Pharmasset's PSI-7977 is one of the hottest drugs now in development for hepatitis C. And the biotech burnished its rep this morning by restructuring its clinical program for the treatment, adding one arm which will study the drug as a single treatment and another arm which will pair it with ribavirin. Pharmasset ($VRUS), which saw its shares spike this morning on the news, modified a previously revealed arm for a group who will remain interferon-free for 12 weeks. Any newly approved drug that can offer patients an interferon-free approach to therapy is likely to quickly grab a significant market share in the blockbuster arena. "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 company said in a release. Story