Chronic hepatitis B: recommendations for therapy based on the natural history of disease in Australian patients

MAFLD Criteria May Overlook a Subtype of Patient with Steatohepatitis and Significant Fibrosis

INTRODUCTION

Metabolic associated fatty liver disease (MAFLD) is a novel concept for fatty liver disease. Different from non-alcoholic fatty liver disease (NAFLD), the diagnosis of MAFLD requires the presence of metabolic risks. This study aimed to characterize patients with liver steatosis but without metabolic risks (non-MR-steatosis) which may not be diagnosed by MAFLD criteria.

METHODS

Consecutive patients who underwent biopsy were included in this study. The clinic-pathological characteristics of non-MR-steatosis, NAFLD and MAFLD were compared.

RESULTS

A total of 1217 cases were included. There were 426 (35.00%) cases with MAFLD, 585 (48.07%) with NAFLD and 168 (13.80%) with non-MR-steatosis. The majority of the cases were infected with HBV (93.26%). The age and metabolic profiles were highest in MAFLD and lowest in non-MR-steatosis. The body mass index (BMI) level was also lowest in non-MR-steatosis (20.78 ± 1.54 kg/m²). The ALT and AST levels of the non-MR-steatosis group were not statistically different from those of MAFLD or NAFLD groups (p > 0.05). Histologically, there was no significant difference in the degrees of inflammation and fibrosis among the three groups. The severity of steatosis in non-MR-steatosis group was lower than MAFLD or NAFLD groups (p < 0.05). These results were consistent in both HBV and non-HBV subgroups.

CONCLUSION

MAFLD criteria may overlook some steatotic patients without metabolic risks, who may also have steatohepatitis and significant fibrosis.

Enhancing the hepatitis B care cascade in Australia: A cost-effectiveness model

If Australia is to successfully eliminate hepatitis B as a public health threat, it will need to enhance the chronic hepatitis B (CHB) care cascade. This study used a Markov model to assess the impact, cost and cost-effectiveness of scaling up CHB diagnosis, linkage to care and treatment to reach national and international elimination targets for hepatitis B in Australia. Compared to continued current trends, the model calculated the difference in care cascade projection, disability-adjusted life years (DALYs), costs and the incremental cost-effectiveness ratio (ICER), of scaling up CHB diagnosis, linkage to care and treatment to reach: (a) Australia's 2022 national targets and (b) the WHO's 2030 global targets. Achieving the national and WHO targets had ICERs of A$13 435 (A$10 236-A$21 165) and A$14 482 (A$13 031-A$25 641) per DALY averted between 2016 and 2030 in Australia, respectively. However, this excluded implementation and demand generation costs. The ICER for the National Strategy and WHO Strategy remained under A$50 000 per DALY averted if Australia spent up to A$328 or A$538 million, respectively, per annum (for 2016-2030) on implementation and demand generation activities. Sensitivity analysis showed that cost-effectiveness was predominately driven by the cost of CHB treatment and influenced by disease progression rates. Hence for Australia to reach the National Hepatitis B Strategy 2022 targets and WHO Strategy 2030 targets, it requires an improvement in the CHB care cascade. We estimated it is cost-effective to spend up to A$328 million or A$538 million per year to reach the National and WHO Strategy targets, respectively.

Frequency of interleukin 28B rs12979860 C>T variants in Filipino patients chronically infected with hepatitis B virus

Hepatitis B virus (HBV) is one of the most prevalent viral infections worldwide. Nearly 400 million individuals are chronic carriers of HBV. The aim of the present study was to determine the frequency of human interleukin 28B (IL28B) variants among treatment naive Filipino patients clinically diagnosed with chronic hepatitis B (CHB), and to compare the IL28B frequency distribution with various ethnic populations. Fifty-seven CHB patients and 43 normal controls were enrolled in this study. Real-time PCR was performed using the TaqMan genotyping assay for IL28B rs12979860. The allelic frequencies among normal controls were 0.94 and 0.06 for the IL28B rs12979860 C and T alleles, respectively. Eighty-eight percent were identified as homozygous for the IL28B C/C genotype and 12% were identified as heterozygous for the IL28B C/T genotype. Among CHB patients, the allelic frequencies were 0.90 for the IL28B C allele and 0.10 for the IL28B T allele. No IL28B T/T genotype was observed between the two groups. No significant difference in the distribution of IL28B genotypes was observed between normal controls and CHB patients. Allelic frequencies of IL28B among Filipinos were similar with other Asian populations but significantly different from Caucasians. The frequency of rs12979860 C>T variants among Filipino CHB patients has not yet been reported. These data provided new insight into the geographical frequency distribution of IL28B variants. Further studies are needed to determine the possible association between IL28B variants and response to pegylated-interferon-α plus ribavirin combination therapy among Filipino patients chronically infected with HBV.

Viral hepatitis B: clinical and epidemiological characteristics

It is now 50 years since the discovery of the hepatitis B virus (HBV), and, despite the availability of a prophylactic vaccine for more than 20 years, HBV infection remains a disease of significant global health burden. It is estimated that more than 240 million people are chronically infected with HBV and, therefore, are at risk for the development of cirrhosis, hepatic decompensation, and hepatocellular carcinoma (HCC). The risk of clinical complications has traditionally been higher in older males with hepatitis B e antigen (HBeAg)-positive disease, high-grade liver necroinflammation, and progressive fibrosis. Recent advances in the understanding of the natural history of chronic HBV infection have identified an important role for plasma HBV DNA levels as a marker of risk for clinical outcomes. Among adults, persistent high-level HBV replication is associated with an increased risk of cirrhosis, as well as HCC development. This has led to the therapeutic focus on achieving sustained viral suppression. There is an emerging role for quantitative hepatitis B surface antigen (HBsAg) levels as a marker of natural history. Low levels of HBsAg have been associated with sustained immune control, HBsAg seroclearance, as well as lower risk of HCC. In this work, we review the natural history of HBV infection, with a focus on the determinants of clinical outcomes in patients with chronic hepatitis B (CHB) infection.

IL28B genotype is not useful for predicting treatment outcome in Asian chronic hepatitis B patients treated with pegylated interferon-α

BACKGROUND AND AIM

IL28B genotype predicts response to pegylated interferon (peg-IFN)-based therapy in chronic hepatitis C. However, the utility of IL28B genotyping in chronic hepatitis B (CHB) cohorts treated with peg-IFN is unclear. It was investigated whether IL28B genotype is associated with peg-IFN treatment outcomes in a predominantly Asian CHB cohort.

METHODS

This was a retrospective analysis of CHB patients treated with 48 weeks of peg-IFN monotherapy. IL28B genotype (rs12979860) was determined (TaqMan allelic discrimination kit). Baseline hepatitis B virus (HBV)-DNA, alanine aminotransferase, and liver histology were available. The primary end-points were HBV e antigen (HBeAg) seroconversion with HBV-DNA < 2000 IU/mL 24 weeks post-therapy (HBeAg-positive patients) and HBV-DNA < 2000 IU/mL 24 weeks after peg-IFN (HBeAg-negative patients). The association between IL28B genotype and peg-IFN outcomes was analyzed.

RESULTS

IL28B genotype was determined for 96 patients. Eighty-eight percent were Asian, 62% were HBeAg positive, and 13% were METAVIR stage F3-4. Median follow-up time was 39.3 months. The majority of patients carried the CC IL28B genotype (84%). IL28B genotype did not differ according to HBeAg status. The primary end-points were achieved in 27% of HBeAg-positive and 61% of HBeAg-negative patients. There was no association between IL28B genotype and the primary end-point in either group. Furthermore, there was no difference in HBeAg loss alone, HBV surface antigen, alanine aminotransferase normalization, or on-treatment HBV-DNA levels according to IL28B genotype.

CONCLUSIONS

In the context of a small possible effect size and high frequency in Asian populations, IL28B genotyping is likely to have, at best, limited clinical utility for predicting peg-IFN treatment outcome for CHB patients in the Asia-Pacific region.

New insights into how HBV manipulates the innate immune response to establish acute and persistent infection

The mechanisms by which HBV establishes and maintains chronic infection are poorly understood. Although adult acquired HBV is generally cleared by a robust immune response, most individuals infected at childbirth or in very early childhood develop lifelong chronic infection. In addition, acute infections are unresolved in approximately 5% of individuals infected in adulthood. The host cell mechanisms that ensure establishment and resolution of acute infection and persistent infection remain unclear. Currently, two schools of thought suggest that either HBV is a 'stealth' virus, which initially establishes infection by avoiding host innate immune responses, or that HBV facilitates initial infection and progression to persistence by actively manipulating the host innate immune response to its advantage. There is increasing evidence that activation of innate host cell signalling pathways plays a major role in limiting adult acquired HBV infection and that, in turn, HBV has evolved numerous strategies to counteract these defence mechanisms. In this review, we summarize current knowledge regarding innate immune responses to HBV infection and discuss how HBV regulates cell signalling pathways to its advantage, particularly in the setting of chronic HBV infection. In turn, we show how an intimate knowledge of innate immune responses is driving development of novel therapeutic agents to treat chronic HBV infection.

Natural history of chronic hepatitis B in Euro-Mediterranean and African countries

Data derived from population, case-control, and cohort studies conducted in several Euro-Mediterranean and African countries disclose impressive similarities in the age and modes of hepatitis B virus (HBV) transmission and in the prevalence, duration, and outcome of the four phases of the natural history of chronic infection. Perinatal HBV infection is rare while the vast majority of chronic infections originate from horizontal HBV transmission to infants and children. HBeAg loss and seroconversion to anti-HBe occur in a few years time, usually during the second decade of life. HBeAg-negative/anti-HBe-positive chronic hepatitis B (CHB), predominates in these countries being 7-9 times more frequent than HBeAg-positive CHB. The predominance of HBeAg-negative CHB is largely linked to the molecular characteristics of HBV genotype D prevailing in European and African countries of the Mediterranean basin and of genotype E and subgenotype A1 that prevail in the other parts of Africa. The molecular characteristics of the African subgenotype A1 differ from those of European subgenotype A2 explaining the fact that patients infected subgenotype A1 demonstrate an earlier loss of HBeAg and seroconversion to anti-HBe during the natural course of HBV infection compared to those infected with subgenotype A2. It is proposed that the molecular characteristics of HBV genotypes and subgenotypes prevailing in Euro-Mediterranean and African countries acting in concert with host and environmental factors largely determine the natural history of chronic HBV infection and its significant differences from countries of HBV genotype C and B and of subgenotype Ae predominance. The knowledge of the natural history of chronic HBV infection in Euro-Mediterranean and African countries combined with wide screening programs for prompt recognition and treatment of chronic HBV infection both in its HBeAg-positive and -negative immune reactive phases can be expected to increase the efficacy of current and future therapeutic strategies.

Hepatitis B Knowledge, Testing, and Vaccination Among Chinese and Vietnamese Adults in Australia

Hepatitis B is a significant public health challenge within some subpopulations in Australia, including Chinese and Vietnamese migrants. There has been limited research on hepatitis B knowledge and actions in these communities. The authors conducted a self-administered survey among 442 Chinese and 433 Vietnamese in Brisbane. Generally, the knowledge is best described as “moderate.” One in 2 could not identify the sexual transmission risk and less than one third knew that sharing foods or drinks did not spread the disease. The majority of Vietnamese (80%) and 60% of Chinese respondents indicated prior testing. Vaccination was reported in 60% of the Vietnamese and in 52% of the Chinese. Knowledge was better among Chinese people who had been tested and vaccinated compared with those who were nontested and nonvaccinated. Only 3.5% of the Chinese, but 11.6% of the Vietnamese, indicated having a positive test result hepatitis B virus. This study helps identify strategies for programs targeting both communities and practitioners.

The linguistic demography of Australians living with chronic hepatitis B

OBJECTIVE

The prevalence of chronic hepatitis B virus (HBV) infection is increasing in Australia, and most affected individuals were born overseas. Estimating the English literacy of predominantly affected populations and determining the languages other than English (LOTE) spoken is essential for the development of appropriate resources.

METHOD

Data from the Australian Bureau of Statistics and Department of Immigration and Citizenship were used to estimate the number of Australian residents by birth country, English literacy and LOTE spoken, with a focus on those arriving in the past two decades. Prevalence of chronic HBV infection was estimated using source country seroprevalence. The results were compared to Victorian surveillance notification data and published Australian epidemiological and clinical studies.

RESULTS

Chinese languages and Vietnamese are the dominant languages spoken by Australians living with chronic HBV infection who speak limited or no English. Estimates of predominant source countries for people living with chronic HBV infection derived from Census data were generally coherent with existing epidemiological and clinical studies but differences exist, particularly for groups targeted for screening such as humanitarian entrants.

CONCLUSIONS

This study emphasises the need for LOTE resources for Australians living with chronic HBV infection and suggests priority languages. The notable differences observed between Census-derived estimates and surveillance data suggest there are particularly under-diagnosed groups within the community.

IMPLICATIONS

This study has clear implications for prioritising the translation of resources targeting Australians living with chronic HBV infection.

Geographical and genetic diversity of the human hepatitis B virus

Hepatitis B virus (HBV) is one of the most widely distributed viruses that infect humankind. Distinct clinical and virological characteristics of the HBV-infection have been reported in different geographical parts of the world and are increasingly associated with genetic diversity of the infecting virus. HBV is classified into genotypes and subgenotypes that are associated with ethnicity and geography. The genetic diversity of HBV in its various aspects has been the subject of extensive investigations during the last few decades. Since molecular epidemiology research tools have become widely available, the number of new publications in this field has grown exponentially. This review summarises the recent publications on the geographical distribution of genetic variants of HBV, and proposes updated criteria for the identification of new genotypes and subgenotypes of the virus.

Predictors and survival in hepatitis B-related hepatocellular carcinoma in New South Wales, Australia

BACKGROUND AND AIM

Incidence and mortality of hepatocellular carcinoma (HCC) has increased markedly over the last three decades in Australia. An increasing proportion of HCC cases is related to chronic viral hepatitis including hepatitis B virus (HBV) infection. However, there is very limited data on HBV-related HCC survival.

METHODS

Data on HBV-related HCC cases was obtained from a community-based linkage study. HCC cases notified to the New South Wales (NSW) Central Cancer Registry (CCR) during the period 1994-2002 were linked to HBV notifications from the NSW Health Department. Age, sex, country of birth, year of diagnosis, tumor stage were extracted from the CCR database. Survival analysis was conducted to determine median survival and identify predictors of survival.

RESULTS

Over the 9-year study period, 278 HCC cases were linked to chronic HBV infection. The majority of cases were male (83.5%) and overseas-born (93.6%); Asian-born cases accounted for 72.1%. Median survival following HCC diagnosis was 15.0 months. HCC survival was poorer among older age groups (P < 0.0001), and among cases with regional spread (hazard ratio, 3.23; 95% confidence interval, 1.83-5.69; P < 0.0001) and distant metastases (hazard ratio, 3.85; 95% confidence interval, 2.44-6.08; P < 0.0001). Sex, region of birth and study period (1994-1997 vs 1998-2002) were not associated with HCC survival.

CONCLUSION

The vast majority of HBV-related HCC were overseas-born, however, region of birth was unrelated to HCC survival. The continued extremely poor HCC survival, including lack of improvement in HCC survival in more recent years, suggests low uptake of HCC screening programs. Public health strategies including early diagnosis and appropriate referral for antiviral therapy assessment and increased HCC screening among high-risk populations are required to reduce HCC incidence and improve HCC survival.

Serum aminotransferase level and the risk of hepatocellular carcinoma: a population-based cohort study in Japan

Aminotransferase level is presumed to be a marker of hepatic inflammation, but uncertainty remains whether elevated aminotransferase levels are associated with an increased risk of hepatocellular carcinoma (HCC). We evaluated the incidence of HCC by aminotransferase level in 19 812 middle-aged and older individuals with and without hepatitis virus infection from a large-scale population-based cohort study (JPHC Study cohort II) in Japan. Hepatitis virus infection was identified at baseline in 1236 participants, namely 737 (3.7%) with hepatitis C virus, 479 (2.4%) with hepatitis B virus, and 20 (0.1%) with both. By the end of follow-up, a total of 109 newly arising HCC cases were diagnosed (71 men, 38 women), of which 87 (79.8%) had evidence of viral etiology. Alanine aminotransferase (ALT) was concentration-dependently associated with an increased risk of HCC in both virus-positive and virus-negative participants. Compared with virus-negative participants with ALT levels of less than 30 IU/l, a significant increase in the risk of HCC was observed in virus-negative participants with an ALT level greater than 30 IU/l, and in virus-positive participants with an ALT less than 30 IU/l, 30-69 IU/l, and > or =70 IU/l [Hazard ratio (95% confidence interval): 9.4 (3.9-22.3), 15.2 (6.1-37.6), 180.5 (89.4-364.2), 454.2 (221.5-931.2), respectively; P for trend <0.001]. In conclusion, our findings suggest that elevated ALT levels are strongly associated with the incidence of HCC regardless of hepatitis virus positivity. This finding indicates that ALT level is a good independent determinant of the need for intervention. Clinical application of these findings may help decrease HCC-associated mortality in hepatitis virus-endemic regions.

Genotype D amongst injection drug users with acute hepatitis B virus infection in British Columbia

The eight genotypes of hepatitis B virus (HBV) exhibit distinct geographical distributions. This study identified HBV genotypes and transmission modes associated with acute infection in British Columbia (BC), Canada, from 2001 to 2005. Seventy cases of acute HBV in BC were identified from laboratory reports using a standardized case definition. Interviews for risk factors and hepatitis history were conducted for each case. HBV genotypes were determined by BLAST comparison analysis of the surface (S) or preS gene sequence. To illustrate the distribution of genotypes identified amongst acute cases in BC, an annotated map was produced showing the global occurrence of HBV genotypes. The majority of acute HBV cases occurred in Caucasian, Canadian-born males, with 30% of cases reporting injection drug use (IDU) and 21% reporting incarceration. The most common genotype observed was genotype D (62.9%), followed by genotypes A (18.6%), C (11.4%), B (4.3%), and E (1.4%). A significant association was observed between Genotype D and IDU (P = 0.0025) and previous incarceration (P = 0.0067). Phylogenetic analysis of the S gene sequence demonstrated identical or high genetic relatedness amongst genotype D viral strains (86% sub-genotype D3), thus verifying transmission clustering amongst BC injection drug users. The association between acute HBV genotype and reported transmission modes has not been previously described in North America. Tracking of genotypes can help identify disease transmission patterns and target at-risk populations for preventive immunization.

Estimates and projections of hepatitis B-related hepatocellular carcinoma in Australia among people born in Asia-Pacific countries

BACKGROUND AND AIM

Australia has increasing immigration from hepatitis B virus (HBV) endemic countries of the Asia-Pacific region (APR). This study estimates immigration-related chronic HBV cases, chronic HBV prevalence, and HBV-related hepatocellular carcinoma (HCC) from 1960 to 2005 and projects HBV-related HCC to 2025 in Australia among people born in the APR.

METHODS

The populations of APR origin for the period 1960-2005 were derived from Australian census data. HBV prevalence from population-based sero surveys in the APR countries was used to estimate new chronic HBV cases (immigrant arrivals per year with chronic HBV). Age-specific incidence rates of HCC derived from a Taiwanese population-based study were used to estimate and project HBV-related HCC.

RESULTS

Chronic HBV cases among APR-born population increased rapidly from the late 1970s reaching a peak of 4182 in 1990. Chronic HBV prevalence increased to >53 000 in 2005. Estimates of HBV-related HCC increased linearly from one in 1960 to 140 in 2005, with a projected increase to 250 in 2025. Universal HBV vaccination programs in countries of origin had limited impact on projected HBV-related HCC to 2025.

CONCLUSION

The burden of chronic HBV including HBV-related HCC among APR-born Australians has increased over the past three decades and is projected to increase further during the next two decades.

Cost-effectiveness analysis of entecavir versus lamivudine in the first-line treatment of Australian patients with chronic hepatitis B

BACKGROUND

Chronic hepatitis B (CHB) virus infection is a major global healthcare problem. The recent introduction of entecavir in Australia for the treatment of CHB patients in the naive treatment setting has triggered significant optimism with regards to improved clinical outcomes for CHB patients.

OBJECTIVE

To estimate, from an Australian healthcare perspective, the cost effectiveness of entecavir 0.5 mg/day versus lamivudine 100 mg/day in the treatment of CHB patients naive to nucleos(t)ide therapy.

METHODS

A cost-utility analysis to project the clinical and economic outcomes associated with CHB disease and treatment was conducted by developing two decision-tree models specific to hepatitis B e antigen-positive (HBeAg+ve) and HBeAg-ve CHB patient subsets. This analysis was constructed using the Australian payer perspective of direct costs and outcomes, with indirect medical costs and lost productivity not being included. The study population comprised a hypothetical cohort of 1000 antiviral treatment-naive CHB patients who received either entecavir 0.5 mg/day or lamivudine 100 mg/day at model entry. The population of patients used in this analysis was representative of those patients likely to receive initial antiviral therapy in clinical practice in Australia. The long-term cost effectiveness of entecavir compared with lamivudine in the first-line treatment of CHB patients was expressed as an incremental cost per life-year gained (LYG) or QALY gained.

RESULTS

Results revealed that the availability of entecavir 0.5 mg/day as part of the Australian hepatologist's treatment armamentarium should result in significantly lower future rates of compensated cirrhosis (CC), decompensated cirrhosis (DC), and hepatocellular carcinoma (HCC) events (i.e. 54 fewer cases of CC, seven fewer cases of DC, and 20 fewer cases of HCC over the model's timeframe for HBeAg+ve CHB patients, and 69 fewer cases of CC, eight fewer cases of DC and 25 fewer cases of HCC over the model's timeframe for HBeAg-ve CHB patients). Compared with lamivudine 100 mg/day, entecavir 0.5 mg/day generated an estimated incremental cost per LYG of Australian dollars ($A, year 2006 values) 5046 and an estimated incremental cost per QALY of $A5952 in the HBeAg+ve CHB patient population, an estimated incremental cost per LYG of $A7063 and an estimated incremental cost per QALY of $A8003 in the HBeAg-ve CHB patient population, and an overall estimated incremental cost per LYG of $A5853 and an estimated incremental cost per QALY of $A6772 in the general CHB population.

CONCLUSION

The availability of entecavir in Australian clinical practice should make long-term suppression of hepatitis B virus replication increasingly attainable, resulting in fewer CHB sequelae, at an acceptable financial cost.

Identification of a novel hepatitis B virus precore/core deletion mutant in HIV/hepatitis B virus co-infected individuals

OBJECTIVES

Although HAART has resulted in improved health outcomes for most HIV-infected individuals, liver failure has emerged as a major cause of morbidity and mortality in people co-infected with hepatitis B virus (HBV). In HBV mono-infected individuals, core deletion mutants are associated with more aggressive liver disease. As HIV accelerates HBV liver disease progression, we hypothesized that HIV-HBV co-infected individuals have increased frequency of core mutations including deletions. To test this hypothesis, we have analysed genome-length sequences of HBV DNA from patients both prior to and during antiviral therapy.

SETTING

Prospective HIV/HBV co-infected cohort study.

METHODS

Genomic length HBV DNA was amplified by PCR from the serum samples of ten HIV/HBV co-infected individuals and five HBV mono-infected individuals prior to the commencement of lamivudine therapy and again after nine to 74 months of treatment. The complete genomes were sequenced and in order to further analyse some mutations, their frequency was determined in additional HIV/HBV co-infected and HBV mono-infected individuals.

RESULTS

A novel -1G mutation was identified in the HBV precore and overlapping core genes that truncated the deduced precore/core proteins. The mutant genome was the dominant species in some HIV/HBV co-infected individuals and was more prevalent in HIV/HBV co-infected individuals than HBV mono-infected individuals. The mutation was also associated with high HBV DNA concentrations in HIV/HBV co-infected individuals. Additional mutations were identified in the core/precore and polymerase genes and regulatory regions.

CONCLUSION

Mutations in the HBV core and precore genes may be contributing to disease pathogenesis in HIV/HBV co-infected individuals.

Lamivudine resistance in patients with chronic hepatitis B: role of clinical and virological factors

BACKGROUND

Lamivudine resistance is associated with long-term monotherapy for chronic hepatitis B and can lead to potentially serious clinical consequences. Scant information exists regarding the influence of hepatitis B virus variants in the development of resistance. The present study was designed to identify factors predictive of lamivudine resistance, with a particular focus on the role of precore and basal core promoter variants in the setting of hepatitis B e antigen-negative disease.

METHODS

Eighty-five patients, representing four major genotypes, were followed prospectively on lamivudine therapy. Resistance was defined as an increase in viral load, with polymerase gene sequencing confirming a lamivudine resistance mutation. Median follow up was 19 months (6-54 months). The Cox proportional hazards model was used to determine variables independently predicting for the early onset of lamivudine resistance.

RESULTS

The rate of lamivudine resistance was 6%, 31% and 51% at 12, 24 and 48 months, respectively. Multivariate analysis identified the precore variant, high baseline alanine aminotransferase (ALT), and persistent viremia (at 6 months) as independent predictors of the early development of lamivudine resistance, with rate ratios of 4.93 (95% confidence interval [CI]: 1.32-18.5), 1.22 (95%CI: 1.08-1.49), and 4.73 (95%CI: 1.49-15.0), respectively (P < 0.05). Female sex predicted early resistance (rate ratio 5.27 [95%CI: 1.23-22.5, P < 0.05]) although numbers were small (n = 12). Genotype did not influence treatment response nor time to onset of resistance.

CONCLUSION

Patients with precore variant hepatitis B virus are likely to develop lamivudine resistance early and should be considered for alternate first-line monotherapy. In the future, combination antiviral therapy may limit the development of resistance.

Management of chronic hepatitis B virus infection: a new era of disease control

When assessing patients with chronic hepatitis B virus (HBV) infection, consider the state of viral replication, the immune response and whether viral mutations could be present, as well as evidence for liver disease or extrahepatic manifestations. In wild-type infections, loss of hepatitis B e antigen (HBeAg), gain of anti-HBe and disappearance of HBV DNA from serum indicate immunosuppression of viral replication, or 'nonreplicative chronic HBV infection'. This 'healthy carrier' state must be distinguished from HBeAg-negative chronic hepatitis B (CHB) resulting from precore and core promoter mutations. HBeAg-negative CHB is common with genotypes D (Mediterranean region, south Asia) and C (north Asia) infections. Age, disease activity (alanine aminotransferase level) and severity (fibrosis stage, cirrhosis) influence treatment decisions. Following the marginal effectiveness of interferon and often temporary effectiveness of lamivudine due to drug resistance, treatment of CHB is entering a new era. Adefovir, entecavir, tenofovir, telbivudine and clevudine have equal or superior antiviral efficacy to lamivudine, whereas several agents are effective against lamivudine-resistant HBV. Pegylated-interferon (peginterferon) is superior to conventional interferon for obtaining sustained immunosuppression of HBV without drug resistance. Antiviral suppression of HBV replication for 2-5 years reverses hepatic fibrosis, prevents cirrhosis and, when cirrhosis is established, improves liver function, prevents hepatic decompensation and lowers the risk of liver cancer. Before embarking on immunosuppressive chemotherapy or organ transplantation in patients with chronic HBV infection, it is important to start antiviral therapy to prevent hepatitis flares. Antiviral therapy can be effective against membranous glomerulonephritis and polyarteritis nodosa caused by HBV. Further improvements in treatment of CHB are needed to prevent drug resistance and permanently suppress viral replication by eradicating viral templates or stimulating host immune responsiveness to HBV.

The clinical virology of hepatitis B

Hepatitis B virus (HBV) is a major human health problem as approximately 8% of the world’s population are chronic carriers and there are over a million HBV-related deaths annually. Treatment of HBV is extremely difficult, as the unique viral replication strategy results in both a continual source of stable DNA molecules that are the template for viral replication and gene expression, and a pool of viral quasispecies from which different isolates may emerge as selection pressures alter. Although the use of antiviral therapies has improved outcomes significantly for many chronically infected individuals, the emergence of drug-resistant and immune/vaccine-escape viruses ensures there is a continuing need for the development of new and imaginative approaches to control and eventually eradicate HBV.

A review of entecavir in the treatment of chronic hepatitis B infection

BACKGROUND

Infection with the hepatitis B virus (HBV) affects two billion people worldwide, and an estimated 400 million people are chronically infected. Currently, FDA-approved regimens for the treatment of chronic HBV include interferon-alpha2b, peginterferon-alpha2a, lamivudine, adefovir dipivoxil, and recently, entecavir.

OBJECTIVE

The purpose of this review is to evaluate the pharmacokinetic and pharmacodynamic properties, and the clinical efficacy and safety of entecavir in the treatment of nucleoside-naĩve and nucleoside-resistant HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB). SEARCH METHODOLOGY: Computerized searches of PubMed and International Pharmaceutical Abstracts from 1985 to July 10, 2005, were performed with the search headings: entecavir, BMS-200475, and chronic hepatitis B.

FINDINGS

Entecavir, a new deoxyguanosine analog, represents a third agent within the nucleoside/nucleotide HBV polymerase inhibitor class with distinct advantages over lamivudine and adefovir dipivoxil: it has a three-step mechanism of action, is the most potent inhibitor of HBV DNA polymerase, is not associated with any major adverse effects, and has a limited potential for resistance. In phase II and III clinical trials, entecavir was found to be superior to lamivudine for all primary endpoints evaluated in both nucleoside-naïve and lamivudine-resistant patients. Entecavir was effective in both HBeAg-positive and HBeAg-negative nucleoside-naïve patients. At this time, optimal duration of entecavir therapy is unknown.

CONCLUSION

Entecavir represents a new first- or second-line treatment option for patients chronically infected with HBV. Long-term efficacy and safety studies as well as studies of entecavir in combination with interferon products or other nucleoside/nucleotide analogs are eagerly awaited.