VX-135 (ALS-2200) is a uridine nucleotide analogue pro-drug that appears to have a high barrier to drug resistance based on in vitro studies. It is designed to inhibit the replication of the hepatitis C virus by acting on the NS5B polymerase. In vitro studies of the compound showed antiviral activity across all genotypes, or forms, of the hepatitis C virus, including genotypes more prevalent outside of the United States.Earlier this year, Vertex announced the first 7-day viral kinetic data for VX-135. Based on these data, the company plans to initiate multiple all-oral, phase II proof-of-concept studies, including a study of VX-135 and ribavirin and a study of VX-135 and telaprevir, the company's approved protease inhibitor marketed as INCIVEK for people with chronic genotype 1 hepatitis C. Vertex is on track to initiate the study of VX-135 in combination with ribavirin by the end of 2012, followed by the study with telaprevir in early 2013. The studies will evaluate safety, tolerability and viral cure rates of 12-week combination regimens in people with chronic non-cirrhotic genotype 1 hepatitis C who have not previously been treated (treatment-naïve). About Hepatitis C Hepatitis C is a blood-borne infectious disease of the liver and is a leading cause of chronic liver disease and liver transplants. The World Health Organization estimates that nearly 170 million people worldwide, approximately 3% of the world's population, are infected with hepatitis C virus (HCV). The CDC (Centers for Disease Control and Prevention) has reported that more than three million people in the United States are chronically infected with HCV. About Medivir Medivir is an emerging research-based pharmaceutical company focused on infectious diseases. Medivir has world class expertise in polymerase and protease drug targets and drug development which has resulted in a strong infectious disease R&D portfolio. The Company's key pipeline asset is simeprevir (TMC435), a novel protease inhibitor in phase III clinical development for hepatitis C that is being developed in collaboration with Janssen R&D Ireland.