Successful rescue therapy with tenofovir in a patient with hepatic decompensation and adefovir resistant HBV mutant

Efficacy of nucleoside analogues for hepatitis B virus-related liver failure: A network meta-analysis

The purpose of this study was to compare the efficacy of nucleoside analogues (NAs) in the treatment of HBV-related liver failure. The data of patients with HBV-related liver failure treated with nucleoside analogues were used to conduct a network meta-analysis. A total of 1660 patients from 12 articles about the efficacy of lamivudine, entecavir, telbivudine and tenofovir for HBV-related liver failure treatment were recruited in the study. The highest two- and three-month survival rate was recorded for patients using tenofovir. The end-stage liver disease (MELD) score and mortality in patients undergoing tenofovir treatment were the lowest. Patients treated with telbivudine had the highest one-month survival rate. Patients receiving enticavir therapy showed the lowest HBV DNA level. Our results indicate that tenofovir may be the best therapy for the treatment of HBV-related liver failure compared to other nucleoside analogues (including lamivudine, entecavir and telbivudine) and non-NAs treatment.

Prevalence of Hepatitis C Virus Genotypes Among Patients in Countries of the Eastern Mediterranean Regional Office of WHO (EMRO): A Systematic Review and Meta-Analysis

CONTEXT

Hepatitis C virus (HCV) infection is a major global public health issue. The Eastern Mediterranean regional office (EMRO) of the world health organization (WHO) seems to have one of the highest prevalence rates worldwide, with at least 21.3 million HCV-infected patients.

OBJECTIVES

The aim of the present study was to review systematically all epidemiological data related to the prevalence of HCV genotypes in infected patients in EMRO countries.

DATA SOURCES

A systematic search was conducted of peer-reviewed journals indexed in electronic databases (PubMed, Scopus, ISI, PakMediNet, and IMEMR, and Persian-specific databases including SID, Iran Medex, and MagIran).

STUDY SELECTION

A systematic search was performed with temporal limits (papers published between January 2000 up to June 2015), regarding the prevalence and distribution of HCV genotypes in EMRO countries.

DATA EXTRACTION

The prevalence rates of HCV genotypes were pooled by metan command in Stata 14. Statistical heterogeneity was explored using the I-square at the 5% significance level. Publication bias was assessed, graphically and statistically, by funnel plot and Begg and Egger tests.

RESULTS

A total of 563 records were identified through the electronic search. Of these records, 134 studies comprising 67681 HCV-infected individuals were included in the meta-analysis. In Iran, subtype 1a was the predominant subtype with a rate of 42% (95% CI, 39 - 46), followed by subtype 3a, 35% (95% CI, 31 - 38). In Pakistan, Subtype 3a was the most common subtype with a rate of 56% (95% CI, 49 - 62), followed by subtype 3b, 10% (95% CI, 7 - 12). In Saudi Arabia and Egypt, genotype 4 was the most prevalent genotype with a rate of 65% (95% CI, 59 - 72) and 69% (95% CI, 36 - 100) respectively. In Tunisia and Morocco, subtype 1b was the most common subtype with a rate of 69% (95% CI, 50 - 88) and 32% (95% CI, 7 - 56) respectively.

CONCLUSIONS

The genotype distribution of HCV takes diverse patterns in EMRO countries. Genotypes 1 and 3 were predominant in Iran and Pakistan, while genotype 4 and 1 were the most common genotypes in the Middle East Arab countries and North African Arab countries. Understanding the genotypes of HCV can help policy makers in designing good strategies for treatment.

Antiviral therapy in patients with hepatitis B virus-related cirrhosis

Antiviral therapy can lead to biochemical remission, histological improvement, and even complete reversibility of liver cirrhosis in patients with hepatitis B virus-related cirrhosis, thereby significantly reducing the incidence of hepatic decompensation, hepatocellular carcinoma and liver disease-related death. Interferon alpha is not contraindicated in compensated cirrhosis and can be used in finite treatment for 6 or 12 months. Long-term treatment with nucleoside/nucleotide analogues is recommended for both compensated and decompensated cirrhosis. Biochemical and virological changes should be carefully monitored during antiviral treatment to promptly find viral breakthrough and prevent hepatitis B recurrence and liver failure. In addition, hepatocellular carcinoma is required to be screened in all cirrhotic patients.

Management of end-stage liver disease in chronic hepatitis B

The consequences of chronic hepatitis B virus infection include hepatocellular carcinoma and liver cirrhosis. Effective antiviral therapy in patients with hepatitis B with advanced liver disease with viral suppression and sustained HBeAg seroconversion (where applicable) may abort hepatic decompensation, diminish hepatocellular risk, and reduce the risk of viral recurrence after transplantation. Overt hepatic decompensation is an indication for referral to a transplant center.

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

Objective:

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

Data Sources:

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

Study Selection and Data Extraction:

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

Data Synthesis:

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

Conclusions:

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

[Antiviral efficacy of lamivudine/adefovir combination therapy in chronic hepatitis b patients with resistance to lamivudine and adefovir consecutively]

BACKGROUND/AIMS

The aim of this study was to elucidate the antiviral efficacy of lamivudine (LMV)-adefovir (ADV) combination therapy in chronic hepatitis B patients who showed resistance to LMV and ADV consecutively.

METHODS

A retrospective review was performed in eighteen patients with chronic hepatitis B who developed virologic breakthroughs during LMV-ADV sequential mono-therapy and treated with LMV-ADV combination therapy.

RESULTS

The median duration of follow up was 17 months (range, 6-27) after the start of LMV-ADV combination therapy. Mean HBV DNA level in log10 IU/mL was 6.08+/-0.95, 4.05+/-1.66, 3.17+/-1.58, 3.18+/-2.16, and 2.35+/-1.52 at 0, 3, 6, 12, and 24 months, respectively. Sixteen patients (88.9%) showed HBV DNA reduction below detection limit (<20,000 IU/mL). HBeAg seroconversion was observed in one patient (7.1%) after 8 months of combination therapy. Virologic breakthrough occurred in only one patient after 21 months of combination therapy. Viral rebound occurred in two patients at 12 months and 14 months of combination therapy. Normalization of serum ALT was achieved in twelve patients (66.7%). Primary non-response was observed in two cases (11.1%).

CONCLUSIONS

LMV-ADV combination treatment was effective in 88.9% of patients with resistance to LMV and ADV in a short-term follow up. It may be applied as a bridge therapy until another effective antiviral regimen becomes available.

Tenofovir and its potential in the treatment of hepatitis B virus

Recent literature is reviewed about treatment of chronic hepatitis B virus (CHB), focusing on tenofovir disoproxil fumarate (TDF; Viread^®), among the nucleotide and nucleoside analogs. TDF pharmacokinetics and pharmacodynamics, activity in respect of hepatitis B virus (HBV) multi-drug-resistant mutations, efficacy in treatment-naïve and treatment-experienced patients, and side effects are described. The most predictive response factors to TDF therapy are discussed and all available combination therapies to optimize clinical outcome in the various patient profiles are analyzed, such as compensated and/or decompensated cirrhotic patients. The use of TDF in pregnancy, and prophylaxis after exposure to HBV and post-liver transplantation are also evaluated.

Polymorphism rtQ215H in primary resistance to adefovir dipivoxil in hepatitis B virus infection: a case report

The benefit of lamivudine (LAM) in hepatitis B virus (HBV) infection is compromised by the progressively increasing emergence of drug-resistant mutant strains. Although the addition of adefovir dipivoxil (ADV) usually induces complete suppression of viral replication, primary non-response to ADV in LAM resistant patients has been reported in a variable percentage of cases. Here we report a case of a patient with HBV infection and hepatocellular carcinoma who started LAM therapy and subsequently developed virological breakthrough. The patient was given ADV, but HBV-DNA negativisation was not reached. However, HBV clearance was obtained when the patient was switched from ADV to tenofovir. Virological evaluations showed two well-known LAM-related mutations (rtL180M and rtM204I) in addition to reverse-transcriptase rtQ215H. This is the first case suggesting that this mutation may have an impact on viral replication. Finally, we also report that rtQ215H is responsive to tenofovir.

Tenofovir Disoproxil Fumarate Tablets

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursinginservices. A comprehensive target drug utilization evaluation (DUE) is also provided each month. With a subscription, the monographs are sent in print and are also available online. Monographs can be customized to meet the needs of a facility. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The February 2009 monograph topics are on fospropofol disodium, rufinamide, eltrombopag, fenofibric acid, and carisbamate. The DUE is on rufinamide.

Management of patients with decompensated hepatitis B virus associated [corrected] cirrhosis

1. Hepatitis B virus replication is associated with a severe outcome in patients with decompensated cirrhosis. 2. Viral suppression induced by antivirals results in a clinical improvement that allows liver transplantation to be delayed or avoided. 3. Early treatment intervention is mandatory in patients with decompensated cirrhosis because of the delay in the restoration of liver functions. 4. Lamivudine is no longer the drug of choice because the initial enthusiasm has been tempered by the high rate of resistance development. 5. Early add-on therapy with adefovir allows us to rescue lamivudine resistance, but its use may be limited by nephrotoxicity. 6. Studies are ongoing with the newer generation of antivirals (telbivudine, tenofovir, entecavir, and emtricitabine) in monotherapy or in combination to determine the best strategy for achieving rapid and prolonged suppression of viral replication. These improved strategies should enhance treatment success enough to obtain clinical stabilization, to delay or prevent the need for transplantation, and to reduce the risk of hepatitis B virus recurrence on the graft.AASLD.

Tenofovir plus lamivudine as rescue therapy for adefovir-resistant chronic hepatitis B in hepatitis B e antigen-positive patients with liver cirrhosis

BACKGROUND/AIMS

There is no consensus on the management of patients with adefovir (ADV)-resistant hepatitis B virus (HBV) infection. The aim of this study was to investigate whether tenofovir disoproxil fumarate (TDF) combined with lamivudine (LMV) is effective and safe in patients with resistance to or non-response to ADV.

METHODS

Six patients with HBV-related cirrhosis, viral breakthrough during LMV therapy and viral breakthrough or non-response during ADV therapy were treated daily with TDF plus LMV for at least 6 months. The HBV DNA level, alanine aminotransferase (ALT), the Child-Pugh score and serum creatinine were monitored. Genotypic LMV- or ADV-resistant mutations were measured in stored samples.

RESULTS

In five of six patients, ADV-resistant mutations at rt181 or rt236 were detected during ADV therapy. At 6 months of starting TDF/LMV combination, HBV DNA levels became undetectable (detection limit, 400 copies/ml) in four of six patients. Within 12 months, HBV DNA levels became undetectable in all patients, and ALT levels were normalized in four of six patients. These responses persisted up to the end of the observation period (median duration 16.5 months, range 6-21 months). The Child-Pugh scores improved in two of three patients with hepatic decompensation. No significant changes in serum creatinine were observed.

CONCLUSION

Our data demonstrated that TDF plus LMV safely and markedly suppressed HBV replication in patients with resistance to or non-response to ADV. This study suggests that this combination may be a promising rescue therapy for these patients, particularly those with liver cirrhosis or pre-existing LMV resistance.

Role of tenofovir in the treatment of chronic HBV infection

Nucleoside analogues revolutionized the treatment of chronic HBV infection and have become the most important therapeutic option within the last decade. Currently, the nucleoside analogues lamivudine, telbivudine and entecavir, and the nucleotide analogue adefovir dipivoxil, are licensed. Tenofovir disoproxil fumarate (TDF) is another acyclic nucleotide analogue that has been successfully used in the treatment of HIV-infected patients, but has demonstrated significant antiviral activity in wild-type and lamivudine-resistant HBV infections. The use of TDF 300 mg/day leads to marked suppression of HBV replication below the detection limit in different patients groups with HBV mono- or HIV/HBV co-infection in most instances, and a remarkably high rate of hepatitis B e antigen loss and even hepatitis B surface antigen loss was found in small, uncontrolled studies. Belonging to the substance class of acyclic nucleotide analogues, TDF is not cross-resistant to nucleoside analogue resistance-associated mutations. In equal dosages, TDF has comparable antiviral potency as compared with its congender adefovir dipivoxil, but in clinical studies exhibits higher antiviral efficacy and generates a higher genetic barrier against the development of genotypic HBV resistance due to its approximately 24-fold higher dosage. Owing to the numerous newly developed compounds and as a consequence of the emerging problem of drug resistance, treatment concepts for chronic hepatitis B will certainly be modified in the future. Because of its quite favorable antiviral and safety properties, TDF will likely be highly regarded in the management of HBV infections in the future.

Sustained virological and biochemical responses to lamivudine and adefovir dipivoxil combination in a chronic hepatitis B infection despite mutations conferring resistance to both drugs

Background

Sequential monotherapies of nucleotide analogs used in chronic hepatitis B treatment can lead to the selection of a resistance mutation to each antiviral drug.

Case presentation

A patient with chronic hepatitis B was successively treated with lamivudine monotherapy, lamivudine-adefovir dual therapy, adefovir monotherapy and again with an adefovir-lamivudine dual therapy. Lamivudine-associated mutations (rtL180M and rtM204V/I) followed by adefovir-associated mutations (rtN236T and rtA181V) emerged during the two monotherapy regimens. Despite the presence of rtM204V/I, rtA181V, and rtN236T mutations at the beginning of the second dual therapy, sustained biochemical and virological responses have been observed thus far after 23 months.

Conclusion

This case illustrates that rtM204V/I, rtA181V, and rtN236T resistance mutations can coexist in a patient but do not preclude the recycling of lamivudine and adefovir in combination therapy, when no other therapeutic choices are available.

Antiviral treatment of chronic hepatitis B virus infections: the past, the present and the future

A decade ago, standard therapy against chronic hepatitis B virus infections only consisted of lamivudine or IFN-alpha. Treatment with lamivudine and IFN has been compounded by, respectively, the emergence of drug-resistant virus strains and the appearance of serious side effects. In the last 10 years, hepatitis B treatment has made much progress. Several treatments are now licensed for the treatment of patients with chronic hepatitis B and others are under development. Here, we provide an overview of the potential and mode of action of anti-HBV agents that are currently available, and/or may become available in the near future. Foremost among these newer compounds are adefovir dipivoxil, entecavir and telbivudine.

Review article: Success and failure of nucleoside and nucleotide analogues in chronic hepatitis B

BACKGROUND

Strong suppression of viral replication and normalization of alanine aminotransferase is feasible with nucleos(t)ide analogues. It is estimated viral replication and liver inflammation can be controlled in 90% of patients with chronic hepatitis B with the current available treatments.

AIM

To review the studies currently available on the management of chronic hepatitis B with nucleos(t)ide analogues.

RESULTS

Although very potent, nucleos(t)ide analogues are not effective in every patient. Some factors are known to influence treatment outcome, but many host and viral factors are still unknown. Stopping rules have to be defined to assess treatment efficacy in an early stage and change the regimen. Discontinuation of nucleos(t)ide analogues is often followed by reactivation of HBV. Data on the risk factors for relapse are necessary in order to decide if treatment can be safely discontinued. Another major drawback of nucleos(t)ide analogues is the emergence of resistance. The efficacy of compounds for the treatment of mutant virus and the impact of cross-resistance is largely unknown. The use of combination therapy to prevent resistance looks promising, but has to be proven.

CONCLUSIONS

HBV has become a treatable disease, however much research is needed to optimize treatment for individual patients and treatment failures.

Hepatitis B and end-stage liver disease

Hepatitis B virus (HBV) is the most common cause of chronic hepatitis and end-stage liver disease worldwide. Untreated, chronic hepatitis B acquired early in life results in cirrhosis, liver failure, or hepatocellular carcinoma in up to 40% of individuals. Until recently, the options for a patient who had end-stage hepatitis B cirrhosis were severely limited, but during the past 15 years great strides have been made in prevention and treatment of hepatitis B cirrhosis. This article reviews recent advances in the understanding of the natural history, prevention, and medical management of HBV-related end-stage liver disease.

In vitro activity of 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]-pyrimidine against multidrug-resistant hepatitis B virus mutants

The susceptibilities of drug-resistant hepatitis B virus (HBV) mutants to lamivudine, adefovir, tenofovir, entecavir, and 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]-pyrimidine (PMEO-DAPym), a novel acyclic pyrimidine analogue, were assessed in vitro. Most drug-resistant mutants, including multidrug-resistant strains, remained sensitive to tenofovir and PMEO-DAPym. Therefore, the latter molecule deserves further evaluation for the treatment of HBV infection.

Progress in the treatment of chronic hepatitis B: long-term experience with adefovir dipivoxil

Most chronic hepatitis B patients do not undergo a curative response to interferon-alpha or nucleoside/nucleotide-based regimens and require long-term therapy. Long-term safety, efficacy and resistance profiles of hepatitis B virus (HBV) drugs are therefore crucial issues for patient management. Adefovir dipivoxil is a nucleotide prodrug indicated for the treatment of patients with hepatitis B e antigen positive or hepatitis B e antigen negative chronic hepatitis B, lamivudine-resistant HBV infection, HBV infection pre- or post-liver transplantation, or HlV co-infection. Long-term data from clinical trials of up to 5 years duration of adefovir dipivoxil have recently become available and are reviewed here. These data demonstrate that adefovir dipivoxil therapy results in sustained efficacy and safety in the majority of patients after multiple years of treatment. The efficacy of adefovir dipivoxil in treating lamivudine-resistant HBV and the delayed emergence of adefovir resistance are key factors contributing to the durable response achieved in broad groups of chronic hepatitis B patients.

Where does adefovir stand amongst newly developed antivirals: from pharmacology to virology

Adefovir, an acyclic nucleotide analog of adenosine monophosphate, has demonstrated potent activities against several viruses in vitro. Since 2002, the diester prodrug of this molecule, adefovir dipivoxil, has been approved as a well-tolerated and efficacious treatment for chronic hepatitis B. It is the first nucleotide analog to be approved for this indication and it is now challenged by several other molecules that also inhibit hepatitis B virus replication. In this article, we analyze the strengths and limitations of adefovir in the context of hepatitis B treatment and consider the other alternatives in the treatment of this difficult-to-treat chronic disease. Adefovir dipivoxil has offered a real opportunity for patients who developed lamivudine resistance and were facing a therapeutic deadlock; the next challenge for clinicians will be to offer the best therapeutic strategy to limit the inexorable selection of resistant strains.

Intracellular metabolism and in vitro activity of tenofovir against hepatitis B virus

Tenofovir is an acyclic nucleotide analog with activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV). Tenofovir disoproxil fumarate (tenofovir DF), a bis-alkoxyester prodrug of tenofovir, is approved for the treatment of HIV and is currently being developed to treat chronic hepatitis B. In this report, we further characterize the in vitro activity of tenofovir against HBV as well as its metabolism in hepatic cells. We show that tenofovir is efficiently phosphorylated to tenofovir diphosphate (TFV-DP) in both HepG2 cells and primary human hepatocytes. TFV-DP has a long intracellular half-life (95 h) and is a potent and competitive inhibitor of HBV polymerase (Ki = 0.18 microM). Tenofovir has a 50% effective concentration of 1.1 microM against HBV in cell-based assays, and potency is improved > 50-fold by the addition of bis-isoproxil progroups. Tenofovir has previously demonstrated full activity against lamivudine-resistant HBV in vitro and clinically. Here we show that the major adefovir resistance mutation, rtN236T, confers three- to fourfold-reduced susceptibility to tenofovir in cell culture; the clinical significance of this susceptibility shift has not yet been determined. The rtA194T HBV polymerase mutation recently identified in tenofovir DF-treated HIV/HBV-coinfected patients did not confer in vitro resistance to tenofovir as a single mutation or in a lamivudine-resistant viral background. Overall, the antiviral and metabolic profile of tenofovir supports its development for the treatment of chronic hepatitis B.

Antiretroviral therapy for hepatitis B virus-HIV-coinfected patients: promises and pitfalls

Coinfections with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) are common globally. HIV infection modifies the course of HBV infection by increasing rates of chronicity, prolonging HBV viremia, and increasing liver-related morbidity. To minimize the emergence of HIV and/or HBV resistance, as well as the emergence of liver enzyme flares, the treatment of both infections should be coordinated. Lamivudine or emtricitabine monotherapy readily selects resistant strains in the YMDD motif of the polymerase gene. Adefovir and tenofovir are fully active in the presence of YMDD mutations [corrected] If HBV treatment can be deferred until combination antiretroviral therapy for HIV infection is needed, the combination of tenofovir plus lamivudine or emtricitabine provides potent HBV therapy and a solid backbone for HIV combination antiretroviral therapy, and it likely decreases the emergence of HBV resistance.

In Vitro Susceptibility of Adefovir-Associated Hepatitis B Virus Polymerase Mutations to other Antiviral Agents

Background

Adefovir dipivoxil is a nucleotide prodrug approved for the treatment of chronic hepatitis B. During clinical trials, ADV-associated mutations were observed in 0, 3, 11, 18 and 29% of patients after 48, 96, 144, 192 and 240 weeks of therapy, respectively. Hepatitis B virus (HBV) polymerase mutations associated with virological breakthrough to ADV include rtA181V and rtN236T, which occur alone or in combination. The rtA181T mutation has also been observed at low frequency, alone or in combination with rtN236T.

Methods

To investigate the in vitro activity of adefovir and other anti-HBV agents against these mutants, we generated five stable cell lines that each expressed one of the following HBV mutants: rtN236T, rtA181V, rtA181V+rtN236T, rtA181T+rtN236T and rtA181T. Using these cell lines, we quantified in vitro changes in drug susceptibility for eight nucleotide/nucleoside analogues.

Results

The rtN236T mutant had 7-fold resistance to adefovir but remained sensitive to entecavir, telbivudine and torcitabine (≤3.2-fold reduced susceptibility). The A181V mutant had 4.3-fold resistance to adefovir and had reduced susceptibility to multiple other agents ranging from 3.2-fold (tenofovir) to >191-fold (clevudine). The A181V+rtN236T double mutant was the most highly resistant showing 18-fold resistance to adefovir and higher levels of resistance to other tested drugs with the exception of tenofovir (10-fold reduced susceptibility). Our results and preliminary clinical data suggest that patients with rtN236T or rtA181V remain susceptible to tenofovir, entecavir and lamivudine. Further clinical data are necessary to precisely define in vitro cutoffs indicative of clinically-relevant resistance, particularly for drugs in development such as emtricitabine, telbivudine, torcitabine and clevudine.