Significance of HBV DNA levels at 12 weeks of telbivudine treatment and the 3 years treatment outcome

Chronic hepatitis B: New potential therapeutic drugs target

Chronic hepatitis B (CHB) infection remains the most causative agent of liver-related morbidity and mortality worldwide. It impacts nearly 300 million people. The current treatment for chronic infection with the hepatitis B virus (HBV) is complex and lacks a durable treatment response, especially hepatitis B surface antigen (HBsAg) loss, necessitating indefinite treatment in most CHB patients due to the persistence of HBV covalently closed circular DNA (cccDNA). New drugs that target distinct steps of the HBV life cycle have been investigated, which comprise inhibiting the entry of HBV into hepatocytes, disrupting or silencing HBV cccDNA, modulating nucleocapsid assembly, interfering HBV transcription, and inhibiting HBsAg release. The achievement of a functional cure or sustained HBsAg loss in CHB patients represents the following approach towards HBV eradication. This review will explore the up-to-date advances in the development of new direct-acting anti-HBV drugs. Hopefully, with the combination of the current antiviral drugs and the newly developed direct-acting antiviral drugs targeting the different steps of the HBV life cycle, the ultimate eradication of CHB infection will soon be achieved.

Hepatitis B Virus Infection: Overview

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

Present and Future Therapies for Chronic Hepatitis B

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

The impact of currently licensed therapies on viral and immune responses in chronic hepatitis B: Considerations for future novel therapeutics

Despite the availability of a preventative vaccine, chronic hepatitis B (CHB) remains a global healthcare challenge with the risk of disease progression due to cirrhosis and hepatocellular carcinoma. Although current treatment strategies, interferon and nucleos(t)ide analogues have contributed to reducing morbidity and mortality related to CHB, these therapies are limited in providing functional cure. The treatment paradigm in CHB is rapidly evolving with a number of new agents in the developmental pipeline. However, until novel agents with functional cure capability are available in the clinical setting, there is a pressing need to optimize currently licensed therapies. Here, we discuss current agents used alone and/or in combination strategies along with the impact of these therapies on viral and immune responses. Novel treatment strategies are outlined, and the potential role of current therapies in the employment of pipeline agents is discussed.

Engineered Janus probes modulate nucleic acid amplification to expand the dynamic range for direct detection of viral genomes in one microliter crude serum samples

The viral genome load in diverse clinical samples varies over several orders of magnitude (e.g. 1-104 copies per μL), thus a dynamic range-extended and sensitive analysis method is highly desired. However, existing well-developed nucleic acid amplification systems always suffer from either a limited dynamic range or modest sensitivity for analysis of these samples. Herein, we propose a general engineered Janus probe to modulate the thermodynamics and kinetic properties of the amplification reaction. Through rational regulation, the Janus system improves the performance by both reducing the background and enhancing the signal, expanding the operative dynamic range by 2 orders of magnitude. This proposed approach achieves a detection limit for hepatitis B virus (HBV) DNA of down to 3 copies and can be successfully applied for direct quantification of the HBV genome in one microliter crude serum samples without any pretreatment. The results are consistent with clinical diagnosis and hold considerable potential to discriminate healthy volunteers and patients at different disease stages. Whereas, following the same operation, the representative well-developed system provided serious false-negative results using such trace amounts of samples from clinically confirmed positive patients.

Telbivudine vs tenofovir in hepatitis B e antigen-negative chronic hepatitis B patients: OPTIMA roadmap study

AIM

To make efficacy and safety comparison of telbivudine-raodmap and tenofovir-roadmap in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) patients.

METHODS

This was the first prospective, randomised, two-arm, open-label, non-inferiority study in HBeAg-negative CHB patients that compared telbivudine and tenofovir administered as per roadmap concept. Patients were treated up to 24 wk and, depending on virologic response, continued the same therapy or received add-on therapy up to 104 wk. Eligible patients received an additional 52 wk of treatment in the extension period (i.e., up to 156 wk). Patients who developed virologic breakthrough (VB) while on monotherapy also received add-on therapy. The primary efficacy endpoint was the rate of patients achieving hepatitis B virus (HBV) DNA < 300 copies/mL at week 52. Secondary efficacy endpoints included the rates of HBV DNA < 300 and < 169 copies/mL, HBV DNA change from baseline, alanine aminotransferase normalisation, hepatitis B surface antigen (HBsAg) loss, HBsAg seroconversion, VB, and emergence of resistance at various timepoints throughout the study. Safety and estimated glomerular filtration rate (eGFR) were also analysed.

RESULTS

A total of 241 patients were randomised. Non-inferiority of telbivudine arm to tenofovir arm was demonstrated at week 52 (± 7 d window), with over 91% of patients in each treatment arm achieving HBV DNA level < 300 copies/mL. Both arms were similar in terms of key secondary efficacy variables at weeks 104 and 156. The percentage of patients achieving HBV DNA < 300 copies/mL remained high and was similar in the telbivudine and tenofovir arms at both weeks 104 and 156. Over 82% of patients in both arms achieved alanine aminotransferase normalisation at week 52, and this percentage remained high at weeks 104 and 156. Telbivudine treatment progressively reduced serum HBsAg levels from baseline while no change was reported in quantitative HBsAg during therapy with tenofovir. Both treaments showed acceptable safety profiles. The telbivudine arm showed eGFR improvement unlike the tenofovir arm.

CONCLUSION

Efficacy was shown for both telbivudine-roadmap and tenofovir-roadmap regimens in HBeAg-negative CHB patients over 156 wk. Telbivudine arm was associated with renal improvement.

Cost-effectiveness analysis of antiviral therapies for hepatitis B e antigen-positive chronic hepatitis B patients in China

BACKGROUND AND OBJECTIVE

Several antiviral therapies are now available for patients with chronic hepatitis B (CHB), but the most cost-effective strategy for Chinese patients is unclear. The aim of this study was to estimate the long-term cost effectiveness of the antiviral treatments (lamivudine, adefovir, telbivudine and entecavir) for hepatitis B e antigen (HBeAg)-positive CHB patients in China.

METHODS

A Markov model was used to simulate the life-time (41-year time span) costs and effectiveness associated with antiviral treatments from the perspective of Chinese healthcare. Relative model parameters were derived from Chinese population studies. Costs and effectiveness were discounted at 5 %. The highest retail prices for generic and branded drug prices were also considered. Probabilistic sensitivity analysis and one-way sensitivity analysis were used to explore model uncertainties.

RESULTS

In the base-case analysis, the least quality-adjusted life years (QALYs) were obtained with adefovir as the reference strategy. Lamivudine generated the highest incremental cost-effectiveness ratio (ICER), with an additional US$35,000 needed to gain one additional QALY for generic drugs and US$36,000 for branded drugs. Entecavir had the lowest ICER of US$7,600 and US$9,100, respectively. The projected 10-year cumulative incidences of compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma (HCC) and mortality for entecavir were lower than the other strategies. In probabilistic sensitivity analyses, entecavir was the preferred option at a threshold of US$18,924 per QALY.

CONCLUSIONS

In patients with HBeAg-positive CHB in China, entecavir is a cost-effective option compared with other therapies for CHB.

Involvement of soluble scavenger receptor A in suppression of T cell activation in patients with chronic hepatitis B

BACKGROUND

Scavenger receptor A (SRA) is expressed predominantly in phagocytic cells playing an essential role in the host immune defense against invading microorganisms. Our previous study reported the presence of SRA in a soluble form in patients with infection of hepatitis B viruses (HBV). However, the association of soluble SRA with stages of HBV infection and the immune response induced by HBV is not fully determined.

METHODS

In this study, we detected soluble SRA in serum from 29 chronic hepatitis B (CHB) patients, 28 chronic HBV carriers in the immune tolerant (IT) stage, 33 in the HBeAg-negative inactive carrier (IC) stage, and 22 healthy controls (HCs), respectively. We further analyzed the correlation of detected soluble SRA to inflammation and serum viral load. In addition, we investigated the regulatory role of soluble SRA in T cell activation, especially in CD8(+) T cell response to HBV peptide.

RESULTS

We demonstrated that Median levels of serum soluble SRA in CHB and IT patients were significantly higher than those of IC patients and HCs. Additionally, the concentrations of soluble SRA were negatively correlated with alanine transaminase levels in CHB patients. We also found that serum concentration of SRA was decreased during telbivudine treatment. Expressed SRA extracellular domain suppressed HBV core peptide-stimulated interferon-γ and tumor necrosis factor-α production in CD8(+) T cells, and it bound to T cells in a higher frequency in CHB patients than in HCs. Furthermore, we observed that naïve human T cells stimulated by anti-CD3 and CD28 antibodies in the presence of the recombinant SRA protein had reduced activation and proliferation.

CONCLUSION

In summary, we determined the level of soluble SRA in different stages of CHB patients. SRA might inhibit T cell proliferation and activation as a soluble form. These results not only revealed a previously unknown feature of soluble SRA in CHB patients but also provided broad understanding of SRA in T cell activation.

The Molecular and Structural Basis of HBV-resistance to Nucleos(t)ide Analogs

Infection with hepatitis B virus (HBV) is a worldwide health problem. Chronic hepatitis B can lead to fibrosis, liver cirrhosis, and hepatocellular carcinoma (HCC). Management of the latter two conditions often requires liver transplantation. Treatment with conventional interferon or pegylated interferon alpha can clear the virus, but the rates are very low. The likelihood, however, of viral resistance to interferon is minimal. The main problems with this therapy are the frequency and severity of side effects. In contrast, nucleos(t)ide analogs (NAs) have significantly lower side effects, but require long term treatment as sustained virological response rates are extremely low. However, long term treatment with NAs increases the risk for the development of anti-viral drug resistance. Only by understanding the molecular basis of resistance and using agents with multiple sites of action can drugs be designed to optimally prevent the occurrence of HBV antiviral resistance.

Current developments in nucleoside/nucleotide analogues for hepatitis B

There had been remarkable development in nucleos(t)ide analogues (NAs) and evolution in treatment strategies in last 15 years. Currently, there are five NAs available for chronic hepatitis B treatment, namely lamivudine, telbivudine and entecavir (nucleoside analogues), adefovir dipivoxil and tenofovir disoproxil fumarate (nucleotide analogues). The advantages of relatively infrequent side effects and easy administration per oral make NAs popular treatment options. The major drawback of earlier generation NAs is the risk of emergence of drug resistance. Current international guidelines recommend the use of more potent agents with high genetic barriers to resistance including entecavir and tenofovir as first line chronic hepatitis B treatment. However, there is no consensus regarding the subsequent treatment regimens in patients with suboptimal responses to NAs. De novo combination therapy of two NAs, response-guided therapy and roadmap concept in NAs with subsequent switch or add-on therapy can also potentially improve treatment efficacy and avoid resistance.

Application of coamplification at lower denaturation temperature-PCR sequencing for early detection of antiviral drug resistance mutations of hepatitis B virus

Nucleoside/nucleotide analogue for the treatment of chronic hepatitis B virus (HBV) infection is hampered by the emergence of drug resistance mutations. Conventional PCR sequencing cannot detect minor variants of <20%. We developed a modified co-amplification at lower denaturation temperature-PCR (COLD-PCR) method for the detection of HBV minority drug resistance mutations. The critical denaturation temperature for COLD-PCR was determined to be 78°C. Sensitivity of COLD-PCR sequencing was determined using serially diluted plasmids containing mixed proportions of HBV reverse transcriptase (rt) wild-type and mutant sequences. Conventional PCR sequencing detected mutations only if they existed in ≥25%, whereas COLD-PCR sequencing detected mutations when they existed in 5 to 10% of the viral population. The performance of COLD-PCR was compared to conventional PCR sequencing and a line probe assay (LiPA) using 215 samples obtained from 136 lamivudine- or telbivudine-treated patients with virological breakthrough. Among these 215 samples, drug resistance mutations were detected in 155 (72%), 148 (69%), and 113 samples (53%) by LiPA, COLD-PCR, and conventional PCR sequencing, respectively. Nineteen (9%) samples had mutations detectable by COLD-PCR but not LiPA, while 26 (12%) samples had mutations detectable by LiPA but not COLD-PCR, indicating both methods were comparable (P = 0.371). COLD-PCR was more sensitive than conventional PCR sequencing. Thirty-five (16%) samples had mutations detectable by COLD-PCR but not conventional PCR sequencing, while none had mutations detected by conventional PCR sequencing but not COLD-PCR (P < 0.0001). COLD-PCR sequencing is a simple method which is comparable to LiPA and superior to conventional PCR sequencing in detecting minor lamivudine/telbivudine resistance mutations.

Molecular diagnosis and treatment of drug-resistant hepatitis B virus

Oral antiviral agents have been developed in the last two decades for the treatment of chronic hepatitis B (CHB). However, antiviral resistance remains an important challenge for long-term CHB therapy. All of the clinically available oral antiviral agents are nucleoside or nucleotide analogues that target the activity of viral reverse transcriptase (RT), and all are reported to have resistant mutations. Since the hepatitis B virus (HBV) RT, like other viral polymerases, lacks proofreading activity, the emergence of drug-resistance occurs readily under selective pressure from the administration of antiviral agents. The molecular diagnosis of drug-resistant HBV is based on sequence variations, and current diagnostic methods include sequencing, restriction fragment polymorphism analysis, and hybridization. Here, we will discuss the currently available molecular diagnosis tools, in vitro phenotypic assays for validation of drug-resistant HBV, and treatment options for drug-resistant HBV.

Nucleoside/nucleotide analog inhibitors of hepatitis B virus polymerase: mechanism of action and resistance

Hepatitis B virus (HBV) polymerase and human immunodeficiency virus (HIV) reverse transcriptase are structurally related. However, the HBV enzyme has a protein priming activity absent in the HIV enzyme. Approved nucleoside/nucleotide inhibitors of the HBV polymerase include lamivudine, adefovir, telbivudine, entecavir and tenofovir. Although most of them target DNA elongation, guanosine and adenosine analogs (e.g. entecavir and tenofovir, respectively) also impair protein priming. Major mutational patterns conferring nucleoside/nucleotide analog resistance include the combinations rtL180M/rtM204(I/V) (for lamivudine, entecavir, telbivudine and clevudine) and rtA181V/rtN236T (for adefovir and tenofovir). However, development of drug resistance is very slow for entecavir and tenofovir. Novel nucleoside/nucleotide analogs in advanced clinical trials include phosphonates similar to adefovir or tenofovir, and new tenofovir derivatives with improved pharmacological properties.

Changes of HBsAg and HBV DNA levels in Chinese chronic hepatitis B patients after 5 years of entecavir treatment

BACKGROUND AND AIM

Hepatitis B surface antigen (HBsAg) kinetics during long-term entecavir therapy has not been well investigated.

METHODS

We described the cumulative serologic, virologic, and biochemical outcomes and the occurrence of signature entecavir mutations among 222 Chinese treatment-naïve chronic hepatitis B (CHB) patients receiving entecavir for up to 5 years.

RESULTS

The median rate of HBsAg reduction over 5 years was 0.125 log IU/mL/year. Patients with high baseline HBV DNA levels (≥ 8 log copies/mL or ≥ 7.3 log IU/mL), when compared with those with baseline hepatitis B virus (HBV) DNA < 7.3 log IU/mL, had a significantly greater median rate of HBsAg reduction (0.178 and 0.102 log IU/mL/year, respectively, P < 0.001). The difference in HBsAg decline was most prominent in the first year (0.324 and 0.062 log IU/mL/year, respectively, P < 0.001). Greater median rates of HBsAg reduction were also found in hepatitis B e antigen (HBeAg)-positive patients when compared with HBeAg-negative patients (0.144 and 0.098 log IU/mL/year, P = 0.015), and in patients with high baseline HBsAg levels (≥ 3 log IU/mL), when compared with patients with low baseline HBsAg < 3 log IU/mL (0.131 and 0.045 log IU/mL/year, respectively, P = 0.001). The 5-year cumulative rate of HBV DNA undetectability (< 20 IU/mL) was 97.1%. There were two cases of entecavir resistance, resulting in a 5-year cumulative resistance rate of 1.2%.

CONCLUSION

In contrast to the profound HBV DNA suppression, long-term entecavir treatment achieved only a slow decline in serum HBsAg. Although certain patient subgroups exhibit a more rapid HBsAg reduction, additional therapeutic agents are needed to increase the chance of HBsAg seroclearance in CHB.

Real-world application of the roadmap model in chronic hepatitis B patients with telbivudine therapy

BACKGROUND

The roadmap concept provides a strategy to maximize hepatitis B virus suppression and minimize drug resistance by add-on or switching therapy in patients with a suboptimal response at Week 24. The efficacy of this strategy in routine clinical practice remains to be validated.

OBJECTIVE

The aim of our study was to validate the roadmap concept in the treatment of chronic hepatitis B, and to investigate the virologic efficacy and kinetics of quantitative hepatitis B surface antigen (qHBsAg) during telbivudine therapy in a real-world setting.

METHODS

A prospective, cohort study enrolled 96 consecutive, treatment-naïve patients with chronic hepatitis B receiving telbivudine therapy. At Week 24, only 17 of 42 (40%) partial or inadequate responders (hepatitis B virus DNA 60-2000 and >2000 IU/mL, respectively) followed the roadmap model and consented to adefovir add-on therapy. The remaining patients continued to receive telbivudine monotherapy.

RESULTS

At Week 96, none of the patients receiving adefovir add-on therapy, and 28% of patients receiving telbivudine monotherapy, either partial or inadequate responders, developed genotypic resistance (P = 0.03). Poor early qHBsAg kinetics (an increase in qHBsAg >0.4 log IU/mL at Week 12) was the only significant predictor of genotypic resistance (adjusted hazard ratio = 13.83; 95% CI, 1.79-106.76; P = 0.01). Telbivudine monotherapy was efficacious in 94% of partial responders who did not have poor early qHBsAg kinetics, remaining free of drug resistance after 2 years.

CONCLUSIONS

The application of the roadmap model with add-on adefovir therapy prevented genotypic resistance. However, telbivudine monotherapy achieved a good response in the majority of partial responders who did not have poor early qHBsAg kinetics. Poor early qHBsAg kinetics was an early predictor of genotypic resistance at Week 96. Modification of the roadmap model to incorporate early qHBsAg kinetics may further optimize the efficacy of the treatment strategy of hepatitis B virus.

The Discovery and Development of a Potent Antiviral Drug, Entecavir, for the Treatment of Chronic Hepatitis B

Since the first approval of interferon for the treatment of chronic hepatitis B virus (HBV) infection in 1992, six additional antivirals have been developed: pegylated interferon-alfa2a, and the oral antivirals lamivudine, adefovir, telbivudine, entecavir and tenofovir. The availability of animal models for HBV infection and hepatocyte cell culture led to the discovery and development of oral antivirals targeted at HBV polymerase and reverse transcriptase, which inhibit viral replication. The discovery and development of entecavir, the first oral anti-HBV drug with both potent antiviral activity and a high genetic barrier to resistance, took more than 10 years before it was first approved in the USA. Since then, multiple real-life studies have provided data consistent with the findings of the registration trials and the long-term rollover study in terms of efficacy, resistance, and safety. Data from the long-term follow-up of patients enrolled in the registration studies showed that treatment with entecavir can lead to significant improvements in liver histopathology, and recent cohort studies have demonstrated that treatment with entecavir may reduce disease progression and the development of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B. In addition, real-life studies suggest that entecavir may reduce HCC recurrence and increase survival rates in patients with HBV-related HCC post-surgical resection.

Telbivudine treatment in chronic hepatitis B: experience from China

Telbivudine, one of the oral anti-hepatitis B virus (HBV) nucleoside analogues, has been used for more than 5 years to treat HBeAg-positive and -negative chronic hepatitis B (CHB) patients. This includes not only global Phase II and III trials, but also Chinese Phase III trials and several real-world clinical practice studies from China. The present review will first focus on 1-, 2- and 3-year data of telbivudine therapy on HBV DNA suppression, alanine aminotransferase (ALT) normalization, hepatitis B e antigen (HBeAg) seroconversion, viral resistance and safety in HBeAg-positive and -negative CHB patients. Second, telbivudine treatment predictors, including HBV DNA undetectability, ALT level and other immune-related markers at 12 and 24 weeks will be summarized to optimize therapy. Besides several retrospective studies, the Chinese EFFORT prospective study adapted from telbivudine virological response at 24 weeks has shown very promising results. Finally, the Chinese experience of using telbivudine in the second and third trimesters of pregnancy to prevent perinatal transmission of HBV infection will be touched on citing the latest studies.

Efficacy of telbivudine in Taiwanese chronic hepatitis B patients compared with GLOBE extension study and predicting treatment outcome by HBV DNA kinetics at week 24

Background

The aims of this study were to compare results from a Taiwanese sub-study of the GLOBE 2303 telbivudine study and evaluate the HBV DNA kinetics.

Methods

Forty-one Taiwanese patients were treated for an additional 2 years with telbivudine. Efficacy endpoints were the same as the GLOBE study. The correlations of reductions in HBV DNA levels at Week 24 were evaluated.

Results

All 7 HBeAg-positive patients with undetectable HBV DNA levels at Week 24 sustained this response at Year 4 with rates of ALT normalization 71%, HBeAg seroconversion 57%, and cumulative resistance 0%. Out of 16 HBeAg-negative patients with undetectable HBV DNA levels at Week 24, 11 (78%) sustained this response at Year 4 with rates of ALT normalization 83% and cumulative resistance 8.7%. There were significant correlations between reductions of DNA of ≥5 log₁₀ copies/mL at Week 24 with maintained PCR negativity at Years 2–4 and a lack of resistance at Year 2.

Conclusions

Long-term telbivudine efficacy in Taiwanese patients was comparable to the GLOBE 2303 study. A reduction in HBV DNA levels by ≥5 log₁₀ copies/mL at Week 24 represented the optimal cut-off point, which may predict favourable outcomes in patients with high baseline HBV DNA levels.

Trial registration

ClinicalTrials.gov Identifier: NCT00142298 (http://clinicaltrials.gov/).

Direct acting antivirals for the treatment of chronic viral hepatitis

The development and evaluation of antiviral agents through carefully designed clinical trials over the last 25 years have heralded a new dawn in the treatment of patients chronically infected with the hepatitis B and C viruses, but not so for the D virus (HBV, HCV, and HDV). The introduction of direct acting antivirals (DDAs) for the treatment of HBV carriers has permitted the long-term use of these compounds for the continuous suppression of viral replication, whilst in the case of HCV in combination with the standard of care [SOC, pegylated interferon (PegIFN), and ribavirin] sustained virological responses (SVRs) have been achieved with increasing frequency. Progress in the case of HDV has been slow and lacking in significant breakthroughs.This paper aims to summarise the current state of play in treatment approaches for chonic viral hepatitis patients and future perspectives.

Outcome of Lamivudine-Resistant Chronic Hepatitis B after up to 5 Years of Combination Therapy with Adefovir

Background

There is a paucity of data on the long-term efficacy of combination lamivudine and adefovir therapy in patients with lamivudine-resistant chronic hepatitis B.

Methods

We determined the cumulative virological, serological and biochemical outcomes of 165 lamivudine-resistant chronic hepatitis B patients on lamivudine and adefovir for up to 5 years. Resistance profiles using a line probe assay were determined among patients with detectable viraemia. The significance of different baseline and on-treatment virological parameters was analysed.

Results

The median age and duration of follow-up were 45.1 years and 37.1 months, respectively. The cumulative rates of HBV DNA undetectability (<20 IU/ml), alanine aminotransferase normalization and hepatitis B e antigen seroconversion up to 5 years were 74.0%, 95.1% and 44.4%, respectively. One patient achieved hepatitis B surface antigen seroclearance. The 5-year cumulative resistance rate to adefovir was 10.2%. Among different baseline and on-treatment virological parameters, week 24 HBV DNA<200 IU/ml was associated with an increased chance of long-term virological suppression ( P<0.001, OR 13.89, 95% CI 3.90, 49.46). Primary non-response and high baseline viral titres were not useful in predicting long-term virological outcomes. The 5-year cumulative rate of serum creatinine elevation >0.5 mg/dl was 4.1%.

Conclusions

Combination lamivudine and adefovir therapy for up to 5 years achieved modest rates of virological suppression, but resistance developed in only 10.2% of patients. Week 24 HBV DNA<200 IU/ml was predictive of favourable long-term virological outcomes and could be used to assist treatment decisions on continuing lamivudine and adefovir or switching to more potent therapy.

Current Antiviral Therapy of Chronic Hepatitis B: Efficacy and Safety

The treatment of chronic hepatitis B is in constant evolution. Interferon, the first agent licensed for chronic hepatitis B treatment, has been superseded by the growing popularity of nucleoside/nucleotide analogues (NA). However, resistance to these agents is a major challenge. Newer NAs, such as entecavir and tenofovir dipivoxil fumarate, have very low resistance rates and favorable safety profiles. Long-term use of these agents can effectively suppress hepatitis B virus DNA, leading to decrease in incidence of hepatitic flares, as well as in the development of cirrhosis and hepatocellular carcinoma. The efficacy and safety of various antiviral agents is discussed in this review.

Effect and Predictive Elements for 52 Weeks' Telbivudine Treatment on Naïve HBeAg positive Chronic Hepatitis B

BACKGROUND

Antiviral treatment with nucleoside analogs has been used for chronic hepatitis B (CHB). Each kind of nucleoside analog has its own characteristics and suitability for patients. Telbivudine (LdT, brand name: Sebivo, Beijing Novartis Pharma Ltd) is the newest nucleoside analog, with strong and rapid viral suppression. However, its resistance rate is relatively high during long-term application, due to low genetic barriers to resistance. So, it is necessary to increase the effect and reduce resistance with effective management, according to baseline factors and early on-treatment responses.

OBJECTIVES

To reveal possible predictive factors of the effect of telbivudine (LdT) treatment on naïve HBeAg-positive chronic hepatitis B (CHB) patients to optimize treatment.

PATIENTS AND METHODS

A total 71 naïve chronic hepatitis B (CHB) patients who met the inclusion criteria were enrolled. All patients were treated with LdT 600 mg Qd for at least 52 weeks. Multiple logistic regression analyses were done to investigate the predictive values of baseline factors and responses at Week 24.

RESULTS

The reduction in hepatitis virus B (HBV) DNA level was 6.44 ± 2.38 lg copies/mL at Week 52 compared with baseline. The complete virus response (CVR), biochemical response (BR), serological response (SR), and drug resistance (DR) were 61.99%, 77.46%, 35.21%, and 8.45% respectively. By multiple regression analysis, baseline alanine aminotransferase (ALT) levels significantly affected CVR (P = 0.024, OR = 1.008), and baseline ALT and baseline HBV DNA levels were independent compact factors of SR (P = 0.012, OR = 1.007; P = 0.001, OR = 0.423). The differences in CVR, SR, and DR in patients with ALT > 120 Iu/mL compared with patients with ALT ≤ 120 Iu/mL were statistically significant. The differences in SR in patients with HBV DNA > 107 copies/mL compared with patients with HBV DNA ≤ 107 copies/mL were statistically significant. Additionally, CVR, BR, and SR were differed significantly between patients with HBV DNA lower than 300 copies/mL at Week 24 and patients with HBV DNA higher than 300 copies/mL (P = 0.000, P = 0.0016, and P = 0.000, respectively).

CONCLUSIONS

There were more responders among naïve HBeAg-positive chronic hepatitis B patients with lower HBV DNA levels (especially lower than 107 copies/mL) and higher ALT values (especially higher than 120 Iu/mL at baseline) to LdT treatment. Adjustments for treatment strategy should be considered if HBV DNA > 300 copies/mL at Week 24 is observed.

Nucleoside/nucleotide analogues in the treatment of chronic hepatitis B

The current available agents for the treatment of chronic hepatitis B (CHB) include immunomodulatory agents, such as interferon-α and pegylated interferon-α, and oral nucleoside/nucleotide analogues (NAs), including lamivudine, adefovir, telbivudine, entecavir and tenofovir. The NAs work mainly by inhibiting hepatitis B virus (HBV) DNA polymerase activity and thus suppress HBV replication. Oral NAs have become the mainstay of CHB treatment, mainly due to their profound viral suppressive effects and also due in part to the ease of single daily dosing and lack of significant side effects. One major drawback of NA therapy is the development of drug resistance mutations with long-term treatment. Lamivudine, the first oral NA approved for CHB patients, is associated with high rates of drug resistance, with resultant virological relapse and biochemical flare. Fortunately, newer and more potent NAs, such as entecavir and tenofovir, have very low resistance rates, with potent and durable viral suppression. This review is aimed at the current developments in NAs for CHB treatment, detailing the mechanisms of antiviral activity of the different agents, the efficacy of viral suppression, the achievement of treatment endpoints, the development of drug resistance and the optimal strategies for using these drugs.

Tenofovir disoproxil fumarate for the treatment of chronic hepatitis B monoinfection

INTRODUCTION

Resistance in nucleoside/nucleotide analog (NA) therapy has always been a challenge in the management of chronic hepatitis B (CHB).

CLINICAL STUDIES

Initially developed for the treatment of HIV infection, early in vitro and clinical observational studies had shown tenofovir disoproxil fumarate (TDF) to be also active against CHB. Recent data from various multicenter phase 3 and 4 clinical trials have confirmed TDF being able to achieve a high viral suppression in both NA-naive and -experienced CHB patients. There are also emerging data on the efficacy of TDF in decompensated CHB. Although there are in vitro studies identifying certain mutation loci associated with a reduced susceptibility to TDF, there have so far been no reports of virologic resistance to TDF in clinical studies. TDF has a favorable safety profile, although more long-term data would be needed.

CONCLUSIONS

TDF has the makings of an "ideal" first-line drug for the treatment of CHB.