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HCV Polymerase Inhibitor PSI-938 Gets Fast Track Status

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The U.S. Food and Drug Administration (FDA) last week granted a "fast track" designation for PSI-938, an investigational nucleotide analog hepatitis C virus (HCV) polymerase inhibitor being developed by Pharmasset.

Studies have shown that PSI-938 has good antiviral activity and is generally well-tolerated. At this year's European Association for the Study of the Liver meeting (EASL 2011) researchers reported that more than 90% of patients treated with PSI-938 plus another polymerase inhibitor, PSI-7977, had undetectable HCV viral load after 14 days.

Below is an edited excerpt from a press release issued by Pharmasset announcing the FDA decision.

PSI-938 Receives Fast Track Designation from the FDA for the Treatment of Chronic Hepatitis C Infection

Princeton, N.J. -- August 24, 2011-- Pharmasset, Inc. (Nasdaq: VRUS) has received fast track designation from the U.S. Food and Drug Administration (FDA) for PSI-938 for the treatment of chronic hepatitis C virus (HCV) infection. PSI-938 is an oral guanosine nucleotide analog polymerase inhibitor of HCV.

In March 2011, Pharmasset presented data from the NUCLEAR study demonstrating that PSI-938 has potent antiviral activity and is generally safe and well tolerated, both as monotherapy and in combination with Pharmasset's lead nucleotide analog, PSI-7977. The NUCLEAR study was conducted in treatment naive subjects with genotype 1 HCV who were treated for 14 days with either PSI-938 or a combination of PSI-938 and PSI-7977 with 92% achieving HCV RNA <15 IU/mL, the limit of detection, in the combination arms. Pharmasset plans to initiate QUANTUM, an interferon-free combination trial with PSI-938 and PSI-7977 in the third quarter of 2011.  

Under the FDA Modernization Act of 1997, fast track designation may facilitate the development and expedite the review of a drug candidate that is intended for the treatment of a serious and life-threatening condition and demonstrates the potential to address an unmet medical need for such a condition. PSI-938 was granted the fast track designation primarily due to the need for HCV treatments with improved tolerability, safety and efficacy over the existing standard of care for both treatment-naive and treatment-experienced patients.

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 the development of oral therapeutics for the treatment of hepatitis C virus (HCV) infection. Our research and development efforts are focused 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 advancing in trials in various populations.

Our pyrimidine, PSI-7977, an unpartnered uracil nucleotide analog, is currently under study in four Phase 2b trials in patients with HCV genotypes 1 through 6, including abbreviated duration interferon and interferon-free regimens. Our purine, PSI-938, an unpartnered guanosine nucleotide analog, recently reported safety and efficacy data from 14 days of monotherapy as well as 14 days in combination with the pyrimidine, PSI-7977. An SVR-endpoint study of the purine-pyrimidine combination is anticipated to begin in the third quarter of 2011. Mericitabine (RG7128) continues in three Phase 2b trials and one interferon-free trial being conducted through a strategic collaboration with Roche.

For further information, see http://www.pharmasset.com.

8/30/11

Source

Pharmasset, Inc. PSI-938 Receives Fast Track Designation from the FDA for the Treatment of Chronic Hepatitis C Infection. Press release. August 24, 2011.