Evolution and persistence of resistance‐associated substitutions of hepatitis C virus after direct‐acting antiviral treatment failures

Abstract

Daclatasvir plus asunaprevir (DCV+ASV) treatment is an all-oral direct-acting antiviral (DAA) therapy for the genotype 1b HCV-infected patients. In this study, we investigated how resistance-associated substitutions (RASs) evolved after treatment failures and assessed the effect of those substitutions on viral fitness. Sequencing of NS5A and NS3 revealed typical RASs after treatment failures. Interestingly, the RASs of NS3 reverted to the wild-type amino acid within 1 year after treatment failures. However, the RASs of NS5A were stable and did not change. The effect of NS5A and NS3 RASs on viral RNA replication was assessed after mutagenic substitution in the genotype 1b HCV RNA. Among single substitutions, the effect of D168V was more substantial than the others and the effect of the triple mutant combination (D168V+L31V+Y93H) was the most severe. The RAS at NS5A Y93 affected both viral RNA replication and virus production. Finally, the effect of trans-complementation of NS5A was demonstrated in our co-transfection experiments and these results suggest that such a trans-complementation effect of NS5A may help maintain the NS5A RASs for a long time even after cessation of the DAA treatment. In conclusion, the results from this investigation would help understand the emergence and persistence of RASs.

Features of resistance-associated substitutions after failure of multiple direct-acting antiviral regimens for hepatitis C

“…NS3-RASs are known to disappear early because of low fitness, in contrast to NS5A-RASs, which are known to persist for longer. 20,28 The differences in each patient's clinical background in each regimen group may also contribute selection bias in the choice of treatment regimen by the attending physicians. The numbers of patients with multiple regimen failures in the present cohort was limited, possibly because of the improved efficacy of first-line DAA regimens.…”

Status of Direct-Acting Antiviral Therapy for Hepatitis C Virus Infection and Remaining Challenges

“…Management of patients after failure of a regimen that contains an NS5A inhibitor is a challenge, because NS5A inhibitors are part of all treatment regimens, and the RAS that arise in NS5A tend to persist and can increase replication fitness 87,88 . However, 96% of patients retreated with all 3 classes of DAAs in a single tablet (voxilaprevir, velpatasvir, and sofosbuvir) achieve an SVR (100% of patients with subtype 1b infection, 96% of patients with subtype 1a infection, 95% of patients with type 3 infections, and 91% of patients with type 4 infections) 86 .…”

Management and Treatment of Hepatitis C: Are There Still Unsolved Problems and Unique Populations?

“…Of note, NS5A RASs prior to therapy had a negative impact on virological response, leading to lower SVR rates (76% vs. 97% among treatment-experienced genotype 1a patients) [82]. On the contrary, NS5B protein's RASs limiting the efficacy of drugs such as SOF are harder to detect, as these variants typically replicate very poorly [83].…”