LDV/SOF Randomisation * 1:1 Open-label ≥ 20 years, Japanese Chronic HCV infection Genotype 1 HCV RNA ≥ IU/ml Treatment-naive, or pre-treated Compensated cirrhosis ** allowed Creatinine clearance ≥ 1 ml/s No HBV or HIV co-infection N = 171  LDV/SOF 90/400 mg 1 pill qd  RBV (divided dose): 600 mg/d if 60 to ≤ 80 kg, 1000 mg/d if ≤ 80 kg  Objective –Primary endpoint: SVR 12 (HCV RNA < 25 IU/ml), with 2-sided 95% CI –For naive patients without cirrhosis, SVR > 23% of the adjusted historical SVR null rate of 63%, 90% power; For other patients, no statistical hypothesis testing * Randomisation of naive patients stratified on cirrhosis (yes or no) ; Randomisation of pre-treated patients stratified on cirrhosis and prior response to previous therapy (relapse, non-response, IFN-intolerance) LDV-SOF G1 Japanese ** Liver biopsy (Metavir F4 or Ishak ≥ 5), or Fibroscan > 12.5 kPa LDV/SOF + RBV W12 SVR 12 N = 170 LDV-SOF Japanese Study: LDV/SOF ± RBV for genotype 1 in Japanese (GS-US ) Mikozami M, Lancet Infect Dis 2015;15:  Design

LDV/SOF, N = 171LDV/SOF + RBV, N = 170 Mean age, years6059 Female, %6057 Genotype 1a / 1b, %4 / 962 / 98 IL28B CC genotype, %5046 HCV RNA log 10 IU/ml, mean6.6 Cirrhosis, %2421 Treatment history, % Naive Pre-treated PEG-IFN + RBV PI + PEG-IFN + RBV Other Response to previous treatment Non-response Breakthrough or relapse IFN-intolerance Discontinuation, N02 (1 AE, 1 death) LDV-SOF Japanese Study: LDV/SOF ± RBV for genotype 1 in Japanese (GS-US ) LDV-SOF G1 Japanese Mikozami M, Lancet Infect Dis 2015;15: Baseline characteristics, and disposition

SVR 12 (HCV RNA < 25 IU/ml), % (95% CI), ITT * p < vs SVR null rate of 63%, for both comparisons LDV/SOFLDV/SOF + RBV 100 (98-100) 98 (95-100) 100 ( ) % ( ) All 100 ( ) NaiveExperienced ( ) Naive, no cirrhosis * ( ) 97.2 ( ) N = LDV-SOF Japanese Study: LDV/SOF ± RBV for genotype 1 in Japanese (GS-US ) LDV-SOF G1 Japanese Mikozami M, Lancet Infect Dis 2015;15:645-53

LDV-SOF Japanese Study: LDV/SOF ± RBV for genotype 1 in Japanese (GS-US )  Patients with NS5A RAV at baseline, N = 76 –SVR 12 in 42/42 on LDV/SOF –SVR 12 in 33/34 on LDV/SOF + RBV  1 virological failure Treatment-naive, genotype 1b, 55-year-old woman without cirrhosis who was receiving LDV/DOF + RBV, relapse by post-treatment W4 after completion of treatment. Adherence rates > 99% for both LDV/SOF and RBV (800 mg daily) Baseline NS5A RAV: Y93H (> 99%) NS5A. No other NS5A RAVs were detected at post-treatment W4  No NS5B RAVs and no treatment-emergent variants were detected in any patient at any timepoint tested LDV-SOF G1 Japanese Mikozami M, Lancet Infect Dis 2015;15:645-53

LDV/SOF N = 171 LDV/SOF + RBV N = 170 Treatment discontinuation due to adverse event, N02 * Death01 Serious adverse events, N Acute myocardial Infarction Cardiac arrest Hepatocellular carcinoma Oesophageal varices haemorrhage Wrist fracture ** 0 Common adverse events, % Nasopharyngitis Anemia Headache Pruritus Rash Malaise Stomatitis Nausea Decreased hemoglobin : < 10 g/dl / < 8.5 g/dl, N Lymphocyte count /mm 3, N Neutrophil count /mm 3, N Platelet count /mm 3, N 4 / / * drug eruption, N = 1, morbilliform rash, N = 1 ; ** related to study drug LDV-SOF Japanese Study: LDV/SOF ± RBV for genotype 1 in Japanese (GS-US ) LDV-SOF G1 Japanese Mikozami M, Lancet Infect Dis 2015;15: Adverse events

 Summary –In this trial, 12 weeks of treatment with the fixed-dose combination of LDV/SOF without RBV was well tolerated and resulted in SVR 12 in all 171 patients (100%) treated, including patients typically difficult to treat, including those with cirrhosis, or baseline NS5A RAVs, and those who had previously not responded well to other HCV treatment regimens, including PI-based therapies –The addition of RBV to LDV/SOF let to a SVR 12 of 97%, and was associated with an increased number of patients who had adverse events –Limitations of the study Open-label design Absence of an active comparator LDV-SOF Japanese Study: LDV/SOF ± RBV for genotype 1 in Japanese (GS-US ) LDV-SOF G1 Japanese Mikozami M, Lancet Infect Dis 2015;15:645-53