The US Food and Drug Administration has granted fast track designation to Schering Plough's investigational oral hepatitis C protease inhibitor (SCH 503034), currently in phase II clinical development for the treatment of chronic hepatitis C virus (HCV) infection.

The FDA granted fast track designation since the proposed first indication for SCH 503034 is for treatment of HCV in patients with HCV genotype 1 virus who have not responded to combination therapy with pegylated interferon and ribavirin, the current standard of care, thus representing an unmet medical need. Moreover, SCH 503034 is an orally active inhibitor of the hepatitis C virus serine protease that inhibits HCV replication. This mechanism is distinct from those of current therapies, thus SCH 503034 represents a novel class of HCV inhibitor, claims the Schering Plough.

SCH 503034 has demonstrated potent antiviral activity and was well- tolerated, both as monotherapy and in combination with Peg-Intron (peginterferon alfa-2b), in phase I clinical studies in patients chronically infected with HCV genotype 1 who were non-responders to previous therapy, including peginterferon and ribavirin combination therapy

Based on the results of the phase I clinical programme and extensive preclinical safety and pharmacology studies, Schering-Plough is conducting a large, randomised phase II dose-finding study involving 300 patients worldwide. This study evaluates the safety and efficacy of SCH 503034 in combination with Peg-Intron, with and without added ribavirin, for 24 or 48 weeks in patients with chronic HCV genotype 1 who were nonresponders to previous peginterferon and ribavirin combination therapy. The primary objective of this study is to determine the safe and effective dose range of SCH 503034 in combination with Peg-Intron in this patient population. A secondary objective is to explore whether or not ribavirin provides an additional benefit when combined with SCH 503034 plus Peg-Intron.

Peg-Intron is approved in the United States as monotherapy and for use in combination therapy with Rebetol (ribavirin, USP) for the treatment of chronic hepatitis C in patients with compensated liver disease who are at least 18 years of age, and is not approved for treatment of patients who are non-responders to previous therapy.