Factors associated with hepatitis B virus DNA breakthrough in patients receiving prolonged lamivudine therapy

Managing hepatitis B/HIV co-infected: adding entecavir to truvada (tenofovir disoproxil/emtricitabine) experienced patients

BACKGROUND

Combination emtricitabine (FTC) or lamivudine (LAM) with tenofovir disoproxil (TDF) is the recommended first-line regime for treatment in chronic hepatitis B virus (HBV)/HIV co-infection. However, in those failing to suppress, few data exist regarding further management. In HBV/HIV co-infection, there are no published data describing outcomes when entecavir (ETV) is then added to TDF-based regimes in patients no longer suppressing their HBV. We report the first series of patients using ETV with truvada-based HAART in HBV/HIV co-infected patients with previous HBV therapy failure, including inadequate suppression.

METHODS

A prospective observational study.

RESULTS

Thirteen HIV/HBV co-infected patients (all male, hepatitis B e antigen positive and hepatitis B e antibody negative) were commenced on ETV in addition to background truvada. All patients were previously exposed to LAM or FTC and TDF (median 53 months, range 6−123). Seven patients had LAM monotherapy prior to TDF/LAM or FTC combination; the remaining six patients were exposed to FTC or LAM and TDF combination. Median time of follow-up was 74 weeks (range 16−159) and median HBV decline was 2.53 log(10) IU/ml (range 1.28−7.36). Thirty-eight percent of patients achieved undetectable HBV DNA level by the end of the study and eight of 13 (62%) achieved normal alanine aminotransferase (ALT) levels with median reduction −28 U/l (range −152 to 37). TDF was stopped in one patient because of renal toxicity. ETV was well tolerated with no change of estimated glomerular filtration rate during the study.

CONCLUSION

Entecavir can be considered in addition to TDF/FTC in HBV/HIV co-infected treatment-experienced patients failing to fully suppress their HBV viral load.

Hepatitis B therapy

The goal of hepatitis B treatment is to prevent cirrhosis, liver decompensation and hepatocellular carcinoma. In clinical practice, treatment response is determined by suppression of serum HBV DNA levels, hepatitis B e antigen seroconversion to hepatitis B e antibody, hepatitis B surface antigen loss, normalization of alanine aminotransferase levels and improvement in liver histology. Patients with life-threatening liver disease, and those with high levels of HBV replication and active or advanced liver disease, should be treated. Other patients should be monitored so that treatment can be initiated when indicated. Currently, seven medications are approved for the treatment of hepatitis B: two formulations of interferon and five nucleos(t)ide analogues. Interferon is administered for a finite duration while nucleos(t)ide analogues are usually administered for many years. Antiviral drug resistance is a major limiting factor to the success of nucleos(t)ide analogue treatment; therefore, treatment should be initiated with drugs that have a high genetic barrier to resistance (that is, a low potential for drug resistance). In addition, treatment response should be closely monitored to detect virologic breakthroughs, and the importance of medication adherence should be emphasized. Management of patients with treatment failure should be tailored according to the type of treatment failure (lack of initial response versus virologic breakthrough), the treatment that the patient is receiving, history of prior treatment, and the pretreatment characteristics of both the patient and the disease.

Efficacy and safety of prolonged 3-year telbivudine treatment in patients with chronic hepatitis B

BACKGROUND

In the GLOBE trial, telbivudine demonstrated superior efficacy to lamivudine at 2 years in patients with chronic hepatitis B (CHB).

AIMS

To investigate the long-term efficacy and safety of telbivudine in the telbivudine-treated cohort from the GLOBE trial.

METHODS

Virological and biochemical responses were assessed in 213 HBeAg-positive and 186 HBeAg-negative CHB patients who continued telbivudine treatment for 3 years.

RESULTS

Undetectable hepatitis B virus DNA and HBeAg seroconversions were achieved by 77 and 37% of HBeAg-positive patients respectively. Cumulative HBeAg seroconversion rate was 46%. HBeAg seroconversion was sustained at 52 weeks off therapy in 84% of the patients enrolled in the off-treatment follow-up arm of the study. Undetectable viraemia and normal alanine aminotransferase (ALT) levels at 3 years were achieved by 85 and 83% of HBeAg-negative patients respectively. Genotypic resistance rates for the study population who continued therapy during the third year were 11.3 in HBeAg-positive and 6.5% in HBeAg-negative patients. Patients with undetectable viraemia at treatment week 24 had optimal outcomes at 3 years. In the HBeAg-positive population, cumulative HBeAg seroconversion occurred in 58%. Resistance rates for HBeAg-positive and HBeAg-negative patients were 3.6 and 6.2% respectively. The telbivudine safety profile during prolonged therapy was similar to that in the GLOBE trial.

CONCLUSIONS

Three years of telbivudine treatment yielded high rates of viral suppression and ALT normalization with a favourable safety profile. High rates of HBeAg seroconversion were achieved with prolonged telbivudine therapy and were sustained in the majority of patients over 52 weeks off therapy.

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.

Randomized trial of lamivudine versus entecavir in entecavir-treated patients with undetectable hepatitis B virus DNA: outcome at 2 Years

We aimed to determine the 2-year outcomes of entecavir followed by lamivudine in patients with undetectable viral load (<12 IU/mL) and normal alanine aminotransferase (ALT) after initial entecavir treatment for at least 6 months. Patients were randomly assigned 1:1 to continue with entecavir or switch to lamivudine. Liver biochemistry and hepatitis B virus (HBV) DNA were determined at weeks 0, 4, 12, 24, 48, 72, and 96. Mutational analysis using line-probe assay were performed at weeks 0, 24, 48, and 96 and at the time of HBV DNA relapse. There was no elevation of ALT observed in any patients up to 96 weeks. At 96 weeks of follow-up, 19/25 (76%) patients in the lamivudine arm had persistently undetectable HBV DNA, compared with 25/25 (100%) patients in the entecavir arm. Six patients in the lamivudine arm had HBV DNA >20 IU/mL, occurring at a range of 12 to 96 weeks. Of these, four patients had HBV DNA of less than 100 IU/mL during rebound (three had undetectable HBV DNA after switching back to entecavir), and the remaining two patients had HBV DNA levels of 7,973 and 699 IU/mL. Three patients (12%) had evidence of drug-resistant mutations, of which two patients had rtM204I mutation and one patient had rtM204V mutation. One of these three patients had previous lamivudine exposure before entecavir treatment and one patient had questionable drug compliance.

CONCLUSION

Sequential therapy using entecavir followed by lamivudine resulted in virological rebound in 24% of patients after 96 weeks. Prior optimal viral suppression with entecavir did not confer any significant advantage in patients who switched to lamivudine.

The level of HBV DNA at month 12 is an important predictor of virological breakthrough during adefovir monotherapy in chronic hepatitis B patients with lamivudine resistance

BACKGROUND AND AIMS

The aim of this study was to determine the optimal time and HBV DNA levels during the treatment period for prediction of virological breakthrough (VBT) 3 years after adefovir monotherapy in chronic hepatitis B (CHB) patients with lamivudine resistance.

METHODS

We consecutively analyzed HBV DNA levels within 12 months in 210 lamivudine-resistant CHB patients treated with adefovir monotherapy for more than 36 months.

RESULTS

VBT, genotypic adefovir mutations, and virologic responses were observed in 52 (24.8%), 37 (17.6%), and 117 (55.7%) cases within 3 years of treatment, respectively. Using receiver-operating characteristic curve analysis, HBV DNA levels at month 12 had a greater power (AUROC, 0.839; 95% CI, 0.759-0.919; p<0.001) to predict VBT after 3 years of treatment. The best cut-off value of HBV DNA levels at month 12 for predicting VBT at 3 years of treatment was 200 IU/ml with a sensitivity and negative predictive value of 88.5 and 94.3%, respectively. Using this time and cut-off value, VBT had developed in six (5.7%) of the patients with HBV DNA levels<200 IU/ml (n=105) and 46 (43.8%) of the patients with HBV DNA levels≥200 IU/ml (n=105) at month 12 (p<0.001). Moreover, virological response or HBeAg seroconversion remained higher at 82.9 and 81.2%, respectively.

CONCLUSIONS

In patients who were switched to adefovir monotherapy as rescue therapy for lamivudine resistance before the introduction of current therapeutic guidelines, measurements of HBV DNA levels at month 12 should be performed to predict VBT. Early termination of adefovir monotherapy should be considered for patients who still have HBV DNA≥200 IU/ml (3 log10 copies/ml) at 12 months of treatment.

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

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

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

BACKGROUND

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

AIM

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

METHODS

A comprehensive literature search was undertaken.

RESULTS

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

CONCLUSIONS

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

Safety evaluation of telbivudine

IMPORTANCE OF THE FIELD

Successful treatment of chronic hepatitis B (CHB) often requires long-term oral nucleoside/nucleotide agents which can be associated with viral resistance, patient non-compliance and adverse effects. Telbivudine is one of the more potent options available, with a 6.5- to 6.6-log copies/ml hepatitis B DNA reduction at 12 weeks in an early viral kinetic study, a potency comparable to entecavir. It is also one of the few drugs in the treatment of CHB under FDA pregnancy Category B.

AREAS COVERED IN THIS REVIEW

The efficacy and safety profile of telbivudine in compensated and decompensated CHB patients compared to other agents are discussed. Viral resistance, characteristic adverse effects including elevation in creatine kinase and peripheral neuropathy in telbivudine treatment are reviewed. Infrequent but significant adverse effects of other nucleoside/nucleotide analogs are highlighted.

WHAT THE READER WILL GAIN

Readers are provided the latest update on the clinical profile of long-term use of telbivudine.

TAKE HOME MESSAGE

Long-term telbivudine treatment offers effective viral suppression to CHB patients with certain baseline characteristics and on-treatment virologic response. Creatine kinase elevation is not a good predictor of muscle-related adverse effects with nucleoside/nucleotide analogs. But significant myopathy and neuropathy have been reported in a small number of patients receiving telbivudine.

Antiviral drugs for HBV liver disease

INTRODUCTION

Chronic hepatitis B (CHB) virus infection affects about 400 million people around the globe and is among the world's leading causes of death. The management of CHB has evolved rapidly, several therapeutic options are now available to prevent both progression of liver disease and anticipated liver morbidity and mortality.

AREAS COVERED

Current treatment modalities for CHB patients, together with suggestions from our own experience are summarized. The most relevant works published in recent years on pegylated interferon, nucleos(t)ides analogues (NUC) and the 2009 update of the American Association for the Study of Liver Diseases Practice Guidelines and the 2009 European Association for the Study of the Liver (EASL) Clinical Practice Guidelines on the management of chronic hepatitis B are discussed.

EXPERT OPINION

Pegylated interferon and NUC have advantages and limitations, as short-term interferon treatment induces a sustained virological response in a third of patients, whereas long-term suppressive therapy by NUC rapidly inhibits HBV replication in most patients but drug resistance and safety in the long-term will remain the most important unresolved questions. Careful evaluation of patient history, staging of liver disease and virological factors should guide the start of treatment and the choice to the most appropriate individualized treatment strategy in all CHB patients.

A comparison of 48-week treatment efficacy between clevudine and entecavir in treatment-naïve patients with chronic hepatitis B

PURPOSE

Clevudine and entecavir are currently available in Korea as antiviral drugs against chronic hepatitis B (CHB). We aimed to compare the efficacy of clevudine and entecavir therapy.

METHODS

Treatment-naïve CHB patients who received 30 mg of clevudine or 0.5 mg of entecavir a day were analyzed. Mean reduction of hepatitis B virus (HBV) DNA levels, complete virological response (cVR, undetectable HBV DNA by real-time PCR), biochemical response (recovery to normal ALT level), and hepatitis B e antigen (HBeAg) seroconversion rate at the 48th week of treatment were assessed.

RESULTS

A number of 59 patients in clevudine group and 61 patients in entecavir group were included. Mean HBV DNA reductions from baseline were similar in the clevudine and entecavir groups, -6.4 versus -6.8 log(10) copies/mL in HBeAg-positive (p = 0.417) and -6.9 versus -7.0 log(10) copies/mL in HBeAg-negative patients (p = 0.640). The proportion of patients who achieved cVR was not different between the two groups, 53 versus 55% in HBeAg-positive (p = 1.000) and 100 versus 95% in HBeAg-negative patients (p = 0.452). Biochemical response rates and HBeAg seroconversion rates were also similar in both the groups. Two (3.4%) patients in clevudine group showed virologic breakthrough with rtM204I mutation using direct sequencing analysis. Clinical myopathy occurred in two (3.4%) patients in clevudine group.

CONCLUSION

Mean reduction of viral loads was similar between clevudine and entecavir groups during 48 weeks. However, virologic breakthrough and significant myopathy were noted only in clevudine-treated patients. Therefore, more attention should be paid to patients receiving clevudine.

Treatment of HBeAg-negative chronic hepatitis B patients with nucleos(t)ide analogues

Current agents used in the treatment of chronic hepatitis B (CHB) can be classified into interferons-α (IFN-α: standard or pegylated) and nucleos(t)ide analogues (NUCs). NUCs are now used in most CHB patients for several reasons. They can be given to all CHB patients, even those with contraindications to IFN-α. NUCs are more convenient to use (one oral tablet daily) than IFN-α (subcutaneous injections) and are well tolerated with a good safety profile, while IFN-α has frequent and potentially severe side effects and worsens the patient's quality of life. All NUCs are potent anti-hepatitis B virus agents (all but adefovir are more potent than IFN-α) with entecavir(ETV) and tenofovir offering the highest potency and most importantly minimal to negligible risk of resistance during long-term monotherapy [corrected]. Prolongation of entecavir or tenofovir monotherapy maintains and slightly increases the initially high virological remission rates (67-76% of HBeAg-positive and 90-93% of HBeAg-negative patients) and this is expected to result in improved long-term outcomes. The need for long-term, perhaps indefinite, treatment is the main limitation of NUCs and the finite duration (48 weeks) the main advantage of IFN-α. However, only a minority of IFN-α-treated patients achieve durable sustained off-treatment responses (HBeAg-positive: 30-35%, HBeAg-negative: 20-25%), while NUCs may be safely discontinued in HBeAg-positive patients with stable HBeAg seroconversion. Because there will always be concerns for safety and family planning issues with long-term therapy, NUCs should be used judiciously and should not be prescribed in young CHB patients with mild liver disease.

Treatment of chronic hepatitis B: Evolution over two decades

There has been a recent paradigm shift in the indications and endpoints of treatment for chronic hepatitis B (CHB). Hepatitis B e antigen (HBeAg)-negative disease is being increasingly recognized. Antiviral treatment for both HBeAg-positive and HBeAg-negative patients should aim at long-term suppression of HBV DNA, with the ultimate ideal endpoint of hepatitis B surface antigen (HBsAg) seroconversion. Conventional interferon alpha (IFN-α), the only agent licensed in 1991, has been superseded by pegylated IFN-α. HBeAg seroconversion using pegylated IFN-α is 33%, with only 25% of HBeAg-positive patients achieving undetectable HBV DNA by polymerase chain reaction (PCR) assay. Five nucleoside/nucleotide analogues have been licensed since 1998. Lamivudine, an L-nucleoside, is limited by the development of resistance in 76% of patients after 5 years of therapy. Telbivudine, another L-nucleoside, is more potent than lamivudine but resistance still develops in 25% of HBeAg-positive and 11% HBeAg-negative patients after 2 years. Adefovir, an acyclic phosphonate, is relatively weak, but is effective against lamivudine- and telbivudine- resistant mutations, for which it should be used in combination (add-on therapy) rather than substituted. Resistance to adefovir develops slowly, rising to 29% for HBeAg-negative patients by year 5, but more rapidly when used alone for lamivudine-resistant HBV. Currently the two first line nucleoside/nucleotides are entecavir and tenofovir. Entecavir, a cyclopentane (D-nucleoside), is very potent, with 94% of patients having undetectable HBV DNA after 5 years. Resistance develops in only 1.2% of treatment-naïve patients. Tenofovir, another acyclic nucleotide, is more potent with less renal toxicity compared to adefovir. It is effective against lamivudine-resistant mutations when used alone. No resistance to tenofovir has been described after its use for 3 years or longer, often for patients with human immunodeficiency virus/HBV co-infection. With these current, potent antiviral agents associated with very low rates of resistance, long-term HBV DNA suppression and possibly even reversal of cirrhosis can now be achieved in a proportion of patients. In addition, long-term treatment with these antiviral agents is associated with a reduced risk of development of hepatocellular carcinoma.

HBV therapy: guidelines and open issues

Therapy of chronic hepatitis B is currently based on two different strategies: (a) a finite course of treatment with pegylated interferon aimed to induce a sustained virological response that is maintained long-term after therapy withdrawal and (b) an indefinite treatment with oral anti-HBV nucleoside/nucleotide analogues (NUCs) aimed to achieve long-term complete suppression of HBV replication. The first strategy is typically used in patients with less advanced liver disease, with high ALT and no too high HBV-DNA and is particularly successful in the younger patients and in those infected with HBV genotype A or B. The suppressive strategy is instead typically adopted for patients with more advanced liver disease, and for those who have failed or cannot tolerate interferon therapy. Recently, following the implementation of third generation NUCs with high antiviral potency and barrier to resistance, the indication of oral therapy has gained credibility and indication, although most guidelines still recommend to start these drugs only in the presence of significant and progressive liver disease. This review summarises the recent Recommendations produced for the treatment of chronic HBV infection, with particular focus on the 2010 Italian Guidelines.

Hepatitis B virus resistance to antiviral drugs: where are we going?

Chronic hepatitis B virus (HBV) infections remain a major public health problem worldwide. According to World Health Organization estimates, more than 300 million people are chronically infected and exposed to the risk of developing severe complications including cirrhosis and hepatocellular carcinoma (HCC). Major progress in the treatment of chronic hepatitis B (CHB) has been made during the last decade with the development of antivirals that inhibit viral polymerase activity. Antiviral drug resistance is an important factor in determining the success of long-term therapy for CHB. The development of resistance to nucleoside analogues (NUCs) has been associated with exacerbations of liver disease. Sequential therapy increases the risk of the emergence of multidrug resistance. The selection of a potent antiviral with a high barrier to resistance as a first-line therapy provides the best chance of achieving long-term treatment goals and should be used whenever possible. This has led to a significant decrease in drug resistance in countries where this strategy is affordable. However, the barrier to resistance of a given antiviral agent is influenced by the genetic barrier, drug potency, patient adherence, pharmacological barrier, viral fitness, the drug mechanisms of action and cross resistance. Furthermore, because of specific viral kinetics, prolonged treatment with NUCs does not result in the clearance of the viral genome from the infected liver. It is therefore important to continue research to identify new viral and immune targets and develop novel antiviral strategies for controlling viral replication as well as preventing drug resistance and its complications in the long term.

A low viral load predicts a higher initial virologic response to adefovir in patients with Lamivudine-resistant chronic hepatitis B

BACKGROUND/AIMS

Adefovir (ADV) is the preferred drug for treating lamivudine (LAM)-resistant hepatitis B. However, not all patients who face virologic breakthrough during LAM treatment respond to ADV. The aim of this study was to determine the factors associated with efficacy of ADV in LAM-resistant hepatitis B patients.

METHODS

The medical records of 231 patients who received ADV due to LAM-resistance were reviewed. Efficacy was assessed by the initial virologic response (IVR), defined as hepatitis B virus (HBV) DNA not being undetectable by real-time PCR at 6 months of ADV treatment.

RESULTS

Seventy patients (30%) achieved IVR. While 'add-on' modality, hepatitis B e antigen (HBeAg) negativity, and low baseline HBV DNA levels were associated with IVR in univariate analysis, multivariate analysis revealed HBeAg status and the DNA level to be the significant factors. The probability of IVR achievement increased sharply per each log(10) copies/mL decrement in the baseline viral load, which was 133 times in patients who had HBV DNA <10(5) copies/mL compared with those who had ≥10(8) copies/mL.

CONCLUSIONS

Factors associated with the IVR were HBeAg negativity and a low baseline viral load. Therefore, when virologic breakthrough with genotypic resistance emerges during LAM therapy, ADV treatment should be considered immediately before further increases in viral load. Additional long-term follow-up data are warranted.

Efficacy of tenofovir disoproxil fumarate/emtricitabine compared with emtricitabine alone in antiretroviral-naive HIV-HBV coinfection in Thailand

BACKGROUND

Therapy for chronic hepatitis B with tenofovir disoproxil fumarate (TDF) and lamivudine (3TC) or emtricitabine (FTC) is currently recommended for HIV-HBV coinfection. However, there is limited randomized data on the efficacy of combined therapy with TDF and FTC, especially in antiretroviral (ARV)-naive patients.

METHODS

This was a prospective randomized clinical trial comparing the efficacy of HBV monotherapy with FTC versus TDF/FTC combination therapy in ARV-naive HIV-HBV coinfection. HIV-HBV-coinfected patients initiating ARV were randomized to either FTC/zidovudine/efavirenz (EFV; n=6) or TDF/FTC/EFV (n=10). The primary end point was the time-weighted area under the curve (TWAUC) of HBV DNA at 48 weeks.

RESULTS

The median baseline CD4(+) T-cell count was 64 cells/μl (interquartile range [IQR] 36-172), plasma HIV type-1 RNA was 4.90 log(10) copies/ml (IQR 4.58-5.44) and plasma HBV DNA was 8.76 log(10) copies/ml (IQR -8.45-8.82). A total of 11/16 (69%) patients were hepatitis B e antigen (HBeAg)-positive. The median TWAUC decrease in HBV DNA was -5.32 log(10) copies/ml in the TDF/FTC group compared with -3.25 log(10) copies/ml in the FTC group (P=0.03). At week 48, 90% of the TDF/FTC group and 33% of the FTC group had plasma HBV DNA<170 copies/ml (P=0.036, intention-to-treat analysis). HBeAg loss was observed in 4/11 (36%) HBeAg-positive patients. Hepatic flares were observed in 3/16 (19%) of patients.

CONCLUSIONS

TDF/FTC combination therapy resulted in a significantly greater decrease in HBV DNA than FTC monotherapy, with a greater proportion of patients with undetectable HBV DNA at week 48. Our study supports the current recommendation of ARV containing TDF/FTC as the treatment of choice for patients with HIV-HBV coinfection.

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.

Lamivudine plus adefovir or entecavir for patients with chronic hepatitis B resistant to lamivudine and adefovir

BACKGROUND & AIMS

Little is known about the optimal management of patients with chronic hepatitis B (CHB) who developed multiple-drug resistance.

METHODS

We assessed 91 patients with compensated CHB who developed adefovir-resistant mutations during adefovir monotherapy for lamivudine-resistant CHB. Of these, 41 were treated with a combination of lamivudine plus adefovir (LAM+ADV group) and 50 were treated with entecavir monotherapy (ETV group).

RESULTS

There were no significant differences between the two groups in baseline characteristics, including serum HBV DNA levels (p>0.05). The rate of virologic non-response (HBV DNA reduction <1 log(10) IU/ml at 6 months) was significantly greater in the LAM+ADV than in the ETV group (51.2% vs. 16.0%, p<0.01). At 12 months, HBV DNA declined less in the LAM+ADV than in the ETV group (-1.49+/-1.78 vs. -3.47+/-2.13 log(10) IU/ml, p<0.01). Only 12.2% and 22.0% of patients in the LAM+ADV and ETV groups, respectively, achieved complete virologic response (HBV DNA <60 IU/ml) at 12 months. Multivariable analysis showed that LAM+ADV group (OR=0.08, CI=0.02-0.28) and the presence of the rtA181V/T mutation (OR=0.21, CI=0.05-0.91) were independently associated with a decreased rate of virologic response (HBV DNA <2000 IU/ml) at 12 months.

CONCLUSIONS

In patients with CHB resistant to lamivudine and adefovir, combination therapy with these two drugs was not effective and was inferior to entecavir monotherapy in suppressing HBV DNA. However, the response to entecavir monotherapy was also not optimal. These results emphasize the importance of preventing the development of multidrug-resistant HBV and of exploration for adequate combination therapy in treatment of multidrug-resistant CHB.

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.

A Review of Oral Antiretroviral Therapy for the Treatment of Chronic Hepatitis B

Objective:

To describe the current evidence for the use of oral antiretroviral (ARV) agents in the treatment of chronic hepatitis B (CHB).

Data Sources:

A search from 1950 to April 2010 was conducted using the databases PubMed and MEDLINE with the search terms chronic hepatitis B, lamivudine, entecavir, adefovir, telbivudine, tenofovir, emtricitabine, clevudine, and pradefovir. The search was limited to trials conducted in humans that were published in the English language.

Study Selection and Data Extraction:

Studies were included if they evaluated the use of oral ARVs in patients with CHB infection who were not coinfected with hepatitis C, hepatitis D, or HIV.

Data Synthesis:

Oral ARVs have revolutionized the treatment of CHB. Studies conducted comparing ARVs have favored entecavir and tenofovir with respect to their ability to decrease hepatitis B virus DNA viral load while minimizing the development of resistance. However, low seroconversion rates, recurrent viremia when ARV therapy is discontinued, and increased resistance rates with longer treatment durations limit the benefit of oral ARVs in the treatment of CHB. Combination therapy has been a suggested solution; however, studies have yet to prove additional benefit over currently recommended monotherapy.

Conclusions:

Oral ARVs should continue to be used in the treatment of CHB; however, research is needed to define the optimal duration of therapy, evaluate the utility of combination therapy, and explore novel targets within the hepatitis B life cycle.

Virologic response at 12 months of treatment predicts sustained antiviral efficacy in patients with adefovir-treated Lamivudine-resistant chronic hepatitis B

BACKGROUND/AIMS

The aim of our study was to define the potential role of virologic response at 12 months of treatment (VR12) in predicting subsequent virologic and clinical outcomes in adefovir (ADV)-treated lamivudine-resistant chronic hepatitis B.

METHODS

Two hundred and four patients with lamivudine-resistant chronic hepatitis B virus (HBV) treated with ADV monotherapy were included. Serum HBV DNA was quantified by real-time polymerase chain reactions. VR12 was defined as a HBV DNA level of less than 4 log(10) copies/mL after 12 months of ADV treatment.

RESULTS

VR12 was observed in 110 of the 204 patients (54%). The mean HBV DNA reductions from baseline after 12 months of ADV treatment were 3.8 and 1.9 log(10) copies/mL in patients with and without VR12, respectively (p<0.001). The hepatitis B "e" antigen (HBeAg) seroconversion rates in patients with and without VR12 were 32% and 14% at 12 months treatment, respectively (p=0.018), and 40% and 27% at 24 months of treatment (p=0.032). The genotypic mutation rates to ADV in patients with and without VR12 were 0% and 6% at 12 months of treatment, respectively (p=0.033), and 21% and 42% at 24 months (p=0.012). The rates of viral breakthrough in patients with and without VR12 were 0% and 7% at 12 months of treatment, respectively (p=0.072), and 9% and 25% at 24 months (p=0.006).

CONCLUSIONS

Patients without VR12 may need to switch to or add on other potent antiviral drugs in their medical regimens.

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

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

On-treatment monitoring of chronic hepatitis B virus infection: an Asian-Pacific perspective

Chronic infection with hepatitis B virus (HBV) is a major global health problem and an important cause of morbidity and mortality from sequelae of liver cirrhosis and hepatocellular carcinoma. In the past decades, better understanding of the natural history and immunopathogenesis of chronic HBV infection and of the development of many powerful antiviral agents has allowed us to improve therapeutic efficacy. Among these agents, nucleos(t)ide analogs are important and potent viral suppressors. However, when administered alone, they are not able to permanently eradicate HBV, and long-term maintenance therapy is required for therapeutic efficacy. Additionally, prolonged treatment is frequently associated with the emergence of drug-resistant HBV mutants. Before an 'ideal' drug(s), or drug combination, with optimal antiviral efficacy and negligible rates of drug resistance becomes available, the on-treatment monitoring approach using serum HBV DNA level as a predictor for therapeutic efficacy and drug resistance is useful. However, most countries in the Asia-Pacific region have low income economies, insufficient medical care systems, and low awareness of the disease among the general population and government officers. The easy approach of the road-map concept using an affordable drug to treat chronic HBV infection is more important in this region. There is already evidence that the long-term outcomes of chronic HBV infection can be improved under well-managed antiviral therapy. Profound and long-lasting suppression of HBV replication, either maintained on-therapy or sustained after stopping therapy, has been identified as the key determinant for achieving the goals of therapy, for reducing liver damage, and for preventing development of cirrhosis and/ or hepatocellular carcinoma.

Management of chronic hepatitis B with nucleoside or nucleotide analogues: a review of current guidelines

Antiviral treatment of hepatitis B is one of the most rapidly evolving fields in current medicine. Guidelines for the management of chronic hepatitis B (CH-B) have been proposed and revised by many academic societies and groups. Recommendations for nucleoside or nucleotide analogue (NUC) therapy from representative current guidelines are compared herein with each other and with previous guidelines. Several differences among individual recommendations may reflect regional and temporal differences as well as differences in the available data upon which the guidelines are based. Nevertheless, these guidelines share a common principle regarding NUC treatment for CH-B: long-term viral suppression by the drugs with potent antiviral activity and low rate of development of drug resistance to prevent disease progression. A review of the past and current guidelines for the management of CH-B would be useful for evaluating the current status of management of the disease and to identify better solutions for improving the outcome of patients with CH-B.

Hepatitis B virus genotype B has an earlier emergence of lamivudine resistance than genotype C

BACKGROUND

Hepatitis B virus (HBV) genotype B and C seem not to affect the therapeutic response to lamivudine (3TC). Whether a given genotype has an earlier emergence of 3TC resistance remains unclear. We thus conducted this study to elucidate the association of HBV genotype with the emergence of 3TC-resistant strains in Taiwanese patients.

METHODS

Forty chronic hepatitis B patients who developed resistance after 3TC therapy were retrospectively enrolled. HBV genotype, serum alanine aminotransferase (ALT) and HBV DNA levels were determined at baseline. The presence of 3TC-resistant mutations was confirmed by direct sequencing whenever biochemical breakthrough developed.

RESULTS

The distribution of HBV genotype B and C in 40 patients receiving 3TC therapy were 60% and 40%, respectively. The mean interval to detect 3TC-resistant strain was 19.6 +/-1.7 months. By using multivariate analysis, HBV genotype B and higher pre-treatment HBV DNA level were independently associated with earlier detection of 3TC-resistant strains. In addition, genotype B was significantly associated with development of 3TC resistance within the first 12 months of 3TC therapy compared with genotype C (odds ratio 8.27; P=0.004).

CONCLUSIONS

Compared with HBV genotype C, genotype B appears to have an earlier biochemical resistance to 3TC than genotype C. Therefore, more frequent monitoring of viral load or genotypical resistance might be needed for patients with HBV genotype B infection receiving 3TC therapy, especially during the first year.

Early viral kinetics of telbivudine and entecavir: results of a 12-week randomized exploratory study with patients with HBeAg-positive chronic hepatitis B

We characterized the early viral kinetic profiles of telbivudine and entecavir and the effects of these potent nucleoside analogs on hepatitis B virus (HBV) DNA and alanine aminotransferase levels in adults with hepatitis B e antigen-positive compensated chronic hepatitis B. Forty-four patients were enrolled in this open-label, parallel-group, multicenter study and randomized to receive telbivudine or entecavir for 12 weeks. Reductions in hepatitis B virus DNA and alanine aminotransferase levels from baseline to weeks 2, 4, 8, and 12 were assessed. Viral kinetic parameters, including viral clearance per day, loss of infected cells per day, and efficiency of inhibition of viral production, were estimated by using a biphasic mathematical model. Statistical analyses were limited to descriptive analyses. The 2 treatment groups achieved similar reductions in HBV DNA and alanine aminotransferase levels. Mean reductions in levels of hepatitis B virus DNA at week 12 were 6.6 +/- 1.6 and 6.5 +/- 1.5 log(10) copies/ml for the telbivudine- and entecavir-treated patients, respectively. There were no significant differences between groups in values for mean viral clearance per day, mean loss of infected cells per day, or efficiency of blocking viral production. The safety profiles for both medications were favorable. During the first 12 weeks of treatment, telbivudine and entecavir demonstrated similar antiviral potencies, resulting in a rapid and profound suppression of serum hepatitis B virus DNA and reduction of alanine aminotransferase levels. No differences in the effects of these 2 agents on early viral kinetics were observed. Both medications were well tolerated.

HBV and HCV therapy

One year of interferon therapy inhibits HBV replication in one third of the patients whereas long-term administration of oral nucleos(t)ide analogues is efficient in most of them, as long as early treatment adaptation in patients with partial virological response and resistance is provided. Following the demonstration of a more potent antiviral effect in terms of sustained virological response (SVR) rates, Pegylated-IFN coupled with Ribavirin has become the standard treatment for chronic hepatitis C, with nearly 65% of all treated patients achieving a SVR. Long-term suppression of HBV and eradication of HCV would halt the progression of chronic hepatitis to cirrhosis, hepatocellular carcinoma and liver decompensation.

On-treatment monitoring of HBV DNA levels: predicting response and resistance to oral antiviral therapy at week 24 versus week 48

The suppression of hepatitis B viral (HBV) load correlates with favorable histologic, biochemical, and serologic responses in clinical trials of patients with chronic hepatitis B (CHB). The ability to identify patients who will not experience durable viral suppression in response to a specific antiviral regimen affords the opportunity for early treatment modification to optimize outcomes and avoid the development of antiviral resistance. Substantial evidence demonstrates that on-treatment serum HBV DNA levels are predictive of virologic response and risk of resistance. Regional clinical practice guidelines for the management of CHB universally recommend monitoring serum HBV DNA levels at treatment week 24. However, the value of this time point as a predictor of long-term success may not be applicable to all types of antiviral therapy. Indeed, each oral nucleos(t)ide analog (NA) antiviral therapy has a unique profile of potency, genetic barriers to resistance, and viral kinetics that may affect the optimal time point for on-treatment monitoring. This review discusses available data for appropriate predictors for long-term response and antiviral resistance for patients receiving specific oral NA antiviral therapy. Guidelines for on-treatment monitoring are also discussed.

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.

[Long-term clevudine therapy in nucleos(t)ide-naïve and lamivudine-experienced patients with hepatitis B virus-related chronic liver diseases]

BACKGROUNDS/AIMS

Clevudine is an effective antiviral nucleoside analogue, but there are few data regarding its long-term effects, resistance, and safety. The aim of this study was to evaluate the long-term clinical efficacy of clevudine over a 1-year treatment period in nucleos(t)ide-naive and lamivudine-experienced chronic hepatitis B patients.

METHODS

Nucleos(t)ide-naive (group A, n=196) and lamivudine-experienced (serum hepatitis B virus, HBV DNA >2,000 copies/mL without resistant mutants at the start of clevudine therapy, group B, n=75) patients were included in this study. Basic clinical characteristics including age, sex, the presence of cirrhosis, laboratory data, and hepatitis B surface antigen (HBeAg) positivity were similar between the two groups. Pretreatment serum levels of HBV DNA were 7.4 and 6.6 log(10) copies/mL (P<0.001). The mean treatment duration was 8 months for both groups (range for group A: 3-21 months; range for group B: 3-20 months). Genotypic analysis for resistant mutations in the reverse transcriptase of HBV was performed after viral breakthrough.

RESULTS

After 1 year of therapy, 75.0% and 51.9% of groups A and B, respectively, had HBV DNA levels of <2,000 copies/mL (P=0.032), and HBeAg seroconversion rates were 16.9% and 16.7%, respectively. The rates of viral breakthrough at 1 year were 10.0% (8/80) and 44.4% (12/27), respectively (P<0.001). Proven sites of mutation of HBV DNA polymerase in naive patients were, for example, L80I, L180M, A181V/T, M204I and V207I. Ten patients complained of prominent fatigue and revealed elevated serum levels of aspartate aminotransferase (AST) and creatine phosphokinase (CPK). Two of these patients presented with severe myopathy from which they recovered completely after quitting clevudine.

CONCLUSIONS

Clevudine is one of the recommended first-line medicines for the treatment of chronic hepatitis B, but it is not free from resistance, particularly in patients with a history of previous lamivudine treatment, but also in naive patients. Clevudine should be avoided in previously lamivudine-exposed patients. In addition, reelevation of serum AST and CPK levels is not a rare occurrence, and close observation and follow-up tests are essential.

Current challenges in viral hepatitis, antimicrobial resistance and the influenza pandemic

The 3rd Ditan International Conference on Infectious Diseases was held from 29 July to 2 August 2009 at the Beijing International Conference Center, Beijing, China. Over 1000 participants from 27 countries attended the 4-day conference, titled 'World Dialogue on Infectious Diseases'. A broad range of topics were covered this year, including TB, methicillin-resistant Staphylococcus aureus, HIV, influenza and gastrointestinal infections. In addition, there was a particularly strong focus on two contrasting topics of viral hepatitis and antibiotic resistance, which is the focus of this meeting report.

Efficacy of entecavir in patients with chronic hepatitis B resistant to both lamivudine and adefovir or to lamivudine alone

Entecavir (ETV) is currently recommended as a rescue therapy purely for adefovir (ADV)-resistant chronic hepatitis B virus (HBV) infections. We evaluated the efficacy of ETV in patients who were resistant to lamivudine (LAM)/ADV sequential therapy and in those resistant to LAM monotherapy. Fifty LAM/ADV-resistant and 38 LAM-resistant patients who received ETV 1 mg/day for at least 48 weeks were enrolled. Mean baseline serum HBV DNA and alanine aminotransferase (ALT) levels were significantly lower in the LAM/ADV-resistant group, compared with the LAM-resistant group (6.90 versus 7.62 log(10) copies/mL and 102.6 versus 160.2 IU/L; both P < 0.05); hepatitis B e antigen (HBeAg) status and LAM-resistant mutation patterns were similar in the two groups. At week 48, mean reductions in HBV DNA and ALT levels were significantly less in the LAM/ADV-resistant group (-2.96 versus -4.86 log(10) copies/mL and -68.3 versus -128.9 IU/L; both P < 0.05). Achievement of undetectable HBV DNA was also less common in the LAM/ADV-resistant group (10.0% versus 34.2%; P = 0.006), although the rates of HBeAg loss and ALT normalization did not differ between the two groups. Resistance to both LAM and ADV was an independent risk factor for failure of HBV DNA negativity at week 48 (odds ratio, 0.138; P = 0.019). In both LAM/ADV-resistant and LAM-resistant groups, primary responders (> or =1 log decline in HBV DNA at week 12) achieved a significantly greater decrease in HBV DNA levels over the 48-week period, compared with primary nonresponders (-4.18 versus -0.97 and -5.37 versus -2.15 log(10) copies/mL, respectively; both P < 0.05).

CONCLUSION

The 48-week ETV treatment was less effective in LAM/ADV-resistant than in LAM-resistant patients. Continuing ETV monotherapy could be determined based on the virological response at 12 weeks in LAM/ADV-resistant patients.

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.

Baseline characteristics and early on-treatment response predict the outcomes of 2 years of telbivudine treatment of chronic hepatitis B

BACKGROUND/AIMS

In the GLOBE trial, telbivudine treatment was identified as a significant, independent predictor of better outcomes at 2 years. We analyzed all telbivudine recipients in this trial to determine the predictors of optimal outcomes.

METHODS

The intent-to-treat population comprised 458 HBeAg-positive and 222 HBeAg-negative telbivudine-treated patients. Multivariate logistic regression analyses were employed to evaluate baseline and/or early on-treatment variables.

RESULTS

Baseline HBV DNA<9 log(10)copies/mL, or ALT levels > or = 2x above normal were strong pretreatment predictors for HBeAg-positive, but not for HBeAg-negative patients. However, non-detectable serum HBV DNA at treatment week 24 (TW24) was the strongest predictor for better outcomes for both groups. A combination of pretreatment characteristics plus TW24 response identified subgroups with the best outcomes: (1) HBeAg-positive patients with baseline HBV DNA<9 log(10)copies/mL, ALT > or = 2x above normal and non-detectable HBV DNA at TW24 achieved at 2 years: non-detectable HBV DNA in 89%, HBeAg seroconversion in 52%, telbivudine resistance in 1.8%; and (2) HBeAg-negative patients with baseline HBV DNA<7 log(10)copies/mL and non-detectable serum HBV DNA at TW24 achieved at 2 years: non-detectable HBV DNA in 91%, telbivudine resistance in 2.3%.

CONCLUSION

During telbivudine treatment, non-detectable serum HBV DNA at treatment week 24 is the strongest predictor for optimal outcomes at 2 years.

Combination of baseline parameters and on-treatment hepatitis B virus DNA levels to start and continue patients with lamivudine therapy

Background

This study aimed to identify the baseline hepatitis B virus (HBV) DNA, alanine aminotransferase (ALT) levels and on-treatment HBV DNA levels for favourable outcome in patients receiving 5-year lamivudine.

Methods

Virological, serological and biochemical parameters were assessed in 74 hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) patients at year 5 of therapy.

Results

Patients with baseline HBV DNA levels <9 log10 copies/ml and ALT≥2x the upper limit of normal (ULN) had a significantly higher chance of HBV DNA suppression to <4 log10 copies/ml (76.5%) and HBeAg seroconversion (82.4%), and a lower chance of YMDD mutations (35.3%) compared with patients with HBV DNA<9 log10 copies/ml and ALT<2xULN and patients with HBV DNA≥9 log10 copies/ml (all P<0.05). All patients with these two baseline parameters plus week 4 HBV DNA<4 log10 copies/ml achieved HBV DNA<35 copies/ml, HBeAg seroconversion and ALT normalization without YMDD mutations at year 5. When these two baseline parameters were combined with week 24 HBV DNA<3 log10 copies/ml, 60%, 80% and 90% of patients had HBV DNA<35 copies/ml, <3 log10 copies/ml and <4 log10 copies/ml, respectively at year 5. Overall, 90% of patients had HBeAg seroconversion and only 10% had YMDD mutations.

Conclusions

For HBeAg-positive patients with baseline HBV DNA<9 log10 copies/ml and ALT≥2xULN, lamivudine could be initiated. For those with HBV DNA<4 log10 copies/ml at week 4 or <3 log10 copies/ml at week 24, continuation of lamivudine treatment would be more likely to result in a good long-term response.

Prevention and management of drug resistance for antihepatitis B treatment

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

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.

New approaches in the management of chronic hepatitis B: role of tenofovir

In the field of HIV management, tenofovir disoproxil fumarate (TDF) plays a pivotal role and has been demonstrated to be a safe and well-tolerated antiviral agent. Recent data showed the efficacy of TDF in the treatment of chronically hepatitis B virus (HBV)-infected patients. TDF was superior to adefovir dipivoxil (ADV) in both nucleos(t)ide-naïve HBeAg-positive and HBeAg-negative HBV patients, and appeared to be one of the most potent antiviral agents so far. In addition, several reports showed that TDF was also effective in the nucleos(t)ide-experienced population, although conflicting results have been presented concerning patients with genotypic resistance to ADV. TDF seems to have a good resistance profile as well. The rtA194T mutation in association with lamivudine resistance may confer resistance to TDF, although both in vivo and in vitro studies regarding this mutation demonstrate conflicting results. As treatment with TDF may be associated with nephrotoxicity, all TDF-treated patients should be monitored for renal function at baseline and periodically thereafter. While the relative roles of interferon vs nucleos(t)ide analogues (NA) as initial anti-HBV therapy remains unclear, TDF will probably become one of the key factors in HBV management both as first-choice NA for nucleos(t)ide-naïve patients and as rescue therapy for nucleos(t)ide-experienced patients.

A short course of add-on adefovir dipivoxil treatment in lamivudine-resistant chronic hepatitis B patients

The aims of the study were to investigate the efficacy of rescue therapy with lamivudine (LAM) and adefovir (ADV) combination for 6 months followed by ADV monotherapy in lamivudine-resistant chronic hepatitis B (LAM-R CHB) patients, and to analyze the frequency of ADV resistance mutant development in such patients. A total of 170 consecutive LAM-R CHB patients (male/female: 130/40, mean age: 42.9+/-13.4 years) with viral breakthrough under LAM therapy were analyzed. A total of 68 had HBeAg-positive. Patients received rescue therapy with LAM [100 mg (qd)]+ADV [10 mg (qd)] for 6 months after which LAM was discontinued. HBV-DNA was assessed with the HBV-DNA 3.0 bDNA assay. ADV-resistant mutations were identified by sequencing the reverse transcriptase region. The median duration of rescue therapy was 24 months. Cumulative probability of becoming HBV-DNA undetectable was 33.8%, 59.6% and 68.2% after 24, 48 and 96 weeks of treatment, respectively. These figures were 43.2%, 58.0% and 73.1% for ALT normalization. Among 68 HBeAg-positive CHB patients, 10 patients had an e-antigen seroconversion. Low baseline HBV-DNA level (<10(7) copies/mL) was a significant predictor of response to ADV treatment (P<0.01). Cumulative probability of ADV resistance was 1.2%, 15.1% and 37.3% at 12, 24 and 36 months of therapy, respectively. By multivariate analysis, baseline high viral load and primary nonresponse to treatment at week 24 predicted ADV resistance. The data indicate that a time limited add-on strategy does not provide benefit over the switch strategy with respect emergence of ADV resistant mutants in LAM-R CHB patients.

Entecavir shows limited efficacy in HBeAg-positive hepatitis B patients with a partial virologic response to adefovir therapy

BACKGROUND/AIMS

We investigated the efficacy of entecavir in lamivudine-experienced and -naïve patients with persistently high HBV DNA during adefovir treatment.

METHODS

Fourteen chronic hepatitis B patients (57% lamivudine-experienced) with a viral load above 5log(10)copies/mL after 12months of adefovir therapy and thereafter were treated with entecavir 1mg daily.

RESULTS

During a median follow-up of 15months (range: 8-23months) one of six lamivudine-naïve and none of the eight lamivudine-experienced patients achieved undetectable HBV DNA (<373copies/mL). HBeAg loss occurred in none of the subjects. Two lamivudine-experienced patients demonstrated the rtM204I mutation; no other entecavir-resistant substitutions were detected (rtI169, rtT184, rtS202, and rtM250). Two of three patients with genotypic adefovir resistance at baseline demonstrated a rapid virologic response to entecavir, but undetectable HBV DNA was not achieved. To attain a better antiviral response the dosage of entecavir was increased to 2mg daily in two patients, resulting in further viral load decline for both of them.

CONCLUSIONS

Entecavir monotherapy dosed at 1mg resulted in a slow reduction of viral load in both lamivudine-experienced and -naïve patients with persistently high HBV DNA during adefovir therapy. Increasing the dosage of entecavir led to further HBV DNA decline.

Chronic hepatitis B: early viral suppression and long-term outcomes of therapy with oral nucleos(t)ides

Chronic hepatitis B is a serious health problem worldwide with a substantial minority of patients experiencing premature death due to end-stage liver disease and/or hepatocellular carcinoma. Antiviral therapy may help prevent complications of chronic hepatitis B, and seven agents are currently approved in many countries. Of these agents, five are nucleos(t)ide analogs that all have a risk of antiviral drug resistance with long-term use. Efforts have been made in the recent years to prevent or to reduce the risk of viral resistance in patients treated with oral nucleos(t)ides as the majority of these patients will require therapy for 3-5 years or longer. One approach is to identify patients who would most likely develop antiviral resistance on long-term therapy using predictors obtainable early in the course of treatment, when intervention with new or additional therapy can be instituted. The most important predictors of treatment outcomes are serum HBV DNA levels at baseline and during the first 6 months of therapy. The purpose of this synopsis is to review the recent literature regarding the importance of serum HBV DNA levels in association with treatment outcomes in chronic hepatitis B, particularly the association of complete viral suppression early in the course of oral therapy with long-term treatment outcomes, particularly the incidence of antiviral drug resistance.