Interferon alfa-2b plus ribavirin for chronic hepatitis C patients who have not responded to interferon monotherapy

A cell-based assay for RNA synthesis by the HCV polymerase reveals new insights on mechanism of polymerase inhibitors and modulation by NS5A

RNA synthesis by the genotype 1b hepatitis C virus (HCV) polymerase (NS5B) transiently expressed in Human embryonic kidney 293T cells or liver hepatocytes was found to robustly stimulate RIG-I-dependent luciferase production from the interferon β promoter in the absence of exogenously provided ligand. This cell-based assay, henceforth named the 5BR assay, could be used to examine HCV polymerase activity in the absence of other HCV proteins. Mutations that decreased de novo initiated RNA synthesis in biochemical assays decreased activation of RIG-I signaling. In addition, NS5B that lacks the C-terminal transmembrane helix but remains competent for RNA synthesis could activate RIG-I signaling. The addition of cyclosporine A to the cells reduced luciferase levels without affecting agonist-induced RIG-I signaling. Furthermore, non-nucleoside inhibitor benzothiadiazines (BTDs) that bind within the template channel of the 1b NS5B were found to inhibit the readout from the 5BR assay. Mutation M414T in NS5B that rendered the HCV replicon resistant to BTD was also resistant to BTDs in the 5BR assay. Co-expression of the HCV NS5A protein along with NS5B and RIG-I was found to inhibit the readout from the 5BR assay. The inhibition by NS5A was decreased with the removal of the transmembrane helix in NS5B. Lastly, NS5B from all six major HCV genotypes showed robust activation of RIG-I in the 5BR assay. In summary, the 5BR assay could be used to validate inhibitors of the HCV polymerase as well as to elucidate requirements for HCV-dependent RNA synthesis.

Current antiviral combination therapy for chronic hepatitis C patients who failed to interferon alfa-based treatment

WHAT IS KNOWN AND OBJECTIVE

Interferon-alfa-based therapy is effective in the treatment of Hepatitis C. However, some patients fail to respond and others relapse, after initially responding. Our objective was to assess the efficacy, safety and predictive factors for sustained virological response (SVR) to peginterferon plus ribavirin in chronic hepatitis C patients who failed to interferon-alfa (IFNα)-based therapy.

METHODS

Seventy-five consecutive patients who failed to IFNα-based therapy were retreated with peginterferon plus ribavirin. Of these patients, 85% were infected by genotype 1. The primary endpoint was SVR.

RESULTS AND DISCUSSION

Of 75 non-responder (n = 54) or relapser patients (n = 21), 50 were previously treated with IFNα-monotherapy and 25 with IFNα plus ribavirin. Global SVR rate was 41.3%: for patients re-treated with IFNα the response was 48% whilst for those retreated with IFNα plus ribavirin, it was 28%. For previous non-responders the SVR rate was 37% and for relapsers it was 52.4%.

WHAT IS NEW AND CONCLUSION

Retreatment with peginterferon plus ribavirin is an effective option for some chronic hepatitis C non-responder or relapser patients. Higher SVR rate was achieved in relapsers and in those patients who received IFNα monotherapy previously.

Combination Therapy of Interferon and Ribavirin Versus Interferon Monotherapy in Treatment of Chronic Hepatitis C: A Meta-analysis of Clinical Trials

This meta-analysis was conducted to assess the efficacy and safety of interferon and ribavirin combination therapy (CT) versus interferon monotherapy (IMT) in inducing sustained response in interferon-naïve, relapser, and nonresponder chronic hepatitis C patients. A literature search was performed using the MEDLINE database for clinical trials published in the period between 1995 and 2003. A total of 31 randomized trials and 7 nonrandomized trials comparing CT with interferon alone or comparing different dose regimens of CT were included in this meta-analysis. The primary outcome measure was sustained virological response. The summary estimate of the odds ratio was obtained using the random effect model. The study showed that sustained virological response rate was significantly higher in interferon-naïve, relapser, and nonrespondent chronic hepatitis C patients who were on CT compared to IMT (odds ratio = 3.23, 17.65, and 4.71, respectively). There was no statistically significant difference in virological and biochemical responses between different dose regimens of CT. Side effects, dose reduction, and treatment discontinuation rates were significantly higher in patients receiving CT compared with IMT. Treatment with interferon plus ribavirin has a significant benefit on the virological and biochemical response in patients with chronic hepatitis C irrespective to the previous treatment, and it should be considered the treatment of choice in naïve, relapser, and nonrespondent chronic hepatitis C patients.

Therapeutic modalities in hepatitis C: challenges and development

Our understanding of the pathogenicity of hepatitis C virus (HCV) is based on patients infected chronically for >20 years. The lack of a suitable animal model, the narrow host range of the virus, and the protracted onset of liver disease induced by HCV have hampered advances in treatment. In spite of these problems, we identified patient and viral characteristics that predict responses to current therapies, including HCV genotype, viral load, body weight, age, liver histology, co-infection with HIV and treatment adherence and tolerance. Interferon (IFN) alpha was the first therapy for chronic HCV infection. The combination of IFN plus ribavirin increases sustained virological response rates compared with IFN alone. Two pegylated IFNs have been developed and are widely approved for the treatment of chronic hepatitis C: peginterferon alpha-2a (40 KD), and pegylated IFN alpha-2b (12 KD). These products have reduced systemic clearance, prolonged half-lives and reduced antigenicity compared with conventional IFN. The reduced clearance results in sustained plasma levels of the drug and allows for once-weekly dosing. Pegylated IFN alpha-2b (12 KD) has a small, linear polyethylene glycol (PEG) moiety and has an intermediate duration of activity; peginterferon alpha-2a (40 KD) incorporates a large, branched-chain PEG moiety and has a longer half-life than both conventional IFN alpha and pegylated IFN alpha-2b (12 KD). The combination of a pegylated IFN plus ribavirin significantly increases sustained virological response rates compared with conventional IFN plus ribavirin in patients with chronic hepatitis C and is now recognized as the standard of care for these patients.

Low daily dosage of interferon for 1 year after HCV-related end-therapy response. A randomized-controlled study

This randomized controlled study involved 236 1b genotype (121 males) naive patients with chronic hepatitis C. After a course of interferon (IFN)-alpha2b plus ribavirin for 6 or 12 months, 117 (49.5%) of the end-therapy responders were equally divided into two groups and were assigned to receive either low daily doses of IFN-alpha2b (1.5 MU) 'consolidation therapy' (59 patients) for 1 year or no further treatment (58 patients). At the end of the follow-up period (6 months), the number of sustained responders in the consolidation group (83%) was significantly higher than in the control group (37.9%). The predicting factors of both end-therapy response and sustained response were the classic ones and a lower GGT/ALT ratio (GGT: gamma-glutamyl transpeptidase; ALT: alanine aminotransferase). The strongest predictors of sustained response alone were consolidation therapy and the longer period on combined treatment (12 vs 6 months). Consolidation therapy was better tolerated than the previously prescribed combined therapy in terms of side effects. In conclusion, genotype 1b naive end-therapy responders to usual combined therapy, after a period of daily consolidation therapy with a low dosage of IFN without ribavirin, achieved a better rate of sustained response than the control group.

Impact of high-dose interferon induction and ribavirin therapy in patients with chronic hepatitis C relapsing after or not responding to interferon monotherapy

BACKGROUND/AIMS

Initial high-dose interferon-alpha induction therapy in combination with ribavirin improves sustained response rates in treatment-naïve patients. This prospective, randomized, controlled study tested whether non-responders or relapsers to interferon monotherapy also benefit from induction therapy.

METHODS

Patients with chronic hepatitis C who had not responded to (n=75) or relapsed (n=80) after previous interferon therapy were randomized to receive three different interferon doses during the first 14 weeks of therapy (A: 10 MU IntronA/day for 2 weeks, followed by 10 MU/2 days for 12 weeks; B:5 MU/d for 14 weeks; C: 5 MU/2 days for 14 weeks) followed in all by 5 MU/2 days for 24 weeks. All patients received 1-1.2 g ribavirin/day throughout the whole study.

RESULTS

The rates of viral clearance at any time on treatment were similar in all groups. Sustained response rates were also not different among the groups in interferon nonresponders (A 32%, B 29%, C 31%) and relapsers (A 64%, B 68%, C 71%), respectively, as well as in patients with different genotypes. As expected, sustained response rates were higher in patients with genotype non-1 than in those with genotype 1.

CONCLUSION

High-dose induction therapy does not improve the outcome of interferon/ribavirin therapy in interferon nonresponders or relapsers.

Retreatment with interferon plus ribavirin of chronic hepatitis C non-responders to interferon monotherapy: a meta-analysis of individual patient data

BACKGROUND AND AIMS

Retreatment with a combination of alpha interferon (IFN) plus ribavirin of patients with chronic hepatitis C who did not respond to IFN monotherapy has not been assessed in large controlled studies.

METHODS

To assess the effectiveness and tolerability of IFN/ribavirin retreatment of non-responders to IFN and to identify predictors of complete (biochemical and virological) sustained response, we performed a meta-analysis of individual data on 581 patients from 10 centres. Retreatment with various IFN schedules (mean total dose 544 mega units) and a fixed ribavirin dose (1000-1200 mg/daily depending on body weight) was given for 24-60 (mean 39.5) weeks.

RESULTS

Biochemical end of treatment and sustained responses were observed in 271/581 (46.6%; 95% confidence interval (CI) 42.6-50.7%) and in 109/581 (18.7%; 95% CI 15.6-22.0%) cases, respectively. Two hundred and six of 532 patients (38.7%; 95% CI 34.6-42.9%) had an end of treatment complete response to retreatment while a complete sustained response occurred in 88 of 559 (15.7%; 95% CI 12.8-18.8%). Fifty four of 581 patients (9.2%; 95% CI 7.0-11.7%) stopped retreatment due to adverse effects. By logistic regression, complete sustained response was predicted independently by age <45 years (p=0.04), by normal pretreatment gamma-glutamyltransferase levels (p=0.01), and by a second course total IFN dose of at least 432 mega units (p=0.008).

CONCLUSIONS

The overall low probability of effectiveness argues against indiscriminate retreatment of all IFN monotherapy non-responders with IFN/ribavirin. Patients less than 45 years old with normal gamma-glutamyltransferase levels who were retreated with high dose long course combination therapy had a complete sustained response rate of 30%.

Meta-analysis: combination therapy with interferon-alpha 2a/2b and ribavirin for patients with chronic hepatitis C previously non-responsive to interferon

BACKGROUND

The efficacy of interferon-alpha plus ribavirin treatment for patients not responding to interferon monotherapy is not well established.

AIM

To assess the efficacy and safety of combination therapy with interferon-alpha 2a/2b plus ribavirin by performing a meta-analysis of randomized clinical trials.

METHODS

A systematic search of electronic databases for randomized clinical trials of interferon-alpha 2a/2b plus ribavirin was conducted independently by two investigators. Data abstraction was performed. The primary end-point was a sustained virological response. Estimates of the common odds ratio were calculated using a random effects model.

RESULTS

Of the 127 identified studies, 46 were considered for evaluation and 10 were included (1728 patients). The pooled sustained virological response was 12.6% (95% CI, 9.5-16.3%) for combination therapy vs. 2% (95% CI, 0.9-4.0%) for interferon monotherapy, with a common odds ratio of 5.49. Higher doses of interferon, a longer duration of therapy (48 weeks) and genotypes other than 1 and 4 were associated with an improvement in response. More side-effects and discontinuations were observed with combination therapy than with interferon monotherapy.

CONCLUSIONS

Non-responders to interferon may benefit from re-treatment with combination therapy, especially from a 48-week regimen.

Interferon-alpha-2b plus ribavirin: a review of its use in the management of chronic hepatitis C

Relatively few patients (< or =20%) with chronic hepatitis C achieve a sustained virological response after interferon-alpha monotherapy. Hence, alternative treatment strategies such as the addition of the broad spectrum antiviral agent ribavirin to interferon-alpha-2b have been investigated. Combination therapy with subcutaneous interferon-alpha-2b [3 million units (MU) three times per week] plus oral ribavirin (1000 to 1200 mg/day) has proven effective in several well designed trials of 24 to 48 weeks' duration in adult patients with compensated chronic hepatitis C. Compared with interferon-alpha-2b (3 or 6 MU three times per week) with or without placebo, combination treatment with interferon-alpha-2b plus ribavirin significantly enhanced end-of-treatment and sustained virological and biochemical response rates in treatment-naive and treatment-experienced patients [sustained virological response rates in treatment-naive recipients (6 to 19% vs 31 to 43% of patients); sustained overall (virological plus biochemical) response rates in nonresponders to (1 vs 14%) or relapsers (4 to 5% vs 30 to 44%) after previous interferon-alpha monotherapy]. Forty-eight weeks of combination therapy was superior to 24 weeks in treatment-naive patients infected with hepatitis virus C (HCV) genotype 1, whereas response rates were similar at 24 and 48 weeks in those infected with other HCV genotypes. Furthermore, there were marked improvements in histological inflammatory scores in patients who responded to treatment with either interferon-alpha-2b plus ribavirin or interferon-alpha-2b alone. Although adverse events associated with either drug during combination therapy occurred frequently, these were generally mild to moderate in intensity and were consistent with those reported for each individual agent. Twenty-six percent of patients required dosage modifications of one or both drugs during combination therapy.

CONCLUSIONS

Interferon-alpha-2b plus ribavirin is an efficacious first- and second-line therapy in adult patients with compensated chronic hepatitis C, significantly improving sustained virological and biochemical responses versus interferon-alpha-2b monotherapy. The tolerability profile of interferon-alpha-2b plus ribavirin therapy is consistent with the individual profiles of these agents with no evidence of additive effects. The place of interferon-alpha-2b plus ribavirin combination therapy in relation to newer agents, including pegylated interferons-alpha and other multidrug regimens, remains to be determined in this rapidly evolving area of therapeutic management. Currently, combination therapy with interferon-alpha-2b plus ribavirin is recommended as first-line therapy for patients with chronic hepatitis C and compensated liver disease, and is an option for use as second-line therapy in those who have relapsed after, or failed to respond to, previous treatment with interferon-alpha.

Interferon-alpha plus ribavirin for 12 months increases the sustained response rates in chronic hepatitis C relapsers

BACKGROUND

The effectiveness and tolerability of combination therapy for 12 months have not been evaluated sufficiently in chronic hepatitis C relapsers to interferon.

AIMS

To evaluate the sustained response to interferon plus ribavirin for 12 months in chronic hepatitis C relapsers.

METHODS

We included 55 chronic hepatitis C relapsers in a 12-month treatment protocol with interferon (3 MU thrice weekly) plus ribavirin (1-1.2 g/day). The effectiveness was evaluated using serum aminotransferase and hepatitis C virus RNA levels, alanine aminotransferase normalization and viraemia clearance after 12 months, defining the end-of-treatment response, and 6 months after completion of therapy, defining the sustained response. Adverse effects were recorded.

RESULTS

End-of-treatment response and sustained response were achieved in 47 (85%) and 37 (67%) patients, respectively; there were 10 (21%) relapsers after combination therapy. Predictive factors of sustained response included the genotype (non-1 95% vs. 1 48%; P < 0.001), lower viraemia (503 917 +/- 553 230 vs. 901 393 +/- 548 267 copies/mL; P < 0.005), higher alanine aminotransferase levels (137 +/- 75 vs. 103 +/- 41 IU/L; P < 0.05) and a lower gamma-glutamyl transpeptidase/alanine aminotransferase ratio (0.30 +/- 0.23 vs. 0.49 +/- 0.39; P < 0.05). Tolerance to therapy was good, with no withdrawals.

CONCLUSIONS

Interferon plus ribavirin treatment for 12 months in chronic hepatitis C relapsers yields high sustained response rates and is well tolerated. The sustained response is related to a non-1 genotype, lower baseline viraemia, higher alanine aminotransferase level and a lower gamma-glutamyl transpeptidase/alanine aminotransferase ratio.

High-dose prolonged combination therapy in non-responders to interferon monotherapy for chronic hepatitis C

BACKGROUND

Therapy of chronic hepatitis C non- responders to interferon monotherapy with standard doses of interferon plus ribavirin is usually ineffective.

AIM

To evaluate the efficacy and tolerability of high-dose prolonged combination retreatment in non- responder patients.

METHODS

Patients were retreated for 6 months with 6 MU alphaIFN on alternate days and 1000 or 1200 mg/day ribavirin. HCV-RNA negative patients continued therapy for an additional 6 months.

RESULTS

Forty patients (29 males, mean age 49.7 years, 34 genotype 1b, 11 with F3 fibrosis) were treated. At 6 months, 20 (50%) patients were HCV-RNA negative but six of them discontinued therapy because of adverse events. A sustained response was achieved in 28% of patients (11/40). A sustained response was more frequent among patients with genotype non-1b than in those with genotype 1b (67 vs. 21%, P=0.005) and clearance of HCV-RNA in the first 3 months had a high predictive value for sustained response (100% of sustained responders vs. 24% of non-responders, P=0.0001).

CONCLUSIONS

High-dose prolonged combination therapy in non-responders to IFN monotherapy leads to a higher rate of sustained response than the standard combination regimen. Tolerability may be a rate-limiting factor. Maximal effectiveness can be predicted in patients with non-1b genotype and in those who clear HCV-RNA soon after starting retreatment.

[Why are not all patients with chronic liver disease associated with hepatitis C virus treated?]

AIMS

To analyze the prevalence of patients with chronic liver disease associated with hepatitis C virus (HCV) not undergoing antiviral treatment and the reasons for which this treatment was not indicated.

PATIENTS AND METHODS

718 patients with HCV infection referred for therapeutic evaluation between January 1990 and January 1998. Demographic, clinical, biological and histological variables were prospectively analyzed. The patients were divided into two groups: treated and untreated.

RESULTS

393 patients were treated and in 325 patients antiviral treatment was not considered to be indicated. The most frequent reasons for not starting therapy were advanced age, the presence of decompensated cirrhosis and the patients' refusal to undergo antiviral treatment.

CONCLUSIONS

A broad subgroup of patients with chronic liver disease associated with HCV do not receive antiviral treatment. This is related with: a) patients' advanced age at diagnosis, b) diagnosis at the advanced stages of the disease, and c) patients' refusal to undergo such treatment after being informed of its potential risks and benefits.