Antiviral effect of prolonged intermittent lymphoblastoid alpha interferon treatment in chronic hepatitis B

Chronic hepatitis B virus and liver fibrosis: A mathematical model

Hepatitis B virus (HBV) infection is a liver disorder that can result in cirrhosis, liver failure and hepatocellular carcinoma. HBV infection remains a major global health problem, as it affects more 350 million people chronically and kills roughly 600,000 people annually. Drugs currently used against HBV include IFN-α that decreases viremia, inflammation and the growth of liver fibrosis, and adefovir that decreases the viral load. Each of these drugs can have severe side-effects. In the present paper, we consider the treatment of chronic HBV by a combination of IFN-α and adefovir, and raise the following question: What should be the optimal ratio between IFN-α and adefovir in order to achieve the best 'efficacy' under constraints on the total amount of the drugs; here the efficacy is measured by the reduction of the levels of inflammation and of fibrosis? We develop a mathematical model of HBV pathogenesis by a system of partial differential equations (PDEs) and use the model to simulate a 'synergy map' which addresses the above question.

Screening and identification of compounds with antiviral activity against hepatitis B virus using a safe compound library and novel real-time immune-absorbance PCR-based high throughput system

There are now seven nucleoside/tide analogues, along with interferon-α, that are approved by the FDA for the management of chronic hepatitis B virus (HBV) infection, a disease affecting hundreds of millions of people worldwide. These medications, however, are limited in usefulness, and significant side effects and the emergence of viral escape mutants make the development of novel and updated therapeutics a pressing need in the treatment of HBV. With this in mind, a library containing 2000 compounds already known to be safe in both humans and mice with known mechanisms of action in mammalian cells were tested for the possibility of either antiviral activity against HBV or selective toxicity in HBV producing cell lines. A modified real-time immune-absorbance-polymerase chain reaction (IA-PCR) assay was developed for this screen, utilizing cells that produce and secrete intact HBV virions. In this procedure, viral particles are first captured by an anti-HBs antibody immobilized on a plate. The viral load is subsequently assessed by real-time PCR directly on captured particles. Using this assay, eight compounds were shown to consistently reduce the amount of secreted HBV viral particles in the culture medium under conditions that had no detectable impact on cell viability. Two compounds, proparacaine and chlorophyllide, were shown to reduce HBV levels 4- to 6-fold with an IC₅₀ of 1 and 1.5 μM, respectively, and were selected for further study. The identification of these compounds as promising antiviral drug candidates against HBV, despite a lack of previous recognition of HBV antiviral activity, supports the validity and utility of testing known compounds for "off-pathogen target" activity against HBV, and also validates this IA-PCR assay as an important tool for the detection of anti-viral activity against enveloped viruses.

Peginterferon for the treatment of chronic hepatitis B in the era of nucleos(t)ide analogues

The practising clinician is currently faced with a number of effective treatment options for chronic hepatitis B, including two formulations of interferon (standard IFN and pegylated IFN) and five nucleos(t)ide analogues (lamivudine, adefovir, entecavir, telbivudine and tenofovir). Treatment strategies can be divided into those aiming for sustained response after discontinuation of therapy and those that need to be maintained by prolonged antiviral therapy. Sustained response is particularly achieved with interferon-based therapy, while treatment-maintained response can be achieved with long-term nucleos(t)ide analogue therapy in the majority of patients. Of currently available drugs for the treatment of chronic hepatitis B, PEG-IFN seems to result in the highest rate of off-treatment sustained response after a 1-year course of therapy. Sustained transition to the immune-control phase (inactive HBsAg carrier state) can be achieved in 30-35% of HBeAg-positive patients and 20-25% of HBeAg-negative patients. Loss of HBsAg has been observed in 11% of both HBeAg-positive and HBeAg-negative patients after 3-4 years. Since hepatitis B virus (HBV) genotype is an important predictor of response to PEG-IFN, determination of HBV genotype is essential in patients in whom sustained off-treatment response is pursued. Aiming for sustained response is of particular interest because many HBV-infected patients are in need of antiviral therapy at a young age and may otherwise require indefinite antiviral therapy.

Recombivax-HB: perspectives past, present and future

Hepatitis B disease has caused a heavy burden worldwide. The development of an immunogenic, efficacious and safe vaccine to combat this problem has already eased this burden to some extent. The incorporation of the vaccine into the infant and childhood immunization schedule has led to a decrease in the number of new hepatitis B cases reported each year, and there has been a significant decline in hepatocellular carcinoma in children. This implies that the future will see less hepatitis B disease as the infant and adolescent population that has been immunized ages, meaning that the disease burden should fall even further.

Long-term follow-up of alpha-interferon treatment of patients with chronic hepatitis B

Data on the long-term effects of interferon alfa (IFN) treatment on disease progression and mortality in patients with chronic hepatitis B (CHB) are limited. To evaluate factors that influence clinical outcome and survival, we performed a follow-up study on 165 hepatitis B e antigen (HBeAg) positive CHB patients treated with IFN between 1978 and 2002. The median IFN dose was 30 megaunits (MU)/week (range, 2-70 MU/week), and the median duration of therapy was 16 weeks (range, 1-92 weeks). Response to treatment was defined as HBeAg loss within 12 months after the end of IFN therapy. Median follow-up was 8.8 years (range, 0.3-24 years). Fifty-four patients (33%) responded to IFN treatment. Relapse (HBeAg reactivation) occurred in 7 of the 54 (13%) responders. Fifty-two percent of the responders lost hepatitis B surface antigen (HBsAg) as compared with 9% of the nonresponders (P <.001). Liver histology showed a decreased necroinflammatory activity and less progression of fibrosis in responders. Twenty-six patients died during follow-up. Hepatocellular carcinoma (HCC) was found in 8 patients, 6 of whom were nonresponders. Of the two responders who developed HCC, one patient had relapsed after discontinuation of therapy. Multivariate analysis showed significantly improved survival (relative risk (RR) of death 0.28, 95% CI 0.10-0.78) and reduced risk of developing HCC (RR 0.084, 95% CI 0.09-0.75) in responders. In conclusion, response to IFN therapy results in a prolonged clinical remission with an increased rate of HBsAg seroconversion and improved liver histology. Our results indicate that after correction for baseline factors, response to IFN therapy increases survival and reduces the risk of developing HCC.

Individualization of interferon therapy using serum hepatitis B virus DNA to reduce viral relapse in patients with chronic hepatitis B: a randomized controlled trial

OBJECTIVE

In patients with chronic hepatitis B, viral relapse following interferon (IFN) therapy may be the result of a treatment duration that is too short to prevent hepatitis B virus (HBV) from replicating later. To reduce viral relapse in patients with chronic hepatitis B who responded to IFN, we individualized the duration of therapy according to serum HBV-DNA levels.

METHOD

Treatment duration was prolonged to maintain negative serum HBV-DNA levels for the next 6 months in 30 patients who became HBV-DNA-negative following IFN therapy (group A). Another 35 patients were treated for only 6 months (group B). All patients had HBV-DNA as well as hepatitis B surface antigen (HBsAg) in their sera for more than 6 months and were proven histologically to have chronic hepatitis. Interferon alfa (IFN-alpha) was administered subcutaneously at a dose of 5 MU/m2 three times a week.

RESULTS

There were no differences in age, gender, hepatitis B e antigen (HBeAg) positivity, serum alanine aminotransferase (ALT) levels, or serum HBV-DNA levels between the two groups. The mean duration of IFN therapy in group A was 7.2 months. At the end of treatment, serum HBV-DNA was negative in 16 patients in group A and in 18 patients in group B. The loss of serum HBV-DNA was maintained to the end of follow-up in 13 patients in group A but in only eight patients in group B. Similarly, serum ALT levels were normal in 14 patients in group A but in only nine patients in group B at the end of follow-up.

CONCLUSION

Individualization of the duration of treatment to maintain serum HBV-DNA negativity for at least 6 months may reduce the viral relapse rate following IFN therapy.

Interferon monotherapy in chronic hepatitis B

Interferon-alpha (IFN-alpha) has been the only approved agent for the treatment of chronic hepatitis B in most countries, but this is rapidly changing. It is expensive, associated with frequent and unpleasant side effects, has limited efficacy and is ineffective in subjects with no/mild liver necro-inflammation. Loss of HBsAg and viral replication markers occur 6% and 20%, more often in IFN-treated subjects than controls. The most important factors that will predict favourable response to IFN-alpha therapy are elevated ALT and low serum HBV DNA levels. Chinese patients and children with active liver have similar response rates as Caucasian adults with equivalent ALT levels. Patients with HBeAg negative disease fare less well. Long-term follow up has shown that most IFN responders maintained their response although very few people have complete eradication of HBV.

Retreatment of chronic hepatitis B e antigen-positive patients with recombinant interferon alfa-2a. The European Concerted Action on Viral Hepatitis (EUROHEP)

Fifty-seven patients with chronic hepatitis B, hepatitis B virus (HBV) e antigen (HBeAg) and HBV DNA positivity, and aminotransferase elevation despite a previous course of any type of adequate interferon alfa (IFN-alpha) therapy were included in a multicenter prospective randomized controlled trial. The objective of the study was to compare a second course of IFN-alpha therapy (9 million units [MU] of IFN-alpha-2a, Roferon-A, thrice weekly for 6 months) versus no therapy in terms of loss of HBV DNA and HBeAg. At the end of the study, a sustained clearance of HBV DNA and HBeAg was observed in 9 of the 27 (33.3%) patients who had received retreatment with IFN-alpha compared with 3/30 (10%) patients who spontaneously cleared these markers in the untreated control group (chi2 = 4.66, P =.031; odds ratio: 4.5, 95%; confidence interval: 1.1-18.9). None of the responders lost HBsAg. Patients retreated with IFN-alpha were more likely to have biochemical remission in association with HBV clearance (5/27, 18.5%) compared with untreated patients (1/30, 3. 3%; Fisher's exact test P =.09 ). Histological improvement in the liver necroinflammatory activity was observed among sustained responders to IFN-alpha retreatment, consisting of regression of the portal and periportal inflammation and of the piecemeal necrosis; there was no change in the degree of liver fibrosis. Side effects were similar to those previously reported during IFN-alpha treatment; these were mild and reversible on IFN-alpha discontinuation. None of the baseline features were associated with response by Cox's regression analysis. In summary, viremic patients with chronic HBeAg-positive hepatitis may experience disease remission following retreatment with IFN-alpha. Thus, retreatment with IFN-alpha may be considered a therapeutic option.

Interferon alfa for chronic hepatitis B infection: increased efficacy of prolonged treatment. The European Concerted Action on Viral Hepatitis (EUROHEP)

Interferon alfa (IFN-alpha) is the primary treatment for chronic hepatitis B. The standard duration of IFN-alpha therapy is considered 16 weeks; however, the optimal treatment length is still poorly defined. We evaluated the efficacy and acceptability of prolonged IFN-alpha treatment in patients with chronic hepatitis B. To investigate whether treatment prolongation could enhance the rate of hepatitis B e antigen (HBeAg) seroconversion, we conducted a prospective, controlled, multicenter trial in which all patients were treated with a standard regimen of 10 million units IFN-alpha 3 times per week over 16 weeks. Patients who were still HBeAg-positive after 16 weeks of therapy were randomized to prolongation of the identical regimen up to 32 weeks (prolonged therapy) or discontinuation of treatment (standard therapy). Among the 162 patients who entered the study, 27 (17%) were HBeAg-negative after the first 16 weeks of treatment, and 118 were randomized to standard or prolonged therapy. After randomization, a response (HBeAg seroconversion and sustained hepatitis B virus [HBV]-DNA negativity) was observed in 7 of the 57 (12%) patients assigned to standard therapy versus 17 of the 61 (28%) patients assigned to prolonged therapy (P =.04). A low level of viral replication after 16 weeks of treatment, as indicated by serum HBV-DNA values under 10 pg/mL, was found to be the only independent predictor of response (52% vs. 0%; P <.001) during prolonged therapy. The prolonged IFN-alpha schedule was well tolerated in the large majority of patients. In chronic hepatitis B, prolongation of IFN-alpha therapy up to 32 weeks is superior to a standard course of 16 weeks. Those patients who exhibit a low level of viral replication at the end of the standard regimen benefit most from prolonged treatment.

Quantitative measurement of HBeAg in chronic hepatitis B: a comparison between a radioimmunoassay, a fluorescence ELISA and a chemiluminescence ELISA

The presence of the hepatitis B e antigen (HBeAg) in peripheral blood of chronic hepatitis B patients is a widely accepted marker of active replication of the hepatitis B virus. HBeAg determination during interferon therapy is a useful guide for the therapeutic regimen. The aim of the study was to compare the suitability of an HBeAg radioimmunoassay (RIA, Abbott Laboratories, North Chicago, IL, USA), the IMx-HBeAg assay (IMx, Abbott Laboratories) and the HBeAg/anti-HBe Amerlite assay (Amerlite, Johnson & Johnson Clinical Diagnostics, Cardiff, UK) for semiquantitative monitoring of HBeAg during therapy. HBeAg levels in serum samples obtained before and during interferon therapy were measured using an in-house standard calibrated against the Paul Ehrlich Institute HBeAg reference preparation (PEI standard). When serial dilutions of pretreatment serum samples were assayed by the three methods, radioimmunoassay was found to be highly sensitive although it had a very limited working range (0.5 to 12 PEI U/ml). A broader linear working range was observed for Amerlite (0.5 to 50 PEI U/ml) and the IMx assay (0.5 to 100 PEI U/ml). The intra-assay and interassay variations did not differ significantly. Since the IMx assay was less susceptible to sample variation and had a broad working range, semiquantitative measurement of HBeAg in one diluted and one undiluted sample by this assay may justifiably be introduced as routine procedure. Routine semiquantitative HBeAg measurement may improve individual dose adjustments and thus the success of interferon therapy.

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.

New developments in antiviral therapy for chronic hepatitis B infection

The standard treatment of an HBeAg-positive, HBV-DNA-positive chronic hepatitis B patient is a 16-week course of 10 MU alpha-interferon thrice weekly. However, the overall therapeutic effect, as measured by disappearance of the HBe-antigen, is estimated at 30%. Improvement is possible by better selection of the patient, modifications in the treatment schedule, or combination therapy. In the selection of possible candidates for combination therapy, the second generation nucleoside analogues with activity against hepatitis B are good candidates. In clinical studies, lamivudine and famciclovir are used, both of which can reduce serum HBV-DNA to levels below 1 pg/ml within weeks. The ongoing clinical studies address the efficacy and safety of these drugs after prolonged exposure, in combination with alpha-interferon and around liver transplantation in patients with decompensated liver disease.

The value of quantitative measurement of HBeAg and HBsAg before interferon-alpha treatment of chronic hepatitis B in children

Serum concentrations of HBsAg, HBeAg and hepatitis B virus DNA were measured quantitatively before interferon treatment in 23 children (17 boys, 6 girls) suffering from chronic hepatitis B, and correlated to the outcome of the treatment. Five children remained HBsAg- and HBeAg-positive throughout the treatment and 6 months after the end of the treatment (non-responders), 12 children eliminated HBeAg but not HBsAg (partial responders) and six eliminated HBeAg and HBsAg (complete responders). The five non-responders had significantly higher initial HBsAg and HBeAg concentrations and significantly lower alanine aminotransferase levels than the partial or complete responders. The six complete responders had significantly lower HBsAg concentrations than the partial or non-responders, and seemed to be younger. No significant difference in HBV DNA levels was found in the three response groups. These data suggest that quantitative assays of HBsAg and HBeAg are particularly useful in selecting patients with chronic hepatitis B for interferon therapy.

Interferon in chronic hepatitis B

In patients with typical chronic hepatitis B (HBsAg, HBeAg, HBV-DNA-positive), treatment with interferon-alpha must be carried out for 4-6 months on an alternate-day basis and dosage should be not less than 5 million units/square meter of body surface. The therapeutic response (i.e., clearance of replicative markers, transaminases normalization, histologic improvement) is achieved in about 40% of treated patients and the long-term beneficial effect is maintained in about 90% of them. Oriental HBV carriers, children, immunodeficient and highly viraemic patients are less likely to respond. Patients given combinations therapy (with steroids, antivirals, stimulators of the immune system) do not appear to gain more benefit from the association in comparison with treatment with interferon alone. Side-effects are usually minor (flu-like symptoms), but in a minority major adverse events have also been reported. In conclusion, interferon-alpha is effective in inhibiting viral replication but new therapeutic regimens and a better selection of patients are needed in order to induce persistent remissions and to reduce the cost benefit ratio.

Measurement of HBsAg to monitor hepatitis B viral replication in patients on alpha-interferon therapy

HBsAg was measured quantitatively in serum samples collected serially before and after the HBeAg seroconversion date from 69 patients with HBeAg seroconversion and 17 patients with both HBeAg and HBsAg seroconversion. In patients with only HBeAg seroconversion the median HBsAg level decreased from 8.39 micrograms/ml (range 0.01-57.51) before HBeAg seroconversion to 3.53 micrograms/ml (range 0.002-68.66) after seroconversion (P < 0.001). No significant drop in HBsAg was found for the control group (18 HBeAg-positive patients without seroconversion). From 12 other patients on alpha-interferon therapy HBsAg was quantitatively assayed monthly during and after therapy; HBsAg levels were compared to the levels of HBV-DNA and HBeAg. We observed a good correlation between the HBsAg level and both the HBV-DNA (r = 0.76; P < 0.001) and the HBeAg (r = 0.70; P < 0.001) level, irrespective of the response to alpha-interferon. Quantified assessment of HBsAg appears promising as a simple and cheap method for monitoring viral replication in chronic hepatitis B in patients undergoing interferon therapy.

Quantitative assessment of hepatitis B virus DNA in chronic hepatitis B: comparison of two solution hybridization assays

We compared two solution hybridization assays, the AffiProbe assay (Orion Corporation) and the Abbott HBV-DNA assay (Abbott), for quantitative measurement of hepatitis B virus (HBV) DNA in serum samples obtained from chronic hepatitis B surface antigen (HBsAg) carriers. Forty transversally collected (group 1) and 83 serially collected (group 2) serum samples from chronic hepatitis B patients were tested with both assays. The serial serum samples were obtained from 6 patients who underwent alpha-interferon therapy with different outcomes (nonresponse, hepatitis B e antigen [HBeAg] seroconversion, HBeAg and HBsAg seroconversion). In group 1 a good correlation (r = 0.91; P < 0.001) was found between the HBV-DNA results of the two assays. Two samples (5%) were HBV-DNA positive according to the Abbott but negative according to the AffiProbe assay; for all other samples the HBV-DNA status corresponded. In group 2 the assays gave colinear HBV-DNA results during follow-up of 5 of the 6 patients (correlation for the total group: r = 0.90; P < 0.001). Nevertheless, in both groups the AffiProbe assay yielded about 5-10 times higher HBV-DNA levels than the Abbott HBV-DNA assay (P < 0.001). These discordant results were most probably due to standardization differences of the positive control samples of the two test systems. This observation underlines the need for international standardization of HBV-DNA and uniform reference panels.

Repeated courses of alpha-interferon for treatment of chronic hepatitis type B

In chronic hepatitis B transition from active replication to viral latency (HBeAg seroconversion) usually leads to remission of the disease. alpha-Interferon (IFN) therapy induces HBeAg seroconversion in about one-third of the patients, thus leaving the majority of patients with persistent disease. Eighteen chronic hepatitis B patients who did not respond (HBeAg seroconversion and clearance of HBV-DNA) to an initial 16-week course of IFN subsequently received IFN again after at least 6 months of no therapy. The repeated therapy consisted of 1.5-5 MU lymphoblastoid IFN daily for 16 weeks. Treatment effects were monitored by quantitative measurement of HBeAg and HBV-DNA. To analyze whether the results were related to patient characteristics known to affect the response to initial treatment, a predicted response rate, based on pre-treatment factors, was determined. After a follow-up of 52 weeks, 2 of the 18 patients (11%) had responded to therapy. Two additional patients became HBV-DNA-negative with sustained HBeAg positivity. All patients remained HBsAg-positive. According to the pre-treatment parameters, a response was predicted for 9 of the 18 patients (50%). This predicted response rate was significantly higher than the actual response rate (p = 0.03). In conclusion, this pilot study with moderate dosages of IFN suggests that the HBeAg seroconversion rate after repeated IFN treatment is low for previous non-responders and probably is not related to important clinical characteristics that influence the response to initial IFN treatment. A large controlled trial with higher doses of IFN is desirable to further evaluate the benefits of retreatment.