PRINCETON, N.J., July 6, 2011 /PRNewswire/ -- Pharmasset, Inc. (NASDAQ: VRUS), announced today that it has entered into a clinical collaboration agreement with Tibotec Pharmaceuticals to evaluate in a Phase 2 study the safety and efficacy of PSI-7977, Pharmasset's investigational nucleotide polymerase inhibitor, in combination with TMC435, Tibotec Pharmaceuticals' investigational protease inhibitor, for the treatment of chronic hepatitis C virus (HCV).
This phase 2 proof of concept study will evaluate the potential to achieve sustained virologic response 12 weeks post treatment with an all oral, once-daily, interferon-free treatment regimen in patients infected with genotype 1 HCV. Specifically, the study will assess the safety, pharmacokinetics and pharmacodynamics of 12 and 24 weeks of PSI-7977 in combination with TMC435, with and without ribavirin, in patients chronically infected with HCV genotype 1 who had a prior null response to peginterferon alfa and ribavirin treatment. The study is planned to start in the second half of 2011.
"We are excited to be working with Tibotec to simplify and improve HCV treatment," stated Bill Symonds, PharmD, Pharmasset's Senior Vice President of Clinical Pharmacology and Translational Medicine. "PSI-7977 is now being studied in interferon-free combinations with each of the three leading classes of direct-acting antivirals: Tibotec's protease inhibitor, Bristol-Myers Squibb's NS5a inhibitor, and our own nucleotide, PSI-938. This advances one of our key goals at Pharmasset: to develop our nucleotide analogs as the backbone of interferon-free HCV therapy."
About PSI-7977
PSI-7977 is a prodrug of a uracil nucleotide analog polymerase inhibitor we are developing for the treatment of chronic HCV infection. PSI-7977 has completed a 28 day phase 2a trial in combination with peg-interferon and ribavirin (Peg-IFN/RBV) and is currently being tested in four phase 2b studies: the PROTON trial in combination with peg-IFN/RBV in HCV genotype 1, 2 or 3 patients; the ATOMIC trial with peg-IFN/RBV in HCV genotypes 1,4,5,6; the ELECTRON trial, an interferon sparing /interferon free study in HCV genotypes 1,2 and 3 and a study with Bristol-Myers Squibb's NS5a inhibitor, BMS-790052, as part of an interferon free regimen. Pharmasset also anticipates initiating its own interferon free trial with PSI-7977 and PSI-938, a guanine nucleotide polymerase inhibitor in the third calendar quarter 2011.
SOURCE Pharmasset, Inc.
