['chronic hepatitis c virus']
['grazoprevir 100mg / elbasvir 50 mg fdc', 'placebo to grazoprevir / elbasvir 50 mg fdc']

        Inclusion criteria:

          -  Documented chronic HCV GT1, GT4, or GT6 with no evidence of non-typeable or mixed
             genotype infection (positive for anti-HCV antibody, HCV RNA, or any of the listed GTs
             at least 6 months prior to screening must be confirmed by screening lab results)

          -  Cirrhosis defined by: liver biopsy showing cirrhosis METAVIR F4; or Fibroscan showing
             cirrhosis with a result of >12.5 kiloPascals (kPa); or FibroSure® (Fibrotest®) score
             of >0.75 and an aspartate aminotransferase (AST): platelet ratio index (APRI) of >2

          -  Absence of cirrhosis defined by: liver biopsy showing absence of cirrhosis, or
             Fibroscan with a result of ≤12.5 kPa, or Fibrosure® (Fibrotest®) score of <= 0.48 and
             APRI of <=1

          -  HCV treatment status of treatment naïve (naïve to all anti-HCV treatment) and can also
             be ineligible to take pegylated interferon

          -  Female participant not of reproductive potential, or female of reproductive potential
             and agrees to avoid becoming pregnant while receiving study drug and for 14 days after
             the last dose of study drug (using abstinence or acceptable methods of contraception)

        Exclusion criteria:

          -  Evidence of decompensated liver disease manifested by the presence of or history of
             ascites, esophageal or gastric variceal bleeding, hepatic encephalopathy or other
             signs or symptoms of advanced liver disease. For cirrhotics, participants who are
             Child-Pugh Class B or C or who have a Pugh-Turcotte (CPT) score >6

          -  Co-infection with hepatitis B virus or human immunodeficiency virus (HIV)

          -  History of malignancy <=5 years prior to signing informed consent except for
             adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer
             or carcinoma in situ; or is under evaluation for other active or suspected malignancy

          -  Evidence of hepatocellular carcinoma (HCC) or under evaluation for HCC

          -  Currently participating or has participated in a study with an investigational
             compound within 30 days of signing informed consent and is not willing to refrain from
             participating in another such study during the course of this study

          -  Clinically-relevant drug or alcohol abuse within 12 months of screening

          -  Pregnant, breast-feeding, or expecting to conceive or donate eggs from Day 1
             throughout treatment and 14 days after the last dose of study medication or longer if
             dictated by local regulations

          -  Organ transplant (including hematopoietic stem cell transplants) other than cornea and
             hair

          -  Poor venous access

          -  History of gastric surgery (e.g., stapling, bypass) or history of malabsorption
             disorder (e.g., celiac sprue disease)

          -  Any medical condition requiring, or likely to require, chronic systemic administration
             of corticosteroids, TNF antagonists, or other immunosuppressant drugs during the
             course of the trial

          -  Evidence of history of chronic hepatitis not caused by HCV, including but not limited
             to nonalcoholic steatohepatitis (NASH), drug-induced hepatitis, and autoimmune
             hepatitis
      