Antiviral therapy of chronic hepatitis B: past, present, and future

Ultra-Long-term Follow-up of Interferon Alfa Treatment for HBeAg-Positive Chronic Hepatitis B Virus Infection

BACKGROUND AND AIMS

Interferon-alpha (IFN-α) treatment for chronic hepatitis B (CHB) virus infection is finite and leads to relatively higher functional cure rates (HBsAg loss) than nucleo(s)tide analogue (NA) therapy. Effects of pegylated (PEG)/conventional IFN-α treatment on clinical outcomes were evaluated in an ultra-long-term follow-up of CHB patients.

METHODS

HBeAg-positive patients treated with (PEG)IFN-α at a tertiary referral centre between 1977-2014 were included. We reviewed medical charts and consulted the municipal registry for patient information. Patients were invited for a single visit at the outpatient clinic in the case of missing follow-up data. The endpoints included serum HBeAg/HBsAg loss and incidence of clinical events, using life table methods and person-years to analyze the incidence of events. Patients were censored upon retreatment.

RESULTS

The study cohort included 267 patients, 67% male, 58% Caucasian, with a median age of 32 years. The median follow-up duration was 11.5 years. The 5 and 10-year cumulative incidence of HBsAg loss were 14% and 32%, respectively. Baseline factors associated with a higher rate of HBsAg loss were male sex, Caucasian race, genotype A, age ≥40 years, and cirrhosis. HBsAg loss rates did not differ significantly between those who received short-term (≤24 weeks) vs long-term (>24 weeks) therapy. Both HBeAg and HBsAg loss were significantly associated with improved clinical outcomes. Early response (HBeAg loss) was associated with more HBsAg loss and better patient outcomes.

CONCLUSIONS

During long-term follow-up, high rates of HBsAg loss were observed from a single (PEG)IFN-α course. Its persistent effects suggest that a role for IFN-α remains, potentially in novel combination therapies in search of a functional cure.

Chronic hepatitis B infection and risk of preterm labor: a meta-analysis of observational studies

Many epidemiological studies have found a positive association between chronic hepatitis B virus (CHB) infection and the risk of preterm labor, but the magnitude of this association varies and independent studies have reported conflicting findings. We performed a meta-analysis to ascertain the relationship between CHB infection and preterm labor. The PubMed and Embase databases were searched up to May 1st, 2014, for relevant observational studies on an association between CHB infection and the risk of preterm labor. Data were extracted and analyzed independently by two authors. The meta-analysis was performed using Stata version 10.0 software. Six observational case-control studies and 4 cohort studies, involving 6781 women with preterm labor, were identified. Based on a random-effects meta-analysis, no association between CHB infection and preterm labor was identified (odds ratio=1.12, 95% confidence interval CI, 0.94-1.33). Our meta-analysis suggested that CHB infection is not associated with an increased risk of preterm labor.

Evaluation of single and combination therapies with tenofovir disoproxil fumarate and emtricitabine in vitro and in a robust mouse model supporting high levels of hepatitis B virus replication

Next-generation therapies for chronic hepatitis B virus (HBV) infection will involve combinations of established and/or experimental drugs. The current study investigated the in vitro and in vivo efficacy of tenofovir disoproxil fumarate (TDF) and/or emtricitabine [(-)-FTC] alone and in combination therapy for HBV infection utilizing the HepAD38 system (human hepatoblastoma cells transfected with HBV). Cellular pharmacology studies demonstrated increased levels of (-)-FTC triphosphate with coincubation of increasing concentrations of TDF, while (-)-FTC had no effect on intracellular tenofovir (TFV) diphosphate levels. Quantification of extracellular HBV by real-time PCR from hepatocytes demonstrated the anti-HBV activity with TDF, (-)-FTC, and their combination. Combination of (-)-FTC with TDF or TFV (ratio, 1:1) had a weighted average combination index of 0.7 for both combination sets, indicating synergistic antiviral effects. No cytotoxic effects were observed with any regimens. Using an in vivo murine model which develops robust HBV viremia in nude mice subcutaneously injected with HepAD38 cells, TDF (33 to 300 mg/kg of body weight/day) suppressed virus replication for up to 10 days posttreatment. At 300 mg/kg/day, (-)-FTC strongly suppressed virus titers to up to 14 days posttreatment. Combination therapy (33 mg/kg/day each drug) sustained suppression of virus titer/ml serum (<1 log(10) unit from pretreatment levels) at 14 days posttreatment, while single-drug treatments yielded virus titers 1.5 to 2 log units above the initial virus titers. There was no difference in mean alanine aminotransferase values or mean wet tumor weights for any of the groups, suggesting a lack of drug toxicity. TDF-(-)-FTC combination therapy provides more effective HBV suppression than therapy with each drug alone.

Factors influencing clinical course and histological findings in children with chronic hepatitis B

INTRODUCTION

Although the clinical course of chronic hepatitis B (CHB) is relatively mild in a majority of children, a certain proportion of patients develops chronic liver disease that finally results in serious liver injury. Reports regarding clinical outcome of infection are scarce.

OBJECTIVE

The aim of this study was to assess inflammatory activity, fibrosis, and their correlation to clinical data in children with CHB before antiviral treatment.

MATERIALS AND METHODS

The study included 200 children, aged 1.5-18 years (mean 7.49+/-4.01 years), with CHB hospitalized before liver biopsy between 1992 and 2003. History and clinical data were analyzed. Histopathological assessment was based on the modified Knodell system. Statistical analysis was performed, and results with P<0.05 were considered significant.

RESULTS

Necroinflammatory activity was found to be mild in 115 children and moderate in 44. Ninety-three children had minimal fibrosis (S1), 62 children - S2, and the remaining 8 - S3-S4. Alanine aminotransferase (ALT) activity was proportional to staging (Kruskall-Wallis test H=10.84, P=0.028) and was significantly higher in the children with staging >or=S2, P=0.0008. Spontaneous hepatitis B early antigen seroconversion occurred in 30/200 children (15%) and was related to the shorter length of infection, P=0.008.

CONCLUSION

Intensity of liver injury in children with CHB varies from minimal to marked necroinflammatory activity and fibrosis varies from none to advanced. Progression of liver fibrosis seems to be proportional to the age at infection. ALT activity appears to be higher in the children with significant (S2-S4) fibrosis. Spontaneous hepatitis B early antigen seroconversion is apparently related to the shorter length of infection and higher ALT activity.

Development of a novel mouse model to evaluate drug candidates against hepatitis B virus

Woodchuck hepatitis virus (WHV)-infected woodchucks have been used for preclinical development of drugs against hepatitis B virus (HBV). However, there is no simple in vivo model to evaluate small amounts of compounds against HBV. To develop such a model, HepAD38 cells, in which HBV replication is regulated by tetracycline (tet), were grown as subcutaneous tumours in nude mice. Mice developing viraemia were then left untreated or given tet in the drinking water. In some of the mice given tet, it was removed and the mice were injected intraperitoneally with phosphate buffer saline (PBS), lamivudine (3TC), clevudine (CLV) or tenofovir dipivoxil fumarate (TDF). Virus DNA titres were measured by real-time PCR during and after drug treatment. In water-fed and PBS-injected mice, virus titres reached approximately 10(9) copies/ml serum within 35 days of HepAD38 injection, whereas in tet-treated mice, virus titres remained at 10(4)-10(5) copies/ml. HBV DNA levels were suppressed by 3TC, TDF and CLV, with the latter two drugs showing more sustained virus suppression compared with 3TC. Combination therapy with CLV plus TDF was much more effective than either drug alone in suppressing virus titre for at least 3 weeks after the end of treatment. There was no demonstrable toxicity to HepAD38 cells in drug-treated mice. Hence, a robust tet-controlled system for HBV replication in vivo was demonstrated, validated with monotherapies against HBV and shown to be useful in assessing combination therapy. This system will be useful for preclinical assessment of small amounts of single or multiple compounds against HBV in vivo.

Acute flares in chronic hepatitis B: the natural and unnatural history of an immunologically mediated liver disease

Acute flares in chronic hepatitis B are common and may be caused by a number of identifiable and potentially treatable factors. The common link for many of these exacerbation episodes is a change in the immunologic response to hepatitis B virus (HBV), and this may have no identifiable cause or be triggered by an increase in viral replication or genotypic change. It is important to keep in mind the clinical situations in which patients are at increased risk of reactivated infection and secondary exacerbations. Reactivation is frequently induced by medical treatments such as cancer chemotherapy, antirejection drugs used in organ transplantation, and corticosteroids. The immunologic flares that often result from sudden withdrawal of these medications can be life-threatening unless recognized and treated promptly with antivirals, and there is increasing experience that preemptive antiviral treatment can diminish their occurrence and improve the outcome. The experience with lamivudine and other nucleoside analogues has increased our understanding of the molecular events behind hepatitis flares that occur when chronic hepatitis B is treated with drugs that potently inhibit HBV DNA polymerase. However, not all flares are explainable by events related to HBV infection alone. Depending on the population studied, as many as 20%-30% of flares may be caused by infection with other hepatotropic viruses, and this situation may inhibit HBV replication. Proper understanding of the etiology and effective treatment of acute flares in chronic hepatitis B requires an appreciation of high-risk clinical situations, assessment of HBV replication status, and testing for other viruses when appropriate.

Review: Present and future directions in the treatment of chronic hepatitis B infection

The last decade has witnessed substantial progress in the development of chemotherapeutic agents for chronic hepatitis B. However, the only currently licensed treatment in Australia, interferon-alpha, has low initial response rates and the adverse effects are often unacceptable. Of the newer agents in the class of nucleoside analogues, famciclovir and lamivudine are in phase III clinical trials with encouraging preliminary results, while other agents, such as bis-POM PMEA (Adefovir), are at phase I/II development. Future approaches to therapy will be governed by an understanding of the effects of nucleoside analogues on the natural history of the disease as well as on the hepatitis B virus hepatocyte interaction. Combination antiviral therapy should theoretically offer improved response rates, decrease the development of viral resistance, and provide the greatest reduction in viral load, but it has not yet been widely examined in the clinical setting. In this article, we review the currently available strategies, discuss potential problem areas, and speculate on promising approaches with combination chemotherapy and the features of agents soon to be trialed.

Long-term follow-up of HBeAg-positive patients treated with interferon alfa for chronic hepatitis B

BACKGROUND

In patients with chronic hepatitis B, treatment with interferon alfa and the consequent loss of hepatitis B e antigen (HBeAg) from the blood leads to a reduction in inflammatory activity, but the clinical benefits of this treatment have not been established. We evaluated whether HBeAg seroconversion induced by interferon alfa improves clinical outcome.

METHODS

We studied prospectively a cohort of 103 patients treated with interferon alfa for chronic hepatitis B; the mean (+/- SD) follow-up was 50.0 +/- 19.8 months. Fifty-three untreated patients served as controls.

RESULTS

After treatment with interferon alfa, 53 of 103 patients no longer had detectable HBeAg or hepatitis B virus DNA, although only 10 patients became seronegative for hepatitis B surface antigen (HBsAg) (Kaplan-Meier estimates of cumulative clearance rates at five years, 56.0 percent for HBeAg and 11.6 percent for HBsAg). Of the 53 untreated patients, only 7 spontaneously eliminated HBeAg (28.1 percent at five years), and all remained positive for HBsAg (p < 0.001 for the Comparison with the treated patients, by the proportional-hazards model). During follow-up, 6 of the 103 treated patients died of liver failure, and 2 needed liver transplantation, all 8 were persistently positive for HBeAg. In another eight treated patients, complications of cirrhosis developed; all but one of these patients remained positive for HBeAg. Overall survival and survival without clinical complications were significantly longer in patients who were seronegative for HBeAg after therapy with interferon alfa than in those who remained seropositive (P = 0.004 and P = 0.018, respectively). In a regression analysis, clearance of HBeAg was the strongest predictor of survival. Of the 53 untreated patients, 13 had severe complications (including 4 deaths and 1 need for liver transplantation); all 13 continued to be HBeAg-positive.

CONCLUSIONS

In patients with chronic hepatitis B infection, the clearance of HBeAg after treatment with interferon alfa is associated with improved clinical outcomes.

Recent results in the treatment of chronic B virus hepatitis

Of the drugs evaluated to date for the therapy of chronic hepatitis B, only alpha-interferons have gained wide acceptance as single-agent therapy. In HBeAg-positive carriers, treatment must be carried out for 4-6 months on an alternate-day basis and dosage should be not less than 5 million U/m2 of body surface. Oriental patients, children, immunodeficient and highly viremic patients are less likely to respond. Patients given combination therapy (with steroids, antivirals, stimulators of the immune system) do not appear to benefit from the association in comparison with treatment with interferon alone. In most patients (60-80%) with atypical chronic type B infections (anti-HBe-positive, HBV-DNA-positive, intrahepatic HBcAg), HBV-DNA becomes negative and transaminases normalize during interferon treatment; however, many (80%) experience a relapse of viremia and disease during follow-up. Side effects are usually minor (flu-like symptoms), but in a minority of patients, major adverse events have also been reported. alpha-Interferon is effective in inhibiting viral replication in a significant number of patients with chronic type B hepatitis, but new therapeutic regimens and a better selection of patients are needed in order to induce persistent remissions and reduce the cost/benefit ratio.

Sustained elimination of hepatitis B virus from serum induced in a patient with chronic hepatitis B and advanced human immunodeficiency virus infection

A 48-year-old male patient was admitted with acquired immunodeficiency syndrome (stage III, Centers for Disease Control 1993) and viremic hepatitis B. Blood CD4 count was 15/microliters. Discontinuation of prednisolone, previously prescribed by the patient's family practitioner because of elevated liver enzymes, resulted in severe hepatitis (alanine aminotransferase > 300U/l). Administration of interferon-alpha (9 x 10(6) U s.c. 3 x weekly) was initiated. Serum markers of viral replication disappeared, and aminotransferase levels returned to normal within a few weeks. The patient's serum was found negative for HBsAg after 3 months. Immunohistochemical analysis of liver biopsies before and during interferon therapy showed disappearance of all hepatitis B virus antigens and a marked reduction in inflammatory activity. Hepatitis B virus seroconversion remained stable until the patient died from the syndrome 2 years later. This case shows that in spite of severe HIV-associated immune deficiency with CD4 counts constantly below 100/microliters, interferon-alpha can lead to sustained serological and histological improvement of viremic hepatitis B. Previous administration and discontinuation of cortisone may have helped to reach this effect.

Viral hepatitis in children with renal disease

Specific and sensitive diagnostic tests are now available to identify type A, B, C, D and E hepatitis. Hepatitis A and E which cause only acute, very rarely fulminant, hepatitis are spread largely by the faecal-oral route, having a brief viraemic phase. Hepatitis B, C and D which are transmitted parenterally and via secretions are often associated with chronic viraemia. Patients with chronic renal disease are at particular risk. Impaired immunity due to disease or drugs increases the propensity to develop a chronic carrier state which may progress to cirrhosis and hepatocellular carcinoma. Limited reports indicate that hepatitis C infection may cause cirrhosis more rapidly than hepatitis B. The emergence of mutants to both hepatitis B and C is a cause for concern. Treatment with interferon is of limited efficacy. Screening of blood products for viral markers and prudent handling of potentially infected materials to avoid contamination of damaged skin or mucous membrane are the best strategies to prevent infection. Hepatitis B vaccination of all newborns, young adolescents and those at risk is the most effective means of reducing the carrier frequency.

Prospectives on the treatment of chronic hepatitis B and chronic hepatitis C with thymic peptides and antiviral agents

At the present time, interferon is considered the only effective therapeutic approach in the treatment of both chronic hepatitis B and chronic hepatitis C. It is clear that the disappointing response rates in both chronic hepatitis B and C place added emphasis on efforts to identify alternative forms of therapy. In addition to the development of other antiviral agents including the nucleoside analogs which might prove more effective and have fewer associated side-effects, other agents currently under investigation include thymic peptides such as thymosin alpha 1. In the future, the therapeutic approach to the treatment of chronic hepatitis B and C may consist of combination therapy using perhaps an immune modulator and an antiviral agent or, several antiviral drugs. Alternatively, there is indication that cellular targeting systems with delivery of the toxic material to the specific cell containing the virus may be more effective, while minimizing side-effects. Finally, there are agents such as ursodeoxycholic acid which perhaps, makes bile less toxic and can be used as adjunctive therapy with improvement in liver chemistry values. The treatment of chronic hepatitis B and chronic hepatitis C has shifted in emphasis form the concept of treating liver disease towards that of treating viral infections which happen to effect primarily the liver.

The management of chronic hepatitis B

The immediate goals of hepatitis B virus (HBV) therapy are to suppress the histologic progression of the disease and diminish infectivity. Although many drugs have been used in the treatment of this condition, only interferon has proven to be consistently effective. The ideal candidate for interferon therapy is a patient who has a high baseline aminotransferase level and a low HBV DNA level. Responders to interferon therapy usually demonstrate an alanine aminotransferase (ALT) flare to at least twofold the baseline value during the second or third month of therapy, indicating that the patient has become immunologically activated. Low baseline ALT levels before treatment (i.e., < 100 U/liter) are associated with a low response rate. An improvement in response rates occurs when patients with low ALT levels are primed with a short course of prednisone. Piecemeal necrosis markedly improves within a short time after a response is achieved, although residual portal tract inflammation often is demonstrated on biopsy. The loss of HBV DNA and hepatitis B e antigen is generally maintained after interferon therapy, but relapse occurs in approximately 10% of the patients. Further studies with interferon are indicated in multiple patient groups.