Simeprevir in combination with sofosbuvir in treatment-naïve and -experienced patients with hepatitis C virus genotype 4 infection: a Phase III, open-label, single-arm study (PLUTO).

BACKGROUND: Hepatitis C virus (HCV) infection is a leading cause of liver cirrhosis and subsequent hepatocellular carcinoma. HCV genotype 4 is found widely in the Middle East, Egypt and Africa, and has also spread into Europe. There are limited data available regarding the use of direct-acting antiviral agents in HCV genotype 4-infected patients with cirrhosis. AIM: To evaluate in the phase III, open-label, single-arm PLUTO study the efficacy and safety of 12 weeks of simeprevir (HCV NS3/4A protease inhibitor) plus sofosbuvir (HCV nucleotide-analogue NS5B polymerase inhibitor) in treatment-naïve and (peg)interferon ± ribavirin-experienced HCV genotype 4-infected patients, with or without compensated cirrhosis. METHODS: Adult patients with chronic HCV genotype 4 infection received simeprevir 150 mg once-daily and sofosbuvir 400 mg once-daily for 12 weeks. The primary efficacy endpoint was sustained virologic response 12 weeks after the end of treatment (SVR12). Safety was also assessed. RESULTS: Forty patients received treatment; the majority were male (73%) and treatment-experienced (68%). Overall, 7/40 (18%) patients had compensated cirrhosis. All patients achieved SVR12 [100% (Clopper-Pearson 95% confidence interval: 91-100%)]. Adverse events, all Grade 1 or 2, were reported in 20/40 (50%) patients. No serious adverse events were reported and no patients discontinued study treatment. Grade 3 treatment-emergent laboratory abnormalities were noted in 2/40 (5%) patients. CONCLUSIONS: Treatment with simeprevir plus sofosbuvir for 12 weeks resulted in SVR12 rates of 100% in treatment-naïve and -experienced patients with HCV genotype 4 infection with or without compensated cirrhosis, and was well tolerated. [NCT02250807].

Virology analyses of HCV genotype 4 isolates from patients treated with simeprevir and peginterferon/ribavirin in the Phase III RESTORE study.

Simeprevir is a hepatitis C virus NS3/4A protease inhibitor. Hepatitis C virus baseline NS3/4A polymorphisms and emerging mutations were characterized in treatment-naїve and treatment-experienced genotype 4-infected patients treated with simeprevir+peginterferon/ribavirin in the RESTORE study. Population sequencing of the NS3/4A region was performed and in vitro simeprevir activity against site-directed mutants or chimeric replicons with patient-derived NS3 protease sequences was assessed in a transient replicon assay. Simeprevir remained active against most (83/91 [91%]) baseline isolates tested in the chimeric replicon assay. Eight baseline isolates reduced simeprevir activity; these carried I132L or D168E substitutions reducing simeprevir median activity by 4.6- and 39-fold, respectively. Six of these eight isolates were from patients achieving sustained virologic response. Baseline NS3 Q80K polymorphism was not observed in the genotype 4-infected patients. Of the 107 simeprevir-treated patients, 37 did not achieve sustained virologic response for any reason. Of the 32 patients who failed treatment and had sequencing information, 28 (88%) had emerging mutations at NS3 positions 80, 122, 155, 156 and/or 168 at time of failure, similar to those in genotype 1. Emerging mutations were mainly D168V and D168E alone or combined with mutations at position 80. In general, isolates obtained at time of failure displayed high-level in vitro resistance to simeprevir (fold change ≥50) in a chimeric replicon assay with a median simeprevir fold change value of 440, consistent with observed mutations. In conclusion, emerging mutations in genotype 4 patients failing simeprevir+peginterferon/ribavirin treatment were similar to those in genotype 1 and conferred high-level resistance to simeprevir.