We are investigating small molecule approaches to treating chronic hepatitis C virus (HCV) infection. The NS3/4A protease inhibitor, RG7227/ITMN-191, is currently in Phase 2b clinical development in combination with Pegasys® (pegylated interferon alfa-2a) and Copegus® (ribavirin). A previous 14-day triple combination study demonstrated that treatment with RG7227/ITMN-191 led to rapid and sustained viral load reduction and that the compound was safe and well tolerated in the 14-day study. The protease inhibitor also is being evaluated in all-oral, twice-daily regimens in HCV patients in the INFORM-1 study. INFORM-1 is the first clinical trial to combine two direct-acting antiviral compounds -- RG7227/IMTN-191 and nucleoside polymerase inhibitor RG7128 (Roche/Pharmasset) -- in the absence of interferon or ribavirin. In October 2006, Roche and InterMune announced an exclusive worldwide collaboration to develop and commercialize products from InterMune's HCV protease inhibitor program, including RG7227/ITMN-191.