Study of Efficacy and Safety of Grazoprevir (MK-5172)/Elbasvir (MK-8742) Combination Regimen for Treatment-Naïve Participants With Chronic Hepatitis C Virus Genotypes 1, 4, and 6 (MK-5172-060)

Inclusion criteria:

• Documented chronic HCV GT1, GT4, or GT6 with no evidence of non-typeable or mixed genotype infection (positive for anti-HCV antibody, HCV RNA, or any of the listed GTs at least 6 months prior to screening must be confirmed by screening lab results)
• Cirrhosis defined by: liver biopsy showing cirrhosis METAVIR F4; or Fibroscan showing cirrhosis with a result of >12.5 kiloPascals (kPa); or FibroSure® (Fibrotest®) score of >0.75 and an aspartate aminotransferase (AST): platelet ratio index (APRI) of >2
• Absence of cirrhosis defined by: liver biopsy showing absence of cirrhosis, or Fibroscan with a result of ≤12.5 kPa, or Fibrosure® (Fibrotest®) score of <= 0.48 and APRI of <=1
• HCV treatment status of treatment naïve (naïve to all anti-HCV treatment) and can also be ineligible to take pegylated interferon
• Female participant not of reproductive potential, or female of reproductive potential and agrees to avoid becoming pregnant while receiving study drug and for 14 days after the last dose of study drug (using abstinence or acceptable methods of contraception)

Exclusion criteria:

• Evidence of decompensated liver disease manifested by the presence of or history of ascites, esophageal or gastric variceal bleeding, hepatic encephalopathy or other signs or symptoms of advanced liver disease. For cirrhotics, participants who are Child-Pugh Class B or C or who have a Pugh-Turcotte (CPT) score >6
• Co-infection with hepatitis B virus or human immunodeficiency virus (HIV)
• History of malignancy <=5 years prior to signing informed consent except for adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer or carcinoma in situ; or is under evaluation for other active or suspected malignancy
• Evidence of hepatocellular carcinoma (HCC) or under evaluation for HCC
• Currently participating or has participated in a study with an investigational compound within 30 days of signing informed consent and is not willing to refrain from participating in another such study during the course of this study
• Clinically-relevant drug or alcohol abuse within 12 months of screening
• Pregnant, breast-feeding, or expecting to conceive or donate eggs from Day 1 throughout treatment and 14 days after the last dose of study medication or longer if dictated by local regulations
• Organ transplant (including hematopoietic stem cell transplants) other than cornea and hair
• Poor venous access
• History of gastric surgery (e.g., stapling, bypass) or history of malabsorption disorder (e.g., celiac sprue disease)
• Any medical condition requiring, or likely to require, chronic systemic administration of corticosteroids, TNF antagonists, or other immunosuppressant drugs during the course of the trial
• Evidence of history of chronic hepatitis not caused by HCV, including but not limited to nonalcoholic steatohepatitis (NASH), drug-induced hepatitis, and autoimmune hepatitis