Positive results from two Ph III Studies of Gilead's sofosbuvir for hepatitis C

US biotech firm Gilead Sciences (Nasdaq: GILD) has revealed positive top-line results from two Phase III studies, FISSION and NEUTRINO, evaluating a 12-week course of the once-daily nucleotide sofosbuvir in combination with ribavirin (FISSION) and in combination with ribavirin and pegylated interferon (NEUTRINO) among treatment-naive patients with chronic hepatitis C virus (HCV) infection.

In the FISSION study, patients with genotype 2 or 3 HCV infection were randomized to receive either a 12-week course of sofosbuvir plus ribavirin (RBV) or standard of care with 24 weeks of pegylated interferon alfa-2a (peg-IFN) plus RBV. The study met its primary efficacy endpoint of non-inferiority of sofosbuvir plus RBV to peg-IFN plus RBV, with 67% (170/253) of patients achieving a sustained virologic response (SVR) in the sofosbuvir plus RBV treatment group versus 67% (162/243) in the peg-IFN plus RBV treatment group (95% CI for the difference: -7.5 to +8.0% for sofosbuvir plus RBV versus peg-IFN plus RBV; predefined criterion for non-inferiority was a lower bound of a two sided 95 percent CI of -15%).

All common adverse events (=10% in any group) occurred more frequently in subjects receiving peg-IFN and RBV as compared to sofosbuvir and RBV. The most common adverse events in the sofosbuvir plus RBV arm occurring in =10% of the patients were fatigue, headache, nausea, insomnia and dizziness.