Study to Assess Efficacy and Safety of Grazoprevir/Elbasvir Associated With Sofosbuvir and Ribavirin in HCV Genotype 1 or 4-infected Patients Who Failed Direct Acting Antivirals (DAA) Bitherapy With Sofosbuvir

Inclusion Criteria: * Adult ≥18 years * Infection with HCV genotype 1 or 4, confirmed by detectable HCV RNA at pre-inclusion * Failure to a prior therapy with Sofosbuvir +/- Ribavirin associated with Simeprevir or Daclatasvir or Ledipasvir, with documented presence of NS5A or NS3/4A RAVs (Resistance Associated Variants) at the time of failure (presence of RAVs on at least one sample since the time of failure). The proportion of patients previously treated with Simeprevir will be limited to a third of all patients included. * Fibrosis at any stage * Men and women of child-bearing age and their heterosexual partners must use adequate contraceptions from 15 days before their inclusion in the study up to 7 months after the end of treatment for men and up to 4 months after the end of treatment for women * Written informed consent signed by the patient and the investigator (on the day of the pre-inclusion at the latest and before any examination required by the study) (article L1122-1-1 Public Health Code) * Patients with Health insurance (Sécurité Sociale or Couverture Médicale Universelle) Exclusion Criteria: * Child B or C cirrhosis (or Child A patients with history of Child B) * Patients with documented presence of RAVs conferring resistance to sofosbuvir * Positive HBs Antigen * Confirmed HIV-1 or HIV-2 infection * Pregnant or breast-feeding women or men whose female partners are pregnant * Transplant recipients * Any evolutive ongoing malignant disease, including hepatocellular carcinoma, which will be specifically screened for before inclusion * History of severe rhythm disorders or cardiac disease (coronary artery disease, heart failure, arteriopathy,…): the opinion of a cardiologist is compulsory (\< 6 months) * Consumption of alcohol which, in the investigator's opinion, will be an obstacle to the patient's participation and to his/her remaining in the study * Drug addiction which, in the investigator's opinion, will be an obstacle to the patient's participation and to his/her remaining in the study. Patients included in a programme of substitution with methadone or buprenorphine could be included. The opinion of an addictology consultant is recommended for patients presenting with current drug use or drug use in the past year * Patients taking part in another clinical trial within 30 days prior to inclusion * Patient under guardianship, trusteeship or judicial protection Non-inclusion biological criteria * Hemoglobin \< 11 g/dL * Platelets \< 50 000/mm3 * INR \> 1.5 unless subject has known hemophilia or is stable on an anticoagulant regimen affecting INR * ALT or AST \> 10xULN * Creatinine clearance \< 50 mL/mn (MDRD formula) * Albumin \< 30 g/L * HbA1c \> 10% (only in diabetic patients) Criteria related to study drugs * Contra-indication to treatment with Grazoprevir/Elbasvir, Sofosbuvir or Ribavirin including a history of hypersensitivity to one of their excipients * Patients with a non-compliance history, who will be at risk of not complying with the study follow-up timetable * Treatment with contra-indicated associated drugs