Pharmasset Receives Notice of Allowance( -USPTO to grant patent covering the ...),Health

-USPTO to grant patent covering the anti-HCV drug PSI-6130 and its active

metabolites

PRINCETON, N.J., June 26 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) announced that the United States Patent and Trademark Office has issued a Notice of Allowance for patent application Serial No. 10/828,753 titled, "Modified Fluorinated Nucleoside Analogues," covering the composition of matter of a family of molecules invented at Pharmasset for the treatment of hepatitis C virus (HCV), including PSI-6130 and the active metabolite of PSI-7851. R7128, a prodrug of PSI-6130, a nucleoside analogue polymerase inhibitor of HCV, is being developed through Pharmasset's collaboration with Roche. PSI-7851 is a proprietary nucleotide analogue polymerase inhibitor of HCV that Pharmasset has nominated as a lead development candidate.

"We are pleased that the USPTO has recognized our intellectual property rights in our growing pipeline of HCV nucleoside polymerase inhibitors," stated Schaefer Price, Pharmasset's Chief Executive Officer. "The success that our in-house research team has had in discovering new HCV product candidates can now be translated into potentially significant commercial value."

About R7128

R7128 is being developed for the treatment of chronic HCV infection. R7128 is a prodrug of PSI-6130, a cytidine nucleoside analog inhibitor of HCV RNA polymerase. A prodrug is a chemically modified form of a molecule designed to enhance the absorption, distribution and metabolic properties of that molecule. Results from an oral single ascending dose study of PSI-6130 in 24 healthy male volunteers showed that PSI-6130 was generally well tolerated with no serious adverse events in doses up t
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