Faculty Bibliography

Prospective, randomized, controlled, phase 3 clinical trials establish pegylated interferon (PEG-IFN) alfa plus ribavirin as the standard of care for patients with chronic hepatitis C. Such clinical trials are conducted in a highly regimented manner; patients must meet strict inclusion/exclusion criteria, and treatment is administered under rigid protocols with close monitoring by study personnel. Whether the results of phase 3 trials can be generalized or achieved in everyday clinical practice is questioned in several therapeutic areas. The efficacy of PEG-IFN alfa plus ribavirin therapy observed in pivotal phase 3 trials has been confirmed in several community-based trials conducted in North America and Europe, demonstrating consistent overall rates of sustained virologic response across a wide range of patient populations. Sustained virologic response rates stratified by genotype, viral load, fibrosis score, age, and ethnicity, factors known to impact treatment outcome, are consistent between these trials and comparable to those reported in clinical trials. The United States-based WIN-R trial confirmed the value of combining weight-based ribavirin dosing with weight-based PEG-IFN alfa-2b dosing across a spectrum of patient body weights. Large Canadian trials (POWeR and EAP), a German trial (AWB), a French study (Hepatys), and an Italian study demonstrated that PEG-IFN alfa plus ribavirin produces excellent efficacy in difficult-to-treat patient populations. Collectively, these results confirm the efficacy of current standard treatment regimens in a wide range of community-based settings, affording clinicians confidence that they can attain results similar to those of rigidly controlled randomized trials.

Standard therapy with pegylated interferon and ribavirin for chronic hepatitis C is effective in 40% to 50% of individuals with genotype 1 hepatitis C virus (HCV) infection and is associated with significant treatment-related toxicities. Newly developed small molecules that target key enzymes essential for HCV replication are in development. Telaprevir, a peptidomimetic inhibitor of the HCV NS3/4A protease, has shown great promise in early trials and is currently in advanced stages of clinical development. In treatment-naive patients and those with previous treatment failure, the addition of telaprevir to standard interferon and ribavirin therapy is well tolerated and enhances rates of sustained virologic response while shortening the treatment duration. In this report, the current experience using telaprevir to treat chronic HCV infection as monotherapy and in combination with other agents is reviewed.

Despite improvements to treatments for HCV infection, almost half of patients cannot be cured with standard combination therapy (pegylated interferon alpha and ribavirin). The HCV life cycle offers a number of potential targets for molecular therapy, and several specifically targeted antiviral therapies for HCV (STAT-Cs) are in preclinical and clinical stages of development. Evidence to date suggests that monotherapy with any antiviral drug is unlikely to eradicate HCV infection. Combination therapy with interferon and ribavirin is necessary for the augmentation of antiviral drug activity and/or prevention of drug resistance. Results from clinical trials carried out in the past few years on STAT-C agents in combination with standard therapy with peginterferon and ribavirin provide great promise of higher rates of sustained virological response and, potentially, shorter duration of therapy than standard therapy alone achieves. Although pegylated interferon and ribavirin are likely to remain a cornerstone of therapeutic regimens in the short term, combinations of antiviral drugs of different classes, possibly along with novel agents that target host factors and modulate viral replication or augment antiviral defenses, offer the eventual possibility of interferon-free regimens.

BACKGROUND: Current therapy for chronic hepatitis C virus (HCV) infection is effective in less than 50% of patients infected with HCV genotype 1. Telaprevir, a protease inhibitor specific to the HCV nonstructural 3/4A serine protease, rapidly reduced HCV RNA levels in early studies. METHODS: We randomly assigned patients infected with HCV genotype 1 to one of three telaprevir groups or to the control group. The control group (called the PR48 group) received peginterferon alfa-2a (180 microg per week) and ribavirin (1000 or 1200 mg per day, according to body weight) for 48 weeks, plus telaprevir-matched placebo for the first 12 weeks (75 patients). The telaprevir groups received telaprevir (1250 mg on day 1 and 750 mg every 8 hours thereafter) for 12 weeks, as well as peginterferon alfa-2a and ribavirin (at the same doses as in the PR48 group) for the same 12 weeks (the T12PR12 group, 17 patients) or for a total of 24 weeks (the T12PR24 group, 79 patients) or 48 weeks (the T12PR48 group, 79 patients). The primary outcome was a sustained virologic response (an undetectable HCV RNA level 24 weeks after the end of therapy). RESULTS: The rate of sustained virologic response was 41% (31 of 75 patients) in the PR48 group, as compared with 61% (48 of 79 patients) in the T12PR24 group (P=0.02), 67% (53 of 79 patients) in the T12PR48 group (P=0.002), and 35% (6 of 17 patients) in the T12PR12 group (this group was exploratory and not compared with the control group). Viral breakthrough occurred in 7% of patients receiving telaprevir. The rate of discontinuation because of adverse events was higher in the three telaprevir-based groups (21%, vs. 11% in the PR48 group), with rash the most common reason for discontinuation. CONCLUSIONS: Treatment with a telaprevir-based regimen significantly improved sustained virologic response rates in patients with genotype 1 HCV, albeit with higher rates of discontinuation because of adverse events. (ClinicalTrials.gov number, NCT00336479.)