Gilead Sciences announced topline results from four international Phase 3 clinical studies (ASTRAL-1, ASTRAL-2, ASTRAL-3 and ASTRAL-4) evaluating the once-daily, fixed-dose combination of sofosbuvir (SOF) with velpatasvir (VEL) for the treatment of genotype 1-6 chronic hepatitis C virus (HCV) infection.

The double-blind, placebo-controlled ASTRAL-1 study, and the open-label ASTRAL-2 and ASTRAL-3 studies included 1,035 patients with genotype 1-6 HCV infection who received SOF/VEL for 12 weeks. The ASTRAL-4 open-label study randomized 267 patients with decompensated cirrhosis (Child-Pugh class B) to receive 12 weeks of SOF/VEL with or without ribavirin (RBV), or 24 weeks of SOF/VEL. The primary endpoint for all studies was sustained virologic response at week 12 (SVR12).

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Results from the ASTRAL-1, ASTRAL-2 and ASTRAL-3 studies showed that among the 1,035 patients treated with SOF/VEL for 12 weeks, 98% achieved the primary efficacy endpoint of SVR12. ASTRAL-1 met its primary endpoint of statistical superiority to the pre-specified SVR12 goal of 85% (P<0.001). In ASTRAL-2, the SVR12 rate among genotype 2 HCV-infected patients receiving SOF/VEL for 12 weeks was statistically superior to the SVR12 rate for patients receiving SOF+RBV for 12 weeks (P=0.018). In ASTRAL-3, the SVR12 rate among genotype 3 HCV-infected patients receiving SOF/VEL for 12 weeks was statistically superior to that of patients treated with SOF+RBV for 24 weeks (P<0.001). In ASTRAL-4, patients with Child-Pugh class B cirrhosis receiving SOF/VEL+RBV achieved higher SVR12 rates than patients receiving SOF/VEL for 12 or 24 weeks. Among genotype 1 and 3 patients treated with SOF/VEL+RBV for 12 weeks, the SVR12 rates were 96% and 85%, respectively.

The SOF/VEL fixed-dose combination has been granted Breakthrough Therapy designation from the FDA.

Sofosbuvir is a nucleotide analog polymerase inhibitor and velpatasvir is an investigational pangenotypic NS5A inhibitor.

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