Two-year treatment outcome of chronic hepatitis B infection treated with besifovir vs. entecavir: results from a multicentre study

Efficacy comparison of high-genetic barrier nucleos(t)ide analogues in treatment-naïve chronic hepatitis B patients: a network meta-analysis

BACKGROUND/AIMS

Four high-genetic barrier nucleos(t)ide analogues (NAs) for chronic hepatitis B (CHB), namely entecavir (ETV), tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF), and besifovir dipivoxil maleate (BSV), have been established. The aim of this study is to investigate the efficacy of four high-genetic barrier NAs using a network meta-analysis of randomized trials and propensity score-matched cohorts.

METHODS

Systematic search was performed using PubMed, Cochrane library, and EMBASE and included randomized controlled trials and cohort studies that used propensity score matching. Studies on treatment-naïve CHB patients treated with ETV, TDF, TAF, or BSV were included. Outcomes included alanine aminotransferase normalization and hepatitis B e antigen seroclearance at week 48 and undetectable hepatitis B virus DNA at weeks 48 and 96. Network meta-analysis was performed to synthesize the results.

RESULTS

In total, 15,000 patients from 16 studies were included. In terms of 48- and 96-week virologic response (VR), TDF outperformed ETV with statistical significance (48 weeks: odds ratio [OR], 1.38; p < 0.001; 96 weeks: OR, 1.57; p = 0.004). ETV was ranked first for 48-week biochemical response (BR) and outperformed TDF (OR, 0.76; p = 0.028). In the sensitivity analyses, 48-week VR from randomized-controlled trials were compiled, and the same trend toward the superiority of TDF over ETV was found (OR, 1.51; p = 0.030).

CONCLUSION

Four high-genetic barrier NAs were compared, and TDF was more likely to achieve a VR after 48 weeks, while ETV provided a superior BR after 48 weeks.

Noninferiority Outcomes of Besifovir Compared to Tenofovir Alafenamide in Treatment-Naïve Patients with Chronic Hepatitis B

Background/Aims

: Besifovir dipivoxil maleate (BSV) and tenofovir alafenamide fumarate (TAF) have been recently approved in Korea as the initial antiviral agents for chronic hepatitis B (CHB). However, the real-world outcome data for these drugs remain limited. Therefore, we conducted a noninferiority analysis using real-world data to compare the clinical outcomes of the two nucleotide analogs in treatment-naïve patients with CHB.

Methods

: We retrospectively investigated a cohort of patients with CHB who received BSV or TAF as first-line antiviral agents. The endpoints were virological response (VR) and liver-related clinical outcomes.

Results

: A total of 537 patients, consisting of 202 and 335 patients administered BSV and TAF, respectively, were followed up for 42 months. No significant difference was observed between the VRs of the patients from the two groups. The rates of biochemical response, virologic breakthrough, and incidence rates of hepatocellular carcinoma did not differ between the groups. However, the hepatitis B e antigen seroclearance rate was higher and the renal function declined less in the BSV group. Multivariable analysis indicated older age, alcohol abuse, cirrhosis and ascites, and lower serum HBV DNA level to be independently associated with increased hepatocellular carcinoma risk. The 1:1 propensity score-matched analysis with 400 patients showed VR rates of 85.0% and 88.7% in the BSV and TAF group patients, respectively, at 2 years. The absolute value of the 95% confidence interval for the difference (-0.04 to 0.12) satisfied the a priori limit of a noninferiority of 0.15.

Conclusions

: BSV is noninferior to TAF in terms of VR, and their clinical outcomes are comparable to CHB.

Reduced Risk of Hepatocellular Carcinoma in Patients with Chronic Hepatitis B Receiving Long-Term Besifovir Therapy

No information is available regarding the influence of besifovir (BSV), a new nucleotide analogue, on the occurrence of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B (CHB). This study evaluated the reduced risk of HCC in patients undergoing BSV treatment. A total of 188 patients with CHB were treated with BSV for up to 8 years. We prospectively assessed the incidence of HCC compared with the risk from prediction models. During the follow-up, 5 patients developed HCC: 1 of 139 patients with non-cirrhotic CHB, and 4 of 49 patients with liver cirrhosis. We compared the HCC incidence in non-cirrhotic and cirrhotic patients with the predicted number derived from the REACH-B (risk estimation for HCC in CHB) model and GAG-HCC (guide with age, gender, HBV DNA, core promotor mutation, and cirrhosis) model, respectively. The standardized incidence ratio (SIR) was 0.128 (p = 0.039) at 7 years in non-cirrhotic CHB patients, and the SIR was 0.371 (p = 0.047) at 7.5 years in cirrhotic patients, suggesting a significantly decreased HCC incidence in both groups. HCC prediction was available for BSV-treated patients using existing models. In conclusion, BSV decreased the risk of HCC in patients with CHB, and prediction models were applicable. Clinical trial registry website and trial number: ClinicalTrials.gov no: NCT01937806.

Hepatitis B Virus Epsilon (ε) RNA Element: Dynamic Regulator of Viral Replication and Attractive Therapeutic Target

Hepatitis B virus (HBV) chronically infects millions of people worldwide, which underscores the importance of discovering and designing novel anti-HBV therapeutics to complement current treatment strategies. An underexploited but attractive therapeutic target is ε, a cis-acting regulatory stem-loop RNA situated within the HBV pregenomic RNA (pgRNA). The binding of ε to the viral polymerase protein (P) is pivotal, as it triggers the packaging of pgRNA and P, as well as the reverse transcription of the viral genome. Consequently, small molecules capable of disrupting this interaction hold the potential to inhibit the early stages of HBV replication. The rational design of such ligands necessitates high-resolution structural information for the ε-P complex or its individual components. While these data are currently unavailable for P, our recent structural elucidation of ε through solution nuclear magnetic resonance spectroscopy marks a significant advancement in this area. In this review, we provide a brief overview of HBV replication and some of the therapeutic strategies to combat chronic HBV infection. These descriptions are intended to contextualize our recent experimental efforts to characterize ε and identify ε-targeting ligands, with the ultimate goal of developing novel anti-HBV therapeutics.

Besifovir therapy improves hepatic histology and reduces covalently closed circular DNA in chronic hepatitis B patients

BACKGROUND AND AIM

Besifovir dipivoxil maleate (BSV) was reported to have comparable antiviral efficacy and superior renal and bone safety to tenofovir disoproxil fumarate (TDF) in chronic hepatitis B (CHB) patients. The present study aims to evaluate changes of liver histology and intrahepatic covalently closed circular DNA (cccDNA) levels by BSV treatment in comparison with TDF therapy.

METHODS

This is a subset study of the phase 3 trial comparing BSV with TDF. Among them, only CHB patients willing to participate in a histologic evaluation study were enrolled. Liver histologic examination and intrahepatic cccDNA quantification were performed.

RESULTS

A total of 46 CHB patients received liver biopsies (BSV, n = 29; TDF, n = 17). After 48 weeks of treatment, virological response rate was comparable between the groups (P = 0.707). Follow-up liver biopsies showed that necroinflammation was significantly improved in the both groups. However, the histological response rate defined as the proportion of subjects whose modified histologic activity index score decreased by ≥ 2 without deterioration in fibrosis was higher in the BSV group than in the TDF group (77.8% vs 36.4%, P = 0.048). The proportion of subjects with Ishak fibrosis score 3 or more decreased from 77.7% to 55.5% in the BSV and that decreased from 72.7% to 45.4% in the TDF group. The intrahepatic cccDNA significantly decreased from baseline after 48 weeks of BSV or TDF treatment (P < 0.001) without intergroup differences (P = 0.349).

CONCLUSIONS

The BSV therapy improves hepatic histology and decreases intrahepatic cccDNA in CHB patients.

Identification and Characterization of Besifovir-Resistant Hepatitis B Virus Isolated from a Chronic Hepatitis B Patient

Hepatitis B virus (HBV) is known to cause severe liver diseases such as acute or chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Chronic hepatitis B (CHB) infection is a major health problem with nearly 300 million individuals infected worldwide. Currently, nucleos(t)ide analogs (NAs) and interferon alpha are clinically approved treatments for HBV infection. NAs are potent antiviral agents that bind to HBV polymerase and block viral reverse transcription and replication. Besifovir dipivoxil maleate (BSV) is a newly developed NA against HBV in the form of acyclic nucleotide phosphonate that is available for oral administration similar to adefovir and tenofovir. Until now, resistance to BSV treatment has not been reported. In this study, we found a CHB patient who showed viral breakthrough after long-term treatment with BSV. The isolated HBV DNA from patient’s serum were cloned into the replication-competent HBV 1.2 mer and the sequence of reverse transcriptase (RT) domain of HBV polymerase were analyzed. We also examined the drug susceptibility of generated clones in vitro. Several mutations were identified in HBV RT domain. A particular mutant harboring ten RT mutations showed resistance to BSV treatment in vitro. The ten mutations include rtV23I (I), rtH55R (R), rtY124H (H), rtD134E (E), rtN139K (K), rtL180M (M), rtM204V (V), rtQ267L (L), rtL269I (I) and rtL336M (M). To further identify the responsible mutations for BSV resistance, we performed in vitro drug susceptibility assay on several artificial clones. As a result, our study revealed that rtL180M (M) and rtM204V (V) mutations, already known as lamivudine-resistant mutations, confer resistance to BSV in the CHB patient.

Besifovir dipivoxil maleate: a novel antiviral agent with low toxicity and high genetic barriers for chronic hepatitis B

INTRODUCTION

Chronic hepatitis B is an important public health concern. Introduction of oral nucleos(t)ide analogs (NAs), inhibitors of hepatitis B virus (HBV) polymerase, was a milestone that lowered the high viral loads associated with an increased risk of liver-related complications.

AREAS COVERED

Although the currently available NAs are effective in suppressing viral replication, anti-HBV treatment in principle requires lifelong drug administration, and some patients have limitations such as the incidence of liver cancer and the likelihood of toxicities following long-term treatment despite viral suppression. Besifovir dipivoxil maleate (BSV), an oral nucleotide analog, is a prodrug that is metabolized to its active form. It has consistent and well-characterized pharmacokinetics in animals and human. In clinical studies, BSV exhibits significant and potent viral suppression of HBV replication with maintenance of antiviral efficacy for over 192 weeks without resistance, or renal and bone toxicities. Herein, the authors discuss the data of BSV and provide the reader with their expert opinion.

EXPERT OPINION

BSV is a newly developed antiviral agent against HBV. This new agent has strong antiviral activity with low toxicity and a high barrier to resistance. Because there is concern that patients treated with a high dose of BSV require carnitine supplementation, BSV with carnitine supplementation is recommended during antiviral therapy.

Continuing besifovir dipivoxil maleate versus switching from tenofovir disoproxil fumarate for treatment of chronic hepatitis B: Results of 192-week phase 3 trial

Background/Aims

Besifovir dipivoxil maleate (BSV), an acyclic nucleotide phosphonate, shows potent antiviral activity against hepatitis B virus. Our previous 48-week trial revealed that BSV has comparable antiviral efficacy to tenofovir disoproxil fumarate (TDF) and better safety profiles in terms of improved renal and bone safety. This extension study evaluated the prolonged efficacy and safety of BSV in treatment-naive chronic hepatitis B patients.

Methods

Patients continued to participate in an open-label BSV study after an initial 48-week double-blind comparison of BSV and TDF treatment. The antiviral efficacy and drug safety was evaluated up to 192 weeks in two groups: patients continuing BSV treatment (BSV-BSV) and patients switching from TDF to BSV after 48 weeks (TDF-BSV).

Results

Among 197 patients receiving randomized treatments, 170 (86%) entered the open-label phase and 152 (77%) entered the 192-week extension study. Virological response rates over 192 weeks were 92.50% and 93.06% in the BSV-BSV and TDF-BSV groups, respectively (P=0.90). Hepatitis B envelop antigen seroconversion and alanine aminotransferase normalization rates were similar between the groups (P=0.75 and P=0.36, respectively). There were no drug-resistant mutations to BSV. Bone mineral density and renal function were well preserved in the BSV-BSV group, whereas these initially worsened then recovered after switching therapy in the TDF-BSV group.

Conclusions

BSV maintained potent antiviral efficacy after 192 weeks and showed no evidence of drug resistance. BSV was safe, well tolerated, and effective in patients who switched from TDF to BSV. Trial Registration Number: NCT01937806 (date: 10 Sep 2013).

Overview of Biologically Active Nucleoside Phosphonates

The use of the phosphonate motif featuring a carbon-phosphorous bond as bioisosteric replacement of the labile P–O bond is widely recognized as an attractive structural concept in different areas of medicinal chemistry, since it addresses the very fundamental principles of enzymatic stability and minimized metabolic activation. This review discusses the most influential successes in drug design with special emphasis on nucleoside phosphonates and their prodrugs as antiviral and cancer treatment agents. A description of structurally related analogs able to interfere with the transmission of other infectious diseases caused by pathogens like bacteria and parasites will then follow. Finally, molecules acting as agonists/antagonists of P2X and P2Y receptors along with nucleotidase inhibitors will also be covered. This review aims to guide readers through the fundamentals of nucleoside phosphonate therapeutics in order to inspire the future design of molecules to target infections that are refractory to currently available therapeutic options.

Besifovir Dipivoxil Maleate 144-Week Treatment of Chronic Hepatitis B: An Open-Label Extensional Study of a Phase 3 Trial

INTRODUCTION

Chronic hepatitis B (CHB) remains a major worldwide public health concern. Besifovir dipivoxil maleate (BSV) is a new promising treatment for CHB. However, long-term efficacy and safety have not yet been evaluated. Therefore, the goal of the study is to determine the antiviral efficacy and safety of BSV treatment over a 144-week duration (BSV-BSV) in comparison with those of a sequential treatment with tenofovir disoproxil fumarate (TDF) followed by a 96-week duration BSV administration (TDF-BSV).

METHODS

After 48 weeks of a double-blind comparison between BSV and TDF treatments, patients continued the open-label BSV study. We evaluated antiviral efficacy and drug safety up to 144 weeks for BSV-BSV and TDF-BSV groups. The primary endpoint was a virological response (hepatitis B virus DNA < 69 IU/mL).

RESULTS

Among the 197 patients enrolled, 170 and 158 patients entered the second-year and third-year open-label phase extensional study, respectively, whereas 153 patients completed the 144-week follow-up. The virological response rate over the 144-week period was 87.7% and 92.1% in BSV-BSV and TDF-BSV groups, respectively (P = 0.36). The rates of ALT normalization and HBeAg seroconversion were similar between the groups. No drug-resistant mutations to BSV were noted. Bone mineral density and renal function were well preserved in the BSV-BSV group and were significantly improved after switching therapy in TDF-BSV patients.

DISCUSSION

This extensional study of a phase 3 trial (NCT01937806) suggests that BSV treatment is efficacious and safe for long-term use in treatment-naïve and TDF-experienced patients with CHB.

HBV replication inhibitors

Chronic Hepatitis B Virus infections afflict >250 million people and kill nearly 1 million annually. Current non-curative therapies are dominated by nucleos(t)ide analogs (NAs) that profoundly but incompletely suppress DNA synthesis by the viral reverse transcriptase. Residual HBV replication during NA therapy contributes to maintenance of the critical nuclear reservoir of the HBV genome, the covalently-closed circular DNA, and to ongoing infection of naive cells. Identification of next-generation NAs with improved efficacy and safety profiles, often through novel prodrug approaches, is the primary thrust of ongoing efforts to improve HBV replication inhibitors. Inhibitors of the HBV ribonuclease H, the other viral enzymatic activity essential for viral genomic replication, are in preclinical development. The complexity of HBV's reverse transcription pathway offers many other potential targets. HBV's protein-priming of reverse transcription has been briefly explored as a potential target, as have the host chaperones necessary for function of the HBV reverse transcriptase. Improved inhibitors of HBV reverse transcription would reduce HBV's replication-dependent persistence mechanisms and are therefore expected to become a backbone of future curative combination anti-HBV therapies.

Influence of Besifovir Dipivoxil Maleate Combined with L-Carnitine on Hepatic Steatosis in Patients with Chronic Hepatitis B

BACKGROUND

Besifovir dipivoxil maleate (BSV) with L-carnitine is the first-line antiviral agent for chronic hepatitis B (CHB) infection. We investigated whether BSV combined with L-carnitine improves hepatic steatosis (HS).

METHODS

Treatment-naïve patients with CHB who were initiated on antiviral therapy (AVT) were enrolled. The magnitude of HS was assessed using hepatic steatosis index (HSI), and HS improvement was defined as a ≥ 10% reduction in the HSI score from the baseline.

RESULTS

The mean age of the study patients was 56 years with a male predominance (n = 178, 64.7%). The mean body mass index (BMI), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and platelet count were 23.5 kg/m², 49.6 IU/L, 49.0 IU/L, and 191.3 × 10⁹/L, respectively. The mean HSI and fibrosis (FIB)-4 index were 32.6 and 0.5, respectively. After 6 months of AVT, platelet count (mean, 191.3→167.0 × 10⁹/L), fasting glucose (mean, 113.1→105.9 mg/dL), AST (mean, 49.6→28.0 IU/L), ALT (mean, 49.0→33.9 IU/L), and total cholesterol (mean, 170.0→162.1 mg/dL) levels significantly decreased (all P < 0.05). In the BSV group, AST (mean, 95.2→30.2 IU/L) and ALT (mean, 81.1→31.1 IU/L) levels significantly reduced (all P < 0.05), whereas HSI and FIB-4 index were maintained (all P > 0.05). In the univariate analysis, age, BMI, diabetes, cirrhosis, fasting glucose level, and ALT were significantly associated with HS improvement (all P < 0.05).

CONCLUSION

BSV with L-carnitine did not show any improvement of HS in patients with CHB. Further prospective randomized controlled studies are needed to validate the potential beneficial effects of BSV with L-carnitine in CHB infection.

Adverse events of nucleos(t)ide analogues for chronic hepatitis B: a systematic review

Nucleos(t)ide analogues (NAs) are the main drug category used in chronic hepatitis B (CHB) treatment. Despite the fact that NAs have a favourable safety profile, undesired adverse events (AEs) may occur during the treatment of CHB. Given the eminent number of patients currently receiving NAs, even a small risk of any of these toxicities can represent a major medical issue. The main objective of this review was to analyse information available on AEs associated with the use of NAs in published studies. We choose the following MesH terms for this systematic review: chronic hepatitis B, side effects and treatment. All articles published from 1 January 1990 up to 19 February 2018 in MEDLINE of PubMed, EMBASE, the Cochrane Library and LILACS databases were searched. A total of 120 articles were selected for analysis, comprising 6419 patients treated with lamivudine (LAM), 5947 with entecavir (ETV), 3566 with tenofovir disoproxil fumarate (TDF), 3096 with telbivudine (LdT), 1178 with adefovir dipivoxil (ADV) and 876 with tenofovir alafenamide (TAF). The most common AEs in all NAs assessed were abdominal pain/discomfort, nasopharyngitis/upper respiratory tract infections, fatigue, and headache. TAF displays the highest density of AEs per patient treated among NAs (1.14 AE/treated patient). In conclusion, treatment of CHB with NAs is safe, with a low incidence of AEs. Despite the general understanding TAF being safer than TDF, the number of patients treated with TAF still is too small in comparison to other NAs to consolidate an accurate safety profile. PROSPERO Registration No. CRD42018086471.

Efficacy and Safety of Besifovir Dipivoxil Maleate Compared With Tenofovir Disoproxil Fumarate in Treatment of Chronic Hepatitis B Virus Infection

BACKGROUND & AIMS

Besifovir dipivoxil maleate (BSV) has activity against hepatitis B virus (HBV). We performed a phase 3 study to compare the antiviral efficacy and safety of BSV vs tenofovir disoproxil fumarate (TDF) in patients with chronic HBV infection in Korea.

METHODS

We conducted a double-blind, non-inferiority trial of 197 patients with chronic HBV infection at 22 sites in South Korea, from November 2013 through February 2016. Patients were randomly assigned to groups given BSV (150 mg, n = 99) or TDF (300 mg, n = 98) for 48 weeks. We evaluated virologic responses to therapy (HBV DNA <69 IU/mL or 400 copies/ml), bone mineral density (BMD), and renal outcomes for safety analysis. The main efficacy endpoint was the proportion of patients with a virologic response at week 48. After 48 weeks, TDF was switched to BSV (150 mg) for an additional 48 weeks.

RESULTS

After 48 weeks of treatment, 80.9% of patients given BSV and 84.9% of patients given TDF met the efficacy endpoint, indicating the non-inferiority of BSV to TDF. At week 96, 87.2% of patients in the BSV-BSV and 85.7% of patients in the TDF-BSV had a virologic response. At week 48, changes in hip and spine BMD differed significantly between the BSV and TDF groups, whereas the estimated glomerular filtration rate in the TDF group was significantly lower than that in the BSV group. However, at 96 weeks, there were no significant differences in BMD and estimated glomerular filtration rate between the BSV-BSV and TDF-BSV groups.

CONCLUSIONS

BSV has antiviral efficacy comparable to that of TDF after 48 weeks of treatment, with durable effects for 96 weeks. BSV has a better safety profile than TDF, in terms of bone and renal outcomes. ClinicalTrials.gov no: NCT01937806.

Longitudinal effects of Nucleos(t)ide analogue therapy in chronic hepatitis B patients and the utility of non-invasive fibrosis markers during treatment: A single-center experience for up to 17 years

BACKGROUND

Fibrosis regression has been associated with nucleoside analogue (NA) treatment in chronic hepatitis B (CHB) patients. Although non-invasive fibrosis markers have been evaluated in CHB, their utility for monitoring on-treatment histologic regression has not been evaluated.

AIMS

To characterize improvements in disease severity and the utility of non-invasive biomarkers in CHB NA treated patients.

METHODS

Histology, labs, AST-to-platelet ratio index, and Fibrosis-4 (Fib-4) from treatment-naïve CHB patients were evaluated at baseline and longitudinally. Relative change from baseline to various time points during treatment were evaluated. Correlative analysis of APRI and Fib-4 with histology was performed longitudinally.

RESULTS

80 CHB patients (84% male, median age 45 (IQR 32, 54)) with histology up to 17 years (median 6(IQR 3.9, 8.0)) years were studied. Median baseline Ishak fibrosis was 3 (IQR 2, 4), histologic activity index (HAI) inflammation was 9 (IQR 7, 11), and AUROC of fibrosis markers for detecting cirrhosis (Ishak ≥ 5) was >0.64. HAI improved at a rate of 54% during year 1 and 37% in year 2, both greater than in the remaining follow-up periods. Within the first year, fibrosis improved by 35%, greater than all other time periods. Non-invasive biomarkers began to correlate with histology beyond 4 years (APRI: 4-6 years: r = 0.33, p = 0.03; ≥6 years: r = 0.41, p = 0.009; Fib-4: ≥6 years: r = 0.35, p = 0.03).

CONCLUSION

Early dynamic changes in histology occur in CHB patients on NA followed by linear improvements. Non-invasive fibrosis biomarkers do not capture these dynamic changes and may demonstrate clinical utility beyond 4 years of treatment.

Current state-of-the-art pharmacotherapy for the management of hepatitis B infection

INTRODUCTION

Hepatitis B virus (HBV) infection remains a global challenge with several hundred million infected individuals. Disease activity can be controlled, and adverse outcomes prevented when treatment can be provided. Frequently life-long therapy is required instead of defined treatment periods such as with the case of Hepatitis C Virus (HCV) infection.

AREAS COVERED

In this review, the authors provide an overview of current start of the art therapy for HBV and indicate where variation from the current guidelines could be considered. Certain patients may be eligible for treatment with suboptimal therapies when their baseline viral load is low. Identifying ideal candidates for interferon therapy will result in good sustained responses for some patients.

EXPERT OPINION

The biggest challenge remains linking patients to care and therapy. Patients can nowadays be sufficiently treated before the disease advances to a more progressed phase. However, future therapies must be extremely safe and ideally limit the required treatment period. Given Hepatitis D Virus's dependence on HBV and being a disease with an unmet clinical need, HDV may be the best target group for the development of a functional cure for hepatitis B.

Development of Direct-acting Antiviral and Host-targeting Agents for Treatment of Hepatitis B Virus Infection

Hepatitis B virus (HBV) infection affects approximately 300 million people worldwide. Although antiviral therapies have improved the long-term outcomes, patients often require life-long treatment and there is no cure for HBV infection. New technologies can help us learn more about the pathogenesis of HBV infection and develop therapeutic agents to reduce its burden. We review recent advances in development of direct-acting antiviral and host-targeting agents, some of which have entered clinical trials. We also discuss strategies for unbiased high-throughput screens to identify compounds that inhibit HBV and for repurposing existing drugs.

The management of hepatitis B and hepatitis C in children

In the present paper, we review the increased disease burden of hepatitis B (HBV) and hepatitis C (HCV) infection that is recognized worldwide; especially in children when the most common mode of transmission is vertically from infected mothers. In children with HBV and HCV infection, spontaneous clearance of the virus in the first years of life is not common, in contrast with adults, but these patients often stay asymptomatic until early adulthood, when disease has progressed to chronic hepatitis with increased risk of cirrhosis and its complication, and hepatocellular carcinoma. Due to limited treatment options of HBV infection in the pediatric population, clinicians focus on primary prevention, by vaccinating all infants during their first days of life. Infants born to infected mothers, receive intravenous immunoglobulin on top of the vaccine, and thus preventing transmission in 95% of the infants. While for HCV infection, since there is no vaccine to prevent HCV disease, providers focus primarily on treatment. The treatment landscape of HCV infection in children rapidly evolves, away from interferon regimens, and towards direct-acting antiviral agents that have a safer and more efficacious drug profile. Currently, there are ongoing clinical trials investigating the efficacy and tolerance of direct-acting agents in children below 12 years of age.

Towards HBV curative therapies

Tremendous progress has been made over the last 2 decades to discover and develop approaches to control hepatitis B virus (HBV) infections and to prevent the development of hepatocellular carcinoma using various interferons and small molecules as antiviral agents. However, none of these agents have significant impact on eliminating HBV from infected cells. Currently the emphasis is on silencing or eliminating cccDNA, which could lead to a cure for HBV. Various approaches are being developed including the development of capsid effectors, CRISPR/Cas9, TALENS, siRNA, entry and secretion inhibitors, as well as immunological approaches. It is very likely that a combination of these modalities will need to be employed to successfully eliminate HBV or prevent virus rebound on discontinuation of therapy. In the next 5 years clinical data will emerge which will provide insight on the safety and feasibility of these approaches and if they can be applied to eradicate HBV infections globally. In this review, we summarize current treatments and we highlight and examine recent therapeutic strategies that are currently being evaluated at the preclinical and clinical stage.

Upcoming pharmacological developments in chronic hepatitis B: can we glimpse a cure on the horizon?

Background

Hepatitis B virus (HBV) chronic infection affects up to 240 million people in the world and it is a common cause of cirrhosis and hepatocellular carcinoma (HCC). HBV covalently closed circular DNA (cccDNA) plays an essential role in HBV persistence and replication. Current pharmacological treatment with nucleos(t)ide analogues (NA) may suppress HBV replication with little or no impact on cccDNA, hence lifelong treatment is required in the vast majority of patients. Clearances of intrahepatic cccDNA and/or HBsAg are critical endpoints for future antiviral therapy in chronic HBV. Recent promising developments targeting different molecular HBV life cycle steps are being pre-clinically tested or have moved forward in early clinical trials.

Methods

We review the current state of the art of these pharmacological developments, mainly focusing on efficacy and safety results, which are expected to lay the ground for future HBV eradication. An inclusive literature search on new treatments of HBV using the following electronic databases: Pubmed/MEDLINE, AMED, CINAHL and the Cochrane Central Register of Controlled Trials. Full-text manuscripts and abstracts published over the last 12 years, from 2005 to March 2011 were reviewed for relevance and reference lists were crosschecked for additional applicable studies regarding new HBV antiviral treatment.

Results

HBV entry inhibitors, HBV core inhibitors, HBV cccDNA transcripts RNA interference, HBV cell apoptosis inducers, HBV RNA, viral proteins and DNA knock down agents, HBV release inhibitors, anti-sense nucleosides, exogenous interferon stimulation, interferon response stimulation and HBV therapeutic vaccines were reviewed.

Conclusion

This review will provide readers with an updated vision of current and foreseeable therapeutic developments in chronic hepatitis B.

Pharmacokinetic evaluation of besifovir for the treatment of HBV infection

INTRODUCTION

Besifovir (LB80380) is a relatively new oral acyclic nucleotide phosphonate. We reviewed the pharmacokinetic characteristics of LB80380 and discussed its role in the treatment of chronic hepatitis B infection. Areas covered: LB80380 is a prodrug of LB80331 and LB80317. It is rapidly absorbed when taken orally. Escalating doses of besifovir produce linear increase of the plasma concentration. Doses above 60mg are effective for inhibiting HBV in human. Using 60mg as an example, the maximal concentration of LB80331 in plasma is 397 ng/mL. The time required to reach maximal concentration in plasma and elimination half-life are 2.0 and 3.0 h, respectively. Besifovir and its metabolites are mainly excreted via the kidneys. Its antiviral efficacy is non-inferior to ETV 0.5mg daily. It is generally safe in terms of renal and bone toxicity. The most common adverse event is carnitine depletion which affects almost all patients on besifovir requiring carnitine supplementation. Expert opinion: Besifovir demonstrated predictable pharmacokinetic characteristics in human subjects. Few clinical studies on besifovir have been conducted. More data are expected particularly for special populations. The adverse events upon long term exposure should be monitored. Large scale head-to-head trials comparing besifovir with existing NA, especially tenofovir alafenamide, should be conducted.

Novel therapies and potential therapeutic targets in the management of chronic hepatitis B

Chronic hepatitis B is a persistent and progressive inflammatory liver disease caused by infection with the hepatitis B virus (HBV). More than 240 million individuals are infected with HBV worldwide and hepatitis B accounts for an estimated 650 000 deaths annually. Approximately up to 30% of chronically infected patients will develop complications of HBV infection including, but not limited to, liver cirrhosis, end-stage liver disease, and hepatocellular carcinoma. Currently approved therapies have improved clinical outcomes, but have a considerable side-effect profile, elevated cost, and a finite course of treatment. This has led to a growing interest in research for new therapies. As the mechanisms for HBV replication are becoming better understood, new potential targets have been discovered, leading to the development of new therapies. In this article, we describe the promising therapies that are under evaluation, showing their mechanisms of action, effects, and stage of development.

Treatment of hepatitis B virus: an update

Chronic hepatitis B virus infection is a global health concern as it affects over 240 million people worldwide and an estimated 686,000 people die annually as a result of complications of the disease. With the development of newer antiviral drugs, viral suppression of HBV is achievable, however elimination of HBV from infected individuals (functional cure) remains an issue. Due to persistence of HBV DNA (cccDNA) in infected cells, chronically infected patients who discontinue therapy prior to HBsAg loss or seroconversion are likely to relapse. Several novel therapeutic strategies are being researched and studied in clinical trials. Here we review these novel strategies to achieve sustained cure or elimination of HBV. These strategies include the targeting of the host or viral factors required for viral persistence as well as therapeutic vaccines.

Inhibitor-Based Therapeutics for Treatment of Viral Hepatitis

Viral hepatitis remains a significant worldwide threat, in spite of the availability of several successful therapeutic and vaccination strategies. Complications associated with acute and chronic infections, such as liver failure, cirrhosis and hepatocellular carcinoma, are the cause of considerable morbidity and mortality. Given the significant burden on the healthcare system caused by viral hepatitis, it is essential that novel, more effective therapeutics be developed. The present review attempts to summarize the current treatments against viral hepatitis, and provides an outline for upcoming, promising new therapeutics. Development of novel therapeutics requires an understanding of the viral life cycles and viral effectors in molecular detail. As such, this review also discusses virally-encoded effectors, found to be essential for virus survival and replication in the host milieu, which may be utilized as potential candidates for development of alternative therapies in the future.

Viral hepatitis: Indian scenario

Viral hepatitis is a cause for major health care burden in India and is now equated as a threat comparable to the "big three" communicable diseases - HIV/AIDS, malaria and tuberculosis. Hepatitis A virus and Hepatitis E virus are predominantly enterically transmitted pathogens and are responsible to cause both sporadic infections and epidemics of acute viral hepatitis. Hepatitis B virus and Hepatitis C virus are predominantly spread via parenteral route and are notorious to cause chronic hepatitis which can lead to grave complications including cirrhosis of liver and hepatocellular carcinoma. Around 400 million people all over the world suffer from chronic hepatitis and the Asia-Pacific region constitutes the epicentre of this epidemic. The present article would aim to cover the basic virologic aspects of these viruses and highlight the present scenario of viral hepatitis in India.

Serum metabolomic signatures discriminate early liver inflammation and fibrosis stages in patients with chronic hepatitis B

Chronic HBV (CHB) infected patients with intermediate necroinflammation and fibrosis are recommended to receive antiviral treatment. However, other than liver biopsy, there is a lack of sensitive and specific objective method to determine the necroinflammation and fibrosis stages in CHB patients. This study aims to identify unique serum metabolomic profile associated with histological progression in CHB patients and to develop novel metabolite biomarker panels for early CHB detection and stratification. A comprehensive metabolomic profiling method was established to compare serum samples collected from health donor (n = 67), patients with mild (G < 2 and S < 2, CHB1, n = 52) or intermediate (G ≥ 2 or S ≥ 2, CHB2, n = 36) necroinflammation and fibrosis. Multivariate models were developed to differentiate CHB1 and CHB2 from controls. A set of CHB-associated biomarkers was identified, including lysophosphatidylcholines, phosphatidylcholines, phosphatidylinositol, phosphatidylserine, and bile acid metabolism products. Stratification of CHB1 and CHB2 patients by a simple logistic index, the PIPSindex, based on phosphatidylinositol (PI) and phosphatidylserine (PS), was achieved with an AUC of 0.961, which outperformed all currently available markers. A panel of serum metabolites that differentiate health control, CHB1 and CHB2 patients has been identified. The proposed metabolomic biosignature has the potential to be used as indicator for antiviral treatment for CHB management.

Review article: novel therapies for hepatitis B virus cure - advances and perspectives

BACKGROUND

Current anti-viral therapies, interferon and nucleos(t)ide analogues, have been proven to reduce the progression of chronic hepatitis B (CHB). However, covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) persists, resulting in viral relapse after the discontinuation of treatment.

AIM

To discuss and review novel therapies for chronic hepatitis B infection.

METHODS

Recent published studies which searched from PubMed were comprehensive reviewed. The key words include chronic hepatitis B, hepatitis B virus cure, covalently closed circular DNA, direct acting anti-virals and host targeting agents.

RESULTS

Several novel agents through viral and host targets approaches are under investigations towards functional cure of HBV. On the one hand, direct acting anti-virals targeting virus itself, such as HBV new polymerase inhibitor, entry inhibitor, engineered site-specific nucleases and RNA interference, could inhibit amplification of cccDNA as well as intrahepatic HBV infection and eliminate or silence cccDNA transcription. Inhibitors of HBV nucleocapsid assembly suppress capsid formation and prevent synthesis of HBV DNA. On the other hand, host targeting agents (HTA) include lymphotoxin-β receptor agonist, toll-like receptor agonist, immune checkpoint inhibitors and adenovirus-based therapeutic vaccine. Through enhancing innate and adaptive immune responses, these agents could induce noncytolytic destruction of cccDNA or attack HBV-infected hepatocytes.

CONCLUSION

With these promising approaches, we hope to reach global hepatitis B virus control in the middle of this century.

Hepatitis B: Working Towards a Cure

First-line oral therapies for hepatitis B are effective at viral suppression, and treatment can lead to biochemical improvement and histologic regression. Unfortunately, recommended endpoints of treatment such as HBeAg loss and seroconversion may not be durable, with high rates of seroreversion, requiring monitoring, and unfortunately, low rates of  HBsAg loss/seroconversion. Additionally, meeting these endpoints requires years or even indefinite administration, leading to concerns regarding cost, side effects, and high rates of nonadherence. This article will review defined endpoints of therapy and their durability, the risks of long-term therapy, and the evolving new therapies aimed at a viral cure.

Hepatitis B virus: new therapeutic perspectives

Current antiviral therapies have dramatically improved the long-term outcomes of patients with chronic hepatitis B virus (HBV) infection. Both interferon (IFN) and nucleos(t)ide analogue (NA) treatments have been shown to reduce the progression of liver disease in chronic hepatitis B (CHB) patients. However, persistent covalently closed circular DNA (cccDNA) can result in a viral relapse after discontinuation of antiviral treatment. On the basis of extensive research on the HBV lifecycle and virus-host interactions, several new agents focusing on viral and host targets are under development to cure HBV. New polymerase inhibitors, tenofovir alafenamide and besifovir provide effective and safer treatment for CHB patients. Agents targeting cccDNA, such as engineered site-specific nucleases and RNA interference therapeutics could eliminate cccDNA or silence cccDNA transcription. Inhibitors of HBV nucleocapsid assembly suppress capsid formation and prevent synthesis of HBV DNA. The HBV entry inhibitor, Myrcludex-B, has been shown to effectively inhibit amplification of cccDNA as well as the spread of intrahepatic infection. Agents targeting host factors that enhance innate and adaptive immune responses, including the lymphotoxin-β receptor agonist, toll-like receptor agonist, immune checkpoint inhibitors and adenovirus-based therapeutic vaccine, could play a critical role in the elimination of HBV-infected cells. With all of these promising approaches, we hope to reach the ultimate goal of a cure to HBV in the near future.

Hepatitis B virus reverse transcriptase - Target of current antiviral therapy and future drug development

Hepatitis B virus (HBV) infections rely on the proper functioning of the viral polymerase enzyme, a specialized reverse transcriptase (RT) with multiple activities. All currently approved antiviral drugs for the treatment of chronic HBV infection, except for interferon, target the RT and belong to the same chemical class - they are all nucleoside analogs. Viral DNA synthesis is carried out by the RT enzyme in several different steps, each with distinct RT conformational requirements. In principle, each stage may be targeted by distinct antiviral drugs. In particular, the HBV RT has the unique ability to initiate viral DNA synthesis using itself as a protein primer in a novel protein priming reaction. In order to help identify RT inhibitors and study their mechanisms of action, a number of experimental systems have been developed, each varying in its ability to dissect the protein priming stage and subsequent stages of viral DNA synthesis at the molecular level. Two of the most effective drugs to date, entecavir and tenofovir, can inhibit both the protein priming and the subsequent DNA elongation stages of HBV DNA synthesis. Interestingly, clevudine, a thymidine analog, can inhibit both protein priming and DNA elongation in a non-competitive manner and without being incorporated into the viral DNA. Thus, a nucleoside RT inhibitor (NRTI) can functionally mimic a non-NRTI (NNRTI) in its inhibition of the HBV RT. Therefore, novel NRTIs as well as NNRTIs may be developed to inhibit the DNA synthesis activity of the HBV RT. Furthermore, additional activities of the RT that are also essential to HBV replication, including specific recognition of the viral RNA and its packaging into viral nucleocapsids, may be exploited for antiviral development. To achieve a more potent inhibition of viral replication and ultimately cure chronic HBV infection, the next generation of anti-HBV therapies will likely need to include NRTIs, NNRTIs, and other agents that target the viral RT as well as other viral and host factors in various combinations. This article forms part of a symposium in Antiviral Research on "An unfinished story: from the discovery of the Australia antigen to the development of new curative therapies for hepatitis B."