Study of Grazoprevir (MK-5172) and Elbasvir (MK-8742) in Japanese Participants With Chronic Hepatitis C (MK-5172-058)

This is a two-part study of grazoprevir (MK-5172) + elbasvir (MK-8742) in Japanese participants with chronic hepatitis C virus (HCV) genotype 1 (GT1). Part I is a dose-finding study; in Part II, participants will be randomly assigned to receive grazoprevir at the dose determined in Part I in combination with elbasvir. The primary study hypothesis is that the percentage of treatment-naïve participants in the Immediate Treatment Arm of Part II who achieve sustained viral response at 12 weeks after the end of all treatment (SVR12) will be greater than the reference rate of 75%. A separate study arm for cirrhotic participants will also be included in Part II; these participants will receive grazoprevir at the determined dose in combination with elbasvir.

In Part 1, HCV GT1 participants are randomized into one of two arms: 50 mg grazoprevir plus 50 mg elbasvir for 12 weeks during the double blinded (DB) period followed by 24 weeks of follow-up (FU) during an open-label (OL) period \[Arm 1\]; or 100 mg grazoprevir plus 50 mg elbasvir for 12 weeks during the DB followed by 24 weeks of FU during the OL \[Arm 2\]. Unblinding will occur after all participants complete FU Week 4 at which time the grazoprevir dose will be selected.

In Part 2, non-cirrhotic HCV GT1 participants and GT1 participants with compensated liver cirrhosis all receive the selected dose of grazoprevir (50 mg or 100 mg from Part 1) with 50 mg elbasvir for 12 weeks. Non-cirrhotic GT1 participants are randomized to receive either a) 12 weeks of active treatment immediately during the DB with 24 weeks of FU in the OL \[Arm 1/Immediate Arm\] or b) placebo for 12 weeks with 4 weeks of follow-up during the DB followed by 12 weeks of active treatment and 24 weeks of follow-up during the OL \[Arm 2/Deferred Arm\]. All cirrhotic participants \[Arm 3/Cirrhotic\] receive the selected dose immediately for 12 weeks during the DB with 24 weeks of FU during the OL.

Safety analyses for Part 1 and Part 2 arms will focus on the 12 week treatment phase plus the first 4 FU weeks. For the Part 2 Deferred Arm this will include the initial 12 week placebo treatment and first 4 weeks of FU. Efficacy analyses for Parts 1 and 2 will evaluate active treatment only (Weeks 1-12 for all arms except for Part 2 Deferred Arm which is weeks 16-28).

Part 1:

50 mg grazoprevir + 50 mg elbasvir treatment for 12 weeks, 24 weeks follow-up (Arm 1) 100 mg grazoprevir + 50 mg elbasvir treatment for 12 weeks, 24 weeks follow-up (Arm 2)

Part 2:

Selected dose of grazoprevir + 50 mg elbasvir treatment for 12 weeks, 24 weeks follow-up (Arm 1/Immediate) Placebo treatment for 12 weeks, 4 weeks follow-up, selected dose of grazoprevir + 50 mg elbasvir treatment for 12 weeks, 24 weeks follow-up (Arm 2/Deferred) Selected dose of grazoprevir + 50 mg elbasvir treatment for 12 weeks, 24 weeks follow-up (Arm 3/Cirrhotic)

Eligibility Criteria:
Inclusion Criteria:

* Has documented chronic Japanese HCV genotype (GT) 1 with no evidence of non-typeable or mixed GT infection
* Is treatment-naïve, or intolerant or non-responder to prior anti-HCV interferon (IFN)-based treatment without direct acting antiviral (DAA) therapy, prior IFN-based treatment with DAA therapy, or prior DAA therapy
* Agrees to the use of contraception if a female of reproductive potential

Exclusion Criteria:

* Has 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
* Is coinfected with hepatitis B virus or human immunodeficiency virus (HIV)
* Has a history of malignancy ≤5 years prior to signing informed consent except for adequately treated basal cell or squamous cell skin cancer or carcinoma in situ
* Has cirrhosis and liver imaging within 6 months of Day 1 showing evidence of hepatocellular carcinoma (HCC) or is under evaluation for HCC (Part 2 only)
* Has clinically-relevant drug or alcohol abuse within 12 months of screening
* Is a female and is pregnant or breast-feeding, or expecting to conceive or donate eggs from Day 1 and continue throughout treatment and follow-up (or longer if dictated by local regulations)
* Has any of the following conditions:
* Organ transplants (including hematopoietic stem cell transplants) other than cornea and hair
* Poor venous access
* History of gastric surgery (e.g., stapling, bypass) or subject with a history of malabsorption disorders (e.g., celiac sprue disease)
* History of a medical/surgical condition that resulted in hospitalization within the 3 months prior to enrollment, other than for minor elective procedures
* Medical/surgical conditions that may result in a need for hospitalization during the period of the study
* 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
* Has chronic hepatitis not caused by HCV, including but not limited to nonalcoholic steatohepatitis (NASH), drug-induced hepatitis, and autoimmune hepatitis