The US Food and Drug Administration (FDA) approved the first drug combination to treat the majority of people infected with chronic hepatitis C virus (HCV). Epclusa from Gilead Sciences of Foster City, California, is a single-tablet, fixed-dose combination of the previously approved Sovaldi (sofosbuvir), a nucleotide analog HCV NS5B polymerase inhibitor, and velpatasvir (GS-5816), a pan-genotypic HCV NS5A protein inhibitor. The agency gave the green light to Epclusa to treat people infected with all six genotypes of HCV without cirrhosis. The FDA based its decision on phase 3 ASTRAL studies in 1,035 subjects with genotype 1–6 chronic HCV infection, in which Epclusa produced a sustained virologic response lasting 12 weeks in 98% of individuals. The combination achieved high cure rates across all HCV genotypes, including genotypes 2 and 3, which traditionally have required ribavirin. Gilead said Epclusa's wholesale acquisition cost (WAC) will be $74,760 for a 12-week course. The big biotech markets Sovaldi at a WAC of $84,000 per 12-week course to treat HCV genotypes 1–4. Its other HCV combo therapy, Htarvoni (ledipasvir/sofosbuvir), costs $94,500 per course and is approved to treat HCV genotypes 1, 4, 5 and 6. For people with moderate to severe cirrhosis, the FDA approved Epclusa in combination with ribavirin. Epclusa's label includes a warning addressing the risk of bradycardia when Epclusa is used in combination with the antiarrhythmic drug amiodarone. The FDA had granted Epclusa a priority review and breakthrough therapy designation. The combination drug is Gilead's third Sovaldi-based product.