Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced results from two different investigational studies conducted to better understand the potential use of VICTRELIS™ (boceprevir), the company’s oral HCV NS3/4A protease inhibitor, in treating patients coinfected with chronic hepatitis C virus (HCV) and HIV-1. These data are being presented for the first time today at the 19 th Conference on Retroviruses and Opportunistic Infections (CROI) in Seattle. Results were presented from a 12-week post treatment interim analysis of a Phase IIb clinical study evaluating the investigational use of VICTRELIS in combination with peginterferon alfa-2b and ribavirin for the treatment of chronic HCV genotype 1 infection in adult patients coinfected with HIV-1 (n=100). In the study, a higher percentage of patients receiving VICTRELIS in combination with peginterferon alfa-2b and ribavirin had undetectable hepatitis C virus (HCV-RNA) 12 weeks after treatment ended (sustained virologic response-12 1 or SVR-12) than patients receiving peginterferon alfa-2b and ribavirin alone. Additionally, Merck announced results as part of a late-breaker poster session [Poster #771] from a pharmacokinetic study evaluating drug interactions between VICTRELIS and ritonavir-boosted HIV protease inhibitors in 39 healthy volunteers. In this study, concomitant administration of VICTRELIS with ritonavir (Norvir ®) in combination with atazanavir (Reyataz ®) or darunavir (Prezista ®), or with lopinavir/ritonavir (Kaletra ®) resulted in reduced exposures of the HIV medicines and VICTRELIS. These drug interactions may be clinically significant for patients infected with both chronic HCV and HIV by potentially reducing the effectiveness of these medicines when co-administered. Merck does not recommend the co-administration of VICTRELIS and ritonavir-boosted HIV protease inhibitors. "In light of the differing results in these data sets, Merck recognizes it is important to continue to study VICTRELIS in combination therapy in this difficult-to-treat patient population," said Eliav Barr, M.D., vice president, Project Leadership and Management, Infectious Diseases, Merck Research Laboratories. "Our collaborative studies with the French National Agency for Research on AIDS and Viral Hepatitis 2 (ANRS) and the AIDS Clinical Trial Group (ACTG), which is funded by the U.S. National Institute of Allergy and Infectious Diseases, will provide greater insight into the potential role of VICTRELIS in treating patients with chronic HCV genotype 1 infection who are coinfected with HIV-1." Indications and usage for VICTRELIS VICTRELIS is indicated for the treatment of chronic hepatitis C virus (HCV) genotype 1 (G1) infection, in combination with peginterferon alfa and ribavirin (P/R), in adult patients (18 years and older) with compensated liver disease, including cirrhosis, who are previously untreated or who have failed previous interferon and ribavirin therapy.