Successful retreatment of chronic HCV genotype-1 infection with ledipasvir and sofosbuvir after initial short course therapy with direct-acting antiviral regimens

Background. The optimal retreatment strategy for chronic hepatitis C virus (HCV) patients who fail directly-acting antiviral agent (DAA)-based treatment is unknown. In this study, we assessed the efficacy and safety of ledipasvir (LDV) and sofosbuvir (SOF) for 12 weeks in HCV genotype-1 (GT-1) patients who failed LDV/SOF-containing therapy. Methods. In this single-center, open-label, phase 2a trial, 34 participants with HCV (GT-1) and early-stage liver fibrosis who previously failed 4-6 weeks of LDV/SOF with GS-9669 and/or GS-9451 received LDV/SOF for 12 weeks. The primary endpoint was HCV viral load below the lower limit of quantification 12 weeks after completion of therapy (sustained virological response [SVR]₁₂). Deep sequencing of the NS3, NS5A, and NS5B regions were performed at baseline, at initial relapse, prior to retreatment, and at second relapse with Illumina next-generation sequencing technology. Results. Thirty-two of 34 enrolled participants completed therapy. Two patients withdrew after day 0. Participants were predominantly male and black, with median baseline HCV viral load of 1.3 × 10⁶ IU/mL and Metavir fibrosis stage 1 and genotype-1a. Median time from relapse to retreatment was 22 weeks. Prior to retreatment, 29 patients (85%) had NS5A-resistant variants. The SVR₁₂ rate was 91% (31/34; intention to treat, ITT) after retreatment. One patient relapsed. Conclusions. In patients who previously failed short-course combination DAA therapy, we demonstrate a high SVR rate in response to 12 weeks of LDV/SOF, even for patients with NS5A resistance-associated variants.