Adefovir dipivoxil for the treatment of hepatitis B e antigen-negative chronic hepatitis B

Study on the Efficacy and Safety of Adefovir Dipivoxil Treatment in Post–Liver Transplant Patients With Hepatitis B Virus Infection and Lamivudine-Resistant Hepatitis B Virus

Hepatitis B virus (HBV) recurrence and de novo HBV infection are frequent events in liver transplantation recipients. Treatment with lamivudine is initially efficient in both infections but the incidence of lamivudine-resistant HBV emergence increases over time. Adefovir appears to be promising in post-liver transplantation patients with recurrent HBV infection and lamivudine-resistant HBV. This study analyzed adefovir treatment in 42 post-liver transplantation patients who developed recurrent HBV or de novo HBV infection with lamivudine-resistant HBV (54.8% HCV-coinfected). Patients received 10 mg of oral adefovir once daily for a mean period of time of 21.5 months (range from 12 to 31 months). In 62.9% of patients, ALT levels decreased significantly. Serum HBV-DNA was undetectable in 64% of the cases. Twenty percent of patients lost HBeAg marker and 13.3% of them developed anti-HBe. In 9.5% of recipients, HBsAg became negative. There was no significant change in serum creatinine levels. In only one patient was worsening of the renal function detected, making dose adjustment necessary. No other side effects were reported. Our results confirm the efficacy and safety of adefovir treatment in post-liver transplantation patients with lamivudine-resistant HBV, neither were adefovir-resistant mutations identified in patients after 21 months of therapy, nor were there adverse events, especially renal toxicity.

Acyclic nucleoside phosphonates: a key class of antiviral drugs

Almost 20 years after the broad antiviral activity spectrum of the first acyclic nucleoside phosphonates was described, several of these compounds have become important therapies for DNA virus and retrovirus infections. Here, we review the discovery and development of acyclic nucleoside phosphonates, focusing on cidofovir and its potential in the treatment of various herpes-, papilloma-, polyoma-, adeno- and pox-virus infections, adefovir for the treatment of hepatitis B and tenofovir for the treatment of AIDS and the prevention of HIV infections.

Current treatment and future directions in the management of chronic hepatitis B viral infection

The World Health Organization places hepatitis B virus (HBV) in the top 10 causes of death worldwide. It is estimated that there are over 400 million carriers of HBV as well. At least 20% to 30% of hepatitis B surface antigen (HBsAg) carriers will die of complications of chronic liver disease, including cirrhosis and liver cancer. The serious consequences of end-stage liver disease and liver cancer occur in 30% of chronic carriers and confront patients and physicians throughout the world. Vaccination is the major form of treatment (prevention) that may eventually eliminate HBV worldwide. This article discusses the currently available treatments as well as evolving treatments for chronic HBV infection.

A review of entecavir in the treatment of chronic hepatitis B infection

BACKGROUND

Infection with the hepatitis B virus (HBV) affects two billion people worldwide, and an estimated 400 million people are chronically infected. Currently, FDA-approved regimens for the treatment of chronic HBV include interferon-alpha2b, peginterferon-alpha2a, lamivudine, adefovir dipivoxil, and recently, entecavir.

OBJECTIVE

The purpose of this review is to evaluate the pharmacokinetic and pharmacodynamic properties, and the clinical efficacy and safety of entecavir in the treatment of nucleoside-naĩve and nucleoside-resistant HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB). SEARCH METHODOLOGY: Computerized searches of PubMed and International Pharmaceutical Abstracts from 1985 to July 10, 2005, were performed with the search headings: entecavir, BMS-200475, and chronic hepatitis B.

FINDINGS

Entecavir, a new deoxyguanosine analog, represents a third agent within the nucleoside/nucleotide HBV polymerase inhibitor class with distinct advantages over lamivudine and adefovir dipivoxil: it has a three-step mechanism of action, is the most potent inhibitor of HBV DNA polymerase, is not associated with any major adverse effects, and has a limited potential for resistance. In phase II and III clinical trials, entecavir was found to be superior to lamivudine for all primary endpoints evaluated in both nucleoside-naïve and lamivudine-resistant patients. Entecavir was effective in both HBeAg-positive and HBeAg-negative nucleoside-naïve patients. At this time, optimal duration of entecavir therapy is unknown.

CONCLUSION

Entecavir represents a new first- or second-line treatment option for patients chronically infected with HBV. Long-term efficacy and safety studies as well as studies of entecavir in combination with interferon products or other nucleoside/nucleotide analogs are eagerly awaited.

The use of unequal randomisation ratios in clinical trials: a review

OBJECTIVE

To examine reasons given for the use of unequal randomisation in randomised controlled trials (RCTs).

MAIN MEASURES

Setting of the trial; intervention being tested; randomisation ratio; sample size calculation; reason given for randomisation.

METHODS

Review of trials using unequal randomisation. DATABASES AND SOURCES: Cochrane library, Medline, Pub Med and Science Citation Index.

RESULTS

A total of 65 trials were identified; 56 were two-armed trials and nine trials had more than two arms. Of the two-arm trials, 50 trials recruited patients in favour of the experimental group. Various reasons for the use of unequal randomisation were given. Six studies stated that they used unequal randomisation to reduce the cost of the trial, with one screening trial limited by the availability of the intervention. Other reasons for using unequal allocation were: avoiding loss of power from drop-out or cross-over, ethics and the gaining of additional information on the treatment. Thirty seven trials papers (57%) did not state why they had used unequal randomisation and only 14 trials (22%) appeared to have taken the unequal randomisation into account in their sample size calculation.

CONCLUSION

Although unequal randomisation offers a number of advantages to trials the method is rarely used and is especially under-utilised to reduce trial costs. Unequal randomisation should be considered more in trial design especially where there are large differences between treatment costs.

Successful treatment with tenofovir in a child C cirrhotic patient with lamivudine-resistant hepatitis B virus awaiting liver transplantation. Post-transplant results

Antiviral treatment can be complex in decompensated hepatitis B virus (HBV) cirrhosis because of potential emergence of lamivudine-resistant mutants and worsening liver function, and to multifactorial nephrotoxicity. Negative HBV-DNA status by hybridization before liver transplantation is a favorable prognostic factor. We present the case of a 54-year-old HBV+ liver transplantation candidate who, after testing negative for HBV-DNA, developed YMDD lamivudine-resistant mutants resulting in a deteriorated clinical condition. After 8 months of adefovir plus lamivudine double therapy, only partial response was achieved. Tenofovir was added to this regimen, and an early decline of HBV-DNA was seen at 4 weeks without adverse events. The patient underwent transplantation. At 21-month postoperative follow-up, the patient's outcome was excellent. Post-transplantation HBV prophylaxis, taking into account the prior development of mutants, consists of hepatitis B immunoglobulin plus lamivudine and adefovir. Tenofovir was well tolerated and produced a fast antiviral response, suggesting its potential value in combined antiviral treatment for liver transplantation candidates.

Hepatitis B in children: complexities in management

Chronic hepatitis B virus (HBV) infection by definition is persistence of hepatitis B surface antigen (HBsAg) in the serum for > or =6 months. The risk of developing chronic HBV infection ranges from 90% in neonates to <5% in immunocompetent adults. HBV acquired by perinatal infection has a prolonged immune-tolerant phase, characterized by the presence of hepatitis Be antigen (HBeAg), high HBV-DNA and normal alanine aminotransferase (ALT) levels. Efficient and multi-specific helper and cytotoxic T-cell response is essential for controlling HBV infection. Chronic HBV infection is characterized by a state of HBV-specific T-cell hyporesponsiveness. The goal of therapy in chronic HBV infection is to eliminate or significantly suppress HBV replication and prevent the progression of liver disease to cirrhosis with the potential development of liver failure or hepatocellular carcinoma (HCC). In adults, drugs currently licensed for treatment of HBV infection: are interferon-alpha (IFN-alpha), lamivudine (LMV) and adefovir dipivoxil (ADV), the first two are also licensed to use in children. IFN-alpha has the advantage of having a more durable response, fixed duration of treatment and lack of resistant mutants. The disadvantages of IFN-alpha include need for thrice-weekly injections, higher cost and more side-effects compared with the nucleoside analogues. Nucleoside analogues can be given orally and used in decompensated cirrhosis and transplant recipients. ADV and newer drugs like tenefovir can successfully treat mutants produced after prolonged LMV therapy. Current protocols exclude children with immunotolerant HBV. Periodic screening with liver ultrasound scan and alpha-fetoprotein (AFP) in all children with chronic HBV infection is recommended. The severe shortage of cadaveric donor organs has led to the use of marginal (including anti-HBc-positive) cadaveric donor livers in selected transplant candidates with high medical urgency; 5-10% of all liver transplants are because of HBV. Using hepatitis B immunoglobulin and nucleoside analogues has made the outcome following liver transplantation for hepatitis B, comparable with, if not slightly better, than that in patients with other diagnoses. Future treatments should be based on the restoration of HBV-specific T-cell responses to levels similar to that seen in subjects controlling HBV.

Synthesis of acyclic nucleoside phosphonates

Acyclic nucleoside phosphonates (ANPs) are important biologically active nucleotide analogs. They contain an isopolar phosphonomethyl function linked to the hydroxyl group of an acyclic side-chain via an undegradable ether group. Though their most important activity is antiviral, some exhibit cytostatic or antiprotozoic effects. The three most important groups of ANP are presented here as synthetic procedures for a large laboratory scale. Synthesis follows three principles: (1) introduction of a protected phosphonomethyl group to the hydroxyl on an appropriate alkyl side-chain of an acyclic nucleoside, (2) alkylation of the heterocyclic base by a synthon with all characteristic features of the future phoshonate-bearing side-chain, or (3) transformation of a reactive group at the heterocyclic base. The last step in all these cases is removal of the phosphonate esters. Preparation methods are described in detail for PMEA, PMEG, PMEDAP and its N(6)-cyclopropyl derivative, (R)-PMPA, and (S)-HPMPA, as well as all intermediates and synthons.

Adefovir dipivoxil alone or in combination with ongoing lamivudine in patients with decompensated liver disease and lamivudine-resistant hepatitis B virus

The purpose of this prospective study was to evaluate the efficacy and safety of adefovir dipivoxil with or without ongoing lamivudine in decompensated lamivudine-resistant chronic hepatitis B patients. Forty-six hepatitis B e antigen (HBeAg)-positive patients with decompensated liver function and lamivudine-resistant hepatitis B virus (HBV) were assigned to adefovir dipivoxil monotherapy (n=18) or combination therapy with ongoing lamivudine (n=28) according to their own preference. After 24 weeks of treatment, 83% of monotherapy and 86% of combination therapy showed serum HBV DNA below detection limit (<0.5 pg/mL). Alanine aminotransferase (ALT) normalized in 78% and 82% respectively. Median Child-Pugh-Turcotte (CPT) score or Model for End-Stage Liver Disease (MELD) score reduced significantly by 3 or 5 point in monotherapy and 2 or 2 point in combination therapy respectively. There were no significant differences in rate of undetectable serum HBV DNA, median change of ALT and median reduction of CPT or MELD scores between the two groups. In conclusion, both adefovir dipivoxil monotherapy and combination therapy with ongoing lamivudine result in comparable virologic, biochemical, and clinical improvements in HBeAg-positive patients with decompensated liver function and lamivudine-resistant HBV. Combination with lamivudine showed no additional benefit over monotherapy during 24 weeks of treatment in these patients.

A dose-ranging study of the efficacy and tolerability of entecavir in Lamivudine-refractory chronic hepatitis B patients

BACKGROUND & AIMS

Entecavir is a nucleoside analogue with potent in vitro activity against lamivudine-resistant hepatitis B virus (HBV). This randomized, dose-ranging, phase 2 study compared the efficacy and safety of entecavir with lamivudine in lamivudine-refractory patients.

METHODS

Hepatitis B e antigen (HBeAg)-positive and -negative patients (n = 182), viremic despite lamivudine treatment for > or =24 weeks or having documented lamivudine resistance substitutions, were switched directly to entecavir (1.0, 0.5, or 0.1 mg daily) or continued on lamivudine (100 mg daily) for up to 76 weeks.

RESULTS

At week 24, significantly more patients receiving entecavir 1.0 mg (79%) or 0.5 mg (51%) had undetectable HBV DNA levels by branched chain DNA assay compared with lamivudine (13%; P < .0001). Entecavir 1.0 mg was superior to entecavir 0.5 mg for this end point (P < .01). After 48 weeks, mean reductions in HBV DNA levels were 5.06, 4.46, and 2.85 log(10) copies/mL on entecavir 1.0, 0.5, and 0.1 mg, respectively, significantly higher than 1.37 log(10) copies/mL on lamivudine. Significantly higher proportions of patients achieved normalization of alanine aminotransferase levels on entecavir 1.0, 0.5, and 0.1 mg (68%, 59%, and 47%, respectively) than on lamivudine (6%). One virologic rebound due to resistance occurred (in the 0.5-mg group).

CONCLUSIONS

In HBeAg-positive and HBeAg-negative lamivudine-refractory patients, treatment with entecavir 1.0 and 0.5 mg daily was well tolerated and resulted in significant reductions in HBV DNA levels and normalization of alanine aminotransferase levels. One milligram of entecavir was more effective than 0.5 mg in this population.

Antiviral effect of oral administration of tenofovir disoproxil fumarate in woodchucks with chronic woodchuck hepatitis virus infection

Tenofovir disoproxil fumarate (TDF) is a nucleotide analogue approved for treatment of human immunodeficiency virus (HIV) infection. TDF also has been shown in vitro to inhibit replication of wild-type hepatitis B virus (HBV) and lamivudine-resistant HBV mutants and to inhibit lamivudine-resistant HBV in patients and HBV in patients coinfected with the HIV. Data on the in vivo efficacy of TDF against wild-type virus in non-HIV-coinfected or lamivudine-naïve chronic HBV-infected patients are lacking in the published literature. The antiviral effect of oral administration of TDF against chronic woodchuck hepatitis virus (WHV) infection, an established and predictive animal model for antiviral therapy, was evaluated in a placebo-controlled, dose-ranging study (doses, 0.5 to 15.0 mg/kg of body weight/day). Four weeks of once-daily treatment with TDF doses of 0.5, 1.5, or 5.0 mg/kg/day reduced serum WHV viremia significantly (0.2 to 1.5 log reduction from pretreatment level). No effects on the levels of anti-WHV core and anti-WHV surface antibodies in serum or on the concentrations of WHV RNA or WHV antigens in the liver of treated woodchucks were observed. Individual TDF-treated woodchucks demonstrated transient declines in WHV surface antigen serum antigenemia and, characteristically, these woodchucks also had transient declines in serum WHV viremia, intrahepatic WHV replication, and hepatic expression of WHV antigens. No evidence of toxicity was observed in any of the TDF-treated woodchucks. Following drug withdrawal there was prompt recrudescence of WHV viremia to pretreatment levels. It was concluded that oral administration of TDF for 4 weeks was safe and effective in the woodchuck model of chronic HBV infection.

Viral kinetics in patients with lamivudine-resistant hepatitis B during adefovir-lamivudine combination therapy

BACKGROUND/AIMS

Mathematical analysis of viral kinetics during lamivudine-adefovir combination therapy has not yet been performed in patients with lamivudine-resistant hepatitis B.

METHODS

In 8 patients with lamivudine-resistant hepatitis B, adefovir dipivoxil (10 mg/day) was added to ongoing lamivudine. Viral decay during the first 8 weeks of combination therapy was described by a biphasic model to determine the efficacy: epsilon, of blocking viral production, the clearance: c, of free virus, and the loss of infected cells: delta.

RESULTS

Median epsilon was 98%, median c was 0.7/day, and median delta was 0.07/day. No significant association was found between viral kinetic and baseline parameters and virologic and biochemical treatment response. When compared with viral kinetic constants reported for higher dose adefovir dipivoxil monotherapy, epsilon was lower (P=0.026) and delta was higher (P=0.008) in this study whereas c did not differ between both studies.

CONCLUSIONS

Although a recent study did not show any differences in the reduction of HBV DNA comparing monotherapy with adefovir dipivoxil to adefovir-lamivudine combination therapy in patients with lamivudine-resistant chronic hepatitis B, mathematical analysis of early viral kinetics suggests an additional effect of lamivudine on the infected cell loss during adefovir-lamivudine combination therapy.

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Safety and antiviral activity of emtricitabine (FTC) for the treatment of chronic hepatitis B infection: a two-year study

BACKGROUND/AIMS

The aim of this study was to evaluate long term safety and antiviral activity of different doses of emtricitabine given once daily to patients chronically infected with hepatitis B.

METHODS

Eligible patients were randomized in a double-blind, parallel study to evaluate 25, 100 or 200 mg once daily doses of emtricitabine for 48 weeks. Patients were then followed for an additional 48 weeks on open-label 200 mg emtricitabine. Serum HBV DNA, ALT, and hepatitis B serology were measured at regular intervals over the 2 years. Resistance surveillance was performed after 1 and 2 years on viremic samples, i.e. > 4700 copies/mL.

RESULTS

Emtricitabine was well tolerated and produced a dose proportional antiviral response. After 2 years, 53% of the patients had serum HBV DNA < or = 4700 copies/mL, 33% seroconverted to anti-HBe and 85% had normal ALT. Eighteen percent of the patients who had received 200 mg emtricitabine for 2 years developed resistance mutations.

CONCLUSIONS

Emtricitabine was well tolerated and demonstrated a potent antiviral response for up to 2 years in patients with chronic hepatitis B infection. Based on these data, 200 mg emtricitabine once daily was chosen as the optimal dose for future hepatitis B studies.

Treatment of chronic hepatitis B

In the last years, marked progress has been made in the treatment of chronic hepatitis B. The efficacy of lamivudine, the first nucleoside analogue available, is limited by the high incidence of resistance. Adefovir, which was recently approved has a comparable efficacy with a very low frequency of resistance. However, adefovir needs to be indefinitely administered as withdrawal of therapy is generally associated with reactivation and sustained response is uncommon. Recent large randomized controlled trials showed that PEG IFNs induce relatively high sustained response rates both in HBeAg positive and HBeAg negative chronic hepatitis B. So far, the combination of PEG IFN with lamivudine, used simultaneously, is disappointing in terms of short-term efficacy. However, long-term efficacy needs to be assessed and different schedules of combination (for example sequential) need to be evaluated. A number of nucleoside analogues, with favourable toxicity profiles and a promise of increased effectiveness against HBV, are at various stages of clinical development. Results of phase III trials of entecavir and emtricitabine confirmed their efficacy. However, while entecavir is associated with a low incidences of resistance, emtricitabine is associated with a relatively high incidence of resistance which limits its use as a monotherapy. The efficacy and safety of new and more potent drugs like telbivudine and clevudine need to be confirmed. The future of chronic hepatitis B therapy seems to be in the combination of different drugs. Ideally, the optimal drugs to combine would meet the following criteria: they should have different sites of action on HBV DNA replication, a potent antiviral effect, an excellent safety profile and they should induce a sustained response with a limited duration of therapy. Indeed, the concept of combination therapy has been recently developed in order to increase efficacy and to decrease the occurrence of viral resistance. However, so far few combinations have been evaluated. No combination therapy demonstrated a benefit as compared with monotherapy. More potent drugs and new combinations together with the understanding of the mechanisms of resistance to therapy are important challenges to improve the efficacy of treatment and decrease in the future the global burden related to chronic hepatitis B.

Liver transplantation for chronic hepatitis B with lamivudine-resistant YMDD mutant using add-on adefovir dipivoxil plus lamivudine

Lamivudine treatment in patients with chronic hepatitis B virus (HBV) infection may improve clinical state and suppress viral replication before liver transplantation. Emergence of lamivudine-resistant YMDD mutant is common. We report the results of liver transplantation in 16 patients with pretransplantation YMDD mutants after receiving lamivudine treatment for a median of 738 days (range, 400-1799 days). Adefovir dipivoxil (10 mg daily) was added on to lamivudine for a median of 20 days (range, 8-271 days) before (n = 11) or at (n = 5) liver transplantation, and the combination was continued indefinitely thereafter. Eight patients received additional intravenous hepatitis B immune globulin (HBIG) for a median of 24 months. Fifteen patients with known pre-adefovir HBV DNA levels had a median titer of 14,200 x 10(3) copies/mL (2 x 10(3) to 4,690,000 x 10(3) copies/mL), and 14 had HBV DNA >10(5) copies/mL. All but 1 patient remained positive for HBV DNA (by quantitative polymerase chain reaction [qPCR]) at the time of liver transplantation, and the titer was greater than10(5) copies/mL in 8 patients. The median follow-up after liver transplantation was 21.1 (range, 4.4-68.9) months. One patient (6%) died of an unrelated cause 12.2 months after transplantation, and 15 patients (94%) were alive with the original graft. All patients cleared HBV DNA and had no detectable HBV DNA by qPCR at the latest follow-up. Fourteen patients had cleared hepatitis B surface antigen (HBsAg), but 2 patients who received only adefovir dipivoxil and lamivudine without HBIG remained HBsAg positive after 7.7 and 9.5 months. Serum HBV DNA, however, was negative, and there was no biochemical or histological evidence of recurrence. Adefovir dipivoxil was well tolerated with no significant renal toxicity. In conclusion, a combination of add-on adefovir dipivoxil plus lamivudine therapy provides effective prophylaxis in patients with pretransplantation YMDD mutant that may be actively replicating. The cost effectiveness of additional passive immunoprophylaxis remains to be defined.

SEN virus seroprevalence in HIV positive patients: association with immunosuppression and HIV-replication

BACKGROUND

Patients infected with HIV are often co-infected with other viruses. SEN virus (SENV) was isolated from a HIV positive patient with intravenous drug use and post-transfusion hepatitis. SENV strains D and H seem to be relevant for the development of post-transfusion hepatitis. We compared the prevalence of SENV strains D and H and the viral load of SENV H in HIV-infected patients with healthy blood donors. The results were correlated with clinical markers such as HIV stage, CD4 cell count, HIV-RNA positivity, HAART or the transmission mode in HIV infected individuals.

OBJECTIVES

Blood samples of 143 HIV-positive patients were analysed and compared with a control group of 122 healthy blood donors. SENV D and -H was detected by PCR.

RESULTS

SENV was detectable in 15.4% (22/143) of HIV-positive patients compared to 10.4% (12/122) in the control group (P=0.18). SENV H DNA-levels were significantly higher in HIV-positive patients (P=0.01). The prevalence in patients with CD4 cells less than 200/mm(3) was 31% (13/42), compared to 12.3% (8/65) in cases with CD4 cells between 200 and 500/mm(3), and 2.8% in cases with CD4 cells above 500/mm(3) (P=0.002 for CD4 cells <200 versus CD4 cells >200, P=0.031 for CD4 cells <500 versus CD4 cells >500). Prevalence of these strains was not significantly influenced by CDC stages. SENV was detected significantly more frequent in patients with detectable HIV-RNA (P=0.005). Patients undergoing HAART were significantly less frequent positive for SENV D or -H (P=0.029) than patients without HAART. In a multivariate analysis using a logistic regression model HIV-RNA positivity and CD4 cell count were identified as independent factors for SENV prevalence.

CONCLUSION

SENV (D and H) prevalence is not significantly higher in HIV-positive patients in comparison to healthy blood donors. SENV prevalence depends on CD4 cell count and HIV-RNA.

Long-term therapy with adefovir dipivoxil for HBeAg-negative chronic hepatitis B

BACKGROUND

Treatment with adefovir dipivoxil for 48 weeks resulted in histologic, virologic, and biochemical improvement in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. We evaluated the effect of continued therapy as compared with cessation of therapy.

METHODS

One hundred eighty-five HBeAg-negative patients with chronic hepatitis B were assigned to receive 10 mg of adefovir dipivoxil or placebo once daily for 48 weeks (ratio, 2:1). After week 48, patients receiving adefovir dipivoxil were again randomly assigned either to receive an additional 48 weeks of the drug or to switch to placebo. Patients originally assigned to placebo were switched to adefovir dipivoxil. Patients treated with adefovir dipivoxil during weeks 49 through 96 were subsequently offered continued therapy. The primary end points were changes in hepatitis B virus (HBV) DNA and alanine aminotransferase levels.

RESULTS

Treatment with adefovir dipivoxil resulted in a median decrease in serum HBV DNA of 3.47 log copies per milliliter (on a base-10 scale) at 96 weeks and 3.63 log copies per milliliter at 144 weeks. HBV DNA levels were less than 1000 copies per milliliter in 71 percent of patients at week 96 and 79 percent at week 144. In the majority of patients who were switched from adefovir dipivoxil to placebo, the benefit of treatment was lost (median change in HBV DNA levels from baseline, -1.09 log copies per milliliter; only 8 percent of patients had levels below 1000 copies per milliliter at week 96). Side effects during weeks 49 through 144 were similar to those during the initial 48 weeks. Resistance mutations rtN236T and rtA181V were identified in 5.9 percent of patients after 144 weeks.

CONCLUSIONS

In patients with HBeAg-negative chronic hepatitis B, the benefits achieved from 48 weeks of adefovir dipivoxil were lost when treatment was discontinued. In patients treated for 144 weeks, benefits were maintained, with infrequent emergence of viral resistance.

Determinants for the occurrence of acute exacerbation of hepatitis B virus infection in Chinese patients after HBeAg seroclearance

This study was performed to determine the factors for predicting the occurrence of acute exacerbation of hepatitis B virus infection in HBeAg-negative patients. Two hundred and sixteen patients with known times of HBeAg seroclearance were recruited. Liver biochemistry and virologic markers were monitored. Precore and core promoter mutations were determined by a line probe assay. The median age at HBeAg seroclearance was 34.5 years. The median follow-up duration was 26.4 months. Fifty-six (27.9%) patients had acute exacerbations. By Cox regression analysis, male gender, older age, and core promoter mutations at the time of HBeAg seroclearance were independently associated with the occurrence of acute exacerbation after HBeAg seroclearance (P = 0.025, 0.018, and 0.001, respectively). Fourteen (7.0%) patients had HBeAg seroreversion within a median follow-up period of 11.6 months after HBeAg seroclearance. By Cox regression analysis, older age at HBeAg seroclearance was independently associated with the chance of HBeAg seroreversion (P = 0.01). We concluded that male patients with core promoter mutations and delayed HBeAg seroclearance had a higher cumulative chance of acute exacerbation in the HBeAg-negative phase. Patients with delayed HBeAg seroclearance had a higher frequency of HBeAg seroreversion.

HAART-related nephropathies in HIV-infected patients

There is no doubt that highly active antiretroviral therapy (HAART) has been the most important progress in the therapy of human immunodeficiency virus (HIV)-infected patients in the last decade. A growing number of observations suggest that the beneficial effects of HAART also include improvement of HIV-related renal complications. Consequently, the cohort of HIV-infected patients requiring HAART has increased and includes patients with preexisting nephropathies, whether related or unrelated to HIV infection. However, some antiretroviral drugs may have renal- and life-threatening side-effects, especially if underlying renal abnormalities exist. In this review, we focus on those aspects that require particular attention in preventing new health complications in HIV-infected patients.

Is Hepatitis B Immunoglobulin Prophylaxis Needed for Liver Transplantation in the Era of New Antivirals?

Chronic infection with hepatitis B virus (HBV) is one of the most common causes of cirrhosis of the liver and hepatocellular carcinoma worldwide, frequently requiring liver transplantation. Other nonliver organ transplants get infected de novo or through reactivation from previous active or inactive infections. With significant improvements in the surgical techniques and immunosuppressive regimens over the last 20 years, organ transplantation has become the most effective and lifesaving therapy for patients with chronic renal failure, cirrhosis, hepatocarcinoma, and heart failure. Until recently chronic HBV infection was considered a formal contraindication for liver transplantation, since recurrence of infection without prophylaxis occurs in 75% to 90% of the patients, with significant morbidity and mortality and few therapeutic alternatives. However, the introduction of hepatitis B immunoglobulin (HBIG) a decade ago to reduce the risk of reinfection of liver grafts, and more recently the availability of nucleoside analogues with few side effects and easy administration, have led to a dramatic improvement in patient outcomes with a risk of long-term HBV reinfection of less than 10% with combined HBIG and lamivudine prophylaxis. Chronic HBV infection in kidney, heart, and other organs has become a serious long-term problem and one of the most frequent and important comorbidities affecting graft and patient survival. Fortunately the introduction of nucleoside analogues allows significant control of viral replication and prevents progression of liver disease and other organ damage. In the present article we discuss the current indications for HBV prophylaxis and treatment prior to and after organ transplantation, as well as the most cost-effective way to apply different regimens to reduce side effects and improve survival and quality of life after transplantation.

Asian-Pacific consensus statement on the management of chronic hepatitis B: a 2005 update

BACKGROUND/AIMS

A large amount of new data on the treatment of chronic hepatitis B has become available such that the 2003 consensus statement requires revision and update.

METHODS

New data were presented, discussed and debated in an expert pre-meeting to draft a revision. The revised contents were finalized after discussion in a general meeting of APASL.

RESULTS

Conceptual background, including the efficacy and safety profile of currently available and emerging drugs, was reviewed. Nineteen recommendations were formed and unresolved issues and areas for further study were suggested.

CONCLUSION

The current therapy of chronic hepatitis B is modestly effective but not satisfactory. The development of new drugs and new strategies is required to further improve the outcomes of treatment.

HIV-1/hepatitis B coinfection

Reviews the epidemiology, natural history and the current status of treatment of HIV/hepatitis B coinfection.

Prophylaxis of hepatitis B virus recurrence after liver transplantation in carriers of lamivudine-resistant mutants

The combination of lamivudine and hepatitis B immunoglobulin (HBIG) reduces the risk of hepatitis B virus (HBV) recurrence after liver transplantation (LT). However, the efficacy of this strategy and the need for combined therapy with adefovir dipivoxil (ADV) in patients who select lamivudine-resistant strains (YMDD) before surgery is still unknown. Twenty-two patients treated with lamivudine (LAM) who underwent LT after YMDD-mutant selection were studied. In 13 patients, YMDD mutants were associated with an HBV DNA breakthrough greater than 5 log10 (group A: phenotypic resistance), and 11 were treated with ADV to decrease viral load before LT. In the remaining 9 patients who did not experience the viral breakthrough, YMDD mutants were detected only retrospectively in sera stored at the time of LT (group B: genotypic resistance). During 35 months of post-LT follow-up, none of the 11 patients of group A treated with ADV before and after surgery (in addition to HBIG and LAM) had HBV recurrence, and neither did any of the 7 subjects of group B treated with LAM before and after transplantation (in addition to HBIG). HBV recurred in 2 patients of group A (untreated with ADV before surgery and transplanted with an HBV DNA exceeding 5 log10) and in 2 subjects of group B (who spontaneously stopped HBIG after surgery). In carriers of YMDD mutants, the risk of post-LT HBV recurrence is low, provided that preemptive and prophylactic ADV (in addition to LAM and HBIG) treatment is used in highly viremic patients and prophylactic LAM (or ADV) and HBIG therapy is continued in low viremic patients.

Lamivudine vs lamivudine and interferon combination treatment of HBeAg(-) chronic hepatitis B

To determine whether combination treatment of HBeAg(-) chronic hepatitis B is beneficial we studied 78 patients with HBeAg(-), HBV DNA-positive chronic hepatitis B who were randomized to lamivudine, 100 mg, qd, for 12 months or lamivudine-interferon (9 MU, t.i.w.) in combination. In the combination arm, 2 months of lamivudine treatment preceded 10 months of combination treatment. Biochemical, virologic and histologic responses were assessed at the end of treatment, after six and a median 27 months of drug-free follow-up (short- and long-term follow-up, respectively). Virologic response was defined as undetectable HBV DNA with a hybridization assay and biochemical response as normal alanine aminotransferase (ALT). Change in HBV DNA was also assessed by real-time polymerase chain reaction (PCR). Presence of YMDD mutants at the end of treatment was investigated with a line probe assay. Both treatment regimes led to a median 2 log decline in HBV DNA levels. Virologic end of treatment responses were 90 and 92% with mono- and combination treatment, respectively. Corresponding virologic responses at short- and long-term follow-up were 59 and 54%, and 27 and 25%, respectively. Patients having a baseline HBV DNA value > or =200 pg/mL were more likely to relapse within 6 months off therapy than those patients with a baseline HBV DNA level <200 pg/mL (P = 0.041). YMDD mutants were observed in 53% of patients receiving lamivudine compared with 24% of patients receiving the combination regime (P = 0.017). In conclusion, efficacy of combination treatment is similar to lamivudine monotherapy. However, combination treatment decreases the development of YMDD mutant strains compared with lamivudine monotherapy.

Telbivudine: a new nucleoside analogue for the treatment of chronic hepatitis B

Telbivudine, beta-L-2'-deoxythymidine (LdT), is a new beta-L-nucleoside analogue with potent inhibitory activity against the hepatitis B virus. In in vitro studies and animal models, telbivudine has demonstrated potent and specific antiviral activity against hepatitis B. Additionally, in preclinical animal toxicology studies, telbivudine showed no adverse side effects or adverse effects on mitochondrial function. The promising results of the early in vitro and animal telbivudine studies prompted the development and initiation of Phase I and II human clinical trials. The Phase I clinical study demonstrated that end-of-treatment virological response rates were better for telbivudine recipients at multiple dosing levels as compared with placebo patients. The subsequent Phase IIb human clinical study demonstrated superior antiviral efficacy of telbivudine, significantly better ALT normalisation and better hepatitis B e-antigen loss as compared with lamivudine. Telbivudine was well tolerated with no identified safety issues. Virological breakthrough with telbivudine was significantly lower than with lamivudine.

Morphological and biochemical characterization of a human liver in a uPA-SCID mouse chimera

A small animal model harboring a functional human liver cell xenograft would be a useful tool to study human liver cell biology, drug metabolism, and infections with hepatotropic viruses. Here we describe the repopulation, organization, and function of human hepatocytes in a mouse recipient and the infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) of the transplanted cells. Homozygous urokinase plasminogen activator (uPA)-SCID mice underwent transplantation with primary human hepatocytes, and at different times animals were bled and sacrificed to analyze plasma and liver tissue, respectively. The plasma of mice that were successfully transplanted contained albumin and an additional 21 human proteins. Liver histology showed progressive and massive replacement of diseased mouse tissue by human hepatocytes. These cells were accumulating glycogen but appeared otherwise normal and showed no signs of damage or death. They formed functional bile canaliculi that connected to mouse canaliculi. Besides mature hepatocytes, human hepatic progenitor cells that were differentiating into mature hepatocytes could be identified within liver parenchyma. Infection of chimeric mice with HBV or HCV resulted in an active infection that did not alter the liver function and architecture. Electron microscopy showed the presence of viral and subviral structures in HBV infected hepatocytes. In conclusion, human hepatocytes repopulate the uPA(+/+)-SCID mouse liver in a very organized fashion with preservation of normal cell function. The presence of human hepatic progenitor cells in these chimeric animals necessitates a critical review of the observations and conclusions made in experiments with isolated "mature" hepatocytes. Supplementary material for this article can be found on the HEPATOLOGY website (http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Viral prophylaxis in organ transplant patients

Viral pathogens have emerged as the most important microbial agents having deleterious effects on solid organ transplant (SOT) recipients. Antiviral chemoprophylaxis involves the administration of medications to abort transmission of, avoid reactivation of, or prevent progression to disease from, active viral infection. Cytomegalovirus (CMV) is the major microbial pathogen having a negative effect on SOT recipients. CMV causes infectious disease syndromes, augments iatrogenic immunosuppression and is commonly associated with opportunistic superinfection. CMV has also been implicated in the pathogenesis of rejection. Chemoprophylactic regimens for CMV have included oral aciclovir (acyclovir) at medium and high doses, intravenous and oral ganciclovir, and the prodrugs valaciclovir (valacyclovir) and valganciclovir. CMV prophylactic strategies should be stratified, with the highest-risk patients receiving the most 'potent' prophylactic regimens. Herpes simplex virus (HSV) reactivation in SOT recipients is more frequent, may become more invasive, takes longer to heal, and has greater potential for dissemination to visceral organs than it does in the immunocompetent host. Prophylactic regimens for CMV are also effective chemoprophylaxis against HSV; in the absence of CMV prophylaxis, aciclovir, valaciclovir or famciclovir should be used as HSV prophylaxis in seropositive recipients. Primary varicella-zoster virus (VZV) after SOT is rare and most commonly seen in the paediatric transplant population because of VZV epidemiology. Zoster occurs in 5-15% of patients, usually after the sixth post-transplant month. Prophylactic regimens for zoster are neither practical nor cost effective after SOT because of the late onset of disease and low proportion of affected individuals. All SOT recipients should receive VZV immune globulin after contact with either varicella or zoster. Epstein-Barr virus has its most significant effect in SOT as the precipitating factor in the development of post-transplant lymphoproliferative disorders. Antiviral agents that could be effective are the same as those used for CMV, but indications for and effectiveness of prophylaxis are poorly established. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are important pathogens in the SOT population as indications for transplantation. So-called 'prophylaxis' for recurrent HBV and HCV after liver transplantation is controversial, suppressive rather than preventive, and potentially lifelong. Influenza infection after SOT is acquired by person-to-person contact. During epidemic periods of influenza, transplant populations experience a relatively high frequency of infection, and influenza may affect immunosuppressed SOT recipients more adversely than immunocompetent individuals. Antiviral medications for prevention of influenza are administered as post-exposure prophylaxis to SOT recipients, in addition to yearly vaccine, in circumstances such as influenza epidemics and nosocomial outbreaks, and after exposure to a symptomatic individual during 'flu season'.

Adefovir dipivoxil added to ongoing lamivudine therapy in patients with lamivudine-resistant hepatitis B e antigen-negative chronic hepatitis B

BACKGROUND

Long-term treatment with lamivudine is required to control viral replication in patients with hepatitis B e antigen-negative chronic hepatitis B, but is associated with a high rate of viral resistance. The role of adefovir dipivoxil in these patients has not been definitively evaluated.

AIM

To address the role of adefovir in the management of patients with lamivudine-resistant hepatitis B e antigen-negative chronic hepatitis B.

METHODS

Patients were assigned to receive adefovir 10 mg once daily plus ongoing lamivudine 100 mg once daily for 52 weeks. The primary end point was reduction in serum hepatitis B virus DNA level (hepatitis B virus DNA response). Secondary end points included the proportion of patients with undetectable hepatitis B virus DNA at week 52 (complete virological response) and the percentage of patients with normalization of alanine transferase level at week 52 (biochemical response).

RESULTS

A total of 49 consecutive patients were enrolled in this study. After 52 weeks of treatment, all patients had an hepatitis B virus DNA response and 57.1% had complete virological response. Biochemical response occurred in 75.6% of patients.

CONCLUSIONS

Administration of adefovir in patients with lamivudine-resistant chronic hepatitis B results in significant suppression of viral replication. Nevertheless, continuous therapy will probably be needed in order to maintain remission in these patients.

Long-term follow-up of chronic hepatitis B after the emergence of mutations in the hepatitis B virus polymerase region

Treatment of chronic hepatitis B has been greatly improved by the use of lamivudine, but mutations occur in the polymerase region of hepatitis B virus (HBV) and lamivudine-resistant mutants frequently develop. The emergence of lamivudine-resistant strains of HBV is a problem for treating chronic hepatitis B using lamivudine. We observed biochemical and virological changes in 15 patients with chronic hepatitis B for a median period of 29 months (range: 4-42 months) after the emergence of lamivudine-resistant mutants of HBV. Patterns of mutation of the polymerase gene were examined by sequencing the LLAQ motif in domain B and the YMDD motif in domain C. Exacerbation of liver dysfunction occurred in 14 (93.3%) of the 15 patients at a median of 4 months after the emergence of mutations. However, exacerbation of liver dysfunction was observed only in four patients (26.7%) at the time of appearance of the first mutations and in 80.0% of the patients at the time of appearance of the second mutations. Increase in serum alanine aminotransferase (ALT) levels was significantly greater at the time of appearance of second mutations (P = 0.0096). In most cases, wild-type HBV was mutated with the substitution of only rtM204I at first, and rtL180M/M204I mutations and then rtL180M/M204V mutations subsequently appeared. Further mutations of the polymerase region caused clinical deterioration. Thus as mutations emerge in the polymerase region, the clinical outcome deteriorates. Thus, monitoring the patterns of mutation of the polymerase gene is useful when using lamivudine for treating HBV.

Impact of interferon-alpha therapy on liver fibrosis progression in patients with HBeAg-negative chronic hepatitis B

The possible effect of interferon-alpha (IFNa) on liver fibrosis progression has not been adequately studied in chronic hepatitis B. We evaluated 147 patients with HBeAg-negative chronic hepatitis B who had > or =2 liver biopsies and had been treated with IFNa (n = 120) or had remained untreated (n = 27). The median interval between the two biopsies was 24 (12-160) months. All biopsies were scored blindly by a single liver histopathologist according to the classification of Ishak et al. (J Hepatol 1995; 22: 696-699). IFNa induced sustained biochemical response in 30, initial response and subsequent relapse in 57 and no response in 33 patients. Fibrosis improved in 17.5% of treated (sustained responders: 40%, relapsers: 9%, nonresponders: 12%) and 4% of untreated patients and worsened in 34% (sustained responders: 7%, relapsers: 40%, nonresponders: 48%) and 70% of cases, respectively (P = 0.002). The annual rate of fibrosis progression was worse in the untreated (0.427 +/- 0.119) than in treated patients (0.067 +/- 0.052, P = 0.001). However, the fibrosis progression rate in the untreated patients was not significantly different than the net fibrosis progression rate (after subtraction of IFNa duration) in nonresponders or relapsers. In multivariate analysis, worse fibrosis progression rate was associated with older age (P = 0.010), worse baseline grading score (P < 0.001), lower baseline fibrosis (P = 0.035) and the type of response to IFNa (P = 0.032). In conclusion, in HBeAg-negative chronic hepatitis B, IFNa significantly reduces the rate of fibrosis progression, but such an effect is mainly observed in patients with sustained biochemical responses. In relapsers and nonresponders, fibrosis benefit equals the treatment period. The strongest factor associated with fibrosis progression is the change in necroinflammatory activity.

Adefovir dipivoxil in chronic hepatitis B infection

Adefovir dipivoxil, an acyclic nucleotide analogue, is effective for the treatment of chronic hepatitis B in both hepatitis B e antigen (HBeAg)-positive and -negative patients, with improvement in liver histology, hepatitis B virus (HBV) DNA levels, alanine aminotransferase levels, and HBeAg seroconversion (for HBeAg-positive patients). It is also effective against lamivudine-resistant strains of hepatitis B mutations. It has been studied in pre- and post-liver transplant patients. Compared to lamivudine, adefovir dipivoxil is associated with a much lower risk of emergence of drug-resistant HBV. Adefovir-associated resistant virus is susceptible to lamivudine therapy. The recommended dose of adefovir dipivoxil 10 mg is associated with low risk of nephrotoxicity. Adefovir dipivoxil can be recommended as a first-line treatment but can also be used in patients with chronic hepatitis B infection who are failing lamivudine therapy.

Emerging treatments in chronic hepatitis B

Although the management of chronic hepatitis B has improved over the last decade, none of the available therapeutic agents, IFN-alpha, lamivudine and adefovir dipivoxil, can achieve sustained off-therapy responses in most cases. Therefore, several newer, mainly antiviral and immunomodulatory agents, are being evaluated. Pegylated IFN-alpha(2a) has been shown to be more effective than lamivudine or standard IFN-alpha monotherapy in achieving post-therapy biochemical and virological responses, and is expected to be licensed soon for the treatment of chronic hepatitis B. Newer antiviral agents, such as entecavir and telbivudine, appear to be quite effective initially, but their sustained off-therapy response rates remain unknown. The preliminary data of monotherapies with immunomodulatory agents, or of combination therapies, have been rather disappointing. Long-term maintenance treatment with antiviral agent(s) with good safety and tolerability profiles and low resistance rates appears to be the most realistic future therapeutic option for most chronic hepatitis B patients.

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Suppression of lamivudine-resistant B-domain mutants by adefovir dipivoxil in the woodchuck hepatitis virus model

Adult woodchucks (Marmota monax) chronically infected with woodchuck hepatitis virus (WHV) were treated orally with lamivudine (15 mg/kg per day) for 57 weeks. After 20 weeks of treatment a 2-3 log reduction in serum WHV DNA was detected. Serum titers of WHV then increased gradually, in the presence of lamivudine treatment, reaching pre-treatment values by week 40. Viral recrudescence was associated with development of mutations in the B domain of the WHV polymerase gene. Mutations observed in the highly conserved FLLA motif of the B domain were L564V, L565M, and A566T, with A566T being the most frequently observed. Beginning on week 57 of lamivudine treatment, one group (n = 3) was treated orally with adefovir dipivoxil at a dose of 15 mg/kg per day plus lamivudine, and a second group (n = 3) was treated with H2O placebo plus lamivudine. In woodchucks treated with adefovir dipivoxil, two had the A566T mutation, and one had both A566T and L565V. In the group maintained on lamivudine monotherapy, A566T alone was present in one animal, another carried both A566T and L565V, and in the third, no B-domain mutations were detected. There was a 4.5 log reduction in serum WHV DNA after 12 weeks of treatment with the adefovir/lamivudine combination, while in the lamivudine monotherapy controls, WHV DNA decreased by only 0.83 log (P > 0.001). A slight recurrence in serum titers of WHV DNA was observed one week after withdrawal of adefovir treatment but no further increase in viral load was observed during the remainder of the 12-week post-treatment follow-up period. The results demonstrate that supplemental adefovir dipivoxil treatment is effective in suppressing replication of lamivudine-resistant B-domain mutants in the woodchuck model of hepatitis B virus infection.

Antifibrotic therapy in chronic liver disease

The response to injury is one of wound healing and, subsequently, fibrosis. This response is generalized, occurring in diverse organ systems. Injury and wounding in the liver ultimately lead to cirrhosis in many patients (although not all patients), and are the result of many different diseases. The fact that various diseases result in cirrhosis suggests a common pathogenesis. Study over the past 2 decades has shed considerable light on the pathogenesis of fibrosis and cirrhosis. A growing body of literature indicates that the hepatic stellate cell is a central component in the fibrogenic process. Stellate cells undergo a transformation during injury that has been termed activation. Activation is complex and multifaceted, but one of its most prominent features is the synthesis of large amounts of extracellular matrix, resulting in deposition of scar or fibrous tissue. The fibrogenic process is dynamic; it is noteworthy that even advanced fibrosis (or cirrhosis) is reversible. The best antifibrotic therapy is treatment of the underlying disease. For example, eradication of hepatitis B or C virus can lead to the reversal of fibrosis. In situations in which treating the underlying process is not possible, specific antifibrotic therapy is desirable. A number of specific antifibrotic therapies have been tried, but have been met with poor or mediocre success. However, elucidation of the mechanisms responsible for fibrogenesis, with particular emphasis on stellate cell biology, has highlighted many putative novel therapies. This article emphasizes mechanisms underlying fibrogenesis, and reviews current antifibrotic therapies as well as potential future approaches.

Activity of adefovir dipivoxil against all patterns of lamivudine-resistant hepatitis B viruses in patients

One hundred and thirty-one post-liver transplantation patients with chronic hepatitis B and failing lamivudine therapy with detectable serum hepatitis B virus (HBV) deoxyribonucleic acid by hybridization assays or > or =1 x 10(6) copies/mL by polymerase chain reaction, and elevated alanine transaminase levels despite continuous lamivudine, were enrolled in an open-label study of adefovir dipivoxil. The B and C domains of HBV polymerase were sequenced for baseline samples to determine the presence of lamivudine resistance mutations. The results showed that 98% of the samples had tyrosine-methionine-aspartate-aspartate (YMDD) mutations, indicating a strong correlation between the above clinical definition of lamivudine treatment failure and the presence of YMDD mutations. In addition to the rtM204V/I and the rtL180M mutations, the mutation rtV173L was identified in 19% of patients. Four major patterns of lamivudine-resistant HBV were identified: rtL180M + rtM204V (60%), rtV173L + rtL180M + rtM204V (19%), rtM204I (9%) and rtL180M + rtM204I (9%). Treatment with adefovir dipivoxil showed similar antiviral efficacy in patients with lamivudine-resistant virus from all four patterns.

A Practical Approach to Management of Chronic Hepatitis B

Chronic hepatitis B (CHB) is one of the important public health problems worldwide. Major advances have been made in the treatment of CHB during the past several years. This article systemically reviews advances in the application of HBV DNA quantitation and three approved drugs for HBV treatment, and presents an updated and practical clinical approach to managing CHB. Highly sensitive PCR-based quantitation of HBV DNA makes it possible to precisely determine pre-treatment HBV load and monitor HBV DNA response during treatment. HBV DNA level, HBeAg status, degree of hepatic histological activity and fibrosis, and serum transaminases are the most important parameters in determining indication, regimen, and duration of HBV treatment. Although interferon alfa-2b, lamivudine, and adefovir are all approved as initial HBV treatment, understanding the advantages and advantages of each agent is important in choosing the best treatment for each individual patient with CHB.