Pharmasset Spiking 25%

Pharmasset, Inc. VRUS shares are soaring this morning, gaining more than 25% after the company announced it would be expanding its hepatitis C study, suggesting that the drug works. The drug, known as PSI-7977, is used for treating hepatitis C, and the company said that it is adding new groups of patients to the study. The company said it was adding new patients because PSI-7977 can quickly and consistently reduce virus levels and few patients become resistant to it. The Princeton, N.J.-based company will add 30 new patients to the study.