Combination chemotherapy for hepatitis B virus: the final solution?

Lamivudine/pegylated interferon alfa-2b sequential combination therapy compared with lamivudine monotherapy in HBeAg-negative chronic hepatitis B

BACKGROUND AND AIM

Monotherapy has been proven insufficient in achieving sustained control of chronic hepatitis B. We aimed to assess the efficacy of combined sequential administration of lamivudine and pegylated interferon alfa-2b in patients with hepatitis Be antigen (HBeAg)-negative chronic hepatitis B.

METHODS

Eighteen patients were given sequential combination treatment starting with 3 months of lamivudine monotherapy followed by 9 months of pegylated interferon alfa-2b (after a 3-month period of concomitant administration of the two drugs) and 24 patients received lamivudine monotherapy.

RESULTS

At the end of treatment, 88.9% of the patients who received sequential combination treatment and 70.8% of those who received lamivudine monotherapy had hepatitis B virus (HBV) DNA levels below 400 copies/mL (P = not significant). At the end of treatment, 72.2% of the patients who received sequential combination treatment and 70.8% of those who received lamivudine monotherapy achieved alanine aminotransferase normalization (P = not significant). After 12 months of follow up, 33.3% of the patients who received sequential combination treatment and 16.7% of those who received lamivudine monotherapy had HBV-DNA levels below 400 copies/mL (P = 0.4). After 12 months of follow up, 72.2% of the patients who received sequential combination treatment and 25.0% of those who received lamivudine monotherapy had normal alanine aminotransferase levels (P < 0.01). Twenty-five percent of the patients in the lamivudine monotherapy group had virological breakthrough compared to none in the sequential combination treatment group (P = 0.06).

CONCLUSIONS

Sequential combination treatment is able to improve sustained biochemical response rates and prevent the emergence of lamivudine-resistant mutants in patients with HBeAg-negative chronic hepatitis B.

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.

Drugs in development for hepatitis B

The management of chronic hepatitis B (CHB) has improved dramatically over the last decade with the development of new drugs such as lamivudine and adefovir dipivoxil, in addition to the now standard interferon (IFN)-alpha therapy. These new drugs can achieve a significant reduction or inhibit replication of hepatitis B virus (HBV) DNA during therapy. However, in the majority of patients, particularly in those who are hepatitis B e antigen (HBeAg)-negative, the sustained off-therapy suppression of HBV DNA is rare. For this reason, several new antiviral and immunomodulatory agents are currently being evaluated. Among the immunomodulatory agents, pegylated IFNalpha (peginterferon-alpha) has been shown to be more effective for HBeAg-positive CHB than either lamivudine or standard IFNalpha monotherapy, particularly in those patients infected by HBV genotypes A and B. The new antivirals entecavir, tenofovir disoproxil fumarate and telbivudine exhibit a more potent viral inhibitory effect than the currently approved drugs (IFNs, lamivudine and adefovir dipivoxil). However, the emergence of viral resistance has been witnessed and this could be one of the major limitations to the clinical use of these new drugs, particularly during prolonged therapy. In HBeAg-negative patients it is more and more common for oral antiviral therapy to be administered for prolonged periods, as the sustained off-therapy response rates of short-term therapy are very low. Different studies are currently evaluating combination therapy, using lamivudine with adefovir dipivoxil or peginterferon-alpha with lamivudine; the preliminary results show virological responses no better than those achieved by monotherapy. However, as combination therapy is associated with a low likelihood of developing HBV drug resistance, this could result in a higher virological response during prolonged therapy. In the near future the most realistic therapeutic option for the majority of patients with CHB will be long-term use of these new, more potent antiviral drugs, if they can achieve good safety profiles while maintaining low resistance rates at affordable costs.

Effectiveness of prophylactic Anti-HBV therapy in allogeneic hematopoietic stem cell transplantation with HBsAg positive donors

Use of hepatitis B surface antigen (HBsAg) positive donors for allogeneic hematopoietic stem cell transplantation (HSCT) causes serious hepatitis B virus (HBV)-related liver morbidity and mortality in the recipient. We compared the effectiveness of anti-HBV therapy in 29 recipients who underwent HSCT using HBsAg positive marrow (group I) against a historical control group of 25 patients who received HBsAg positive marrow without pre-HSCT prophylaxis (group II). Anti-HBV therapy consisted of lamivudine for HBsAg-positive donors and all recipients (n = 29) as well as HBV vaccination to all HBsAg-negative recipients (n = 10) before HSCT. After transplantation, HBV-related hepatitis was significantly higher in group II than group I recipients [12 of 25 recipients (48%) vs. 2 of 29 recipients (6.9%), p = 0.002] and in recipients whose donors had detectable serum HBV DNA by Digene Hybrid Capture II assay [8 of 14 recipients (57.1%) vs. 6 of 40 recipients (15.0%), p = 0.02]. Six recipients in group II and none in group I died of HBV-related hepatic failure (24.0% vs. 0%, p = 0.01). By multivariate Cox analysis, anti-HBV therapy effectively reduces post-HSCT HBV-related hepatitis (p = 0.01, adjusted hazards ratio 7.27, 95%CI 1.62-32.58). Our data support the use of prophylactic therapy in preventing HBV-related hepatitis after allogeneic HSCT from HBsAg-positive donor.

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.

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.

Management of chronic hepatitis B in treatment-experienced patients

Current monotherapy with interferon (IFN), lamivudine, or adefovir remains unsatisfactory for most patients with chronic hepatitis B infection. Prolonged treatment with lamivudine monotherapy is needed in most patients with chronic hepatitis B infection and leads to an increased risk of developing lamivudine resistance. Recent data suggest that lamivudine resistance occasionally can result in serious clinical sequelae. On the other hand, conventional IFN treatment is ineffective in up to 70% of chronic hepatitis B patients. Adefovir resistance, although less frequent than lamivudine resistance,also has been identified. With the introduction of new nucleoside/nucleotide analogs such as entacavir, clevudine, LFd4C,tenofovir, and immunomodulatory agents such as pegylated IFN, new treatment options, either alone or in combination, are being investigated to increase the response rate in treatment-naïve and treatment-experienced chronic hepatitis B patients.

Early detection of hepatitis B drug resistance: implications for patient management

Despite the availability of safe and effective prophylactic vaccines, hepatitis B viral disease has remained a tenacious scourge, ranking ninth globally among all causes of mortality (up to 1 million deaths annually). Approximately 6% of the global population--more than 350 million people--have failed to resolve viral infection and become chronic carriers, eventually placing between 15 and 25% of such individuals at risk for end-stage liver disease. Until recently, the immunomodulator interferon-alpha and especially the nucleoside analog lamivudine (Epivir) have been the treatments of choice for chronic hepatitis B viral infection. However, the inexorable development of drug resistance to lamivudine has been a major clinical impediment to the long-term use of such treatment. Herein, the current and future diagnostic methods for early detection of emerging drug resistance to the hepatitis B virus is reviewed. Given the recent approval of adefovir dipivoxil (Hepsera) and the possibility that other nucleoside and nucleotide analogs could soon become part of the hepatitis B virus therapeutic arsenal, the clinical ramifications for co-ordinated use of diagnostic tests together with new antihepadenaviral agents for optimal patient management is also discussed.

Review article: current management of chronic hepatitis B

Chronic hepatitis B can be diagnosed in patients with increased aminotransferases, hepatitis B virus viraemia and necroinflammation with fibrosis on liver biopsy. Although, ideally, all patients with chronic hepatitis B should be treated, therapeutic intervention is currently recommended for cases with a relatively satisfactory likelihood of response and/or advanced disease. A realistic therapeutic approach aims to sustain hepatitis B e antigen (HBeAg) loss and hepatitis B e antibody (anti-HBe) seroconversion in HBeAg-positive chronic hepatitis B and to sustain biochemical and virological remission in HBeAg-negative chronic hepatitis B. Currently, three drugs are licensed for chronic hepatitis B: interferon-alpha, lamivudine and adefovir dipivoxil. In patients with HBeAg-positive chronic hepatitis B, all of these drugs achieve HBeAg loss (24-33%) and anti-HBe seroconversion (12-30%) rates significantly superior to those observed in untreated placebo controls. In patients with HBeAg-negative chronic hepatitis B, the sustained off-therapy response rate is 20-25% after a > or =12-month course of interferon-alpha and minimal (<10%), if any, after a 12-month course of lamivudine or adefovir. Long-term lamivudine induces an initial response in 70-90% of patients, but only 30-40% of patients remain in remission after the third year due to progressively increasing viral resistance. Long-term adefovir achieves a response in approximately 70% of patients at 12 months, which is maintained at 24 months with rare (<2%) drug resistance. Adefovir is also effective against lamivudine-resistant strains. Many other anti-viral agents, immunomodulatory approaches and combination therapies are currently being evaluated in chronic hepatitis B.

Hepatitis B reactivation in patients positive for hepatitis B surface antigen undergoing autologous hematopoietic cell transplantation

Hepatitis due to reactivation of hepatitis B virus is an important cause of liver-related morbidity and mortality in hepatitis B surface antigen (HBsAg) positive patients undergoing autologous hematopoeitic cell transplantation. With the recent introduction of sensitive serum HBV DNA quantitation assay, the diagnosis of hepatitis B reactivation can now be made more reliably. As these hepatitis are driven by the host immune response to a surge of hepatitis B viral load, the availability of effective nucleoside analogues which can inhibit hepatitis B viral replication has opened up new approaches to this previously untreatable condition. Up till now, two such nucleoside analogues, lamivudine and adefovir dipivoxil, have been approved for the treatment of chronic hepatitis B infection. However, further studies are needed to determine which nucleoside analogues should be chosen in this transplant setting. Due to the high dose chemotherapy generally needed in autologous hematopoeitic cell transplantation, there is a high risk of post-transplant hepatitis B reactivation. Hence, all HBsAg positive patients undergoing autologous hematopoeitic cell transplantation should preferably be treated pre-emptively with nucleoside analogous. An alternative approach is to defer treatment with nucleoside analogous until there is evidence of hepatitis B virological reactivation. However, the latter approach would need the patient's hepatitis B viral load be monitored at a very close interval and might not be cost-effective.

Resistance to adefovir dipivoxil therapy associated with the selection of a novel mutation in the HBV polymerase

BACKGROUND & AIMS

Adefovir dipivoxil effectively inhibits both hepatitis B virus (HBV) replication and disease activity in patients with chronic hepatitis B. Resistance to treatment was not observed in 2 recent large placebo-controlled 48-week studies with this drug. The aim of this study was to characterize adefovir resistance in a patient who developed clinical and virologic evidence of breakthrough during a 96-week course of treatment.

METHODS

HBV DNA was PCR amplified and sequenced. Phenotypic studies used patient-derived HBV as well as specific mutations created by site-directed mutagenesis of a HBV/baculovirus recombinant.

RESULTS

Following the commencement of treatment with adefovir dipivoxil, the patient initially responded with a 2.4 log(10) decrease in serum HBV DNA and normalization of alanine aminotransaminase levels by week 16. During the second year of treatment, however, serum HBV DNA rose progressively, eventually returning to near-pretreatment levels. This increase in viral replication was associated with a marked increase in alanine aminotransferase and mild changes in bilirubin, albumin, and prothrombin time. Comparison of pretreatment and posttreatment HBV DNA by polymerase chain reaction sequencing identified a novel asparagine to threonine mutation at residue rt236 in domain D of the HBV polymerase. In vitro testing of a laboratory strain encoding the rtN236T mutation and testing of patient-derived virus confirmed that the rtN236T substitution caused a marked reduction in susceptibility to adefovir.

CONCLUSIONS

The development of this novel mutation in the HBV polymerase confers resistance to adefovir dipivoxil. The patient responded to subsequent lamivudine therapy, achieving normalization of alanine aminotransferase and a significant decrease in serum HBV DNA.

Occult HBV infection and YMDD variants in hemodialysis patients with chronic HCV infection

BACKGROUND/AIMS

End-stage renal disease patients on chronic hemodialysis are at risk for both hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. Although the prevalence is unknown in hemodialysis patients, occult HBV infection is frequent in subjects with chronic HCV infection. We aimed to investigate (1) the prevalence and clinical impact of occult HBV infection in hemodialysis patients with chronic HCV infection, and (2) the frequency of YMDD variants (tyrosine-methionine-aspartate-aspartate amino acid motif of HBV polymerase) in this setting.

METHODS

Thirty-three anti-HCV and HCV-RNA-positive, HBsAg-negative hemodialysis patients (mean age 36.9+/-10.4 years, 22 male) were admitted to this study. HBV-DNA (Innogenetics kit) and HCV-RNA (Cobas Amplicor HCV kit) were investigated by polymerase chain reaction technique (PCR). YMDD mutation was studied in all HBV-DNA-positive patients by the BOOM method.

RESULTS

HBV-DNA was detected in 12 of 33 patients (36.4%) by PCR. Their mean age was 33.0+/-9.0 years. Age, dialysis period (years) and biochemical parameters were not significantly different in patients with and without occult HBV infection. YMDD variants were identified in six of 12 (50%) patients with occult HBV infection.

CONCLUSIONS

Occult HBV infection is frequent in hemodialysis patients with chronic HCV infection. YMDD variants are common in this setting.

Hepatitis B treatment: rational combination chemotherapy based on viral kinetic and animal model studies

Hepatitis B virus (HBV) causes a generally non-cytopathic infection in the liver. Even though HBV is a DNA virus, it replicates via reverse transcription which is coordinated within the viral nucleocapsid by the virus-specific polymerase. The major transcriptional template is the viral mimichromosome from which the viral DNA exists as a covalently closed circular (ccc) molcule. The virus infects hepatocytes but can also be found in non-hepatocyte reservoirs such as bile-duct epithelium, mesangial cells of the kidney, pancreatic islet cells and lymphoid cells. When patients infected with HBV are treated with either interferon alpha or lamivudine, responses are variable and unpredictable. Sophisticated mathematical models analysing the dynamics of viral clearance during antiviral therapy have recently been applied to chronic hepatitis B. Typically complex profiles, rather than the usual biphasic responses seen with other diseases have been observed, indicating that antiviral efficacy requires substantila improvement. This may be achieved with combination chemotherapy. However, chronic hepatitis B is a complex and heterogeneous disease entity, and the challenge for the future is to define measurable end-points of treatment and address key virological issues such as the role of cccDNA and extra-hepatocyte replication in treatment failure. Clearly, new therapies and effective combination therapy protocols are urgently required in order to improve the present poor response rates in patients undergoing treatment.

Preemptive use of lamivudine reduces hepatitis B exacerbation after allogeneic hematopoietic cell transplantation

Exacerbation of hepatitis B virus (HBV) is a serious cause of morbidity and mortality in hepatitis B surface antigen (HBsAg)-positive patients undergoing transplantation. Our aim was to evaluate the effectiveness of lamivudine to prevent hepatitis due to exacerbation of HBV in HBsAg-positive patients treated with allogeneic hematopoietic cell transplantation. We studied 20 consecutive HBsAg-positive recipients of allogeneic hematopoietic cell transplantation who received lamivudine 100 mg daily starting one week before transplantation until week 52 after transplantation (group 1). Serial serum alanine aminotransferase and HBV DNA levels were measured before and after transplantation at 4- to 8-week intervals for the first year and then 4- to 12-week intervals. Their virologic and clinical outcomes were compared with 20 case-matched recipients who did not receive any antiviral therapy to HBV (anti-HBV) before and after hematopoietic cell transplantation (group 2). After transplantation, 9 patients (45%) in group 2 and one patient (5%) in group 1 had hepatitis due to exacerbation of HBV (P <.008), with 3 hepatic failures in group 2 and none in group 1. The one-year actuarial probability of survival without hepatitis due to exacerbation of HBV was higher in group 1 than group 2 (94.1% vs. 54.3%, P =.002). By multivariate Cox analysis, preemptive use of lamivudine effectively reduced hepatitis due to exacerbation of HBV (adjusted hazards ratio, 0.09; P =.021). In conclusion, preemptive lamivudine reduced HBV exacerbation. The use of lamivudine with other immunosuppressive regimens to prevent exacerbation of HBV should be further explored.

Efficacy of granulocyte-macrophage colony-stimulating factor or lamivudine combination with recombinant interferon in non-responders to interferon in hepatitis B virus-related chronic liver disease patients

BACKGROUND AND AIMS

Non-response to interferon (IFN) monotherapy is a major therapeutic problem in the management of chronic hepatitis B infection. The efficacy of combination therapy to enhance the immunomodulatory effect of IFN by combining granulocyte-macrophage colony-stimulating factor (GMCSF) or decreasing viral load by adding an antiviral agent such as lamivudine was evaluated prospectively.

METHODS

Twenty-four patients with chronic hepatitis B who were non-responders to previous IFN therapy were randomized to receive an IFN and GMCSF (group A, n = 10) or IFN and lamivudine (group B, n = 14) combination for 6 months. The end-of-treatment response was assessed by hepatitis B virus (HBV)-DNA and hepatitis B e antigen (HBeAg) determination.

RESULTS

All patients successfully completed both the treatment schedules. The mean age, alanine aminotransferase (ALT) levels, liver histology, HBV-DNA levels and distribution of HBV genotypes were comparable between the two groups. At the end of treatment there was a significant decrease in mean ALT levels. The HBV-DNA and HBeAg loss was seen in six of 10 (60%) patients in group A and in seven of 14 (50%) patients in group B. During a mean follow-up of 15 +/- 3 months, two of six (33%) patients in group A and three of seven (43%) patients in group B relapsed with HBV-DNA and HBeAg positivity, which meant an overall sustained response of 40% and 28%, respectively. None of the factors such as HBV viral load, ALT levels or liver histology could predict the non-response to combination therapy or occurrence of relapse. There was a trend in patients with genotype A compared with genotype D towards non-response to therapy, although the difference was not significant.

CONCLUSIONS

The combination of IFN plus GMCSF or lamivudine was effective in non-responders to IFN monotherapy. Larger studies using such combination therapies would be helpful in improving treatment strategies for chronic hepatitis B.

Thymosin-alpha1 and famciclovir combination therapy activates T-cell response in patients with chronic hepatitis B virus infection in immune-tolerant phase

We examined whether combination therapy with thymosin-alpha1 and famciclovir would induce hepatitis B e antigen seroconversion in patients with chronic hepatitis B infection in the immune-tolerant phase without inducing significant hepatic necro-inflammation. We studied 32 hepatitis B e antigen positive patients in the immune-tolerant phase of infection, treated with 26-weeks combination therapy of famciclovir and thymosin-alpha1 (group 1). Thirty-two patients who received 26-weeks famciclovir monotherapy (group 2) and another 32 patients who received no treatment (group 3), served as controls. Peripheral blood mononuclear cell proliferation and cytokine secretion in response to recombinant HBV core and surface antigen and serial serum HBV-DNA, were assayed. No significant difference in adverse events were observed among the three groups. By week 26, the median reduction in group 1 (0.94 log10 copies/mL) was greater than group 2 (0.70 log10 copies/mL, P < 0.001). Five (15.6%) patients in group 1 at 52 weeks (median range 13-78 weeks) and none in group 2 or 3 experienced hepatitis B e antigen seroconversion (P = 0.053). Sustained serological clearance of hepatitis B e antigen was associated with activation of CD4 positive HBV-specific T-cell reactivity and were of T-helper 1. Hence combination therapy with immunomodulatory agents and nucleoside analogues should be explored.

High hepatitis B virus (HBV) DNA viral load as the most important risk factor for HBV reactivation in patients positive for HBV surface antigen undergoing autologous hematopoietic cell transplantation

The risk factors for hepatitis due to hepatitis B virus (HBV) reactivation in patients positive for hepatitis B surface antigen (HBsAg) treated with autologous hematopoietic cell transplantation (HCT) are unknown. We evaluated 137 consecutive patients (23 positive for HBsAg, 37 positive for hepatitis B surface antibody, and 77 negative for HBV) who underwent HCT. Serial serum ALT were measured before transplant and after transplant at 1 to 4 weekly intervals for the first year and then at 2 to 12 weekly intervals thereafter. Before HCT, basic core promoter (T(1762)/A(1764)) and precore (A(1896)) HBV variants were determined in HBsAg-positive and HBV DNA-positive (by polymerase chain reaction assay) patients by direct sequencing and serum HBV DNA quantitation using the Digene Hybrid Capture II assay. Cox proportional hazards analysis was used to assess the association between pretransplantation HBV virologic and host factors and occurrence of hepatitis due to HBV reactivation. After HCT, hepatitis due to HBV reactivation was more common in HBsAg-positive patients than in HBsAg-negative patients (hazard ratio, 33.3; 95% confidence interval [CI], 7.35-142.86; P <.0001). HBsAg-positive patients with detectable serum HBV DNA before HCT (on Digene assay) had a significantly higher risk of hepatitis due to HBV reactivation than HBsAg-positive patients with no detectable serum HBV DNA (adjusted hazard ratio, 9.35; 95% CI, 1.65-52.6; P =.012). Thus, we found that hepatitis due to HBV reactivation is common in HBsAg-positive patients undergoing autologous HCT. A high HBV DNA level (>10(5) copies/mL) was the most important risk factor for HBV reactivation, and its lowering by administration of nucleoside analogues before transplantation should be considered.

How will we use the new antiviral agents for hepatitis B?

There are two licensed drugs for chronic hepatitis B virus (HBV), interferon alfa and lamivudine, with similar efficacy rates. Lamivudine is less expensive and better tolerated than interferon alfa and is the drug of choice for patients with decompensated cirrhosis and recurrent HBV infection after liver transplantation. The major problem with lamivudine monotherapy has been the emergence of drug-resistant HBV polymerase (YMDD) mutants. Thus, long-term use of lamivudine in other settings remains somewhat controversial. Alternative nucleoside analogues that are active against both wild-type and YMDD-mutant HBV are currently being tested. It is hoped that a combination of one or more of these agents with lamivudine will not only prove more effective than lamivudine alone but also decrease the rate of lamivudine resistance. Preliminary studies suggest that the combination of interferon and lamivudine is associated with an enhanced rate of virologic response when compared with either agent alone. From a theoretical perspective, the combination of interferon with one or more nucleoside analogues may be the most effective way to treat HBV infection in many clinical situations.

Treatment of chronic hepatitis B

This review updates the treatment of chronic hepatitis B infection. Complete eradication of hepatitis B virus (HBV) is not possible, so the efficacy of treatment has to be assessed by whether it can limit long-term cirrhosis-related complications. We discuss two major groups of treatments--immunomodulators (interferon alfa, thymosin alpha1, therapeutic vaccines) and nucleoside analogues (lamivudine, adefovir, entecavir, emtricitabine, beta-L-2'-deoxythymidine). To date, interferon alfa and lamivudine are the only two agents approved for chronic hepatitis B. Interferon alfa achieves a short-term outcome of around 20-30% loss of HBeAg. The efficacy is lower in Chinese patients, who are immunotolerant to HBV because of acquisition of the disease during early childhood, than in white patients. This difference is further confirmed on long-term follow-up. Interferon alfa does not affect the development of cirrhosis-related complications in Chinese patients, whereas in white patients, the frequency of long-term complications is reduced if interferon alfa is successful in inducing loss of HBeAg. Lamivudine profoundly suppresses viral replication and achieves an HBeAg seroconversion rate similar to that of interferon alfa. It is equally effective in Chinese and white patients because the main antiviral mechanism is through inhibition of reverse transcription of HBV during viral replication. However, long-term lamivudine therapy is associated with emergence of HBV variants, YMDD variants. Newer nucleoside analogues are being extensively investigated by studies in vivo and in vitro. Combination therapy with two or three nucleoside analogues or immunomodulators plus nucleoside analogues will be the future direction of treatment of chronic hepatitis B.

Therapeutic advances in the management of hepatitis B and hepatitis C

Until recently, interferon monotherapy has been the only available therapeutic option for patients with chronic hepatitis B and hepatitis C. Lamivudine has emerged as another effective first-line therapy for chronic hepatitis B as well as a beneficial treatment option for patients with decompensated hepatitis B cirrhosis. Viral resistance with long-term lamivudine therapy remains a major concern but new data continue to show benefits despite the development of YMDD mutations. Combination therapy with ribavirin and pegylated interferon-alpha has revolutionized the treatment of chronic hepatitis C. The rate of sustained virological response can now be expected to be as high as nearly 50% for genotype 1 and 80% for non-1 genotypes of hepatitis C.

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.

Resistance of hepatitis B virus to antiviral drugs: current aspects and directions for future investigation

Despite the existence of vaccines, chronic hepatitis B virus (HBV) infection remains a major health problem worldwide. Interferon therapy successfully controls infection in only a small percentage of chronically infected individuals. The recent approval of the nucleoside analogue lamivudine for the treatment of chronic HBV infection has ushered in a new era of antiviral therapy. While lamivudine is highly effective at controlling viral infection short-term, prolonged therapy has been associated with an increasing incidence of viral resistance. Thus, it appears that lamivudine alone will not be sufficient to control chronic viral infection in the majority of individuals. In addition to lamivudine, several new nucleoside and nucleotide analogues that show promising antihepadnaviral activity are in various stages of development. Lamivudine resistance has been found to confer cross-resistance to some of these compounds and it is likely that resistance to newer antivirals may also develop during prolonged use. Drug resistance therefore poses a major threat to nucleoside analogue-based therapies for chronic HBV infection. Fortunately, combination chemotherapy (antiviral therapy with two or more agents) can minimize the chance that resistance will develop and can be expected to achieve sustained reductions in viral load, provided that suitable combinations of agents are chosen. Here we review the basis of drug resistance in HBV, with emphasis on aspects that are likely to affect drug choice in future.

Chinese medicinal herbs for chronic hepatitis B

BACKGROUND

Hepatitis B virus infection is a serious health problem worldwide. Traditional Chinese medicinal herbs have been widely used to treat chronic liver diseases, and many controlled trials have been done to investigate their efficacy.

OBJECTIVES

To assess the efficacy and safety of traditional Chinese medicinal herbs for chronic hepatitis B infection.

SEARCH STRATEGY

Searches were applied to the following electronic databases: the CHBG Trials Register, the Cochrane Complementary Medicine Field Trials Register, the Cochrane Library, MEDLINE, EMBASE and BIOSIS. Five Chinese journals and conference proceedings were handsearched. No language restriction was used.

SELECTION CRITERIA

Randomised or quasi-randomised trials with at least three months follow-up. Trials of Chinese medicinal herbs (single or compound) compared with placebo, no intervention, general non-specific treatment or interferon treatment were included. Trials of Chinese medicinal herbs plus interferon versus interferon alone were also included. Trials could be double-blind, single-blind or not blinded.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two reviewers. The methodological quality of trials was evaluated using the Jadad-scale plus allocation concealment. Intention-to-treat analyses were performed.

MAIN RESULTS

Nine randomised trials, including 936 patients, met the inclusion criteria. Methodological quality was considered adequate in only one trial. There was a significant funnel plot asymmetry (regression coefficient=3.37, standard error 1.40, P=0.047). Ten different medicinal herbs were tested in the nine trials. Compared to non-specific treatment or placebo, Fuzheng Jiedu Tang (compound of herbs) showed significantly positive effects on clearance of serum HBsAg, HBeAg, and HBV DNA; Polyporus umbellatus polysaccharide on serum HBeAg and HBV DNA; Phyllanthus amarus on serum HBeAg. Phyllanthus compound and kurorinone showed no significant effect on clearance of serum HBeAg and HBV DNA and on alanine aminotransferase normalisation compared to interferon treatment. There were no significant effects of the other examined herbs.

REVIEWER'S CONCLUSIONS

Some Chinese medicinal herbs may work in chronic hepatitis B. However, the evidence is too weak to recommend any single herb. Rigorously designed, randomised, double-blind, placebo-controlled trials are required.