Pharmasset to Webcast an Investor Event from the AASLD Meeting

PRINCETON, N.J., Nov. 1 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) today announced that it will webcast an investor event from the American Association for the Study of Liver Diseases (AASLD) on Monday, November 2, 2009 starting at 7:00pm ET. During this webcast, management will review Pharmasset's progress on the programs that are the subject of presentations at AASLD.

To access a simultaneous webcast of this event via the internet, log on to the "Events & Presentations" section of the Investor Center on Pharmasset's website at http://investor.pharmasset.com/events.cfm . Please connect to the website at least ten minutes prior to the start of the presentation to ensure adequate time for a reliable connection and any software download that may be necessary for the webcast. The following abstracts are available on the AASLD website (AASLD.org).

PSI-7851

Late Breaker Abstract 17

"Antiviral Activity, Pharmacokinetics, Safety, and Tolerability of PSI-7851, a Novel Nucleotide Polymerase Inhibitor for HCV, Following Single and 3 Day Multiple Ascending Oral Doses in Healthy Volunteers and Patients with Chronic HCV Infection" will be presented in a late breaker poster session on Monday November 2nd at 8am ET. Authors of the study are M. Rodriguez-Torres; E. Lawitz; S. Flach; J. M. Denning; E. Albanis; W. Symonds; M. M. Berrey.

RG7128/INFORM-1

Abstract 1585

"Combination Therapy with Nucleoside Polymerase R7128 and Protease R7227/ITMN-191 Inhibitors in Genotype 1 HCV Infected Patients: Interim Resistance Analysis of INFORM-1 Cohorts" will be presented in a poster session on Tuesday November 3rd at 8am ET. Authors of the study are A-D S. Le Pogam; M. Chhabra; S. Ali; J. Yan; M.J. Ilnicka; H. Kang; J.M. Wong; A. Kosaka; A. Ewing; A. Seshaadri; A. De La Rosa; W.Z. Bradford; K.Klumpp; N. Shulman; P.F. Smith; N. Cammack; I. Najera.

Abstract 193

"Combination Therapy With A Nucleoside Polymerase (R7128) And Protease (R7227/ITMN-191) Inhibitors In HCV: Safety, Pharmacokinetics, And Virologic Results From INFORM-1." will be presented at the Presidential Plenary session on Tuesday November 3rd at 8am ET. Authors of the study are E.J. Gane; S.K. Roberts; C.A. Stedman; P.W. Angus; B. Ritchie; R. Elston; D. Ipe; P.N. Morcos; I. Najera; T. Chu; M.M. Berrey; W.Z. Bradford; M. Laughlin; N. Shulman; P.F. Smith.

Abstract 1594

"Pharmacokinetics/Pharmacodynamics (PK/PD) of Combination R7227 and R7128 Therapy From INFORM-1 Demonstrates Similar Early HCV Viral Dynamics When R7227 is Combined With Either PEG-IFN/Ribavirin (SOC) or R7128" will be presented in a poster session on Tuesday November 3rd at 8am ET. Authors of the study are P.N. Morcos; R. Kulkarni; D. Ipe; S. Jumbe; J. Tran; W.Z. Bradford; W. Symonds; W.Z. Bradford; E.J. Gane; S.K. Roberts; N. Shulman; P.F. Smith.

PSI-938

Abstract 1605

"Novel 2 -F-2 -C-Methylpurine Nucleotide Analogs Are Active Inhibitors of HCV Replication And Lack Cross-Resistance with Other Nucleos(t)ide Analogs" will be presented in a poster session on Tuesday November 3rd at 8am ET. Authors of the study are A.M. Lam; C.L. Espiritu; H. Micolochick Steuer; E. Murakami; C. Niu; M. Keilman; D.N. Frick; J.A. Heck; M.J. Sofia; D. Nagarathnam; W. Chang; P.G. Reddy; B.S. Ross; B. Chun; P. Wang; H. Zhang; S. Rachakonda; D. Bao; M.J. Otto; P.A. Furman.

About Pharmasset

Pharmasset is a clinical-stage pharmaceutical company committed to discovering, developing, and commercializing novel drugs to treat viral infections. Pharmasset's primary focus is on the development of oral therapeutics for the treatment of hepatitis C virus (HCV) and, secondarily, on the development of Racivir(TM) for the treatment of human immunodeficiency virus (HIV). Our research and development efforts focus on nucleoside/tide analogs, a class of compounds which act as alternative substrates for the viral polymerase thus inhibiting viral replication. We currently have three clinical-stage product candidates. RG7128, a nucleoside analog for chronic HCV infections, is in a Phase 2b clinical trial in combination with Pegasys(R) plus Copegus(R) and is also in INFORM studies, the first series of studies designed to assess the potential of combinations of small molecules without Pegasys(R) and Copegus(R) to treat chronic HCV. These clinical studies are being conducted through a strategic collaboration with Roche. Our other clinical stage candidates are PSI-7851, an unpartnered, next generation HCV nucleotide analog which has completed initial Phase 1 clinical studies, and Racivir, for the treatment of HIV, which has completed a Phase 2 clinical trial. We have also recently announced the nomination of two purine nucleotide analogs, PSI-938 and PSI-879, for preclinical development.

Pegasys(R) and Copegus(R) are registered trademarks of Roche.

Forward-Looking Statements

Pharmasset "Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: Statements in this press release regarding our business that are not historical facts are "forward-looking statements" that involve risks and uncertainties, including, without limitation, the risk that adverse events could cause the cessation or delay of any of the ongoing or planned clinical trials and/or our development of our product candidates, the risk that the results of previously conducted studies involving our product candidates will not be repeated or observed in ongoing or future studies involving our product candidates, the risk that our collaboration with Roche will not continue or will not be successful and the risk that any one or more of our product candidates will not be successfully developed and commercialized. For a discussion of these risks and uncertainties, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section of our Annual Report on Form 10-K for the fiscal year ended September 30, 2008 and our Quarterly Report on Form 10-Q for the period ended June 30, 2009 filed with the Securities and Exchange Commission entitled "Risk Factors" and discussions of potential risks and uncertainties in our subsequent filings with the Securities and Exchange Commission.

www.pharmasset.com

    Contact
    Richard E. T. Smith, Ph.D.
    VP, Investor Relations and Corporate Communications
    richard.smith@pharmasset.com
    Office: +1 (609) 613-4181

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