Lamivudine as initial treatment for chronic hepatitis B in the United States

Antiviral therapy against chronic hepatitis B in Brazil: high rates of lamivudine resistance mutations and correlation with HBV genotypes

The effectiveness of antiviral treatments of chronic hepatitis B has been poorly studied in Brazil. Here, hepatitis B virus (HBV) DNA positivity, drug resistance mutations and their association with HBV genotypes were evaluated in chronically HBV-infected patients under different drug regimens in Brazil. The study involved 129 patients under interferon or nucleos(t)ide analogue therapy for a median treatment time of 12 months. One hundred and five (81%) of these patients were treated with lamivudine (LAM), either in monotherapy or in combination with newer drugs, such as entecavir (ETV) or tenofovir (TDF). High (37.5-100%) rates of HBV DNA positivity were observed with all but one drug regimen (LAM + ETV). However, patients that were treated with ETV alone, TDF alone or with LAM combination therapies had a mean viral load that was 3-4 log lower than patients treated with LAM monotherapy. Of the patients treated with LAM, 47% developed resistance mutations. HBV genotypes A (59.1%), D (30.3%) and F (9.1%) were found. There was no association between the presence of LAM resistance mutations and genotypes, HBeAg status or treatment duration. Nevertheless, the rtM204V mutation was observed more frequently (12/13, 92%) in genotype A than in the others (p = 0.023). Six out of nine isolates that contained the rtM204I mutation belonged to genotype D and half of them displayed a single mutation. Genotype D isolates with the rtM204V variant preferentially displayed a triple mutation, while genotype A preferentially displayed a double mutation (p = 0.04).

Long-term outcomes of add-on adefovir dipivoxil therapy to ongoing lamivudine in patients with lamivudine-resistant chronic hepatitis B

AIM

  Add-on adefovir dipivoxil (ADV) therapy has been a standard rescue treatment for patients with lamivudine (LAM)-resistant chronic hepatitis B, but the overall benefits of long-term add-on ADV therapy are still limited. The aim of this study was to evaluate the long-term efficiency of add-on ADV treatment and to explore predictive factors associated with it.

METHODS

  A total of 158 patients with LAM-resistant chronic hepatitis B were included in this retrospective, multicenter, nationwide study in Japan. After confirming LAM resistance, ADV was added to LAM treatment. Three types of events were considered as outcomes: virological response, hepatitis B e antigen (HBeAg) clearance and alanine aminotransferase (ALT) normalization. Virological response was defined as serum hepatitis B virus (HBV) DNA levels of less than 3 log copies/mL. Baseline factors contributing to these outcomes were examined by univariate and multivariate analyses.

RESULTS

  The median total duration of ADV treatment was 41 months (range, 6-84). The rate of virological response was 90.8% at 4 years of treatment; HBeAg clearance and ALT normalization were achieved by 34.0% and 82.7%, respectively, at the end of follow up. Each outcome had different predictive factors: baseline HBV DNA and albumin level were predictive factors for virological response, history of interferon therapy and ALT level for HBeAg clearance, and sex and baseline albumin level for ALT normalization.

CONCLUSION

  Long-term add-on ADV treatment was highly effective in LAM-resistant chronic hepatitis B patients in terms of virological and biochemical responses. Lower HBV replication and lower albumin level at baseline led to better outcomes.

Considerations for the long-term treatment of chronic hepatitis B with nucleos(t)ide analogs

Treatment of chronic hepatitis B (CHB) with nucleos(t)ide analogs is often required over a prolonged period to achieve durable virologic suppression. One barrier to the success of long-term therapy is the emergence of drug-resistant mutants. Current guidelines therefore recommend the most potent drugs with optimal resistance profiles, that is, entecavir and tenofovir are used as first-line monotherapies in CHB. Characteristics of the hepatitis B virus, the disease, the patient and the drug can influence the response to antiviral treatment and risk of relapse. This review discusses factors to consider maximizing the chances of successful long-term treatment of CHB, and provides an overview of the long-term efficacy and safety data that have become available over the 4-5 years since entecavir and tenofovir were first approved for the treatment of CHB. Recent findings on whether and under what circumstances long-term therapy of CHB might be stopped are also discussed.

Direct acting antivirals for the treatment of chronic viral hepatitis

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

A case of hepatitis B reactivation due to the hepatitis B virus escape mutant in a patient undergoing chemotherapy

A 62-year-old man had chronic hepatitis B virus (HBV) infection and was diagnosed with liver cirrhosis. At the time of diagnosis the patient's virologic markers were positive for hepatitis B surface antigen (HBsAg), antibody to hepatitis B e antigen (anti-HBe) and antibody to hepatitis B core antigen (anti-HBc), while antibody to hepatitis B surface antigen (anti-HBs) and HBV DNA were negative. Later the patient received chemotherapy for malignancy. However, this was interrupted due to elevated liver enzymes. At the same time HBV DNA became positive. Lamivudine (LMV) therapy was administered immediately. However, the levels of serum aminotransferase and total bilirubin (TB) were still rising. Finally the patient died of fulminant hepatic failure. A sequence revealed HBV genotype C (HBsAg subtype adw) with immune escape mutations, F8L, S34L, F41S, G44V, F93C, V96G, L110I, C149Y and F161Y. The high morbidity and mortality of this complication is one of the major obstacles to completing the standard treatment for malignancy in HBV carriers. Therefore, the relative risk of antiviral prophylactic failure should be further assessed and the optimal strategy for antiviral prophylaxis in HBsAg-positive patients with oncologic and hematologic malignancies undergoing chemotherapy should be revised.

Review article: the reversibility of cirrhosis

BACKGROUND

Cirrhosis is the end result of many types of chronic liver diseases. Recent developments in the understanding of the process of hepatic fibrogenesis have revealed that the process is a dynamic one and a capacity for recovery from any degree of fibrosis including those associated with cirrhosis is plausible.

AIM

To review current evidence of histopathological reversibility following drug therapy of more common aetiologies of cirrhosis.

METHODS

A PubMed search was performed and the evidence for histopathological regression of advanced fibrosis/cirrhosis following drug therapy was reviewed as of the end of February 2012.

RESULTS

There is abundant clinical evidence in support of the idea of the reversibility of cirrhosis in patients with different aetiologies of advanced hepatic disease including viral, autoimmune and metabolic/infiltrative liver disease.

CONCLUSIONS

The concept of cirrhosis has changed from being a form of static and irreversible entity to a dynamic and reversible diseases stage. Novel therapeutic strategies are under investigation to target specific steps in the process of fibrogenesis with the aim of reversing advanced fibrosis/cirrhosis.

Clinical course of chronic hepatitis B patients who were off-treated after lamivudine treatment: analysis of 138 consecutive patients

BACKGROUND/AIMS

Little is known about the long-term outcome of chronic hepatitis B (CHB) patients who discontinued antiviral therapy. We intended to analyze the long-term outcome of CHB patients who discontinued lamivudine therapy and to evaluate predictors for post-treatment outcome.

MATERIAL/METHODS

From 2007 to 2008, 138 lamivudine off-treated CHB patients with alanine aminotransferase normalization were consecutively enrolled. Post-treatment virologic relapse, biochemical breakthrough, hepatitis flare, and retreatment results were retrospectively analyzed.

RESULTS

Among 138 patients, 102 were initially HBeAg-positive at the start of lamivudine treatment. Virologic relapse, biochemical breakthrough, and hepatitis flare were observed in 45.2, 52.9, and 12.7% of HBeAg-positive and 29.4, 30.6, and 8.3% of HBeAg-negative patients during the median follow-up of 28 and 30 months, respectively. The cumulative virologic relapse and biochemical breakthrough rates were significantly lower in patients with HBV DNA <50 copies/mL than 50-104 copies/mL at lamivudine cessation. Hepatitis flare was observed in 4.8 and 11.8% of HBeAg-positive and HBeAg-negative patients with HBV DNA <50copies/mL, respectively. Thirty-eight among 138 patients received retreatment and most of them achieved biochemical (37/38) and virologic response (35/38) within 1 year of retreatment. Undetectable serum HBV DNA (<50 copies/mL) and young age at lamivudine cessation were inversely associated with virologic relapse. Undetectable HBV DNA at cessation, female, and initial HBeAg-negative were inversely associated with biochemical breakthrough.

CONCLUSIONS

Post-treatment virologic relapse and biochemical breakthrough incidence were low in patients who achieved undetectable viral titer at lamivudine cessation. Retreatment after biochemical breakthrough or virologic relapse was safe and effective. Intermittent antiviral therapy might be cautiously considered in appropriately selected CHB patients.

Hepatitis B-positive donors in renal transplantation: increasing the deceased donor pool

It is reasonable to transplant HbsAg-positive kidneys into recipients who are themselves hepatitis B surface antigen (HbsAg) positive with appropriate antiviral treatment after transplantation. Although there are limited data regarding the hepatitis B virus (HBV) transmission risk following transplantation of kidneys from HbsAg-positive donors into HBV-immune recipients, current literature suggests that the risk of chronic infection in the recipient can be prevented by using antiviral agents or by boosting protective anti-HBs titers. The risk of chronic HBV infection following transplantation of kidneys from HbsAg-positive donors for HBV-naive recipients is high but can be minimized by administering lifelong antiviral therapy. Such a policy could be considered in an urgent situation. The most cost-effective antiviral prophylaxis strategy is lifelong lamivudine. Kidneys from HBsAg neg/anti-HBcore pos recipients are associated with a low rate of chronic HBV infection in the recipient and therefore can no longer be regarded as marginal donors. Booster vaccination to achieve protective HBV immunity or lifelong lamivudine therapy should prevent posttransplant HBV infection. Hence, we believe that strategies allowing transplantation of kidneys from donors with HBV can be undertaken safely with careful selection and matching of donors and recipients increasing access to kidney transplantation.

One year of Lamivudine therapy for portuguese patients with chronic hepatitis B

OBJECTIVE

To assess the efficacy of lamivudine treatment on hepatitis B e antigen (HBeAg) and/or hepatitis B surface antigen (HBsAg) seroconversion, on other virological and serological markers of response including hepatitis B virus (HBV) DNA and serum aminotransferases, and the safety of lamivudine treatment in hepatitis B patients.

PATIENTS

This phase III open-label study evaluated the virological and biochemical response to lamivudine in 70 Portuguese patients with HBeAg positive chronic hepatitis B. Patients were treated with lamivudine 100mg once daily for 12 months.

METHODS

Antiviral activity was assessed by measuring alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels at all protocol visits, and hepatitis B serology and HBV DNA were performed at baseline and at month 12 visits. Evaluation of safety and tolerance was based on clinical adverse events and laboratory analyses.

RESULTS

The primary endpoint was virological response at month 12, defined as loss of detectable HBeAg from serum with a reduction of HBV DNA to undetectable levels, and this was observed in 19/69 (27.5%) of patients. Almost half of the patients were HBV DNA negative by this time. Mean ALT values decreased steadily during treatment and by 12 months 61% of patients had values within the normal range. HBeAg seroconversion (HBeAg negative, HBeAb positive) was achieved in 27.9% of patients by 12 months, although all patients remained HBsAg positive.

CONCLUSION

Lamivudine was well tolerated and the incidence of adverse events was similar to those reported in previous studies. Lamivudine treatment resulted in virological and biochemical improvements in HBeAg positive chronic hepatitis B patients, with HBeAg seroconversion in one-third of patients.

Hepatitis B: Treatment to prevent perinatal transmission

Hepatitis B remains a significant health issue and a leading cause of cirrhosis and hepatocellular carcinoma worldwide. Transmission of the hepatitis B virus, despite the availability of the vaccine, still occurs, particularly in the perinatal setting. Studies have shown that mothers with active viremia especially those with very high viral levels (>10⁸ copies/mL or >10⁷ IU/mL) are at increased risk of hepatitis B virus transmission, even with appropriate immunoprophylaxis at birth. With the development of new and relatively safe oral antiviral therapies, assessment with the mother about the risks and benefits of antiviral therapy should be discussed in those with highest transmission risk.

Management of chronic hepatitis B in pregnancy

Pregnancy associated with chronic hepatitis B (CHB) is a common and important problem with unique challenges. Pregnant women infected with CHB are different from the general population, and their special problems need to be considered: such as the effect of hepatitis B virus (HBV) infection on the mother and fetus, the effect of pregnancy on replication of the HBV, whether mothers should take HBV antiviral therapy during pregnancy, the effect of these treatments on the mother and fetus, how to carry out immunization of neonates, whether it can induce hepatitis activity after delivery and other serious issues. At present, there are about 350 million individuals with HBV infection worldwide, of which 50% were infected during the perinatal or neonatal period, especially in HBV-endemic countries. Currently, the rate of HBV infection in the child-bearing age group is still at a high level, and the infection rate is as high as 8.16%. Effective prevention of mother-to-child transmission is an important means of reducing the global burden of chronic HBV infection. Even after adopting the combined immunization measures, there are still 5%-10% of babies born with HBV infection in hepatitis B e antigen positive pregnant women. As HBV perinatal transmission is the main cause of chronic HBV infection, we must consider how to prevent this transmission to reduce the burden of HBV infection. In this population of chronic HBV infected women of childbearing age, specific detection, intervention and follow-up measures are particularly worthy of attention and discussion.

Viral response at 6 months is associated with treatment outcome of adefovir add-on therapy for lamivudine-resistance

BACKGROUND AND AIM

  Adefovir add-on therapy is recommended for patients infected with lamivudine-resistant hepatitis B virus (HBV). We aimed to describe the long-term treatment outcome and predictors for good response of adefovir add-on therapy.

METHODS

A total of 559 chronic hepatitis B (CHB) patients who had been treated for at least 12 months with adefovir add-on therapy due to resistance to lamivudine were retrospectively included. Complete virologic response (CVR) was defined as serum HBV DNA <9IU/mL. Viral responses at 6months were classified as PCR negativity, partial virologic response (PVR, HBV DNA <2000 IU/mL), or inadequate virologic response (IVR, HBV DNA≥2000IU/mL).

RESULTS

The median duration of follow-up was 31.5 months (range, 12-56). The cumulative probabilities of CVR during adefovir add-on therapy were 58%, 70%, 78%, and 80% at 12, 24, 36, and 43 months, respectively. The cumulative rates of resistance to adefovir were 0.4%, 0.8%, and 3.1% at 12, 24, and 36 months, respectively. The only baseline factor associated with CVR (hazard ratio 0.83, 95% confidence interval 0.62-0.91, P≤0.001) and resistance to adefovir (hazard ratio 1.925, 95% confidence interval 1.13-3.30, P=0.017) was serum HBV DNA level. Comparison of the cumulative rates of CVR and resistance to adefovir according to viral response at 6months showed significant differences among the three groups (P<0.0001 and P= 0.0005, respectively).

CONCLUSIONS

Pre-treatment HBV DNA level and viral response at 6months is associated with treatment outcome for adefovir-add on therapy in lamivudine resistance.

Prevention and management of drug resistant hepatitis B virus infections

In the past decade, broadened therapeutic options of oral direct antiviral agents for the treatment of chronic hepatitis B infection include: Lamivudine, Adefovir Dipivoxil, Telbivudine, Entecavir and Tenofovir Disoproxil Fumarate. These direct oral antiviral agents effectively suppress the replication of the virus and reduce the risk of potential liver-related complications. However, prolonged use of these nucleos(t)ide analogues has been associated with drug resistance that compromises the initial clinical benefits. Moreover, the oncogenic risk of mutations due to prolonged nucleos(t)ide analogue therapy needs to be further investigated by in vitro and in vivo studies. In the current era of potent nucleotide analogues, new data are emerging, we are still facing the pool of patients who have developed resistance to the prior generation of nucleos(t)ide analogues. This paper aims to focus on incidence of antiviral drug resistance and virological breakthrough, prudent selection of initial therapy, on-treatment monitoring for drug resistance and revise treatment strategies for patients with resistant virus.

[Entecavir therapy for patients with hepatitis B virus-related decompensated cirrhosis]

BACKGROUND/AIMS

Entecavie (ETV) has a potent antiviral effect and low rates of resistance in hepatitis B virus (HBV) and is the first-line monotherapy in patients with HBV-related decompensated cirrhosis. We evaluated the efficacy of 12 months treatment with ETV and tried to determine predictive factors of response.

METHODS

Forty-five consecutive decompensated cirrhotic patients who received ETV (0.5 mg/day) for more than six months were included. All patients were positive for HBV DNA, and the Child-Turcotte-Pugh (CTP) scores were over 8 point. Seventeen patients were HBeAg-positive. CTP score, model for end-stage liver disease (MELD) score, serum markers of liver function and HBV DNA were assessed every 3 months.

RESULTS

ETV treatment for 12 months resulted in improvement of CTP and MELD scores. Pre-treatment mean CTP and MELD score were decreased from 10.1 (±2.0) and 13.48 (±4.05) to 7.24 (±2.0) and 9.68 (±4.85) at 12 months, respectively. The 1-year cumulative rates of HBV DNA negativity and HBeAg loss were 88.9% and 52.9%, respectively, by intention-to-treat analysis. Thirty-two (71.1%) showed improvement in CTP score. Eleven patients did not show change, and 2 patients got worse. The AST/ALT, albumin, bilrubin, prothrombin time were significantly normalized within six months. The good responder group had high level of prothrombin time than the poor responder group (p=0.004).

CONCLUSIONS

Our result shows that entecavir can improve liver function in about 70% of patients with HBV related decompensated liver cirrhosis. INR may be a predictive factor of good response with entecavir in these patients.

Cost-effectiveness of maternal treatment to prevent perinatal hepatitis B virus transmission

OBJECTIVE

To estimate the cost-effectiveness of maternal lamivudine or hepatitis B immune globulin (HBIG) treatment, in addition to standard neonatal immunoprophylaxis, for the prevention of perinatal hepatitis B virus transmission.

METHODS

A decision-tree model was created to estimate the cost-effectiveness of maternal administration of either lamivudine or HBIG in the third trimester to prevent perinatal hepatitis B transmission compared with no maternal treatment. The model was first estimated for each treatment using overall transmission rates, and then stratified by maternal hepatitis B virus DNA viral load.

RESULTS

The model estimated that for each 100 hepatitis B surface antigen positive pregnant women treated with lamivudine, 9.7 cases of chronic hepatitis B virus infections are prevented, with a cost-savings of $5,184 and 1.3 life-years gained per patient treated. For HBIG, 9.5 cases of chronic hepatitis B virus infections are prevented for each 100 pregnant women treated, with a cost-savings of $5,887 and 1.2 life-years gained per patient treated. Under baseline assumptions, lamivudine remains cost-saving unless the reduction in perinatal transmission is less than 18.5%, and HBIG remains cost-saving unless the reduction in perinatal transmission is less than 9.6%.

CONCLUSION

In this decision analysis, administration of lamivudine or HBIG to hepatitis B surface antigen positive pregnant women for the prevention of perinatal transmission of hepatitis B is cost-savings across a wide range of assumptions.

LEVEL OF EVIDENCE

III.

Detection of mixed populations of wild-type and YMDD hepatitis B variants by pyrosequencing in acutely and chronically infected patients

BACKGROUND

Lamivudine (LAM) is associated with the highest known rate of resistance mutations among nucleotide analogs used to treat chronic hepatitis B virus (HBV) infection. Despite this, LAM continues in widespread use, especially in combination therapies. The primary LAM resistance mutation (rtM204V/I) occurs in the YMDD motif of HBV polymerase. The aim of this study was to characterize Brazilian HBV isolates from acute and chronic cases by direct sequencing, and to identify HBV quasispecies in the YMDD motif using a pyrosequencing method capable of detecting single-nucleotide polymorphisms. HBV DNA from serum samples of 20 individuals with acute HBV infection and 44 with chronic infection undergoing antiviral therapies containing LAM were analyzed by direct sequencing and pyrosequencing methods.

RESULTS

Phylogenic analyses of direct-sequenced isolates showed the expected genotypes (A, D and F) for the Brazilian population in both acute and chronic infections. However, within genotype A isolates, subgenotype A2 was more frequently detected in acute cases than in chronic cases (P = 0.012). As expected, none of the individuals with acute hepatitis B had LAM-resistant isolates as a dominant virus population, whether detected by direct sequencing or pyrosequencing. However, pyrosequencing analyses showed that 45% of isolates (9/20) had minor subpopulations (4-17%) of LAM-resistant isolates. Among chronic patients undergoing LAM treatment, YMDD mutants were frequently found as a dominant virus population. In cases where wild-type virus was the dominant population, subpopulations of YMDD variants were usually found, demonstrating the complexity of HBV quasispecies.

CONCLUSIONS

YMDD variants were frequently detected as a minor population in acute HBV infection. The occurrence of pre-existing variants may lead to a high frequency of resistant mutants during antiviral therapy in the chronic phase. In chronic infection, detection of YMDD variants before virological or biochemical breakthrough might contribute to making better therapy choices and thus improving treatment outcome.

Pre-existing YMDD mutants in treatment-naïve patients with chronic hepatitis B are not selected during lamivudine therapy

Although the rate at which mutations in the tyrosine-methionine-aspartate-aspartate (YMDD) motif of hepatitis B virus polymerase form is high during prolonged lamivudine (LAM) therapy, these mutations sometimes occur naturally in treatment-naïve patients with chronic hepatitis B. The prevalence of natural YMDD mutants differs geographically, and its clinical significance during LAM therapy is unknown. This study aimed to investigate whether pre-existing YMDD mutants were selected during LAM therapy. It included 14 treatment-naïve patients who were treated with LAM for at least 9 months. LAM resistance was evaluated before and at 3-month intervals during treatment. Mutations were analyzed by direct sequencing, restriction fragment mass polymorphism (RFMP) assays, and a single-step multiplex polymerase chain reaction (PCR) test using dual-priming oligonucleotide (DPO) primers. DPO-based multiplex PCR showed two YMDD mutations in two patients before LAM therapy; rtM204V and rtL180M + rtM204V/I. Further, two patients had an rtL180M mutation without an accompanying rtM204V/I mutation. No mutant was detected in any patient by direct sequencing or the RFMP assay before LAM therapy. A virological response was observed at 3 months in all patients with pre-existing YMDD mutants. All mutations disappeared after 3 months of LAM therapy, and during the follow-up period, no re-emergence was detected by any of the three methods. Further, the viral load was suppressed optimally. In conclusion, pre-existing YMDD mutants were cleared early during the course of LAM therapy, which produced a consistent virological response, and the mutants were not selected by LAM therapy.

HBV DNA suppression and HBsAg clearance in HBeAg negative chronic hepatitis B patients on lamivudine therapy for over 5 years

BACKGROUND & AIMS

In long-term responder patients, it is unclear whether lamivudine (LAM) monotherapy should be continued or switched to a high-genetic-barrier analogue. This study aims at assessing LAM efficacy over a 5-year period and the residual risk of drug resistance. The rate of HBsAg clearance and LAM long-term safety profile were also evaluated.

METHODS

One hundred and ninety-one patients with chronic HBeAg-negative hepatitis B successfully treated with LAM monotherapy for at least 5 years were included. Biochemical and virological tests were assessed every 3 months in all patients and HBsAg quantification was performed in 45/191. Reverse-transcriptase (RT) region was directly sequenced in virological breakthrough patients.

RESULTS

One hundred and ninety-one patients (148 males, median age 53 years, 72 with compensated cirrhosis) responding to 60-month LAM monotherapy continued to receive LAM monotherapy beyond the initial 5 years and were followed for an additional 36-month median period (range 1-108). Virological response was maintained in 128/191 patients (67%) and HBsAg clearance was observed in 15/128 (11.7%) after a 32-month median period (range 1-65). The 63 remaining patients (33%) showed virological breakthrough after a 15-month median treatment (range 1-78). RT region analysis was performed in 38/63 breakthrough patients and LAM resistant mutations were found in 37/38. No significant side effects were observed.

CONCLUSIONS

In long-term responder patients, continuation of LAM monotherapy resulted in persistent viral suppression in most cases with undetectable HBV DNA by real-time PCR; moreover, 11.7% of these patients cleared HBsAg. Selection of LAM resistance, however, can still occur even after successful long-term therapy, thus emphasising the importance of a careful virological monitoring.

Renal tubular dysfunction during long-term adefovir or tenofovir therapy in chronic hepatitis B

BACKGROUND

Adefovir and tenofovir are nucleotide analogues used as long-term therapy of chronic hepatitis B. Side effects are few, but prolonged and high-dose therapy has been associated with proximal renal tubular dysfunction (RTD).

AIM

To assess the incidence of RTD during long-term nucleotide therapy of chronic hepatitis B.

METHODS

A total of 51 patients being treated at the Clinical Center, National Institutes of Health were studied. Diagnosis of RTD required de novo appearance of at least three of five features: hypophosphataemia, hypouricaemia, serum creatinine elevation, proteinuria or glucosuria.

RESULTS

Among 51 patients treated for 1-10 (mean 7.4) years with adefovir (n = 42), tenofovir (n = 4) or adefovir followed by tenofovir (n = 5), 7 (14%) developed RTD. Time to onset ranged from 22 to 94 (mean 49) months with an estimated 10-year cumulative rate of 15%. All seven had low urinary percent maximal tubular reabsorption of phosphate (<82%). Patients with RTD were older (58 vs. 44 years; P = 0.01) and had lower baseline glomerular filtration rates (82 vs. 97 cc/min; P = 0.08) compared to those without; but did not differ in other features. Six patients with RTD were switched to entecavir, all subsequently had improvements in serum phosphate (2.0-3.0 mg/dL), creatinine (1.6-1.1 mg/dL), uric acid (2.7-3.8 mg/dL) and proteinuria.

CONCLUSIONS

Renal tubular dysfunction develops in 15% of patients treated with adefovir or tenofovir for 2-9 years and is partially reversible with change to other antivirals. Monitoring for serum phosphate, creatinine and urinalysis is prudent during long-term adefovir and tenofovir therapy.

Emerging pipeline drugs for hepatitis B infection

INTRODUCTION

Chronic hepatitis B virus (HBV) infection continues to represent a global health concern with an estimated 350 - 400 million people infected worldwide. Current treatment options are either of two IFN-based therapies or either of five oral nucleos(t)ide analogs which are used as monotherapy or in combination. Control of viral replication can be achieved basically in all patients today. However, despite the clinical efficacy of antivirals, long-term management remains a clinical challenge mainly due to the slow kinetics of HBsAg clearance. Emergence of viral resistance has been a challenge in the past with some but not all oral therapies. The development of novel therapeutic agents with different mechanisms of action might provide new opportunities to clear HBsAg and achieve HBsAg seroconversion which could be maintained off therapy. The long-term efficacy of combinations of IFN and/or nucleos(t)ide analogs might achieve antiviral synergy, preventing drug resistance and clearing viral covalently close circular DNA and infected cells.

AREAS COVERED

This article provides a review of recent data on the safety and efficacy of existing and emerging agents for the treatment of chronic hepatitis B infection.

EXPERT OPINION

Currently, entecavir and tenofovir offer a safe and effective treatment option for patients with chronic HBV with minimal to no resistance. Although entecavir and tenofovir are able to suppress replication in essentially all patients, achieving HBsAg seroconversion remains suboptimal among all antiviral therapy. There are a number of new therapies in the pipeline for the treatment of chronic HBV infection as well as revisiting IFN combined or sequential to antiviral therapy.

Use of nucleoside (tide) analogues in patients with hepatitis B-related acute liver failure

BACKGROUND AND AIMS

The efficacy of nucleoside(tide) analogues (NA) in the treatment of acute liver failure due to hepatitis B virus (HBV-ALF) remains controversial. We determined retrospectively the impact of NAs in a large cohort of patients with HBV-ALF.

METHODS

The US Acute Liver Failure Study Group, a 23-site registry, prospectively enrolled 1,413 patients with ALF with different etiologies between 1998 and 2008. Of those, 105 patients were identified as HBV-ALF patients, of whom we excluded those without data on NA use or with co-infection with hepatitis C, leaving 85 patients, 43 of whom had received NA treatment. HBV-DNA on admission was quantified by real time polymerase chain reaction.

RESULTS

The treated and untreated groups were similar in most respects but differed significantly in regard to higher aminotransferase and bilirubin levels and hepatic coma grades, all being observed in the untreated group. Median duration of NA treatment was 6 days (range, 1-21 days). Overall survival in the NA treated and untreated groups were 61 and 64%, respectively (P = 0.72). Rates of transplant-free survival were 21 and 36% in the treated and untreated groups, respectively (P = 0.42). Multivariate analysis revealed that not using a NA [odds ratio (OR) 4.4, 95% CI 1.1-18.1, P = 0.041], hepatic coma grade I or II [OR 14.4, 95% CI 3.3-62.8, P < 0.001] and prothrombin time (PT) [OR 0.59, 95% CI 0.39-0.89, P = 0.012] were predictors of improved transplant-free survival.

CONCLUSIONS

Patients who are admitted with established HBV-ALF do not appear to benefit from viral suppression using nucleoside(tide) analogues presumably because of rapid disease evolution and short treatment duration. Despite the lack of benefit, NAs should still be given to transplantation candidates since viral suppression prevents recurrence after grafting.

Chronic hepatitis B infection

The management of chronic hepatitis B virus (HBV) infection requires understanding the natural history of the disease as well as the risks, benefits, and limitations of the therapeutic options. This article covers the principles governing when to start antiviral therapy, discusses recent advances using hepatitis B surface antigen quantification to better define various phases of infection, describes the use of HBV core, precore, and viral genotyping as well as host IL28B genotyping to predict response to interferon therapy, and reports on the management of HBV in 3 special populations (pregnancy, postliver transplantation, and in the setting of chemotherapy or immunosuppression).

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effectiveness of hepatitis B treatment in clinical practice

It is important to examine the effectiveness of current therapies for chronic hepatitis B in clinical practice, given the therapeutic advances over the past 15 years. A 2010 Institute of Medicine report on hepatitis and liver cancer stated that the public and health care providers have a lack of knowledge and awareness about viral hepatitis, and that there is a gap between medical innovation and community care. We review the efficacy of hepatitis B treatment, based on results from clinical trials, and discuss the effectiveness of these treatments in clinical practice. We also discuss why having efficacious treatments alone would have a small impact on the global health burden of hepatitis B, and highlight the importance of educating the public and the medical community and coordination of care.

Antiviral therapies: focus on hepatitis B reverse transcriptase

Hepatitis B virus (HBV) is the etiologic agent of mankind's most serious liver disease. While the availability of a vaccine has reduced the number of new HBV infections, the vaccine does not benefit the approximately 350 million people already chronically infected by the virus. Most of the drugs approved by the FDA for the treatment of hepatitis B target the reverse transcriptase (RT or P gene product) and are nucleoside RT inhibitors (NRTIs) that suppress viral replication. However, prolonged monotherapies directed against a single target result in the emergence of viral resistance. HBV genotypic differences affect NRTI resistance, and because the reading frames of the S (surface antigen) and P genes partially overlap, genomic differences that affect the surface of the virus may also alter the viral polymerase sequence, function and drug susceptibility. The scope of this review is to assess the effects of HBV genotypic variation on the development of drug resistance to NRTIs. Some RT residues that vary among different genotypes are in the vicinity of residues that mutate and give rise to NRTI resistance. Interactions between these amino acids can help explain the effect of HBV genotype on the development of NRTI resistance during antiviral therapies, and might help in the design of improved therapeutic strategies.

Hepatitis B-associated fibrosis and fibrosis/cirrhosis regression with nucleoside and nucleotide analogs

Hepatitis B virus (HBV) infection currently accounts for approximately 600,000 deaths per year resulting from progression of liver fibrosis to cirrhosis and hepatocellular carcinoma. Treatment of chronic hepatitis B with antiviral agents aims to improve survival through the reduction of HBV DNA to undetectable levels and the resultant prevention of disease progression. In recent years, observations in various disease areas have shown that liver fibrosis can be reversed if the underlying cause of the liver damage is effectively addressed. In line with these observations, there is now considerable evidence to suggest that effective sustained suppression of HBV replication with long-term anti-HBV treatment can result in measurable improvements in liver fibrosis over time, even in patients with advanced cirrhosis. This review article provides an overview of currently available data on regression of fibrosis and cirrhosis in patients with chronic hepatitis B treated with nucleoside and nucleotide analog inhibitors of HBV.

Assessment of HBV flare in a randomized clinical trial in HIV/HBV coinfected subjects initiating HBV-active antiretroviral therapy in Thailand

Abstract

Clinical Trial number

NCT00192595.

Hepatitis B surface antigen seroconversion is associated with favourable long-term clinical outcomes during lamivudine treatment in HBeAg-negative chronic hepatitis B patients

The aims of this study were to assess hepatitis B surface antigen (HBsAg) seroconversion and to determine its impact on the natural course of the disease in patients with HBeAg-negative chronic hepatitis B (CHB) during lamivudine (LMV) treatment. A total of 183 consecutive patients with HBeAg-negative CHB who were treated with LMV were included in the study. Data were retrospectively collected from outpatient visit charts. The primary endpoint was HBsAg seroconversion to anti-HBs. The secondary endpoint was to determine the development of cirrhosis. Loss of HBsAg was confirmed in 10 patients and seroconversion to anti-HBs in nine patients during LMV treatment or after its discontinuation. HBsAg seroconversion was achieved on-treatment in four patients after a median treatment duration of 30 months and off-treatment in the remaining five patients in a median 61 months after LMV discontinuation. The cumulative probability of HBsAg seroconversion increased from 0.6% at 1 year and 1.9% at 5 years to 21.5% at 10 years of LMV during and after LMV treatment. HBsAg clearance was preceded by undetectable serum hepatitis B virus (HBV) DNA. The majority of the patients responding to treatment had undetectable HBV DNA levels at 24 weeks of treatment. The cumulative probability of LMV resistance increased from 2.2% at 1 year to 37.3% at 5 years. No baseline parameter predicting either HBsAg seroconversion or the emergence of LMV resistance was identified. None of the patients with HBsAg seroconversion experienced virological breakthrough or disease progression during the follow-up period. These results indicate that HBsAg seroclearance can occur in patients with HBeAg-negative CHB under LMV therapy and predicts better clinical outcome.

The influence of YMDD mutation patterns on clinical outcomes in patients with adefovir add-on lamivudine combination treatment

BACKGROUND/AIM

The aim of this study was to assess the patterns of lamivudine (LAM)-resistant mutations and the influence on biochemical and virological responses to adefovir (ADV) add-on LAM combination therapy in patients with LAM-resistant chronic hepatitis B (CHB).

METHODS

Seventy-eight CHB patients with confirmed genotypic resistance to LAM, who initiated ADV add-on LAM combination treatment, were enrolled at our institution between April 2007 and April 2009.

RESULTS

The baseline tyrosine-methionine-aspartate-aspartate (YMDD) mutation patterns were as follows: rtM204I 45 (57.7%); and rtM204V + rtM204I/V 33 (42.3%). The decrease in the mean ± standard deviation (SD) serum log(10) HBV-DNA level did not differ between the patients carrying the rtM204I vs. rtM204IV +rtM204I/V mutations at 3, 6 and 12 months after the initiation of ADV add-on LAM combination treatment. The proportion of patients who achieved ALT normalization (<40 IU/L) 12 months after the initiation of ADV add-on LAM combination treatment were significantly higher in patients with a rtM204I mutation than rtM204V+ rtM204I/V mutations (39 [86.7%] vs. 22 [66.7%], P = 0.05). The proportion of patients in whom the log(10) HBV-DNA decreased <2 log(10) copies/ml, 6 months after the initiation of ADV add-on LAM combination treatment (non-responders), was significantly higher in patients with a rtM204V + rtM204I/V mutations than rtM204I mutation (7 [21.2%] vs. 2 [4.4%], P = 0.032).

CONCLUSION

Biochemical response at 12 months from baseline was better in patients with a rtM204I mutation than rtM204V+ rtM204I/V mutations. In addition, early treatment failure was more common in patients with rtM204V+ rtM204I/V mutations than a rtM204I mutation.

Long-term outcome of primary non-responders to tenofovir therapy in HIV/HBV-co-infected patients: impact of HBV genotype G

AIM

To evaluate the early virological response (EVR) to combined tenofovir-lamivudine or emtricitabine regimen in HBV/HIV-co-infected patients and the long-term efficacy of tenofovir.

METHODS

In this retrospective monocentric study, among the 166 HIV/HBV-co-infected patients regularly followed from 2003 to 2008 at Bichat Claude Bernard Hospital, 61 patients had received, either de novo combination therapy with tenofovir and lamivudine or emtricitabine (group I, n = 15) or add-on tenofovir to lamivudine therapy (group II, n = 46). The HBV polymerase region was sequenced and analysed for all patients with available samples.

RESULTS

All 15 group I patients achieved EVR vs 32 (82%) of group II patients (P = 0.15). Seven adherent group II patients met criteria for primary non-response, but achieved delayed response (DR) to therapy. In these seven patients, when compared with the 39 group II patients, there was a trend to longer duration of lamivudine pre-treatment and to higher rate of lamivudine-resistant mutants; and HBV genotype-G proportion was higher (P = 0.026). No virological breakthrough occurred after a median of 46 months follow up.

CONCLUSION

In these HBV/HIV-co-infected patients, first-line HBV therapy with tenofovir and emtricitabine or lamivudine was associated with EVR. However, DR to tenofovir was observed in 15% of patients who added tenofovir to lamivudine therapy, of whom four of seven (57%) had genotype G-HBV infection. No resistance was evidenced after 46 months of therapy even in patients with DR to tenofovir. At last, a good renal safety profile of TDF was observed after a median follow-up of 4 years of therapy.

Efficacy of lamivudine or entecavir on acute exacerbation of chronic hepatitis B

BACKGROUND/AIMS

Spontaneous acute exacerbation of chronic hepatitis B virus (HBV) infection occasionally occurs in its natural history, sometimes leading rapidly to fatal hepatic failure. We compared the effects of lamivudine (LAM) with those of entecavir (ETV) treatments in acute exacerbation of chronic hepatitis B with 500 IU/L or higher alanine aminotransferase (ALT) levels.

METHODS

Thirty-four patients with acute exacerbation were consecutively treated with LAM /ETV. Their clinical improvements were compared.

RESULTS

Among LAM-treated and ETV-treated patients, none showed a reduction of <1 log IU/mL in HBV DNA after 1 or 3 months of treatment. Initial virological response, defined as a reduction of 4 log IU/mL in HBV DNA at 6 months, with LAM and ETV, respectively, was 83.3% and 100%. One LAM patient developed hepatic encephalopathy, but all patients in both groups survived. Twelve months after treatment, 41.6% of 24 LAM group patients switched to another drug or added adefovir to their treatment due to the emergence of LAM-resistant mutants. On the other hand, patients receiving ETV did not need to change drugs.

CONCLUSIONS

ETV appears to be as effective as LAM in the treatment of patients with acute exacerbation of chronic hepatitis B. Clinicians should carefully start to treat these patients as soon as possible.

Comparison of entecavir and lamivudine in preventing hepatitis B reactivation in lymphoma patients during chemotherapy

During chemotherapy for lymphoma, the administration of cytotoxic agents and rituximab often results in hepatitis B reactivation (incidence, 14-72%). This study was designed to compare the efficacy of entecavir and lamivudine in preventing hepatitis B reactivation in lymphoma patients. Between January 2007 and February 2009, patients treated in four hospitals in China were screened to identify those most appropriate for analysis. These patients received either entecavir or lamivudine during chemotherapy and for 6 months after completion of chemotherapy. A total of 34 patients received entecavir and 89 patients received lamivudine. Compared with the lamivudine group, the entecavir group had significantly lower rates of hepatitis (5.9 vs 27.0%, P = 0.007), hepatitis B reactivation (0 vs 12.4%, P = 0.024) and disruption of chemotherapy (5.9 vs 20.2%, P = 0.042). All patients with hepatitis B reactivation had B-cell non-Hodgkin's lymphoma (stage III-IV). In lymphoma patients under chemotherapy treatment, entecavir is more effective than lamivudine in preventing hepatitis B reactivation. For patients with advanced stage disease, entecavir should be considered the primary preventive therapy.

Longitudinal assessment of liver stiffness by transient elastography for chronic hepatitis B patients treated with nucleoside analog

AIM

  To evaluate the association between liver stiffness measured by transient elastography (FibroScan) and the efficacy of long-term nucleoside analog (NA) treatment for patients with chronic hepatitis B.

METHODS

  Study 1: Forty-four chronic HBV patients had liver stiffness measured by FibroScan and underwent liver biopsy. Study 2: Group A: 22 patients started NA treatment at entry and FibroScan was done annually for 3 years. Group B: 23 patients started NA treatment prior to pretreatment FibroScan measurement, and FibroScan was done for from 3 to 5 years after the start of NA treatment.

RESULTS

  Study 1: The FibroScan values were significantly correlated with fibrosis stage (r = 0.672, P < 0.0001). Optimal cutoff of FibroScan values were 6.1 kPa for ≥ F1, 6.3 kPa for ≥ F2, 8.9 kPa for ≥ F3 and 12.0 kPa for F4. Study 2: For Group A, the baseline median FibroScan value was 8.2 kPa. FibroScan values significantly decreased annually for 3 years after the start of NA treatment (6.4 kPa, 5.8 kPa and 5.3 kPa at years 1, 2 and 3, respectively). For Group B, the FibroScan values did not significantly improve over the 3 years after the start of NA treatment.

CONCLUSIONS

  Liver stiffness, measured by transient elastography, of chronic hepatitis B patients treated with NA showed a rapid decline in the first 3 years followed by a more steady transition for from 3 to 5 years irrespective of long term virological effect.

Current Antiviral Therapy of Chronic Hepatitis B: Efficacy and Safety

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

Cost-effectiveness analysis of prophylactic lamivudine use in preventing vertical transmission of hepatitis B virus infection

BACKGROUND

As neonates born to mothers with positive hepatitis B e antigen may not be completely protected by hepatitis B vaccination, prophylactic lamivudine use in mothers with high viraemia has been proposed. However, the overall effectiveness and the balance between cost and benefit for such a prophylactic strategy have rarely been addressed.

OBJECTIVE

Using a review of recent literature, we aimed to assess the cost effectiveness, from the Taiwanese societal perspective, of administering prophylactic lamivudine to mothers to reduce vertical transmission of hepatitis B virus and its long-term sequelae in neonates.

METHODS

A meta-analysis of three randomized controlled trials was conducted to evaluate the efficacy of lamivudine versus placebo. A Markov decision model was constructed in which in both treatment arms infants received active and passive immunoprophylaxis. An economic evaluation was performed to calculate costs, acute infections averted, and QALYs gained. Probabilistic sensitivity analyses were conducted and a cost-effectiveness acceptability curve drawn. All these analyses were from the societal perspective. Costs ($US) were valued in year 2008 prices.

RESULT

Supplemental lamivudine use gained an additional 0.0024 QALYs and averted 0.23 acute infections per birth compared with the routine active-passive immunization without lamivudine. The cost-effectiveness analysis suggested that the use of additional prophylactic lamivudine dominated the routine strategy. The acceptability curve suggested that the probability of being cost effective under the willingness-to-pay threshold of $US20,000 was 94%.

CONCLUSION

This analysis suggests that supplemental use of lamivudine in mothers with high hepatitis B viraemia is effective in reducing vertical transmission and may be cost effective, from a Taiwanese societal perspective, compared with the routine active-passive immunization without lamivudine.

Antiviral resistance mutations potentiate HBV surface antigen-induced transcription of hfgl2 prothrombinase gene

Antiviral resistance mutations in the hepatitis B virus (HBV) polymerase (pol) gene have been demonstrated to play an important role in the progression of liver disease and the development of hepatocellular carcinoma. The HBV pol gene overlaps the S gene encoding surface antigen (HBsAg). Previous studies from our laboratory have shown that HBV core protein (HBc) and X protein (HBx), but not HBV S protein (HBs), promote hfgl2 prothrombinase transcription. To investigate whether the nucleotide (nucleoside)-induced resistant mutations of HBs potentiate transcription of hfgl2 prothrombinase gene, we generated two mutant HB expression constructs harboring rtM204V/sI195M or rtM204I/sW196L mutations. Two mutant expression plasmids were co-transfected with hfgl2 promoter luciferase-reporter plasmids and β-galactosidase plasmid in CHO cells and HepG2 cells, respectively. Luciferase assay showed that the rtM204I/V mutant HBs could activate the transcription of hfgl2 promoter compared with the wild type HBs. Site-directed mutagenesis and further experiment (co-transfection) demonstrated that transcription factor Ets translocated to its cognate cis-element in the hfgl2 promoter. The results show that mutated HBs caused by antiviral drug resistance induce transcription of the hfgl2 gene dependent on the transcription factor Ets.

The treatment of chronic hepatitis B: Focus on adefovir-like antivirals

Several options for the treatment of hepatitis B have been licensed in the last years: interferon, pegylated interferon, lamivudine, adefovir, entecavir, and telbivudine. In addition tenofovir has been licensed in the EU and is expected to be licensed in the USA in 2008. The antivirals can be divided into “lamivudine-like” and “adefovir-like”, which clinically differ in their capacity to induce “YMDD” mutants, which are the hallmark of lamivudine resistance. The differing resistance profile makes them good combination partners, even in the absence of synergy in antiviral potency.

Review article: current antiviral therapy of chronic hepatitis B

BACKGROUND

The indications and endpoints for treatment of chronic hepatitis B continue to evolve. The aim of the therapy for chronic hepatitis B is to achieve a long-term continued suppression of the hepatitis B virus (HBV) DNA to prevent disease progression leading to the development of cirrhosis and hepatocellular carcinoma.

AIM

To summarise current literature on therapy of chronic hepatitis B, with a focus on indications for therapy, preferred treatment options, and management of resistance and partial responders.

METHODS

A systematic review of the literature, with a focus on international guidelines, was performed.

RESULTS

Seven drugs are licensed for the treatment of chronic hepatitis B in many countries. The selection of a drug with high potency and low rate of resistance is essential to achieve rapid and long-term viral suppression. The prevention of the sequelae of antiviral drug resistance and appropriate management of viral breakthrough are major goals of current management. The addition or change to an antiviral agent that is not cross-resistant is critical to restore suppression of viral replication for patients with breakthrough resistance. Patient adherence to medication is essential to achieve adequate HBV DNA suppression.

CONCLUSIONS

The current treatment strategy of chronic hepatitis B is now standard: initial selection of entecavir, tenofovir, or peginterferon alfa-2a. Future studies are required to determine if combination therapy using two oral agents or peginterferon with an oral agent with a high genetic barrier to resistance might be superior to standard current monotherapy.

High rate of complete viral suppression with combination therapy in patients with chronic hepatitis B and prior treatment failure

BACKGROUND

Combination therapy for chronic hepatitis B virus (HBV) infection is recommended for patients with antiviral resistance (AVR) or partial response (PR) to earlier antiviral therapy; however, data on outcomes are limited.

GOALS

To determine the rate of complete viral suppression (CVS) with combination therapy and to compare CVS among different indications and treatment regimens.

METHODS

A cohort of 109 consecutive patients with chronic hepatitis B from 3 liver clinics in Northern California was retrospectively studied. All patients started combination therapy between April 2004 and August 2009 for the following indications: AVR (n = 29), PR (n = 60), or others (n = 20). Combination treatments included lamivudine (LAM), adefovir (ADV), telbivudine (LdT), entecavir (ETV), tenofovir (TDF), and emtricitabine (FTC). CVS was defined as undetectable serum HBV DNA <100 IU/mL.

RESULTS

Among the patients, who were nearly all Asian (99%), 73% had ≥ 2 prior treatments and 82% had treatment failure (AVR or PR). Median treatment duration of combination therapy was 21 months (range, 6 to 50 mo). The majority (77%) achieved CVS after 6 months of various combination regimens: 80% for ETV+TDF, 76% for TDF+LAM or FTC or LdT, 75% for ETV+ADV, and 69% for ADV+LAM or LdT (P = 0.86). After 6 months of therapy, CVS was observed in a similar proportion of patients treated for PR and AVR (72% and 74%, respectively).

CONCLUSIONS

Although the majority of 109 treatment-experienced patients had prior treatment failure, high rates of CVS were rapidly achieved and did not significantly differ between indications of AVR and PR or between ETV-based and TDF-based regimens.

Antiviral drugs for viruses other than human immunodeficiency virus

Most viral diseases, with the exception of those caused by human immunodeficiency virus, are self-limited illnesses that do not require specific antiviral therapy. The currently available antiviral drugs target 3 main groups of viruses: herpes, hepatitis, and influenza viruses. With the exception of the antisense molecule fomivirsen, all antiherpes drugs inhibit viral replication by serving as competitive substrates for viral DNA polymerase. Drugs for the treatment of influenza inhibit the ion channel M(2) protein or the enzyme neuraminidase. Combination therapy with Interferon-α and ribavirin remains the backbone treatment for chronic hepatitis C; the addition of serine protease inhibitors improves the treatment outcome of patients infected with hepatitis C virus genotype 1. Chronic hepatitis B can be treated with interferon or a combination of nucleos(t)ide analogues. Notably, almost all the nucleos(t) ide analogues for the treatment of chronic hepatitis B possess anti-human immunodeficiency virus properties, and they inhibit replication of hepatitis B virus by serving as competitive substrates for its DNA polymerase. Some antiviral drugs possess multiple potential clinical applications, such as ribavirin for the treatment of chronic hepatitis C and respiratory syncytial virus and cidofovir for the treatment of cytomegalovirus and other DNA viruses. Drug resistance is an emerging threat to the clinical utility of antiviral drugs. The major mechanisms for drug resistance are mutations in the viral DNA polymerase gene or in genes that encode for the viral kinases required for the activation of certain drugs such as acyclovir and ganciclovir. Widespread antiviral resistance has limited the clinical utility of M(2) inhibitors for the prevention and treatment of influenza infections. This article provides an overview of clinically available antiviral drugs for the primary care physician, with a special focus on pharmacology, clinical uses, and adverse effects.

Nucleoside/nucleotide analogues in the treatment of chronic hepatitis B

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

Hepatitis B: modern end points of treatment and the specter of viral resistance

The goal of antiviral treatment of chronic hepatitis B is to prevent the complications of cirrhosis, hepatic decompensation, HCC, and death. Because these clinical outcomes may take a long period of time to develop, it is important to use intermediate or surrogate end points to evaluate the efficacy and response to antiviral treatment, and to determine whether treatment can be safely stopped, especially given concern for the development of antiviral resistance with NUC therapy. Although normalization of ALT and suppression of HBV DNA viral replication are associated with favorable outcomes, the durability of their response is low, and these end points are insufficient markers for stopping treatment. HBeAg seroconversion is currently used to discontinue NUC treatment in patients with HBeAg-positive chronic hepatitis B, whereas the stopping rule for HBeAg-negative disease relies on HBsAg loss. However, HBsAg loss occurs very infrequently and is not a practical end point for clinical use, although quantitative HBsAg levels may be useful in identifying patients who could achieve a sustained virologic response to treatment.

Current Nucleos(t)ide Analogue Therapy for Chronic Hepatitis B

Although the prevalence of chronic hepatitis B has decreased considerably in recent years due to widespread use of the hepatitis B virus (HBV) vaccine, its prevalence still remains high in adults, and this can place a significant burden on health care in areas with endemic HBV. Since the introduction of nucleos(t)ide analogues (NUCs), there has been marked improvement in the care of patients with chronic hepatitis B, resulting in increased survival. However, the emergence of drug resistance in patients treated with NUCs is a major concern. The number of multi-drug resistant patients is increasing, and many patients may not respond to the currently available drugs. In this review, we describe the current status of NUC therapy for antiviral-naïve and -resistant patients.

Randomised clinical trial: efficacy of peginterferon alfa-2a in HBeAg positive chronic hepatitis B patients with lamivudine resistance

BACKGROUND

Previous studies suggested that a finite course of peginterferon alfa-2a may offer an alternative rescue therapy for patients with lamivudine resistance. However, because of the limitation of study design and small sample size, it is difficult to make definitive conclusion.

AIM

To explore the role of peginterferon alfa-2a, in the rescue treatment of HBeAg-positive chronic hepatitis B patients with lamivudine resistance.

METHODS

In this randomised study, chronic hepatitis B patients with lamivudine resistance were treated with peginterferon alfa-2a for 48 weeks (n=155) or adefovir for 72 weeks (n=80). All enrolled patients were treated with lamivudine for the first 12weeks.

RESULTS

At 6 months posttreatment, 14.6% (18/123) of peginterferon alfa-2a-treated patients achieved HBeAg seroconversion, in contrast to 3.8% (3/80) of adefovir-treated patients after 72 weeks continuous therapy (P=0.01). For peginterferon alfa-2a-treated patients, the rate of HBeAg seroconversion at week 72 was significantly higher in patients who had HBsAg decline >0.5 Log(10) IU/mL from baseline at week 24, compared with patients with HBsAg decline ≤0.5 Log(10) IU/mL from baseline at week 24 (25.5% vs. 7.7%, P=0.01). After 72 weeks continuous adefovir treatment, 22.5% of patients achieved HBV DNA <80 IU/mL, compared with 10.6% in peginterferon alfa-2a-treated patients at 6months off-treatment (P=0.02).

CONCLUSIONS

Overall, the response to peginterferon alfa-2a among patients with lamivudine resistance was suboptimal. HBeAg seroconversion rate at week 72 by 48 weeks peginterferon alfa-2a treatment was higher than continuous adefovir therapy. Monitoring HBsAg levels can help to predict response to peginterferon alfa-2a.

Hepatitis B in childhood: An update for the paediatrician

Hepatitis B virus (HBV) infection may lead to acute or chronic hepatitis, cirrhosis and hepatocellular carcinoma. The incidence rate of paediatric hepatitis B is 0.2/100,000 to 1.8/100,000 in Canada. Hepatitis B virus infection is acquired largely through mother-to-infant (vertical) or community-based (horizontal) transmission in early childhood, whereas older children are susceptible to HBV infection through exposure to contaminated blood during intravenous drug use or through sexual transmission. Immigrants from endemic areas and some Native Canadian populations are also at a higher risk for HBV infection. Infection with HBV may manifest in three forms: acute self-limited hepatitis, chronic hepatitis or massive hepatic necrosis causing acute liver failure. The identification of HBV infection and the characterization of the disease relies on serological and virological tests. The course of chronic hepatitis B may be classified into three phases: an immunotolerant phase, an active phase and an inactive phase. Current treatment options include interferon-alpha and lamivudine for individuals with elevated serum alanine aminotransferase levels and markers of persistent viral replication. Children with chronic hepatitis B require regular monitoring and age-appropriate lifestyle counselling. Paediatricians are well-positioned to promote vaccination and encourage testing of those who are at risk for hepatitis B. With effective universal vaccination against hepatitis B, this infection could be essentially eliminated in Canada.