Gilead’s sofosbuvir for hepatitis C meets primary endpoint in fourth pivotal Phase 3 study

Gilead Sciences (Nasdaq:GILD) today announced topline results from the Phase 3 FUSION study evaluating 12- and 16-week courses of therapy with the once-daily nucleotide sofosbuvir plus ribavirin (RBV) in treatment-experienced patients with genotype 2 or 3 chronic hepatitis C virus (HCV) infection who failed prior treatment. The study met its primary efficacy endpoint of superiority compared to a predefined historic control sustained virologic response (SVR) rate of 25 percent. In FUSION, 50 percent of patients (n=50/100) in the 12-week arm and 73 percent of patients (n=69/95) in the 16-week arm achieved SVR12 (p<0.001 for both arms).

“This study demonstrates that all-oral therapy with sofosbuvir provides significant efficacy among difficult-to-treat hepatitis C patients who could not be cured by prior regimens containing pegylated interferon and now have limited treatment options,” said Norbert Bischofberger, PhD, Executive Vice President of Research and Development and Chief Scientific Officer. “With positive results from all four Phase 3 trials now in hand, Gilead is on track to meet its goal of filing regulatory applications in the United States and Europe in the second quarter.”

In the FUSION study, HCV genotype 2 or 3 patients who failed prior interferon-based therapy were randomized (1:1) to receive either a 12-week (n=103) or 16-week (n=98) course of sofosbuvir 400 mg once daily plus RBV (1,000 or 1,200 mg/day). Sixty-three percent of patients were infected with genotype 3. In the 12-week arm, SVR12 rates were 86 percent among genotype 2 and 30 percent among genotype 3 patients. In the 16-week arm, SVR12 rates were 94 percent among genotype 2 and 62 percent among genotype 3 patients. Among the 34 percent of FUSION participants who had compensated cirrhosis at baseline, 31 percent achieved SVR12 in the 12-week arm, and 66 percent achieved SVR12 in the 16-week arm. All patients in the study became HCV negative on treatment, and relapse accounted for all virologic failures.

No patients discontinued sofosbuvir or RBV due to adverse events. The most common adverse events reported in ≥15 percent of patients in the study were fatigue, headache, insomnia and nausea.

Results from all four pivotal Phase 3 studies of sofosbuvir – FUSION, POSITRON, FISSION and NEUTRINO – will support the initial regulatory filing for sofosbuvir as part of all-oral therapy with RBV among genotype 2 and 3 treatment-naïve, treatment-experienced and interferon-intolerant HCV patients, and for sofosbuvir in combination with RBV and pegylated interferon among treatment-naïve patients with genotypes 1, 4, 5 and 6.

Full results from these studies will be presented at a future scientific conference. Additional information about these and other ongoing clinical studies of sofosbuvir can be found at www.clinicaltrials.gov. Sofosbuvir is an investigational product and its safety and efficacy have not yet been established.