Benefits and risks of nucleoside analog therapy for hepatitis B

Immunomodulatory and Antiviral Therapy Improved Functional Cure Rate in CHB Patients with High HBsAg Level Experienced NA

Background and Aims

A functional cure, or hepatitis B virus (HBV) surface antigen (HBsAg) loss, is difficult to achieve in patients with hepatitis B virus e antigen (HBeAg)-positive chronic hepatitis B. The HBV vaccine and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been reported to help reduce HBsAg levels and promote HBsAg loss. In this prospective randomized trial, we evaluated HBsAg loss in patients receiving pegylated interferon-α2b (PEGIFN-α2b) and tenofovir disoproxil fumarate (TDF), with and without GM-CSF and HBV vaccination.

Methods

A total of 287 patients with HBeAg positive chronic hepatitis B and seroconversion after nucleot(s)ide analog treatment were assigned randomly to three treatment groups for 48 weeks, TDF alone (control), PEGIFN-α2b + TDF, and PEGIFN-α2b + TDF + GM-CSF + HBV vaccine. The primary endpoints were the proportions of patients with HBsAg loss and seroconversion at 48 and 72 weeks.

Results

The cumulative HBsAg loss rates in the control, PEGIFN-α2b + TDF, and PEGIFN-α2b + TDF + GM-CSF + HBV vaccine groups at week 48 were 0.0%, 28.3%, and 41.1%, respectively. The cumulative HBsAg seroconversion rates in these groups at week 48 were 0.0%, 21.7%, and 33.9%, respectively. Multivariate regression analysis showed that GM-CSF use plus HBV vaccination was significantly associated with HBsAg loss (p=0.017) and seroconversion (p=0.030).

Conclusions

In patients with HBeAg-positive chronic hepatitis B and seroconversion after nucleot(s)ide analog treatment, immunomodulatory/antiviral treatment regimens effectively improved HBsAg loss, and the regimen including GM-CSF and HBV vaccination was most effective.

Chronic Hepatitis B Infection: New Approaches towards Cure

Chronic hepatitis B virus (HBV) infection leads to the development of cirrhosis and hepatocellular carcinoma. Lifelong treatment with nucleotides/nucleoside antiviral agents is effective at suppressing HBV replication, however, adherence to daily therapy can be challenging. This review discusses recent advances in the development of long-acting formulations for HBV treatment and prevention, which could potentially improve adherence. Promising new compounds that target distinct steps of the virus life cycle are summarized. In addition to treatments that suppress viral replication, curative strategies are focused on the elimination of covalently closed circular DNA and the inactivation of the integrated viral DNA from infected hepatocytes. We highlight promising long-acting antivirals and genome editing strategies for the elimination or deactivation of persistent viral DNA products in development.

Canocapavir Is a Novel Capsid Assembly Modulator Inducing a Conformational Change of the Linker Region of HBV Core Protein

Canocapavir is a novel antiviral agent with characteristics of core protein allosteric modulators (CpAMs) that is currently in a phase II clinical trial for treatment of hepatitis B virus (HBV) infection. Herein, we show that Canocapavir prevented the encapsidation of HBV pregenomic RNA and increased the accumulation of cytoplasmic empty capsids, presumably by targeting the hydrophobic pocket at the dimer-dimer interface of HBV core protein (HBc). Canocapavir treatment markedly reduced the egress of naked capsids, which could be reversed by Alix overexpression through a mechanism other than direct association of Alix with HBc. Moreover, Canocapavir interfered with the interaction between HBc and HBV large surface protein, resulting in diminished production of empty virions. Of particular note, Canocapavir induced a conformational change of capsids, with the C-terminus of HBc linker region fully exposed on the exterior of capsids. We posit that the allosteric effect may have great importance in the anti-HBV activity of Canocapavir, given the emerging virological significance of HBc linker region. In support of this notion, the mutation at HBc V124W typically recapitulated the conformational change of the empty capsid with aberrant cytoplasmic accumulation. Collectively, our results indicate Canocapavir as a mechanistically distinct type of CpAMs against HBV infection.

Safety profile, antiviral capacity, and liver protection of a nasal therapeutic vaccine in patients with chronic hepatitis B: Five-year-follow-up outcomes after the end of treatment

Introduction

There is a pressing need to develop novel drugs for treating patients with chronic hepatitis B (CHB), as commercially available antiviral drugs are endowed with safety and efficacy concerns.

Methods

A phase III clinical trial was conducted with a therapeutic vaccine containing two antigens of the hepatitis B virus (HBV; named NASVAC) in 78 patients with CHB expressing both HBV DNA and elevated levels of alanine aminotransferase (ALT) in the blood. Five years after the end of treatment (EOT), 60 NASVAC-recipient patients were enrolled in this long-term follow-up study to evaluate the safety, antiviral potential, and liver-protective capacity of NASVAC.

Results

NASVAC exhibited an excellent safety profile 5 years after EOT. The levels of HBV DNA in the sera were reduced in 55 of the 60 patients, and 45 of them were negative for HBV DNA in the sera. ALT levels were also normalized in 40 of the 60 patients 5 years after EOT. None of the patients receiving NASVAC developed liver cirrhosis or cancer.

Discussion

The present study is the first to exhibit long-term follow-up data of a finite immune therapy for CHB that is safe and endowed with potent antiviral and liver-protecting capacities.

Antiviral supramolecular polymeric hydrogels by self-assembly of tenofovir-bearing peptide amphiphiles

The development of long-acting antiviral therapeutic delivery systems is crucial to improve the current treatment and prevention of HIV and chronic HBV. We report here on the conjugation of tenofovir (TFV), an FDA approved nucleotide reverse transcriptase inhibitor (NRTI), to rationally designed peptide amphiphiles (PAs), to construct antiviral prodrug hydrogelators (TFV-PAs). The resultant conjugates can self-assemble into one-dimensional nanostructures in aqueous environments and consequently undergo rapid gelation upon injection into 1× PBS solution to create a drug depot. The TFV-PA designs containing two or three valines could attain instantaneous gelation, with one displaying sustained release for more than 28 days in vitro. Our studies suggest that minor changes in peptide design can result in differences in supramolecular morphology and structural stability, which impacted in vitro gelation and release. We envision the use of this system as an important delivery platform for the sustained, linear release of TFV at rates that can be precisely tuned to attain therapeutically relevant TFV plasma concentrations.

Advances in Immunotherapy for Hepatitis B

Hepatitis B virus (HBV) is a hepatotropic virus with the potential to cause chronic infection, and it is one of the common causes of liver disease worldwide. Chronic HBV infection leads to liver cirrhosis and, ultimately, hepatocellular carcinoma (HCC). The persistence of covalently closed circular DNA (cccDNA) and the impaired immune response in patients with chronic hepatitis B (CHB) has been studied over the past few decades. Despite advances in the etiology of HBV and the development of potent virus-suppressing regimens, a cure for HBV has not been found. Both the innate and adaptive branches of immunity contribute to viral eradication. However, immune exhaustion and evasion have been demonstrated during CHB infection, although our understanding of the mechanism is still evolving. Recently, the successful use of an antiviral drug for hepatitis C has greatly encouraged the search for a cure for hepatitis B, which likely requires an approach focused on improving the antiviral immune response. In this review, we discuss our current knowledge of the immunopathogenic mechanisms and immunobiology of HBV infection. In addition, we touch upon why the existing therapeutic approaches may not achieve the goal of a functional cure. We also propose how combinations of new drugs, and especially novel immunotherapies, contribute to HBV clearance.

Economic Evaluation of Oral Nucleos(t)ide Analogues for Patients with Chronic Hepatitis B in Thailand

BACKGROUND

Nucleos(t)ide analogues (NAs) are the main drug category used in the treatment of chronic hepatitis B (CHB). There is a need to update the economic evaluation of CHB treatment.

OBJECTIVE

This study aimed to determine the cost effectiveness of NAs for CHB in Thailand.

METHOD

We used a lifetime Markov model undertaken from a societal perspective. Tenofovir disoproxil fumarate (TDF), tenofovir alafenamide fumarate (TAF), entecavir (ETV) with TDF or TAF as rescue medications, and lamivudine (LAM) with TDF or TAF rescue medications were compared with best supportive care (BSC). We performed a network meta-analysis to estimate the treatment effects of each NA on hepatitis B surface antigen (HBsAg) loss in an Asian population and performed an additional literature review to identify inputs. We calculated incremental cost-effectiveness ratios (ICERs) per quality-adjusted life-years (QALYs) and performed sensitivity analyses.

RESULTS

Compared with BSC, all NAs could improve patients' QALYs, with results ranging from 4.04 to 4.25 QALYs gained. TAF, TDF, LAM/TAF, and LAM/TDF yielded lower total lifetime costs than BSC, ranging from - $US1387 to - 814, whereas ETV/TAF and ETV/TDF yielded higher total lifetime costs than BSC, ranging from $US4965 to 4971. The ICER was $US1230/QALY for ETV/TDF and $US1228/QALY for ETV/TAF. Full incremental analysis showed that the ICER for LAM/TAF was $US1720/QALY compared with TAF.

CONCLUSION

At current prices, TAF, TDF, LAM/TAF, and LAM/TDF are dominant options, and ETV/TAF or ETV/TDF are cost-effective options. LAM/TAF is the most cost-effective option, followed by TAF.

Effect of an Electronic Alert System on Hepatitis B Virus Reactivation in Patients Receiving Immunosuppressive Drug Therapy

Hepatitis B virus (HBV) reactivation (HBVr) can occur in patients receiving immunosuppressive drug therapies, causing significant morbidity and mortality. Although the guidelines for HBVr have been proposed by several academic societies, some providers do not follow them, resulting in HBVr and death. As HBV-DNA levels increase before liver enzyme levels do, we previously constructed an electronic alert system that recommends the measurement of HBV-DNA. Here, we investigated whether this alert system improves the HBV-DNA measurement rate and elicits responses according to guidelines. A total of 5329 patients were divided into two groups, before and after the introduction of the alert system, and the HBV-DNA measurement rates in both groups were compared. Because of the introduction of the alert system, the HBV-DNA measurement rate among HBsAg-negative patients with anti-HBs and/or anti-HBc before immunosuppressive drug therapy improved significantly. The HBV-DNA monitoring rate within 3 months also improved significantly (p = 0.0034) in HBV-remission phase patients. HBVr was detected immediately, and the affected patients were treated with nucleotide analogs before severe hepatitis onset. The introduction of the alert system for HBVr improved the HBV-DNA measurement rates in patients receiving immunosuppressive drug therapy, leading to the rapid treatment of patients with HBVr.

Intracellular interferon signalling pathways as potential regulators of covalently closed circular DNA in the treatment of chronic hepatitis B

Infection with the hepatitis B virus (HBV) is still a major global health threat as 250 million people worldwide continue to be chronically infected with the virus. While patients may be treated with nucleoside/nucleotide analogues, this only suppresses HBV titre to sub-detection levels without eliminating the persistent HBV covalently closed circular DNA (cccDNA) genome. As a result, HBV infection cannot be cured, and the virus reactivates when conditions are favorable. Interferons (IFNs) are cytokines known to induce powerful antiviral mechanisms that clear viruses from infected cells. They have been shown to induce cccDNA clearance, but their use in the treatment of HBV infection is limited as HBV-targeting immune cells are exhausted and HBV has evolved multiple mechanisms to evade and suppress IFN signalling. Thus, to fully utilize IFN-mediated intracellular mechanisms to effectively eliminate HBV, instead of direct IFN administration, novel strategies to sustain IFN-mediated anti-cccDNA and antiviral mechanisms need to be developed. This review will consolidate what is known about how IFNs act to achieve its intracellular antiviral effects and highlight the critical interferon-stimulated gene targets and effector mechanisms with potent anti-cccDNA functions. These include cccDNA degradation by APOBECs and cccDNA silencing and transcription repression by epigenetic modifications. In addition, the mechanisms that HBV employs to disrupt IFN signalling will be discussed. Drugs that have been developed or are in the pipeline for components of the IFN signalling pathway and HBV targets that detract IFN signalling mechanisms will also be identified and discussed for utility in the treatment of HBV infections. Together, these will provide useful insights into design strategies that specifically target cccDNA for the eradication of HBV.

Implications of Birth-Dose Vaccination against Hepatitis B Virus in Southeast Asia

The World Health Organization (WHO) South-East Asia Regional Office (SEARO) covers 11 countries with a combined population of about 2 billion people, making it the most populous of the six WHO regions. In 1992, the WHO advocated including the hepatitis B vaccine in the Expanded Program of Immunization (EPI) and vaccinating all infants and children three times within 1 year of birth (HepB3). Recently, the WHO advocate birth-dose hepatitis B vaccination (HepB-BD) as soon as possible after birth, preferably within 24 hours. In 2016, the SEARO endorsed a regional hepatitis B control goal with a target of hepatitis B surface antigen (HBsAg) seroprevalence of ≤1% among children aged ≥5 years by 2020. Of the 11 SEARO countries, four achieved this target on schedule. Out of these four countries, two countries (Bangladesh and Nepal) have not adopted HepB-BD in EPI program. On the other hand, the coverage of HepB3 is not satisfactory in some SEARO countries, including India which adopted HepB-BD but could not achieve the overall target of SEARO. Thus, it is a point of debate whether emphasis should be placed on proper implementation of HepB3 or whether a new agenda of HepB-BD should be incorporated in developing countries of SEARO. The article discusses strengthening and expanding the Hepatitis B vaccination program in SEARO countries with an emphasis on HepB and HepB-BD programs.

The current status of virus-positive liver transplantation

PURPOSE OF REVIEW

The last 2 years have seen significant developments in virus-positive liver transplantation. This review provides an updated account of the transplantation of hepatitis C virus (HCV), hepatitis B virus (HBV) and HIV-positive livers, with a specific focus on studies published in the last 18 months.

RECENT FINDINGS

The advent of highly efficacious direct acting antiviral agents, nucleos(t)ide analogues and a continued organ shortage have led to the well tolerated utilization of HCV, HBV and HIV-positive organs. There has been a significant increase in the transplantation of HCV seropositive and NAT+ organs into HCV-negative recipients, without compromising patient or graft survival. Early reports of HBV core antibody (HBVcAb), HBV surface antigen (HBVsAg) positive and NAT+ donors are growing in the USA with promising results. Similarly, small studies have described the use of HIV-positive to HIV-positive liver transplantation without concerns for superinfection.

SUMMARY

HCV, HBV and HIV-positive liver transplantations can be accomplished safely and are associated with equivalent outcomes when paired with appropriate recipients. The practice of virus positive liver transplantation should be encouraged to combat the ongoing organ shortage.

Suppression of hepatitis B virus through therapeutic activation of RIG-I and IRF3 signaling in hepatocytes

Hepatitis B virus (HBV) mediates persistent infection, chronic hepatitis, and liver disease. HBV covalently closed circular (ccc)DNA is central to viral persistence such that its elimination is considered the cornerstone for HBV cure. Inefficient detection by pathogen recognition receptors (PRRs) in the infected hepatocyte facilitates HBV persistence via avoidance of innate immune activation and interferon regulatory factor (IRF)3 induction of antiviral gene expression. We evaluated a small molecule compound, F7, and 5'-triphosphate-poly-U/UC pathogen-associated-molecular-pattern (PAMP) RNA agonists of RIG-I, a PRR that signals innate immunity, for ability to suppress cccDNA. F7 and poly-U/UC PAMP treatment of HBV-infected cells induced RIG-I signaling of IRF3 activation to induce antiviral genes for suppression of cccDNA formation and accelerated decay of established cccDNA, and were additive to the actions of entecavir. Our study shows that activation of the RIG-I pathway and IRF3 to induce innate immune actions offers therapeutic benefit toward elimination of cccDNA.

Chapter XX Antiviral Treatment and Cancer Control

Hepatitis B virus (HBV), hepatitis C virus (HCV), human papilloma virus (HPV), Epstein-Barr virus (EBV), human T-cell lymphotropic virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), and Merkel cell polyomavirus (MCV) contribute to about 10-15% global burden of human cancers. Conventional chemotherapy or molecular target therapies have been used to treat virus-associated cancers. However, a more proactive approach would be the use of antiviral treatment to suppress or eliminate viral infections to prevent the occurrence of cancer in the first place. Antiviral treatments against chronic HBV and HCV infection have achieved this goal, with significant reduction in the incidence of hepatocellular carcinoma in treated patients. Antiviral treatments for EBV, KSHV, and HTLV-1 had limited success in treating refractory EBV-associated lymphoma and post-transplant lymphoproliferative disorder, KSHV-associated Kaposi's sarcoma in AIDS patients, and HTLV-1-associated acute, chronic, and smoldering subtypes of adult T-cell lymphoma, respectively. Therapeutic HPV vaccine and RNA interference-based therapies for treating HPV-associated infection or cervical cancers also showed some encouraging results. Taken together, antiviral therapies have yielded promising results in cancer prevention and treatment. More large-scale studies in a real-world setting are necessary to confirm the efficacy of antiviral therapy. Further investigation for more effective and convenient antiviral regimens warrants more attention.

Interferon Alpha Induces Multiple Cellular Proteins That Coordinately Suppress Hepadnaviral Covalently Closed Circular DNA Transcription

Covalently closed circular DNA (cccDNA) of hepadnaviruses exists as an episomal minichromosome in the nucleus of an infected hepatocyte and serves as the template for the transcription of viral mRNAs. It had been demonstrated by others and us that interferon alpha (IFN-α) treatment of hepatocytes induced a prolonged suppression of human and duck hepatitis B virus cccDNA transcription, which is associated with the reduction of cccDNA-associated histone modifications specifying active transcription (H3K9^ac or H3K27^ac), but not the histone modifications marking constitutive (H3K9^me3) or facultative (H3K27^me3) heterochromatin formation. In our efforts to identify IFN-induced cellular proteins that mediate the suppression of cccDNA transcription by the cytokine, we found that downregulating the expression of signal transducer and activator of transcription 1 (STAT1), structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1), or promyelocytic leukemia (PML) protein increased basal level of cccDNA transcription activity and partially attenuated IFN-α suppression of cccDNA transcription. In contrast, ectopic expression of STAT1, SMCHD1, or PML significantly reduced cccDNA transcription activity. SMCHD1 is a noncanonical SMC family protein and implicated in epigenetic silencing of gene expression. PML is a component of nuclear domain 10 (ND10) and is involved in suppressing the replication of many DNA viruses. Mechanistic analyses demonstrated that STAT1, SMCHD1, and PML were recruited to cccDNA minichromosomes and phenocopied the IFN-α-induced posttranslational modifications of cccDNA-associated histones. We thus conclude that STAT1, SMCHD1, and PML may partly mediate the suppressive effect of IFN-α on hepadnaviral cccDNA transcription.IMPORTANCE Pegylated IFN-α is the only therapeutic regimen that can induce a functional cure of chronic hepatitis B in a small, but significant, fraction of treated patients. Understanding the mechanisms underlying the antiviral functions of IFN-α in hepadnaviral infection may reveal molecular targets for development of novel antiviral agents to improve the therapeutic efficacy of IFN-α. By a loss-of-function genetic screening of individual IFN-stimulated genes (ISGs) on hepadnaviral mRNAs transcribed from cccDNA, we found that downregulating the expression of STAT1, SMCHD1, or PML significantly increased the level of viral RNAs without altering the level of cccDNA. Mechanistic analyses indicated that those cellular proteins are recruited to cccDNA minichromosomes and induce the posttranslational modifications of cccDNA-associated histones similar to those induced by IFN-α treatment. We have thus identified three IFN-α-induced cellular proteins that suppress cccDNA transcription and may partly mediate IFN-α silencing of hepadnaviral cccDNA transcription.

Targeting the multifunctional HBV core protein as a potential cure for chronic hepatitis B

The core (capsid) protein of hepatitis B virus (HBV) is the building block of nucleocapsids where viral DNA reverse transcriptional replication takes place and mediates virus-host cell interaction important for the persistence of HBV infection. The pleiotropic role of core protein (Cp) in HBV replication makes it an attractive target for antiviral therapies of chronic hepatitis B, a disease that affects more than 257 million people worldwide without a cure. Recent clinical studies indicate that core protein allosteric modulators (CpAMs) have a great promise as a key component of hepatitis B curative therapies. Particularly, it has been demonstrated that modulation of Cp dimer-dimer interactions by several chemical series of CpAMs not only inhibit nucleocapsid assembly and viral DNA replication, but also induce the disassembly of double-stranded DNA-containing nucleocapsids to prevent the synthesis of cccDNA. Moreover, the different chemotypes of CpAMs modulate Cp assembly by interaction with distinct amino acid residues at the HAP pocket between Cp dimer-dimer interfaces, which results in the assembly of Cp dimers into either non-capsid Cp polymers (type I CpAMs) or empty capsids with distinct physical property (type II CpAMs). The different CpAMs also differentially modulate Cp metabolism and subcellular distribution, which may impact cccDNA metabolism and host antiviral immune responses, the critical factors for the cure of chronic HBV infection. This review article highlights the recent research progress on the structure and function of core protein in HBV replication cycle, the mode of action of CpAMs, as well as the current status and perspectives on the discovery and development of core protein-targeting antivirals. This article forms part of a symposium in Antiviral Research on "Wide-ranging immune and direct-acting antiviral approaches to curing HBV and HDV infections."

Protein phosphatase 1 catalyzes HBV core protein dephosphorylation and is co-packaged with viral pregenomic RNA into nucleocapsids

Hepatitis B virus (HBV) replicates its genomic DNA via viral DNA polymerase self-primed reverse transcription of a RNA pre-genome in the nucleocapsid assembled by 120 core protein (Cp) dimers. The arginine-rich carboxyl-terminal domain (CTD) of Cp plays an important role in the selective packaging of viral DNA polymerase-pregenomic (pg) RNA complex into nucleocapsid. Previous studies suggested that the CTD is initially phosphorylated at multiple sites to facilitate viral RNA packaging and subsequently dephosphorylated in association with viral DNA synthesis and secretion of DNA-containing virions. However, our recent studies suggested that Cp is hyper-phosphorylated as free dimers and its dephosphorylation is associated with pgRNA encapsidation. Herein, we provide further genetic and biochemical evidence supporting that extensive Cp dephosphorylation does take place during the assembly of pgRNA-containing nucleocapsids, but not empty capsids. Moreover, we found that cellular protein phosphatase 1 (PP1) is required for Cp dephosphorylation and pgRNA packaging. Interestingly, the PP1 catalytic subunits α and β were packaged into pgRNA-containing nucleocapsids, but not empty capsids, and treatment of HBV replicating cells with core protein allosteric modulators (CpAMs) promoted empty capsid assembly and abrogated the encapsidation of PP1 α and β. Our study thus identified PP1 as a host cellular factor that is co-packaged into HBV nucleocapsids, and plays an essential role in selective packaging of the viral DNA-polymerase-pgRNA complex through catalyzing Cp dephosphorylation.

Selective packaging of pregenomic RNA by core protein dimers into nucleocapsid is a key step of HBV replication and is subjected for the regulation by multiple viral and host cellular factors. HBV core protein phosphorylation and dephosphorylation play an essential role in HBV genome replication. However, the cellular kinases and phosphatases responsible for the biochemical events remain elusive. Identification of cellular protein phosphatase 1 as a host cellular factor catalyzing core protein dephosphorylation and facilitating viral pregenomic RNA packaging into nucleocapsids sheds new light on the molecular mechanism of HBV replication and development of therapeutics to cure chronic HBV infection.

Impacts of HBV rtH55R polymerase substitution on viral replication and rtM204I/V resistance to nucleoside/nucleotide antiviral drugs

BACKGROUND

High genetic variability at the reverse transcriptase (RT) region of HBV could confer resistance to nucleoside/nucleotide analogues (NUCs). The aim of this study was to identify new RT amino acid (AA) substitutions related to NUC resistance.

METHODS

HBV RT sequences of genotype C from 501 chronic hepatitis B (CHB) patients were analysed to identify potential RT substitutions related to NUC resistance. In vitro studies without and with NUCs were performed in a HepG2 cell line transfected by clones with RT harbouring wild-type or substituted AA(s) of interest.

RESULTS

Among 261 NUC-treated CHB patients, we found a high detection rate of rtM204I/V substitution (30.7% [80/261]). We identified a new substitution of rtH55R, and its detection rate had a significantly increasing trend from 3.8% (9/240) in the untreated group to 7.2% (13/181) or 33.8% (27/80) in the treated group with rtM204 or with rtM204I/V substitutions (P<0.0001). In vitro studies showed that rtH55R had a similar HBV DNA level compared to wild type. The rtH55R+rtM204I clone had a significantly better replication capacity than the rtM204I clone without NUCs (P<0.05). The replication capacity of the rtM204I clone was found to significantly decrease under lamivudine treatment, but this was not found in the rtH55R+rtM204I clone.

CONCLUSIONS

We identified a new HBV RT substitution of rtH55R in genotype-C-infected CHB patients. It is frequently found in combination with rtM204I/V substitution under NUC treatment. In vitro studies suggest that it might play some replication compensatory role in rtM204I mutants under lamivudine treatment.

Antiviral treatment for treatment-naïve chronic hepatitis B: systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Chronic hepatitis B (CHB) infection poses a significant burden to public health worldwide. Most cases are clinically silent until late in the disease course. The main goal of current therapy is to improve survival and quality of life by preventing disease progression to cirrhosis and liver failure, and consequently hepatocellular carcinoma development. The objective of this review is to provide a contemporary and comprehensive evaluation of the effectiveness of treatment options.

METHODS

We performed a systematic review of peer-reviewed literature for randomized controlled trials involving treatment-naïve CHB adult population who received antiviral therapy. The endpoints were virologic response (VR), normalization of alanine aminotransferase (ALT norm), HBeAg loss, HBeAg seroconversion, and HBsAg loss for the HBeAg-positive population; and VR and ALT norm for the HBeAg-negative population. Network meta-analysis (NMA) was performed to synthesize evidence on the efficacy of treatment.

RESULTS

Forty-two publications were selected. Twenty-three evaluated HBeAg-positive population, 13 evaluated HBeAg-negative population, and six evaluated both. We applied NMA to the efficacy outcomes of the two populations separately. Treatment strategies were ranked by the probability of achieving outcomes, and pairwise comparisons calculated from NMA were reported in odds ratios (OR). For HBeAg-positive population, tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) were the best for VR; OR vs adefovir = 14.29, 95% CI 7.69-25 and 12.5, 95% CI 4.35-33.33 respectively. TAF was the best for achieving ALT norm (OR vs placebo = 12.5, 95% CI 4.55-33.33), HBeAg loss, and seroconversion (OR vs entecavir/TDF combination = 3.03, 95% CI 1.04-8.84 and 3.33, 95% CI 1.16-10 respectively). In the HBeAg-negative population, TDF and TAF were the best for VR (OR vs adefovir = 9.79, 95% CI 2.38-42.7 and 11.71, 95% CI 1.03-150.48 respectively). Telbivudine and TAF were the best for ALT norm. Certain nucleos(t)ide combinations also had high probability of achieving positive outcomes.

CONCLUSIONS

Our results are consonant with current clinical guidelines and other evidence reviews. For both HBeAg-positive and HBeAg-negative populations, TDF and TAF are the most effective agents for virologic suppression, and TAF is effective across all outcomes.

Treatment Outcome and Renal Safety of 3-Year Tenofovir Disoproxil Fumarate Therapy in Chronic Hepatitis B Patients with Preserved Glomerular Filtration Rate

Background/Aims

To investigate the treatment efficacy and renal safety of long-term tenofovir disoproxil fumarate (TDF) therapy in chronic hepatitis B (CHB) patients with preserved renal function.

Methods

The medical records of 919 CHB patients who were treated with TDF therapy were reviewed. All patients had preserved renal function with an estimated glomerular filtration rate (eGFR) of at least 60 mL/min/1.73 m².

Results

A total of 426 patients (184 treatment-naïve and 242 treatment-experienced) were included for analysis. A virologic response (VR) was defined as achieving an undetectable serum hepatitis B virus (HBV) DNA level, and the overall VR was 74.9%, 86.7%, and 89.4% at the 1, 2, and 3-year follow-ups, respectively. Achieving a VR was not influenced by previous treatment experience, TDF combination therapy, or antiviral resistance. In a multivariate analysis, being hepatitis B e antigen positive at baseline and having a serum HBV DNA level ≥2,000 IU/mL at 12 months were associated with lower VR rates during the long-term TDF therapy. The overall renal impairment was 2.9%, 1.8%, and 1.7% at the 1, 2, and 3-year follow-ups, respectively. With regard to renal safety, underlying diabetes mellitus (DM) and an initial eGFR of 60 to 89 mL/min/1.73 m² were significant independent predictors of renal impairment.

Conclusions

TDF therapy appears to be an effective treatment option for CHB patients with a preserved GFR. However, patients with underlying DM and initial mild renal dysfunction (eGFR, 60 to 89 mL/min/1.73 m²) have an increased risk of renal impairment.

Cellular DNA Topoisomerases Are Required for the Synthesis of Hepatitis B Virus Covalently Closed Circular DNA

In order to identify host cellular DNA metabolic enzymes that are involved in the biosynthesis of hepatitis B virus (HBV) covalently closed circular (ccc) DNA, we developed a cell-based assay supporting synchronized and rapid cccDNA synthesis from intracellular progeny nucleocapsid DNA. This was achieved by arresting HBV DNA replication in HepAD38 cells with phosphonoformic acid (PFA), a reversible HBV DNA polymerase inhibitor, at the stage of single-stranded DNA and was followed by removal of PFA to allow the synchronized synthesis of relaxed circular DNA (rcDNA) and subsequent conversion into cccDNA within 12 to 24 h. This cccDNA formation assay allows systematic screening of the effects of small molecular inhibitors of DNA metabolic enzymes on cccDNA synthesis but avoids cytotoxic effects upon long-term treatment. Using this assay, we found that all the tested topoisomerase I and II (TOP1 and TOP2, respectively) poisons as well as topoisomerase II DNA binding and ATPase inhibitors significantly reduced the levels of cccDNA. It was further demonstrated that these inhibitors also disrupted cccDNA synthesis during de novo HBV infection of HepG2 cells expressing sodium taurocholate cotransporting polypeptide (NTCP). Mechanistic analyses indicate that whereas TOP1 inhibitor treatment prevented the production of covalently closed negative-strand rcDNA, TOP2 inhibitors reduced the production of this cccDNA synthesis intermediate to a lesser extent. Moreover, small interfering RNA (siRNA) knockdown of topoisomerase II significantly reduced cccDNA amplification. Taking these observations together, our study demonstrates that topoisomerase I and II may catalyze distinct steps of HBV cccDNA synthesis and that pharmacologic targeting of these cellular enzymes may facilitate the cure of chronic hepatitis B.IMPORTANCE Persistent HBV infection relies on stable maintenance and proper functioning of a nuclear episomal form of the viral genome called cccDNA, the most stable HBV replication intermediate. One of the major reasons for the failure of currently available antiviral therapeutics to cure chronic HBV infection is their inability to eradicate or inactivate cccDNA. We report here a chemical genetics approach to identify host cellular factors essential for the biosynthesis and maintenance of cccDNA and reveal that cellular DNA topoisomerases are required for both de novo synthesis and intracellular amplification of cccDNA. This approach is suitable for systematic screening of compounds targeting cellular DNA metabolic enzymes and chromatin remodelers for their ability to disrupt cccDNA biosynthesis and function. Identification of key host factors required for cccDNA metabolism and function will reveal molecular targets for developing curative therapeutics of chronic HBV infection.

Virological Basis for the Cure of Chronic Hepatitis B

Hepatitis B virus (HBV) has infected one-third of world population, and 240 million people are chronic carriers, to whom a curative therapy is still not available. Similar to other viruses, persistent HBV infection relies on the virus to exploit host cell functions to support its replication and efficiently evade host innate and adaptive antiviral immunity. Understanding HBV replication and concomitant host cell interactions is thus instrumental for development of therapeutics to disrupt the virus-host interactions critical for its persistence and cure chronic hepatitis B. Although the currently available cell culture systems of HBV infection are refractory to genome-wide high throughput screening of key host cellular factors essential for and/or regulating HBV replication, classic one-gene (or pathway)-at-a-time studies in the last several decades have already revealed many aspects of HBV-host interactions. An overview of the landscape of HBV-hepatocyte interaction indicates that, in addition to more tightly suppressing viral replication by directly targeting viral proteins, disruption of key viral-host cell interactions to eliminate or inactivate the covalently closed circular (ccc) DNA, the most stable HBV replication intermediate that exists as an episomal minichromosome in the nucleus of infected hepatocyte, is essential to achieve a functional cure of chronic hepatitis B. Moreover, therapeutic targeting of integrated HBV DNA and their transcripts may also be required to induce hepatitis B virus surface antigen (HBsAg) seroclearance and prevent liver carcinogenesis.

Discovery of Novel Hepatitis B Virus Nucleocapsid Assembly Inhibitors

Hepatitis B virus (HBV) core protein is a small protein with 183 amino acid residues and assembles the pregenomic (pg) RNA and viral DNA polymerase to form nucleocapsids. During the last decades, several groups have reported HBV core protein allosteric modulators (CpAMs) with distinct chemical structures. CpAMs bind to the hydrophobic HAP pocket located at the dimer-dimer interface and induce allosteric conformational changes in the core protein subunits. While Type I CpAMs, heteroaryldihydropyrimidine (HAP) derivatives, misdirect core protein dimers to assemble noncapsid polymers, Type II CpAMs, represented by sulfamoylbenzamides, phenylpropenamides, and several other chemotypes, induce the assembly of empty capsids with global structural alterations and faster mobility in native agarose gel electrophoresis. Through high throughput screening of an Asinex small molecule library containing 19 920 compounds, we identified 8 structurally distinct CpAMs. While 7 of those compounds are typical Type II CpAMs, a novel benzamide derivative, designated as BA-53038B, induced the formation of morphologically "normal" empty capsids with slow electrophoresis mobility. Drug resistant profile analyses indicated that BA-53038B most likely bound to the HAP pocket but obviously modulated HBV capsid assembly in a distinct manner. BA-53038B and other CpAMs reported herein provide novel structure scaffolds for the development of core protein-targeted antiviral agents for the treatment of chronic hepatitis B.

Durability of Antibody Response Against the Hepatitis B Virus in Kidney Transplant Recipients: A Proposed Immunization Guideline From a 3-Year Follow-up Clinical Study

Background

Despite the importance of hepatitis B virus (HBV) immunization in kidney transplantation (KT), data are lacking on fluctuations in hepatitis B surface antibody (anti-HBsAb) levels and optimal levels for KT recipients.

Methods

The study consisted of anti-HBsAb-positive recipients aged 18–70 years at the time of the KT. Recipients with anti-HBsAb <100 IU/L received a single booster HBV vaccination, and anti-HBsAb was measured at baseline and 3, 6, 12, 18, and 24 months post-KT. Anti-HBsAb, quantitative HBV deoxyribonucleic acid testing (12 and 24 months post-KT), and hepatitis B core-related antigen (24 months post-KT) were evaluated in recipients with anti-HBsAb >100 IU/L who received a hepatitis B surface antigen positive renal allograft.

Results

Seventy-six of 257 (29.6%) KT recipients with anti-HBsAb <100 IU/L at the time of enrollment received a single booster of HBV vaccination. Anti-HBsAb levels increased (≥100 IU/L) 1 and 3 months post-booster dose in 86% and 93% of cases, respectively. Anti-HBsAb levels were ≥100 IU/L in 95% of these recipients 6 months post-booster dose. Among 181 (70%) recipients with anti-HBsAb ≥100 IU/L without a booster dose, anti-HBsAb gradually decreased after the KT from 588 IU/L at baseline to 440 and 382 IU/L 3 and 6 months post-KT, respectively (P < .01).

Conclusions

To ensure optimal immunity against HBV, KT recipients should first be stratified according to their risk of HBV reactivation. Kidney transplantation recipients of renal allografts from HBV nonviremic or viremic donors should be reimmunized when their anti-HBsAb titers are <250 IU/L. A cutoff level of 100 IU/L is recommended in other cases.

Predictors of Therapeutic Outcome to Nucleotide Reverse Transcriptase Inhibitor in Hepatitis B Patients

Hepatitis B is a clinically important public health issue. Infection leads to hepatocellular carcinoma. Therefore, patients need antiviral therapy for prolonged period to prevent the complication of the disease. Data concerning chronic hepatitis B (CHB) patients with high hepatitis B virus (HBV) DNA are limited. The aim of the study was to check the efficacy of the nucleoside reverse transcriptase inhibitors (tenofovir) in terms of suppression of HBV DNA. The secondary end point in the study is to evaluate trends of predictive variables that predict outcome of treatment. In this specific study, we evaluated 140 CHB male and female patients, of these 110 completed 48 weeks of treatment. On the basis of hepatitis B e antigen (HBeAg), patients were stratified; HBV DNA and hepatitis B surface antigen (HBsAg) levels were measured along with liver function tests. All enrolled patients were given tenofovir disoproxil fumarate 300 mg daily before breakfast. Overall, 69.1% of patients showed virologic response. HBeAg-negative patient group showed 68% viral suppression and HBeAg-positive patient group showed 45.9% over 24 months of treatment, while at 48 months it was shown to be 76.7% and 54.1%, respectively. None of the patients suffered HBsAg loss during the 48 months. Baseline high HBV DNA level was found as a significant predictor of response (OR, 1.9; 95% CI = 1.23-3.9, p = 0.005). None of the patients observed had serious adverse events. Mutations in the RT region of polymerase gene are shown to be associated with resistance to antiviral drugs. Among patients suffering with chronic HBV infection, HBeAg-negative patient group have better virologic response as compared with HBeAg-positive group. Higher concentration of HBV DNA at baseline has negative prediction for sustained viral suppression. The A-B motif interdomain rtL122F mutation was found in nonresponder patients in our study. Another mutation rtN248H observed in E motif considered to have effect on DNA primer grip, which forms part of binding pocket.

The Hepatitis B Surface Antigen Binding Protein: An Immunoglobulin G Constant Region-Like Protein That Interacts With HBV Envelop Proteins and Mediates HBV Entry

Hepatitis B virus (HBV) infection is a leading cause of liver cirrhosis, liver cancer, and liver failure, affecting 350 million people worldwide. Currently available anti-HBV drugs include (PEGylated-) interferon-α and nucleos(t)ide analogs, which can cause significant side effects and drug-resistance in many cases of long-term treatment. The lack of a reliable and robust in vitro infection system is a major barrier for understanding the HBV life cycle and discovering novel therapeutic targets. In the present study, we demonstrate that overexpression of the hepatitis B surface antigen binding protein (SBP) in HepG2 cells (HepG2-SBP) resulted in their susceptibility to HBV infection. HepG2-SBP cells supported the uptake of the viral surface protein (HBsAg-preS), HBV-pseudotyped virus, and live HBV in patient sera. Moreover, SBP-mediated HBsAg-preS uptake, and HBV pseudotyped virus infections were efficiently blocked by preS1- and SBP-specific antibodies. These observations suggest that SBP is involved in HBV entry and that HepG2-SBP cells can serve as a cellular model to study the post-binding steps of HBV infection.

CpAMs induce assembly of HBV capsids with altered electrophoresis mobility: Implications for mechanism of inhibiting pgRNA packaging

Native agarose gel electrophoresis-based particle gel assay has been commonly used for examination of hepatitis B virus (HBV) capsid assembly and pregenomic RNA encapsidation in HBV replicating cells. Interestingly, treatment of cells with several chemotypes of HBV core protein allosteric modulators (CpAMs) induced the assembly of both empty and DNA-containing capsids with faster electrophoresis mobility. In an effort to determine the physical basis of CpAM-induced capsid mobility shift, we found that the surface charge, but not the size, of capsids is the primary determinant of electrophoresis mobility. Specifically, through alanine scanning mutagenesis analysis of twenty-seven charged amino acids in core protein assembly domain and hinge region, we showed that except for K7 and E8, substitution of glutamine acid (E) or aspartic acid (D) on the surface of capsids reduced their mobility, but substitution of lysine (K) or arginine (R) on the surface of capsids increased their mobility in variable degrees. However, alanine substitution of the charged amino acids that are not exposed on the surface of capsid did not apparently alter capsid mobility. Hence, CpAM-induced electrophoresis mobility shift of capsids may reflect the global alteration of capsid structure that changes the exposure and/or ionization of charged amino acid side chains of core protein. Our findings imply that CpAM inhibition of pgRNA encapsidation is possibly due to the assembly of structurally altered nucleocapsids. Practically, capsid electrophoresis mobility shift is a diagnostic marker of compounds that target core protein assembly and predicts sensitivity of HBV strains to specific CpAMs.

48-Week Outcome after Cessation of Nucleos(t)ide Analogue Treatment in Chronic Hepatitis B Patient and the Associated Factors with Relapse

Background and Aims

We aimed to ascertain the feasibility and safety of NA cessation, the status of patients after cessation, and the predictive factors for relapse and subsequent retreatment.

Methods

A total of 92 patients were enrolled in this prospective study. Patients were monitored every month for the first 3 months after cessation and every 3 months thereafter.

Results

Sixty-two patients finished 48 weeks of follow-up. None died or developed liver failure, cirrhosis, or HCC. The 62 patients could be divided into 4 categories according to the 48-week clinical development of relapse. Virologic relapses occurred in 39 (62.9%) patients, with 72.7% occurring in the first 24 weeks in origin HBeAg positive patients and 82.4% in the first 12 weeks in origin HBeAg negative patients. Age (OR = 1.06, 95% CI = 1.02-1.10; p = 0.003), the HBsAg level (OR = 2.21, 95% CI = 1.47-3.32; p < 0.001), and positive origin HBeAg status (OR = 0.32, 95% CI = 0.14-0.74; p = 0.008) were predictive factors to virologic relapse. HBV DNA level (OR = 1.34, 95% CI = 1.13-1.58; p < 0.001) was predictive factor to retreatment.

Conclusions

NA cessation is safe under supervision. Age, HBsAg level, and origin HBeAg status can be predictive factors for virologic relapse. The study was submitted to ClinicalTrials.gov Protocol Registration and Results System with the assigned NCT ID NCT02883647.

Activation of Stimulator of Interferon Genes in Hepatocytes Suppresses the Replication of Hepatitis B Virus

Induction of interferon and proinflammatory cytokines is a hallmark of the infection of many different viruses. However, hepatitis B virus (HBV) does not elicit a detectable cytokine response in infected hepatocytes. In order to investigate the molecular mechanism underlying the innate immune evasion, a functional cyclic GMP-AMP (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway was reconstituted in a human hepatoma cell line supporting tetracycline-inducible HBV replication. It was demonstrated that induction of HBV replication neither activated nor inhibited this cytosolic DNA sensing pathway. However, human hepatoma cells, as well as immortalized mouse hepatocytes, express low levels of STING, which upon activation by cGAMP, the natural ligand of STING, led to induction of a proinflammatory cytokine response. Treatment of immortalized mouse hepatocytes supporting HBV replication with either cGAMP or a small molecule pharmacologic STING agonist significantly reduced viral DNA in a STING- and Janus kinase 1-dependent manner. Moreover, cGAMP treatment was able to induce inflammatory cytokine gene expression and inhibit the transcription of covalently closed circular DNA in HBV-infected human hepatoma cells expressing sodium taurocholate cotransporting polypeptide, an essential receptor for HBV infection of hepatocytes. The studies reported here and previously (F. Guo et al., Antimicrob Agents Chemother 59:1273-1281, 2015, https://doi.org/10.1128/AAC.04321-14) thus support the notion that pharmacological activation of STING in macrophages and hepatocytes induces host innate responses that can efficiently control HBV replication. Hence, despite not playing a significant role in host innate immune response to HBV infection of hepatocytes, STING is potentially a valuable target for immunotherapy of chronic hepatitis B.

Discovery and Mechanistic Study of Benzamide Derivatives That Modulate Hepatitis B Virus Capsid Assembly

Chronic hepatitis B virus (HBV) infection is a global public health problem. Although the currently approved medications can reliably reduce the viral load and prevent the progression of liver diseases, they fail to cure the viral infection. In an effort toward discovery of novel antiviral agents against HBV, a group of benzamide (BA) derivatives that significantly reduced the amount of cytoplasmic HBV DNA were discovered. The initial lead optimization efforts identified two BA derivatives with improved antiviral activity for further mechanistic studies. Interestingly, similar to our previously reported sulfamoylbenzamides (SBAs), the BAs promote the formation of empty capsids through specific interaction with HBV core protein but not other viral and host cellular components. Genetic evidence suggested that both SBAs and BAs inhibited HBV nucleocapsid assembly by binding to the heteroaryldihydropyrimidine (HAP) pocket between core protein dimer-dimer interfaces. However, unlike SBAs, BA compounds uniquely induced the formation of empty capsids that migrated more slowly in native agarose gel electrophoresis from A36V mutant than from the wild-type core protein. Moreover, we showed that the assembly of chimeric capsids from wild-type and drug-resistant core proteins was susceptible to multiple capsid assembly modulators. Hence, HBV core protein is a dominant antiviral target that may suppress the selection of drug-resistant viruses during core protein-targeting antiviral therapy. Our studies thus indicate that BAs are a chemically and mechanistically unique type of HBV capsid assembly modulators and warranted for further development as antiviral agents against HBV.IMPORTANCE HBV core protein plays essential roles in many steps of the viral replication cycle. In addition to packaging viral pregenomic RNA (pgRNA) and DNA polymerase complex into nucleocapsids for reverse transcriptional DNA replication to take place, the core protein dimers, existing in several different quaternary structures in infected hepatocytes, participate in and regulate HBV virion assembly, capsid uncoating, and covalently closed circular DNA (cccDNA) formation. It is anticipated that small molecular core protein assembly modulators may disrupt one or multiple steps of HBV replication, depending on their interaction with the distinct quaternary structures of core protein. The discovery of novel core protein-targeting antivirals, such as benzamide derivatives reported here, and investigation of their antiviral mechanism may lead to the identification of antiviral therapeutics for the cure of chronic hepatitis B.

Influences on viral replication and sensitivity to GLS4, a HAP compound, of naturally occurring T109/V124 mutations in hepatitis B virus core protein

Heteroaryldihydropyrimidine (HAP) compounds inhibit HBV replication by binding to a hydrophobic pocket at the interface between hepatitis B virus core protein (HBcAg) dimer, which interrupts capsid assembly by changing the kinetics and thermodynamics during this process. Structure biological studies have identified several amino acids in HBcAg crucial for compound binding. Here, we investigated the polymorphisms of T109 and V124 amino acids in HBV sequences submitted to GenBank database. Naturally occurring T109 and V124 and/or possible compensatory mutations in neighbored amino acids were introduced into HBV-expressing plasmids. Viral replication competence and sensitivity to GLS4, a HAP compound, were evaluated using transient transfection and in vitro infection cell models. All tested mutations in these amino acids led to decreasing viral DNA replication at different levels. Specially, T109N and all V124 mutants caused severe deficiencies in viral plus-strand DNA synthesis. T109I single mutation and all T109S/M/C/N mutations impaired HBeAg secretion. T109I showed modestly decreased sensitivities with IC50 3.3- to 6.8-folds higher than wild-type virus. In vitro infection assay showed T109N and all V124 mutants failed to synthesize cccDNA and following viral proteins. The other mutants, however, produced functional cccDNA pools as wild-type virus did. Taken together, we profiled the competences of viral replication and sensitivities to capsid inhibitor of naturally existing mutations in T109 and V124. This will help to understand the possible antiviral resistance issues in future clinical applications of capsid inhibitors.

T cell--associated immunoregulation and antiviral effect of oxymatrine in hydrodynamic injection HBV mouse model

Although oxymatrine (OMT) has been shown to directly inhibit the replication of hepatitis B virus (HBV) in vitro, limited research has been done with this drug in vivo. In the present study, the antiviral effect of OMT was investigated in an immunocompetent mouse model of chronic HBV infection. The infection was achieved by tail vein injection of a large volume of DNA solution. OMT (2.2, 6.7 and 20 mg/kg) was administered by daily intraperitoneal injection for 6 weeks. The efficacy of OMT was evaluated by the levels of HBV DNA, hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and hepatitis B core antigen (HBcAg). The immunoregulatory activity of OMT was evaluated by serum ELISA and flow cytometry. Results shows that OMT at 20 mg/kg inhibited HBV replication, and it was more efficient than entecavir (ETV) in the elimination of serum HBsAg and intrahepatic HBcAg. In addition, OMT accelerated the production of interferon-γ (IFN-γ) in a dose-dependent manner in CD4⁺ T cells. Our findings demonstrate the beneficial effects of OMT on the enhancement of immunological function and in the control of HBV antigens. The findings suggest this drug to be a good antiviral therapeutic candidate for the treatment of HBV infection.

Predictive value of serum ALT and T-cell receptor beta variable chain for HBeAg seroconversion in chronic hepatitis B patients during tenofovir treatment

Effective antiviral therapy plays a key role in slowing the progression of chronic hepatitis B (CHB). Identification of serum indices, including hepatitis B e antigen (HBeAg) expression and seroconversion, will facilitate evaluation of the efficacy of antiviral therapy in HBeAg-positive CHB patients. The biochemical, serological, virological parameters, and the frequency of circulating CD4CD25 regulatory T cell (Treg) in 32 patients were measured at baseline and every 12 weeks during 96 weeks of tenofovir disoproxil fumarate (TDF) treatment. The relationship between the hepatitis B virus (HBV) deoxyribonucleic acid (DNA) and Treg and alanine aminotransferase (ALT) levels was analyzed, respectively. The molecular profiles of T-cell receptor beta variable chain (TRBV) were determined using gene melting spectral pattern. For the seroconverted 12 patients, ALT declined to normal levels by week 24 and remained at this level in subsequent treatment; moreover, the predictive cutoff value of ALT for HBeAg seroconversion (SC) was 41.5 U/L at week 24. The positive correlation between HBV DNA and Treg and ALT was significant in SC patients, but not in non-SC patients. Six TRBV families (BV3, BV11, BV12, BV14, BV20, and BV24) were predominantly expressed in SC patients at baseline. The decline of ALT could be used to predict HBeAg seroconversion for CHB patients during TDF treatment. In addition, the profile of Tregs and TRBVs may be associated with HBeAg seroconversion and could also be a potential indicator for predicting HBeAg SC and treatment outcome for CHB patients.

The current status and future directions of hepatitis B antiviral drug discovery

INTRODUCTION

The current standard care of chronic hepatitis B fails to induce a durable off-drug control of hepatitis B virus (HBV) replication in the majority of treated patients. The primary reasons are its inability to eliminate the covalently closed circular (ccc) DNA, the nuclear form of HBV genome, and restoration of the dysfunctional host antiviral immune response against the virus. Accordingly, discovery and development of therapeutics to completely stop HBV replication, eliminate or functionally inactivate cccDNA as well as activate a functional antiviral immune response against HBV are the primary efforts for finding a cure for chronic hepatitis B. Area covered: Herein, the authors highlight the current efforts of HBV drug discovery and offer their opinions for the future directions of this research. Expert opinion: The authors believe that through a consecutive or overlapping three-stage antiviral and immunotherapy program to: (i) completely stop HBV replication and cccDNA amplification; (ii) reduce viral antigen load and induce HBV surface antigen (HBsAg) seroclearance through eradication or inactivation of cccDNA and RNA interference-mediated degradation of viral mRNA and (iii) activate a functional antiviral immune response against HBV through therapeutic immunization or immunotherapy, a functional cure of chronic HBV infection can be achieved in the majority of chronic HBV carriers.

Antiviral Therapy in Lamivudine-Resistant Chronic Hepatitis B Patients: A Systematic Review and Network Meta-Analysis

The relative efficacy of different strategies for chronic hepatitis B (CHB) patients with lamivudine resistance (LAM-R) has not yet been systematically studied. Clinical trials were searched in PUBMED, MEDLINE, EMBASE, and CNKI databases up to February 15, 2016. Nine trials including 764 patients met the entry criteria. In direct meta-analysis, TDF showed a stronger antiviral effect than any one of ETV, LAM/ADV, and ADV against LAM-R hepatitis B virus. LAM/ADV therapy was superior to ADV in suppressing viral replication. ETV achieved similar rate of HBV DNA undetectable compared to ADV or LAM/ADV. In network meta-analysis, TDF had higher rates of HBV DNA undetectable compared to ETV (OR, 24.69; 95% CrI: 5.36–113.66), ADV (OR, 37.28; 95% CrI: 9.73–142.92), or LAM/ADV (OR, 21.05; 95% CrI: 5.70–77.80). However, among ETV, ADV, and LAM/ADV, no drug was clearly superior to others in HBV DNA undetectable rate. Moreover, no significant difference in the rate of ALT normalization or HBeAg loss was observed compared the four rescue strategies with each other. TDF appears to be a more effective rescue therapy than LAM/ADV, ETV, or ADV. LAM plus ADV therapy was a better treatment option than ETV or ADV alone for patients with LAM-R.

Efficacy of Tenofovir-Based Combination Therapy versus Tenofovir Monotherapy in Chronic Hepatitis B Patients Presenting with Suboptimal Responses to Pretreatment: A Meta-Analysis

Background/Aims. It remains unclear whether tenofovir disoproxil fumarate- (TDF-) based combination therapy produces better outcomes than TDF monotherapy in chronic hepatitis B (CHB) patients. The aim of this study was to compare the efficacy of the two regimens by performing a meta-analysis. Methods. A comprehensive literature search was performed on the comparison of TDF-based combination therapy and monotherapy for CHB patients in the PubMed, Embase, Web of Science, and the Cochrane Libraries. Both dichotomous and continuous variables were extracted and pooled outcomes were expressed as risk ratio (RR) or standard mean difference (SMD). Results. Nine eligible studies (1089 subjects in total) were included in our analysis. The proportion of patients with undetectable HBV DNA at 24, 48, and 96 weeks were similar between the two comparable groups (62.5% versus 70.9%, P = 0.086; 78.1% versus 83.7%, P = 0.118; 86.4% versus 87.9%, P = 0.626, resp.). HBV DNA reduction, rates of ALT normalization, hepatitis B e antigen (HBeAg) loss, and HBeAg seroconversion were also similar between the two groups. Conclusions. On the current data, TDF-based combination therapy seemed to be no better than those achieved by monotherapy. Further studies are needed to verify this comparison.

Dynamics of Genotypic Mutations of the Hepatitis B Virus Associated With Long-Term Entecavir Treatment Determined With Ultradeep Pyrosequencing: A Retrospective Observational Study

The aim of the study is to explore the evolution of genotypic mutations within the reverse transcriptase region in partial virological responders (PVRs) receiving long-term entecavir (ETV) treatment. A total of 32 patients were classified as completely virological responders (CVRs) (n = 12) or PVRs (n = 20). Five partial responders were hepatitis B virus (HBV)-DNA positive after long-term therapy, which lasted for >3 years. A total of 71 serum samples from these 32 patients were assayed by ultra-deep pyrosequencing (UDPS): 32 samples were from all patients at baseline, and 39 were from PVRs with sequential inter-treatment. Approximately 84,708 sequences were generated per sample. At baseline, the quasispecies heterogeneity did not significantly differ between the 2 groups. The frequencies of substitutions indicating pre-existence of nucleos(t)ide analog resistant (NAr) mutants ranged from 0.10% to 6.70%, which did not statistically differ between groups either. However, the substitutions associated with the NAr mutants were significantly different from those associated with the non-NAr mutants in 13 patients; 6 of these patients were PVRs and the others were CVRs. Five patients were HBV DNA positive after regular ETV monotherapy for >3 years, and 4 of these patients underwent mild NAr substitution fluctuations (<20%). One patient developed virological breakthrough while bearing single, double, and triple (rtL180 M, rtM204 V, rtS202G) substitutions. In addition to the common substitutions, unknown amino acid substitutions, such as rtL145 M/S, rtF151Y/L, rtR153Q, rtI224 V, rtN248H, rtS223A, rtS256C, need to be further verified. NAr substitutions are observed at frequencies of 0.10% to 6.7% before therapy. Long-term ETV therapy generally results in virological responses, as long as the proportion of resistance mutations remains at a relatively low level. Genotypic resistance to ETV is detected in all PVRs receiving long-term ETV therapy.

Long-term follow-up and suboptimal treatment rates of treatment-eligible chronic hepatitis B patients in diverse practice settings: a gap in linkage to care

Background and aims

Despite available effective therapies, only a minority of patients with chronic hepatitis B (CHB) receive treatment. Our goal is to study treatment rates and time to treatment initiation in patients who meet treatment criteria on long-term follow-up.

Methods

We performed a retrospective cohort study of 608 consecutive treatment-eligible patients with CHB (by 2008 US Panel or 2009 American Association for the Study of Liver Disease (AASLD) criteria) at a US community gastroenterology clinic and a university liver clinic between 2007 and 2011. Patients were observed until they started treatment or last follow-up if untreated.

Results

Mean age was 44 and most were Asian (96%) with community patients being younger and having lower alanine aminotransferase (ALT) levels. A total of 62% started treatment, and 38% remained untreated after median follow-up of 17 months (IQR=1–40 months). Overall, treatment rate was significantly higher at university liver clinic than in the community (66.7% vs 59.9%, p=0.01). In multivariate analysis, older age (HR 1.02, p=0.002), male gender (HR 1.37, p=0.02), and baseline ALT >45 U/L for males and >29 U/L for females (HR 2.24, p<0.0001) were significant predictors of treatment initiation, but not practice setting.

Conclusions

Approximately 40% of treatment-eligible patients still have not started treatment on longer follow-up. Treatment rates were higher at university clinics, but practice setting was not a predictor for treatment, but older age, male gender, and higher ALT levels were. Further studies are needed to determine the barriers for treatment initiation and to improve treatment rates in treatment-eligible patients.

Efficacy of tenofovir disoproxil fumarate therapy in Chinese chronic hepatitis B patients after multiple antiviral failures

AIM

In this prospective study, we aimed to evaluate the efficacy and safety of tenofovir disoproxil fumarate (TDF) in Chinese chronic hepatitis B (CHB) patients after multiple nucleoside/nucleotide analog (NA) treatment failures.

METHODS

A total of 115 Chinese CHB patients with suboptimal response to two or more NA treatments were included in this study. All patients were changed to TDF (300 mg/day, oral administration) antiviral treatment for at least 72 weeks. Hepatitis B virus (HBV) polymerase (P) gene mutation screening for each patient was performed. In addition, virological, biochemical responses and estimated glomerular filtration rate (eGFR) of each patient at weeks 12, 24, 48 and 72 of TDF treatment were evaluated.

RESULTS

Seventy-six out of 115 patients had drug-resistance mutations (R(+) ), including 27 with adefovir (ADV)-associated mutations (35.5%) and 49 with lamivudine (LMV)-associated mutations (64.5%). For all included patients, complete viral response (CVR) of HBV DNA (<100 IU/mL) was 57.4%, 69.6%, 74.8% and 86.1% at weeks 12, 24, 48 and 72 of TDF treatment, respectively. Alanine aminotransferase normalization and hepatitis B e-antigen seroclearance occurred in 77.3% and 23.2%, respectively, after 72-week TDF treatment. CVR at weeks 12, 24 and 48 was observed more commonly in patients with baseline HBV DNA of less than 10(6)  IU/mL. There was no significant reduction of eGFR induced by the TDF treatment.

CONCLUSION

Seventy-two-week treatment with TDF in Chinese CHB patients with previously multiple NA treatment failures exhibited effective and safe outcomes, which were independent of baseline mutations conferring ADV or LMV resistance.

Durability of Nucleos(t)ide Analogues Treatment in Patients With Chronic Hepatitis B

Long-term nucleos(t)ide analogues (NUCs) treatment is usually required for patients with chronic hepatitis B (CHB). However, whether discontinuation of NUCs is possible in selected patients remains debated. The aim of this study was to assess the durability of NUCs and predictors of sustained response after cessation of NUCs.Ninety-three CHB patients (29 HBeAg-positive and 64 HBeAg-negative) from 2 medical centers in Taiwan with discontinuation of NUCs after a median of 3 years' treatment were retrospectively reviewed. Fifteen (51.7%) HBeAg-positive and 57 (89.1%) HBeAg-negative patients achieved APASL treatment endpoints. Virological relapse (VR) and clinical relapse (CR) were defined according to APASL guidelines.Achieving APASL endpoint was associated with longer median time to CR in HBeAg-positive patients, but not in HBeAg-negative cases. The cumulative 1-year VR and CR rates were 55.3% and 14.4% in HBeAg-positive patients, and 77.7% and 41.9% in HBeAg-negative patients, respectively. In HBeAg-negative patients, baseline HBV DNA >10 IU/mL was the only predictor of VR (hazard ratio [HR] = 2.277, P = 0.019) and CR (HR = 3.378, P = 0.014). HBsAg >200 IU/mL at the end of treatment (EOT) was associated with CR (HR = 3.573, P = 0.023) in patients developing VR. HBeAg-negative patients with low baseline viral loads and low HBsAg levels at EOT had minimal risk of CR after achieving APASL treatment endpoint (P = 0.016).The VR rate is high, but the risk of CR is low within 1 year with consolidation treatment after HBeAg seroconversion. Longer consolidation treatment to reduce the risk of VR should be considered in HBeAg-positive patients. As high risk of VR and CR, cessation of NUCs therapy could be considered only in selected HBeAg-negative patients.

Partial virological response to entecavir treatment in nucleos(t)ide-naïve patients with HBeAg-positive chronic hepatitis B is not caused by reduced sensitivity

Some patients with chronic hepatitis B (CHB) receiving entecavir (ETV) exhibit partial virological response (PVR) to ETV and the mechanism is not clear. In this study, we aim to investigate the in vitro susceptibility of residual clinical strains isolated from the sera of nucleos(t)ide-naïve hepatitis B virus e antigen (HBeAg)-positive patients with CHB and PVR to ETV, and to evaluate the clinical and virological responses to prolonged ETV monotherapy in these patients. We followed 69 nucleos(t)ide-naïve HBeAg-positive CHB patients receiving ETV treatment, with 13 partial responders to ETV. And we found that no genotypic resistance mutants were detected among the 13 PVR patients. Phenotypic analysis revealed that the residual HBV strains had normal replication capacity, and were as susceptible to ETV as wild-type HBV. All PVR patients continued to receive ETV monotherapy, and serum HBV DNA of the majority became undetectable after prolonged treatment. However, none of these patients achieved HBeAg loss. In contrast, 25.6% and 23.2% of the patients with virological response achieved HBeAg loss (P < 0.001) and HBeAg seroconversion (P < 0.001) at week 144, respectively. Thus, we conclude suboptimal response to ETV might not be due to reduced HBV susceptibility to ETV, and prolonging ETV monotherapy in patients with PVR is recommended.

Deep sequencing analysis of HBV genotype shift and correlation with antiviral efficiency during adefovir dipivoxil therapy

Background

Viral genotype shift in chronic hepatitis B (CHB) patients during antiviral therapy has been reported, but the underlying mechanism remains elusive.

Methods

38 CHB patients treated with ADV for one year were selected for studying genotype shift by both deep sequencing and Sanger sequencing method.

Results

Sanger sequencing method found that 7.9% patients showed mixed genotype before ADV therapy. In contrast, all 38 patients showed mixed genotype before ADV treatment by deep sequencing. 95.5% mixed genotype rate was also obtained from additional 200 treatment-naïve CHB patients. Of the 13 patients with genotype shift, the fraction of the minor genotype in 5 patients (38%) increased gradually during the course of ADV treatment. Furthermore, responses to ADV and HBeAg seroconversion were associated with the high rate of genotype shift, suggesting drug and immune pressure may be key factors to induce genotype shift. Interestingly, patients with genotype C had a significantly higher rate of genotype shift than genotype B. In genotype shift group, ADV treatment induced a marked enhancement of genotype B ratio accompanied by a reduction of genotype C ratio, suggesting genotype C may be more sensitive to ADV than genotype B. Moreover, patients with dominant genotype C may have a better therapeutic effect. Finally, genotype shifts was correlated with clinical improvement in terms of ALT.

Conclusions

Our findings provided a rational explanation for genotype shift among ADV-treated CHB patients. The genotype and genotype shift might be associated with antiviral efficiency.

Cost-effectiveness analysis of lamivudine, telbivudine, and entecavir in treatment of chronic hepatitis B with adefovir dipivoxil resistance

The purpose of this study was to analyze the cost-effectiveness of lamivudine (LMV), telbivudine (LdT), and entecavir (ETV) in treatment of chronic hepatitis B with adefovir dipivoxil (ADV) resistance. Two hundred and fifty-two patients were recruited and screened for resistance to ADV and randomly assigned into three groups: LMV + ADV, LdT + ADV, and ETV + ADV. The ratio of biochemical response, virological response, seroconversion of hepatitis Be antigen (HBeAg)/hepatitis Be antibody (HBeAb), viral breakthrough, and the cost and effectiveness of treatments were analyzed. A comparison of the results of the ratio of biochemical response, virological response and seroconversion of HBeAg/HBeAb, showed no statistical difference between the three groups, with the economic cost of LMV + ADV the lowest, LdT + ADV the middle, and ETV + ADV the highest. The side effects of the three plans are all rare and tolerable. LMV + ADV is the optimal rescue strategy, and LdT + ADV the alternative selection in the economically less developed regions, while ETV + ADV was used in the economically developed regions.

The hepatitis B virus ribonuclease H as a drug target

Chronic hepatitis B virus (HBV) infection is a leading cause of hepatitis, liver failure, and hepatocellular carcinoma. An outstanding vaccine is available; however, the number of infections remains high. Current anti-HBV treatments with interferon α and nucleos(t)ide analogs clear the infection in only a small minority of patients, and either induce serious side-effects or are of very long duration. HBV is a small, enveloped DNA virus that replicates by reverse transcription via an RNA intermediate. The HBV ribonuclease H (RNaseH) is essential for viral replication, but it has not been exploited as a drug target. Recent low-throughput screening of compound classes with anti-Human Immunodeficiency Virus RNaseH activity led to identification of HBV RNaseH inhibitors in three different chemical families that block HBV replication. These inhibitors are promising candidates for development into new anti-HBV drugs. The RNaseH inhibitors may help improve treatment efficacy enough to clear the virus from the liver when used in combination with existing anti-HBV drugs and/or with other novel inhibitors under development. 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."

Long-term efficacy of tenofovir disoproxil fumarate therapy after multiple nucleos(t)ide analogue failure in chronic hepatitis B patients

BACKGROUND/AIMS

The efficacy of tenofovir disoproxil fumarate (TDF) for the treatment of chronic hepatitis B (CHB) patients following prior treatment failure with multiple nucleos(t)ide analogues (NAs) is not well defined, especially in Asian populations. In this study we investigated the efficacy and safety of TDF rescue therapy in CHB patients after multiple NA treatment failure.

METHODS

The study retrospectively analyzed 52 CHB patients who experienced failure with two or more NAs and who were switched to regimens containing TDF. The efficacy and safety assessments included hepatitis B virus (HBV) DNA undetectability, hepatitis B envelop antigen (HBeAg) seroclearance, alanine transaminase (ALT) normalization and changes in serum creatinine and phosphorus levels.

RESULTS

The mean HBV DNA level at baseline was 5.4 ± 1.76 log10 IU/mL. At a median duration of 34.5 months of TDF treatment, the cumulative probabilities of achieving complete virological response (CVR) were 25.0%, 51.8%, 74.2%, and 96.7% at 6, 12, 24, and 48 months, respectively. HBeAg seroclearance occurred in seven of 48 patients (14.6%). ALT levels were normalized in 27 of 31 patients (87.1%) with elevated ALT at baseline. Lower levels of HBV DNA at baseline were significantly associated with increased CVR rates (p < 0.001). However, CVR rates did not differ between TDF monotherapy or combination therapy with other NAs, and were not affected by mutations associated with resistance to NAs. No significant adverse events were observed.

CONCLUSIONS

TDF is an efficient and safe rescue therapy for CHB patients after treatment failure with multiple NAs.

STING agonists induce an innate antiviral immune response against hepatitis B virus

Chronicity of hepatitis B virus (HBV) infection is due to the failure of a host to mount a sufficient immune response to clear the virus. The aim of this study was to identify small-molecular agonists of the pattern recognition receptor (PRR)-mediated innate immune response to control HBV infection. To achieve this goal, a coupled mouse macrophage and hepatocyte culture system mimicking the intrahepatic environment was established and used to screen small-molecular compounds that activate macrophages to produce cytokines, which in turn suppress HBV replication in a hepatocyte-derived stable cell line supporting HBV replication in a tetracycline-inducible manner. An agonist of the mouse stimulator of interferon (IFN) genes (STING), 5,6-dimethylxanthenone-4-acetic acid (DMXAA), was found to induce a robust cytokine response in macrophages that efficiently suppressed HBV replication in mouse hepatocytes by reducing the amount of cytoplasmic viral nucleocapsids. Profiling of cytokines induced by DMXAA and agonists of representative Toll-like receptors (TLRs) in mouse macrophages revealed that, unlike TLR agonists that induced a predominant inflammatory cytokine/chemokine response, the STING agonist induced a cytokine response dominated by type I IFNs. Moreover, as demonstrated in an HBV hydrodynamic mouse model, intraperitoneal administration of DMXAA significantly induced the expression of IFN-stimulated genes and reduced HBV DNA replication intermediates in the livers of mice. This study thus proves the concept that activation of the STING pathway induces an antiviral cytokine response against HBV and that the development of small-molecular human STING agonists as immunotherapeutic agents for treatment of chronic hepatitis B is warranted.

Therapeutic strategies for a functional cure of chronic hepatitis B virus infection

Treatment of chronic hepatitis B virus (HBV) infection with the viral DNA polymerase inhibitors or pegylated alpha-interferon has led to a significant retardation in HBV-related disease progression and reduction in mortality related to chronic hepatitis B associated liver decompensation and hepatocellular carcinoma. However, chronic HBV infection remains not cured. The reasons for the failure to eradicate HBV infection by long-term antiviral therapy are not completely understood. However, clinical studies suggest that the intrinsic stability of the nuclear form of viral genome, the covalently closed circular (ccc) DNA, sustained low level viral replication under antiviral therapy and homeostatic proliferation of hepatocytes are the critical virological and pathophysiological factors that affect the persistence and therapeutic outcomes of HBV infection. More importantly, despite potent suppression of HBV replication in livers of the treated patients, the dysfunction of HBV-specific antiviral immunity persists. The inability of the immune system to recognize cells harboring HBV infection and to cure or eliminate cells actively producing virus is the biggest challenge to finding a cure. Unraveling the complex virus–host interactions that lead to persistent infection should facilitate the rational design of antivirals and immunotherapeutics to cure chronic HBV infection.

HBsAg as an important predictor of HBeAg seroconversion following antiviral treatment for HBeAg-positive chronic hepatitis B patients

Background

Serum quantitative hepatitis B surface antigen (HBsAg) levels may be an important predictor of hepatitis B e antigen (HBeAg) seroconversion (SC) in HBeAg-positive chronic hepatitis B (CHB) patients during antiviral treatment. The pattern of HBsAg variation in CHB patients either with or without SC following tenofovir disoproxil fumarate (TDF) treatment is not clearly understood.

Methods

Twenty patients with full experimental data were enrolled, and liver biochemistry, serum HBV DNA, and circulating CD4⁺CD25⁺ regulatory T cell (Treg) levels were determined at baseline and every 12weeks after the initiation of TDF treatment (for a total of 96weeks). In addition, the relationship between HBsAg or HBeAg and alanine aminotransferase (ALT), HBV DNA and Treg levels in SC and non-SC patients was analyzed.

Results

In all, 9 patients had undergone HBeAg seroconversion by week 72 of TDF treatment, and biochemical and virological indexes and Treg percentages declined to normal levels. Furthermore, the positive correlation between HBsAg and ALT, HBV DNA and Treg levels was significant for SC patients, but not for non-SC patients. However, for HBeAg, significant positive correlations were or not observed for both SC and non-SC patients.

Conclusions

The quantitation of HBsAg is a more useful indicator than HBeAg for distinguishing SC and non-SC patients during TDF treatment. Moreover, HBsAg may be related to immune regulatory property of CHB patients during antiviral treatment.

The natural course of chronic hepatitis B virus infection and its management

Chronic infection with the hepatitis B virus (HBV) runs a long natural course during which underlying changes in liver histology can progress to cirrhosis and hepatic decompensation, as well as to hepatocellular carcinoma. Therapeutic intervention is currently aiming at suppression of HBV replication by applying a number of pharmacological agents. For an optimum use of available therapies, good knowledge of the natural course of chronic infection, as well as of the role played by several viral, host, and environmental factors, is mandatory. The larger part of this chapter deals with how to treat the various subsets of patients with chronic hepatitis B (CHB), using mainly three first-line drugs: pegylated interferon-α2a, entecavir, and tenofovir, administered either in finite courses or indefinitely. The frequency of virological, serological, biochemical, and histological responses in the various subsets of patients, both during and after stopping treatment, is reviewed. It is stressed that the application of the highly potent antivirals entecavir and tenofovir, with acceptable safety records and with a high barrier to HBV resistance, represents major progress in the treatment of CHB. Despite the hitherto important developments in the treatment of viral hepatitis B, clinical cure of chronic HBV infection with HBsAg loss is achievable only in a few treated patients while eradication of HBV infection appears unrealistic. Development of new pharmacological agents acting at multiple targets of the replicative cycle of HBV may achieve higher efficacy and even cure of CHB.

Identification of serum cytokine profiles associated with HBeAg seroconversion following antiviral treatment interruption

The major shortcoming of nucleos(t)ide analogue therapy for chronic hepatitis B (CHB) is the frequent requirement for indefinite therapy. Withdrawal of treatment can result in viral rebound with an alanine aminotransferase (ALT) flare leading to hepatic decompensation, while in others this can lead to hepatitis B e antigen (HBeAg) seroconversion. The aim of the study was to identify host immune profiles associated with these different outcomes. Eighteen HBeAg(+) patients, enrolled on a phase III trial with the nucleoside analogue adefovir dipivoxil, were followed for up to 128 weeks. For the first 48 weeks, all patients received continuous therapy. Subsequently, patients experienced cycles of treatment interruptions due to random drug/placebo misallocations. Host immune profiles were characterized by measuring a panel of serum cytokines before, during, and after each cycle of treatment withdrawal. Virus-specific T-cell responses were also determined at these time points in a subset of patients to elucidate the mechanisms utilized to control hepatitis B virus (HBV) replication post-treatment. Significantly, elevated levels of IFN-γ, IP-10, and IL-2 on-treatment were associated with HBeAg seroconversion after treatment withdrawal. In these patients, treatment interruption induced further increases in serum IFN-γ levels and marked increases in virus-specific T-cells producing IFN-γ, but minimal alterations in viremia and ALT. In HBeAg(+) patients with low on-treatment levels of serum IFN-γ, the interruption of therapy induced significant elevations in HBV-DNA, ALT, IP-10, and increases in virus-specific T-cells producing IL-10. Evaluating on-treatment serum cytokines in concert with virologic and clinical parameters may help to identify CHB patients who can successfully discontinue nucleos(t)ide analogue therapy.