Results Reported at American Association for the Study of Liver Diseases (AASLD) Meeting SAN FRANCISCO, Nov. 14 /PRNewswire-FirstCall/ -- Schering-Plough's investigational oral hepatitis C protease inhibitor (SCH 503034) capsules demonstrated potent antiviral activity and was well-tolerated, both as monotherapy and in combination with PEG-INTRON(R) (peginterferon alfa-2b), in Phase I clinical studies in patients chronically infected with hepatitis C virus (HCV) genotype 1 who were nonresponders to previous therapy, including peginterferon combination therapy. HCV genotype 1 is the most common form of the virus worldwide and is considered the most difficult to treat successfully. Currently, there are no products approved for treating HCV patients who failed previous therapies, representing an area of great unmet medical need. Chronic hepatitis C affects more than 10 million people in major world markets and is the leading cause of chronic liver disease. The results of the studies were presented for the first time at the 56th Annual Meeting of the American Association for the Study of Liver Diseases (AASLD). "These early results are important because they show protease inhibitor SCH 503034 exhibits a potent and direct antiviral effect on HCV genotype 1," said Professor Stefan Zeuzem, M.D., Saarland University, Homburg, Germany, who presented the data. "This promising oral antiviral agent may point the way to future HCV treatment regimens that are more effective, less toxic and shorter in duration." SCH 503034 is an oral HCV NS3 protease inhibitor and one of the most advanced investigational agents in a potential new class of HCV drugs. The NS3 protease is part of the HCV replication complex and its activity is essential for viral replication. It has long been a key target for HCV drug development. In the Phase I studies, SCH 503034 capsules exhibited potent and rapid dose-related reductions in HCV viral load and ALT levels. Elevated ALT levels are considered to be a marker of liver injury due to HCV infection. In the combination study, SCH 503034 showed an additive effect to PEG-INTRON, with 4 of 10 patients in the SCH 503034 400 mg TID combination group achieving undetectable virus during the 14-day treatment vs. 0 of 22 patients receiving PEG-INTRON alone. Based on the results of the Phase I program, Schering-Plough has initiated a large, Phase II study of SCH 503034 in combination with PEG-INTRON in nonresponders with HCV genotype 1. "As a leader in the development of novel hepatitis therapies for more than decade, Schering-Plough is uniquely positioned to develop innovative products and improved treatment regimens for HCV infection," said Robert J. Spiegel, M.D., chief medical officer and senior vice president of medical affairs, Schering-Plough Research Institute. "The development of SCH 503034, as well as our ongoing research with PEG-INTRON, underscores our long-term commitment to this therapeutic area and to finding better therapies to benefit patients with hepatitis C infection." Phase I Studies and Results In the Phase I rising multiple dose monotherapy study, 61 patients (45 active, 16 placebo) with HCV genotype 1 who failed previous peginterferon- based therapy (