Eight weeks of Gilead Sciences’ Sovaldi and GS-5816, with or without ribavirin, cured high rates of people with genotype 3 of hepatitis C virus (HCV), but yielded unsatisfactory results among those with genotypes 1 and 2, MedPage Today reports. Researchers in a pair of studies with identical designs randomly divided 120 people with genotype 1, 103 people with genotype 2, and 102 people with genotype 3 into one of four groups: Everyone received Sovaldi, plus either 25 milligrams or 100 mg of the investigational NS5A inhibitor known as GS-5816, with or without ribavirin. They were all treated for eight weeks. Results were presented at the Annual Meeting of the American Association for the Study of Liver Diseases in Boston.

Among those with genotype 1, 83 percent of the participants who took 25 mg of GS-5816 plus ribavirin achieved a sustained virologic response 12 weeks after completing therapy (SVR12, considered a cure), compared with 81 percent of those who took 100 mg with ribavirin. In the arms that did not receive ribavirin, 87 percent of those who took 25 mg of GS-5816 were cured, compared with 90 percent of those who took 100 mg.

Among those with genotype 2 who did not take ribavirin, a respective 77 percent and 88 percent of the low and high doses of GS-5816 were cured. As for the genotype 2s who did take ribavirin, 88 percent of both those on the high and the low dose of GS-5816 achieved an SVR12.

Among those with genotype 3 who did not take ribavirin, a respective 100 percent and 96 percent of those in the low- and high-dose arms were cured. (One person in the high-dose arm withdrew consent to be in the study, which is why that cure rate wasn’t 100 percent.) As for the genotype 3s who did take ribavirin, 88 percent of those taking the low dose and 100 percent of those on the high dose were cured.

Adverse side effects among those with genotypes 1 and 2 were mostly mild to moderate. There were four serious adverse side effects.

The adverse side effects for those with genotype 3 were mostly mild. There were two grade 3 or 4 side effects.

To read the MedPage Today story, click here.