VX-135 Phase 2 TrialsVertex recently announced that it has entered into two non-exclusive agreements to conduct Phase 2 proof-of-concept studies of VX-135 in combination with simeprevir (TMC435), a protease inhibitor being jointly developed by Janssen R&D Ireland and Medivir AB, and with GSK2336805, an NS5A inhibitor in development by GlaxoSmithKline (GSK). The studies with GSK2336805 and simeprevir are expected to begin in early 2013, pending discussions with regulatory authorities. Screening is expected to begin in the coming weeks for a Phase 2 study of VX-135 and ribavirin. Vertex also plans to begin a study of VX-135 and telaprevir, the company's approved protease inhibitor marketed as INCIVEK ® (telaprevir) tablets for people with chronic genotype 1 hepatitis C, in early 2013, pending discussions with regulatory authorities. All of these Phase 2 studies will evaluate safety, tolerability and viral cure rates (SVR12; undetectable hepatitis C virus 12 weeks after the end of treatment) using 12-week combination regimens. About VX-135 (ALS-2200) 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. Vertex gained worldwide rights to ALS-2200 through an exclusive worldwide licensing agreement signed with Alios BioPharma, Inc. in June 2011. The agreement also includes a research program that focuses on the discovery of additional nucleotide analogues that act on hepatitis C polymerase. Vertex has the option to select additional compounds for development emerging from the research program. About INCIVEK INCIVEK ® (telaprevir) tablets is an oral medicine that acts directly on the hepatitis C virus protease, an enzyme essential for viral replication. INCIVEK has been prescribed to more than 50,000 patients in the United States. Approximately three out of four U.S. patients who are prescribed a direct-acting antiviral for the treatment of genotype 1 chronic hepatitis C (HCV) receive INCIVEK combination therapy. In Phase 3 clinical studies, 79 percent of people who had not previously been treated for HCV achieved a viral cure following treatment with INCIVEK combination therapy, compared with 46 percent of those who received pegylated-interferon and ribavirin (P/R) alone. Among people who were treated previously but did not achieve a viral cure, in the Phase 3 studies: 86 percent of relapsers achieved a viral cure with INCIVEK combination therapy compared to 22 percent with P/R alone; 59 percent of partial responders achieved a viral cure compared with 15 percent with P/R alone; and 32 percent of null responders achieved a viral cure compared with 5 percent with P/R alone. In addition, many people are eligible to complete treatment with INCIVEK combination therapy in 24 weeks – half the time required for P/R alone.