Virologic monitoring of hepatitis B virus therapy in clinical trials and practice: recommendations for a standardized approach

Medication nonadherence with long-term management of patients with hepatitis B e antigen-negative chronic hepatitis B

BACKGROUND AND AIMS

Antiviral treatment responses for patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) are well-defined by data from registration trials but may differ from patients seen in community settings where medical adherence is usually not as strictly monitored. The goal of this study was to examine the long-term outcomes of HBeAg-negative patients in a community clinical setting.

METHODS

We performed a cohort study of 189 consecutive treatment-naïve patients with CHB who were treated with either entecavir (ETV) 0.5 mg daily (n=107) or adefovir dipivoxil (ADV) 10 mg daily (n=82) from 2002 to 2009 at two community clinics.

RESULTS

All patients were Asians. Both ETV and ADV cohorts had similar median baseline ALT and HBV DNA levels. By year 4, a similar proportion of ETV and ADV patients who remained on monotherapy achieved complete viral suppression (91-96%); however, more patients in the ADV cohort required alternative therapy (27 vs. 5%). No patients in the ETV cohort developed resistance while 18% of the ADV cohort did. Cumulative nonadherence rates were 10 and 12% in ADV and ETV cohorts, respectively.

CONCLUSIONS

Failure to monotherapy in a community clinical setting is due to both antiviral resistance and patient nonadherence. Medication nonadherence is likely to be a more important contributor to treatment failure than antiviral resistance, especially with new anti-HBV agents such as ETV and tenofovir.

Performance characteristics and comparison of Abbott and artus real-time systems for hepatitis B virus DNA quantification

Virological monitoring of hepatitis B virus (HBV) DNA is critical to the management of HBV infection. With several HBV DNA quantification assays available, it is important to use the most efficient testing system for virological monitoring. In this study, we evaluated the performance characteristics and comparability of three HBV DNA quantification systems: Abbott HBV real-time PCR (Abbott PCR), artus HBV real-time PCR with QIAamp DNA blood kit purification (artus-DB), and artus HBV real-time PCR with the QIAamp DSP virus kit purification (artus-DSP). The lower limits of detection of these systems were established against the WHO international standards for HBV DNA and were found to be 1.43, 82, and 9 IU/ml, respectively. The intra-assay and interassay coefficients of variation of plasma samples (1 to 6 log(10) IU/ml) ranged between 0.05 to 8.34% and 0.16 to 3.48% for the Abbott PCR, 1.53 to 26.85% and 0.50 to 12.89% for artus-DB, and 0.29 to 7.42% and 0.94 to 3.01% for artus-DSP, respectively. Ninety HBV clinical samples were used for comparison of assays, and paired quantitative results showed strong correlation by linear regression analysis (artus-DB with Abbott PCR, r = 0.95; Abbott PCR with artus-DSP, r = 0.97; and artus-DSP with artus-DB, r = 0.94). Bland-Altman analysis showed a good level of agreement for Abbott PCR and artus-DSP, with a mean difference of 0.10 log(10) IU/ml and limits of agreement of -0.91 to 1.11 log(10) IU/ml. No genotype-specific bias was seen in all three systems for HBV genotypes A, C, and D, which are predominant in this region. This finding illustrates that the Abbott real-time HBV and artus-DSP systems show more comparable performance than the artus-DB system, meeting the current guidelines for assays to be used in the management of hepatitis B.

Current status of antiviral therapy for hepatitis B

Chronic hepatitis B (CHB) is a major public health problem affecting up to 400 million people globally. Complications of CHB including liver failure and hepatocellular carcinoma result in 1.2 million deaths per year, making CHB the 10th leading cause of mortality worldwide. The natural history of CHB is variable and complex. The past decade witnessed important developments for the therapy of hepatitis B and marked the new era of oral therapy. The ultimate goal of CHB therapy is to arrest the progression of liver injury and to prevent the development of liver failure and hepatocellular carcinoma. Currently, six agents are approved for the treatment of CHB. Each of these agents, given as monotherapy, has been shown to produce virological, biochemical, and histological benefits for both HBeAg positive and negative CHB. There are, however, limitations in spite of their efficacy. The significant side-effect profile of interferon, for example, limits its long-term use. The approved oral agents are tolerable with prolonged use but drug resistance could limit long-term monotherapy. To date, combination therapy with nucleoside analogue and pegylated interferon or two nucleos(t)ide analogues given for one year does not show superiority in durability of response compared to monotherapy. Ongoing research effort is critical to identify the ideal hepatitis B therapy that is safe, effective, and produces durable response with a finite course of therapy. It is equally important to conduct a well designed, prospective natural history study to identify predictors of disease progression. This will accurately guide treatment strategy for this important disease.

Three years of continuous entecavir therapy in treatment-naïve chronic hepatitis B patients: VIRAL suppression, viral resistance, and clinical safety

OBJECTIVES

We aimed to determine the antiviral potency, viral resistance rate, and clinical safety of 3-year continuous entecavir treatment.

METHODS

We determined the cumulative rates of undetectable hepatitis B virus DNA (HBV DNA) levels (< 12 IU/ml), hepatitis B e antigen (HBeAg) seroconversion, alanine aminotransferase (ALT) normalization, and entecavir signature mutations (using the sensitive line probe assay) and monitored any side effects for 222 treatment-naïve chronic hepatitis B (CHB) patients (40.5% HBeAg positive) on continuous entecavir treatment for 3 years.

RESULTS

The median age and follow-up duration were 45 years and 25.1 months, respectively. In all, 222, 188, and 101 patients had been followed up for at least 1, 2, and 3 years, respectively. There were incremental increases in the rates of HBV DNA undetectability, HBeAg seroconversion, and ALT normalization reaching to 92.1, 43.9, and 90.4% at year 3, respectively. In all, 100 and 76.5% of patients with baseline HBV DNA levels < and ≥ 8 logs copies/ml, respectively, had undetectable HBV DNA at year 3. The cumulative rate of entecavir-resistant mutations was 1.2% at year 3. Three patients experienced virologic breakthrough, one with resistance development, one with subsequent HBeAg seroconversion, and one with subsequent decline in HBV DNA. Two patients with baseline rt204I mutations responded to entecavir treatment. There were no serious adverse events.

CONCLUSIONS

Using very sensitive HBV DNA and viral resistance assays, continuous entecavir treatment for treatment-naïve CHB patients for 3 years was associated with >90% chance of undetectable HBV DNA and only 1.2% chance of emergence of entecavir-resistant mutations.

Quantitation of HBV covalently closed circular DNA in micro formalin fixed paraffin-embedded liver tissue using rolling circle amplification in combination with real-time PCR

BACKGROUND

The study aimed to develop an effective method to quantitate HBV covalently closed circular DNA (cccDNA) using small section of formalin fixed paraffin-embedded (FFPE) liver biopsy.

METHODS

Plasmid-safe ATP-dependent DNase (PSAD)-treated samples were subjected to rolling circle amplification (RCA) prior to real-time PCR mediated by cccDNA-selective primers. Human beta-actin gene was used as a reference control.

RESULTS

Compared to the classical method, i.e., PSAD digestion+real-time PCR, introduction of RCA increased the lower limit of detection for about 2 logs with good inter- and intra-assay reproducibility. HBV cccDNA was detected in 91.5% (119/130) of the FFPE samples. The cccDNA levels (copy/cell) between FFPE liver tissues and fresh frozen counterpart tissues were comparable. The median of cccDNA level in HBeAg-positive patients was higher than that in HBeAg-negative ones (52.60 vs. 31.25copies/cell, P<0.01). Intrahepatic cccDNA level was positively correlated with intrahepatic HBV total DNA level, but not obviously correlated with serum HBV DNA or alanine aminotransferase levels.

CONCLUSIONS

The method could sensitively and specifically quantitate intrahepatic HBV cccDNA in micro FFPE liver biopsy tissue for evaluation of HBV replication status in the liver.

Evaluation of peptide nucleic acid array for the detection of hepatitis B virus mutations associated with antiviral resistance

A major problem of long-term antiviral therapy in chronic hepatitis B patients is the emergence of hepatitis B virus (HBV) mutations associated with drug resistance. Recently, a new array using peptide nucleic acids (PNAs), which are synthetic nucleic acid analogues, was developed for the detection of HBV mutations at six different codon positions associated with lamivudine (LAM) and adefovir (ADV) resistance. We compared the PNA array with direct sequencing and reverse hybridization (INNO-LiPA) in 73 samples obtained from chronic hepatitis B patients. The PNA array detected mutations associated with LAM and/or ADV resistance in 60 (82.2%) of the 73 samples. The overall concordance rate of PNA array and INNO-LiPA compared with direct sequencing was 99.5% and 98.2%, respectively. The rate of complete concordance between PNA array and INNO-LiPA was 92.7%. The PNA array assay results were comparable with INNO-LiPA for detection of HBV mutations associated with antiviral resistance.

Detection of lamivudine- or adefovir-resistant hepatitis B virus mutations by a liquid array

A novel polymerase chain reaction (PCR)-Luminex assay was developed for rapid, accurate, and high-throughput detection of the most important hepatitis B virus (HBV) variants, including those with reverse transcriptase (RT) domain L180M, M204I/V, A181T/V/S, I233V and N236T mutations associated with resistance to lamivudine (LAM) or adefovir (ADV). Using mixtures of mutant and wild-type HBV, this method was sufficiently sensitive for detecting 10(3)HBV ml(-1) and could detect minor mutants when they comprised 5% of the total viral population. Comparison of the PCR-Luminex assay with INNO-LiPA for detecting clinical LAM- or ADV-resistant chronic hepatitis B virus infection in 64 patients confirmed the following: the 2 methods were 97.9% (48 of 49) and 93.3% (14 of 15) concordant for detecting LAM- or ADV-resistance mutations, respectively. The agreement with direct sequencing was 70.3% (45 of 64). The PCR-Luminex assay or multi-analyte suspension array can detect simultaneously and efficiently minor populations HBV mutants early during infection in many clinical samples. It is a simple, cost-effective method for resistance surveillance or selecting appropriate antiviral agents and initiating timely rescue treatment before the development drug-resistance related virus or biochemical breakthrough.

Treatment of chronic hepatitis B: update of the recommendations from the 2007 Italian Workshop

The Italian recommendations for the therapy of hepatitis B virus (HBV)-related disease were issued in 2008. Subsequently in 2008 the nucleotide analogue (NA) Tenofovir was approved for antiviral treatment. The introduction of this important new drug has called for the current guidelines update, which includes some additional revisions: (a) the indication for therapy is extended to mild liver fibrosis and the indication for treatment is graded as "possible", "optional" or "mandatory" according to the fibrosis stage; (b) two different treatment strategies are described: first line definite duration treatment with interferon, long-term treatment of indefinite duration with NA; (c) the indication to follow either strategy is also based on the stage of liver fibrosis; (d) virological monitoring is modified to include the definitions of failure and of sustained virological response to interferon therapy; (e) the recommendation to use HBV DNA assays with high sensitivity and wide linear ranges is underlined (f) guidelines on post-treatment follow-up after finite treatment with NA, potential side effects of therapy and non-virological monitoring are defined; (g) definitions and treatment of patients without optimal response to NA are reported; (f) treatment and monitoring of compensated or decompensated cirrhosis and hepatocellular carcinoma are updated.

Genotypic resistance profile of hepatitis B virus (HBV) in a large cohort of nucleos(t)ide analogue-experienced Chinese patients with chronic HBV infection

The study investigated the hepatitis B virus (HBV) genotypic resistance profile in 1803 nucleos(t)ide analogue (NA)-experienced Chinese patients with chronic HBV infection. Serum HBV DNA was extracted, and the reverse transcriptase region was analysed by a high-sensitive direct PCR sequencing and verified by clonal sequencing if necessary. Drug-resistant mutations were detected in 560 of the 1803 patients, including 214 of 490 patients who received lamivudine (LAM), 35 of 428 patients who received adefovir (ADV), five of 18 patients who received telbivudine and 306 of 794 patients who received various sequential/combined NA therapies. ADV-resistant mutations were detected in 36 of 381 patients who received LAM and then switched-to ADV in contrast to one of 82 patients who received ADV add-on LAM. Entecavir (ETV)-resistant mutations were detected not only in LAM- and ETV-treated patients but also in LAM-treated ETV-naïve patients. Double mutations rtM204I and rtL180M were detected more frequently in genotype C than in genotype B virus, and patients infected with this mutant had higher alanine transaminase levels than those infected with mutant containing the rtM204I substitution alone. Multidrug-resistant HBV strains were identified in eight patients, including two novel strains with mutational patterns rtL180M + A181V + S202G + M204V + N236T and rtL180M + S202G + M204V + N236T. The results provide new information on HBV genotypic resistance profiles in a large cohort of Chinese patients with chronic HBV infection and may have important clinical implication for HBV drug resistance management in China.

An overview of treatment response rates to various anti-viral drugs in Pakistani hepatitis B virus infected patients

Hepatitis B virus (HBV) is one of the leading health problem with up to 350 million affected people worldwide including 4.5 million only in Pakistan. It has mortality rate of 0.5 to 1.2 million per year worldwide. Pakistan lies in the endemic region with 3-5% HBV carrier rate in the country. The present article reviews the literature on the treatment response of HBV prevalent in Pakistani population. The average treatment response of Lamivudine and interferon-α is 25.81% and 47.95%, respectively. Peg-Interferon was shown to be not effective against the HBV/HCV (hepatitis C virus)/HDV (hepatitis Delta virus) co-infection. The present study reveals that interferon-α is the most effective therapy available for HBV infection prevalent in Pakistani population. Genotype C & D are the most common HBV genotypes in Pakistan and are associated with increased severity and less response to interferon therapy. This poses a great challenge for physicians and researchers and further studies are needed to describe the outcome of the current therapies recommended against HBV infection in Pakistani population.

Variable influence of mutational patterns in reverse-transcriptase domain on replication capacity of hepatitis B virus isolates from antiviral-experienced patients

BACKGROUND

Various mutations in reverse-transcriptase domain (RT) of hepatitis B virus (HBV) polymerase may develop during antiviral therapy. The influence of these mutational patterns on HBV replication capacity remains to be fully clarified.

METHODS

Nine clones containing complete HBV genomes were isolated from 5 patients with chronic hepatitis B who had received antiviral treatment. Viral replication capacity was measured by quantitation of HBV replicative intermediates using vector-free transfer of paired mutant and wild-type HBV genomes into human hepatoma cell lines HepG2 and Huh7. HBV pgRNA was quantitated by real-time PCR and Southern blot analysis.

RESULTS

A real-time PCR assay with high sensitivity and small variation was developed for quantitation of HBV replicative intermediates. Compared to wild-type counterpart, mutant rtL217P produced 1.98-fold higher replicative intermediate level, and mutant rtM204I+rtL217P increased the replicative intermediate level to 1.20 fold. Other mutational patterns (rtV173M, rtA181S/V, rtM204I, rtQ215H, rtL229M, rtN238H, rtV84M+rtA181S+rtM204I, rtV84M+rtM204I, rtA181S+rtM204I, rtA181V+rtL229M, rtQ215H+rtN238H) reduced viral replication capacity to different extents.

CONCLUSIONS

The study offers a practical measurement assay and novel information for replication features of mutant strains; especially, rtL217P substitution likely represents an energetic replication-compensatory mutation.

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.

A real-time quantitative assay for hepatitis B DNA virus (HBV) developed to detect all HBV genotypes

Hepatitis B virus (HBV) is a major cause of chronic liver disease worldwide. Besides genotype, quantitative analysis of HBV infection is extensively used for monitoring disease progression and treatment. Affordable viral load monitoring is desirable in resource-limited settings and it has been already shown to be useful in developing countries for other viruses such as Hepatitis C virus (HCV) and HIV. In this paper, we describe the validation of a real-time PCR assay for HBV DNA quantification with TaqMan chemistry and MGB probes. Primers and probes were designed using an alignment of sequences from all HBV genotypes in order to equally amplify all of them. The assay is internally controlled and was standardized with an international HBV panel. Its efficacy was evaluated comparing the results with two other methods: Versant HBV DNA Assay 3.0 (bDNA, Siemens, NY, USA) and another real-time PCR from a reference laboratory. Intra-assay and inter-assay reproducibilities were determined and the mean of CV values obtained were 0.12 and 0.09, respectively. The assay was validated with a broad dynamic range and is efficient for amplifying all HBV genotypes, providing a good option to quantify HBV DNA as a routine procedure, with a cheap and reliable protocol.

Performance of version 2.0 of the Cobas AmpliPrep/Cobas TaqMan real-time PCR assay for hepatitis B virus DNA quantification

The detection and quantification of hepatitis B virus (HBV) DNA are essential for the diagnosis and treatment of chronic HBV infection. The use of real-time PCR assays for HBV DNA quantification is strongly recommended. The goal of this study was to evaluate the intrinsic characteristics and clinical performance of version 2.0 (v2.0) of the Cobas AmpliPrep/Cobas TaqMan (CAP/CTM) assay, a fully automated platform for HBV DNA quantification in serum or in plasma with a claimed lower limit of detection of 20 IU/ml and a claimed upper limit of quantification of 1.7 × 10(8) IU/ml. The specificity of the assay was 99% (95% confidence interval, 94.7 to 100%). Intra-assay and interassay coefficients of variation ranged from 0.21% to 2.67% and from 0.65% to 2.25%, respectively. The calibration of the assay was found to be satisfactory. Study of blood specimens from patients infected with HBV genotypes A to F showed good correspondence between HBV DNA levels measured by the CAP/CTM v2.0 assay, version 1.0 of the same assay, and the third-generation "branched DNA" assay. The CAP/CTM v2.0 assay quantified HBV DNA levels in serum or plasma from the same patients equally. In conclusion, the new version of the CAP/CTM assay is sensitive, specific, and reproducible. It accurately quantifies HBV DNA levels in patients chronically infected with HBV genotypes A to F. Improvements made to ensure equal quantification of HBV DNA in serum and plasma have been successful. Overall, the CAP/CTM assay, version 2.0, is well suited to monitoring clinical HBV DNA levels according to current clinical practice guidelines.

Drug resistance in antiviral therapy

The introduction of nucleos(t)ide analog therapy has seen the emergence of antiviral drug resistance, which has become the main factor limiting the long-term application of these antiviral agents for patients with chronic hepatitis B. The prevention of resistance requires the adoption of strategies that effectively control virus replication and exploit an understanding of the mechanisms and processes that drive the emergence of drug resistance, namely high replication rates, low fidelity of the hepatitis B virus rt/polymerase, selective pressure of the nucleos(t)ide analog, role of replication space (liver turnover), fitness of the mutant, and genetic barrier to the drug.

Main mutations in the hepatitis B virus basic core promoter (A1762T/G1764A) before HBeAg loss are markers that identify patients who will require long-term treatment

BACKGROUND

Some patients continue to have detectable HBV-DNA levels with liver disease progression after hepatitis B e antigen (HBeAg) loss. It is important to identify these patients, candidates for long-term treatment.

AIMS

To evaluate hepatitis B virus (HBV) genotype and the main mutations in the basic core promoter (BCP, A1762T/G1764A) and precore (G1896A) sequences as markers of persistent HBV-DNA after HBeAg loss.

METHODS

We analysed 60 serum samples from 20 Caucasian, HBeAg-positive, chronic hepatitis B patients, who lost HBeAg and were followed-up longitudinally. HBV genotype and precore and BCP mutations were determined before, at the time of, and after HBeAg loss.

RESULTS

After HBeAg loss, eight (40%) patients continued to have undetectable HBV-DNA and 12 (60%) had persistent HBV-DNA (median level 4.7 log(10) copies/mL). The presence of BCP mutations prior to therapy was the only variable associated with persistently detectable viraemia (P = 0.017). Four patients with genotype A and no mutations in the BCP region experienced hepatitis B surface antigen (HBsAg) loss after a mean period of 35 months from baseline.

CONCLUSIONS

Main BCP mutations in HBeAg-positive patients are useful markers to identify patients who will not have sustained virological suppression after HBeAg loss and therapy discontinuation and could benefit from long-term treatment.

Acute hepatitis B infection associated with drug-resistant hepatitis B virus

BACKGROUND

Pre-existing antiviral-resistant hepatitis B virus (HBV) has been associated with primary non-response to lamivudine treatment in patients with chronic hepatitis B, but little is known of the capacity for resistant HBV to cause primary infection.

OBJECTIVE

The study was to investigate if Beijing patients with acute hepatitis B (AHB) are infected with drug-resistant HBV.

STUDY DESIGN

Sera were collected from 201 NA-untreated patients with AHB. Direct polymerase chain reaction (PCR) sequencing was used to screen HBV reverse-transcriptase (RT) domain and clonal sequencing were performed for all resistance-positive samples.

RESULTS

Direct PCR sequencing showed that 14 samples (7.0%) were positive for drug-resistant HBV variants, comprised of 11 with the lamivudine-resistant pattern rtM204I and/or rtM204V in the presence and absence of compensatory mutations rtL80I, rtV173L, and rtL180M; two with the adefovir-resistant pattern rtA181V; and one with the entecavir-resistant pattern rtL180M+rtS202G+rtM204V. Concomitance of resistance variants with wild-type HBV was observed in samples from 13 patients. Clonal sequencing verified direct sequencing results. Furthermore, variants associated with resistance to adefovir or entecavir were found in 3 samples.

CONCLUSIONS

Drug-resistant HBV strains, including those not resistant to lamivudine, are transmissible and can cause acute hepatitis B in China.

Simvastatin potentiates the anti-hepatitis B virus activity of FDA-approved nucleoside analogue inhibitors in vitro

Statins are 3-hydroxyl-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors used for the treatment of hypercholesterolemia. We report that a particular statin, simvastatin (SIM), exhibits strong in vitro anti-HBV activity. Moreover, a combination of SIM with each of the individual nucleos(t)ide analogues lamivudine (LMV), adefovir (ADV), tenofovir (TEN) and entecavir (ETV), showed synergistic antiviral activity. Combination drug treatments were performed in the HepG2.2.15 cell line. Compound combinations were centered on a mixture designed to deliver approximately equipotent (not necessarily equimolar) concentrations of each agent, based on the ninety percent viral inhibition monotherapy values. SIM interacted favorably with all four licensed anti-HBV nucleos(t)ide analogues, especially at molar ratios that approximate combinations likely to be used clinically. As the relative concentration of SIM was raised to an excess, the overall favorability of the interactions progressively increased. SIM displayed about equal degrees of synergy with ADV and TDF. The highest degree of synergy was observed at the 300:1 combination of SIM with ETV. Interactions with LMV were the least favorable. The in vitro potential shown here may greatly augment anti-HBV therapy clinically.

Antiviral treatment of chronic hepatitis B virus (HBV) infections

While 25 compounds have been formally licensed for the treatment of HIV infection (AIDS), only seven licensed products are currently available for the treatment of chronic hepatitis B virus (HBV) infection: interferon-α, pegylated interferon-α, lamivudine, adefovir (dipivoxil), entecavir, telbivudine and tenofovir (disoproxil fumarate). In contrast to the treatment of HIV infections where the individual drugs are routinely used in combination, for the treatment of chronic HBV infection the individual drugs are generally used in monotherapy. In principle, combination drug therapy should allow reducing the likelihood of drug-resistant development.

[4. Austrian consensus-statement for diagnosis and therapy of hepatitis B 2009]

Hepatitis B is the most common chronic viral infection of the liver. Chronic hepatitis B is estimated to affect at least 350 million people worldwide and is the leading cause of death from liver disease. There have been dramatic developments both in the diagnostic field and in drug treatment of chronic hepatitis B. Today, chronic hepatitis B is a well manageable disease in the vast majority of cases and the main challenge remains the detection of affected patients at an early enough disease stage to prevent end-stage liver disease and its complications. The rapid pace of drug development mandated an update of the Austrian guidelines on the treatment of hepatitis B, which after 1994 and 1998 were now dating back to 2005 in their third version. All chapters from the 3. consensus statement from 2005 were renewed except for the chapter on liver biopsy, which is still valid in its 2005-version. In particular, virologic parameters take now center stage for treatment decisions, HBV-genotyping is now being considered for the choice of treatment, and the oral first line treatment for chronic hepatitis B has been changed. Overall this consensus statement accounts for the major advances in the management of hepatitis B and significantly changes clinical management of patients with hepatitis B in Austria.

Comparison between quantitative hepatitis B surface antigen, hepatitis B e-antigen and hepatitis B virus DNA levels for predicting virological response to pegylated interferon-alpha-2b therapy in hepatitis B e-antigen-positive chronic hepatitis B

AIM

The aim of this study was to compare the clinical applicability of quantitative serum hepatitis B surface antigen (HBsAg), hepatitis B e-antigen (HBeAg) and hepatitis B virus (HBV) DNA for predicting virological response (VR) to pegylated interferon (PEG-IFN) therapy.

METHODS

Thirty HBeAg-positive chronic hepatitis B patients who received PEG-IFN-alpha-2b for 48 weeks were enrolled. Quantitative HBsAg, HBeAg and HBV DNA were measured before, during and after the therapy. Paired liver biopsies were performed before and after treatment for covalently closed circular (ccc)DNA and intrahepatic HBV DNA analysis.

RESULTS

VR at 48 weeks post-treatment, defined as HBeAg seroconversion and HBV DNA less than 10 000 copies/mL was achieved in 10 (33.3%) patients. Responders had significantly lower baseline HBsAg, HBeAg, cccDNA and intrahepatic HBV DNA levels than non-responders. Baseline and reduced levels of log(10) HBsAg and log(10) HBeAg correlated well with those of log(10) cccDNA and log(10) total intrahepatic HBV DNA. Responders showed consistent decrease in serum HBsAg, HBeAg and HBV DNA levels during therapy. HBeAg level of 2.0 log(10) sample to cut-off ratio at week 24 on therapy provided the best prediction of sustained virological response, with sensitivity and negative predictive values of 85% and 92%, respectively. One patient (3.3%) who cleared HBsAg at follow up exhibited a more rapid decline in serum HBsAg during therapy than those who developed VR without HBsAg clearance.

CONCLUSION

Quantitative measurement of serum HBeAg during therapy may be superior to serum HBsAg and HBV DNA as a prediction of HBeAg seroconversion. Kinetics of HBsAg levels on therapy may help predict HBsAg clearance after treatment.

rtE218G, a novel hepatitis B virus mutation with resistance to adefovir dipivoxil in patients with chronic hepatitis B

Antiviral therapy is a potentially successful approach for the treatment of patients with Hepatitis B virus (HBV) infection. One antiviral agent is the nucleoside analogue adefovir dipivoxil (ADV). Its efficiency is compromised by the emergence of drug-resistant HBV mutants. Although three major ADV-resistant mutations of HBV are known, rtA181T/V and rtN236T, HBV mutations associated with ADV resistance have not been fully identified. We analyzed DNA sequences that covered a 244 base pair region of the HBV polymerase gene from patients with clinical manifestations of ADV resistance. A novel pattern of amino acid substitutions in HBV polymerase was detected in 26 out of 86 patients. This mutant exhibited a substitution of glycine for glutamic acid at residue 218 (rtE218G). Transient transfection of the HBV replication-competent construct including the rtE218G mutation was performed in HepG2 cells in order to determine the relevance of this mutation to ADV resistance. Phenotypic analyses demonstrated that the rtE218G mutation could independently confer resistance to ADV in vitro, with a 50% inhibitory concentration (IC(50)) 5.5-fold higher than wild-type HBV. RtE218G-mutated HBV also showed a decreased replication capacity in vitro, equal to 87% of wild-type HBV. The present study showed that the rtE218G mutation may be a novel ADV-resistant mutation. Further work will focus on resistance surveillance and cross-resistance analyses, and the molecular mechanisms involved.

End points of therapy in chronic hepatitis B

This review assesses the relevance of the clinical, histological, biochemical and virological end points in the course and outcome of chronic hepatitis B. The pathway and the impact of the variation in these end points are presented, as well as their definitions. The treatment goals are discussed in terms of quality of life and survival. Prevention of the progression of the disease to cirrhosis, decompensated cirrhosis, end-stage liver disease and hepatocellular carcinoma seems to be the best approach to improve survival. As these criteria are long-term end points, easier to use end points assessed in clinical trials as efficacy objectives were also analyzed to determine whether they can be used as accurate surrogate criteria. Results of therapy were then analyzed according to the approved end points and in terms of management of chronic hepatitis B. Finally, an attempt to define new clinical end points is discussed in view of the development of more potent antiviral strategies.

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.

Naturally occurring amino-acid substitutions to nucleos(t)ide analogues in treatment naive Turkish patients with chronic hepatitis B

Naturally occurring amino-acid substitutions in the hepatitis B virus (HBV) polymerase gene may be responsible for resistance to nucleoside/nucleotide (NUCs) analogues. To date, only pre-existing lamivudine resistance has been extensively studied. The aim of the present study was to determine the naturally occurring or pre-existing amino-acid substitutions related to NUCs in treatment naive Turkish patients with chronic hepatitis B (CHB). The investigation involved a total of 88 patients (65 males and 23 females; mean age, 34 years; range, 15-61 years) who were diagnosed with CHB between April 2008 and January 2009. According to HBeAg status, 66 patients were HBeAg-negative and 22 patients were HBeAg positive. Naturally occurring substitutions in the HBV polymerase region were detected by DNA sequencing in 17 (19%) and 30 (34%) patients, based on manual and geno2pheno tool database interpretation, respectively. Each amino-acid substitution appeared alone and included rtA194T, rtV214A, rtQ215S, rtI233V and rtN236T. The median values for viral load, ALT and AST were 3.3 log(10) (2.0-6.0) IU/mL, 36 (12-515) U/L and 27 (13-284) U/L, respectively, but these did not correlate with the observed amino-acid substitutions in the polymerase region. By direct sequencing, genotype D of HBV was found to still be dominant among Turkish patients. In conclusion, every patient who is diagnosed with CHB should be monitored before the start of treatment for more effective management of patient treatment options.

Hepatitis B therapies and antiviral resistance detection and management

Hepatitis B virus (HBV) infection is an important health problem and a major cause of chronic hepatitis that can lead to cirrhosis and hepatocellular carcinoma. Durable viral suppression has been documented to lower the risk of hepatocellular carcinoma and disease progression. Treatment of chronic HBV infection remains a major clinical challenge because long-term use with approved oral antiviral agents is associated with drug resistance. Antiviral resistance can result in poor clinical outcomes; therefore first-line therapy with the most potent agent(s) is recommended to lower the risk. Early detection of resistance is paramount to possibly reduce the risk of liver-related morbidity and mortality. It is important that clinicians monitor for therapeutic efficacy and resistance, so as to optimize the management of chronic HBV.

Evolving clinical landscape of chronic hepatitis B: A multicenter Italian study

The aim of the study was to evaluate the characteristics of chronic hepatitis B with special reference to the geographical origin of the patients and to the prevalence of HBeAg and viral and non-viral co-factors of liver disease. A cross-sectional multicenter survey was undertaken, which enrolled 1,386 HBsAg chronic carriers observed consecutively in 21 referral centers over a 6-month period. The prevalence of HBeAg in patients was 11%; the presence of HBeAg was associated independently with a younger age and co-infection with HIV. Anti-HDV, anti-HCV, or anti-HIV antibodies were detected in 8.1%, 6.5%, and 2%, respectively. However, among the patients first diagnosed during the study period (incident cases), 14.3% were anti-HDV positive. Seven percent of the patients were immigrants; they were younger than Italian patients and 18% were HBeAg positive; no difference was observed in the prevalence of anti-HDV, anti-HCV, or anti-HIV antibodies. The presence of cirrhosis was associated independently with an age >52 years, the presence of anti-HDV or anti-HCV, alcohol use >4 drinks/day, and a high BMI. The clinical epidemiology of chronic hepatitis B virus (HBV) infection shows a dynamic profile, with the potential for re-emergence of cases with HBeAg or anti-HDV and an emerging impact of metabolic factors on the evolution of liver disease.

Hepatitis B virus resistance to nucleos(t)ide analogues

Patients with chronic hepatitis B (CHB) can be successfully treated using nucleos(t)ide analogs (NA), but drug-resistant hepatitis B virus (HBV) mutants frequently arise, leading to treatment failure and progression to liver disease. There has been much research into the mechanisms of resistance to NA and selection of these mutants. Five NA have been approved by the US Food and Drug Administration for treatment of CHB; it is unlikely that any more NA will be developed in the near future, so it is important to better understand mechanisms of cross-resistance (when a mutation that mediates resistance to one NA also confers resistance to another) and design more effective therapeutic strategies for these 5 agents. The genes that encode the polymerase and envelope proteins of HBV overlap, so resistance mutations in polymerase usually affect the hepatitis B surface antigen; these alterations affect infectivity, vaccine efficacy, pathogenesis of liver disease, and transmission throughout the population. Associations between HBV genotype and resistance phenotype have allowed cross-resistance profiles to be determined for many commonly detected mutants, so genotyping assays can be used to adapt therapy. Patients that experience virologic breakthrough or partial response to their primary therapy can often be successfully treated with a second NA, if this drug is given at early stages of these events. However, best strategies for preventing NA resistance include first-line use of the most potent antivirals with a high barrier to resistance. It is important to continue basic research into HBV replication and pathogenic mechanisms to identify new therapeutic targets, develop novel antiviral agents, design combination therapies that prevent drug resistance, and decrease the incidence of complications of CHB.

Meta-analysis: adefovir dipivoxil in combination with lamivudine in patients with lamivudine-resistant hepatitis B virus

BACKGROUND

Currently, there are no conclusive results on the efficacy of adefovir dipivoxil (ADV) plus lamivudine (LAM) in LAM-resistant patients with chronic hepatitis B (CHB). The aim of study was to evaluate the efficacy of rescue therapy with ADV plus LAM compared to ADV monotherapy in LAM-resistant CHB patients.

RESULTS

We searched PUBMED, EMBASE, Web of Science, CNKI (National Knowledge Infrastructure), VIP database, the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews. Six eligible trials (442 patients in total) were included and evaluated for methodologic quality and heterogeneity. Greater virological response and lower emergence rate of ADV-associated mutants was observed in ADV plus LAM compared to ADV monotherapy (both P < 0.05). On the contrary, the rate of ALT normalization, HBeAg clearance and seroconversion were all similar between ADV plus LAM and ADV (all P > 0.05). Additionally, adding-on or switch-to ADV was both well tolerated.

CONCLUSION

The combination of ADV with LAM was superior in inhibiting HBV replication and preventing drug resistance as compared to ADV alone for LAM-resistant CHB patients.

Treatment of hepatitis B virus-infected patients: utility of therapeutic recommendations in developing countries

BACKGROUND

The treatment of individuals infected with hepatitis B virus (HBV) is a complex issue in practical settings, despite the explosion of new and effective antiviral agents.

OBJECTIVE

To assess the scope and limitations of ongoing treatment guidelines against HBV from a global perspective.

METHODS

Present therapeutic guidelines against HBV have been discussed with emphasis on their value in developing countries that harbor about 90% of the total number of global patients who are infected with HBV.

RESULTS/CONCLUSION

Treatment of HBV-infected patients should be appropriately followed up and healthcare delivery systems should be able to combat treatment-induced adverse side effects. Current therapeutic guidelines should be optimized based on the socio-economic conditions of developing countries.

Low pretreatment serum HBsAg level and viral mutations as predictors of response to PEG-interferon alpha-2b therapy in chronic hepatitis B

BACKGROUND

Viral genomic mutations have become increasingly recognized as being associated with the outcome of chronic HBV infection. However, the role of viral mutations as a predictor of response to pegylated-interferon (PEG-IFN) therapy has so far remained unclear.

STUDY DESIGN

Viral mutations in the enhancer II/basal core promoter (BCP)/precore and the pre-S regions were characterized by direct sequencing in pretreatment serum samples of 50 patients with chronic hepatitis B (33 HBeAg-positive and 17 HBeAg-negative), who were treated for 48 weeks with PEG-IFN alpha-2b.

RESULTS

Sustained virological response at 48 weeks post treatment, defined as HBeAg seroconversion and HBV DNA<2000IU/mL for HBeAg-positive patients, and HBV DNA<200IU/mL for HBeAg-negative patients, was achieved in 12 (36.4%) and 6 (35.3%) of HBeAg-positive and HBeAg-negative patients, respectively. Response to PEG-IFN therapy correlated to low pretreatment HBsAg level but did not correlate with HBV genotype, pretreatment alanine transaminase and HBV DNA levels. In HBeAg-positive hepatitis, PEG-IFN response correlated with the appearance of double BCP mutations (A1762T/G1764A) at baseline (P=0.041). In the HBeAg-negative group, response to PEG-IFN therapy was associated with the presence of pre-S mutation/deletions (P=0.028). Multivariate analysis identified low pretreatment HBsAg level as an independent factor associated with SVR in both groups.

CONCLUSIONS

Pretreatment quantitative HBsAg determination is useful for predicting response to PEG-IFN therapy. The presence of double BCP and pre-S mutation/deletions at entry may be associated with a high rate of antiviral response in HBeAg-positive and HBeAg-negative hepatitis, respectively.

Patterns of managing chronic hepatitis B treatment-related drug resistance: a survey of physicians in Mainland China, South Korea, Taiwan, and Thailand

PURPOSE

The emergence of antiviral resistance can negate the benefits of antiviral therapy in patients with chronic hepatitis B (CHB). This study aimed to assess how physicians in Asia manage suspected antiviral resistance.

METHODS

Randomly selected CHB-treating physicians in Mainland China, South Korea, Taiwan, and Thailand underwent a face-to-face interview. A standardized questionnaire was used to assess how physicians identify, monitor, and manage suspected resistance and its associated medical costs.

RESULTS

We interviewed 575 physicians from January to May 2008. Most physicians preferred a "prevention-of-antiviral resistance" strategy over a "rescue-once-resistance-develops" strategy. Physicians had encountered lamivudine resistance most frequently (96-100% of respondents), followed by the resistance to adefovir (18-58%) and entecavir (3-7%). While physicians in South Korea and Taiwan have access to resistance testing, physicians in Mainland China and Thailand have limited access to resistance testing but rely on HBV DNA and alanine aminotransferase (ALT) tests to identify resistance. Once resistance is suspected, 60% of the physicians in Mainland China, South Korea, and Thailand monitored these patients quarterly and the remaining 40% opted for monthly follow-up. In comparison, 70% of the Taiwanese physicians monitored these patients monthly. The average total direct medical costs, excluding antiviral costs, to manage a patient during the first year after suspected resistance is identified ranged from USD $319 to USD $709.

CONCLUSIONS

Limited access to HBV resistance tests causes physicians in Asia to manage suspected resistance by various HBV DNA assays and ALT tests. This raises concerns that resistance may not be detected early enough to be rescued efficiently.

Hepatitis B virus variants

HBV replicates through reverse transcription of an RNA intermediate; the inherent lack of proofreading causes a high mutation frequency. Mutations in the precore and core promoter regions that abolish or reduce the production of hepatitis B e antigen occur most commonly. Patients with these HBV variants remain viremic and can develop progressive liver disease. Mutations in the core promoter region are associated with an increased risk of hepatocellular carcinoma. Exogenous selection pressure might favor certain mutations. Mutations in the HBV polymerase that confer resistance to nucleoside and nucleotide analog treatments are a major barrier to the success of therapy for hepatitis B. The development of antiviral drug resistance negates the initial treatment response and can lead to hepatitis flares and hepatic decompensation. Prompt addition of another drug to which the virus is not cross-resistant is required. Mutations in the HBV surface protein that facilitate escape from host immunity are responsible for the failure of immune prophylaxis in infants who received HBV vaccine and in liver transplant recipients who received hepatitis B immune globulin.

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.

Efficacy of consensus interferon in treatment of HbeAg-positive chronic hepatitis B: a multicentre, randomized controlled trial

Background

Consensus interferon (CIFN) is a newly developed type I interferon.

Aims

This multicentre, controlled trial was conducted to determine the efficacy of CIFN and to compare it with alpha-1b-interferon (IFN-α1b) in the treatment of patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B.

Methods

144 Patients were randomly assigned to receive 9 μg CIFN (CIFN group) or 50 μg INF-α1b (IFN-alpha group) subcutaneously 3 times weekly for 24 weeks, followed by 24 weeks of observation. Efficacy was assessed by normalization of serum alanine transaminase (ALT) levels and the non-detectability of serum hepatitis B virus DNA or HBeAg at the end of treatment and 24 weeks after stopping treatment.

Results

There was no statistically significant difference in the serological, virological and biochemical parameters between CIFN and IFN-α1b groups at the end of the therapy and follow-up period (p > 0.05). Overall, at the end of treatment, 7.0% (5/71) and 35.2% (25/71) of patients in the CIFN group showed a complete or partial response compared with 7.4% (5/68) and 33.8% (23/68) of the IFN-alpha group (p = 0.10). At 24 weeks after stopping treatment, 6.9% (5/72) and 37.5% (27/72) of patients in the CIFN group showed complete response or partial response compared with 7.1% (5/70) and 34.3% (24/70) of the IFN-alpha group (p = 0.10).

Conclusion

These findings suggest that 9 μg CIFN is effective in the treatment of patients with HBeAg-positive chronic hepatitis B. It can gradually induce ALT normalization and HBV DNA clearance and HBeAg loss or HBeAg/HBeAb seroconversion.

Drug targets in hepatitis B virus infection

Hepatitis B virus infection (HBV) is a significant global health problem. Despite the success of universal hepatitis B vaccination in many countries, more than 350 million individuals worldwide are chronically infected and 15- 40% of those will develop cirrhosis and/or hepatocellular carcinoma if left untreated. Available therapies for chronic hepatitis B (CHB) infection are effective at decreasing viremia and improving measured clinical outcomes, however, no single therapy is optimal. As such, alternative drug therapies and the investigation of their role in the management of CHB are warranted. Significant improvements in the understanding of the HBV life cycle, viral genomics, and virus-host interactions continue to lead to the development of novel viral targets and immune modulators. Currently, two major classes of agents are utilized in CHB: the interferons and the nucleos(t)ide analogues. Each agent has individual advantages and drawbacks. The development of specific antiviral therapy has led to the emergence of HBV drug-resistant strains that has limited the long-term therapeutic potential of available agents. This necessitates the development of new agents that target both wild-type and drug-resistant strains. Further understanding of the basic mechanisms and clinical nuances of drug therapy is warranted. As most novel therapies are in the earliest stages of clinical development and testing, in the near future, treatment will continue to be long-term and likely involve the use of combination therapies to prevent viral resistance. In this review, we will highlight the HBV life cycle and genome, focusing in on current and potential novel antiviral drug targets as well as the benefits and clinical challenges with these therapies.

Chronic hepatitis B: who to treat and which choice of treatment?

The goal of antiviral therapy in patients with chronic hepatitis B is to prevent, through persistent suppression of HBV replication, cirrhosis and hepatocellular carcinoma. Currently, seven drugs are available: IFN-alpha, pegylated interferon, lamivudine, adefovir dipivoxil, entecavir, telbivudine and tenofovir. The choice of the drugs should always take into consideration the clinical features of patients, the antiviral efficacy of each drug, the risk of developing resistance, the long-term safety profile, the method of administration and the cost of therapy. Ideal candidates for treatment are hepatitis B e antigen-positive patients with a prolonged phase of immune clearance and hepatitis B e antigen-negative patients with elevated levels of serum HBV DNA, abnormal alanine aminotransferase and histologic evidence of moderate or severe liver necroinflammation and/or fibrosis. Patients with compensated or decompensated cirrhosis should be treated, even if alanine aminotransferase levels are normal and/or serum HBV DNA levels are low, in order to prevent disease flare and to improve liver function.

Rapid HBV DNA decrease (week 12) is an important prognostic factor for first-line treatment with adefovir dipivoxil for chronic hepatitis B

BACKGROUND

The aim of the study was to estimate the effect of viral factors (HBV genotype, viral load and kinetics) to treatment response in chronic hepatitis B (CHB) and first-line therapy with adefovir dipivoxil (ADV).

METHODS

Sixty-six patients (60% males, 65% HBeAg negative) were treated with 10 mg ADV QD. Quantitative HBV DNA and ALT levels were determined at weeks 4, 12, 24, 48, 72 and 96. Nonresponse or viral resistance to ADV was assessed in patients with either persistent elevated HBV DNA levels (week 24) or with an increase in HBV DNA of at least 1 log after initial decline.

RESULTS

Most patients were infected with genotype D (66.7%; genotype A: 27.3%; genotype E: 6%); 86.4% achieved a virological (VR) and 54.5% a biochemical response (BR) in week 48, more often in patients with genotype A (P < 0.01). In week 96, BR increased to 60.5%, whereas a negative HBV DNA was observed in 83.3%. In 3% an ADV-induced viral resistance was detected. As an important predictive parameter for VR, a rapid decline of viral load at week 12 was observed. Of the patients with a negative PCR or drop of viral load of at least 3 log, 96% were still HBV DNA negative at the end of week 96; 77% of patients with a partial response achieved a VR. In contrast, no patient with nonresponse (week 12) reached a negative PCR at week 96 (P < 0.0001).

CONCLUSIONS

These results underline the importance of early viral kinetics to assess treatment response in CHB. In ADV nonresponders (week 12), an advanced antiviral therapy or switch to another nucleoside analogue should be considered.

Impact of hepatitis B virus genotypes and surface antigen variants on the performance of HBV real time PCR quantification

Quantitative PCR assays used to monitor hepatitis B virus (HBV) load differ in their ability to detect different HBV variants. This study evaluated the performance of the Abbott RT PCR assay for quantitating DNA from different HBV genotypes and from HBV variants bearing HBsAg gene mutations. The study was performed on a randomly-selected sample with a viral load >6logIU/mL for each genotype and on 25 HBsAg variants. Each sample was assayed using the Abbott RT assay and with the Roche Cobas AmpliPrep-Cobas TaqMan as a reference method. All HBV genotypes were detected with the Abbott RT assay with an equivalent dynamic range (1-8logIU/mL). For each genotype, the data suggest that the assay was linear over the entire dilution range (r(2): 0.985-0.995). For the 25 HBsAg variants, viral titres determined with the two assays correlated well (r(2): 0.929). The mean difference between the two methods was -0.295 (95% CI: -0.520 to -0.071). The difference was lower than 1log unit in all but two cases. In conclusion, the Abbott RT assay can detect and quantify DNA from different HBV variants with equivalent performance and is thus suitable for routine monitoring of patients with chronic HBV infections.

Long-term monitoring shows hepatitis B virus resistance to entecavir in nucleoside-naïve patients is rare through 5 years of therapy

Patients with chronic hepatitis B virus (HBV) infection who develop antiviral resistance lose benefits of therapy and may be predisposed to further resistance. Entecavir (ETV) resistance (ETVr) results from HBV reverse transcriptase substitutions at positions T184, S202, or M250, which emerge in the presence of lamivudine (LVD) resistance substitutions M204I/V +/- L180M. Here, we summarize results from comprehensive resistance monitoring of patients with HBV who were continuously treated with ETV for up to 5 years. Monitoring included genotypic analysis of isolates from all patients at baseline and when HBV DNA was detectable by polymerase chain reaction (> or = 300 copies/mL) from Years 1 through 5. In addition, genotyping was performed on isolates from patients experiencing virologic breakthrough (> or = 1 log(10) rise in HBV DNA). In vitro phenotypic ETV susceptibility was determined for virologic breakthrough isolates, and for HBV containing novel substitutions emerging during treatment. The results over 5 years of therapy showed that in nucleoside-naïve patients, the cumulative probability of genotypic ETVr and genotypic ETVr associated with virologic breakthrough was 1.2% and 0.8%, respectively. In contrast, a reduced barrier to resistance was observed in LVD-refractory patients, as the LVD resistance substitutions, a partial requirement for ETVr, preexist, resulting in a 5-year cumulative probability of genotypic ETVr and genotypic ETVr associated with breakthrough of 51% and 43%, respectively. Importantly, only four patients who achieved < 300 copies/mL HBV DNA subsequently developed ETVr.

CONCLUSION

Long-term monitoring showed low rates of resistance in nucleoside-naïve patients during 5 years of ETV therapy, corresponding with potent viral suppression and a high genetic barrier to resistance. These findings support ETV as a primary therapy that enables prolonged treatment with potent viral suppression and minimal resistance.

Hepatitis B: the virus and disease

Hepatitis B virus (HBV) infects more than 300 million people worldwide and is a common cause of liver disease and liver cancer. HBV, a member of the Hepadnaviridae family, is a small DNA virus with unusual features similar to retroviruses. HBV replicates through an RNA intermediate and can integrate into the host genome. The unique features of the HBV replication cycle confer a distinct ability of the virus to persist in infected cells. Virological and serological assays have been developed for diagnosis of various forms of HBV-associated disease and for treatment of chronic hepatitis B infection. HBV infection leads to a wide spectrum of liver disease ranging from acute (including fulminant hepatic failure) to chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Acute HBV infection can be either asymptomatic or present with symptomatic acute hepatitis. Most adults infected with the virus recover, but 5%-10% are unable to clear the virus and become chronically infected. Many chronically infected persons have mild liver disease with little or no long-term morbidity or mortality. Other individuals with chronic HBV infection develop active disease, which can progress to cirrhosis and liver cancer. These patients require careful monitoring and warrant therapeutic intervention. Extrahepatic manifestations of HBV infection are rare but can be difficult to diagnose and manage. The challenges in the area of HBV-associated disease are the lack of knowledge in predicting outcome and progression of HBV infection and an unmet need to understand the molecular, cellular, immunological, and genetic basis of various disease manifestations associated with HBV infection.

Antiviral resistance and hepatitis B therapy

The management of chronic hepatitis B currently rests with long-term therapy using oral nucleoside analogs. The major limitation of long-term therapy is antiviral resistance. Antiviral resistance is due to the high rate of mutations that can occur during hepatitis B virus (HBV) replication and the selection of these mutants due to a replication advantage in the presence of the antiviral agent. Indeed, high rates of antiviral resistance have been found with long-term use of lamivudine, in up to 76% of patients treated for 5 years or more. Rates of antiviral resistance are lower with adefovir therapy, approximately 30% at 5 years. Newer more potent nucleoside analogs (tenofovir and entecavir) have proven to have much lower rates of antiviral resistance (<1% after 2 years in treatment-naïve subjects), but the long-term rates of resistance have yet to be fully defined. The appearance of these viral mutations (genotypic resistance) is usually followed by rises in HBV DNA levels (virological breakthrough) and then by rises in serum aminotransferase levels (biochemical breakthrough). The appearance of antiviral resistance can be accompanied by a transient but occasionally severe exacerbation of the underlying liver disease which in some instances has led to acute liver failure. Combinations of nucleoside analogs may offer an approach to preventing antiviral resistance, but the efficacy and safety of this approach have yet to be shown. A future research priority is to identify new agents active against HBV that target different steps in the viral life-cycle and might provide effective means to circumvent the antiviral resistance of nucleoside analogs.

Monitoring during and after antiviral therapy for hepatitis B

Recent studies suggest that long-term suppression of viral replication is critical to reducing the complications of chronic hepatitis B virus (HBV) infection. Monitoring for continued virological response during and after treatment is essential because current treatment options have limited success in achieving durable endpoints, and antiviral resistance may emerge during long-term therapy. Methods of monitoring treatment response include tests for serum aminotransferase levels, HBV DNA level, hepatitis B e antigen (HBeAg) and antibody (anti-HBe), hepatitis B surface antigen (HBsAg) or antibody (anti-HBs), and liver histology. Virological suppression and loss of HBeAg or HBsAg with or without seroconversion play a prominent role in decision-making regarding the success and duration of antiviral therapy. Guidelines recommend that testing for serum markers be repeated every 12-24 weeks during antiviral therapy and every 6-12 months afterward. Recent data also suggest that serum HBV DNA levels should be assessed at weeks 12 and 24 of therapy, because early viral response may predict the likelihood of sustained response and antiviral resistance. The use of serum HBV DNA levels for this purpose requires an assay with a wide range of quantification, such as real-time polymerase chain reaction assays, which have a 7-8 log(10) dynamic range. Newer, investigational methods for monitoring treatment response include quantitative measurement of HBsAg, HBeAg, and intrahepatic covalently closed circular DNA.

CONCLUSIONS

Better methods for defining durable treatment endpoints are needed. Other areas requiring further research include the optimal treatment duration and the establishment of the optimal use of early viral kinetics for decision-making during antiviral therapy.

Early changes of hepatitis B virus quasispecies during lamivudine treatment and the correlation with antiviral efficacy

BACKGROUND/AIMS

To investigate dynamic changes of hepatitis B virus (HBV) quasispecies within the reverse transcriptase (RT) region during the early stage of lamivudine treatment and the correlation with antiviral efficacy.

METHODS

Twenty-five chronic hepatitis B patients received lamivudine treatment for 48 weeks. Fourteen patients responded to lamivudine, while eleven patients were non-responders. HBV DNA was extracted from serum samples at baseline and week 4. The RT region of HBV was amplified, then cloned and sequenced. Quasispecies complexity and diversity within the RT region were analyzed at baseline and week 4, and viral nucleotide substitution rates during the first 4 weeks were calculated.

RESULTS

The quasispecies complexity and diversity were not different between responders and non-responders at baseline (p>0.05). However, the quasispecies complexity and diversity of responders were significantly lower than those of non-responders at week 4 (p<0.01). Furthermore, the viral nucleotide substitution rate of responders was significantly higher than that of non-responders (p<0.05).

CONCLUSIONS

The dynamic changes of HBV quasispecies within the RT region showed distinct patterns between responders and non-responders during early stage of lamivudine treatment. The dynamic changes of quasispecies complexity and diversity during the first 4 weeks were correlated with lamivudine antiviral efficacy and antiviral resistance.