The co-existence of NS5A and NS5B resistance-associated substitutions is associated with virologic failure in Hepatitis C Virus genotype 1 patients treated with sofosbuvir and ledipasvir

Objective
The present study aimed to reveal the factors associated with virologic failure in sofosbuvir and ledipasvir (SOF/LDV)-treated patients, and identify baseline NS5A or NS5B resistance-associated substitutions (RASs).
Methods
Four hundred ninety-three patients with Hepatitis C Virus (HCV) genotype 1b infection were treated with SOF/LDV; 31 had a history of interferon (IFN)-free treatment with daclatasvir and asunaprevir. The effect of baseline RASs on the response to SOF/LDV therapy was analyzed.
Results
Overall, a sustained virologic response at 12 weeks (SVR12) was achieved in 476 patients (96.6%). The SVR12 rates in the patients with IFN-free treatment-naïve and retreatment were 97.6% and 80.6%, respectively. HCV elimination was not achieved in 17 patients, 11 (including 5 with IFN-free retreatment) of whom had virologic failure. Eight patients had coexisting NS5A RASs of Q24, L28 and/or R30, L31, or Y93 and one patient had coexisting NS5A RASs of P32L and A92K. Interestingly, 10 and 8 patients had NS5B A218S and C316N RAS respectively. According to a multivariate analysis, coexisting NS5A RASs, NS5A P32 RAS, NS5B A218 and/or C316 RASs, and γ-glutamyltranspeptidase were associated with virologic failure. In the naïve patients, all patients without NS5B A218 and/or C316 RAS achieved an SVR12. Notably, the SVR12 rates of patients with coexisting NS5A and NS5B RASs were significantly lower (83.3%).
Conclusions
Although SOF/LDV therapy resulted in a high SVR12 rate, coexisting NS5A and NS5B RASs were associated with virologic failure. These results might indicate that the coexisting baseline RASs influence the therapeutic effects of SOF/LDV.