An Open-Label Study of Telaprevir Administered Every 12 or 8 Hours in Combination With One of Two Pegylated Interferons and Ribavirin in Treatment-Naive Genotype 1 Chronic Hepatitis C Participants

• Percentage of Participants With Virologic Response at Week 12 [ Time Frame: End of treatment (EOT) (up to Week 48) ] [ Designated as safety issue: No ]
  Virologic response was either defined as having undetectable Hepatitis C Virus (HCV) ribonucleic acid (RNA) (i.e., no HCV RNA was detected in the participants' plasma samples) or less than 25 international units/milliliter (IU/mL) HCV RNA (i.e., the participants' plasma samples contained traces of HCV RNA at a concentration below the limit of quantification of the viral load assay or no HCV RNA was detected in the samples).
  
  

• Time to First Undetectable Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Level [ Time Frame: Baseline (Day 1) up to EOT (up to Week 48) ] [ Designated as safety issue: No ]
  Virologic response was either defined as having undetectable HCV RNA (i.e., no HCV RNA was detected in the participants' plasma samples) or less than 25 IU/mL HCV RNA (i.e., the participants' plasma samples contained traces of HCV RNA at a concentration below the limit of quantification of the viral load assay or no HCV RNA was detected in the samples).
  
  
• Number of Participants With Viral Breakthrough at End of Treatment (EOT) [ Time Frame: EOT (up to Week 48) ] [ Designated as safety issue: No ]
  Viral breakthrough was defined as a confirmed increase of more than 1 log 10 in HCV RNA level from the lowest level reached or a confirmed value of HCV RNA more than 100 IU/mL in participants whose HCV RNA was previously less than 25 IU/mL.
  
  
• Percentage of Participants With Partial Response [ Time Frame: Baseline (Day 1) up to EOT (up to Week 48) ] [ Designated as safety issue: No ]
  Partial response was defined as having at least 2 log drop in HCV RNA from Baseline, but not having undetectable HCV RNA (i.e., no HCV RNA is detected in the participants' plasma samples).
  
  
• Change From Baseline in Log 10-Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Values at Week 12 [ Time Frame: Baseline (pre-dose), Week 12 ] [ Designated as safety issue: No ]
  Change from baseline in log 10 of Plasma HCV RNA levels were measured using the COBAS TaqMan HCV test (lower limit of quantification 25 IU/mL). The assay used real-time reverse transcription - polymerase chain reaction (RT-PCR) methodology. HCV RNA samples were taken pre-dose of Peg-IFN administration.
  
  
• Change From Baseline in Log 10-Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Values at End of Treatment (EOT) [ Time Frame: Baseline (pre-dose), EOT (up to Week 48) ] [ Designated as safety issue: No ]
  Change from baseline in log 10 of Plasma HCV RNA levels were measured using the COBAS TaqMan HCV test (lower limit of quantification 25 IU/mL). The assay used real-time reverse transcription - polymerase chain reaction (RT-PCR) methodology.
  
  
• Percentage of Participants With Sustained Viral Response 24 Weeks After End of Treatment (SVR24) [ Time Frame: Baseline (Day 1) up to 24 weeks after EOT ] [ Designated as safety issue: No ]
  SVR24 was defined as having undetectable HCV RNA (i.e., no HCV RNA is detected in the participants' plasma samples) at EOT and no confirmed detectable HCV RNA levels between EOT and 24 weeks after the last dose of study medication.
  
  

This is a Phase 2a, open-label (all people know the identity of the intervention), multicenter trial (conducted in more than one center) in participants with chronic genotype 1 HCV infection. The trial consists of a Screening phase of approximately 4 weeks, a treatment phase up to 48 weeks depending on participants' individual virologic response, and a follow-up phase of at least 24 weeks. All participants will receive 12 weeks of telaprevir treatment in combination with standard therapy. At Week 12, telaprevir dosing will end and participants will continue on standard therapy only. Participants will be randomly assigned to receive one of the two different dosage regimens of telaprevir (750 milligram [mg] every 8 hours (hr), or 1125 mg every 12 hr) in combination with standard therapy (pegylated interferon [Peg-IFN]-alfa-2a and ribavirin [RBV] or Peg-IFN-alfa-2b and RBV at the standard doses). Efficacy will be evaluated by HCV Ribonucleic Acid (RNA) values, viral response, viral breakthrough, partial response, early viral kinetics and sustained viral response. Pharmacokinetics, Pharmacokinetic-pharmacodynamic relationship will also be evaluated. Safety will be monitored throughout the study duration.