Durability of Virologic Response and/or Viral Resistance Patterns in Participants With Chronic Hepatitis C Who Have Been Previously Treated With Grazoprevir (MK-5172) (MK-5172-017)
Durability of Virologic Response and/or Viral Resistance Patterns in Participants With Chronic Hepatitis C Who Have Been Previously Treated With Grazoprevir (MK-5172) (MK-5172-017)
This is a three-year (except for participants with chronic kidney disease [CKD] or cirrhosis)
 multicenter study to follow participants who received at least one dose of grazoprevir
 (MK-5172) in a previous study to determine whether they remain hepatitis C virus (HCV)-RNA
 negative over time, and to determine if they have developed antiviral resistance. The study
 will also evaluate long-term adverse events in this population. Participants from MK-5172-052
 (NCT02092350) with CKD or cirrhosis will be followed for five years.
As of Amendment 03, the study design is revised such that continued enrollment will only be
 for participants who failed prior therapy with a grazoprevir regimen. Participants with CKD
 enrolled from MK-5172-052 (NCT02092350) will continue enrollment regardless of prior
 treatment-response and remain in this study for five years, while participants enrolled from
 all other studies with HCV RNA less than the lower limit of quantitation (LLOQ) will be
 discontinued and end their participation after the next scheduled visit. In addition,
 participants who receive other HCV treatments concurrent with this follow-up study or
 received other HCV treatments prior to this study will be discontinued and their data
 excluded from analysis.

 As of Amendment 04, the protocol has been updated to include enrollment of pediatric
 participants from protocol MK-5172-079 (NCT03379506). Enrollment is limited to participants
 who experienced virologic failure associated with 1 or more treatment-emergent resistant
 associated substitutions (RASs) present at 12 weeks after receiving grazoprevir treatment in
 prior treatment study MK-5172-079 (NCT03379506).
Inclusion Criteria:

 -  Previously participated in a HCV treatment protocol that included grazoprevir in the
 treatment regimen

 -  Must enroll in the present study within three months of the last study visit of their
 previous protocol in which they received a grazoprevir-containing regimen

 -  For Amendment 03: Adult participants must have received a grazoprevir-containing
 regimen in a prior trial and have been identified as having failed therapy in that
 study

 -  For Amendment 04: Pediatric participants must have received at least 1 dose of a
 grazoprevir-containing regimen and experienced virologic failure with 1 or more
 associated treatment-emergent RASs at Follow-up Week 12 in MK-5172-079 (NCT03379506)

 Exclusion Criteria:

 -  Has received HCV therapy after completion of the protocol-defined grazoprevir
 treatment trial regimen and before or after entry into this follow-up study

 -  For Amendment 03: Has failed therapy due to re-infection, defined as an HCV RNA sample
 with a different genotype than the baseline genotype in the prior treatment study, or
 an HCV RNA sample determined to be reinfection by phylogenetic analysis with
 comparison to the baseline sequence in the prior treatment study

 -  For Amendment 03: Has failed therapy and received retreatment with HCV therapy, except
 in the case where they were re-treated in a Merck-sponsored protocol