Pharmasset has begun screening in a phase IIb, international study of PSI-7977 and PSI-938, two nucleotide analog polymerase inhibitors for the treatment of chronic hepatitis C (HCV). The QUANTUM trial will evaluate interferon-free regimens of PSI-7977 400mg QD and PSI-938 300mg QD with and without ribavirin over 12 or 24 weeks in patients with HCV who have not been treated previously. The trial will also evaluate the use of PSI-938 monotherapy.

"The QUANTUM trial is the first interferon-free, all-nucleotide study with an SVR endpoint. The ability to include all HCV genotypes was supported by data from the NUCLEAR study and the interferon free arms of the ELECTRON trial. Data from ELECTRON are expected later this year,” stated Michelle Berrey, MD, MPH, Pharmasset's chief medical officer.