Preclinical and clinical development of pegylated interferon-lambda 1 in chronic hepatitis C.

Current treatment of chronic hepatitis C consists of pegylated interferon-alpha (PEG-IFN-alpha) in combination with ribavirin. This regimen is associated with adverse effects that can limit its use. PEG-IFN-lambda 1 (pegIFNlambda) is a novel IFN that shares many of the biological effects of IFN-alpha but may have fewer side effects due to its more selective receptor distribution. Preclinical data show that pegIFNlambda has antiviral activity against hepatitis C virus (HCV) but does not inhibit myeloid colony formation. A phase 1 study in healthy volunteers demonstrated that pegIFNlambda is well tolerated. Elevated liver enzymes resulted in a dose-limiting toxicity after a single dose of 7.5 microg/kg, the highest dose tested. A phase 1b study in genotype 1 HCV patients who either relapsed after IFN-alpha therapy or naive to therapy was initiated. Interim data from the treatment relapse subset showed viral load reductions of 2.3 to 4.0 logs when pegIFNlambda was administered weekly as a single agent with or without ribavirin for up to 4 weeks. Drug-related side effects included elevation of liver enzymes. Decreases in hemoglobin were observed only in patients receiving ribavirin. Constitutional symptoms appeared lower than historical data for PEG-IFN-alpha. These results form the basis of further development of pegIFNlambda as a novel treatment for chronic hepatitis C.