ARV-trial.com IMPACT Study: SMV + DCV + SOF in HCV genotype 1 with decompensated liver disease Design Open label ≥ 18 years Chronic HCV infection Genotype 1 or 4 HCV RNA > 10 000 IU/ml Treatment-naïve or pre-treated with PEG-IFN ± RBV Cirrhosis (> 14.5 kPa on FibroScan) Portal hypertension or liver decompensation No hepatocellular carcinoma Total bilirubin ≤ 3 x ULN, Platelet ≥ 30,000/mm3, Albumin ≤ 2.5 g/dl, INR ≤ 2.5, eGFR ≥ 30 ml/min No HBV or HIV co-infection W12 N = 19 CP A < 7 + PH SMV + DCV + SOF SVR12 N = 21 CP B 7-9 SMV + DCV + SOF CP : Child-Pugh ; PH : portal hypertension Post-treatment follow-up of 5 years SMV 150 mg qd + DCV 90 mg qd + SOF 400 mg qd Objective SVR12 (HCV RNA < 15 IU/ml), with 2-sided 95% CI, by ITT IMPACT Lawitz E. J Viral Hepat 2017; 24:287-94 1

Baseline characteristics ARV-trial.com IMPACT Study: SMV + DCV + SOF in HCV genotype 1 with decompensated liver disease Baseline characteristics CP A, N = 19 CP B, N = 21 Median age, years 56 61 Female, % 26 48 Race : white / black, % 95 / 5 100 / 0 Body mass index, median 26.8 31.8 Genotype, n 1a (NS3 Q80K) 1b 4 15 (9/15) 3 1 11 (3/10) 10 IL28B CC genotype, % 21 14 HCV RNA log10 IU/ml, median 5.78 5.60 Treatment-experienced, % 47 Fibroscan score, kPa, median 21.8 30.8 Child-Pugh score : 5 / 6 / 7 / 8 / 9, n 14 / 5 / 0 / 0 / 0 0 / 0 / 9 / 8 / 4 MELD score < 10 / 10-15 / ≥ 15, n 12 / 7 / 0 10 / 9 / 2 Albumin, g/dl, median 4.1 3.2 Platelets x 103/mm3, median 106 79 IMPACT Lawitz E. J Viral Hepat 2017; 24:287-94 2

ARV-trial.com IMPACT Study: SMV + DCV + SOF in HCV genotype 1 with decompensated liver disease Outcome CP A, N = 19 CP B, N = 21 SVR12 (HCV RNA < 15 UI/ml) 100% Change in Child-Pugh score at follow-up W12 Change in MELD score at follow-up W12 Baseline CP score -2 6 8 -6 -4 2 4 Baseline MELD score -3 -2 2 3 -1 1 5–6 7–9 < 10 ≥ 10-< 15 ≥ 15 Decreased, N = 11 No change, N = 23 Increased, N = 6 Decreased, N = 20 No change, N = 13 Increased, N = 7 IMPACT Lawitz E. J Viral Hepat 2017; 24:287-94 3

IMPACT Study: SMV + DCV + SOF in HCV genotype 1 with decompensated liver disease SMV, DCV and SOF pharmacokinetics following administration of SMV + DCV + SOF Intensive PK analysis performed at Week 2 and Week 8 Mean SMV exposure: 2.2-fold higher in CP B than CP A Mean DCV exposure: similar in CP B and CP A (1.2-fold higher in CP B) Mean SOF exposure: 1.5-fold higher in CP B than CP A Mean GS-331007 exposure (SOF metabolite): similar in CP B and CP A IMPACT Lawitz E. J Viral Hepat 2017; 24:287-94

IMPACT Study: SMV + DCV + SOF in HCV genotype 1 with decompensated liver disease Adverse events and laboratory abnormalities, N (%) CP A, N = 19 CP B, N = 21 Serious adverse event 1 (5) GI haemorrhage, not related Adverse event related to study drug 3 (16) 7 (33) Adverse event leading to discontinuation Death Adverse event in ≥ 2 patients in any group, N Pruritus Urinary tract infection Photosensitivity Nausea Hepatic encephalopathy Anemia Insomnia Irritability 1 2 1 0 Total bilirubin grade 3 / grade 4, N 2 / 0 5 / 2 Lipase grade 3 / grade 4, N 0 / 1 1 / 0 Glucose elevations grade 3 / grade 4, N 1 / 1 IMPACT Lawitz E. J Viral Hepat 2017; 24:287-94

IMPACT Study: SMV + DCV + SOF in HCV genotype 1 with decompensated liver disease Summary Treatment for 12 weeks with SMV, SOF, and DCV resulted in 100% response rate; all 19 Child-Pugh A patients and all 21 Child-Pugh B patients achieved SVR12 High virologic response was observed regardless of Child-Pugh class (<7 or 7–9) or the presence of resistance-associated variants at baseline This 3-DAA combination was generally safe and well tolerated No discontinuations due to adverse events No deaths 5-year follow-up will be important in providing long-term outcomes in association with SVR IMPACT Lawitz E. J Viral Hepat 2017; 24:287-94