Gilead Sciences, a biopharmaceutical company based in Foster City, Calif., released 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-naïve 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% of patients achieving a sustained virologic response (SVR) in the sofosbuvir plus RBV treatment group versus 67% 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% 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.

In NEUTRINO, 327 treatment-naïve HCV genotype 1, 4, 5 and 6 patients were treated for 12 weeks with sofosbuvir 400mg once daily in combination with RBV (1,000mg or 1,200mg/day) and peg-IFN (180μg/week). This study met its primary efficacy endpoint of superiority compared to a predefined historic control SVR rate of 60% with 90% of patients achieving SVR12 after completing therapy (P

"These data support the favorable clinical profile of sofosbuvir as the backbone of a potent, safe and well-tolerated treatment regimen that is effective across a broad range of HCV patient genotypes," said Norbert Bischofberger, PhD, executive vice president of R&D and CSO, Gilead Sciences. "The sofosbuvir regimens in these trials allowed us to shorten the duration of effective hepatitis C therapy to just 12 weeks for treatment-naïve patients with genotypes 1 through 6."