C-BREEZE-2 Study: ruzasvir + uprifosbuvir for 12 weeks in genotype 1-6 Design W12 18-70 years HCV genotype 1-6 Treatment naïve or experienced (no prior DAA) HCV RNA ≥ 10,000 IU/ml No cirrhosis or compensated cirrhosis * HIV co-infection allowed No HBV co-infection N = 250 RZR + UPR SVR12 W0 2 cohorts: initial enrollment of 50 participants, and continue enrollment for a total of 250 patients if no safety criteria are met * Liver biopsy or Fibroscan® > 12.5 kPa or FibroSure® > 0.75 + APRI > 2 RZR : 180 mg QD ; UPR : 450 mg QD Objective SVR12 (HCV RNA < 15 IU/mL), full analysis set (FAS) : all participants who received ≥ 1 dose of study medication ; mFAS : exclusion of participants with non-virologic failure C-BREEZE-2 Lawitz E. AASLD 2017, Abs. 61 1

C-BREEZE-2 Study: ruzasvir + uprifosbuvir for 12 weeks in genotype 1-6 Baseline characteristics and SVR12 RZR + UPR 12W N = 282 Mean age, years 49.5 Female, % 45 Race : White / Asian / Black, % 78 / 10 / 8 Cirrhosis, % 21 Genotype 1a / 1b / 2 / 3 / 4 / 5 / 6, % 17 / 11 / 17 / 22 / 21 / 6 / 8 IFN treatment-experienced, % 16 SVR12 FAS mFAS ** 90% * 92% * 19 relapses , 2 discontinuations due to drug-related adverse events ** 8 patients excluded (7 discontinuations, 1 lost to follow-up) C-BREEZE-2 Lawitz E. AASLD 2017, Abs. 61 2

C-BREEZE-2 Study: ruzasvir + uprifosbuvir for 12 weeks in genotype 1-6 SVR12, mFAS, by genotype, % 259 45 30 45 59 55 3 22 * GT1a: 3 relapses ** GT2 : 1 non-compliance, 1 discontinuation due to drug-related adverse event (insomnia and fatigue) *** GT3: 14 relapses (SVR12 : 80% in non-cirrhotics vs 68% in cirrhotics) **** GT6 : 1 relapse, 1 discontinuation due to drug-related adverse event (anxiéty and nausea) C-BREEZE-2 Lawitz E. AASLD 2017, Abs. 61 3

C-BREEZE-2 Study: ruzasvir + uprifosbuvir for 12 weeks in genotype 1-6 SVR12, mFAS, according to baseline NS5A RAS in genotype 3 and 1a, % No RAS RAS present % 100 98 100 86 80 79 79 74 82 69 75 57 50 40 25 N 28 31 52 7 33 26 54 5 31 14 43 2 Any of 7 positions * A30 S62 Y93 Any of 4 positions ** Y93 Genotype 3 Genotype 1a * 24, 28, 30, 31, 58, 62, 93 ** 28, 30, 31, 93 (detection par next-generation sequencing with 15% sensitivity C-BREEZE-2 Lawitz E. AASLD 2017, Abs. 61

C-BREEZE-2 Study: ruzasvir + uprifosbuvir for 12 weeks in genotype 1-6 Adverse events, % RZR + UPR 12W N = 282 Any adverse event 61 Drug-related adverse event Fatigue Headache 33.3 7.8 7.4 Discontinuation due to adverse event 0.7 Serious adverse event 2.5 Discontinuation due to serious adverse event C-BREEZE-2 Lawitz E. AASLD 2017, Abs. 61 5

C-BREEZE-2 Study: ruzasvir + uprifosbuvir for 12 weeks in genotype 1-6 Summary Overall efficacy of the 2-drug regimen of ruzasvir + uprifosbuvir is suboptimal Lower efficacy in genotype 3; baseline RAS account for many failures High efficacy in other genotypes; potential impact of baseline Y93 RAS in GT1a, no impact of baseline RAS in other non-GT3 genotypes Good safety profile C-BREEZE-2 Lawitz E. AASLD 2017, Abs. 69 6