New therapeutic agents for chronic hepatitis B

Preclinical characterization of a novel potent core protein assembly modulator for the treatment of chronic hepatitis B viral infection

The hepatitis B virus (HBV) capsid or core protein is a promising drug target currently being investigated for potential curative therapies for chronic HBV infection. In this study, we performed extensive in vitro and in vivo characterization of a novel and potent HBV core protein assembly modulator (CpAM), CU15, for both anti-HBV activity and druggability properties. CU15 potently inhibited HBV DNA replication in in vitro HBV-infected HepG2.2.15 cells (EC50 of 8.6 nM), with a low serum shift. It was also effective in inhibiting HBV DNA and cccDNA formation in de novo HBV-infected primary human hepatocytes. Furthermore, CU15 was active across several HBV genotypes and across clinically relevant core protein variants. After oral administration to an in vivo HBV mouse model, CU15 significantly reduced plasma HBV DNA and RNA levels, at plasma exposure consistent with the estimated in vitro potency. In vitro, CU15 exhibited excellent passive permeability and relatively high metabolic stability in liver preparations across species (human > dog> rat). In vitro human liver microsomal studies suggest that the compound's major metabolic pathway is CYP3A-mediated oxidation. Consistent with the in vitro findings, CU15 is a compound with a low-to-moderate clearance and high oral bioavailability in rats and dogs. Based on the apparent in vitro-in vivo correlation observed, CU15 has the potential to exhibit low clearance and high oral bioavailability in humans. In addition, CU15 also showed low drug-drug interaction liability with an acceptable in vitro safety profile (IC50 > 10 µM).

Class A capsid assembly modulator apoptotic elimination of hepatocytes with high HBV core antigen level in vivo is dependent on de novo core protein translation

Capsid assembly is critical in the hepatitis B virus (HBV) life cycle, mediated by the viral core protein. Capsid assembly is the target for new anti-viral therapeutics known as capsid assembly modulators (CAMs) of which the CAM-aberrant (CAM-A) class induces aberrant shaped core protein structures and leads to hepatocyte cell death. This study aimed to identify the mechanism of action of CAM-A modulators leading to HBV-infected hepatocyte elimination where CAM-A-mediated hepatitis B surface antigen (HBsAg) reduction was evaluated in a stable HBV replicating cell line and in AAV-HBV-transduced C57BL/6, C57BL/6 SCID, and HBV-infected chimeric mice with humanized livers. Results showed that in vivo treatment with CAM-A modulators induced pronounced reductions in hepatitis B e antigen (HBeAg) and HBsAg, associated with a transient alanine amino transferase (ALT) increase. Both HBsAg and HBeAg reductions and ALT increase were delayed in C57BL/6 SCID and chimeric mice, suggesting that adaptive immune responses may indirectly contribute. However, CD8+ T cell depletion in transduced wild-type mice did not impact antigen reduction, indicating that CD8+ T cell responses are not essential. Transient ALT elevation in AAV-HBV-transduced mice coincided with a transient increase in endoplasmic reticulum stress and apoptosis markers, followed by detection of a proliferation marker. Microarray data revealed antigen presentation pathway (major histocompatibility complex class I molecules) upregulation, overlapping with the apoptosis. Combination treatment with HBV-specific siRNA demonstrated that CAM-A-mediated HBsAg reduction is dependent on de novo core protein translation. To conclude, CAM-A treatment eradicates HBV-infected hepatocytes with high core protein levels through the induction of apoptosis, which can be a promising approach as part of a regimen to achieve functional cure.

IMPORTANCE

Treatment with hepatitis B virus (HBV) capsid assembly modulators that induce the formation of aberrant HBV core protein structures (CAM-A) leads to programmed cell death, apoptosis, of HBV-infected hepatocytes and subsequent reduction of HBV antigens, which differentiates CAM-A from other CAMs. The effect is dependent on the de novo synthesis and high levels of core protein.

Current Status and Challenges in Anti-Hepatitis B Virus Agents Based on Inactivation/Inhibition or Elimination of Hepatitis B Virus Covalently Closed Circular DNA

There has been over half a century since the discovery of hepatitis B virus (HBV) to now, but approximately 300 million patients with chronic hepatitis B (CHB) still live in the world, resulting in about one million deaths every year. Although currently approved antivirals (e.g., nucleoside analogues) are effective at reducing HBV replication, they have almost no impact on the existing HBV covalently closed circular DNA (cccDNA) reservoir. HBV cccDNA is a critical obstacle to the complete elimination of the virus via antiviral therapy. The true cure of HBV infection requires the eradication of viral cccDNA from HBV-infected cells; thus, the development of new agents directly or indirectly targeting HBV cccDNA is urgently needed due to the limitations of current available drugs against HBV infection. In this regard, it is the major focus of current anti-HBV research worldwide via different mechanisms to either inactivate/inhibit (functional cure) or eliminate (complete cure) HBV cccDNA. Therefore, this review discussed and summarized recent advances and challenges in efforts to inactivate/silence or eliminate viral cccDNA using anti-HBV agents from different sources, such as small molecules (including epigenetic drugs) and polypeptides/proteins, and siRNA or gene-editing approaches targeting/attenuating HBV cccDNA via different mechanisms, as well as future directions that may be considered in efforts to truly cure chronic HBV infection. In conclusion, no breakthrough has been made yet in attenuating HBV cccDNA, although a number of candidates have advanced into the phase of clinical trials. Furthermore, the overwhelming majority of the candidates function to indirectly target HBV cccDNA. No outstanding candidate directly targets HBV cccDNA. Relatively speaking, CCC_R08 and nitazoxanide may be some of the most promising agents to clear HBV infection in small molecule compounds. Additionally, CRISPR-Cas9 systems can directly target HBV cccDNA for decay and demonstrate significant anti-HBV activity. Consequently, gene-editing approaches targeting HBV cccDNA may be one of the most promising means to achieve the core goal of anti-HBV therapeutic strategies. In short, more basic studies on HBV infection need to be carried out to overcome these challenges.

Di-Fluoro Azepane HBV Capsid Assembly Modulators

The protein that forms the inner shell of the HBV virus, known as the capsid core protein, plays a crucial role in allowing chronic HBV infections to persist. Studies have shown that disrupting the assembly of the capsid can effectively combat the virus, and small molecule drugs that target the HBV capsid assembly modulator (CAM) process have been successful in clinical trials. Herein is described a distinct series of di-fluoro azepane CAMs with exceptional potency, pharmacokinetic, and solubility properties.

Persistent hepatic IFN system activation in HBV-HDV infection determines viral replication dynamics and therapeutic response

Hepatitis delta virus (HDV), a satellite virus of HBV, is regarded as the most severe type of hepatitis virus because of the substantial morbidity and mortality. The IFN system is the first line of defense against viral infections and an essential element of antiviral immunity; however, the role of the hepatic IFN system in controlling HBV-HDV infection remains poorly understood. Herein, we showed that HDV infection of human hepatocytes induced a potent and persistent activation of the IFN system whereas HBV was inert in triggering hepatic antiviral response. Moreover, we demonstrated that HDV-induced constitutive activation of the hepatic IFN system resulted in a potent suppression of HBV while modestly inhibiting HDV. Thus, these pathogens are equipped with distinctive immunogenicity and varying sensitivity to the antiviral effectors of IFN, leading to the establishment of a paradoxical mode of viral interference wherein HDV, the superinfectant, outcompetes HBV, the primary pathogen. Furthermore, our study revealed that HDV-induced constitutive IFN system activation led to a state of IFN refractoriness, rendering therapeutic IFNs ineffective. The present study provides potentially novel insights into the role of the hepatic IFN system in regulating HBV-HDV infection dynamics and its therapeutic implications through elucidating the molecular basis underlying the inefficacy of IFN-based antiviral strategies against HBV-HDV infection.

HBx downregulated decorin and decorin-derived peptides inhibit the proliferation and tumorigenicity of hepatocellular carcinoma cells

Hepatitis B virus (HBV) is one of the important risk factors in inducing the occurrence and development of liver cancer, while the mechanism has not been fully clarified. In this study, we found decorin (DCN) was significantly reduced in HBV transgenic cell line HepG2-4D14 compared to HepG2. The data from hepatocellular carcinoma (HCC) patients indicated that the level of DCN mRNA was significantly lower in tumor tissues than healthy control and positively correlated with the survival of HCC patients. We revealed that HBV HBx can inhibit the transcription of DCN by blocking p53 activity. Functional analysis demonstrated that overexpression of DCN substantially inhibits the proliferation of HCC cells, while knockdown of DCN enhances the proliferation of HCC cells. It is known that DCN could competitively bind to c-Met to inhibit HGF/c-Met signaling pathway to inhibit the development of HCC. Therefore, we screened the novel antitumor peptides derived from DCN based on the sequence of DCN and the complex structure of HGF/c-Met with virtual screening and identified a set of DCN-derived peptides (DCN-Ps) which may competitively bind to c-Met. We found that 5 of peptides can reduce the proliferation and migration of HepG2 cells significantly. Among them, DCN-P#3 can inhibit the growth of HCC cells both in vitro and in vivo. In conclusion, we discovered that HBV HBx downregulates the expression of DCN, which in turn promotes the proliferation of hepatocytes and the development of HCC. We identified DCN-derived antitumor peptides which provides the candidates for developing novel drugs against HCC.

HBsAg (-)/HBsAb (-)/HBeAg (-)/HBeAb (+)/HBcAb (+) predicts a high risk of hepatitis B reactivation in patients with B-cell lymphoma receiving rituximab based immunochemotherapy

Patterns of hepatitis B virus reactivation (HBV-R) in HBsAg (-)/HBcAb (+) patients with B-cell non-Hodgkin lymphoma (NHL) receiving rituximab based immunochemotherapy have not been well described. The retrospective study included 222 HBsAg (-)/HBcAb (+) NHL patients as training cohort and 127 cases as validation cohort. The incidence of HBV-R in HBsAg (-)/HBcAb (+) B-cell NHL patients was 6.3% (14/222), of which that in HBsAg (-)/HBsAb (-)/HBeAg (-)/HBeAb (+)/HBcAb (+) population was 23.7% (9/38). Multivariate analysis showed that HBsAg (-)/HBsAb (-)/HBeAg (-)/HBeAb (+)/HBcAb (+) correlated with a high risk of HBV-R in B-cell lymphoma patients (training phase hazard ratio [HR], 10.123; 95% confidence interval [CI], 3.389-30.239; p < 0.001; validation phase HR, 18.619; 95% CI, 1.684-205.906; p = 0.017; combined HR, 12.264; 95% CI, 4.529-33.207; p < 0.001). In the training cohort, the mortality rate of HBsAg (-)/HBcAb (+) B-cell NHL caused by HBV-R was 14.3% (2/14) while that for HBV reactivated HBsAg (-)/HBsAb (-)/HBeAg (-)/HBeAb (+)/HBcAb (+) population was up to 44.4% (4/9). As a high incidence of HBV-R and high mortality after HBV-R was found in HBsAg (-)/HBsAb (-)/HBcAb (+)/HBeAg (-)/HBeAb (+) patients with B-cell NHL receiving rituximab based immunochemotherapy, prophylactic antiviral therapy is recommended for these patients.

Sustained viral response and relapse after discontinuation of oral antiviral drugs in HBeAg-positive patients with chronic hepatitis B infection

Objective

To investigate the sustained virological response and relapse in chronic hepatitis B (CHB) patients with hepatitis B e antigen (HBeAg) positive after stopping oral antiviral drugs, and to monitor the disease progression and the incidence of adverse events such as liver cirrhosis and hepatocellular carcinoma.

Methods

This is a prospective observational study. Patients who continued nucleos(t)ide analogue (NA) treatment after achieving HBeAg seroconversion for more than 3 years were enrolled. After signing the informed consent form, patients stopped NA treatment and received follow-up. During the follow-up, the antiviral treatment information of the patients was collected, and the follow-up observation was carried out every 3 months since the enrollment. We monitored the virological indexes, liver and kidney function, serology and liver imaging during follow-up. The purpose of this study was to explore the sustained virological response rate, HBV DNA recurrence rate, clinical relapse rate and the related factors after drug withdrawal.

Results

A total of 82 patients were enrolled, including 42 males (51.22%) and 40 females (48.78%), with a median age of 34.00 (31.00, 37.25) years. All enrolled patients were followed up for 1 year. At the end of the follow-up, 36.59% (30/82) of patients had sustained virological response, 63.41% (52/82) of patients had HBV DNA reactivation, 17.07% (14/82) of patients had clinical relapse, and 10.98% (9/82) of patients had HBeAg reversion. During the follow-up, there were no adverse events such as liver cirrhosis and hepatocellular carcinoma. The median level of hepatitis B surface antigen (HBsAg) in patients with sustained virological response was lower than that in patients with HBV DNA reactivation (2.92 vs.3.18 log₁₀IU/ml, Z=-1.492/P=0.136), and the median level of baseline HBsAg in patients with HBV DNA reactivation was lower than that in patients with clinical relapse (3.01 vs.3.45 log₁₀IU/mL, Z=-1.795/P=0.073), but the difference was not significant. There was no significant statistical difference between patients with sustained virological response and HBV DNA reactivation of the median total treatment time [69.50 (56.25, 86.00) vs.62.50 (44.00, 88.50) months, Z=-0.689/P=0.491], and the consolidation treatment time [41.50 (36.75, 54.75) vs.40.50 (36.00, 53.75) months, Z=-0.419/P=0.675].

Conclusion

The sustained virological response rate of HBeAg positive CHB patients after stopping oral antiviral treatment is lower, and it is more common in patients with lower HBsAg levels. Patients still need to be closely monitored after stopping NA therapy.

Diazepinone HBV Capsid Assembly Modulators

The HBV capsid core protein serves a number of important functions in the viral life cycle enabling chronic HBV infection to persist, and therefore is a promising drug target. Interfering with capsid assembly has shown efficacy in clinical trials with small molecule capsid assembly modulators (CAMs). Herein is described the further optimization of a progressive series of diazepinone HBV CAMs.

LINC01431 Promotes Histone H4R3 Methylation to Impede HBV Covalently Closed Circular DNA Transcription by Stabilizing PRMT1

Covalently closed circular DNA (cccDNA) is the transcriptional template of hepatitis B virus (HBV), which interacts with both host and viral proteins to form minichromosome in the nucleus and is resistant to antiviral agents. Identification of host factors involved in cccDNA transcriptional regulation is expected to prove a new venue for HBV therapy. Recent evidence suggests the involvement of long noncoding RNAs (lncRNAs) in mediating the interaction of host factors with various viruses, however, lncRNAs that HBV targets and represses cccDNA transcription have not been fully elucidated. Here, the authors identified LINC01431 as a novel host restriction factor for HBV transcription. Mechanically, LINC01431 competitively bound with type I protein arginine methyltransferase (PRMT1) to block the HBx-mediated PRMT1 ubiquitination and degradation. Consequently, LINC01431 increased the occupancy of PRMT1 on cccDNA, leading to enhanced H4R3me2a modification and reduced acetylation of cccDNA-bound histones, thereby repressing cccDNA transcription. In turn, to facilitate viral replication, HBV transcriptionally repressed LINC01431 expression by HBx-mediated repression of transcription factor Zinc fingers and homeoboxes 2 (ZHX2). Collectively, the study demonstrates LINC01431 as a novel epigenetic regulator of cccDNA minichromosome and highlights a feedback loop of HBx-LINC01431-PRMT1 in HBV replication, which provides potential therapeutic targets for HBV treatment.

Hepatitis B virus reactivation in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by proliferative synovitis, which can cause cartilage and bone damage as well as functional limitations. Disease-modifying anti-rheumatic drugs have significantly improved the prognosis of RA patients. However, people with RA, when combined with hepatitis B virus (HBV) infection, may experience reactivation of HBV during treatment with anti-rheumatic drugs. The outcome of HBV reactivation (HBVr) varies from liver inflammation to liver failure, while insufficient HBV screening in RA patients has been reported in various countries. Therefore, it is necessary to identify patients at high risk before starting immunosuppressive therapy. The immune response plays an important role in anti-HBV infection. However, most anti-rheumatic drugs exert an inhibitory effect on the body’s immune system, resulting in HBVr. Therefore, it is necessary to conduct a comprehensive evaluation based on host factors, viral factors, and drug factors. In this paper, we summarize the mechanism of HBVr, the risk of HBVr caused by anti-rheumatic drugs, and the appropriate diagnosis and treatment process for RA patients so that clinicians can have a more comprehensive understanding of HBVr in RA patients.

Oxadiazepinone HBV capsid assembly modulators

The HBV core protein serves multiple essential functions in the viral life cycle that enable chronic HBV infection to persist, and as such, represents a promising drug target. Modulation of the HBV capsid assembly has shown efficacy in early clinical trials through use of small molecule capsid assembly modulators (CAMs). Herein is described the evolution and SAR of a novel pyrazolo piperidine lead series into advanced oxadiazepinone HBV CAMs.

Functional cure for chronic hepatitis B: accessibility, durability, and prognosis

Hepatitis B surface antigen (HBsAg) clearance is regarded as the ideal endpoint for antiviral treatment in terms of drug withdrawal safety and improvements in prognosis. However, the overall rate of HBsAg clearance is low and differs based on treatment method and course. The recent application of combined and extended treatment strategies have improved the HBsAg clearance rate, and several patients achieved HBsAg clearance in clinical treatment. In addition, the durability of and clinical outcomes after HBsAg clearance have become the focus of both researchers and clinicians. This article reviews HBsAg clearance in terms of accessibility, durability, improvements in prognosis and relevant advances.

Identification of a new class of HBV capsid assembly modulator

The HBV core protein is a druggable target of interest due to the multiple essential functions in the HBV life cycle to enable chronic HBV infection. The core protein oligomerizes to form the viral capsid, and modulation of the HBV capsid assembly has shown efficacy in clinical trials. Herein is described the identification and hit to lead SAR of a novel series of pyrazolo piperidine HBV capsid assembly modulators.

Virology analysis of chronic hepatitis B virus-infected patients treated for 28 days with JNJ-56136379 monotherapy

Four weeks of once-daily oral JNJ-56136379 (JNJ-6379; 25, 75, 150 or 250 mg), a class-N capsid assembly modulator (CAM-N), was well tolerated with potent antiviral activity in treatment-naïve, chronic hepatitis B e antigen-positive and hepatitis B e antigen-negative patients (NCT02662712). Hepatitis B virus (HBV) genome sequence analysis, using HBV DNA next-generation sequence technology, was performed, and impact of substitutions on efficacy was assessed. Analyses focused on HBV core protein amino acid positions associated with JNJ-6379 and/or other CAMs in vitro resistance, and those within the CAM-binding pocket. 31/57 patients had ≥ 1 polymorphism at any of the core amino acid positions of interest, most frequently at positions 38 (32%), 105 (23%) and 109 (14%). None of these polymorphisms are known to reduce JNJ-6379 in vitro activity (fold change [FC] in 50% effective concentration <3.0). Two JNJ-6379-treated patients carried a Y118F baseline core polymorphism known to reduce JNJ-6379 activity in vitro (FC = 6.6) and had HBV DNA declines of 2.77 (75 mg) and 2.19 log₁₀ IU/mL (150 mg) at the end of treatment. One 75 mg JNJ-6379-treated patient had an emerging T109S substitution (FC = 1.8; HBV DNA decline 3.18 log₁₀ IU/mL). A 25 mg JNJ-6379-treated patient had on-treatment enrichment of Y118F variant (HBV DNA decline 2.13 log₁₀ IU/mL). In conclusion, baseline polymorphisms and enrichment of substitutions reducing JNJ-6379 in vitro activity were rare, with no consistent impact on virological response during a 4-week phase 1b study. Emergence of resistance to longer treatments of JNJ-6379 will be evaluated in phase 2 studies.

Potential Drug Targets Against Hepatitis B Virus Based on Both Virus and Host Factors

BACKGROUND

Hepatitis B is a very harmful and epidemic disease caused by hepatitis B virus (HBV). Although an effective anti-HBV vaccine is available, chronic infection poses still a huge health burden in the whole world. The present anti-HBV drugs including nucleoside analogues and interferonalpha have their limitations without exception. There is no effective drug and therapeutic method that can really and truly cure hepatitis B so far. The variability of HBV genome results in that a significant number of patients develop drug resistance during the long-term use of anti-HBV drugs. Hence, it is urgently needed to discover novel targets and develop new drugs against hepatitis B.

OBJECTIVE

The review aims to provide the theory support for designing of the anti-HBV innovative drugs by offering a summary of the current situation of antiviral potential targets.

RESULTS AND CONCLUSION

Since HBV is obligate intracellular parasite, and as such it depends on host cellular components and functions to replicate itself. The targeting both virus and host might be a novel therapeutic option for hepatitis B. Accordingly, we analyse the advances in the study of the potential drug targets for anti-HBV infection, focusing on targeting virus genome, on targeting host cellular functions and on targeting virus-host proteins interactions, respectively. Meanwhile, the immune targets against chronic hepatitis B are also emphasized. In short, the review provides a summary of antiviral therapeutic strategies to target virus factors, host factors and immune factors for future designing of the innovative drug against HBV infection.

Advanced Therapeutics, Vaccinations, and Precision Medicine in the Treatment and Management of Chronic Hepatitis B Viral Infections; Where Are We and Where Are We Going?

The management of chronic hepatitis B virus (CHB) infection is an area of massive unmet clinical need worldwide. In spite of the development of powerful nucleoside/nucleotide analogue (NUC) drugs, and the widespread use of immune stimulators such as interferon-alpha (IFNα) or PEGylated interferon-alpha (PEG-IFNα), substantial improvements in CHB standards of care are still required. We believe that the future for CHB treatment now rests with advanced therapeutics, vaccination, and precision medicine, if all are to bring under control this most resilient of virus infections. In spite of a plethora of active drug treatments, anti-viral vaccinations and diagnostic techniques, the management of CHB infection remains unresolved. The reason for this is the very complexity of the virus replication cycle itself, giving rise to multiple potential targets for therapeutic intervention some of which remain very intractable indeed. Our review is focused on discussing the potential impact that advanced therapeutics, vaccinations and precision medicine could have on the future management of CHB infection. We demonstrate that advanced therapeutic approaches for the treatment of CHB, in the form of gene and immune therapies, together with modern vaccination strategies, are now emerging rapidly to tackle the limitations of current therapeutic approaches to CHB treatment in clinic. In addition, precision medicine approaches are now gathering pace too, starting with personalized medicine. On the basis of this, we argue that the time has now come to accelerate the design and creation of precision therapeutic approaches (PTAs) for CHB treatment that are based on advanced diagnostic tools and nanomedicine, and which could maximize CHB disease detection, treatment, and monitoring in ways that could genuinely eliminate CHB infection altogether.

Antiviral Properties and Mechanism of Action Studies of the Hepatitis B Virus Capsid Assembly Modulator JNJ-56136379

Capsid assembly is a critical step in the hepatitis B virus (HBV) life cycle, mediated by the core protein. Core is a potential target for new antiviral therapies, the capsid assembly modulators (CAMs). JNJ-56136379 (JNJ-6379) is a novel and potent CAM currently in phase II trials. We evaluated the mechanisms of action (MOAs) and antiviral properties of JNJ-6379 in vitro Size exclusion chromatography and electron microscopy studies demonstrated that JNJ-6379 induced the formation of morphologically intact viral capsids devoid of genomic material (primary MOA). JNJ-6379 accelerated the rate and extent of HBV capsid assembly in vitro JNJ-6379 specifically and potently inhibited HBV replication; its median 50% effective concentration (EC50) was 54 nM (HepG2.117 cells). In HBV-infected primary human hepatocytes (PHHs), JNJ-6379, when added with the viral inoculum, dose-dependently reduced extracellular HBV DNA levels (median EC50 of 93 nM) and prevented covalently closed circular DNA (cccDNA) formation, leading to a dose-dependent reduction of intracellular HBV RNA levels (median EC50 of 876 nM) and reduced antigen levels (secondary MOA). Adding JNJ-6379 to PHHs 4 or 5 days postinfection reduced extracellular HBV DNA and did not prevent cccDNA formation. Time-of-addition PHH studies revealed that JNJ-6379 most likely interfered with postentry processes. Collectively, these data demonstrate that JNJ-6379 has dual MOAs in the early and late steps of the HBV life cycle, which is different from the MOA of nucleos(t)ide analogues. JNJ-6379 is in development for chronic hepatitis B treatment and may translate into higher HBV functional cure rates.

Pharmacokinetics of a weekly transdermal delivery system of tenofovir alafenamide in hairless rats

Tenofovir alafenamide (TAF) is a potent prodrug of tenofovir (TFV) for HIV prophylaxis, and HIV and HBV treatment. Compared to oral daily doses, transdermal administration of TAF may be more advantageous for long-term adherence by offering sustained drug delivery and reduced dosing frequency. Here, we described the plasma pharmacokinetics (PK) of an optimized once-weekly suspension transdermal delivery system (TDS) for TAF (96 mg/25 cm² of TDS) in female hairless rats. Over the study period, the TAF TDS delivered an overall low level of TAF (median: 1.43 [0.02-3.28] ng/mL) and a sustained level of the stable metabolite and parent drug, TFV. Relative to the projected exposure corresponding to six-day oral daily doses, a comparable TAF exposure but a substantially lower TFV exposure was resulted from the TAF TDS, suggesting a lower risk of TFV-associated adverse effects. TAF, TFV, and phosphorylated TFVs (TFV-monophosphate and diphosphate) were found distributed in vaginal tissue, the portal of entry for HIV during male-to-female sexual transmission. Skin adhesion and tolerance were acceptable given the animal model used. PK evaluation of the TAF TDS in hairless rats demonstrates the proof of concept that transdermal delivery can be an alternative route for a sustained, once-weekly systemic delivery of TAF.

Hepatitis B Virus Infection: Overview

Hepatitis B virus (HBV) is a DNA virus, belonging to the Hepadnaviridae family. It is a partially double-stranded DNA virus with a small viral genome (3.2 kb). Chronic HBV infection remains a global public health problem. If left untreated, chronic HBV infection can progress to end-stage liver disease, such as liver cirrhosis and hepatocellular carcinoma (HCC). In recent years, tremendous advances in the field of HBV basic and clinical research have been achieved, ranging from the HBV biological characteristics, immunopathogenesis, and animal models to the development of new therapeutic strategies and new drugs against HBV. In this overview, we begin with a brief history of HBV discovery and treatment milestones. We then briefly summarize the HBV research advances, which will be detailed in the following chapters.

Present and Future Therapies for Chronic Hepatitis B

Chronic hepatitis B (CHB) remains the leading cause of liver-related morbidity and mortality across the world. If left untreated, approximately one-third of these patients will progress to severe end-stage liver diseases including liver failure, cirrhosis, and hepatocellular carcinoma (HCC). High level of serum HBV DNA is strongly associated with the development of liver failure, cirrhosis, and HCC. Therefore, antiviral therapy is crucial for the clinical management of CHB. Current antiviral drugs including nucleoside/nucleotide analogues (NAs) and interferon-α (IFN-α) can suppress HBV replication and reduce the progression of liver disease, thus improving the long-term outcomes of CHB patients. This chapter will discuss the standard and optimization antiviral therapies in treatment-naïve and treatment-experienced patients, as well as in the special populations. The up-to-date advances in the development of new anti-HBV agents will be also discussed. With the combination of the current antiviral drugs and the newly developed antiviral agents targeting the different steps of the viral life cycle or the newly developed agents modulating the host immune responses, the ultimate eradication of HBV will be achieved in the future.

Restoring, releasing or replacing adaptive immunity in chronic hepatitis B

Multiple new therapeutic approaches are currently being developed to achieve sustained, off-treatment suppression of HBV, a persistent hepatotropic infection that kills ~2,000 people a day. A fundamental therapeutic goal is the restoration of robust HBV-specific adaptive immune responses that are able to maintain prolonged immunosurveillance of residual infection. Here, we provide insight into key components of successful T cell and B cell responses to HBV, discussing the importance of different specificities and effector functions, local intrahepatic immunity and pathogenic potential. We focus on the parallels and interactions between T cell and B cell responses, highlighting emerging areas for future investigation. We review the potential for different immunotherapies in development to restore or release endogenous adaptive immunity by direct or indirect approaches, including limitations and risks. Finally, we consider an alternative HBV treatment strategy of replacing failed endogenous immunity with infusions of highly targeted T cells or antibodies.

Safety and immunogenicity of the therapeutic vaccine TG1050 in chronic hepatitis B patients: a phase 1b placebo-controlled trial

Treatment of chronic hepatitis B (CHB) typically requires life-long administration of drugs. Cohort and pre-clinical studies have established the link between a functional T-cell-mounted immunity and resolution of infection. TG1050 is an adenovirus 5-based vaccine that expresses HBV polymerase and domains of core and surface antigen and has shown immunogenicity and antiviral effects in mice. We performed a phase 1 clinical trial to assess safety and explore immunogenicity and early efficacy of TG1050 in CHB patients. This randomized, double blind, placebo-controlled study included two sequential phases: one single dose cohort (SD, n = 12) and one multiple (3) doses cohort (MD, n = 36). Patients, virally suppressed under nucleoside(d)tide analog NUC therapy, were randomized 1:1:1 across 3 dose levels (DL) and assigned to receive 10⁹, 10¹⁰, 10¹¹ virus particles (vp) of TG1050 and then randomized within each DL to placebo (3:1 and 9:3 vaccines/placebo in each DL, respectively, for the SD and MD cohorts). Cellular (ELISPOT) and antibody responses (anti-Adenovirus), as well as evolution of circulating HBsAg and HBcrAg, were monitored. All doses were well tolerated in both cohorts, without severe adverse event. TG1050 was capable to induce IFN-γ producing T-cells targeting 1 to 3 encoded antigens, in particular at the 10¹⁰vp dose. Overall, minor decreases of HBsAg were observed while a number of vaccinees reached unquantifiable HBcrAg by end of the study. In CHB patients under NUC, TG1050 exhibited a good safety profile and was capable to induce HBV-specific cellular immune response. These data support further clinical evaluation, especially in combination studies.

Quantitative of serum hepatitis B core antibody is a potential predictor of recurrence after interferon-induced hepatitis B surface antigen clearance

BACKGROUND

Recurrence is common for patients with chronic hepatitis B (CHB) who achieved hepatitis B virus (HBV) surface antigen (HBsAg) clearance after antiviral treatment. The aim of the study is to explore the possibility of quantitative hepatitis B core antibody (Anti-HBc) level as a biomarker to predict recurrence.

METHODS

A total of 73 patients with HBsAg clearance were enrolled in this study, 16 cases with recurrence and 57 cases of non-recurrence. A newly developed double-sandwich Anti-HBc immunoassay was used to detect the quantitative Anti-HBc level before therapy (baseline) and at the end of therapy. Logistic regression analysis was used to evaluate the predictive ability of quantitative Anti-HBc levels for recurrence.

RESULTS

Quantitative Anti-HBc levels at the end of therapy in both recurrence and non-recurrence groups were significantly lower than those of before therapy (P < 0.001). In addition, the declining trend of the recurrence group was significantly greater than that of the non-recurrence group (0.71 log10 vs. 0.45 log10 IU/mL, P = 0.026). Quantitative Anti-HBc levels in non-recurrence group were higher than those in recurrence group at baseline and drug withdrawal (P = 0.023, P < 0.001). Multivariable analysis showed that Anti-HBc level at drug withdrawal alone was associated with recurrence (OR = 0.116, P = 0.037). At Anti-HBc level >2.3386 log10 IU/mL, the predictive sensitivity and specificity for recurrence were 80.0% and 71.9%.

CONCLUSIONS

Quantitative Anti-HBc level can be used as a potential predictor of recurrence after HBsAg clearance. Anti-HBc level at the drug withdrawal has better predictive value than the baseline.

Antiviral treatment for chronic hepatitis B: Safety, effectiveness, and prognosis

The goal of chronic hepatitis B (CHB) therapy is to improve the patient prognosis through the sustained inhibition of viral replication. However, due to the uncertainty and potentially unlimited duration of the treatment course, nucleus(t)ide analogue (NA) resistance and safety, financial costs and patient compliance, different endpoints of antiviral treatment have been proposed in CHB prevention and treatment guidelines. Different treatment endpoints are closely associated with the safety of drug withdrawal and improvements in prognosis. Antiviral treatment suppresses HBV DNA replication, drug withdrawal leads to relapse, and long-term treatment causes drug safety and resistance issues. Although hepatitis B e antigen seroconversion based on HBV DNA inhibition is considered as “a satisfactory endpoint”, drug withdrawal still leads to high relapse rates. Hepatitis B surface antigen (HBsAg) clearance is the “ideal endpoint” in terms of the safety of drug withdrawal and improvements in prognosis. However, the HBsAg clearance rate is low using the conventional single drug treatment and fixed course regimens. Recently, the application of an “optimized antiviral treatment strategy” has improved the HBsAg clearance rate, and make an “ideal endpoint” possible. This article reviews the different antiviral treatment endpoints in terms of the safety of drug withdrawal, improvements in prognosis and relevant advances.

Liver fibrosis markers as assessed by ultrasound elastography and serum samples: A large comparative study in hepatitis virus B and C liver diseases

AIM

We aimed to compare the well-established liver fibrosis (LF) markers in Japanese patients with chronic hepatitis B (CHB, n = 331) and chronic hepatitis C (CHC, n = 886) and to discuss possible causes of differences in results between CHB patients and CHC patients.

METHODS

Virtual touch quantification (VTQ) in acoustic radiation force impulse, Fibrosis-4 (Fib-4) index, aspartate aminotransferase to platelet ratio index (APRI), and hyaluronic acid (HA) were compared between the two cohorts. As an additional investigation, total collagen proportional area (TCPA, %) was tested using liver pathological samples (n = 83).

RESULTS

Significant LF (F2 or greater) and advanced LF (F3 or greater) were identified in 153 (46.2%) and 76 (23.0%) patients in the CHB cohort and 579 (65.3%) and 396 (44.7%) patients in the CHC cohort. The median VTQ, Fib-4 index, APRI, and HA values in the CHB cohort were 1.20 m/s, 1.36, 0.44, and 25 ng/mL; those in the CHC cohort were 1.32 m/s, 2.60, 0.74, and 65.5 ng/mL (P-values, all <0.0001). Similar tendencies were noted by F stage-based stratification. The median TCPA in the CHB cohort and the CHC cohort were 8.5% and 12.7% (P < 0.0006). The TCPA values in the CHC cohort were higher than those in the CHB cohort regardless of LF stage.

CONCLUSION

Values of LF markers in CHB patients can differ from those in CHC patients even in the same LF stage. Difference in total amount of collagen fiber in CHB and CHC appears to be linked to the difference.

The cyclophilin inhibitor CRV431 inhibits liver HBV DNA and HBsAg in transgenic mice

Hepatitis B virus (HBV) infection is a major health burden worldwide with 240 million chronically infected individuals. Nucleos(t)ide analogs and interferons are the current standards of care due to their suppression of HBV replication, but the treatments rarely eradicate HBV from individuals. Similar to current treatments for human immunodeficiency virus type-1 (HIV-1) and hepatitis C virus (HCV) patients, improved HBV therapies will require the combination of multiple drugs which target distinct steps of the HBV life cycle. In this study, we tested the potential of a cyclophilin inhibitor, CRV431, to affect HBV replication in transgenic mice. We found that oral treatment with CRV431 (50 mg/kg/day) for a period of 16 days significantly reduced liver HBV DNA levels and moderately decreased serum HBsAg levels. We observed an additive inhibitory effect on liver HBV DNA levels in mice treated with a combination of low doses of CRV431 (10 mg/kg/day) and the nucleotide prodrug, tenofovir exalidex (TXL), (5 mg/kg/day). No toxicity was observed in CRV431-treated mice. Although it is well known that CRV431 neutralizes the peptidyl-prolyl isomerase activity of cyclophilins, its anti-HBV mechanism(s) of action remains unknown. Nevertheless, this study provides the first demonstration of a beneficial effect of a cyclophilin inhibitor in vivo in an HBV transgenic mouse model. Altogether our data reveal the potential of CRV431 to be part of improved new therapies for HBV patients.

Identification of a quadruple mutation that confers tenofovir resistance in chronic hepatitis B patients

BACKGROUND & AIMS

Tenofovir disoproxil fumarate (TDF) is one the most potent nucleot(s)ide analogues for treating chronic hepatitis B virus (HBV) infection. Phenotypic resistance caused by genotypic resistance to TDF has not been reported. This study aimed to characterize HBV mutations that confer tenofovir resistance.

METHODS

Two patients with viral breakthrough during treatment with TDF-containing regimens were prospectively enrolled. The gene encoding HBV reverse transcriptase was sequenced. Eleven HBV clones harboring a series of mutations in the reverse transcriptase gene were constructed by site-directed mutagenesis. Drug susceptibility of each clone was determined by Southern blot analysis and real-time PCR. The relative frequency of mutants was evaluated by ultra-deep sequencing and clonal analysis.

RESULTS

Five mutations (rtS106C [C], rtH126Y [Y], rtD134E [E], rtM204I/V, and rtL269I [I]) were commonly found in viral isolates from 2 patients. The novel mutations C, Y, and E were associated with drug resistance. In assays for drug susceptibility, the IC₅₀ value for wild-type HBV was 3.8 ± 0.6 µM, whereas the IC₅₀ values for CYE and CYEI mutants were 14.1 ± 1.8 and 58.1 ± 0.9 µM, respectively. The IC₉₀ value for wild-type HBV was 30 ± 0.5 µM, whereas the IC₉₀ values for CYE and CYEI mutants were 185 ± 0.5 and 790 ± 0.2 µM, respectively. Both tenofovir-resistant mutants and wild-type HBV had similar susceptibility to the capsid assembly modulator NVR 3-778 (IC₅₀ <0.4 µM vs. IC₅₀ = 0.4 µM, respectively).

CONCLUSIONS

Our study reveals that the quadruple (CYEI) mutation increases the amount of tenofovir required to inhibit HBV by 15.3-fold in IC₅₀ and 26.3-fold in IC₉₀. These results demonstrate that tenofovir-resistant HBV mutants can emerge, although the genetic barrier is high.

LAY SUMMARY

Tenofovir is the most potent nucleotide analogue for the treatment of chronic hepatitis B virus infection and there has been no hepatitis B virus mutation that confers >10-fold resistance to tenofovir up to 8 years. Herein, we identified, for the first time, a quadruple mutation that conferred 15.3-fold (IC₅₀) and 26.3-fold (IC₉₀) resistance to tenofovir in 2 patients who experienced viral breakthrough during tenofovir treatment.

What Comes First: Treatment of Viral Hepatitis or Liver Cancer?

Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection are the most important underlying causes for the development of hepatocellular carcinoma (HCC) worldwide. Determining the optimal approach for management of the viral infection and the HCC depends on the virus and the stage of the cancer. In patients with HCV-associated HCC, there are multiple reasons to first treat the HCC. Firstly, in case of a curable HCC, the urgency for HCC treatment is important to avoid progression during HCV treatment. Secondly, the presence of HCC itself appears to reduce the rates of sustained virological response (SVR) achieved with direct-acting antivirals (DAAs). And finally, the evidence does not support the concept of an increase in HCC recurrence due to DAAs, so a patient can safely be treated after HCC cure. For patients with very advanced HCC, the benefits of HCV therapy are questionable. In contrast, those who develop HCC in the setting of chronic HBV infection, treatment with nucleoside analogues (NAs) is recommended prior to treating HCC, to prevent further liver injury and reduce the risk for HCC recurrence. Ultimately, earlier diagnosis and treatment of HBV and HCV will hopefully reduce the incidence of HCC worldwide.

Control of viral infections by epigenetic-targeted therapy

Epigenetics is defined as the science that studies the modifications of gene expression that are not owed to mutations or changes in the genetic sequence. Recently, strong evidences are pinpointing toward a solid interplay between such epigenetic alterations and the outcome of human cytomegalovirus (HCMV) infection. Guided by the previous possibly promising experimental trials of human immunodeficiency virus (HIV) epigenetic reprogramming, the latter is paving the road toward two major approaches to control viral gene expression or latency. Reactivating HCMV from the latent phase ("shock and kill" paradigm) or alternatively repressing the virus lytic and reactivation phases ("block and lock" paradigm) by epigenetic-targeted therapy represent encouraging options to overcome latency and viral shedding or otherwise replication and infectivity, which could lead eventually to control the infection and its complications. Not limited to HIV and HCMV, this concept is similarly studied in the context of hepatitis B and C virus, herpes simplex virus, and Epstein-Barr virus. Therefore, epigenetic manipulations stand as a pioneering research area in modern biology and could constitute a curative methodology by potentially consenting the development of broad-spectrum antivirals to control viral infections in vivo.

Sequence-encoded quantitative invader assay enables highly sensitive hepatitis B virus DNA quantification in a single tube without the use of a calibration curve

Absolute quantification of HBV-DNA by sequence-encoded Quantitative Invader assay in a single tube without using calibration curves.

Hepatitis B Virus-Upregulated LNC-HUR1 Promotes Cell Proliferation and Tumorigenesis by Blocking p53 Activity

Recent studies have indicated that a number of long noncoding RNAs (lncRNAs) are dysregulated in hepatocellular carcinoma, while their aberrant expressions are associated with tumorigenesis and poor prognosis. To identify hepatitis B virus (HBV)-related lncRNAs, we used RNA deep sequencing to quantify the abundances of lncRNAs in HepG2 cells and HBV transgenic HepG2-4D14 cells. Here, we demonstrate that lnc-HUR1 is significantly upregulated in HepG2-4D14 cells. We found that HBV-encoded hepatitis B x protein can enhance the transcription of lnc-HUR1. Overexpression of lnc-HUR1 promotes cell proliferation, whereas knockdown of lnc-HUR1 inhibits cell growth. We identified that lnc-HUR1 can interact with p53 and inhibit its transcriptional regulation on downstream genes, such as p21 and B cell lymphoma 2-associated X protein. We generated lnc-HUR1 transgenic mice and performed the partial hepatectomy (PHx) to examine liver regeneration. The data showed that the ratio of liver weight to body weight in lnc-HUR1 transgenic mice is higher than that in wild-type (WT) littermates at day 2 and day 3 following hepatectomy. Consistently, the results of bromodeoxyuridine staining on liver sections following hepatectomy indicate that the ratio of bromodeoxyuridine-positive cells in lnc-HUR1 transgenic mice is significantly higher than that in WT mice, suggesting that lnc-HUR1 promotes cell proliferation during liver regeneration. Next, we performed the experiment of diethylnitrosamine-induced tumorigenesis. The data demonstrate that tumor number in lnc-HUR1 transgenic mice is higher compared with control mice, indicating that lnc-HUR1 enhances diethylnitrosamine-induced tumorigenesis. Conclusion: We reveal that HBV-upregulated lnc-HUR1 promotes cell proliferation and tumorigenesis by interacting with p53 to block downstream gene transcription. Our findings suggest that lnc-HUR1 plays an important role in HBV-related hepatocellular carcinoma development and may serve as a therapeutic marker for hepatocellular carcinoma. (Hepatology 2018; 00:000-000).

Bona fide receptor for hepatitis B and D viral infections: Mechanism, research models and molecular drug targets

Hepatitis B infections have become a serious public health issue globally, and the current first-line antiviral treatment for this disease is not a true cure. Recently, sodium taurocholate cotransporting polypeptide (NTCP), a liver-specific bile acid transporter, was identified as a bona fide receptor for hepatitis B virus (HBV) and its satellite virus, hepatitis delta virus (HDV). Identification of the HBV receptor has led to the development of robust cell cultures and provides a potential target for new treatments. This review summarizes the process by which NTCP was discovered and describes its clinical significance as the receptor for HBV and HDV entry.

Cure Strategies for Hepatitis B Virus: The Promise of Immunotherapy

Chronic hepatitits B virus remains a public health challenge, infecting more than 240 million people globally and causing 600,000 deaths per year from end-stage liver disease and/or hepatocellular carcinoma. Current antiviral therapeutic agents are highly effective at blocking viral replication, but discontinuation of therapy prior to loss of hepatitis B surface antigen generally leads to relapse. New modalities that target host factors of viral persistence such as immune response pathway inhibition hold promise. Other experimental approaches may target virally related persistence factors, including covalently closed circular DNA. All these approaches will require creative new means of assessing proof of biology and proof of mechanism, particularly in the relevant compartment of liver tissue. Furthermore, it is likely to require combinations of modalities in defined patient populations to achieve optimal response. A precompetitive consortium approach may enable companies, regulators, and academic researchers to share best practices and evaluate preclinical and clinical pathways for these novel approaches.

Ideal Cure for Hepatitis B Infection: The Target is in Sight

Hepatitis B virus (HBV) is one of the most common causes of liver cirrhosis and hepatocellular carcinoma. Despite recent strides in pharmacotherapy, complete cure of HBV infection still remains an enigma. The biggest obstacle in HBV therapy is clearance of covalently closed circular deoxyribonucleic acid (cccDNA). We discuss about the role of cccDNA in HBV life cycle, efficacy and shortcomings of currently available antivirals as well as promising novel targets to achieve ideal HBV cure.

Sequential therapy involving an early switch from entecavir to pegylated interferon-α in Japanese patients with chronic hepatitis B

AIM

The optimal combination of two currently available agents with different mechanisms of action, a nucleos(t)ide analog and pegylated interferon-α (PegIFNα), must be determined to improve treatment of chronic hepatitis B (CHB).

METHODS

In this study, 24 patients with CHB (14 hepatitis B envelope antigen [HBeAg]-positive patients and 10 HBeAg-negative patients) received entecavir for 36-52 weeks, followed by entecavir plus Peg-IFNα2a for 4 weeks, and finally by PegIFNα-2a alone for 44 weeks.

RESULTS

A sustained biochemical, virologic, and serologic response was obtained in 7/24 (29%) patients at 48 weeks post-treatment (2/14 [14%] in HBeAg-positive vs 5/10 [50%] in HBeAg-negative patients, P = 0.085). At baseline, patients with a sustained response had a significantly lower γ-glutamyl transferase level (P = 0.0023), a lower aspartate aminotransferase-to-platelet ratio index (P = 0.049), and a lower α-fetoprotein level (P = 0.042) than those without a sustained response. The decline in hepatitis B surface antigen (HBsAg) levels during the first 24 weeks of PegIFNα-2a treatment in patients with a sustained response was greater than that in patients without (P = 0.017). Additionally, HBsAg seroclearance was achieved in two patients (8.3%): one HBeAg-positive and one HBeAg-negative patient.

CONCLUSION

The outcomes of sequential therapy involving an early switch from entecavir to PegIFNα-2a were unsatisfactory in Japanese patients with CHB. In addition to viral factors, host metabolic characteristics and liver fibrosis/tumor markers can be used for prediction of a sustained response to therapy, but accurate prediction of the therapeutic response is difficult.

Gene Therapy for Chronic HBV-Can We Eliminate cccDNA?

Chronic infection with the hepatitis B virus (HBV) is a global health concern and accounts for approximately 1 million deaths annually. Amongst other limitations of current anti-HBV treatment, failure to eliminate the viral covalently closed circular DNA (cccDNA) and emergence of resistance remain the most worrisome. Viral rebound from latent episomal cccDNA reservoirs occurs following cessation of therapy, patient non-compliance, or the development of escape mutants. Simultaneous viral co-infections, such as by HIV-1, further complicate therapeutic interventions. These challenges have prompted development of novel targeted hepatitis B therapies. Given the ease with which highly specific and potent nucleic acid therapeutics can be rationally designed, gene therapy has generated interest for antiviral application. Gene therapy strategies developed for HBV include gene silencing by harnessing RNA interference, transcriptional inhibition through epigenetic modification of target DNA, genome editing by designer nucleases, and immune modulation with cytokines. DNA-binding domains and effectors based on the zinc finger (ZF), transcription activator-like effector (TALE), and clustered regularly interspaced short palindromic repeat (CRISPR) systems are remarkably well suited to targeting episomal cccDNA. This review discusses recent developments and challenges facing the field of anti-HBV gene therapy, its potential curative significance and the progress towards clinical application.

Defective T-cell immunity in hepatitis B virus infection: why therapeutic vaccination needs a helping hand

Hepatitis B virus (HBV) remains a major cause of morbidity and mortality worldwide. Treatments that can induce functional cure in patients chronically infected with this hepatotropic, non-cytopathic virus are desperately needed. Attempts to use therapeutic vaccines to expand the weak antiviral T-cell response and induce sustained immunity have been unsuccessful. However, exciting progress has been made in defining the molecular defects that must be overcome to harness T-cell immunity. A large arsenal of immunotherapeutic agents and direct-acting antivirals targeting multiple steps of the viral lifecycle is emerging. In this Review, we discuss how to translate the new insights into T-cell manipulation, combined with better understanding of patient heterogeneity, into optimisation of therapeutic vaccines against HBV. We review the opportunities and risks involved in boosting endogenous T-cell responses using combinations of next generation therapeutic vaccines and immunotherapy agents.

A meta-analysis of the antiviral activity of the HBV-specific immunotherapeutic TG1050 confirms its value over a wide range of HBsAg levels in a persistent HBV pre-clinical model

Pre-clinical models mimicking persistent hepatitis B virus (HBV) expression are seldom, do not capture all features of a human chronic infection and due to their complexity, are subject to variability. We report a meta-analysis of seven experiments performed with TG1050, an HBV-targeted immunotherapeutic,¹ in an HBV-persistent mouse model based on the transduction of mice by an adeno-associated virus coding for an infectious HBV genome (AAV-HBV). To mimic the clinical diversity seen in HBV chronically infected patients, AAV-HBV transduced mice displaying variable HBsAg levels were treated with TG1050. Overall mean percentages of responder mice, displaying decrease in important clinical parameters i.e. HBV-DNA (viremia) and HBsAg levels, were 52% and 51% in TG1050 treated mice, compared with 8% and 22%, respectively, in untreated mice. No significant impact of HBsAg level at baseline on response to TG1050 treatment was found. TG1050-treated mice displayed a significant shorter Time to Response (decline in viral parameters) with an Hazard Ratio (HR) of 8.3 for viremia and 2.6 for serum HBsAg. The mean predicted decrease for TG1050-treated mice was 0.5 log for viremia and 0.8 log for HBsAg, at the end of mice follow-up, compared to no decrease for viremia and 0.3 log HBsAg decrease for untreated mice. For mice receiving TG1050, a higher decline of circulating viremia and serum HBsAg level over time was detected by interaction term meta-analysis with a significant treatment effect (p = 0.002 and p<0.001 respectively). This meta-analysis confirms the therapeutic value of TG1050, capable of exerting potent antiviral effects in an HBV-persistent model mimicking clinical situations.

A cell-penetrating whole molecule antibody targeting intracellular HBx suppresses hepatitis B virus via TRIM21-dependent pathway

Rationale: Monoclonal antibodies (mAbs) mostly targeting extracellular or cell surface molecules have been widely used in the treatment of various diseases. However, mAbs cannot pass through the cell membrane as efficiently as small compounds, thus limiting their use against intracellular targets. Methods to shuttle antibodies into living cells may largely expand research and application in areas based on mAbs. Hepatitis B virus X protein (HBx) is an important intracellular multi-functional viral protein in the life cycle of hepatitis B virus (HBV). HBx plays essential roles in virus infection and replication and is strongly associated with HBV-related carcinogenesis.

Methods: In this study, we developed a cell-penetrating whole molecule antibody targeting HBx (9D11-Tat) by the fusion of a cell penetrating peptide (CPP) on the C-terminus of the heavy chain of a potent mAb specific to HBx (9D11). The anti-HBV effect and mechanism of 9D11-Tat were investigated in cell and mouse models mimicking chronic HBV infection.

Results: Our results demonstrated that the recombinant 9D11-Tat antibody could efficiently internalize into living cells and significantly suppress viral transcription, replication, and protein production both in vitro and in vivo. Further analyses suggested the internalized 9D11-Tat antibody could greatly reduce intracellular HBx via Fc binding receptor TRIM21-mediated protein degradation. This process simultaneously stimulated the activations of NF-κB, AP-1, and IFN-β, which promoted an antiviral state of the host cell.

Conclusion: In summary, our study offers a new approach to target intracellular pathogenesis-related protein by engineered cell-penetrating mAb expanding their potential for therapeutic applications. Moreover, the 9D11-Tat antibody may provide a novel therapeutic agent against human chronic HBV infection.

Effects of antiviral therapy in patients with chronic hepatitis B and cirrhosis

Hepatitis B virus (HBV) infection is the major cause of cirrhosis worldwide. The ultimate goal of current antiviral treatments for chronic hepatitis B (nucleos(t)ide analogs and interferon-α) is to prevent the development of end-stage liver diseases. Areas covered: We present a review of the current literature on antiviral therapy in patients with chronic hepatitis B and cirrhosis. Medline search was performed to identify relevant literature from 1993 through January of 2017. Expert commentary: One randomized controlled trial and a number of observational studies have shown that nucleos(t)ide analogs can decrease the incidence of hepatocellular carcinoma (HCC) in chronic hepatitis B patients with advanced fibrosis. Data from clinical trials of entecavir and tenofovir have shown that histological improvement and regression of fibrosis can be achieved in the majority of patients with chronic hepatitis B by successful viral suppression. Entecavir and tenofovir are the preferred antiviral agents for treatment of chronic hepatitis B in patients with cirrhosis due to their high antiviral potency and high genetic barrier to resistance. Pegylated interferon-α is another therapeutic option for chronic hepatitis B patients with well-compensated cirrhosis. However, interferon therapy is contraindicated in patients with decompensated cirrhosis, and evidence for reduced HCC is currently insufficient.

Tenofovir alafenamide as compared to tenofovir disoproxil fumarate in the management of chronic hepatitis B with recent trends in patient demographics

Tenofovir alafenamide (TAF) has recently been approved for chronic hepatitis B (CHB). It is more stable than tenofovir disoproxil fumarate (TDF) in the plasma and can provide similar efficacy with lower circulating concentration in patients with hepatitis B virus (HBV) infection. Areas covered: This synopsis will review the current anti-HBV standard practice and the changing epidemiology of CHB, specifically the controversies surrounding the renal and bone safety associated with TDF use in the context of an aging CHB population. We will review data from phase 3 registration trials, which demonstrated TAF was not inferior to TDF in antiviral efficacy for both HBeAg-positive and HBeAg-negative patients, while associated with less reduction in the estimated glomerular filtration rate and bone mineral density. Expert commentary: Current data supports the use of TAF as one of the first-line antiviral agents for general CHB patients without hepatic decompensation. However, more real-world data with long-term observation are needed to better define the role of TAF among other oral regimens. Additional studies are also needed to evaluate the efficacy and safety of TAF in special populations such as those with impaired hepatic function, existing impaired renal and/or bone function, and in pregnant women.

HDM2 Promotes NEDDylation of Hepatitis B Virus HBx To Enhance Its Stability and Function

Hepatitis B virus (HBV)-encoded X protein (HBx) plays a critical role in HBV-related hepatocarcinoma development. In this study, we demonstrate that HBx is specifically modified by NEDD8. We found that E3 ligase HDM2 promotes NEDDylation of HBx to enhance HBx stability by preventing its ubiquitination-mediated degradation. Consistently, analysis of 160 hepatocellular carcinoma patient specimens indicated that the amount of HDM2 protein correlates with HBx protein level. We identified that HBx K91 and K95 as the key HBx NEDDylation sites and observed that the NEDDylation-deficient HBx has shorter half-life. We generated Huh7 cell lines which ectopically express wild-type and NEDDylation-deficient HBx and found that NEDDylation-deficient HBx showed less chromatin localization and less DDB1 binding. Consistently, the expression of HBx-regulated genes (IL-8, MMP9, and YAP) and HBV transcription (the activity of HBV enhancer and the amount of pgRNA transcribed from cccDNA) were significantly higher in cells expressing wild-type (WT) HBx than that in cells expressing mutant HBx. In addition, HBx-expressing cells proliferated faster than control and mutant HBx-expressing cells. We also showed that the ability of WT HBx-expressing cells to form tumors in nude mice was significantly higher than that of mutant HBx-expressing cells. In conclusion, we revealed that E3 ligase HDM2 promotes NEDDylation of HBx to enhance HBx stability and chromatin localization, which in turn favors HBx-dependent transcriptional regulation, cell proliferation, and HBV-driven tumor growth.IMPORTANCE Hepatitis B virus (HBV) HBx protein plays a critical role in viral replication and hepatocarcinogenesis. However, the regulation of HBx stability is not well understood. We found that HBx is modified by NEDD8 and that the HDM2 E3 ligase promotes HBx NEDDylation to enhance HBx stability by inhibiting its ubiquitination. We provide a new evidence to show the positive correlation between HDM2 and HBx in clinical hepatocellular carcinoma (HCC) samples. We also identified the major NEDDylation sites on HBx. Our studies indicate that the defective NEDDylation of HBx negatively affects its ability to activate the transcription of downstream genes and promote cell proliferation and tumor growth in vivo Taken together, our findings reveal a novel posttranslational modification of HBx by HDM2 which regulates its stability, subcellular localization, and functions. These findings indicate that HDM2 is an important regulator on HBx and a potential diagnosis/therapeutic marker for HBV-associated HCC.

Tenofovir alafenamide for the treatment of chronic hepatitis B virus infection

INTRODUCTION

In April 2017 tenofovir alafenamide (TAF) was added to the list of first-line therapies recommended for chronic hepatitis B (CHB). TAF has pharmacology similar to tenofovir disoproxil fumarate (TDF) with higher cell delivery to the hepatocytes but less systemic exposure. Areas covered: We review here studies leading to TAF's approval and comparing it to TDF. In two major clinical trials, TAF was non-inferior to TDF in achieving HBV DNA levels below 29 IU/ml. TAF-treated patients had significantly smaller decreases in bone mineral density (BMD) at the hip and spine in both HBeAg-positive and HBeAg-negative patients, and smaller mean increases in serum creatinine, although the difference was only statistically significant in HBeAg-positive patients. Patients treated with TDF for 96 weeks and then switched to TAF had improvements in renal and BMD measures only 24 weeks after switching. Expert commentary: With clear evidence from major studies showing that TAF is safe, tolerable, and non-inferior to TDF, its recommendation as a first-line therapy is appropriate. Longer term follow up will be required to determine if the differences in adverse bone and kidney effects seen with TAF in comparison to TDF will be clinically relevant.

The Clinical Efficacy and Adverse Effects of Interferon Combined with Matrine in Chronic hepatitis B: A Systematic Review and Meta-Analysis

Currently, many studies have demonstrated certain beneficial effects of interferon (IFN) combined with matrine (Mat) for chronic hepatitis B (CHB) in China. However, the evidence from these randomized control trials is still controversial. Therefore, the aim of this meta-analysis was to explore the efficacy and safety of Mat combined with IFN for CHB. We performed a systematic search of seven databases to identify all randomized controlled trials that treated CHB with IFN or IFN plus Mat from their start date to September 30, 2015. The clinical efficacy and adverse effects were evaluated. Nine studies involving 1089 participants were included. Compared with IFN monotherapy, IFN 5 MU combined with Mat 150 mg augmented the hepatitis B e-antigen negative conversion rate after 3-month treatment [relative ratio (RR) = 1.41; 95% confidence interval (CI) (1.18, 1.69), p = 0.0002] and after 12-month treatment [RR = 1.96; 95% CI (1.21, 3.19), p = 0.006], hepatitis B virus DNA negative conversion rate after 3-month treatment [RR = 1.37; 95% CI (1.16, 1.62), p = 0.0002] and after 12-month treatment [RR = 1.96; 95% CI (1.21, 3.19), p = 0.006], hepatitis B virus e antibody (anti-HBe) conversion rate after 3-month treatment [RR = 1.47; 95% CI (1.19, 1.81), p = 0.0003], and AST level after 3-week treatment [weighted mean difference = -22; 95% CI (-40.41, -3.59), p = 0.02]. Furthermore, IFN 3 MU 3 months combined with Mat 150 mg after 2-month treatment reduced the risk of leucopenia and thrombocytopenia [RR = 0.55; 95% CI (0.36, 0.85), p = 0.007]. Unfortunately, all of the included trials were not in favor of hepatitis B surface antigen (HBsAg) negative conversion rate or influenza-like symptoms. Combination therapy with IFN plus Mat exhibited better clinical efficacy and fewer adverse effects than did IFN monotherapy in patients with CHB, except in the improvement of HBsAg negative conversion rate and influenza-like symptoms. Given the poor methodological quality of the evidence currently available, future high-quality, three-blinded randomized control trials are necessary to confirm these results. Copyright © 2017 John Wiley & Sons, Ltd.

Cyclosporin derivatives inhibit hepatitis B virus entry without interfering with NTCP transporter activity

BACKGROUND & AIMS

The sodium taurocholate co-transporting polypeptide (NTCP) is the main target of most hepatitis B virus (HBV) specific entry inhibitors. Unfortunately, these agents also block NTCP transport of bile acids into hepatocytes, and thus have the potential to cause adverse effects. We aimed to identify small molecules that inhibit HBV entry while maintaining NTCP transporter function.

METHODS

We characterized a series of cyclosporine (CsA) derivatives for their anti-HBV activity and NTCP binding specificity using HepG2 cells overexpressing NTCP and primary human hepatocytes. The four most potent derivatives were tested for their capacity to prevent HBV entry, but maintain NTCP transporter function. Their antiviral activity against different HBV genotypes was analysed.

RESULTS

We identified several CsA derivatives that inhibited HBV infection with a sub-micromolar IC50. Among them, SCY446 and SCY450 showed low activity against calcineurin (CN) and cyclophilins (CyPs), two major CsA cellular targets. This suggested that instead, these compounds interacted directly with NTCP to inhibit viral attachment to host cells, and have no immunosuppressive function. Importantly, we found that SCY450 and SCY995 did not impair the NTCP-dependent uptake of bile acids, and inhibited multiple HBV genotypes including a clinically relevant nucleoside analog-resistant HBV isolate.

CONCLUSIONS

This is the first example of small molecule selective inhibition of HBV entry with no decrease in NTCP transporter activity. It suggests that the anti-HBV activity can be functionally separated from bile acid transport. These broadly active anti-HBV molecules are potential candidates for developing new drugs with fewer adverse effects.

LAY SUMMARY

In this study, we identified new compounds that selectively inhibited hepatitis B virus (HBV) entry, and did not impair bile acid uptake. Our evidence offers a new strategy for developing anti-HBV drugs with fewer side effects.

Virological Response to Tenofovir Disoproxil Fumarate in HIV-Positive Patients with Lamivudine-Resistant Hepatitis B Virus Coinfection in an Area Hyperendemic for Hepatitis B Virus Infection

Background

Sequential addition of tenofovir disoproxil fumarate (TDF) is often needed for patients coinfected with HIV and hepatitis B virus (HBV) who develop HBV resistance to lamivudine after combination antiretroviral therapy (cART) containing only lamivudine for HBV. We aimed to assess the virological response of HBV to add-on TDF in patients coinfected with lamivudine-resistant HBV.

Methods

Between November 2010 and December 2014, 33 HIV/HBV-coinfected patients with lamivudine-resistant HBV and 56 with lamivudine-susceptible HBV were prospectively included. TDF plus lamivudine was used to substitute zidovudine or abacavir plus lamivudine contained in cART in patients with lamivudine-resistant HBV infection, while patients with lamivudine-susceptible HBV infection received TDF plus lamivudine as backbone of cART. Serial determinations of plasma HBV DNA load, HBV serologic markers, and liver and renal functions were performed after initiation of TDF-containing cART.

Results

Of 89 patients included, 38.6% tested positive for HBV envelope antigen (HBeAg) at baseline. The plasma HBV DNA level at enrollment of lamivudine-resistant and lamivudine-susceptible group were 6.1 ± 2.2 log₁₀ and 6.0 ± 2.2 log₁₀ copies/mL, respectively (p = 0.895). The cumulative percentage of HBV viral suppression in lamivudine-resistant and lamivudine-susceptible group was 81.8% and 91.1% at 48 weeks, respectively (p = 0.317), which increased to 86.7% and 96.2% at 96 weeks, respectively (p = 0.185). At 48 weeks, 11 patients testing HBeAg-positive at baseline failed to achieve viral suppression. In multivariate analysis, the only factor associated with failure to achieve viral suppression at 48 weeks was higher HBV DNA load at baseline (odds ratio, per 1-log₁₀ copies/mL increase, 1.861; 95% CI, 1.204–2.878). At 48 weeks, HBeAg seroconversion was observed in 5 patients (1 in the lamivudine-resistant group and 4 in the lamivudine-susceptible group; p = 0.166). During the study period, HBsAg levels decreased over time, regardless of lamivudine resistance. Loss of HBsAg was observed in 3 (3.4%) patients in the lamivudine-susceptible group.

Conclusions

Add-on TDF-containing cART in patients coinfected with lamivudine-resistant HBV achieved a similar rate of HBV viral suppression compared to TDF-containing cART as initial regimen in patients coinfected with lamivudine-susceptible HBV. A higher baseline HBV DNA load and HBeAg positivity were associated with failure to achieve HBV viral suppression.

Identification of UQCRB as an oxymatrine recognizing protein using a T7 phage display screen

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora flavescens Aiton (Radix Sophorae Flavescentis, Kushen) is used in traditional Chinese medicine to treat chronic hepatitis B (CHB), and has the ability to clear heat and dampness from the body. Oxymatrine is one of the major bioactive compounds extracted from Sophora flavescens Aiton and constitutes more than 90% of the oxymatrine injection commonly used for CHB treatment in clinics in China.

AIM OF THE STUDY

We aim to analyze the protein binding target of oxymatrine in treating CHB by screening a T7 phage display cDNA library of human CHB and examine the biochemistry of protein-ligand binding between oxymatrine and its ligands.

MATERIALS AND METHODS

A T7 phage cDNA library of human CHB was biopanned by affinity selection using oxymatrine as bait. The interaction of oxymatrine with its candidate binding protein was investigated by affinity assay, molecular docking, Isothermal Titration Calorimetry (ITC) and Surface Plasmon Resonance (SPR).

RESULTS

A library of potential oxymatrine binding peptides was generated. Ubiquinol-cytochrome c reductase binding protein (UQCRB) was one of the candidate binding proteins of oxymatrine. UQCRB-displaying T7 phage binding numbers in the oxymatrine group were significantly higher than that in the control group, biotin group, and matrine group (p<0.05 or p<0.01). Three-dimensional structure modeling of the UQCRB with oxymatrine showed that their binding interfaces matched and oxymatrine inserted into a deeper pocket of UQCRB, which mainly involved amino acid residues Tyr21, Arg33, Tyr83, Glu84, Asp86, Pro88, and Glu91. The binding affinity constant (Kb) from SPR was 4.2mM. The Kb from ITC experiment was 3.9mM and stoichiometry was fixed as 1, which fit very well with the result of SPR. The binding of oxymatrine to UQCRB was driven by strong enthalpy forces such as hydrogen bonds and polar interactions as the heat released was about 157kcal/mol and ΔG was less than zero.

CONCLUSIONS

In this study, using the T7 phage display system, we have identified UQCRB as a direct binding protein of oxymatrine. Furthermore, the specificity and molecular interaction of oxymatrine with UQCRB were also determined. The binding of UQCRB to oxymatrine suggests that UQCRB is a potential target of oxymatrine in treating CHB. These results provide new understanding into the mechanism of oxymatrine and insights into the strategy on the treatment of CHB.

Serum Wisteria floribunda agglutinin-positive Mac-2-binding protein for patients with chronic hepatitis B and C: a comparative study

We compared Wisteria floribunda agglutinin-positive Mac-2-binding protein (WFA⁺ -M2BP) levels between patients with chronic hepatitis B (n=249) and chronic hepatitis C (n=386) based on the degree of liver fibrosis. We examined WFA⁺ -M2BP levels in patients with F4 (cirrhosis), F3 or more (advanced fibrosis) and F2 or more (significant fibrosis) in the two groups. We further examined the relationship between five fibrosis markers and the degree of fibrosis. The WFA⁺ -M2BP values ranged from 0.25 cut-off index (COI) to 12.9 COI in patients with hepatitis B and 0.34-20.0 COI in patients with hepatitis C (P<.0001). The median WFA⁺ -M2BP values in F4 in the two groups were 2.83 COI in patients with hepatitis B and 5.03 COI in patients with hepatitis C (P=.0046). The median WFA⁺ -M2BP values in F3 or more in the two groups were 1.79 COI in patients with hepatitis B and 3.79 COI in patients with hepatitis C (P<.0001). The median WFA⁺ -M2BP values in F2 or more in the two groups were 1.49 COI in the hepatitis B cohort and 3.19 COI in the hepatitis C group (P<.0001). Among five liver fibrosis markers, WFA⁺ -M2BP had the highest correlation coefficient (r_s =.629) in terms of correlation with the degree of fibrosis in the patients with hepatitis C and had the second highest r_s value (.415) in the hepatitis B group. Although WFA⁺ -M2BP could be a useful indicator of liver fibrosis, WFA⁺ -M2BP levels in the two groups significantly differed even in the same degree of fibrosis. Individual cut-off values in each aetiology for the degree of fibrosis should be determined.