities of cirrhotic rats. In conclusion, sirolimus significantly improved hepatic inflammation and fibrosis accompanied by portal pressure reduction in cirrhotic rats, in which down-regulated mTOR/P70S6K and up-regulated eNOS expressions might play a role. However, sirolimus did not significantly change the severity of portal-systemic collaterals and motor activities, suggesting that the multifactorial pathogenesis of hepatic encephalopathy could not be fully overcome by sirolimus.

Autophagy Modulation in Cancer: Current Knowledge on Action and Therapy

In the last two decades, accumulating evidence pointed to the importance of autophagy in various human diseases. As an essential evolutionary catabolic process of cytoplasmatic component digestion, it is generally believed that modulating autophagic activity, through targeting specific regulatory actors in the core autophagy machinery, may impact disease processes. Both autophagy upregulation and downregulation have been found in cancers, suggesting its dual oncogenic and tumor suppressor properties during malignant transformation. Identification of the key autophagy targets is essential for the development of new therapeutic agents. Despite this great potential, no therapies are currently available that specifically focus on autophagy modulation. Although drugs like rapamycin, chloroquine, hydroxychloroquine, and others act as autophagy modulators, they were not originally developed for this purpose. Thus, autophagy may represent a new and promising pharmacologic target for future drug development and therapeutic applications in human diseases. Here, we summarize our current knowledge in regard to the interplay between autophagy and malignancy in the most significant tumor types: pancreatic, breast, hepatocellular, colorectal, and lung cancer, which have been studied in respect to autophagy manipulation as a promising therapeutic strategy. Finally, we present an overview of the most recent advances in therapeutic strategies involving autophagy modulators in cancer.

Autophagy suppresses proliferation of HepG2 cells via inhibiting glypican-3/wnt/β-catenin signaling

Introduction

Autophagy plays an important role in the growth and survival of hepatocellular carcinoma (HCC) cells through several target proteins or signaling pathways. Glypican-3 (GPC3) is a new reliable HCC marker, which is involved in tumor growth in HCC, primarily mediated by wnt/β-catenin signaling.

Objective

The present study aimed to identify the role of autophagy in the proliferation of HepG2 cells through GPC3/wnt/β-catenin signaling.

Results and discussion

Results demonstrated that induction of autophagy by nutrition starvation and rapamycin treatment led to the downregulation of GPC3 expression in HepG2 cells, accompanied by the decreased expression of wnt downstream target genes (β-catenin, c-myc and cyclin D1). On the other hand, inhibition of autophagy by 3-methyl adenine (3-MA) could rescue rapamycin-directed downregulation of GPC3 and wnt/β-catenin target genes and augment the proliferation of HepG2 cells. Furthermore, interference of GPC3 by siRNA suppressed wnt/β-catenin signaling and attenuated 3-MA stimulation of HepG2 cell proliferation. More interestingly, the mRNA of GPC3 remained unchanged when the protein levels of GPC3 were decreased by autophagy activation, suggesting that induction of autophagy may accelerate the degradation of GPC3.

Conclusion

These results suggest that autophagy suppresses proliferation of HepG2 cells partially by inhibition of GPC3/wnt/β-catenin signaling.

Targeting multiple oncogenic pathways for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common forms of liver cancer diagnosed worldwide. HCC occurs due to chronic liver disease and is often diagnosed at advanced stages. Chemotherapeutic agents such as doxorubicin are currently used as first-line agents for HCC therapy, but these are non-selective cytotoxic molecules with significant side effects. Sorafenib, a multi-targeted tyrosine kinase inhibitor, is the only approved targeted drug for HCC patients. However, due to adverse side effects and limited efficacy, there is a need for the identification of novel pharmacological drugs beyond sorafenib. Several agents that target and inhibit various signaling pathways involved in HCC are currently being assessed for HCC treatment. In the present review article, we summarize the diverse signal transduction pathways responsible for initiation as well as progression of HCC and also the potential anticancer effects of selected targeted therapies that can be employed for HCC therapy.

Inhibiting 4EBP1 in Glioblastoma

Glioblastoma is the most common and aggressive adult brain cancer. Tumors show frequent dysregulation of the PI3K-mTOR pathway. Although a number of small molecules target the PI3K-AKT-mTOR axis, their preclinical and clinical efficacy has been limited. Reasons for treatment failure include poor penetration of agents into the brain and observations that blockade of PI3K or AKT minimally affects downstream mTOR activity in glioma. Clinical trials using allosteric mTOR inhibitors (rapamycin and rapalogs) to treat patients with glioblastoma have also been unsuccessful or uncertain, in part, because rapamycin inefficiently blocks the mTORC1 target 4EBP1 and feeds back to activate PI3K-AKT signaling. Inhibitors of the mTOR kinase (TORKi) such as TAK-228/MLN0128 interact orthosterically with the ATP- and substrate-binding pocket of mTOR kinase, efficiently block 4EBP1 in vitro, and are currently being investigated in the clinical trials. Preclinical studies suggest that TORKi have poor residence times of mTOR kinase, and our data suggest that this poor pharmacology translates into disappointing efficacy in glioblastoma xenografts. RapaLink-1, a TORKi linked to rapamycin, represents a drug with improved pharmacology against 4EBP1. In this review, we clarify the importance of 4EBP1 as a biomarker for the efficacy of PI3K-AKT-mTOR inhibitors in glioblastoma. We also review mechanistic data by which RapaLink-1 blocks p-4EBP1 and discuss future clinical strategies for 4EBP1 inhibition in glioblastoma. Clin Cancer Res; 24(1); 14-21. ©2017 AACR.

Combination of Photon and Carbon Ion Irradiation with Targeted Therapy Substances Temsirolimus and Gemcitabine in Hepatocellular Carcinoma Cell Lines

Background

This work investigates on putative cytotoxic effects in four different hepatocellular carcinoma (HCC) cell lines after irradiation with photons or carbon ions in combination with new targeted molecular therapy using either Temsirolimus (TEM) or Gemcitabine (GEM).

Methods and materials

The HCC cell lines HepG2, Hep3B, HuH7, and PLC were cultured and irradiated with photons or carbon ions at the Heidelberg Ion Beam Therapy Center using the raster-scanning method. For combination experiments, cell lines were first treated with Temsirolimus or GEM before irradiation. Cytotoxicity was measured by a clonogenic survival assay. The evaluation of the experiments and the obtained survival curves were based on the concept of additivity defined by Steel and Peckham.

Results

The results for the combination of carbon ions and both tested systemic substances TEM and GEM showed independent toxicities in all four cell lines. Supra-additive effects were observed in PLC cells for photon irradiation combined either with TEM or GEM and in HuH7 cells for the combination of photons with TEM.

Conclusion

Addition of targeted therapy substances Temsirolimus and GEM to photon irradiation showed additive cytotoxicity in HCC cell lines, whereas independent toxicities where reached by the combination of carbon ions to these substances. It can be assumed that combining 12C with systemic substances only has independent effects because heavy ions cause direct damage because of their high-LET character resulting in complex and clustered double-strand breaks. Nonetheless, further investigations are warranted in order to determine whether addition of systemic therapy allows a reduction of radiation doses in combination therapy. This could possibly lead to better responses and tolerances in patients with HCC.

Rapamycin regulates the proliferation of Huh7, a hepatocellular carcinoma cell line, by up-regulating p53 expression

Rapamycin, a specific inhibitor of mTOR used extensively as an immunosuppressant, has been expanded recently to cancer therapy, because the mTOR signal is known to be up-regulated in various cancer cells including hepatocellular carcinoma (HCC) cells. In spite of extensive efforts to employ mTOR inhibitors as anti-HCC therapy, they have not yet been approved by the FDA. Because of the heterogeneity and complexity of molecular signaling in HCC, suitable biomarkers should be identified or discovered to improve clinical efficacy of mTOR-specific inhibitors to HCC cells. In this study, the effect of rapamycin was investigated on two different HCC cell lines, Huh7 cells and HepG2 cells. Rapamycin was found to inhibit the proliferation of Huh7 cells but not of HepG2 cells. Moreover, it was found that rapamycin can up-regulate p53 at the protein level, but not affect its transcript. To understand the critical role of p53 in the rapamycin effect, knock-down experiments were performed using small-interfering RNAs (siRNAs). The anti-proliferative effect of rapamycin on Huh7 cells clearly disappeared after blocking p53 production with siRNA, which indicates that p53 is a critical factor in the anti-proliferative effect of rapamycin in HCC cells. The over-expression system of p53 was also employed to mimic the effect of rapamycin and found that cell proliferation was clearly down-regulated by p53 over-expression. Finally, we found that the extracellular signal-regulated kinase 1/2 (ERK1/2) signal was regulated by p53 whose expression was induced by rapamycin. Overall, this study demonstrates that rapamycin inhibited the proliferation of Huh7 cells by up-regulating the expression of p53 and down-regulating the ERK1/2 signal, indicating that p53 is a useful biomarker for anti-cancer therapy using the specific inhibitor of mTOR signal, rapamycin, against hepatocellular carcinoma cells.

Hepatocellular carcinoma: A comprehensive review

Hepatocellular carcinoma (HCC) is rapidly becoming one of the most prevalent cancers worldwide. With a rising rate, it is a prominent source of mortality. Patients with advanced fibrosis, predominantly cirrhosis and hepatitis B are predisposed to developing HCC. Individuals with chronic hepatitis B and C infections are most commonly afflicted. Different therapeutic options, including liver resection, transplantation, systemic and local therapy, must be tailored to each patient. Liver transplantation offers leading results to achieve a cure. The Milan criteria is acknowledged as the model to classify the individuals that meet requirements to undergo transplantation. Mean survival remains suboptimal because of long waiting times and limited donor organ resources. Recent debates involve expansion of these criteria to create options for patients with HCC to increase overall survival.

The Role of Autophagy in Hepatocellular Carcinoma

Autophagy is a catabolic process involved in cellular homeostasis under basal and stressed conditions. Autophagy is crucial for normal liver physiology and the pathogenesis of liver diseases. During the last decade, the function of autophagy in hepatocellular carcinoma (HCC) has been evaluated extensively. Currently, autophagy is thought to play a dual role in HCC, i.e., autophagy is involved in tumorigenesis and tumor suppression. Recent investigations of autophagy have suggested that autophagy biomarkers can facilitate HCC prognosis and the establishment of therapeutic approaches. In this review, we briefly summarize the current understanding of autophagy and discuss recent evidence for its role in HCC.

mTORC1 Up-Regulates GP73 to Promote Proliferation and Migration of Hepatocellular Carcinoma Cells and Growth of Xenograft Tumors in Mice

BACKGROUND & AIMS

Levels of the Golgi protein 73 (GP73) increase during development of hepatocellular carcinoma (HCC); GP73 is a serum marker for HCC. However, little is known about the mechanisms or effects of GP73 during hepatic carcinogenesis.

METHODS

GP73 was overexpressed from a retroviral vector in HepG2 cells, which were analyzed in proliferation and migration assays. Xenograft tumors were grown from these cells in nude mice. The effects of monoclonal antibodies against GP73 were studied in mice and cell lines. GP73(-/-), GP73(+/-), and GP73(+/+) mice were given injections of diethylnitrosamine to induce liver injury. Levels of GP73 were reduced in MHCC97H, HCCLM3, and HepG2.215 cell lines using small hairpin RNAs; xenograft tumors were grown in mice from MHCC97H-small hairpin GP73 or MHCC97H-vector cells. We used microarray analysis to compare expression patterns between GP73-knockdown and control MHCC97H cells. We studied the effects of the mechanistic target of rapamycin (mTOR) inhibitor rapamycin on GP73 expression in different cancer cell lines and on growth of tumors in mice. Levels of GP73 and activated mTOR were quantified in human HCC tissues.

RESULTS

Xenograft tumors grown from HepG2 cells that expressed GP73 formed more rapidly and more metastases than control HepG2 cells in mice. A monoclonal antibody against GP73 reduced proliferation of HepG2 cells and growth of xenograft tumors in mice. GP73(-/-) mice had less liver damage after administration of diethylnitrosamine than GP73(+/-) or GP73(+/+) mice. In phosphatase and tensin homolog-null mouse embryonic fibroblasts with constitutively activated mTOR, GP73 was up-regulated compared with control mouse embryonic fibroblasts; this increase was reversed after incubation with rapamycin. Expression of GP73 also was reduced in HCC and other cancer cell lines incubated with rapamycin. mTORC1 appeared to regulate expression of GP73 in cell lines. Activated mTOR correlated with the level of GP73 in human HCC tissues. Injection of rapamycin slowed the growth of xenograft tumors from MHCC97H-vector cells, compared with MHCC97H-short hairpin GP73 cells.

CONCLUSIONS

Increased expression of GP73 promotes proliferation and migration of HCC cell lines and growth of xenograft tumors in mice. mTORC1 regulates the expression of GP73, so GP73 up-regulation can be blocked with rapamycin. mTOR inhibitors or other reagents that reduce the level or activity of GP73 might be developed for the treatment of HCC.

Clinical efficacy of mTOR inhibitors in solid tumors: a systematic review

ABSTRACT 

The common dysregulation of the mTOR signaling pathway in tumor cells makes it a key target in oncotherapy. To better understand the effects of mTOR inhibitors, we analyzed 32 published clinical trials on solid tumors other than renal cell cancer, neuroendocrine tumors and metastatic breast cancer, for mTOR inhibitors are already approved by the US FDA to treat the three cancers. A lack of therapeutic effects was observed when mTOR inhibitors were used as a single agent. When combined with other agents, mTOR inhibitors still lacked sufficient clinical activity or just had minimal activity. More studies are required to better understand the clinically effects of mTOR inhibitors and the development of novel mTOR inhibitors is absolutely necessary.

Molecular targeted therapy in hepatocellular carcinoma: from biology to clinical practice and future

OPINION STATEMENT

Hepatocellular carcinoma (HCC) is one of the most lethal cancers globally, particularly in certain regions of the world. Although the major risk factors for HCC have been identified, the specific mechanisms driving hepatocarcinogenesis remain unclear. Sorafenib is the only systemic therapy that has demonstrated an overall survival benefit in patients with advanced HCC and does so primarily through antiangiogenic activity. However, that actual benefit is still relatively small. Extensive research has focused on targeting dysfunctional molecular pathways in HCC. Despite promising preclinical and early-phase studies, other agents have failed to expand upon the efficacy of sorafenib in large-scale randomized trials. As the development of treatment options in the post-sorafenib setting is ongoing, more efforts are being focused on (1) evaluation of molecular agents targeting pathogenic, HCC-specific pathways; (2) the combination of targeted and cytotoxic therapies in selected subgroups; and (3) the combination of systemic and locoregional therapies in various settings. This article provides a review of recently completed and ongoing studies of molecular targeted agents in HCC, including a brief description of the biologic rationale behind these agents.

mTOR inhibitor therapy: Does it prevent HCC recurrence after liver transplantation?

Prevention of hepatocellular carcinoma (HCC) recurrence after liver transplantation is a clinical priority. The importance of the mammalian target of rapamycin (mTOR) pathway in cell growth and survival makes it a logical target for antitumor strategies, as borne out by clinical data in various types of malignancy. A number of studies have indicated that the mTOR inhibitors everolimus and sirolimus suppress cell proliferation and tumor growth in animal models of HCC. Coadministration of an mTOR inhibitor could permit lower dosing of chemotherapeutic agents in HCC management, and trials in non-transplant HCC population are exploring combined used with various agents including sorafenib, the vascular endothelial growth factor inhibitor bevacizumab and conventional agents. In terms of a preventive effect after liver transplantation for HCC, data from retrospective studies and non-randomized prospective analyses in which patients received an mTOR inhibitor with concomitant calcineurin inhibitor therapy have indicated that HCC recurrence rates and overall survival may be improved compared to a standard calcineurin inhibitor regimen. Meta-analyses have supported these findings, but controlled trials are required before any firm conclusions can be drawn. In two of the three randomized trials which have assessed de novo mTOR inhibitor therapy after liver transplantation, there was a numerically lower rate of HCC recurrence by one year post-transplant in patients given an mTOR inhibitor versus the control arm, but absolute numbers were low. Overall, based on the available data from retrospective studies, meta-analyses, and post-hoc assessments of randomized trials, it appears advisable to consider mTOR inhibition-based immunosuppression after transplantation for HCC, particularly in patients who exceed the Milan criteria. Prospective data are awaited.

Rapamycin inhibits Toll-like receptor 4-induced pro-oncogenic function in head and neck squamous cell carcinoma

Toll-like receptor 4 (TLR4) is expressed in head and neck squamous cell carcinoma (HNSCC) cells and is associated with HNSCC cancer progression. Rapamycin has been proven to be efficient for the treatment of HNSCC in vivo, yet the mechanism is not understood and rapamycin demonstrates little effect in vitro. In the present study, the HNSCC cell lines CAL27 and SCC4 were pre-treated with rapamycin then stimulated with a TLR4 ligand lipopolysaccharide (LPS). Cell proliferation, migration, invasion, resistance to TRAIL-induced apoptosis, cytokine production, NF-κB and p65 activation were determined. The results indicated that LPS significantly stimulated HNSCC cell proliferation, cytokine production, migration, invasion and resistance to apoptosis induced by tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL). Pretreatment with rapamycin significantly attenuated LPS-induced pro-oncogenic effects by inhibiting the activation of NF-κB by LPS. siRNA knockdown of TLR4 in HNSCC cells demonstrated that rapamycin attenuated LPS-induced pro-oncogenic effects via TLR4. Hence, this study suggests rapamycin may be efficient for the treatment of HNSCC by attenuating TLR4-induced pro-oncogenic effects.

Targeting the mTOR pathway in hepatocellular carcinoma: current state and future trends

Mechanistic target of rapamycin (mTOR) regulates cell growth, metabolism and aging in response to nutrients, cellular energy stage and growth factors. mTOR is frequently up-regulated in cancer including hepatocellular carcinoma (HCC) and is associated with bad prognosis, poorly differentiated tumors, and earlier recurrence. Blocking mTOR with rapamycin and first generation mTOR inhibitors, called rapalogs, has shown promising reduction of HCC tumor growth in preclinical models. Currently, rapamycin/rapalogs are used in several clinical trials for the treatment of advanced HCC, and as adjuvant therapy in HCC patients after liver transplantation and TACE. A second generation of mTOR pathway inhibitors has been developed recently and is being tested in various clinical trials of solid cancers, and has been used in preclinical HCC models. The results of series of clinical trials using mTOR inhibitors in HCC treatment will emerge in the near future.

Rationale of personalized immunosuppressive medication for hepatocellular carcinoma patients after liver transplantation

Liver transplantation is the only potentially curative treatment for hepatocellular carcinoma (HCC) that is not eligible for surgical resection. However, disease recurrence is the main challenge to the success of this treatment. Immunosuppressants that are universally used after transplantation to prevent graft rejection could potentially have a significant impact on HCC recurrence. Nevertheless, current research is exclusively focused on mammalian target of rapamycin inhibitors, which are thought to be the only class of immunosuppressive agents that can reduce HCC recurrence. In fact, substantial evidence from the bench to the bedside indicates that other classes of immunosuppressants may also exert diverse effects; for example, inosine monophosphate dehydrogenase inhibitors potentially have antitumor effects. In this article, we aim to provide a comprehensive overview of the potential effects of different types of immunosuppressants on HCC recurrence and their mechanisms of action from both experimental and clinical perspectives. To ultimately improve the outcomes of HCC patients after transplantation, we propose a concept and approaches for developing personalized immunosuppressive medication to be used either as immunosuppression maintenance or during the prevention/treatment of HCC recurrence.

Liver autophagy: much more than just taking out the trash

Studies performed in the liver in the 1960s led to the identification of lysosomes and the discovery of autophagy, the process by which intracellular proteins and organelles are degraded in lysosomes. Early studies in hepatocytes also uncovered how nutritional status regulates autophagy and how various circulating hormones modulate the activity of this catabolic process in the liver. The intensive characterization of hepatic autophagy over the years has revealed that lysosome-mediated degradation is important not only for maintaining liver homeostasis in normal physiological conditions, but also for an adequate response of this organ to stressors such as proteotoxicity, metabolic dysregulation, infection and carcinogenesis. Autophagic malfunction has also been implicated in the pathogenesis of common liver diseases, suggesting that chemical manipulation of this process might hold potential therapeutic value. In this Review--intended as an introduction to the topic of hepatic autophagy for clinical scientists--we describe the different types of hepatic autophagy, their role in maintaining homeostasis in a healthy liver and the contribution of autophagic malfunction to liver disease.

Quality of life associated with sirolimus for prevention of graft-versus-host disease: results from a randomized trial

Several studies have examined sirolimus-based immune suppression for the prevention of graft-versus-host disease after allogeneic hematopoietic cell transplantation, but little is known regarding its effects on quality of life. The current study reports on changes in quality of life to Day 360 in a randomized phase II trial of sirolimus and tacrolimus versus methotrexate and tacrolimus. Quality of life was assessed prior to transplant and on Days 30, 90, 180, 270, and 360 with the Functional Assessment of Cancer Therapy - Bone Marrow Transplant Trial Outcome Index. Random effects models examined the effects of study arm on change in Trial Outcome Index scores from Day 30 to 360, controlling for base-line Trial Outcome Index. The sirolimus/tacrolimus arm (n=37) showed less improvement in Trial Outcome Index scores over time compared to the methotrexate/tacrolimus arm (n=34) (P=0.02). Patients receiving sirolimus and tacrolimus were more likely to endorse nausea and a lack of energy over time (PS≤0.01). These data suggest that sirolimus-based immune suppression is associated with less improvement in quality of life in the first year post-transplant compared to methotrexate/tacrolimus. Quality of life differences may be due to increased fatigue and nausea in patients treated with sirolimus. These findings should be considered in the clinical management of patients treated with sirolimus. (Clinicaltrials.gov identifier:00803010).

Molecular targeted therapy for hepatocellular carcinoma: current and future

Hepatocellular carcinoma (HCC) is one of the most frequent tumors worldwide. The majority of HCC cases occur in patients with chronic liver disease. Despite regular surveillance to detect small HCC in these patients, HCC is often diagnosed at an advanced stage. Because HCC is highly resistant to conventional systemic therapies, the prognosis for advanced HCC patients remains poor. The introduction of sorafenib as the standard systemic therapy has unveiled a new direction for future research regarding HCC treatment. However, given the limited efficacy of the drug, a need exists to look beyond sorafenib. Many molecular targeted agents that inhibit different pathways involved in hepatocarcinogenesis are under various phases of clinical development, and novel targets are being assessed in HCC. This review aims to summarize the efforts to target molecular components of the signaling pathways that are responsible for the development and progression of HCC and to discuss perspectives on the future direction of research.

The mTOR pathway in hepatic malignancies

The mechanistic/mammalian target of rapamycin (mTOR) pathway plays a critical role in cellular metabolism, growth, and proliferation and has been evaluated as a target for therapy in various malignancies. The mTOR pathway is a major tumor-initiating pathway in hepatocellular carcinoma, with up-regulation seen in up to 50% of tumors. Metformin, which represses mTOR signaling by activating adenosine monophosphate-activated protein kinase, has been shown to decrease liver carcinogenesis in population studies. mTOR inhibitors such as everolimus have been evaluated as adjunctive chemotherapy with some success, although efficacy has been limited by the lack of complete mTOR pathway inhibition. The active site mTOR inhibitors hold greater promise, given that they offer complete mTOR suppression. There is also evidence of mTOR pathway activation in cholangiocarcinoma, although its biological significance in initiating and promoting tumor progression remains ambiguous. This review provides an overview of the complex biochemistry behind the mTOR pathway and its role in carcinogenesis, especially as it pertains to hepatic malignancies.

Clinical trials in hepatocellular carcinoma: an update

The success of sorafenib has spurred an explosive increase of clinical trials testing novel molecular targets and other agents in the treatment of hepatocellular carcinoma (HCC). The paradigm of the studies has been characterized by three noticeable changes. First, the molecular targets of interest have expanded from angiogenesis to cancer cell-directed oncogenic signaling pathways for advanced HCC treatment. Agents targeting EGFR, FGFR, PI3K/Akt/mTOR, TGF-β, c-Met, MEK, IGF signaling, and histone deacetylase have been actively explored. Second, the target indication has shifted from advanced stage to early or intermediate stages of disease. The feasibility of combining locoregional therapies and targeted agents, and the use of novel agents after curative treatments are currently under active investigation. Finally, the therapeutic strategy has shifted from monotherapy to combination targeted therapy. We aim to provide a comprehensive overview of newly disclosed and ongoing clinical trials for the treatment of HCC.

Temsirolimus combined with sorafenib in hepatocellular carcinoma: a phase I dose-finding trial with pharmacokinetic and biomarker correlates

BACKGROUND

Based upon preclinical evidence for improved antitumor activity in combination, this phase I study investigated the maximum-tolerated dose (MTD), safety, activity, pharmacokinetics (PK), and biomarkers of the mammalian target of rapamycin inhibitor, temsirolimus, combined with sorafenib in hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Patients with incurable HCC and Child Pugh score ≤B7 were treated with sorafenib plus temsirolimus by 3 + 3 design. The dose-limiting toxicity (DLT) interval was 28 days. The response was assessed every two cycles. PK of temsirolimus was measured in a cohort at MTD.

RESULTS

Twenty-five patients were enrolled. The MTD was temsirolimus 10 mg weekly plus sorafenib 200 mg twice daily. Among 18 patients at MTD, DLT included grade 3 hand-foot skin reaction (HFSR) and grade 3 thrombocytopenia. Grade 3 or 4 related adverse events at MTD included hypophosphatemia (33%), infection (22%), thrombocytopenia (17%), HFSR (11%), and fatigue (11%). With sorafenib, temsirolimus clearance was more rapid (P < 0.05). Two patients (8%) had a confirmed partial response (PR); 15 (60%) had stable disease (SD). Alpha-fetoprotein (AFP) declined ≥50% in 60% assessable patients.

CONCLUSION

The MTD of sorafenib plus temsirolimus in HCC was lower than in other tumor types. HCC-specific phase I studies are necessary. The observed efficacy warrants further study.

Islet transplantation in type 1 diabetes: ongoing challenges, refined procedures, and long-term outcome

Remarkable progress has been made in islet transplantation over a span of 40 years. Once just an experimental curiosity in mice, this therapy has moved forward, and can now provide robust therapy for highly selected patients with type 1 diabetes (T1D), refractory to stabilization by other means. This progress could not have occurred without extensive dynamic international collaboration. Currently, 1,085 patients have undergone islet transplantation at 40 international sites since the Edmonton Protocol was reported in 2000 (752 allografts, 333 autografts), according to the Collaborative Islet Transplant Registry. The long-term results of islet transplantation in selected centers now match registry data of pancreas-alone transplantation, with 6 sites reporting five-year insulin independence rates ≥50%. Islet transplantation has been criticized for the use of multiple donor pancreas organs, but progress has also occurred in single-donor success, with 10 sites reporting increased single-donor engraftment. The next wave of innovative clinical trial interventions will address instant blood-mediated inflammatory reaction (IBMIR), apoptosis, and inflammation, and will translate into further marked improvements in single-donor success. Effective control of auto- and alloimmunity is the key to long-term islet function, and high-resolution cellular and antibody-based assays will add considerable precision to this process. Advances in immunosuppression, with new antibody-based targeting of costimulatory blockade and other T-B cellular signaling, will have further profound impact on the safety record of immunotherapy. Clinical trials will move forward shortly to test out new human stem cell derived islets, and in parallel trials will move forward, testing pig islets for compatibility in patients. Induction of immunological tolerance to self-islet antigens and to allografts is a difficult challenge, but potentially within our grasp.

A Phase 1 dose-finding and pharmacodynamic study of rapamycin in combination with bevacizumab in patients with unresectable hepatocellular carcinoma

BACKGROUND & AIMS

Preclinical studies have demonstrated the additive effect of rapamycin with bevacizumab for hepatocellular carcinoma treatment. We conducted a Phase 1 study to evaluate the safety and pharmacokinetics of the combination in patients with hepatocellular carcinoma.

METHODS

Adult participants with advanced hepatocellular carcinoma received intravenous bevacizumab (5mg/kg every 14 days) and oral rapamycin (1-6 mg/day; 3+3 dose escalation design). Computed tomography assessed tumour response and treatment safety. Pharmacokinetics assessment established rapamycin blood concentrations pre- and post-dose. Dynamic contrast-enhanced computed tomography analysed the tumour region for blood flow, permeability surface area product, fractional intravascular blood volume and extracellular-extravascular volume.

RESULTS

Twenty-four participants were treated. There were two dose limiting toxicities with rapamycin 5mg: grade 3 thrombocytopenia and grade 3 mucositis. The maximally tolerated dose of rapamycin was 4 mg. Adverse events (grade 1-2) included hyperglycaemia (83%), thrombocytopenia (75%), fatigue (46%), mucositis (46%), anorexia (42%), diarrhoea (33%) and proteinuria (12.5%). Of 20 evaluable participants, one reached complete response that lasted 4.5 months, two reached partial response, 14 reached stable disease and three had progressive disease. Median overall survival was 9.4 months; progression-free survival was 5.5 months. Dose level and steady state area under the concentration time curve for hour zero to infinity of rapamycin correlated inversely with blood flow rate and change in permeability-surface area. After 22 days of treatment, there were significant reductions from baseline in blood flow rate, permeability-surface area and fractional intracellular blood volume.

CONCLUSIONS

The recommended Phase 2 dose of rapamycin is 4 mg in combination with bevacizumab. Evidence of anti-vascular activity was observed together with promising clinical activity.

Current and Future Treatment Strategies for Patients with Advanced Hepatocellular Carcinoma: Role of mTOR Inhibition

Hepatocellular carcinoma (HCC) is a common cancer that has the third highest cancer-related mortality rate worldwide. Although potentially curable by transplantation if detected early, the majority of cases are diagnosed at an advanced stage of disease for which limited treatment options are available. The only proven systemic therapy for advanced HCC is sorafenib, a multi-kinase inhibitor that has demonstrated modest efficacy and reasonable tolerability in patients with advanced HCC. Five years after the approval of sorafenib, no other agent has been proven to be beneficial in the first- or second-line setting in advanced HCC. While molecular studies have highlighted various potential targets in HCC, the mammalian target of rapamycin (mTOR) has emerged as an exciting target for cancer therapy including HCC. Laboratory data have linked the phosphatidylinositol 3-kinase/AKT/mTOR axis to various oncogenic processes, including survival and angiogenesis. Historically, mTOR inhibitors have been used for their immunosuppressive properties, but more recently they have been approved as anticancer agents. Retrospective HCC studies suggest that the inclusion of mTOR inhibition as part of an immunosuppressant regimen after transplantation may reduce HCC recurrence compared with other immunosuppressive agents such as calcineurin inhibitors. More recently, single-arm, phase I/II studies have shown that mTOR inhibitors also have activity as monotherapy in cases of recurrent HCC or de novo advanced HCC. This article will review the rationale for targeting the mTOR pathway in HCC, and the currently available clinical data supporting its development for HCC.