Antiviral therapy for hepatitis B and C in Asians

Interferon alpha (IFNα)-induced TRIM22 interrupts HCV replication by ubiquitinating NS5A

TRIM22, a tripartite-motif (TRIM) protein, is upregulated upon interferon alpha (IFNα) administration to hepatitis C virus (HCV)-infected patients. However, the physiological role of TRIM22 upregulation remains unclear. Here, we describe a potential antiviral function of TRIM22's targeting of the HCV NS5A protein. NS5A is important for HCV replication and for resistance to IFNα therapy. During the first 24 h following the initiation of IFNα treatment, upregulation of TRIM22 in the peripheral blood mononuclear cells (PBMCs) of HCV patients correlated with a decrease in viral titer. This phenomenon was confirmed in the hepatocyte-derived cell line Huh-7, which is highly permissive for HCV infection. TRIM22 over-expression inhibited HCV replication, and Small interfering RNA (siRNA)-mediated knockdown of TRIM22 diminished IFNα-induced anti-HCV function. Furthermore, we determined that TRIM22 ubiquitinates NS5A in a concentration-dependent manner. In summary, our results suggest that TRIM22 upregulation is associated with HCV decline during IFNα treatment and plays an important role in controlling HCV replication in vitro.

Clinical trial: effects of adefovir dipivoxil therapy in Asian and Caucasian patients with chronic hepatitis B

BACKGROUND

Two-thirds of the 350 million people infected with chronic hepatitis B virus live in the Asia-Pacific region. AIM To compare the effects of adefovir dipivoxil therapy between Asian and Caucasian patients with chronic hepatitis B.

METHODS

The safety and efficacy of 10 mg of adefovir dipivoxil was compared to placebo in 501 Asian (n = 259) or Caucasian (n = 242) HBeAg+ and HBeAg- chronic hepatitis B virus patients treated for 48 weeks in two randomized, double-blind, placebo-controlled studies.

RESULTS

At week 48, histological improvement was observed in 60% and 56% of Caucasian and Asian patients, respectively. Change in serum hepatitis B virus DNA from baseline to week 48 for the adefovir dipivoxil-treated patients was -3.89 and -3.70 log(10) copies/mL in Caucasian and Asian patients, respectively, while 34 per cent of Caucasian patients and 39 per cent of Asian patients had undetectable serum hepatitis B virus DNA (<400 copies/mL) at week 48. The percentage of patients achieving alanine aminotransferase (ALT) normalization at week 48 was similar in both groups (Caucasian 64 per cent, Asian 63 per cent). No patients developed resistance through week 48. No differences in adverse events or grade 3 or 4 laboratory abnormalities were observed between groups.

CONCLUSIONS

There were no significant differences in treatment response between Asians and Caucasians. Adefovir dipivoxil was well tolerated and no resistance developed up to week 48 in both racial groups.

A dose-ranging study of the efficacy and tolerability of entecavir in Lamivudine-refractory chronic hepatitis B patients

BACKGROUND & AIMS

Entecavir is a nucleoside analogue with potent in vitro activity against lamivudine-resistant hepatitis B virus (HBV). This randomized, dose-ranging, phase 2 study compared the efficacy and safety of entecavir with lamivudine in lamivudine-refractory patients.

METHODS

Hepatitis B e antigen (HBeAg)-positive and -negative patients (n = 182), viremic despite lamivudine treatment for > or =24 weeks or having documented lamivudine resistance substitutions, were switched directly to entecavir (1.0, 0.5, or 0.1 mg daily) or continued on lamivudine (100 mg daily) for up to 76 weeks.

RESULTS

At week 24, significantly more patients receiving entecavir 1.0 mg (79%) or 0.5 mg (51%) had undetectable HBV DNA levels by branched chain DNA assay compared with lamivudine (13%; P < .0001). Entecavir 1.0 mg was superior to entecavir 0.5 mg for this end point (P < .01). After 48 weeks, mean reductions in HBV DNA levels were 5.06, 4.46, and 2.85 log(10) copies/mL on entecavir 1.0, 0.5, and 0.1 mg, respectively, significantly higher than 1.37 log(10) copies/mL on lamivudine. Significantly higher proportions of patients achieved normalization of alanine aminotransferase levels on entecavir 1.0, 0.5, and 0.1 mg (68%, 59%, and 47%, respectively) than on lamivudine (6%). One virologic rebound due to resistance occurred (in the 0.5-mg group).

CONCLUSIONS

In HBeAg-positive and HBeAg-negative lamivudine-refractory patients, treatment with entecavir 1.0 and 0.5 mg daily was well tolerated and resulted in significant reductions in HBV DNA levels and normalization of alanine aminotransferase levels. One milligram of entecavir was more effective than 0.5 mg in this population.

Chronic hepatitis B virus infection in the Asia-Pacific region and Africa: review of disease progression

Countries in the the Asia-Pacific region and Africa tend to have the highest prevalence of hepatitis B infection worldwide. Hepatitis B infection progresses from an asymptomatic persistently infected status to chronic hepatitis B, cirrhosis, decompensated liver disease and/or hepatocellular carcinoma. The aim of this review was to summarize rates and risk factors for progression between disease states in the Asia-Pacific region and Africa. A literature search was conducted employing MEDLINE and EMBASE (1975-2003) using the following key words: hepatitis B, natural history, disease progression, cirrhosis, hepatocellular carcinoma, mortality, Africa and the Asia-Pacific region. Bibliographies of articles reviewed were also searched. Ranges for annual progression rates were: (i) asymptomatic persistent infection to chronic hepatitis B, 0.84-2.7%; (ii) chronic hepatitis B to cirrhosis, 1.0-2.4%; and (iii) cirrhosis to hepatocellular carcinoma, 3.0-6.6%. Patients with asymptomatic persistent infection and chronic hepatitis B had relatively low 5-year mortality rates (<4%); rates (>50%) were much higher in patients with decompensated liver disease and hepatocellular carcinoma. No data were found for progression rates in African populations. Hepatitis B e antigen was a risk factor for chronic hepatitis B, and bridging hepatic necrosis in chronic hepatitis B increased the risk of cirrhosis. Risk factors for hepatocellular carcinoma included cirrhosis, co-infection with hepatitis C virus, and genetic and environmental factors. In this review, wide ranges of disease progression estimates are documented, emphasizing the need for further studies, particularly in Africa, where progression rates are largely not available. Summarizing information on factors associated with disease progression should assist in focusing efforts to arrest the disease process in those at most risk.

Chronic hepatitis B: a long-term retrospective cohort study of disease progression in Shanghai, China

BACKGROUND AND AIMS

The present study aimed to describe the disease progression of chronic hepatitis B patients without or with compensated cirrhosis at baseline, to estimate the risk of progression to decompensated cirrhosis, hepatocellular carcinoma and death, and to determine prognostic factors of disease progression in patients in Shanghai, China.

METHODS

Stored medical records from 322 biopsy-confirmed chronic hepatitis B cases diagnosed between 1981 and 1993 were selected, and the status of patients was tracked in 1999-2000. Among consenting patients, ultrasound examination and laboratory tests were conducted. Person-year incidence rates, Kaplan-Meier analysis, log-rank tests, and Cox regression analysis were conducted.

RESULTS

Among chronic hepatitis B patients without compensated cirrhosis, the incidence rates of decompensated cirrhosis, hepatocellular carcinoma, and death were 6.3, 2.8, and 7.6 per 1000 person-years, respectively, while for patients with compensated cirrhosis, the rates were 35.6, 8.2, and 35.2 per 1000 person-years, respectively. The 15-year survival rate was 88% for patients without compensated cirrhosis, compared with 56% for patients with compensated cirrhosis (P < 0.001). Cox regression analysis demonstrated that increased alpha-fetoprotein (AFP) (P < 0.01), gamma-globulin (P < 0.05), and high-level severity of hepatic fibrosis (P < 0.01) at baseline were risk factors of decompensated cirrhosis. Factors associated with a high risk of death included elevated AFP at baseline (P < 0.01), severity of hepatic fibrosis (P < 0.003), and sustained positivity for hepatitis B surface antigen (P < 0.004).

CONCLUSION

Increased AFP and severity of hepatic fibrosis at baseline were associated with higher risk of decompensated cirrhosis and death. These data provide rare empirical estimates of the negative long-term outcomes for patients with chronic hepatitis B in Shanghai, China.

Genotypic and phenotypic resistance: longitudinal and sequential analysis of hepatitis B virus polymerase mutations in patients with lamivudine resistance after liver transplantation

OBJECTIVE

Lamivudine-resistant strains appear in 27-62.5% of liver transplant recipients treated with lamivudine for hepatitis B virus (HBV) recurrence, and may lead to failure of antiviral therapy. In an extension of our previous study, we investigated the molecular events associated with the emergence of lamivudine-resistant mutants in this population.

METHODS

Sequential serum samples from 10 consecutive patients with lamivudine resistance after liver transplantation were analyzed for viral genotype, precore mutants, and viral polymerase gene mutants (L528M, M552V, M552I) using restriction fragment length polymorphism. Quantitative analysis of HBV DNA was performed using hybridization assay and polymerase chain reaction.

RESULTS

Eight patients (80%) were infected with genotype D and two (20%) with genotype C. Polymerase mutants (genotypic resistance) were identified in all the patients. Phenotypic resistance (rise in serum HBV DNA titers above the detection limit of the hybridization assay) developed in five patients (50%); of the remainder, three (30%) did not have phenotypic resistance, and two were primary nonresponders. Genotypic resistance was detected earlier than phenotypic resistance (median 285 days [range 42-510] vs median 387 days [range 320-420], p = 0.055). In five patients (50%), the emergence of the YMDD mutants took over the wild type; in three (30%), the YMDD mutant took over the wild type, but the wild type re-emerged during lamivudine therapy; and in two (20%), the YMDD mutants were detected in a mixture with the wild type (in different percentages). The mean pretreatment serum ALT level was significantly lower in the patients who did not develop phenotypic resistance (p = 0.0002). The M552I pure viral population was found mainly in these patients, and all retained stable graft function (median follow-up 33 months). A high pretreatment HBV DNA level (>50 x 10(6) copies/ml) was highly statistically significantly correlated with the rapid occurrence of phenotypic resistance (r = -0.90, p = 0.04).

CONCLUSIONS

We reached the following conclusions: 1) In our area, liver transplant recipients who develop resistance to lamivudine given for recurrent HBV infection seem to be mainly infected with genotype D. 2) Re-emergence of the wild type can occur during lamivudine therapy. 3) Genotypic resistance precedes phenotypic resistance, although phenotypic resistance does not always follow genotypic resistance. 4) Quantitative determination of viremia and analysis of polymerase gene mutants are recommended for monitoring antiviral therapy of liver transplant patients with HBV reinfection in the graft.

Long-term efficacy of interferon alpha-2b and lamivudine in combination compared to lamivudine monotherapy in patients with chronic hepatitis B. An Italian multicenter, randomized trial

BACKGROUND/AIMS

To evaluate the therapeutic efficacy of interferon alpha-2b and lamivudine in combination compared to lamivudine monotherapy in patients with chronic hepatitis B.

METHODS

One hundred and fifty-one patients were randomly assigned to receive either recombinant interferon alpha-2b (nine million units three times per week) and lamivudine (100 mg/daily per os) for 24 weeks or lamivudine alone (100 mg/daily per os) for 52 weeks. Patients were followed up for a further 48 weeks.

RESULTS

Sustained HBeAg seroconversion with undetectable serum levels of HBV DNA was observed in 25 of 76 patients (33%) treated with the combination therapy and in 11 of 75 patients (15%) treated with monotherapy (P=0.014). Histological improvement defined as a reduction of at least two points in the inflammation score as compared with pretreatment score was observed in 35 of 76 patients (46%) treated with combination therapy and in 20 of 75 patients (27%) treated with monotherapy (P=0.021). Both therapeutic regimens were well tolerated.

CONCLUSIONS

Six-month treatment with interferon alpha-2b and lamivudine in combination appeared to increase the rate of sustained HBeAg seroconversion compared to 1-year lamivudine monotherapy. However, the potential benefit of combining lamivudine and interferon should be investigated further in studies with different regimens of combination therapy.

Current Options for the Therapy of Chronic Hepatitis B Infection

Until recently the only available treatment for chronic hepatitis B was interferon-alpha. Over the past few years a new class of antiviral has become available, the reverse transcriptase inhibitors. Lamivudine is a nucleoside analogue reverse transcriptase inhibitor that was recently approved in many countries for the treatment of hepatitis B. Despite the potent action of lamivudine, the development of new antivirals and new strategies to treat hepatitis B are still the major goal. We review the latest options for therapy of chronic hepatitis B, including combination strategies that could be an approach to improving the response rate of antivirals.

The polymerase L528M mutation cooperates with nucleotide binding-site mutations, increasing hepatitis B virus replication and drug resistance

After receiving lamivudine for 3 years to treat chronic hepatitis B, 67-75% of patients develop B-domain L528M, C-domain M552I, or M552V mutations in the HBV polymerase that render hepatitis B virus (HBV) drug-resistant. The aim of this study was to evaluate the influence of these mutations on viral replication and resistance to antiviral agents. We investigated the replication fitness and susceptibility of the wild-type and five mutant HBVs (L528M, M552I, M552V, L528M/M552I, and L528M/M552V) to 11 compounds [lamivudine, adefovir, entecavir (BMS-200475) (+)-BCH-189 (+/-)-FTC (racivir) (-)-FTC (emtricitabine) (+)-FTC, L-D4FC, L-FMAU (clevudine), D-DAPD, and (-)-carbovir] by transfecting HBV DNA into hepatoma cells and monitoring viral products by Southern blotting. The replication competency of the single C-domain mutants M552I and M552V was markedly decreased compared with that of wild-type HBV. However, addition of the B-domain mutation L528M restored replication competence. Only adefovir and entecavir were effective against all five HBV mutants, and higher doses of these compounds were necessary to inhibit the double mutants compared with the single mutants. The B-domain mutation (L528M) of HBV polymerase not only restores the replication competence of C-domain mutants, but also increases resistance to nucleoside analogues.

Natural history of chronic hepatitis B virus infection

In chronic hepatitis B virus (HBV) infection acquired during adulthood, which is the type mostly seen in the Caucasian population, there is biochemical and histologic regression after HBeAg seroconversion, and the risk of death from hepatitis B-related causes is low. In chronic HBV infection acquired during birth or early childhood, which is the type most commonly seen in the Asian population, there is a prolonged phase of immunotolerance. The immune clearance phase is characterized by multiple acute exacerbations preceeded by elevations in serum HBV DNA levels, HBeAg concentration and HBeAg/anti-HBe immune complexes. Of these patients, 2.4% may develop hepatic decompensation during the stage of HBeAg seroconversion. The development of cirrhosis occurs more frequently in patients with episodes of decompensation and with repeated severe acute exacerbations. However progression to cirrhosis can be relatively silent and can occur even in children. After HBeAg seroconversion, precore and core promotor mutations occur frequently in the Asian population. However, there is little correlation between the occurrence of these mutations and alanine aminotransferase elevation in patients who are positive for anti-HBe. Although cirrhosis develops during the process of HBeAg seroconversion, 68% of the complications of cirrhosis and of hepatocellular carcinoma occur after HBeAg seroconversion. These complications may still occur even after HBsAg seroclearance.

Viral hepatitis A, B, and C

Mankind probably has known viral hepatitis for many centuries; however, the major and most dramatic developments in our knowledge of these diseases have taken place during the second half of the 20th century. During this relatively short period of time, the infectious nature of hepatitis A, B, and C has been proven, leading to their identification and description. The advent of serologic markers has provided the means for establishing the diagnosis. Epidemiologic studies have provided important information that led to exciting achievements in detection and prevention of transmission. Molecular biology studies and cell culture techniques have established our knowledge of the viral genomes, and led to the development of specific vaccines for hepatitis A and B. Anti-viral therapy has been developed and aggressive combination therapy has emerged as a promising strategy for chronic hepatitis B and C. This article reviews some of the main fields of progress and achievement related to viral hepatitis A, B, and C in the 20th century.