A Study to Evaluate the Pharmacokinetics, Safety, and Efficacy of Glecaprevir/Pibrentasvir in Pediatric Subjects With Genotypes 1-6 Chronic Hepatitis C Virus (HCV) Infection

The objectives of this study are to assess the pharmacokinetics, safety, and efficacy of glecaprevir/pibrentasvir adult formulation in adolescents ages 12 to 17 years and a pediatric formulation of glecaprevir and pibrentasvir in children ages 3 to \< 12 years.

This was a multicenter study to evaluate the pharmacokinetics (PK), efficacy, and safety of glecaprevir (GLE) and pibrentasvir (PIB) treatment for 8, 12, or 16 weeks in hepatitis C virus (HCV) genotype 1 - 6 (GT1 - GT6)-infected pediatric participants 3 to \< 18 years of age, with or without compensated cirrhosis, with or without human immunodeficiency virus (HIV) coinfection, who are either treatment-naïve (TN), treatment-experienced (TE) with pegylated interferon (pegIFN) with or without ribavirin (RBV), or TE with sofosbuvir (SOF) + RBV with or without pegIFN.

The study was divided into 2 parts, according to the formulation of GLE/PIB administered. Part 1 of the study enrolled HCV GT1 - GT6 infected adolescent participants into the 12 to \< 18 years old age group who were willing to swallow the adult formulation of GLE/PIB (Cohort 1). Part 2 of the study enrolled HCV GT1 - GT6 infected pediatric participants divided into the 9 to \< 12 (Cohort 2), 6 to \< 9 (Cohort 3), and 3 to \< 6 (Cohort 4) years old age groups, to receive the pediatric formulation of GLE + PIB. Part 1 enrolled first and once the pediatric formulation was available enrollment into Part 2 commenced, with each cohort enrolled in parallel.

In each cohort, the first group of participants were enrolled into an intense pharmacokinetics (IPK) portion to characterize the PK and safety in each age group, followed by enrollment into a non-IPK safety/efficacy portion. Study participants enrolled in the IPK portion must have been HIV-negative, treatment-naive, and have an identified HCV genotype. In the IPK portion the first approximately six participants received an initial proposed dose of GLE and PIB based on the child's weight and age at screening. PK samples from these participants were evaluated to determine if therapeutic efficacious exposures were attained, comparable to those of adults, and if any dose adjustments were needed. After the intensive PK analysis results for the first six participants were available, enrollment of the remaining IPK portion resumed with subsequent participants receiving an adjusted final dose as applicable. Additional participants may have been required for further intensive PK analysis per age cohort if therapeutic exposure targets were not achieved.

Enrollment into the non-IPK safety and efficacy portions began when the dosing recommendations per age group based on the PK and clinical data from the IPK analysis were ascertained.

Eligibility Criteria:
Inclusion Criteria:

* Hepatitis C virus (HCV) infection demonstrated by positive anti-HCV antibody (Ab) and HCV ribonucleic acid (RNA) greater than or equal to 1000 International Unit (IU)/mL
* Subjects participating in the intense pharmacokinetic (IPK) part must have been HCV treatment-naive, with or without compensated cirrhosis (Child-Pugh A), human immunodeficiency virus type 1 (HIV-1) negative and must have had a Screening laboratory result indicating HCV genotype (GT) 1, 2, 3, 4, 5, or 6-infection.

Exclusion Criteria:

* Females who were pregnant or breastfeeding
* Positive test result for hepatitis B surface antigen (HbsAg) or positive test result for hepatitis B virus deoxyribonucleic acid (DNA)
* Participants with other known liver diseases
* Decompensated cirrhosis defined as: presence of ascites, history of variceal bleeding, lab values consistent with Child-Pugh class B or C cirrhosis