Simeprevir plus sofosbuvir, with or without ribavirin, to treat chronic infection with hepatitis C virus genotype 1 in non-responders to pegylated interferon and ribavirin and treatment-naive patients: the COSMOS randomised study

Background Interferon-free regimens are needed to treat hepatitis C virus (HCV) infections. We investigated the efficacy of combined simeprevir and sofosbuvir. Methods We enrolled patients with chronic HCV genotype 1 infections who had previously not responded to pegylated interferon (peginterferon) and ribavirin or were treatment naive. Patients were randomly assigned in a 2: 1: 2: 1 ratio to receive 150 mg simeprevir and 400 mg sofosbuvir daily for 24 weeks with (group 1) or without (group 2) ribavirin or for 12 weeks with (group 3) or without (group 4) ribavirin, in two cohorts: previous non-responders with METAVIR scores F0-F2 (cohort 1) and previous non-responders and treatment-naive patients with METAVIR scores F3-F4 (cohort 2). The primary endpoint was sustained virological response 12 weeks after stopping treatment (SVR12). Analysis was done by intention to treat. Safety data from cohorts 1 and 2 were pooled for analysis. This study is registered with ClinicalTrials. gov, number NCT01466790. Findings 168 patients were enrolled and randomised, and 167 started treatment (n=80 in cohort 1 and n=87 in cohort 2). SVR12 was achieved in 154 (92%) patients (n=72 [90%, 95% CI 81-96] in cohort 1 and n=82 [94%, 87-98] in cohort 2). The most common adverse events in the pooled groups were fatigue (n=52 [31%]), headache (n=33 [20%]), and nausea (n=26 [16%]). Grade 4 adverse events were seen in one (2%) of 54 patients in each of groups 1 and 3 and in three (10%) of 31 patients in group 2, whereas grade 3-4 events were reported in less than 5% of all patients, except increased blood amylase concentration. Serious adverse events were seen in four (2%) patients, all in groups 1 and 2. Four (2%) patients discontinued all study treatment because of adverse events, three before week 12. Interpretation Combined simeprevir and sofosbuvir was efficacious and well tolerated.