To assess the efficacy and safety of 100 mg or 200 mg yimitasvir phosphate combined with sofosbuvir in patients with non-cirrhotic chronic hepatitis C virus (HCV) genotype 1 infection who were treatment-naïve or had a virologic failure to prior interferon-based treatment.

A multicenter, randomized, open-label, phase 2 clinical trial was conducted. The patients were randomly assigned to yimitasvir phosphate 100 mg+ sofosbuvir 400 mg group (Group 100 mg) and yimitasvir phosphate 200 mg+ sofosbuvir 400 mg group (Group 200 mg) in a 1∶1 ratio with the stratified factors of "treatment-naive" or "treatment-experienced" for 12 weeks and followed up for 24 weeks after the end of treatment. During the clinical trial, HCV RNA was tested in all patients. Resistance of virus in patients who didn′t achieved sustained virological response (SVR) was monitored. Safety and tolerability were assessed by monitoring adverse events, physical examination, laboratory examination, electrocardiogram, and vital signs during the study. The primary end point was SVR12 after the end of therapy. Descriptive statistics were used for categorical variables and eight descriptive statistics were used for continuous variables. Descriptive statistics were used and summarized according to HCV genotypes and treatment groups. Safety data were presented using descriptive statistics and summarized according to treatment groups.

A total of 174 subjects were screened from July 31, 2017 to September 26, 2018. One hundred and twenty-nine patients were successfully enrolled and received treatment, and 127 completed the study. There were 64 patients and 65 patients assigned to Group 100 mg and Group 200 mg, respectively. Among the 129 patients who underwent randomization and were treated, 18.6% were treatment-experienced and: 100% were HCV genotype 1b infection. The total SVR rate was 98.4% (127/129), with 98.4% (63/64, 95% confidence interval [CI]: 91.60%-99.96%) in the Group 100 mg, and 98.50% (64/65, 95%CI: 91.72%-99.96%) in the Group 200 mg. There was no significant difference between the two groups (χ²=0.000 2, P=0.989 2). The SVR rates in treatment-naive group and treatment-experienced group were 98.10% (95%CI: 93.29%-99.77%) and 100.00% (24/24, 95%CI: 85.75%-100.00%), respectively. Virological failure during treatment (including breakthrough, rebound and poor efficacy) and relapse after treatment did not occur during the trial. By Sanger sequencing, 11.6% (15/129) patients had baseline NS5A Y93H/Y or Y93H resistance-associated substitutions (RAS), 1.6% (2/129) patients had baseline NS5A L31M RAS. No mutation was observed in NS5B S282 at baseline. There was no S282 mutation in HCV NS5B. A total of 100 (77.5%) subjects had adverse events. No adverse events ≥Grade 3 or severe adverse events related to the study treatment. No patient prematurely discontinued study treatment owing to an adverse event. No life-threatening adverse event was reported.

Twelve weeks of yimitasvir phosphate 100 mg or 200 mg combined with sofosbuvir 400 mg daily is a highly effective and safe regimen for patients without cirrhosis with HCV genotype 1b infection who had not been treated previously or had a virologic failure to prior interferon-based treatment.

Hepatitis C, chronic; Yimitasvir; Sofosbuvir; Genotype 1; Viral therapy; Sustained virologic response; Safety