An Efficacy, Safety and Pharmacokinetics Study of Simeprevir, Daclatasvir and Sofosbuvir in Participants With Chronic Hepatitis C Virus Genotype 1 or 4 Infection and Decompensated Liver Disease

The purpose of this study is to assess the efficacy of a 12-week regimen containing simeprevir, daclatasvir and sofosbuvir in participants with decompensated liver disease (the liver function is insufficient) due to genotype 1 or 4 Hepatitis (inflammation of the liver) C virus (HCV) infection by assessing sustained virologic response 12-weeks after the end of study drug treatment (SVR12).

This is an open-label (all people know which treatment the participants receive) Phase 2 study to investigate the efficacy, safety and pharmacokinetics of simeprevir, daclatasvir and sofosbuvir in treatment-naive (participants have never received HCV treatment with any approved or investigational agent) and treatment - experienced (participants have failed at least one previous course of \[Pegylated\] interferon \[(Peg)IFN\], with or without Ribavirin) participants. Participants will be assigned to 1 of 2 panels: Panel 1 (n=20): Child-Pugh score less than (\<) 7 with evidence of portal hypertension (confirmed by presence of esophageal varices or HVPG greater than or equal to \[\>=\] 10 mm Hg); Panel 2 (n=20): Child-Pugh score 7 to 9 (extremes included). The total study duration for each participant will be approximately 276 weeks. The study will consist of 3 parts: Screening Phase (approximately 4 weeks) and open-label treatment Phase (from Week 4 to 16) and follow-up Phase (until 5 years after the actual end of study drug treatment). Participants will receive simeprevir (150 milligram \[mg\] capsule), daclatasvir (60 mg tablet) and sofosbuvir (400 mg tablet) orally once daily for 12 weeks. Efficacy will be primarily evaluated by percentage of participants with SVR12. Participants' safety will be monitored throughout the study.

Eligibility Criteria:
Inclusion Criteria:

* Documented chronic Hepatitis C virus (HCV) infection: diagnosis of HCV more than (\>) 6 months before the Screening visit, either by detectable HCV ribonucleic acid (RNA), a HCV positive antibody or the presence of histological changes consistent with chronic hepatitis
* HCV genotype 1 or 4 infection and HCV RNA plasma level \>10,000 international unit per milliliter (IU/mL) (both determined at screening)
* Presence of cirrhosis, which is defined as a FibroScan with a result of \>14.5 kilopascals (kPa) at Screening
* HCV treatment-naive participants: participant has not received treatment with any approved or investigational drug for the treatment of HCV infection and HCV treatment-experienced participants: participant has had at least 1 documented previous course of a non-direct-acting antiviral agent (DAA), interferon (IFN)-based HCV therapy (with or without Ribavirin \[RBV\]). Last dose in this previous course should have occurred at least 2 months prior to Screening
* Decompensated liver disease: Panel 1: Child Pugh A (mild hepatic impairment) with evidence of portal hypertension \[confirmed by the presence of esophageal varices on gastroscopy or hepatic venous pressure gradient (HVPG) greater than or equal to (\>=) 10 millimeter of mercury (mm Hg)\], Panel 2: Child-Pugh B (moderate hepatic impairment) 7 to 9 (extremes included)

Exclusion Criteria:

* Co-infection with any HCV genotype
* Co-infection with human immunodeficiency virus (HIV)-1 or -2 (positive HIV-1 or HIV-2 antibodies test at Screening)
* Co-infection with hepatitis B virus (hepatitis B surface antigen \[HBsAg\] positive)
* Any evidence of liver disease of non-HCV etiology. This includes, but is not limited to, acute hepatitis A infection, drug- or alcohol-related liver disease, autoimmune hepatitis, hemochromatosis, Wilson's disease, alpha-1 antitrypsin deficiency, non-alcoholic steatohepatitis, primary biliary cirrhosis, or any other non-HCV liver disease considered clinically significant by the Investigator
* Use of any disallowed therapies before the planned first dose of study drugs