LB80380: a promising new drug for the treatment of chronic hepatitis B

Hepatitis B virus is a significant cause of liver cirrhosis and hepatocellular carcinoma in patients with chronic infection. Higher levels of viral load are associated with increased risk of developing liver-related complications. The current available oral therapies suppress viral replication through their action on the hepatitis B virus polymerase. As treatment with oral nucleoside/nucleotide analogues is associated with the development of drug-resistant mutations, there is continuing research for newer and more potent antiviral agents to reduce the chance of drug resistance. LB80380, a prodrug, is an oral nucleotide analogue that inhibits viral replication by incorporation into the viral DNA. Antiviral activity against wild-type virus and virus with drug-resistant mutations was demonstrated in Phase II trials, with significant reduction of viral load in patients treated with LB80380. LB80380 was also shown to be safe and well tolerated.     

Clevudine: a promising therapy for the treatment of chronic hepatitis B

Chronic hepatitis B virus (HBV) infection, affecting ～ 350 million people worldwide, is associated with significant morbidity and mortality. In the past 10 years, hepatitis B therapy research has led to a multitude of available antiviral therapies: IFN-α, pegylated IFN-α_2a, lamivudine, adefovir, entecavir, telbivudine and tenofovir. To further improve reductions in viral load and resistance profiles, development of new HBV therapeutic strategies has been an important focus. One such therapy is clevudine, an analogue of the β-L configuration. Clevudine is already licensed in Korea for anti-HBV therapy (Bukwang Pharmaceuticals, Seoul, Korea). Unique to clevudine is its ability to maintain antiviral activity following discontinuation of therapy. Typically, hepatitis B treatment requires continuous therapy to prevent reactivation. Sustained response is uncommon except in hepatitis B antigen (HBeAg)-positive patients who developed HBeAg seroconversion. This article reviews chronic HBV and its therapy options. Specifically, it describes clevudine's potent and sustained antiviral activity as observed in vitro and in vivo.     

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.     

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

Infection with hepatitis B virus (HBV) is extremely widespread - it infects two billion people out of the six billion world population. It is estimated that between 350 and 400 million people are chronically infected with HBV. Chronic HBV infection leads to development of complications, such as cirrhosis and hepatocellular carcinoma (HCC), which arise in 15-40% of patients. HBV-related liver disease and its complications result in approximately one million deaths each year. The ultimate goals of chronic hepatitis B (CHB) therapy are decreases in the incidence of cirrhosis, end-stage liver disease and HCC. The following six medications are currently approved by the U.S. Food and Drug Administration for the treatment of CHB: interferon (INF)-alpha2b, pegylated INF-alpha2a, lamivudine, adefovir dipivoxil, entecavir and, recently, telbivudine. Interferon therapy has many contraindications and commonly causes multiple intolerable adverse effects. Lamivudine therapy leads to increased development of resistant mutations with each year of use. Entecavir, a new guanosine nucleoside analogue with specific activity against HBV DNA polymerase, represents a third agent within the nucleoside/nucleotide HBV polymerase inhibitor class. It has 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 clinical trials, entecavir was superior to lamivudine in all primary endpoints in both nucleoside-naive and lamivudine-refractory hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients. Preliminary data support entecavir efficacy in patients with cirrhosis and HIV/HBV coinfected patients. No resistance occurred after two years of entecavir therapy in nucleoside-naive patients. Up to 9% resistance developed in patients with documented prior lamivudine resistance during 96 weeks of entecavir therapy. Currently, entecavir should be considered a first- or second-line treatment option for the management of HBeAg-positive or -negative nucleoside-naive or lamivudine-refractory CHB patients.     

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

Telbivudine, β-L-2′-deoxythymidine (LdT), is a new β-L-nucleoside analogue with potent inhibitory activity against the hepatitis B virus. In invitro 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 invitro and animal telbivudine studies prompted the development and initiation of Phase I andII 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.     

Natural products as promising drug candidates for the treatment of hepatitis B and C

Hepatitis B virus （HBV） or hepatitis C virus （HCV） infections are a major threat worldwide. Combination therapy of interferon-α and ribavirin is currently the treatment of choice for HCV-infected patients. However, this regimen is only effective in approximately 50% of patients and provokes severe side-effects. Numerous natural alternatives for treating HCV have been suggested. Deoxynojirimycin and its derivatives are iminosugars which exert anti-HCV activity by inhibiting α-glucosidases. A non-immunosuppressive derivate of cyclosporine A, NIM811, exerts anti-HCV activity by binding to cyclophilin. Other natural products with promising anti-HCV activity are 2-arylbenzofuran derivatives, Mellein, and pseudoguaianolides. For HBV treatment, several drugs are available, specifically targeting the virus polymerase （lamivudine, entecavir, telbivudine, and adefovir dipivoxil）. The efficacy of these drugs is hampered by the development of resistance due to point mutations in the HBV polymerase. Due to drug resistance and adverse side-effects, the search for novel drugs is mandatory. Wogonin, ellagic acid, artemisinin and artesunate, chrysophanol 8-O-β-D-glucoside, saikosaponin C, and protostane triterpenes are active against HBV. Natural products need to be investigated in more detail to explore their potential as novel adjuncts to established HBV or HCV therapy.     

Entecavir: a new nucleoside analog for the treatment of chronic hepatitis B infection

BACKGROUND: Chronic hepatitis B infection carries considerable risk for the development of cirrhosis and hepatocellular carcinoma. Treatment options are increasing but are limited to interferon alfa-2b, pegylated interferon alfa-2a, lamivudine, adefovir dipivoxil, and entecavir. Entecavir, a nucleoside analog, is the newest oral antiviral approved in the United States for treatment of chronic hepatitis B. OBJECTIVE. To review the available data for entecavir regarding its pharmacology, pharmacokinetics, safety, efficacy, and clinical use. METHODS. A MEDLINE, EMBASE, and Cochrane search of the English-language literature from January 1997-May 2006 was performed. Preapproval studies provided by the manufacturer and abstracts from recent scientific meetings on infectious disease and hepatology were also reviewed. RESULTS. Three phase III clinical trials representing more than 1600 subjects established the superior efficacy and equivalent safety of entecavir compared with lamivudine for treating patients who are hepatitis B early antigen (HBeAg) positive, HBeAg negative, or refractory to lamivudine. Entecavir resistance has not occurred in nucleoside-na?ve patients but may develop in those who already possess lamivudine resistance mutations. CONCLUSION. Trial results, along with previously published response rates for adefovir dipivoxil and interferon monotherapy, make entecavir the preferred first-line treatment option for patients with chronic hepatitis B who are nucleoside na?ve, HBeAg positive or negative, and have compensated liver disease. Both entecavir and adefovir dipivoxil maintain activity against hepatitis B virus in patients with chronic hepatitis B who are refractory to lamivudine, and both agents are reasonable first-line treatment options. Longer trials involving nucleoside-na?ve, lamivudine-refractory patients are needed to determine entecavir's optimal treatment duration, long-term safety, and durability of response, including rate of resistance.     

Entecavir: a potent new antiviral drug for hepatitis B

Entecavir, a new deoxyguanine nucleoside analogue, is a selective inhibitor of the replication of the hepatitis B virus. In vitro this compound has proven to be far more effective than other nucleoside analogues. In animal models, an impressive reduction of serum viral DNA has been observed with covalently closed circular DNA and hepatitis B viral core antigen negativity in liver biopsy specimens. In clinical studies, entecavir revealed excellent suppression of hepatitis B virus replication without significant side effects or evidence of mitochondrial toxicity. Until now, no entecavir-resistant viral mutants have been described. Prolonged therapy as well as prophylactic therapy, for example, in liver transplant recipients, is feasible and not limited by breakthrough infections. Data on entecavir therapy for treatment of nucleoside-naive, wild-type hepatitis B virus is being generated in Phase III clinical trials worldwide for both hepatitis B envelope antigen-positive and -negative subpopulations, as well as in lamivudine-resistant patients. Based on mechanism and potency of interferon and entecavir, clinical trials with combination therapy are eagerly awaited.     

Entecavir: a potent new antiviral drug for hepatitis B

Entecavir, a new deoxyguanine nucleoside analogue, is a selective inhibitor of the replication of the hepatitis B virus. In vitro this compound has proven to be far more effective than other nucleoside analogues. In animal models, an impressive reduction of serum viral DNA has been observed with covalently closed circular DNA and hepatitis B viral core antigen negativity in liver biopsy specimens. In clinical studies, entecavir revealed excellent suppression of hepatitis B virus replication without significant side effects or evidence of mitochondrial toxicity. Until now, no entecavir-resistant viral mutants have been described. Prolonged therapy as well as prophylactic therapy, for example, in liver transplant recipients, is feasible and not limited by breakthrough infections. Data on entecavir therapy for treatment of nucleoside-naive, wild-type hepatitis B virus is being generated in Phase III clinical trials worldwide for both hepatitis B envelope antigen-positive and -negative subpopulations, as well as in lamivudine-resistant patients. Based on mechanism and potency of interferon and entecavir, clinical trials with combination therapy are eagerly awaited.     

抗乙型肝炎病毒药物研发现状

从1983年到2005年11月．被美国FDA批准用于慢性乙型肝炎治疗的有5种药物．但其在疗效和不良反应等方面均有一定的局限性。目前．一批用于治疗慢性乙型肝炎的新药正处于研发阶段，其中已进入临床试验后期的药物以核苷类似物为主。本文对已上市及进入临床试验的治疗乙型肝炎的药物进行了总结．并对已完成Ⅱ期临床试验的治疗慢性乙型肝炎的药物进行了评述。     

Telbivudine for the treatment of chronic hepatitis B

The hepatitis B virus (HBV) has a complex natural history and causes a wide spectrum of disease. Choices of therapy depend on a number of factors predictive of treatment response, clinical circumstances and stage of disease, and the likelihood and consequences of resistance to treatment. Telbivudine (beta-L-2'deoxythymidine) is a thymidine analogue that belongs to a new class of beta-L-configuration nucleoside analogues with specific activity against hepadnavirus. Phase III studies of telbivudine versus lamivudine in hepatitis B e antigen (HBeAg) and anti-HBe have been completed. In HBeAg-positive patients, HBV DNA was not detectable by polymerase chain reaction (PCR) assay in 56% of the HBeAg-positive patients receiving telbivudine after two years of treatment. In HBeAg-negative patients, at two years, HBV DNA was undetectable by PCR in 82% of HBeAg-negative patients (versus 52% of lamivudine recipients). Patients who were PCR-negative after 24 weeks were less likely to develop resistance. HBeAg seroconversion rates were also greatest in patients whose HBV DNA was undetectable at 24 weeks. These results are promising and could be used to devise a strategy to utilize combination therapy or to adjust therapy if an inadequate early viral response is observed. However, resistance is a potential shortcoming of the use of single agents for the treatment of HBV.     

Lamivudine for the treatment of chronic hepatitis B

Lamivudine (Zeffix, Epivir, GlaxoSmithKline) is the most important recent advance in the treatment of chronic hepatitis B in both adults and children. It is the only available oral treatment and has an excellent safety profile, which makes it even more attractive. It increases the rate of hepatitis B e antigen (HBeAg) loss and seroconversion in compensated chronic HBeAg-positive carriers, with subsequent improvement of histology at a similar rate as IFN-alpha. Lamivudine is mostly active in patients with elevated transaminases and is not effective in compensated patients with quiescent disease. Long-term follow-up studies are still required to evaluate long-term benefits, including those on hepatitis B surface antigen (HBsAg) seroconversion rate and disease evolution control. In decompensated patients, the drug can stabilise and improve liver function, allowing the patient to wait safely for transplantation. Patients may improve to such an extent that transplantation can be postponed. Combined with hepatitis B immunoglobulin (HBIG), lamivudine considerably decreases the risk of graft re-infection after transplantation. It is also active in chronic HBeAg-negative hepatitis patients, for whom IFN is less efficient. The major drawback is the emergence of the tyrosine-methionine-aspartate-aspartate (YMDD) mutation, which prevents further efficacy of the drug and may lead to flares of hepatitis. Due to the questions the YMDD mutation raises and because hepatitis B is a complex disease, indications for treatment must be established with care and only by physicians with expert knowledge of the disease, the drug and YMDD mutation-related issues.     

Lamivudine for the treatment of chronic hepatitis B

Lamivudine (Zeffix^®, Epivir^®, GlaxoSmithKline) is the most important recent advance in the treatment of chronic hepatitis B in both adults and children. It is the only available oral treatment and has an excellent safety profile, which makes it even more attractive. It increases the rate of hepatitis B e antigen (HBeAg) loss and seroconversion in compensated chronic HBeAg-positive carriers, with subsequent improvement of histology at a similar rate as IFN-α. Lamivudine is mostly active in patients with elevated transaminases and is not effective in compensated patients with quiescent disease. Long-term follow-up studies are still required to evaluate long-term benefits, including those on hepatitis B surface antigen (HBsAg) seroconversion rate and disease evolution control. In decompensated patients, the drug can stabilise and improve liver function, allowing the patient to wait safely for transplantation. Patients may improve to such an extent that transplantation can be postponed. Combined with hepatitis B immunoglobulin (HBIG), lamivudine considerably decreases the risk of graft re-infection after transplantation. It is also active in chronic HBeAg-negative hepatitis patients, for whom IFN is less efficient. The major drawback is the emergence of the tyrosine-methionine-aspartate-aspartate (YMDD) mutation, which prevents further efficacy of the drug and may lead to flares of hepatitis. Due to the questions the YMDD mutation raises and because hepatitis B is a complex disease, indications for treatment must be established with care and only by physicians with expert knowledge of the disease, the drug and YMDD mutation-related issues.     

Adrenomedullin: a new and promising target for drug discovery

Adrenomedullin (AM) is a 52 amino acid peptide that plays a critical role in several diseases such as hypertension, cancer, diabetes, cardiovascular and renal disorders, among others. Interestingly, AM behaves as a protective agent against some pathologies, yet is a stimulating factor for other disorders. Thus, AM can be considered as a new and promising target for the design of non-peptidic modulators that could be useful for the treatment of those pathologies, by regulating AM levels or the activity of AM. A full decade on from its discovery, much more is known about AM molecular biology and pharmacology, but this knowledge still needs to be applied to the development of clinically useful drugs.     

Adrenomedullin: a new and promising target for drug discovery

Adrenomedullin (AM) is a 52 amino acid peptide that plays a critical role in several diseases such as hypertension, cancer, diabetes, cardiovascular and renal disorders, among others. Interestingly, AM behaves as a protective agent against some pathologies, yet is a stimulating factor for other disorders. Thus, AM can be considered as a new and promising target for the design of non-peptidic modulators that could be useful for the treatment of those pathologies, by regulating AM levels or the activity of AM. A full decade on from its discovery, much more is known about AM molecular biology and pharmacology, but this knowledge still needs to be applied to the development of clinically useful drugs.     

Referral for chronic hepatitis C treatment from a drug dependency treatment setting

To examine rates and predictors of referral for hepatitis C virus (HCV) treatment and preliminary treatment outcomes in injecting drug users (IDUs) receiving opioid replacement treatment, a prospective clinical audit was undertaken in an inner city Sydney drug dependency treatment practice between December 2002 and November 2005. The majority of IDUs (178/237; 75%) were HCV antibody positive, of whom 170 were HCV treatment naïve with no absolute treatment contraindications. Among these 170 patients, 121 (71%) had chronic HCV. Based on risk factors for HCV disease progression, 63 of 121 (52%) chronic HCV patients were targeted for referral; these patients were older, had higher alanine aminotransferase levels and longer estimated duration of HCV infection. Of these 63 patients, 43 were referred to a hepatitis treatment clinic, and 27 attended during the audit period. Patients who attended for treatment assessment were more likely to have genotype 2 or 3 (p < 0.001), but socio-behavioural factors were similar. Liver biopsy was performed in 20 patients, with moderate or greater fibrosis in 18 patients. Of 14 patients commenced on pegylated interferon-alpha and ribavirin therapy, one ceased treatment due to non-response, 10 have completed treatment, all with an end-of-treatment (n = 4) or sustained virological response (n = 6), and treatment is ongoing in three. The development of HCV treatment referral criteria has allowed prioritisation of patients for referral, potentially halving those that require early assessment. Preliminary HCV treatment outcomes are encouraging and highlight the potential for reducing liver disease burden in this patient population.     

替比夫定联合阿德福韦酯治疗慢性耐药型乙型肝炎的Meta分析

目的系统评价替比夫定联合阿德福韦酯治疗慢性耐药型乙型肝炎的疗效及安全性。方法计算机检索Pub Med、EMBASE、CNKI、VIP、CBM、Cochrane图书馆和万方数据库,检索时间截止到2014年4月,纳入相关随机对照试验(RCT)并评价质量,提取有效数据进行Meta分析。结果有6项随机对照临床试验符合入选标准,Meta分析结果显示,和单用替比夫定相比,联合用药治疗阿德福韦酯耐药的慢性乙型肝炎,在治疗12周和24周时均有较高的HBV-DNA转阴率、HBe Ag转阴率和丙氨酸氨基转移酶(ALT)复常率(P<0.05)。对替比夫定耐药的慢性乙型肝炎患者,联合用药和单用阿德福韦酯相比,在治疗48周时有较高的HBV-DNA转阴率和ALT复常率(P<0.05),但两者的HBe Ag转阴率差异无统计学意义(P>0.05)。联合用药治疗和单药治疗均未见严重不良反应。结论基于当前临床证据,替比夫定联合阿德福韦酯治疗慢性耐药型乙型肝炎具有较高的疗效和安全性。     

Evaluating anti-viral drug selection and treatment duration in HBeAg-negative chronic hepatitis B: a cost-effectiveness analysis

Background  Several anti-viral treatments are now available for HBeAg-negative chronic hepatitis B (CHB), but the clinical and economic outcomes of potential treatment strategies and durations are unclear.
Aim  To examine the clinical and economic outcomes of potential treatment strategies and durations for HBeAg-negative CHB.
Methods  We conducted a cost-utility analysis from a payer perspective over a lifetime time horizon. Disease progression probabilities, costs and quality of life data were derived from the literature. We evaluated 5-year, 10-year, lifetime and 5 on–1 off treatment durations. For each of these treatment durations, we evaluated initial therapy with entecavir, lamivudine or adefovir, with addition of adefovir or entecavir for patients who developed virological breakthrough because of resistance (12 strategies total).
Results  Increasing treatment duration improved quality-adjusted life-years (QALYs) and was generally cost-effective for all three drugs. However, a 5 on–1 off strategy was the most cost-effective: lifetime vs. 5 on–1 off entecavir had an ICER of $148 200/QALY. In probabilistic sensitivity analyses, entecavir 5 on–1 off was the preferred strategy over the range of commonly reimbursed cost-effectiveness thresholds. Lifetime treatment was preferred to a 5 on–1 off strategy, if treatment durability was <10%.
Conclusion  The results of our analysis suggest that in HBeAg-negative CHB infection, a 5 on–1 off treatment strategy with entecavir improves health outcomes in a cost-effective manner compared to alternative strategies.     

Current pharmacotherapy for the treatment of chronic hepatitis B

The virological profile of infection with the hepatitis B virus (HBV) is changing in many parts of the world from the classical hepatitis B e antigen (HBeAg)-positive serological pattern to a HBeAg-negative pattern, linked to the replacement of wild-type HBV by HBV variants with mutations in the core-promoter and in the precore region that prevent the secretion of HBeAg. The wild-type HBV disease is characterised by steady levels of alanine aminotransferase (ALT) and high HBV-DNA levels, responding relatively well to IFN treatment (3 – 5 MU/day or 10 MU every other day for 16 weeks), which induces anti-HBe seroconversion and normalises ALT levels in ～ 30% of the adults, with a minimal risk of relapse. Pegylated-IFN appears to have superior efficacy over conventional IFN-α. Mutant-type disease (anti-HBe-positive/HBeAg-negative) is less responsive to IFN given for 6 – 12 months. This has led to the use of novel nucleoside analogues, of which the prototype is lamivudine. The response to lamivudine therapy shares with IFN a rapid decline in ALT accompanied by an improvement in histology; at variance with IFN, in HBeAg-positive chronic hepatitis B (CHB) there is delayed seroconversion to anti-HBe which accumulates over time, the switch to anti-HBs is more rare and in the long-term, the activity of the drug is abolished by the emergence of viral mutations (YMDD-motif mutants) that may rekindle the disease. The combination of IFN plus lamivudine may be more efficacious than IFN or lamivudine monotherapy. Lamivudine therapy needs to be prolonged in HBeAg-negative CHB. Short-term lamivudine-therapy is highly efficacious in preventing HBV reinfection in liver transplants. Recent data suggest that long-term IFN therapy (24 months) may achieve a response in 30% of HBeAg-negative patients. The advent of adefovir, an analogue of adenosine monophosphate, may provide a safer alternative to lamivudine in the control of HBV disease; the drug is well-tolerated and treatment raises drug-resistant mutants in < 2% of the patients over 2 years of therapy. Adefovir provides rescue therapy against YMDD mutants raised by lamivudine therapy.