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PSI-7977 + BMS-790052 Trial for Hepatitis C

SUMMARY
Pharmasset announced the start of a Phase 2a study of an all-oral antiviral regimen of HCV polymerase inhibitor PSI-7977 plus NS5A replication complex inhibitor BMS-790052.

The advent of direct-acting antiviral agents that target different steps of the hepatitis C virus (HCV) lifecycle is expected to revolutionize chronic hepatitis C treatment.

The first 2 such drugs approved by the U.S. Food and Drug Administration -- the HCV protease inhibitors boceprevir (Victrelis) and telaprevir (Incivek) -- are indicated for use in combination with current standard therapy consisting of pegylated interferon plus ribavirin. But hepatitis C patients and clinicians are eagerly awaiting all-oral regimens that will avoid injected interferon and its difficult side effects.

Pharmasset, Inc. announced last week that it will test a variety of 24-week regimens of PSI-7977 plus Bristol-Myers Squibb's BMS-790052. As reported at this year's EASL meeting in April, PSI-7977 worked well both with standard therapy and in an all-oral regimen with PSI-938. A combination of BMS-790052 plus BMS-650032 produced high response rates in prior non-responders.

The new Phase 2a trial will enroll treatment-naive patients with both hard-to-treat HCV genotype 1 and genotypes 2 or 3. Some participants will have a 1-week PSI-7977 monotherapy lead-in period before adding BMS-790052. Other arms will start the 2 experimental drugs plus ribavirin at the same time.

Below is an edited excerpt from a recent Pharmasset press release describing the trial.

All-Oral Combination Study with PSI-7977 for
HCV Genotypes 1, 2 and 3 Initiated

Princeton, N.J. -- May 26, 2011 -- Pharmasset, Inc. (Nasdaq: VRUS) announced today the initiation of a Phase 2a trial investigating the combination of Pharmasset's PSI-7977, a nucleotide polymerase inhibitor, and BMS-790052, Bristol-Myers Squibb Company's (NYSE: BMY) NS5A replication complex inhibitor, for the treatment of chronic hepatitis C (HCV). This trial is the result of a clinical collaboration agreement between Pharmasset and Bristol-Myers Squibb announced in January 2011.

"We are happy to announce the initiation of this important combination trial," stated William Symonds, Pharmasset's Senior Vice President of Clinical Pharmacology and Translational Medicine. "Recent data from Bristol-Myers Squibb's combination study demonstrated that individuals with HCV can be cured without the traditional interferon and ribavirin, but only if two potent DAAs are used and drug resistance is avoided. We believe Pharmasset's nucleotide analogs have demonstrated potent antiviral activity and a high barrier to resistance and therefore have the potential to be the future backbone of interferon-free treatment."

About the Trial

This Phase 2a trial is planned to enroll approximately 84 patients with chronic HCV genotypes 1, 2 or 3 who have not been treated previously. The primary endpoint of the trial is sustained virologic response (SVR). The trial will be conducted in the U.S. Subjects will be randomized equally across each of the following arms:

PSI-7977 400mg QD for 7 days, then add BMS-790052 60mg QD for further 23 weeks in genotype 1 subjects;
PSI-7977 400mg QD for 7 days, then add BMS-790052 60mg QD for further 23 weeks in genotype 2 or 3 subjects;
PSI-7977 400mg QD and BMS-790052 60mg QD for 24 weeks in genotype 1 subjects;
PSI-7977 400mg QD and BMS-790052 60mg QD for 24 weeks in genotype 2 or 3 subjects;
PSI-7977 400mg QD, BMS-790052 60mg QD and ribavirin for 24 weeks in genotype 1 subjects;
PSI-7977 400mg QD, BMS-790052 60mg QD and ribavirin for 24 weeks in genotype 2 or 3 subjects.

Additional details can be found at www.clinicaltrials.gov.

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 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 three 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 third quarter 2011. Mericitabine (RG7128) continues in two Phase 2b trials and one interferon-free trial conducted through a strategic collaboration with Roche.

For more information, see www.pharmasset.com.

6/3/11

Source
Pharmasset, Inc. All-Oral Combination Study with PSI-7977 for HCV Genotypes 1, 2 and 3 Initiated. Press release. May 26, 2011.



 



 




 



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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