Pharmasset has announced the initiation of a Phase IIb clinical trial of PSI-7977, its nucleotide analogue polymerase inhibitor for the treatment of chronic hepatitis C (HCV) genotypes 1, 2 and 3.

The trial will evaluate PSI-7977 200mg QD and 400mg QD along with pegylated interferon alfa 2a and ribavirin, the current standard of care for patients with HCV genotype 1, who have not received previous treatment.

The trial will enrol approximately 125 patients with HCV genotype 1 and will be conducted in the US.

The primary endpoint will be the safety and tolerability of PSI-7977 in combination with the current standard of care over 12 weeks with response-guided therapy, permitting discontinuation of the current standard of care at week 24.

Pharmasset plans to report the interim data of the trial in the first half of 2011.