Chronic Hepatitis C Virus Related Thrombocytopenia to Evaluate the Effects of E5501

Inclusion Criteria: 1. Males or females greater than or equal to 18 years of age 2. Women of childbearing potential must agree to use a highly effective method of contraception for at least one menstrual cycle prior to starting study drug, throughout the entire study period, and for 30 days after the last dose of study drug 3. Subjects with chronic HCV-related thrombocytopenia (defined as a platelet count greater than or equal to 20x10\^9/L to 70x10\^9/L) who require antiviral treatment 4. Chronic HCV infection (defined as the presence of anti-HCV antibodies and detectable serum HCV RNA levels) 5. Model for End-stage Liver disease score greater than or equal to 24 6. Adequate renal function as evidenced by a calculated creatinine clearance greater than or equal to 50 mL/minute per the Cockcroft and Gault formula 7. Life expectancy greater than or equal to 3 months Exclusion Criteria: Subjects who meet any of the following criteria will be excluded from participation in the study: 1. Any history of arterial or venous thrombosis, including partial or complete thrombosis (e.g., stroke, transient ischemic attack, myocardial infarction, deep vein thrombosis or pulmonary embolism), thrombosis (partial or complete) in the main portal vein and portal vein branches, and thrombosis of any part of the splenic-mesenteric system 2. Any evidence of current portal vein thrombosis (PVT) as detected by Doppler sonography and portal vein flow rate less than 15 cm/second at Screening or within 30 days prior to Screening (revised per Amendment 02) 3. Any known family history of hereditary thrombophilic disorders (e.g., Factor V Leiden, antithrombin III deficiency) 4. Evidence of myocardial infarction in the last 6 months or uncompensated congestive heart failure (New York Heart Association Class III or IV) 5. Co-infection with human immunodeficiency virus (HIV) or hepatitis B or acute hepatitis C 6. Any prohibited concomitant medications or therapy that cannot be discontinued by Visit 1, e.g., subjects currently receiving interferon who cannot undergo a 4-week washout period prior to Screening, or subjects who receive blood products that affect platelet count within 1 week prior to Screening (revised per Amendment 02) 7. Weekly alcohol intake greater than 21 units (168 g) \[male\] and greater than 14 units (112 g) \[female\] 8. Any known medical condition, other than chronic liver disease, that can lead to thrombocytopenia 9. History of hepatocellular carcinoma, metastatic liver cancer, or liver transplantation (revised per Amendment 01) (revised per Amendment 02) 10. History of idiopathic thrombocytopenic Purpura (ITP) 11. History of myelodysplastic syndrome 12. History of pernicious anemia or subjects with vitamin B12 deficiency (defined as less than the lower limit of normal \[LLN\]) who have not had pernicious anemia excluded as a cause (Added per Amendment 02) 13. Evidence of clinically significant disease (e.g., cardiac, respiratory, gastrointestinal, renal disease) that, in the opinion of the investigator, could affect the subject's safety or study conduct 14. Subjects with a history of suicide attempts 15. Subjects with a history of hospitalization for depression within the past 5 years 16. Subjects with any current severe or poorly controlled psychiatric or seizure disorder 17. Current use of recreational drugs 18. Subjects who have participated in another investigational study within 30 days prior to Visit 1 19. Subjects with hypersensitivity, intolerance, or allergy to E5501 or any anti-HCV therapies or their ingredients 20. Any past or current (revised per Amendment 01) medical condition that, in the opinion of the investigator, would compromise the subject's ability to safely complete the study 21. Scheduled for surgery during the projected course of the study 22. Subjects who have any medical conditions or diseases that would contraindicate treatment with anti-HCV therapy (added per Amendment 01) 23. Subjects who are currently treated with proton pump inhibitors (PPIs) or H2-antagonist therapy but have not been receiving a stable dose for at least 6 weeks prior to randomization or have not completed these therapies more than 2 weeks prior to randomization (added per Amendment 01) 24. Fasting gastrin-17 blood levels exceeding 1.5 times the upper limit of normal (ULN) at Screening (including subjects on PPIs or H2 antagonists) (revised per Amendment 02) 25. Subjects with a history of gastric atrophy (added per Amendment 02)