Medical therapy of patients affected by HBeAg-negative chronic hepatitis B

Five agents are currently approved for the treatment of chronic hepatitis B: standard interferon-alpha (IFN-alpha), pegylated interferon-alpha 2a (PEG-IFN-alpha 2a), lamivudine, adefovir and entecavir. Each agent has inherent limitations. IFN and PEG-IFN-alpha 2a are effective in a minority of patients and have frequent side effects that limit their tolerability. The efficacy of lamivudine is limited by the emergence of drug-resistant hepatitis B virus (HBV) mutants, restricting its utility as a long-term therapy. Adefovir is well tolerated and associated with a low incidence of resistance but its antiviral effect is not optimal. Entecavir, which has been recently registered, has a more potent anti-viral effect but its long term efficacy and resistance profile is still not known. These antivirals induce a sustained response after withdrawal of therapy in only a minority of patients and therefore the treatment needs to be indefinitely administered in the majority of patients. After a brief summary of the natural history of chronic hepatitis B in order to understand the indications and the objectives of therapy, this review focuses on treatment of HBeAg-negative chronic hepatitis B with IFN and PEG-IFN-alpha 2a.     

Hepatitis B e antigen-negative chronic hepatitis B: natural history and treatment

Hepatitis B e antigen (HBeAg)-negative chronic hepatitis B evolves in the natural history of chronic hepatitis B virus (HBV) infection linked with selection of nonproducing HBeAg but replication-competent HBV mutants, and may have a potentially severe and progressive course. Effective suppression of HBV replication is the main therapeutic target. Sustained off-therapy responses are rare with treatment of finite duration, except perhaps for interferon-based therapies, which induce such responses in a sizeable, yet small proportion of patients. Eventually, the majority of patients will be treated with long-term oral antiviral therapy, which improves patients' outcome but is associated with progressively increasing rates of viral resistance. The long-term resistance profile of adefovir is significantly better than that of lamivudine (LMV), whereas data for entecavir currently are limited to 2 years, with resistance developing in LMV-resistant but not in treatment-na?ve patients. Combination therapy with adefovir added to LMV in LMV-resistant patients is extremely effective; cases of adefovir-resistance have not been reported to date.     

Advances in therapy for chronic hepatitis B

Two agents are currently approved for the treatment of chronic hepatitis B: interferon alfa and lamivudine. Each agent has inherent limitations for use in the treatment of chronic hepatitis B. Interferon alfa is effective in a small number of patients and has serious side effects that limit its tolerability. The efficacy of lamivudine is limited by the emergence of drug-resistant hepatitis B virus (HBV) mutants, restricting its utility as a long-term therapy for chronic hepatitis B. As a result, a large proportion of chronic hepatitis B patients continue to be in need of a safe and efficacious therapy. This article provides an integrated analysis of the safety and efficacy of a new nucleotide analogue, adefovir dipivoxil, based on emerging data from recent studies. The study groups include patients with hepatitis B e antigen (HBeAg)-positive and HBeAg-negative chronic hepatitis B; lamivudine-resistant patients with compensated liver disease; lamivudine-resistant patients coinfected with the human immunodeficiency virus (HIV); and lamivudine-resistant pretransplant and posttransplant patients with decompensated liver disease. Adefovir dipivoxil 10 mg/d demonstrated potent anti-HBV activity consistently across this broad range of patient populations and was well-tolerated. Adefovir dipivoxil's effects include rapid and sustained virological, serological, histological, and biochemical responses, with minimal adverse effects. Significant histological improvement was seen in all patient subgroups at 48 weeks.     

Extended lamivudine treatment in patients with chronic hepatitis B enhances hepatitis B e antigen seroconversion rates: results after 3 years of therapy

A study in Chinese patients with chronic hepatitis B showed that treatment with lamivudine for 1 year significantly improves liver histology and enhances hepatitis B e antigen (HBeAg) seroconversion compared with placebo. Fifty-eight patients from this 1-year study have received long-term treatment with lamivudine 100 mg; the outcome of 3 years of lamivudine is reported here. Before treatment, all patients had detectable HBeAg. HBeAg seroconversion (HBeAg-negative, anti-HBe-positive), hepatitis B virus (HBV)-DNA suppression, alanine transaminase (ALT) normalization, emergence of YMDD variant HBV, liver histology, and long-term safety were assessed. After 3 years of continuous treatment with lamivudine 100 mg daily, 40% (23 of 58) of patients achieved HBeAg seroconversion. In patients with baseline serum ALT >2 x upper limit of normal (ULN), the rate of HBeAg seroconversion was 65% (17 of 26). Median serum HBV-DNA concentrations were below the level of detection, and median ALT concentrations were within the normal range throughout 3 years of treatment. YMDD variant HBV emerged in 33 of 58 (57%) patients during the 3 years, of whom 9 (27%) achieved HBeAg seroconversion (6 after emergence of YMDD variant HBV). ALT levels and histologic scores after emergence of YMDD variant HBV did not show major deterioration. Lamivudine was well tolerated during 3 years of therapy. In conclusion, these data in Chinese patients with chronic hepatitis B show enhanced seroconversion rates with extended lamivudine treatment. Up to two thirds of patients with moderately elevated pretreatment ALT achieved HBeAg seroconversion after 3 years of therapy.     

Treatment of hepatitis B e antigen-negative patients

Opinion statement Hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) occurs at the late phase in hepatitis B virus (HBV) infection’s natural history. The disease is characterized by progressive liver damage due to variants with mutations in the precore/core promoter region that reduce or abolish HBeAg expression. Chronic HBeAg-negative disease’s prognosis is poor, with only rare incidences of spontaneous remission. Recent studies in Europe, Asia, and the United States all have reported an increased prevalence of HBeAg-negative and a decreased prevalence of HBeAg-positive chronic hepatitis; this may be related to increased awareness, decrease in new HBV infections, and aging of existing carriers. The end point of therapy for HBeAg-negative CHB patients is difficult to assess. In most studies, HBV DNA suppression and normalization of serum alanine aminotransaminase levels have been used to indicate therapeutic response. Six drugs currently are licensed for the treatment of CHB infection. These are the immunomodulatory agents (conventional interferon-α-2b and pegylated interferon-α-2a) and the nucleoside/nucleotide analogues (lamivudine, adefovir dipivoxil, entecavir, and telbivudine). Sustained treatment response rates generally are poor due to the high probability of relapse, particularly following nucleoside/nucleotide analogue therapy. As not all patients can tolerate or will respond to interferon-based therapy, maintenance therapy with nucleoside/nucleotide therapy is the alternative. However, this latter approach can lead to development of viral resistance and long-term safety concerns.     

Treatment of chronic hepatitis B: case selection and duration of therapy

Hepatitis B viral (HBV) infection is a major health burden in the Asia-Pacific region. The seriousness of chronic hepatitis B (CHB) is often realized at a late stage. The resultant morbidity and mortality from cirrhosis complications is considerable, with a high human cost. The most affected patients are men aged 40 years or older. Two decades ago, the prognosis for the 300 million "Australia antigen"-positive people (people with chronic HBV infection) was gloomy, with no effective intervention. Twenty years on, research and development have changed their outlook. Chronic hepatitis should now be diagnosed early, at the asymptomatic stage. Proper assessment and judicial introduction of therapy can suppress replication of HBV and resolve liver inflammation, thereby preventing the silent progression of chronic liver disease to end-stage cirrhosis. Interferon (IFN) monotherapy has been available for nearly 20 years, but various limitations restrict its general application. Injection-based therapies are inconvenient, the response rate is low (33% hepatitis B e antigen (HBeAg) seroconversion rate among optimal cases), side-effects are many, and some serious, and the cost is unaffordable for most people. However, in non-cirrhotic patients with mild to moderate disease activity, IFN is still a worthwhile option because the treatment course is shorter, mutation seems less of a problem and most responses are permanent and reduce or abolish late complications. Lamivudine, an oral nucleoside analog with potent antiviral effects, has been approved in many countries. Daily dosing of 100 mg reduces serum HBV-DNA to below detectable levels within 6 weeks. In HBeAg-positive patients, approximately 16% of treated patients seroconverted with the first year. This was associated with significant improvement in liver histology. Long-term treatment induces further HBeAg seroconversion, but overall clinical benefit is undermined by continuous emergence of drug-resistant YMDD mutants. In an Asian multicentre study, 58 patients on 5 years lamivudine therapy showed annual cumulative HBeAg seroconversion rates at 1, 2, 3, 4 and 5 years of 22, 29, 40, 47 and 50%, respectively. The best predictor of response is pretreatment alanine aminotransferase (ALT). Among patients with ALT > 2x the upper limit of normal (ULN), annual HBeAg seroconversion is increased to 38, 42, 65, 73 and 77%, respectively. However, emergence of YMDD mutants occurred at a cumulative rate of 15, 38, 55, 67 and 69%, respectively. The impact of this emergence on disease activity is unpredictable. Thus, while continued disease suppression, or even HBeAg seroconversion, still occurred in some patients, in others hepatitis may relapse and liver failure has been reported despite continuation of lamivudine. While the duration of lamivudine therapy is difficult to define, the best strategy may be to define only active CHB with major ALT elevation (par-ticularly ALT > 5x ULN) for a duration of 1 year or less. Lamivudine can be stopped in responders. The response is durable in approximately 80% of responders. Non-responders should be monitored closely for rebound off treatment. Therapy can be re-instituted if ALT is over 5x ULN. Management of patients with YMDD mutants can be challenging, but there is no clear evidence to recommend stopping or continuing lamivudine, or to add other possible effective agents, such as adefovir dipivoxil. More data are required to help draw up guidelines. Hepatitis B e antigen-negative CHB has been less well studied. Both IFN and lamivudine can suppress disease activity, but permanent responses are few. Without a distinct marker as an end-point for response, the duration of treatment is even more difficult to define. Quantitative polymerase chain reaction for low viral levels may give a clue, but definitive studies are required. Monotherapy is clearly not the answer for the majority of CHB patients with active disease. Combination therapy has the theoretical advantage of additional or synergistic efficacy. Preliminary results on IFN and lamivudine are promising and further clinical trials are ongoing. Emtricitabine (FTC), adefovir dipivoxil, entecavir, BL-thymidine (L-dT), DAPD, clevudine (l-FMAU), thymosin, therapeutic vaccines and various herbal medicines are potential candidates. Antiviral action in conjunction with immune modulation may have a better chance of eradicating HBV and its cccDNA in the hepatocytes as the basis for an eventual successful outcome. The key points are: (i) approved therapeutic agents for chronic hepatitis B (CHB) are IFN, lamivudine and thymosin (in a few countries only); (ii) indications for IFN therapy are viremia in compensated CHB patients with moderately raised ALT; (iii) lamivudine has broader therapeutic indications: it is effective in subgroups of CHB patients with compensated or decompensated liver diseases, but generally works better if patients have raised ALT; (iv) lamivudine has a potent suppressive action on HBV replication, including HBeAg-negative variants, but cannot eliminate cccDNA; this is the reason for the relapse of disease after discontinuing treatment, unless HBeAg seroconversion is obtained; (v) successful use of lamivudine aims at HBeAg seroconversion or profound suppression of HBV-DNA to serum levels of less than 100 000 viral copies/mL, in order to prevent emergence of drug-resistant YMDD mutants (which commences from 6 months onward); (vi) YMDD mutants may cause a flare of hepatitis, resulting in deterioration of liver histology and, occasionally, liver failure; (vii) combination therapy of lamivudine with IFN (standard or pegylated) or other nucleoside analogs should be the next advance. Preliminary data from IFN and lamivudine combination therapy show some promise, but there are conflicting results.     

Combination and newer therapies for chronic hepatitis B

Worldwide the need for effective therapy for chronic hepatitis B is similar to that for chronic hepatitis C. Current licensed treatment for chronic hepatitis B (interferon (IFN)-alpha, lamivudine) does not significantly alter the natural history of the disease because the frequency of sustained response is too low; however, a sustained response to antiviral therapy improves survival. Conversion of active chronic hepatitis B to the inactive hepatitis B carrier state (persistently HBeAg-negative, HBV-DNA < 10(5) copies/mL and alanine aminotransferase (ALT) normal) is the major therapeutic goal. If present 6-12 months after stopping treatment, a sustained response is assumed. Clinical benefit is also likely if HBV-DNA levels < 10(5) copies/mL and ALT normality are being maintained long-term by antiviral therapy. New drugs are adefovir, entecavir, and pegylated IFN. The two nucleoside analogs are active against lamivudine-resistant hepatitis B and are as yet not associated with resistance. Peg-IFN has higher efficacy than standard IFN; its tolerance is similar. Combination therapy appears most effective: IFN-lamivudine combination for induction of a sustained response, and lamivudine-adefovir for long-term antiviral therapy. Uncertainty exists whether the additional effect outweighs the burden of adverse effects and cost. Chronic hepatitis B affects a rather heterogeneous patient population. Differentiation based on HBeAg status is fading with emergence of categorization based on disease stage and immune competence.     

The cost-effectiveness of long-term antiviral therapy in the management of HBeAg-positive and HBeAg-negative chronic hepatitis B in Singapore

The purpose of this study was the economic evaluation of short-duration treatments of chronic hepatitis B (CHB) and longer duration antiviral treatment for up to 5 years. Two 10-health state Markov models were developed for hepatitis B e antigen (HBeAg)-positive and HBeAg-negative CHB patients respectively. The perspective of this economic evaluation was the Singapore healthcare system and CHB patient. The models followed cohorts of HBeAg-positive and HBeAg-negative CHB patients, respectively, over a period of 40 years, by which time the majority of the cohorts would have died if left untreated. Costs and benefits were discounted at 5% per annum. Annual rates of disease progression and the magnitude of treatment effects were obtained from the literature, with a focus on data obtained in Asian patients and meeting the criteria for therapy as described in internationally recognized management guidelines. Short-course therapy with alpha-interferon, or 1-year treatment with pegylated interferon alpha-2a, lamivudine or adefovir had limited impact on disease progression. In contrast, treatment of CHB with antiviral therapy for 5 years substantially decreased the rate of disease progression. Treatment with lamivudine for 1-year is highly cost-effective compared with no treatment of CHB but has limited effect on reducing the rate of disease progression. Compared with 1-year treatment with lamivudine, sequential antiviral therapies for up to 5 years (i.e. lamivudine plus adefovir on emergence of lamivudine resistance or adefovir plus lamivudine on emergence of adefovir resistance) are highly cost-effective by international standards. These conclusions are robust to uncertainties in model inputs and are consistent with the findings of other recently published studies.     

Treatment of chronic hepatitis B with the combination of pegylated interferon with lamivudine

Several agents are currently approved for the treatment of chronic hepatitis B: interferon alpha (IFN), pegylated interferon-α (PEG IFN), lamivudine, adefovir, and entecavir. Each agent has inherent limitations. IFN is effective in a minority of patients and has frequent side effects that limit its tolerability. Large randomized controlled trials have demonstrated the efficacy of PEG IFN in the treatment of chronic hepatitis B. The efficacy of lamivudine is limited by the emergence of drug-resistant hepatitis B virus (HBV) mutants, restricting its utility as a long-term therapy. Adefovir is well tolerated and is associated with low incidence of resistance, but its antiviral effect is not optimal. Entecavir has a high antiviral effect and is well tolerated. However, its long term efficacy and resistance profile are not yet determined. Lamivudine, adefovir and entecavir have the advantages of oral administration and excellent safety profiles. However, theyinduce a sustained response after withdrawal of therapy in only a minority of patients, and therefore, the treatment needs to be indefinitely administered in most patients. IFNs have two mechanisms of action: (i) direct antiviral effect by inhibiting synthesis of viral DNA and by activating antiviral enzymes; and (ii) exaggeration of the cellular immune response against hepatocytes infected with HBV. PEG IFN, administered for 48 weeks, gives an overall sustained response rate of approximately 30%. Two large randomized controlled trials have conducted to registration of PEG IFN-α-2a in the treatment of chronic hepatitis B.     

Treatment of chronic hepatitis B: Evolution over two decades

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

Clinical experience with lamivudine

Lamivudine, an oral nucleoside analogue, has demonstrated efficacy against the hepatitis B virus (HBV) in both HBeAg-positive and HBeAg-negative patients with chronic hepatitis B. Treatment with lamivudine is safe and well tolerated and induces a virological and biochemical response in most patients within a short time. Significant histological improvement was seen in clinical trials after 52 weeks of lamivudine treatment. However, durable posttreatment remission of chronic hepatitis B has not been shown to occur in a significant number of lamivudine-treated patients. To maintain the response to treatment, therefore, long-term therapy is required. Prolongation of therapy, however, is associated with the emergence of HBV resistance to lamivudine in most patients. This is accompanied by virological rebound and reversal of the initial therapeutic response, and sometimes by exacerbation of hepatitis. The need remains for effective, safe, and tolerable oral agents with durable activity against HBV.     

Nucleoside analogues for chronic hepatitis B: antiviral efficacy and viral resistance

Nucleoside analogues have been recently introduced in the management of chronic hepatitis B virus (HBV) infection. They mainly act by inhibition of HBV polymerase activity resulting in decrease of viral replication. They are administered orally, and most of them have an excellent tolerance and safety profile. Lamivudine is the only nucleoside analogue licensed for chronic hepatitis B. It has potent activity against HBV, and a 12-month course achieves clearance of hepatitis B e antigen (HBeAg) in 20-30% of HBeAg-positive patients and both biochemical and virological remission in more than 65-70% of HBeAg-negative chronic hepatitis B patients. Famciclovir and ganciclovir are less effective, whereas other nucleoside or nucleotide analogues, such as adefovir, entecavir, and emtricitabine, are currently under evaluation. Prolonged effective antiviral therapy is required for eradication of chronic HBV infection, but long-term treatment with nucleoside analogues has been found to be associated with progressively increasing rates of viral resistance because of emergence of resistant HBV mutant strains. Virological breakthroughs usually develop after the first 6 months of lamivudine monotherapy, and their rate ranges between 15% and 30% at 12 months and exceeds 50% after 3 yr of therapy. Resistant HBV mutant strains harbor point mutations in the HBV polymerase gene and predominantly in the well-conserved YMDD motif. Although resistant HBV strains may have impaired replication capacity compared with the wild HBV, their clinical significance has not been completely clarified yet. No significant biochemical or clinical event may develop in some cases, whereas severe biochemical breakthroughs with or without deterioration of liver function may develop in others. To date, there is no proven effective therapy for the resistant HBV mutant strains, although adefovir and entecavir seem to be interesting candidates.     

Diagnosis and management of pre-core mutant chronic hepatitis B

Chronic hepatitis due to pre-core hepatitis B virus (HBV) mutants presents as hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). HBeAg-negative CHB represents a late phase in the natural course of chronic HBV infection that develops after HBeAg loss and seroconversion to anti-HBe. It is usually associated with pre-core stop codon mutation at nucleotide 1896 (mainly selected in non-A HBV genotypes), but also with other pre-core changes or with mutations in the basic core promoter region (mainly in HBV genotype A). In chronic HBV infections, pre-core mutants can be detected both in patients with HBeAg-negative CHB and in inactive hepatitis B surface antigen (HBsAg) carriers. The diagnosis of HBeAg-negative CHB is based on HBsAg positivity, HBeAg negativity, and mainly on increased alanine aminotransferase (ALT) and serum HBV-DNA levels and exclusion of other causes of liver disease. The differential diagnosis between patients with CHB and inactive HBsAg carriers can be made only by close follow-up of aminotransferase activity and viraemia levels, although the cut-off level of serum HBV DNA has not been definitely determined. IgM anti-HBc levels have also been suggested as an index that increases the diagnostic accuracy for transient hepatitis flares, while liver biopsy confirms the diagnosis and evaluates the severity of the liver disease. Interferon-alpha (IFN-alpha) and lamivudine are the two drugs that have been tried, mainly in the management of HBeAg-negative CHB. A 12-month course of IFN-alpha achieves sustained biochemical remission in about 20% of patients, which has been associated with improvement in the long-term outcome of this subset. A 12-month course of lamivudine is rather ineffective, maintaining remission in less than 15% of patients after cessation of therapy. Long-term lamivudine is associated with progressively increasing rate of virological and subsequent biochemical breakthroughs due to YMDD mutants, with approximately 30% of patients remaining in remission in the third year of therapy. Several other antiviral agents are currently being evaluated in this setting with combined regimens being the most reasonable step for the near future.     

Assessment and management of chronic hepatitis B

An understanding of the natural history of CHB is critical for the management of the liver disease. Three clinical patterns with different clinical outcomes are recognized: HBeAg-positive CHB, HBeAg-negative CHB,and inactive CHB. Patients with elevated aminotransferase levels and HBV DNA greater than 105 viral copies per mL in serum and with features of chronic hepatitis on liver biopsy are candidates for therapy regardless of HBeAg status. Multiple host and viral factors and safety profiles of current therapies need to be considered carefully before recommending therapy.There appears to be no role for HBV genotyping in the management of patients. Three antiviral agents are approved for use against CHB infection:IFN-a, lamivudine, and adefovir. Efficacy is moderate at best and is limited by the poor tolerability of IFN and the development of resistance, coupled with concerns regarding the long-term safety with nucleoside analogs. Several new nucleoside and nucleotide analogs and novel agents are at various stages of development as potential therapies for CHB. The ideal compound would be one that is active against all replicative intermediates of the virus and has a low toxicity profile. Despite current shortcomings, the future of therapy for HBV is promising, as newer therapeutic options are being developed based on an understanding of the HBV life cycle.     

Advances in the diagnosis and treatment of the infection by the hepatitis B virus

Infection by the hepatitis B virus (HBV) is a significant cause of morbidity and mortality, mainly due to evolvement to cirrhosis and hepatocellular carcinoma. The prevalence and genotypic distribution of HBV infection has marked geographic differences. HBV infection is a very dynamic process, with a phase of immune tolerance and high viral replication, followed by HBeAg clearance, not always accompanied by complete suppression of HBV replication. The latter situation corresponds to negative HBeAg hepatitis, which represents a group relatively resistant to therapy. The three approved drugs for the treatment of HBV infection (interferon alpha, lamivudine and adefovir) have limited efficacy. Relapses are more common with lamivudine and adefovir, requiring often long-term treatment. While the selection of lamivudine resistance mutations is frequent, adefovir has a high genetic barrier. HIV infection negatively impacts on HBV disease, requiring these coinfected patients strategies aimed to manage both viruses.     

Current treatment indications and strategies in chronic hepatitis B virus infection

The optimal approach to the management of several marginal cases with chronic hepatitis B virus （HBV） infection is controversial. Serum HBV DNA and aminotransferase levels, and the degree of necroinflammation and fibrosis determine the therapeutic decisions. All patients with elevated aminotransferase （〉 twice the upper limit of normal） and serum HBV DNA above 20000 IU/mL should be treated. Liver biopsy is important for therapeutic decisions in cases with mild aminotransferase elevations and serum HBV DNA below 20000 IU/mL. Chronic HBV patients who do not receive treatment should be followed for life. There are seven agents licensed for chronic hepatitis B： standard and pegylated interferon-alpha, lamivudine, adefovir, entecavir, telbivudine and tenofovir. One-year courses with pegylated interferon-alpha induce sustained offtherapy remission in 30%-32% of patients with HBeAg- positive chronic hepatitis B and in a smaller proportion of patients with HBeAg-negative chronic hepatitis B. Oral antivirals achieve initial on-therapy responses in the majority of patients, but are intended as long-term therapies. Viral suppression has favourable effects on patients＇ outcome and modifies the natural course of the disease. Viral resistance, however, is the major drawback of long-term oral antiviral therapy. Lamivudine monotherapy is associated with the highest and entecavir monotherapy with the lowest resistance rate so far. There has been no resistance to tenofovir, but after only 18 mo of treatment to date. The optimal first-line anti-HBV therapy with the best long-term cost/benefit ratio remains unclear. If oral antiviral agents are used, compliance should always be ascertained and HBV DNA levels should be regularly tested.     

Treatment of chronic hepatitis B

Interferon (IFN) alpha, lamivudine, and adefovir are the three antiviral therapies currently approved for the treatment of chronic hepatitis B virus (HBV). Initiation of treatment is indicated in patients with abnormal liver enzymes and markers of active viral replication (ie, HBV DNA positive). Hepatitis B early antigen seroconversion rates are higher and treatment duration is shorter with IFN than with lamivudine or adefovir. However, treatment results in frequent side effects and many patients have contraindications to therapy. Lamivudine and adefovir are better tolerated, but have lower seroconversion rates after 12 months of treatment. Resistance develops in 20% of lamivudine patients after 12 months; adefovir resistance has not been identified to date. Individualization of therapy, based on factors such as patient comorbidities, response to prior therapies, and stage of disease (ie, presence of cirrhosis), is recommended. All patients over the age of 40 or with advanced liver disease should be continually screened for hepatocellular carcinoma with serum alphafetoprotein and abdominal imaging every 6 months.     

Adefovir rapidly suppresses hepatitis B in HBeAg-negative patients developing genotypic resistance to lamivudine

Progression of hepatitis B in patients with lamivudine-resistant strains is slowed down by adefovir dipivoxil (ADV). Whether the time point of ADV administration (genotypic vs. phenotypic resistance) influences the outcome of therapy is unknown. We compared the outcome of ADV therapy in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B patients with genotypic and phenotypic resistance to lamivudine. Ten milligrams of ADV was administered daily for 2 years to 46 HBeAg-negative patients at the time of phenotypic resistance (group A, >6 log(10) copies/mL of hepatitis B virus [HBV] DNA and high alanine aminotransferase [ALT] levels) and 28 patients at the time of genotypic resistance (group B, 3-6 log(10) copies/mL of HBV-DNA and normal ALT). HBV DNA was assessed every 2 months using Versant 3.0 assay, and lamivudine resistance was confirmed via INNO-LiPA assay in all patients. By month 3, HBV DNA tested negative in all patients from group B compared with only 20 (46%) in group A (P < .0001). The 2-year rates of virological response were 100% in the former patients and 78% in the latter ones (P < .0001). ALT levels remained persistently normal in all group B patients, whereas in group A patients they normalized at rates of 50% at month 6 (P < .0001), 72% at month 12 (P < .01), and 93% at month 24. None of the patients developed ADV resistance or ADV-related side effects. In conclusion, to optimize antiviral treatment in HBeAg-negative patients selecting resistant strains to lamivudine, ADV should be added to lamivudine as soon as genotypic resistance is detected.     

阿德福韦酯治疗慢性乙型肝炎65例观察

目的探讨阿德福韦酯单独或联合拉米夫定治疗慢性乙型肝炎的疗效。方法 12例HBeAg阳性患者给予阿德福韦酯,39例HBeAg阳性患者给予拉米夫定和阿德福韦酯,14例HBeAg阴性患者接受阿德福韦酯治疗。各组均观察24个月。结果联合治疗HBeAg阳性和阿德福韦酯治疗HBeAg阴性患者在治疗3个月、6个月、12个月和24个月时,血清HBV DNA水平均明显低于阿德福韦酯治疗HBeAg阳性患者;三组ALT复常率无显著性相差。结论阿德福韦酯联合拉米夫定初始治疗HBeAg阳性或阿德福韦酯治疗HBeAg阴性慢性乙型肝炎患者均能取得较好的疗效。