96 weeks combination of adefovir dipivoxil plus emtricitabine vs. adefovir dipivoxil monotherapy in the treatment of chronic hepatitis B

Early Viral Kinetics with Telbivudine, Tenofovir or Combination of Both in Immunotolerant Patients with Hepatitis B e Antigen-Positive Chronic Hepatitis B

Introduction

Viral kinetics has proved useful in understanding antiviral potency, determining antiviral profiles and optimizing treatment strategy.

Methods

This was a randomized, open-label study comparing the viral kinetics in 46 hepatitis B e antigen-positive patients during 12-week treatment with telbivudine monotherapy, tenofovir monotherapy or the combination of telbivudine plus tenofovir. A standard biphasic mathematical model was used to compare hepatitis B virus (HBV) DNA decay parameters.

Results

Forty-six patients received telbivudine (n = 16), tenofovir (n = 14) or telbivudine plus tenofovir (n = 16). From baseline to Week 12, the mean (SD) reduction in HBV DNA levels was not significantly different between treatment groups: −3.9 (0.9) log₁₀ copies/mL in telbivudine group, −4.2 (0.7) log₁₀ copies/mL in tenofovir group, and −4.4 (1.0) log₁₀ copies/mL in combination group. No significant difference was observed among the three groups for viral clearance rate per day (0.97, 1.02, and 0.88, respectively) or for infected cell loss rate per day (0.04, 0.05, and 0.05, respectively). Antiviral efficiency in blocking viral production was similar in the monotherapy groups (median; 99.7% in telbivudine group and 99.4% in tenofovir group), but was slightly better and more homogeneous in the combination treatment group than in the monotherapy groups: mean (SD), 99.1% (0.8%) and 98.8% (1.6%), respectively (Wald–Wolfowitz test; P = 0.038). All treatments were well tolerated and no serious adverse event was reported during the study. Of the 46 patients in the safety population, 23 experienced adverse events. Most of the adverse events were not suspected to be related to the study drug by the investigators.

Conclusion

Monotherapy with telbivudine or tenofovir showed similar antiviral effectiveness in HBV DNA reduction and viral kinetics of HBV DNA decay. Efficiency in blocking viral production was slightly improved in the combination treatment group compared to the monotherapy groups.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0039-5) contains supplementary material, which is available to authorized users.

Chronic hepatitis B virus infection: epidemiology, prevention, and treatment in China

Chronic hepatitis B is a major health problem in China. The universal vaccination program since 1992 has changed the epidemiology of hepatitis B virus infection in China from highly to moderately endemic. The most prevalent hepatitis B virus strains in China are genotypes B and C, whereas those in western provinces are genotypes D and C/D hybrid. Chronic hepatitis B poses a heavy burden to the society in China. Different treatment strategies have been explored to improve patient outcomes in a cost-effective manner. However, antiviral drugs with a low genetic barrier to resistance are still extensively used because of the generally low income and limited resources in China. Individualized antiviral therapy is closely associated with translational medicine, which utilizes information from studies on genomics, immune biomarkers, and fibrosis. The results of these studies are crucial in further improving treatment outcomes.

Management of chronic hepatitis B: Canadian Association for the Study of the Liver consensus guidelines

Chronic hepatitis B (CHB) is a dynamic disease that is influenced by host and virological factors. The management of CHB has become more complex with the increasing use of long-term oral nucleos⁄tide analogue antiviral therapies and the availability of novel diagnostic assays. Furthermore, there is often a lack of robust data to guide optimal management such as the selection of therapy, duration of treatment, potential antiviral side effects and the treatment of special populations. In November 2011, the Canadian Liver Foundation and the Canadian Association for the Study of the Liver convened a consensus conference to review the literature and analyze published data, including other international expert guidelines on CHB management. The proceedings of the consensus conference are summarized and provide updated clinical practice guidelines to assist Canadian health care providers in the prevention, diagnosis, assessment and treatment of CHB.

Randomized trial of lamivudine, adefovir, and the combination in HBeAg-positive chronic hepatitis B

The aim of this study was to compare the efficacy of lamivudine or adefovir alone for 96 weeks versus initial treatment with the combination of lamivudine and adefovir for 12 to 24 weeks followed by adefovir alone. One hundred and fifty patients with HBeAg-positive chronic hepatitis B were randomized equally to lamivudine and adefovir diprivoxil combination therapy (LA), lamivudine alone (L), or adefovir dipivoxil alone (A) in a multicenter randomized clinical trial. In the LA group, the earliest time for lamivudine discontinuation was 12 weeks and adefovir monotherapy was continued until 96 weeks. Groups L and A received monotherapies for 96 weeks. At 12 weeks, the decrease in HBV DNA, percentage of patients with negative HBV DNA, and ALT normalization rate for the LA group were comparable to those of group L, but superior to those of group A. At 24 weeks, the rates of negative HBV DNA and HBeAg seroconversion of group LA were significantly higher than the monotherapy groups. This superiority was subsequently preserved during the maintenance phase with adefovir monotherapy. Starting at 48 weeks, the mean HBV DNA level of group L increased over the 24-week level. In contrast, the A group's rates of virological response, biochemical response, and HBeAg seroconversion continued to improve. At week 96, the percentage of patients with undetectable DNA and HBe seroconversion of LA group (100%, 51%) was higher than that of L (66%, 21%) and A group (49%, 33%), while no significant difference was observed between the L and A groups. During the course of therapy, no lamivudine- or adefovir-resistance mutations were discovered in the LA group. Rates of adverse reactions were comparable between the three groups. Combination therapy with lamivudine and adefovir for 12 to 24 weeks followed by adefovir monotherapy significantly improved antiviral efficacy and reduced drug resistance without compromising safety and tolerability compared to either drug alone in HBeAg-positive chronic hepatitis B.

KASL Clinical Practice Guidelines: Management of chronic hepatitis B

The guideline on the management of chronic hepatitis B (CHB) was first developed in 2004 and revised in 2007 by the Korean Association for the Study of the Liver (KASL). Since then there have been many developments, including the introduction of new antiviral agents and the publications of many novel research results from both Korea and other countries. In particular, a large amount of knowledge on antiviral resistance--which is a serious issue in Korea--has accumulated, which has led to new strategies being suggested. This prompted the new guideline discussed herein to be developed based on recent evidence and expert opinion.

TARGET POPULATION

The main targets of this guideline comprise patients who are newly diagnosed with CHB and those who are followed or treated for known CHB. This guideline is also intended to provide guidance for the management of patients under the following special circumstances: malignancy, transplantation, dialysis, coinfection with other viruses, pregnancy, and children.

Adefovir dipivoxil in chronic hepatitis B: history and current uses

INTRODUCTION

The nucleotide analogue adefovir dipivoxil (ADV) was approved in 2002 for the treatment of chronic infection with hepatitis B virus (HBV), in both hepatitis B e antigen (HBeAg)-positive and -negative patients. ADV 10 mg daily has been associated with improved liver histology, decreased levels of HBV DNA and alanine aminotransferase (ALT), and seroconversion of HBeAg.

AREAS COVERED

This paper reviews the use of ADV as a first-line treatment for chronic hepatitis B and as an add-on therapy in chronic HBV-infected patients with lamivudine resistance. In the years since its launch, clinical resistance to ADV has emerged, and tenofovir and entecavir have shown greater efficacy in reducing viral load.

EXPERT OPINION

Many patients who started antiviral therapy with ADV (either as monotherapy or in combination with lamivudine) remain on this agent because they have undetectable viremia, but its future use will probably diminish because of the availability of more potent drugs. ADV is generally well tolerated, though the 10 mg dose is associated with low risk of nephrotoxicity.

Randomised clinical trial: the benefit of combination therapy with adefovir and lamivudine for chronic hepatitis B

BACKGROUND

Combination antiviral therapy holds the promise of increasing response rates while decreasing antiviral resistance, but has yet to be shown to be beneficial or necessary in chronic hepatitis B.

AIM

To evaluate the benefit of combination therapy with adefovir and lamivudine versus adefovir alone in maintaining virological, biochemical and histological responses.

METHODS

Patients with chronic hepatitis B with and without previous lamivudine therapy were randomised to receive adefovir alone (10 mg/daily) or adefovir and lamivudine (100 mg/daily) for up to 192 weeks. Study endpoints were (i) maintained virological (HBV DNA <500 copies/mL), biochemical and histological response, (ii) loss of HBeAg and (iii) loss of HBsAg.

RESULTS

A total of 41 patients were enrolled, including 31 HBeAg -positive and 31 treatment-naïve subjects. 30 patients remained on assigned therapy at 192 weeks. The percentage of patients achieving a combined maintained response was higher in the combination than the monotherapy arm, both at week 48 (59% vs. 26%, P = 0.06) and 192 (68% vs. 31%, P = 0.03). At week 192, 76% of the combination vs. 36% of the monotherapy group had loss of HBeAg (P = 0.03). One patient receiving adefovir cleared HBsAg. Adefovir resistance developed in 6 of 19 (32%) monotherapy but none of 22 combination treated patients (P = 0.03).

CONCLUSIONS

Extended combination therapy with lamivudine and adefovir is associated with a high rate of long-term virological and biochemical response. Adefovir monotherapy appears to be less effective mainly because of poor initial response and the ultimate development of antiviral resistance (www.Clinical. Trials.gov NCT00023309).

Efficacy of peginterferon α-2a and predictors of response in HBeAg-negative, genotype D-naive patients

BACKGROUND

Peginterferon (PEG-IFN) α-2a has been shown to induce a sustained virologic response (SVR) in 20-30% of "hepatitis B e antigen (HBeAg)"-negative patients.

AIM

To determine the safety and efficacy of PEG-IFN α-2a in HBeAg-negative, genotype D-naive patients and to analyze the predictors of response.

METHODS

This prospective, multicenter, open-label, nonrandomized trial was conducted at four hospitals. A total of 35 consecutive HBeAg-negative naive genotype D patients received PEG-IFN α-2a for 48 weeks.

RESULTS

Based on a cutoff of hepatitis B virus (HBV) DNA <400 copies ml(-1), an early virologic response (EVR) at week 12, end of treatment virologic response (ETVR) at week 48, and SVR at week 72 were achieved by 3 (9%), 9 (26%), and 8 patients (23%), respectively. The EVR rate improved to 43%, ETVR to 49%, and SVR to 57%, when a HBV DNA cutoff level of <20,000 copies ml(-1) was used. Pretreatment HBsAg level was not a predictor for SVR on univariate analysis, but correlated with decline in HBV DNA levels at weeks 48 and 72. On multivariate logistic regression analysis, low body weight, high alanine aminotransferase (ALT), low HBV DNA, and low triglyceride levels were identified as baseline predictors of SVR.

CONCLUSION

HBeAg-negative genotype D-naive patients treated with PEG-IFN α-2a achieved SVR in 23 (HBV <400 copies ml(-1)) and 57% (HBV <20,000 copies ml(-1)) of patients, a better response than previously reported that might be related to the absence of drug resistance in these naive patients. Pretreatment predictors of SVR were low body weight, high ALT, low HBV DNA, and low triglycerides.

Drug safety evaluation of adefovir in HBV infection

INTRODUCTION

Several nucleos(t)ide analogs (NUC) are available for the management of patients with chronic hepatitis B (CHB). In most patients, NUC need to be administered on a long-term basis, thus increasing the risk of adverse effects. Adefovir dipivoxil (ADV), the first nucloeotide analog developed to treat CHB, may indeed cause nephrotoxicity.

AREAS COVERED

The pharmacokinetic mechanism of action, potential mechanism of renal damage and long-term safety profile of ADV in CHB patients have been reported. The current monitoring modalities, together with dosage adjustments, treatment of patients with ADV-related kidney impairment and the therapeutic algorithm in place at the authors' Liver Center are also summarized. Although, in short-term clinical trials, a daily dose of 10 mg of ADV was safe owing to a low rate of negligible nephrotoxic effects, the same dose may be associated with a usually reversible, proximal renal tubular toxicity as reflected by hypophosphatemia and elevated creatinine levels. Occasionally, Fanconi syndrome occurred in ADV-treated patients.

EXPERT OPINION

Renal function at baseline and during treatment should be carefully assessed in all patients receiving ADV to adjust the dose according to creatinine clearance, aimed to prevent or minimize nephrotoxicity.

Combination Therapy for Chronic Hepatitis B: Current Indications

Hepatitis B infection remains a major public health problem globally and in the United States, with significant use of healthcare resources. Several therapeutic agents active against viral and host targets are currently available for its treatment. The success of combination therapy in HIV infection, which has similarities to hepatitis B in both therapeutic targets and treatment options, stimulated studies on the efficacy and safety of various combinations of available drugs in the treatment of hepatitis B infection. In this review, we analyze the current role of combination therapy in chronic hepatitis B infection.

Serum hepatitis B surface antigen concentration correlates with HBV DNA level in patients with chronic hepatitis B

BACKGROUND

Serum HBV DNA level is crucial in the management of chronic hepatitis B (CHB); however, the assay is expensive and cannot be used widely. Therefore, we explored the possibility of hepatitis B surface antigen (HBsAg) quantification as a surrogate marker for HBV DNA level in CHB patients.

METHODS

A total of 289 CHB patients were enrolled, 251 were evaluated at baseline and 75 of them were also evaluated during anti-HBV treatment. Another 38 on-treatment patients were used for validation. Serum HBsAg titre was quantified by an immunoassay and HBV DNA level by a PCR-based method. Baseline and on-treatment data were analysed.

RESULTS

In parallel to log(10) HBV DNA, the log(10) HBsAg was high in both immune tolerance and immune clearance phases, and significantly decreased in the inactive carrier state and was again increased in the reactivation phase of the CHB infection. There was a positive correlation between log(10) HBsAg and log(10) HBV DNA, which was greater in patients with chronic hepatitis, hepatitis B e antigen-positivity, greater alanine aminotransferase or HBsAg levels at baseline and during pegylated interferon treatment. Log(10) HBsAg could predict log(10) HBV DNA independently. An HBsAg titre of >900 IU/ml at baseline or >1,500 IU/ml within the first year of treatment could predict an HBV DNA level of >20,000 IU/ml, especially in subgroups of chronic hepatitis with alanine aminotransferase levels >40 IU/l. The dynamics of HBsAg might also predict serial HBV DNA changes. In the validation group, 64% of patients with on-treatment HBV DNA levels >20,000 IU/ml could be correctly predicted.

CONCLUSIONS

Serum HBsAg concentration might serve as a surrogate marker of HBV DNA level in CHB patients.

[Analogs combination therapy in chronic hepatitis B: when and how?]

Hepatitis B virus (HBV) genomic variability is responsible for the complexity of the viral quasi-species and its evolution during the course of infection. The persistence of infected cells promotes the selection of drug-resistant strains. The development of nucleoside analogs without cross-resistance has provided a rationale for combination therapy. De novo combination, with low genetic barrier drugs, prevents the emergence of resistance in the short-term for drugs with a low genetic barrier and improves the control of infection. Long-term studies are needed to determine whether de novo combination is beneficial for analogs with a high genetic barrier as well. The add-on strategy is a standard in case of emergence of resistant mutants. This strategy needs to be implemented as early as possible before the virological breakthrough, especially if the viral suppression is sub-optimal. Clinical trials are mandatory in order to assess whether a) de novo combination is better than an early add-on strategy; and b) whether in case of sub-optimal viral suppression, an early add-on strategy is better in the long-term than a switch to a more potent drug with a high genetic barrier.

Review article: chronic hepatitis B - anti-viral or immunomodulatory therapy?

BACKGROUND

First-line treatment options for chronic hepatitis B (CHB) consist of nucleos(t)ide analogues with a high barrier to resistance (entecavir and tenofovir) or the immunomodulatory agent peginterferon (PEG-IFN). The optimal choice for individual patients remains controversial.

AIM

To review treatment options for CHB, with a focus on deciding between prolonged nucleos(t)ide analogue therapy or a finite course of PEG-IFN.

METHODS

A comprehensive literature search was undertaken.

RESULTS

Long-lasting, treatment-maintained suppression of hepatitis B virus (HBV) DNA without resistance is achievable in most patients by entecavir or tenofovir. A sustained off-treatment response is, however, unlikely and long-term therapy must be anticipated. PEG-IFN offers a higher rate of sustained response in a subgroup of patients, but is frequently complicated by side effects. Pre-treatment predictors of response, including HBV genotype, alanine aminotransferase and HBV DNA levels, aid in selecting patients for PEG-IFN therapy. Furthermore, on-treatment markers such as quantitative hepatitis B surface antigen may be applied to identify nonresponders early during the PEG-IFN treatment course, thereby preventing unnecessary treatment.

CONCLUSIONS

Both nucleos(t)ide analogues and PEG-IFN can be prescribed as first-line treatment options for CHB. However, PEG-IFN should only be considered for patients with a high chance of response based on pre-treatment and on-treatment factors.

Review of hepatitis B therapeutics

Currently, there are 7 approved therapies for chronic hepatitis B virus (HBV) infection, an increase from just 3 agents 5 years ago. This review will focus on the pharmacology, potency, and adverse events associated with immunomodulatory agents and nucleos(t)ide analogues, with an emphasis on targets of therapy within the HBV life cycle. We will also offer guidelines for the use of available anti-HBV agents and review the emerging challenges in hepatitis B management, including HBV drug resistance, its management, and the potential role of combination therapy.

Optimal strategy for antiviral therapy of chronic hepatitis B

Hepatitis B virus (HBV) infection can induce cirrhosis and liver cancer to result in death. There are a considerable number of HBV-infected people in China. Antiviral therapy is key to disease control. However, the curative effect of currently available antiviral drugs for chronic hepatitis B is not ideal. Antiviral therapy should be optimized to improve the efficacy and reduce the incidence of drug resistance. At present, optimal therapy strategy involves choosing a therapeutic scheme based on baseline characteristics of the patient and utilizing the roadmap concept to adjust treatment plan according to early virologic response.

European guideline for the management of hepatitis B and C virus infections, 2010

These are the guidelines on hepatitis B and C management for IUSTI/WHO in Europe, 2010. They describe the epidemiology, diagnosis, clinical features, treatment and prevention of hepatitis B and C with particular reference to sexual health clinical practice.

Hepatitis B in HIV: available treatment options and approach to therapy

In the past 5 years, three new drugs were approved for hepatitis B, bringing the total number of therapies to five nucleos(-t)ide analogues and two interferons. Some of these drugs are also active against HIV. As the complexity of hepatitis B treatment increases, it becomes important for practitioners to be familiar with the potency, resistance patterns, and response rates for each hepatitis B agent. In this article, the efficacy in HIV and the best regimens for coinfected patients are discussed for those needing treatment for both infections. A particular emphasis is placed on cross-resistance among hepatitis B drugs.

Effect of newer oral antiviral agents on future therapy of chronic hepatitis B

Long-term therapy with oral nucleoside/nucleotide analogues (NAs) is a favoured approach to the treatment of patients with chronic hepatitis B (CHB); however, all oral agents currently approved for the treatment of such patients are associated with some risk for drug resistance. This can lead to a rebound in HBV levels and, eventually, progressive liver disease. Combination therapy is one strategy that has the potential for enhanced antiviral effects and diminished or delayed resistance. The disadvantages of combination therapy include increased cost, the potential for drug interactions and increased toxicity. Additional therapeutic efficacy from combination therapy has not been demonstrated in clinical trials of HBV, and this approach might be less relevant now that potent NAs with excellent drug resistance profiles are available. However, it might be possible to identify subsets of patients (for example, those with extremely high viraemia or low baseline alanine aminotransferase levels) who derive added benefit from combination therapy. This review examines efficacy and resistance data for new low resistance oral NAs and clinical experience to date with de novo combination therapy in patients with CHB. The application of combination therapy in select populations of patients with CHB is also discussed.

Lessons from HIV therapy applied to viral hepatitis therapy: summary of a workshop

Therapies for hepatitis B virus (HBV) have continued to evolve, and new therapies for hepatitis C virus (HCV) will soon be available in clinical practice. These medications for hepatitis C will mark the first time that direct antivirals that target HCV functions have been used. When such drugs are used as single agents, previously existing mutants with reduced susceptibility to them are rapidly selected. The relationship between these drug-resistant mutants and "wild-type" virus is unclear, but resistant strains likely have the potential to maintain the progression of liver disease despite successful treatment of "wild-type" virus. Resistant HBV and now HCV are already a clinical problem. The same issue was recognized very early in the development of therapy against HIV, with azidothymidine-resistant mutants detected within the first weeks of therapy. Clinical investigation and a progressive understanding of the pathogenesis of the disease overcame this challenge and led to the substantial and durable benefits of antiretroviral therapy that are evident today. To bring experts from the fields of HIV and viral hepatitis virology and therapy together for interactive discussions about how to apply the lessons from HIV to the further development of viral hepatitis therapy, the American Association for the Study of Liver Diseases held a single-topic conference entitled "Viral Hepatitis Therapy: Lessons to be Learned From HIV" on 24-26 July 2008. This article summarizes that conference.

Avoiding and managing lamivudine resistance in chronic hepatitis B: current approaches and potential strategies including pegylated interferon

Since its approval for the treatment of chronic hepatitis B in 1998, lamivudine (LAM) has been used extensively throughout the world, because of its relatively low costs and favourable tolerability. However, clinical trials and cohort studies have demonstrated that a high rate of resistance to this drug develops and, as a result, it is no longer included as a first-line therapy in most current treatment guidelines. Nevertheless, because of its low cost, this drug continues to be used in many countries and the pool of patients who have developed resistance to LAM continues to increase. Thus, there is a clear need to develop coherent management strategies to treat such patients as well as limit the emergence of resistance in the first instance. The purpose of this review is to highlight the need to aim for long-term treatment success while limiting the emergence of drug resistance and its consequences for the future. In addition to add-on/switch strategies with other nucleos(t)ide analogs, currently available data suggest that interferon-based therapies, with their potential to induce a sustained response, are worthy of consideration not only for reducing de novo resistance but as an option for the management of those patients in whom drug resistance has already developed.

Combination of Lamivudine and adefovir therapy in HBeAg-positive chronic hepatitis B patients with poor response to adefovir monotherapy

At present, there is no consensus treatment for patients who have poor response to Adevofir dipivoxil (ADV) monotherapy and no ADV-associated mutation. The purpose of this study was to evaluate the effect of a new therapeutic strategy combining Lamivudine (LAM) and ADV in patients with HBeAg-positive chronic hepatitis B (CHB) and poor response to ADV monotherapy. Thirty-one patients with chronic hepatitis B with HBV DNA > or = 10(4) copies/mL after 48 weeks of ADV monotherapy were included and received ADV plus LAM for 24 weeks. Compared with ADV monotherapy, ADV + LAM had an improved response rate at weeks 12 and 24 - compared with baseline, the median decrease in HBV-DNA level at week 12 and 24 were 1.27 and 2.03 log respectively. The virological response (VR) rate (HBV-DNA level <10(3) copies/mL) was 6.5% and 35.5% at weeks 12 and 24, respectively; the biochemical response (BR) rate (normalization of alanine aminotransferase levels) was 67.8% and 100%, respectively; the HBeAg loss rate was 6.9% and 34.5%, respectively; and the seroconversion rate (from HBeAg to HBeAb) was 3.5% and 6.9% respectively. No ADV-associated mutation was detected at baseline. After combination therapy for 24 weeks, no LAM-resistant or ADV-resistant mutations were detected. Only one patient had a mild adverse reaction. In conclusion, optimization of therapy combining LAM and ADV may be a good choice for patients with hepatitis B who have a poor response to ADV monotherapy.

Monotherapy versus combination therapy for the treatment of chronic hepatitis B

BACKGROUND

Nucleos(t)ide analogues, active against hepatitis B polymerase, suppress viral replication and improve clinical outcome. However, the emergence of drug-resistant mutants can result in treatment failure.

OBJECTIVES

We describe how the choice of first-line therapy is critical to long-term treatment success.

METHODS

A review of current drug therapies is provided.

RESULTS/CONCLUSIONS

Monotherapy with early-generation drugs (lamivudine or adefovir) was associated with a high rate of viral drug resistance and combination therapy with these agents was shown to reduce the incidence of resistance. The latest-generation drugs (entecavir and tenofovir) are potent inhibitors of viral replication and, in treatment-naive subjects, viral resistance to entecavir is uncommon and is not yet reported to tenofovir. Therefore, monotherapy with either entecavir or tenofovir is the current preferred option in treatment-naive patients. Combination therapy is appropriate in those with drug-resistant HBV infection, where drug choice is guided by the viral drug-resistance genotype/phenotype. Although combination therapy has been advocated in other patient groups (e.g., those with decompensated cirrhosis and following liver transplantation), there are, as yet, no data to mandate the use of combination therapy in such patients and any perceived benefit must be weighed against increased cost and risk for toxicity.

Predictors of treatment response in chronic hepatitis B

The ultimate goal of treatment for chronic hepatitis B is to reduce liver-related complications and mortality. Sustained hepatitis B e antigen (HBeAg) seroconversion and hepatitis B surface antigen (HBsAg) clearance 6-12 months after stopping treatment are the short-term surrogate outcomes for interferon or peginterferon therapy. As most patients require long-term nucleos(t)ide analogue treatment, which also has the risk of drug resistance in the case of incomplete viral suppression, maintained hepatitis B virus (HBV) DNA suppression to an undetectable level is the appropriate surrogate outcome. Because no antiviral treatment is perfect, it is desirable for treatment response to be predicted and the treatment regimen modified accordingly. At baseline, high ALT and low HBV DNA levels can predict response to both (peg)interferon and nucleos(t)ide analogues. Genotype A HBV responds best to peginterferon but HBV genotype has no predictive value for nucleos(t)ide analogue treatment. HBV DNA is a good on-treatment predictor of response for nucleos(t)ide analogues but not for (peg)interferon. The data supporting the use of quantitative HBsAg and HBeAg to predict response to peginterferon is stronger than that for nucleos(t)ide analogues. In conclusion, predictors of response are useful to provide the most appropriate antiviral therapy to the most suitable patients, in order to achieve the best response and improve the clinical outcome of chronic hepatitis B patients.

Combination treatment in HBeAg-negative chronic hepatitis B

Chronic hepatitis B (CHB) represents an important public health problem. HBeAg-negative CHB is frequently associated with advanced liver disease and its prevalence is increasing. Monotherapy with either interferon (conventional or pegylated) or nucleoside/nucleotide analogues has its limitations. It has been suggested that a combination of these agents might increase antiviral efficacy. However, existing data do not support this hypothesis, even though combination treatment appears to reduce the risk for emergence of lamivudine resistance. Nevertheless, most existing combination studies are small, and it is possible that they have not been designed to detect significant differences between combination treatment and monotherapies. Another limitation of these studies is that, in most of them, lamivudine treatment was discontinued after 1 year, a strategy that is not followed in clinical practice. It was thought to be interesting to evaluate the combination of a short course of interferon (particularly pegylated) with the long-term administration of nucleotide or nucleoside analogues. The efficacy of combining pegylated interferon with the newer nucleotide or nucleoside analogues or of nucleotide with nucleoside analogues could also be evaluated. However, findings show that until more data are available, combination therapy cannot be recommended as first-line treatment in patients with CHB. On the other hand, add-on therapy with adefovir or tenofovir is the treatment of choice in patients who develop resistance to lamivudine. In patients with cirrhosis, a combination of lamivudine/adefovir may also be used as initial treatment; another option would be to add tenofovir in patients with an insufficient response to entecavir.

Chronic Hepatitis B Infection: Principles of Therapy

Chronic hepatitis B is a global health concern in many resource-limited settings due to perinatal or pediatric hepatitis B virus transmission. In the United States, pediatric infection has been virtually eliminated due to maternal screening during pregnancy and the availability of an effective vaccine. However, young adults remain an at-risk group for hepatitis B virus infection due to sexual transmission and injection drug use. The frequency of progression from acute hepatitis B virus infection to chronic hepatitis B infection depends on multiple factors, including host immune function and age at time of hepatitis B virus infection. Fortunately, there are 7 currently approved therapies for chronic hepatitis B infection, and several emerging therapies that show promise. Despite the availability of these agents, many clinical questions still surround chronic hepatitis B therapy including when to start therapy, which agent is ideal for first and second line therapy, the appropriate duration of therapy, and the role of combination antiviral therapy. This review focuses on agents available for chronic hepatitis B management, including pharmacology, safety and efficacy data, monitoring parameters, and the role for each in chronic hepatitis B therapy in adult patients.

Prevention and management of drug resistance for antihepatitis B treatment

Emergence of drug resistance in antiviral therapy for chronic hepatitis B negates treatment benefits. There is a lower chance for emergence of resistance for drugs with rapid and potent viral suppression and a high genetic barrier for resistant mutations. Measurement of viral load at 24 weeks' treatment to aid decision making is mandatory for patients receiving drugs that are associated with a higher resistance rate. Combination treatment with drugs that belong to different groups is associated with a lower chance of resistance. To ensure better control of viral replication in patients with drug resistance, the addition of another drug without an overlapping resistance profile should be given as early as possible, preferably at the time when genotypic resistance emerges. With such strategies, most patients can be maintained in clinical remission. However, because of the mechanism of viral persistence, research efforts should continue to anticipate and prevent the emergence of multidrug-resistant strains.

Side effects of long-term oral antiviral therapy for hepatitis B

The aim of this review is to summarize the safety profile of the five approved oral nucleoside analogs used to treat chronic hepatitis B virus (HBV) infection, focusing on both the class adverse effects and those that have been reported with individual agents, as well as their safety in pregnancy. All nucleoside analogs have a "Black Box" warning because of their potential for inhibition of human DNA polymerase gamma involved in mitochondrial DNA replication. A reduction in intracellular mitochondrial DNA levels can lead to varying clinical manifestations of mitochondrial toxicity (i.e., neuropathy, myopathy, lactic acidosis), but these side effects are rarely reported with the oral antiviral agents active against HBV. Adefovir and tenofovir are associated with a dose-dependent but usually reversible proximal renal tubular toxicity. For these reasons, patients receiving these agents should be monitored for renal toxicity and the dose modified for renal insufficiency. Prolonged use of tenofovir has also been reported to lead to reduced bone mineral density in patients with human immunodeficiency virus infection, but prospective studies in patients with HBV infection are lacking. Telbivudine treatment is associated with moderate serum creatine phosphokinase elevations in up to 12% of patients. There have been few prospective studies on the safety of nucleoside analogs during pregnancy. According to the Antiretroviral Pregnancy Registry, the incidence of birth defects associated with lamivudine and tenofovir use during pregnancy is not increased. Studies on the safety of long-term therapy with the nucleoside analogs, alone and in combination, are needed as are further studies of children, the elderly, pregnant women, and patients with renal insufficiency.

Benefits and risks of combination therapy for hepatitis B

In successful antiviral therapy of hepatitis B, drug combinations, particularly combinations without cross-resistance, can delay or prevent the emergence of drug-resistant mutants. Because drug-resistant mutants are archived and may limit future therapeutic options, prevention is important for long-term therapeutic efficacy. Additionally, combining drugs may achieve synergistic or additive antiviral effects compared with single drug therapy. Undesirable aspects of combination therapy include higher treatment costs and possibly lower adherence rates (due to pill number or complexity of regimen). Potentially harmful effects of combination therapy include higher rates of side effects, reduced efficacy due to drug competition, and the risk of multidrug-resistant hepatitis B virus (HBV) if combination therapy is insufficient to prevent resistance. Combination therapy has been shown to reduce the rate of drug resistance in chronic hepatitis B, but only when drugs with a low barrier to resistance are used (lamivudine, adefovir). Combination therapies may achieve greater degrees of HBV DNA suppression, but this has not been associated with higher rates of seroconversion (hepatitis B e antigen or hepatitis B surface antigen) compared to single drug therapy. The benefit of combination therapy has yet to be demonstrated with agents that are associated with a high barrier to resistance (tenofovir, entecavir). The use of combination therapy is recommended in specific patient groups: those with decompensated cirrhosis, those coinfected with human immunodeficiency virus and HBV who are on antiretroviral therapy, those who have undergone liver transplantation, and those with drug-resistant HBV infection. There is insufficient evidence to recommend combination therapy as first-line therapy for all patients with chronic hepatitis B.

Viral dynamics of hepatitis B virus DNA in human immunodeficiency virus-1-hepatitis B virus coinfected individuals: similar effectiveness of lamivudine, tenofovir, or combination therapy

Following treatment of hepatitis B virus (HBV) infection with nucleos(t)ide reverse transcriptase inhibitors (NRTIs), there is a biphasic clearance of HBV, similar to that seen following treatment of human immunodeficiency virus-1 (HIV-1) and hepatitis C virus. Little is known about the impact of combination NRTIs and HIV-1 coinfection on HBV viral kinetic parameters following the initiation of HBV-active highly active antiretroviral therapy (HAART). HIV-1-HBV coinfected patients (n = 21) were enrolled in a viral kinetics substudy of the Tenofovir in HIV-1-HBV Coinfection study (TICO). TICO was a randomized (1:1:1) trial of tenofovir disoproxil fumarate (TDF, 300 mg) versus lamivudine (LMV, 300 mg) versus TDF/LMV within an efavirenz based HAART regimen initiated in HIV-1-HBV coinfected antiretroviral naïve individuals in Thailand. HBV DNA was measured frequently over the first 56 days. To fit the viral load data, we used a model of HBV kinetics that allows the estimation of treatment effectiveness, viral clearance and infected cell loss. We observed a biphasic decline in HBV DNA in almost all patients. We did not observe any significant differences in HBV viral dynamic parameters between the three treatments groups. Overall, median (interquartile range) HBV treatment effectiveness was 98% (95%-99%), median HBV virion half-life was 1.2 days (0.5-1.4 days), and median infected cell half-life was 7.9 days (6.3-11.0 days). When we compared hepatitis B e antigen (HBeAg)-positive and HBeAg-negative individuals, we found a significantly longer infected cell half-life in HBeAg-positive individuals (6.2 versus 9.0 days, P = 0.02).

CONCLUSION

HBV viral dynamic parameters are similar following anti-HBV NRTI monotherapy and dual combination therapy in the setting of HIV-1-HBV coinfection. HIV-1 coinfection has minimal effect on HBV viral dynamics, even in the setting of advanced HIV-1-related immunosuppression.

Hepatitis B virus infection in US correctional facilities: a review of diagnosis, management, and public health implications

Among the blood-borne chronic viral infections, hepatitis B virus (HBV) infection is one that is not only treatable but also preventable by provision of vaccination. Despite the availability of HBV vaccine for the last 15 years, more than 1.25 million individuals in the USA have chronic HBV infection, and about 5,000 die each year from HBV-related complications. From a societal perspective, access to treatment of chronic viral infections, like HIV and viral hepatitis, is highly cost-effective and has lasting benefits by reducing risk behaviors, morbidity, mortality, as well as disease transmission in the community. Individuals in correctional facilities are specially predisposed to such chronic viral infections because of their high-risk behaviors. The explosion of incarceration in the USA over the last few decades and the disproportionate burden of morbidity and mortality from chronic infections among the incarcerated have put incredible strains on an overcrowded system that was not originally designed to provide comprehensive medical care for chronic illnesses. Recently, there has been a call to address medical care for individuals with chronic medical conditions in correctional settings, including those with infectious diseases. The economic and public health burden of chronic hepatitis B and its sequelae, including cirrhosis and hepatocellular carcinoma, is felt most prominently in managed care settings with limited budgets, like correctional facilities. Prevalence of HBV infection among the incarcerated in the USA is fivefold that of the general population. We present a review of diagnosis, prevention, and the recently streamlined treatment guidelines for management of HBV infection in correctional settings, and discuss the implications and public health impact of these measures.

Role of combination therapy in chronic hepatitis B

Combination therapy includes the use of two or more antivirals for the treatment of chronic hepatitis B. No study has shown that combination therapy is superior to monotherapy in naive patients for achieving treatment end points, but combination appears to result in a lower incidence of resistance. Moreover, the higher-potency compounds have not yet been studied. Consideration should be given to treating lamivudine-resistant patients with combination therapy, preferably with a nucleotide analogue in conjunction with a nucleoside analogue. Combination therapy should be considered in patients with decompensated cirrhosis who are unable to achieve an undetectable viral level on monotherapy and in naive patients who still have a detectable viral level 6 to 12 months after starting therapy.

On-Treatment Outcome Prediction and Adjustment during Chronic Hepatitis B Therapy: Now and Future

Studies published to date regarding on-treatment outcome prediction during chronic hepatitis B therapy were reviewed. Studies have shown that initial virological responses in terms of week 24 serum hepatitis B virus (HBV) DNA levels are associated with therapeutic outcomes of 1-year pegylated interferon-α and entecavir therapy, and weeks 52 or 104 of lamivudine and telbuvudine therapy. HBV DNA levels at week 48 are also associated with long-term adefovir therapy outcomes. Conceptual on-treatment adjustment and strategies have been proposed; however, this approach seems only necessary during therapy with nucleos(t)ide analogues with substantial risk of drug resistance. In addition, studies are needed to decide whether switching to or adding on a second drug, and with which drug, is the most cost-effective strategy.

Management and prevention of drug resistance in chronic hepatitis B

The management of hepatitis B virus resistance to antivirals has evolved rapidly in recent years. The definition of resistance is now well established, with the importance of partial response and the improvement of assays to detect genotypic resistance and virological breakthrough. Data on phenotypic resistance have allowed to define the cross-resistance profile for the main resistant mutants, providing a rationale for treatment adaptation. Clinical studies have shown that an early treatment intervention in case of a virological breakthrough or a partial response with the addition of a second drug having a complementary cross-resistance profile allows one to maintain the majority of patients in clinical remission. The prevention of resistance should rely on the use of the most potent antivirals with a high genetic barrier to resistance as a first-line therapy. The future perspectives are to design strategies to hasten the HBsAg clearance, which should become a new treatment endpoint, to prevent drug resistance and to decrease the incidence of complications of chronic hepatitis B.

A treatment algorithm for the management of chronic hepatitis B virus infection in the United States: 2008 update

Chronic HBV infection is an important public health problem worldwide and in the United States. A treatment algorithm for the management of this disease, published previously by a panel of U.S. hepatologists, has been revised on the basis of new developments in the understanding of the disorder, the availability of more sensitive molecular diagnostic tests, and the licensure of new therapies. In addition, a better understanding of the advantages and disadvantages of new treatments has led to the development of strategies for reducing the rate of resistance associated with oral agents and optimizing treatment outcomes. This updated algorithm was based primarily on available evidence by using a systematic review of the literature. Where data were lacking, the panel relied on clinical experience and consensus expert opinion. The primary aim of antiviral therapy is durable suppression of serum HBV DNA to low or undetectable levels. Assays can now detect serum HBV DNA at levels as low as 10 IU/mL and should be used to establish a baseline level, monitor response to antiviral therapy, and survey for the development of drug resistance. Interferon alfa-2b, lamivudine, adefovir, entecavir, peginterferon alfa-2a, telbivudine, and tenofovir are approved as initial therapy for chronic hepatitis B and have certain advantages and disadvantages. Although all of these agents can be used in selected patients, the preferred first-line treatment choices are entecavir, peginterferon alfa-2a, and tenofovir. Issues for consideration for therapy include efficacy, safety, rate of resistance, method of administration, and cost.

Telbivudine, a nucleoside analog inhibitor of HBV polymerase, has a different in vitro cross-resistance profile than the nucleotide analog inhibitors adefovir and tenofovir

Telbivudine, a nucleoside analog inhibitor of the viral polymerase of hepatitis B virus (HBV), has been approved for the treatment of chronic HBV infection, along with the nucleoside inhibitors lamivudine and entecavir, and the nucleotide inhibitors adefovir and tenofovir. The resistance profiles of these agents were investigated via drug treatment of HepG2 cells stably transfected with wild-type or mutant HBV genomes bearing known resistance mutations. Telbivudine was not active against HBV strains bearing lamivudine mutations L180M/M204V/I but remained active against the M204V single mutant in vitro, potentially explaining the difference in resistance profiles between telbivudine and lamivudine. Against HBV genomes with known telbivudine-resistance mutations, M204I and L80I/M204I, telbivudine, lamivudine and entecavir lost 353- to >1000-fold activity whereas adefovir and tenofovir exhibited no more than 3-5-fold change. Conversely, against HBV cell lines expressing adefovir resistance mutations N236T and A181V, or the A194T mutant associated with resistance to tenofovir, telbivudine remained active as shown by respective fold-changes of 0.5 (N236T) and 1.0 (A181V and A194T). These in vitro results indicate that nucleoside and nucleotide drugs have different cross-resistance profiles. The addition of telbivudine to ongoing adefovir therapy could provide effective antiviral therapy to patients who develop adefovir resistance.

[Combination therapy in chronic hepatitis B]

The HBV genome variability is responsible for the complexitiy of the viral quasi-species and its evolution during the course of the infection. During antiviral therapy, the persistence of infected cells is another important determinant involved in the selection of drug resistant strains. The development of nucleoside analogs with complementary resistance profiles has provided the rationale for add-on strategies in case of virologic breakthrough. The current trend is to add antivirals earlier, before the rebound of viral load, especially in case of partial virologic response. Clinical trials are required to determine if a de novo combination of nucleoside analogs provides an added benefit compared to an early add-on strategy. However, de novo combination is recommended in patients whose liver functions cannot tolerate treatment failure, and in patients with a high risk of developing viral resistance because of a complex viral quasi-species prior to therapy.

Understanding the molecular basis of HBV drug resistance by molecular modeling

Despite the significant successes in the area of anti-HBV agents, resistance and cross-resistance against available therapeutics are the major hurdles in drug discovery. The present investigation is to understand the molecular basis of drug resistance conferred by the B and C domain mutations of HBV-polymerase on the binding affinity of five anti-HBV agents [lamivudine (3TC, 1), adefovir (ADV, 2), entecavir (ETV, 3), telbivudine (LdT, 4) and clevudine (l-FMAU, 5)]. In this regard, homology modeled structure of HBV-polymerase was used for minimization, conformational search and induced fit docking followed by binding energy calculation on wild-type as well as on mutant HBV-polymerases (L180M, M204V, M204I, L180M+M204V, L180M-M204I). Our studies suggest a significant correlation between the fold resistances and the binding affinity of anti-HBV nucleosides. The binding mode studies reveals that the domain C residue M204 is closely associated with sugar/pseudosugar ring positioning in the active site. The positioning of oxathiolane ring of 3TC (1) is plausible due the induced fit orientation of the M204 residue in wild-type, and further mutation of M204 to V204 or I204 reduces the final binding affinity which leads to the drug resistance. The domain B residue L180 is not directly close ( approximately 6A) to the nucleoside/nucleoside analogs, but indirectly associated with other active-site hydrophobic residues such as A87, F88, P177 and M204. These five hydrophobic residues can directly affect on the incoming nucleoside analogs in terms of its association and interaction that can alter the final binding affinity. There was no sugar ring shifting observed in the case of adefovir (2) and entecavir (3), and the position of sugar ring of 2 and 3 is found similar to the sugar position of natural substrate dATP and dGTP, respectively. The exocyclic double bond of entecavir (3) occupied in the backside hydrophobic pocket (made by residues A87, F88, P177, L180 and M204), which enhances the overall binding affinity. The active site binding of LdT (4) and l-FMAU (5) showed backward shifting along with upward movement without enforcing M204 residue and this significant different binding mode makes these molecules as polymerase inhibitors, without being incorporated into the growing HBV-DNA chain. Structural results conferred by these l- and d-nucleosides, explored the molecular basis of drug resistance which can be utilized for future anti-HBV drug discovery.

Hepatitis B: reflections on the current approach to antiviral therapy

This article summarizes the current state of antiviral therapy of hepatitis B with special attention given to areas that remain controversial or poorly defined. Strict adherence to liver association practice guidelines may result in missed opportunities to treat patients with significant underlying liver disease. In particular, recommended ALT thresholds may not appropriately reflect disease activity or degree of fibrosis. There is growing evidence that an alternative treatment paradigm for preventing late-stage disease complications may be indicated in highly viremic patients with early life exposure to hepatitis B. Pegylated interferon therapy is often a better choice for young to middle-aged patients with genotype A and B because of the higher rate of HBeAg seroconversion and a greater chance for HBsAg seroconversion in both HBeAg-positive and -negative patients as compared to nucleoside analogs. Nucleoside analog monotherapy is the current standard of care for many patients. However, long-term monotherapy results in resistance to a variable degree and sequential monotherapy may result in multi-drug resistant virus. Which patients would specifically benefit from early combination therapy also remains poorly defined. The rapidity and robustness of the suppression of HBV DNA while on a nucleoside analog should be monitored relatively early during treatment because it affects treatment outcome and the rate of resistance. While great progress has been made in treating hepatitis B, many important issues require further study.

Systematic review: combination therapies for treatment-naïve chronic hepatitis B

BACKGROUND

There is a renewed interest in use of combination therapies in treatment-naïve chronic hepatitis B (CHB) because of limitations of monotherapies.

AIM

To discuss the current status of combination therapies in treatment-naïve CHB.

METHODS

PubMed search was done using 'combination', 'sequential' and 'chronic hepatitis B' as the search terms.

RESULTS

The two most popular combination therapies include 'combination of nucleos(t)ide analogues' and 'combination of interferons and nucleos(t)ide analogues'. Combination therapies using two nucleos(t)ide analogues do not lead to higher long-term efficacy. However, addition of a nucleos(t)ide analogue with a good resistance profile to a nucleos(t)ide analogue with a lower genetic barrier to resistance decreases the risk of emergent resistance to the latter. Greater sustained virological, biochemical and seroconversion rates are observed with addition of lamivudine to conventional interferon, but pegylated-interferon monotherapy is equally effective as combination with lamivudine. Again, resistance to lamivudine is lower with its combination with interferons.

CONCLUSIONS

The answer to the question whether hepatitis B can be treated better with combination or monotherapy remains largely unknown. Additional trials are warranted of combination therapies of peginterferon and potent nucleos(t)ide analogues or therapies with the combined use of nucleos(t)ide analogues or immunomodulators.