Pharmasset Inc. has started its Phase II clinical trial investigating the combination of its nucleotide polymerase inhibitor PSI-7977 and Bristol-Myers Squibb’s NS5A replication complex inhibitor BMS-790052 for the treatment of chronic hepatitis C virus (HCV) infection.

“We are happy to announce the initiation of this important combination trial,” stated William Symonds, a Pharmasset senior vice president, in a May 26 press release from the Princeton, New Jersey–based company. “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 [direct acting antivirals] 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.”

This Phase IIa trial is planned to enroll about 84 people with chronic HCV genotypes 1, 2 or 3 who have not been treated previously. The trial’s primary goal is to compare sustained virologic response (SVR)—virologic cure—rates between the six treatment groups testing different PSI-7977/BMS-790052 dosing schedules, both alone and in combination with the oral HCV treatment ribavirin. 

To learn more about the clinical trial, officially titled the “Study to Determine the Safety and Effectiveness of Antiviral Combination Therapy to Treat Hepatitis C Virus (HCV) Infected Patients Who Have Previously Not Been Treated With Standard of Care,” click here.