A review of the efficacy of adenine arabinoside and lymphoblastoid interferon in the Royal Free Hospital studies of hepatitis B virus carrier treatment: identification of factors influencing response rates

Genetic variability in hepatitis B viruses

In 1988, it was reported that the full nucleotide sequences of 18 hepatitis B virus (HBV) strains clustered into four genetic groups (A to D) with more than 8% divergence between the groups. This classification of strains in terms of genome sequence has since proven to be an important tool in the understanding of HBV epidemiology and evolution and has been expanded to include three more genotypes. In parallel with the HBV genotypes described in humans, HBV strains isolated from different primates and hepadnaviruses found in woodchucks, ground squirrels, ducks and herons have been studied. Sequence differences between HBV genotypes can lead to structural differences at the level of the pregenome and can also lead to dramatic differences at the translational level when specific and commonly occurring mutations occur. There is increasing evidence that the clinical picture, the response to treatment and the long-term prognosis may differ depending on which genotype has infected the patient. The consideration of traditional serological patterns in a patient must therefore take the genotype of the infecting strain into account. Nucleotide variability between HBV strains has been used in several studies to trace routes of transmission and, since it is becoming increasingly clear that the differences between HBV genotypes are important, the need for reliable and easy methods of differentiating HBV genotypes has arisen. This review summarizes the knowledge of HBV genotypes with regard to their genetic, structural and clinically significant differences and their origin and evolution in the context of the hepadnaviruses in general.

Treatment of chronic woodchuck hepatitis virus infection in the Eastern woodchuck (Marmota monax) with nucleoside analogues is predictive of therapy for chronic hepatitis B virus infection in humans

The woodchuck hepatitis virus (WHV) and its natural host, the Eastern woodchuck (Marmota monax), have been established as a model of hepatitis B virus (HBV)-induced disease. Several published studies have used this experimental animal model system to demonstrate potential antiviral therapies for chronic HBV infections. However, there has been little comparative information available on compounds used in clinical anti-HBV studies in WHV-infected woodchucks, thereby making interpretations of the potential relative effectiveness of new antiviral agents in humans more difficult. In this report, using a series of placebo-controlled studies, we compared the relative effectiveness of several nucleoside analogues that have been used in clinical trials for the treatment of chronic HBV infection against WHV replication in chronically infected woodchucks. Adenine-5'-arabinoside monophosphate (Ara-AMP [vidarabine]), ribavirin, (-)beta-L-2',3'-dideoxy-3'-thiacytidine (3TC [lamivudine]), and famciclovir (oral prodrug of penciclovir) induced depressions in viremia and intrahepatic WHV-DNA replication that were consistent with their relative effectiveness in anti-HBV human clinical trials. As observed in HBV-infected patients, 3' azido-3'-deoxythymidine (AZT [zidovudine]) had no effect on WHV replication in these studies. These experimental results more firmly establish chronic WHV infection in woodchucks as an accurate and predictive model for antiviral therapies against chronic HBV infection in humans and provide a baseline for comparative antiviral effects of other experimental antiviral agents in the WHV/woodchuck model system.

Relation between treatment efficacy and cumulative dose of alpha interferon in chronic hepatitis B. European Concerted Action on Viral Hepatitis (Eurohep)

BACKGROUND/AIMS

Alpha interferon (IFN) is an established treatment of chronic hepatitis B. The effect has been shown to be dose related, recommended dose regimens being associated with a doubling of the spontaneous, baseline HBeAg to anti-HBe seroconversion rate. However, the efficacy of IFN treatment in relation to the dose of IFN actually received remains to be established. The aim of this study was to estimate the relative efficacy of IFN as a function of the cumulative IFN dose. In addition we determined if and when a patient returns to his baseline chance of seroconversion after stopping IFN therapy.

MATERIALS AND METHODS

Individual patient data from 10 clinical controlled trials were available for the present analysis, in all, 746 patients, of whom 491 received IFN and 255 were untreated controls. The data were analyzed performing a time-dependent Cox regression analysis of the relative efficacy of IFN using the cumulative IFN dose administered up to any given time during the observation period and the time after termination of therapy as explanatory variables.

RESULTS

In the proposed model, the chance of HBeAg disappearance for a treated patient relative to no therapy was estimated to 2.1 at a cumulative dose of 100 MU and leveled out at about 2.8 at a cumulative dose of 500 MU. The effect of IFN was shown to decay rapidly after discontinuation and after 3 months a patient could be considered to be back to his baseline chance of HBeAg disappearance. These findings show that IFN administered at a dose of 15-30 MU/week should be considered effective (relative efficacy approximately 2) already after 1-2 months of treatment.

CONCLUSIONS

The present findings do not lend any support to the concept that IFN treatment becomes less effective when a certain total dose of IFN has been administered or that the treatment effect reaches beyond 3 months after stopping IFN.

Prednisolone withdrawal therapy enhances the effect of human lymphoblastoid interferon in chronic hepatitis B. INTERPRED Trial Group

BACKGROUND/AIMS

The aim of this multicentre, randomised, controlled, clinical trial was to evaluate the effect of prednisolone followed by lymphoblastoid interferon treatment in chronic hepatitis B.

METHODS

Two hundred and thirteen patients with chronic hepatitis B were randomised to either prednisolone (2 weeks of 0.6 mg/kg/day, 1 week of 0.45 mg/kg/day and 1 week of 0.25 mg/kg/day) or matching placebo followed by a 2-week rest phase and then human lymphoblastoid interferon 10 MU daily for 5 days followed by 10 MU thrice weekly for 11 weeks. Of 200 evaluable patients, 33 (16.5%) were females, and 50 (25%) were male homosexuals. Thirty three patients (16.5%) had chronic persistent hepatitis, 145 (72.5%) had chronic active hepatitis and 22 (11%) had active cirrhosis.

RESULTS

Survival analysis disclosed statistically significant effects of prednisolone pre-treatment on both HBeAg disappearance and HBeAg to anti-HBe seroconversion (log-rank test statistics 5.43; p = 0.02 and 4.75; p = 0.03). Observed HBeAg disappearance and HBeAg to anti-HBe seroconversion rates (placebo vs. prednisolone patients) were 28% vs. 44% and 23% vs. 38%. Six months after stopping interferon, HBV DNA was negative in 51% of prednisolone patients vs. 28% of placebo patients (Chi-square test statistic 6.13; p = 0.013). Prednisolone pre-treatment tended to be more effective in patients with higher transaminase levels and in patients with low levels of HBV DNA. Fifteen patients (7.5%) (13 within 1 year of follow-up) eventually lost HBsAg; 14 of these subsequently developed anti-HBs. Interferon treatment was modified in 102 patients (51%). Three out of 22 patients with cirrhosis (14%), one of whom received prednisolone pre-treatment, developed hepatic decompensation with a fatal outcome while on interferon treatment.

CONCLUSIONS

Prednisolone pre-treatment significantly enhanced the treatment effect of lymphoblastoid interferon in terms of HBeAg clearance and seroconversion to anti-HBe. Treatment should be used with caution in patients with cirrhosis and avoided in patients showing signs, or with a history, of decompensated cirrhosis.

Effects of acyclovir and vidarabin 5'-monophosphate on anti-duck hepatitis B virus in an in vitro culture system

Various anti-viral agents, e.g., interferon, have recently been used for the treatment of viral hepatitis. In the present study, duck hepatitis B virus (DHBV) was cultured in vitro and the anti-DHBV effects of acyclovir (ACV) and vidarabin 5'-monophosphate (VMP) were studied. The portal perfusion method was applied to the livers of 7-day-old white ducks weighing 100 g, bred in Japan, and hepatocytes were infected with DHBV in vitro. Duck hepatocytes infected with DHBV were cultured in medium containing ACV or VMP, and the anti-DHBV effects of these drugs were assessed by determining DHBV-DNA and duck hepatitis B surface antigen in the medium. Both ACV and VMP had anti-DHBV effects when used immediately after infection; however, both drugs were ineffective in hepatocytes obtained from a DHBV carrier duck. In conclusion, the anti-DHBV effects of these drugs were very limited. However, this culture system appears to be useful for studies of hepatitis virus and anti-viral drugs.

The treatment effect of alpha interferon in chronic hepatitis B is independent of pre-treatment variables. Results based on individual patient data from 10 clinical controlled trials. European Concerted Action on Viral Hepatitis (Eurohep)

Alpha interferon induces HBeAg seroconversion in about one third of treated patients and has become an established treatment of chronic hepatitis B. A number of smaller studies have suggested that response to treatment is more likely to occur in patients with higher levels of transaminases, with recent (adult) onset, a history of acute hepatitis, low levels of HBV DNA and in heterosexual males. The aim of this European co-operative study was to estimate the effect of alpha interferon more accurately and to evaluate the influence of host pre-treatment variables on the effect of interferon. Individual data were collected from 751 patients from 10 controlled clinical trials on alpha interferon (lymphoblastoid or recombinant) treatment for chronic hepatitis B. Alpha interferon was administered to 496 patients, while 255 were untreated controls. Individual patient data were analysed by survival analysis (log rank test and Cox regression analysis), stratified by trial, with the disappearance of HBeAg as the major endpoint. The results showed that the HBeAg disappearance rate with or without interferon treatment was higher in patients with high aminotransferase levels, with a history of acute hepatitis and in male heterosexual patients disregarding HIV status. If HIV-positive patients were excluded, the effect of sexual orientation was not significant. Therapy with alpha interferon increased the a priori HBeAg disappearance rate by a factor of 1.76; the relative treatment effect of alpha interferon was independent of the tested pretreatment host variables, but dependent on the total (intended) interferon dose (low dose < or = 200 MU/m2 increased HBeAg disappearance by a factor 1.37; medium/high dose > or = 200 MU/m2 increased HBeAg disappearance by a factor 2.05). In conclusion, this meta-analysis suggests that the effect of alpha interferon is less than previously assumed and independent of pretreatment host variables tested. It confirms the higher therapeutic benefit of a total dose exceeding 200 MU/m2 and of selection of patients based on disease activity and immune reactivity. Although all patient seem to have the same relative benefit, the absolute benefit of alpha interferon treatment seems to be greatest in patients with high transaminase levels and with a history of acute hepatitis.

beta 2-Microglobulin and antiviral therapy for chronic hepatitis type B

During a randomized controlled trial of interferon and descyclovir therapy, the beta 2-microglobulin and SGOT serum levels in 36 patients with chronic HBe-positive hepatitis B were studied in order to determine whether beta 2-microglobulin has prognostic value for HBe seroconversion. Pretreatment levels of beta 2-microglobulin were elevated in 39% of patients. Significant differences in mean beta 2-microglobulin activity and mean SGOT between treated patients and untreated controls were observed after 4 and 8 weeks of treatment (P less than 0.05). Levels in control patients remained stable. Prior to and during therapy, the mean elevation of beta 2-microglobulin and SGOT levels was similar in responders (N =7) and non-responders (N = 11). The outcome of antiviral therapy in our patients was not dependent on beta 2-microglobulin levels measured before or during interferon therapy.

Viral infections in the acquired immunodeficiency syndrome

The following communication is a tripartite synopsis of the role of viral infection in the acquired immunodeficiency syndrome (AIDS). The first section describes the impact of viral opportunistic infection in AIDS; for each virus, clinical presentation and diagnosis, laboratory diagnostic approaches (with emphasis on electron microscopy), and therapeutic interventions attempted to date are discussed. The second segment explores current theories on the pathogenesis of AIDS, and describes diagnostic and therapeutic approaches to the syndrome itself. The final section catalogues ultrastructural anomalies in the cells of AIDS patients, many of which have been mistakenly identified as etiologic agents.