
    due to lack of feasibility of enrolling participants, the study was terminated early.
  
['hepatitis c virus infection']
['ldv/sof', 'rbv']

        Key Inclusion Criteria:

          -  HCV RNA > 15 IU/mL at screening

          -  HCV genotype 1 or 4

          -  Chronic HCV infection (≥ 6 months)

          -  Prior virologic failure after treatment with SOF in combination with simeprevir (SMV)
             ± RBV or with RBV ± pegylated interferon (PEG)

          -  Cirrhotic and non-cirrhotic as determined by standard methods

          -  Male and female individuals of childbearing potential who engage in heterosexual
             intercourse must agree to use protocol specified method(s) of contraception

        Key Exclusion Criteria:

          -  Prior exposure to approved or experimental non-structural protein (NS5A) inhibitors

          -  Prior exposure to nucleos(t)ide polymerase inhibitors, other than SOF

          -  Pregnant or nursing female or male with pregnant female partner

          -  Coinfection with HIV or hepatitis B virus

          -  Current or prior history of clinical hepatic decompensation

          -  Hepatocellular carcinoma or other malignancy (with exception of certain resolved skin
             cancers)

          -  Chronic use of systemic immunosuppressive agents

          -  History of clinically significant illness or any other medical disorder that may
             interfere with individual's treatment, assessment or compliance with the protocol

        Note: Other protocol defined Inclusion/Exclusion criteria may apply.
      