UPDATE 1-Pharmasset says HCV drugs show promise

* PSI-7977 shows rapid viral suppression

* PSI-938 found to be well tolerated

Jan 6 (Reuters) - Pharmasset Inc VRUS.O said interim analyses of clinical studies of its two drugs for chronic hepatitis C showed promise.

A mid-stage study of the drug, codenamed PSI-7977, showed rapid viral suppression with all patients remaining below limit of detection at the end of treatment. No serious adverse events were reported.

The drug was granted “fast track” designation in August. Fast-track status is designed to expedite the review of drugs to treat serious diseases and fill unmet medical needs. [id:nSGE67B0JZ]

The company said it expects to start a 24-week mid-stage study of the drug in the second quarter of 2011.

An early-stage study of the drug, codenamed PSI-938, as a monotherapy was found to be safe and well-tolerated, Pharmasset said.

The Princeton, New Jersey-based company’s shares, which have risen 50 percent in the last three months, closed at $46.59 on Wednesday on Nasdaq. (Reporting by Shravya Jain in Bangalore; Editing by Sriraj Kalluvila)