Pharmasset Announces Issuance of U.S. Patent for PSI-7977

Pharmasset, Inc. VRUS announces that the United States Patent and Trademark Office has issued U.S. patent 7,964,580 ("the '580 patent") titled "Nucleoside Phosphoramidate Prodrugs". This patent generally relates to the composition of matter of PSI-7977 and its diastereomeric mixture for the treatment of hepatitis C virus. PSI-7977, a uracil nucleotide analogue polymerase inhibitor of HCV, is being studied in multiple phase 2 trials. "Today's announcement is a credit to our in-house research team in discovering new HCV product candidates," stated Schaefer Price, Pharmasset's President and Chief Executive Officer. "As the '580 patent is not due to expire until 2029, not including any patent term extension, it should become an important part of a growing portfolio of issued patents covering PSI-7977."