Variables that influence response to different interferon schedules in chronic hepatitis C and predictive models

Treatment of hepatitis C with interferon and ribavirin

Hepatitis C is a worldwide problem that frequently results in end-stage liver disease and its complications. Treatment for hepatitis C virus (HCV) has been rather ineffective but several recent studies have clarified the role of interferon and ribavirin therapy. In line with therapeutic progress in HIV infection, hepatitis C is now entering the era of multidrug antiviral therapy. Ribavirin is an orally active synthetic guanosine analogue with theoretical antiviral and immunomodulatory actions. In this review we have evaluated the role of interferon and ribavirin in treatment-naive patients, relapsers and non-responders. In naive patients the combination results in improved end-of-treatment and sustained response rates, with an overall 41% sustained virological response rate in patients treated for 48 weeks. Therapeutic benefit also extends to the traditionally difficult to treat patients (genotype 1, high vital load and advanced fibrosis). The addition of ribavirin to interferon has also resulted in an increased toxicity profile, which has made therapy more difficult for both the patient and managing physician. However, the significant improvement in response rates for all patients makes combination therapy the most appropriate choice as the first-line therapy for suitable patients with chronic viral hepatitis C. Appropriate management with interferon and ribavirin includes assessing the patient's HCV genotype to determine the optimal duration of therapy, assessing therapeutic efficacy by measuring HCV-RNA at 24 weeks and monitoring for the additional ribavirin side-effects.

New schedules of interferon for chronic hepatitis C

Current treatment regimens with either long-term interferon monotherapy or interferon-ribavirin combination achieve sustained response rates of 40-50%. Options to improve the sustained response to interferon include longer treatment duration, higher fixed doses throughout the course of therapy, de-escalating strategies in which more intensive treatment is given during the initial weeks of treatment (so-called induction dosing) or escalation strategies in which the dose is progressively increased until a response occurs. Published literature supports the use of a treatment period of at least 12 months. Although higher doses which are fixed throughout the treatment course result in a moderate increase in sustained response rate, this may not be justified by the cost and added side effects. Although high dose induction strategies may result in a more rapid decline in serum HCV RNA levels, it is not yet known whether this will result in better longterm outcome. Preliminary evidence suggests that the benefit may be confined to subgroups of patients who might be predicted to have a poor response to standard therapy, such as those with high pre-treatment viral levels.

Review article: interferon and hepatitis C--factors predicting therapeutic outcome

Hepatitis C chronically infects approximately 1.5% of Americans and is the most common clinical problem facing hepatologists. Since the virus was initially described in 1989, development of an effective therapy has been challenging. Although several different therapeutic agents have been used, no therapy has been shown to reliably eradicate the virus. Interferon-alpha, a cytokine with immunostimulatory and anti-viral properties, has become the therapy of choice for patients with chronic hepatitis C infection. Trials assessing the efficacy of interferon-alpha have characterized host and viral factors predictive of responses to treatment. A thorough understanding of these predictive factors is requisite to providing cost-effective therapeutic decisions for the patient with chronic hepatitis C infection.