Pharmasset adds two treatment arms to PSI-7977 ELECTRON trial on HCV

Pharmasset, Inc. (Nasdaq: VRUS) announced today the addition of two treatment arms to the ELECTRON trial of PSI-7977, a nucleotide analog polymerase inhibitor, for the treatment of chronic hepatitis C (HCV). The rapid and consistent antiviral effects and high barrier to resistance demonstrated with PSI-7977 to date provided the rationale for additional exploratory regimens in this setting.  The protocol amendment adds one arm exploring 12 weeks of PSI-7977 monotherapy in treatment naive patients with HCV genotype 1 (GT1), and one arm of PSI-7977 and ribavirin (RBV) in treatment-experienced patients with HCV genotype 2 (GT2) or genotype 3 (GT3).  In addition, the previously announced arm in HCV GT1 patients with a prior "null" response to an interferon (IFN) containing regimen, which was planned to assess PSI-7977/IFN/RBV, has been modified to an IFN-free 12-week regimen of PSI-7977/RBV.

"We look forward to reporting SVR12 results from Part 1 and interim data from the PSI-7977 monotherapy arm of ELECTRON on Sunday, November 6th, 2011 at the upcoming 2011 American Association for the Study of Liver Diseases (AASLD) annual meeting.  The preliminary results to be discussed at AASLD led us to expand the study to add an arm of PSI-7977 monotherapy for HCV GT1," said Michelle Berrey, MD, MPH, Pharmasset's Chief Medical Officer.  "We and others continue to explore the potential of PSI-7977 for IFN-free and monotherapy treatment regimens in a broader group of individuals living with HCV of all genotypes and regardless of their response to prior treatment."

In addition to previously announced interferon-free studies of PSI-7977 by Bristol Myers Squibb and Tibotec, The National Institute of Health (NIH) recently initiated an interferon-free 24 week study of PSI-7977 400mg QD with and without ribavirin, in 60 treatment naive patients with HCV genotype 1 (GT1) in the US.