This is a Phase 2b, Randomized, Double-Blind, Placebo-Controlled Trial Evaluating Response Guided Therapy using Combinations of Oral Antivirals (GS-5885, tegobuvir, and/or GS-9451) with Peginterferon Alfa 2a and Ribavirin in Treatment Experienced Subjects with Chronic Genotype 1 Hepatitis C Virus (HCV) Infection.

In September 2011, the FDA requested that Gilead make several major changes to this study because of side effects experienced by two patients in other Gilead studies.

In 2 HCV-infected people that were given tegobuvir with another experimental medication plus interferon and ribavirin, big reductions in the number of white blood cells, red blood cells and platelets were seen. Because these cases might have been related to tegobuvir when given with interferon, ribavirin and another direct antiviral agent, tegobuvir is no longer being given to people with these other medications in this study.

As a result, the study is now open label which means both you and your study doctor will know the medication you will be receiving and Arms 1 and 3 have been discontinued from the study.

All subjects enrolled in the study as of September 2nd 2011 will receive Response Guided Therapy (RGT) with both GS-5885 and GS-9451 plus PEG and RBV.

Inclusion Criteria:

• Male or female, aged from 18 to 70 years old, inclusive

• Chronic HCV infection for at least 6 months prior to Baseline

• Subjects must have liver biopsy results (≤ 3 years prior to screening) indicating the absence of cirrhosis.

• Monoinfection with HCV genotype 1

• HCV RNA > 10^4 IU/mL at Screening

• Prior treatment and adherence (as defined by receiving at least 80% of the prescribed treatment) with one course of a pegylated interferon-alfa (Pegasys or Peg-Intron) and RBV

• The subject's medical records must include sufficient detail of prior treatment with pegylated interferon-alfa and RBV (start/stop dates and viral response) to allow for categorization of prior response as either

  • Non-Responder: Subject did not achieve undetectable HCV RNA levels during or at the end of a treatment period of at least 12 weeks duration. Within Nonresponders, subjects will be further defined as Null or Partial Responders if they had < 2 log10 or ≥ 2 log10 reduction, respectively, in HCV RNA during the first 12 weeks of treatment
  • Responder: Subject achieved undetectable HCV RNA during treatment. Within Responders, subjects will be further defined as Relapsers if they had undetectable HCV RNA at the end of at least 42 weeks of treatment but detectable HCV RNA levels observed within 1 year of the end of treatment and Breakthrough subjects if they achieved undetectable HCV RNA levels during the treatment period but detectable HCV RNA at the end of treatment.

• No prior treatment with an oral HCV antiviral (exclusive of RBV).

• Body mass index (BMI) 18-36 kg/m2, inclusive.

• Screening ECG without clinically significant abnormalities and with QTcF interval (QT corrected using Fridericia's formula) ≤ 450 msec for males and ≤ 470 msec for females

• Creatinine clearance ≥ 50 mL/min.

• Agree to use two forms of highly effective contraception for the duration of the study and for 6 months after the last dose of study medication. Females of childbearing potential must have a negative pregnancy test at Screening and Baseline

Exclusion Criteria:

• Discontinued prior treatment with pegylated interferon-alfa and RBV due to an adverse event, toxicity reasons or were lost to follow-up.
• Exceed defined thresholds for leukopenia, neutropenia, anemia, thrombocytopenia, thyroid stimulating hormone (TSH)
• Diagnosis of autoimmune disease, decompensated liver disease, poorly controlled diabetes mellitus, significant psychiatric illness, severe chronic obstructive pulmonary disease (COPD), HIV, hepatitis B virus (HBV), or another HCV genotype, hepatocellular carcinoma or other malignancy (with exception of certain skin cancers), hemoglobinopathy, retinal disease, or are immunosuppressed.
• Current use of amphetamines, cocaine, opiates (e.g., morphine, heroin), or ongoing alcohol abuse are excluded. Subjects on stable methadone are excluded, however stable buprenorphine maintenance treatment for at least 6 months is not exclusionary
• Receiving any of the prohibited concomitant medications.