The purpose of this amendment included the following: to add text to the benefit and risks section; clarify screening procedures; clarify that that subjects continue into Substudy 2 after completing or discontinuing Substudy 1; clarify that sites may substitute serum pregnancy testing for urine pregnancy testing only if required per local regulations; added clinical laboratory and IP-10 testing to Table 2 at the Discontinuation visit; added subgenotypes to the exploratory analyses text.

The purpose of this amendment included the following: to exclude subjects with prior null or partial response to PegIFN/RBV in whom resistant variants associated with decreased susceptibility to ABT-450 and/or ABT-267 were detected; increased the enrollment time up to 1 year after virologic failure in the previous study; revised the Screening Visit procedures; clarified inclusion criteria text for woman of child bearing potential and define postmenopausal state; clarified inclusion criteria for male subjects who had partners of childbearing potential; added exclusion criteria to exclude use of herbal supplements and colony stimulating factors; added non-efficacy (futility) criteria; added information for the management of neuropsychiatric complications; added text to provide information on managing complications due to peginterferon therapy; and removed Abbott Realtime HCV testing, as exploratory analysis of HCV RNA results using 2 platforms was no longer planned.

The purpose of this amendment included the following: added a pre-screening visit to study procedures; updated the number of weeks of treatment with ABT-450 and ABT-267 in active clinical trials to 24 weeks; added inclusion criteria and exclusion criteria text to limit the enrollment to subjects with genotype 1 chronic HCV infection; added inclusion criteria text regarding HCV RNA level at pre-screening; clarified exclusion criteria text to align with how population sequencing was performed; added exclusion criteria related to the gap between the time the subject failed treatment in the previous AbbVie/Abbott DAA combination study and the start of this study; clarified that medical history will only be an update at the Screening Visit and Substudy 1 Day 1 Visit of new information that was not already recorded in the previous Abbott study; added text to clarify what treatment was planned after the subject ended their participation in this study; clarified physical examination procedures; added text regarding clinical laboratory tests to confirm post-menopausal status; corrected centrifuge speed text; added storage condition instructions for ritonavir; clarified text regarding assigning subjects; clarified drug accountability documentation; and updated references to include the newest versions of ABT-450 and ABT-267 Investigator's Brochures.

The purpose of this amendment included the following: revised inclusion/exclusion criteria and study procedures; revised the number of participating subjects in the study from 250 to 150; updated the description of the Treatment Period and the Post-Treatment Period including descriptions of study visits; modified inclusion criteria regarding effective contraceptive methods for female subjects; clarified exclusion criteria text to indicate that pregnancy should be avoided within 7 months after last dose of RBV study drug; added a table of medications contraindicated for use with ABT-450 and ABT-267 to exclusion criteria text; added urine albumin test to Substudy 1 Day 1 visit; deleted comprehensive physical examination from the Post Treatment Period; deleted the 1-year restriction for subjects to enroll into this study from discontinuation of the previous study; added clarifying text to the following sections: Prohibited Therapy, Pregnancy, Discontinuation of Individual Subject, Method of Assigning Subjects to Treatment Groups, Treatment Compliance, Drug Accountability, and Appropriateness of Measurements; updated the Toxicity Management; updated the Statistical Methods and Determination of Sample Size text; updated the Resistance Variables text; incorporated Administrative Changes 2 and 3; and provided clarifying text to address the Sponsor change from Abbott Laboratories (Abbott) to AbbVie.

The purpose of this amendment was to add text that prohibited the use of hormonal contraceptives during study drug administration.

The purpose of this amendment included the following: updated the Introduction text; updated the discussion text regarding the risk of treatment failure for subjects who previously failed pegIFN/RBV plus telaprevir; updates throughout to include subjects who failed pegIFN/RBV plus telaprevir in the previous AbbVie/Abbott study; clarified the expectations for rescreening procedures and eligibility; updated and clarified eligibility determination for both male and female subjects; amended the eligibility determination for subjects who failed telaprevir plus PegIFN/RBV therapy in the previous AbbVie study; updated the eligibility criterion for contraindicated medications; modified the hemoglobin exclusion criterion text; amended the prohibited therapy text; modified the study activities table and text; amended the treatment compliance and drug accountability text; updated the primary contact information for protocol deviations; and updated the resistance analyses to be performed; and added an appendix with clinical toxicity grade information.

The purpose of this amendment included the following: Amended the Pre-Screening and Screening sections regarding timing of the discontinuation visit from the previous AbbVie/Abbott DAA combination study; revised the assessments not required to be re-tested during the re-screening visit; clarified subjects that would not be permitted to re-screen and were excluded from the study; updated the Post-Treatment follow-up period text to allow subjects the ability to enroll in a follow-up study; amended the post-treatment therapy section; modified the study activities table and text; amended the information provided to the subjects; modified the Medication Event Monitoring System caps distribution text; amended the Non-Efficacy (Futility) Criteria text; updated the type of treatments dispensed in this study to include the possibility of receiving ritonavir tablets; for PegIFN, amended the treatment compliance and drug accountability text; amended the hematologic toxicities table to remove extra management criteria and to add another management criterion; amended the Statistical Methods and Resistance Analyses text; and corrected the protocol signatories in Appendix B.

The purpose of this amendment included the following: amended the number of subjects from approximately 150 to up to 150; updated the Introduction text to ensure that the most current drug development information was included; amended the toxicity management for Grades 1 and 2 laboratory abnormalities and modified instructions regarding the management of total bilirubin and/or hepatic transaminase and creatinine clearance decreases.

The purpose of this amendment included the following: updated the section for hormonal contraception to more clearly define the acceptable approaches to contraception during the study, and updated the information about the medication that is contraindicated for use with the study drug regimen.

The purpose of this amendment included the following: corrected the number of subjects to be enrolled; updated the Study Designated Physician details; updated the collection time point for HCV RNA level at screening and changed the collection time for archive plasma samples; removed the collection of Medication Event Monitoring System caps data; removed interim analyses; clarified in the protocol how and when samples were to be disposed of; corrected RBV dispensing text; updated the SAE section; and added contact information for subject safety concerns or medical emergencies.