No HBV or HIV co-infection MAGELLAN-I Study, Part 1: Glecaprevir + Pibrentasvir in genotype 1 with failure to DAA regimen – Phase II Design W12 Randomisation Open-label N = 6 * GLE 200 mg qd + PIB 80 mg qd SVR12 18-70 years HCV genotype 1 Failure to DAA regimen HCV RNA > 10 000 IU/ml No cirrhosis No HBV or HIV co-infection GLE 300 mg qd + PIB 120 mg qd + RBV 800 mg qd N = 22 ** SVR12 GLE 300 mg qd + PIB 120 mg qd N = 22 ** SVR12 * Low dose arm halted (based on dose-findings results across all genotypes) ** Randomisation stratified by genotype (1b or non-1b) and prior treatment (NS5A inhibitor-experienced, NS3/4A PI-experienced but NS5A inhibitor-naive, or other) Objective SVR12 (HCV RNA < 25 IU/ml), by ITT MAGELLAN-I, Part 1 Poordad F. Hepatology. 2017 ; 66 : 389-97 1

Baseline characteristics MAGELLAN-I Study, Part 1: Glecaprevir + Pibrentasvir in genotype 1 with failure to DAA regimen – Phase II Baseline characteristics GLE 200 mg + PIB 80 mg N = 6 GLE 300 mg + PIB 120 mg + RBV 800 mg N = 22 GLE 300 mg + PIB 120 mg Median age, years 59 56 Female, % 50 9 18 Race : White , % 67 77 55 Median BMI, kg/m2 27 28 Genotype 1a, % 91 82 Median HCV RNA, log10 IU/ml 6.1 6.7 6.6 Fibrosis stage (%) : F0-F1 / F2 / F3 67 / 17 / 17 77 / 0 / 23 50 / 27 / 23 Study drug discontinuation, N 1 1 (breakthrough) Prior regimen PI-experienced, NS5A naïve, N = 25 ; NS5A-experienced, PI-naïve, N = 8 PI and NS5A-experienced, N = 17 SOF-experienced, N = 16 MAGELLAN-I, Part 1 Poordad F. Hepatology. 2017 ; 66 : 389-97 2

MAGELLAN-I Study, Part 1: Glecaprevir + Pibrentasvir in genotype 1 with failure to DAA regimen – Phase II GLE 200 + PIB 120 GLE 300 + PIB 120 + RBV 800 GLE 300 + PIB 120 SVR12, ITT, % (95% CI) SVR12, ITTm 6 22 95 (78-99) 86 (67-95) N= % 100 (61-100) 95 % 100 6 22 20 Breakthrough 1 Relapse Lost to follow-up 2 1 MAGELLAN-I, Part 1 Poordad F. Hepatology. 2017 ; 66 : 389-97 3

MAGELLAN-I Study, Part 1: Glecaprevir + Pibrentasvir in genotype 1 with failure to DAA regimen – Phase II 2 virologic failures in genotype 1a Prior DAA regimen(s) Response / Regimen NS3 RAVs NS5A RVAs Baseline Failure OBV/PTV/r + DSV + RBV Breakthrough / GLE + PIB Y56H, D168A/T V36M, D168A M28V, Q30R, H58C M28G, Q30R, H58C DCV ; TVR + PR Relapse / GLE + PIB + RBV None A156V L31M H58D Q30R, L31M, H58D SVR12 (ITTm) according to baseline RAVs No RAVs N = 10 NS3 RAVs only N = 14 NS5A RAVs only N = 11 NS3 & NS5A RAVs N = 15 SVR12 100% 91% 93% MAGELLAN-I, Part 1 Poordad F. Hepatology. 2017 ; 66 : 389-97 4

Adverse events and laboratory abnormalities, % MAGELLAN-I Study, Part 1: Glecaprevir + Pibrentasvir in genotype 1 with failure to DAA regimen – Phase II Adverse events and laboratory abnormalities, % GLE 200 mg + PIB 80 mg N = 6 GLE 300 mg + PIB 120 mg + RBV 800 mg N = 22 GLE 300 mg + PIB 120 mg Any adverse event 83 86 77 Treatment-related serious adverse event Adverse event leading to discontinuation Adverse events in > 10% of patients Headache Fatigue Nausea Insomnia 17 23 36 27 18 14 Laboratory abnormalities, N ALT grade ≥ 2 / AST grade ≥ 2 Total bilirubin grade 2 Alkaline phosphatase grade ≥ 2 Hemoglobin grade ≥ 2 3 MAGELLAN-I, Part 1 Poordad F. Hepatology. 2017 ; 66 : 389-97 5

MAGELLAN-I Study, Part 1: Glecaprevir + Pibrentasvir in genotype 1 with failure to DAA regimen – Phase II Summary High SVR12 rates after 12 weeks of Glecaprevir + Pibrentasvir with only 2 virologic failures in 50 DAA-experienced genotype 1 patients without cirrhosis Baseline NS3 and/or NS5A RAVs did not impact SVR12 (most patients (≥ 80%) had at least 1 baseline polymorphism in NS3 or NS5A) RBV did not increase SVR12 rate Good tolerability, with mild adverse events No grade 3 or 4 laboratory abnormalities No discontinuation due to adverse events MAGELLAN-I, Part 1 Poordad F. Hepatology. 2017 ; 66 : 389-97 6