The study is designed to test the hypothesis that the addition of a protease inhibitor to dual NS5a-NS5B nucleoside prodrug analog will enhance antiviral efficacy and hence shorten the treatment duration to 3 weeks.

Inclusion Criteria:

• Age equal to or greater than 18 years, with chronic genotype 1b HCV infection;

• HCV RNA level > 10,000 and < 10,000,000 IU/ml at Screening;

• Rapid response to triple DAAs therapy with less than 500 IU/ml plasma HCV RNA level at Day 2;

• No evidence of cirrhosis. Cirrhosis defined as any 1 of the following, within 6 months of study entry:

  1. Liver biopsy showing cirrhosis;
  2. Fibroscan showing cirrhosis or results>12.5 kPa ;
  3. FibroTest® score >0.75 and an aspartate aminotransferase (AST): platelet ratio index (APRI) >2 during screening.

Exclusion Criteria:

• Pregnant or nursing female or male with pregnant female partner;
• HIV or chronic hepatitis B virus (HBV) infection;
• Hematologic or biochemical parameters at Screening outside the protocol-specified requirements;
• Active or recent history (≤ 1 year) of drug or alcohol abuse;
• Hepatocellular carcinoma or other malignancy (with exception of certain resolved skin cancers);
• History or current evidence of any condition, therapy, laboratory abnormality or other circumstance that might confound the results of the study, or interfere with the subject's participation for the full duration of the study, such that it is not in the best interest of the subject to participate.