Abstract

IntroductionDaclatasvir is a non-structural protein 5A (NS5A) inhibitor with activity against hepatitis C virus (HCV) genotypes 1–6 in vitro, and asunaprevir is a non-structural protein 3 (NS3) protease inhibitor with activity against genotypes 1, 4, 5, and 6. This study evaluates potential options for the re-treatment of HCV genotype 1b-infected patients who have failed combination therapy with daclatasvir plus asunaprevir.MethodsThe antiviral activity of drug combination regimens in HCV subgenomic replicon cell lines representing genotype 1b (Con1 strain) wild-type or a variant with specific NS5A and NS3 amino acid substitutions conferring resistance to daclatasvir and asunaprevir were compared using replicon elimination assays. Drug concentrations representing multiple 50% effective concentrations (EC50) derived in vitro and trough plasma concentrations observed in a clinical setting were utilized.ResultsAt multiple EC50 values of each drug (3×, 10×, and 30× EC50), combinations of daclatasvir plus sofosbuvir, sofosbuvir plus ledipasvir, sofosbuvir plus simeprevir, and sofosbuvir plus either a next-generation NS3 or NS5A inhibitor demonstrated comparable activity in wild-type and daclatasvir/asunaprevir-resistant cell lines. At clinically relevant drug trough concentrations, combination regimens of daclatasvir plus asunaprevir plus beclabuvir (±ribavirin), and daclatasvir plus asunaprevir plus beclabuvir plus sofosbuvir efficiently cleared daclatasvir + asunaprevir-resistant replicons from cells within 5 days of treatment.ConclusionOur in vitro results highlight a number of potential all-oral treatment options for patients who do not achieve a sustained virologic response following therapy with daclatasvir plus asunaprevir. These results require further evaluation in clinical studies.Electronic supplementary materialThe online version of this article (doi:10.1007/s40121-014-0052-8) contains supplementary material, which is available to authorized users.

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