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People with hepatitis C virus (HCV) infection other than genotype 1 represent a heterogeneous group. The aim of the phase 2 C-SCAPE study was to evaluate elbasvir/grazoprevir (EBR/GZR), with or without ribavirin (RBV), in participants with HCV genotype 2, 4, 5 or 6 infection. This was a part randomised, open-label, parallel-group study (NCT01932762; PN047-03) of treatment-naive, noncirrhotic participants. Participants with HCV genotype 2 infection received GZR 100 mg + RBV ± EBR 50 mg for 12 weeks and those with genotype 4, 5 or 6 infection were randomized to receive EBR/GZR ± RBV for 12 weeks. The primary endpoint was sustained virological response 12 weeks after completion of treatment (SVR12; HCV RNA <25 IU/mL). Among participants with genotype 2 infection, SVR12 was achieved by 80% (24/30) of those receiving EBR/GZR + RBV and 73% (19/26) of those receiving GZR + RBV. SVR rates were high in participants with HCV genotype 4 infection receiving EBR/GZR with and without RBV (100% [10/10] and 90% [9/10]; respectively). In contrast, the addition of RBV to EBR/GZR appeared to increase SVR12 in participants with genotype 5 infection (EBR/GZR, 25%; EBR/GZR + RBV 100% [4/4]). In participants with genotype 6 infection, SVR12 was 75% (3/4) in both those receiving EBR/GZR and those receiving EBR/GZR + RBV. The safety profile was similar across treatment arms, with adverse events tending to occur more frequently among participants receiving RBV. In conclusion, these data support the inclusion of participants with genotype 4 or 6 infection in the EBR/GZR phase 3 studies. EBR/GZR ± RBV was unsatisfactory for participants with genotype 2 or 5 infection., (© 2017 John Wiley & Sons Ltd.)

Elbasvir (EBR; HCV NS5A inhibitor) and grazoprevir (GZR; HCV NS3/4A protease inhibitor) are approved as a fixed-dose combination to treat patients chronically infected with HCV genotypes 1 and 4. During the development programme and supported by in vitro potency, the efficacy of EBR+GZR was assessed in HCV GT3-infected patients. This study's aim was to determine the efficacy and tolerability of 12 or 18 weeks of EBR+GZR with ribavirin (RBV) in treatment-naïve, noncirrhotic HCV GT3-infected patients. Randomized patients received open-label EBR (50 mg once daily) + GZR (100 mg once daily) + RBV. The primary efficacy objective was to evaluate the sustained virologic response rates 12 weeks after the end of all study therapy (SVR12). SVR12 rates (95% confidence interval) were 45.0% (23.1, 68.5) and 57.1% (34.0, 78.2) after treatment with EBR+GZR+RBV for 12 weeks or 18 weeks, respectively. On-treatment virologic failure was observed in 41% (17 of 41) of patients. At virologic failure, resistance-associated substitutions (RASs) with a >five-fold shift in potency occurred in the NS3 region in six (35%) patients and in the NS5A region in 16 (94%) patients. The most common RAS at virologic failure was Y93H in NS5A which was identified in 13 of 17 (76%) patients. The efficacy of EBR+GZR+RBV was suboptimal in HCV GT3-infected patients due to a high rate of on-treatment virologic failure and treatment-emergent RASs which demonstrates an inadequate barrier to the development of GT3 resistance. However, rapid viral clearance demonstrated the antiviral activity of EBR+GZR+RBV in GT3-infected patients.clinicaltrials.gov: NCT01717326., (© 2017 John Wiley & Sons Ltd.)

Grazoprevir (GZR) is a second-generation hepatitis C virus NS3/4A protease inhibitor. The aim of this study was to evaluate GZR plus ribavirin (RBV) in patients with HCV GT1 infection. Noncirrhotic, IL28B CC patients with HCV genotype 1 infection were randomized to GZR 100 mg once daily and RBV for 12 or 24 weeks. Patients in the 12-week arm with detectable HCV RNA at treatment week 4 (TW4) had treatment extended to 24 weeks (response-guided therapy, RGT). The primary endpoint was sustained virologic response (SVR12) at follow-up week 12 (HCV RNA <25 IU/mL) in the per-protocol (PP) population (excluding patients with important protocol deviations). Twenty-six patients were randomized and 22 were included in the PP population. SVR12 was 58.3% (7 of 12) and 90% (9 of 10) in the RGT and 24-week arms, respectively. Seven PP patients had virologic failure, including one patient in the 24-week arm who relapsed after follow-up week 12. All three breakthrough patients had wild-type (WT) virus at baseline and developed breakthrough at TW6 or TW12 with Y56H, A156T and D168A/N mutations. Of the five relapse patients, four had WT at baseline (at relapse three had WT and one had V55A and D168A), and one had S122A/T at baseline and S122T at relapse. There were no serious adverse events (AEs), discontinuations due to AEs or grade 3/4 elevations in total and/or direct bilirubin. Grazoprevir plus RBV was associated with a rapid and sustained suppression of HCV RNA. These results support further evaluation of grazoprevir-based regimens (NCT01716156; protocol P039)., (© 2016 John Wiley & Sons Ltd.)

Unlabelled: Grazoprevir (MK-5172, Merck & Co., Inc.) is a selective inhibitor of the hepatitis C virus (HCV) NS3/4a protease. The aim of this study was to evaluate the safety and efficacy of grazoprevir at doses of 25-100 mg/day in combination with peginterferon and ribavirin (PEG-IFN/RBV). In this randomized, dose-ranging, multicentre trial, treatment-naive adults with chronic HCV genotype 1 infection received once-daily grazoprevir 25 mg, 50 mg or 100 mg plus PEG-IFN/RBV for 12 weeks. Patients with quantifiable HCV RNA (≥25 IU/mL) at week 4 received an additional 12 weeks of PEG-IFN/RBV. The primary endpoint was sustained virologic response (HCV RNA <25 IU/mL 12 weeks after completing therapy [SVR12]). Eighty-seven patients were randomly assigned and received ≥1 dose of therapy. Median time to undetectable HCV RNA was 16 days in the 100-mg arm and 22 days in the 25- and 50-mg arms. All patients except one had HCV RNA undetectable or unquantifiable at week 4 and received 12 weeks of therapy. SVR12 was achieved by 13 of 24 (54.2%), 21 of 25 (84.0%) and 23 of 26 (88.5%) patients in the 25-, 50- and 100-mg arms, respectively (per-protocol analysis). Three patients discontinued as a result of nonserious adverse events (AEs) and three patients experienced serious AEs. Transaminase elevations occurred in two patients (one each in the 25- and 100-mg arms)., Conclusion: These data support further study of the grazoprevir 100-mg dose. Phase 3 studies of grazoprevir 100 mg in combination with elbasvir are currently ongoing (NCT01710501; protocol P038)., (© 2015 Merck. Journal of Viral Hepatitis Published by John Wiley & Sons Ltd.)