An Open-label Safety Study of Lusutrombopag (S-888711) in Adults With Chronic Immune Thrombocytopenia (ITP)

Inclusion Criteria: * Subjects who previously participated in Study 0913M0621 (NCT01054443) and who completed treatment or discontinued treatment due to a platelet count \> 400,000/μL and continued to meet all inclusion criteria of the previous study, listed below, including platelet counts \< 50,000/μL were eligible for study participation. For the purpose of this study, initial screening visit and all prestudy time period refer to Study 0913M0621. * A signed and dated written informed consent * Males and females ≥ 18 years of age * All subjects must agree to use barrier contraception * Diagnosis of ITP * Subjects \> 60 years must have had a diagnostic bone marrow aspiration * Relapsed persistent or chronic ITP status, with or without prior splenectomy * Subjects receiving steroid therapy must be on a stable dose for at least 2 weeks prior to Screening * Prothrombin time (PT) and activated partial thromboplastin time (aPTT) within 20% of the upper limit of normal (ULN) at Screening * Subjects receiving stable dosages of cyclosporine A, mycophenolate mofetil, azathioprine, or danazol are allowed Exclusion Criteria: * History of clinically important hemorrhagic clotting disorder * Females who are pregnant, lactating, or taking oral contraceptives * History of alcohol/drug abuse or dependence within 1 year * Use of the following drugs or treatment prior to Visit 1 (Day 1): * Within 1 week - Rho(D) immune globulin or intravenous immunoglobulin; * Within 2 weeks - plasmaphoresis treatment; * Within 4 weeks - use of anti-platelet or anti-coagulant drugs; * Within 8 weeks - rituximab; * Within 12 weeks - alemtuzumab, multi-drug systemic chemotherapy, stem cell therapy; * History of clinically significant cardiovascular or thromboembolic disease within 26 weeks prior to Initial Screening * Splenectomy within 4 weeks prior to Initial Screening * Clinically significant laboratory abnormalities * Hemoglobin \< 10.0 g/dL for men or women, not clearly related to ITP * Absolute neutrophil count \< 1000/mm3 * Abnormal peripheral blood smear with evidence of fibrosis confirmed by bonemarrow biopsy * Total bilirubin \> 1.5 x upper limit of normal * Alanine aminotransferase (ALT) \> 1.5 x upper limit of normal * Aspartate aminotransferase (AST) \> 1.5 x upper limit of normal * Creatinine \> 1.5 x upper limit of normal * Human immunodeficiency virus positive * Hepatitis A IgM antibody positive, hepatitis B surface antigen or hepatitis C antibody positive * Exposure to previous thrombopoietin (TPO) mimetics/agonists (e.g., eltrombopag,romiplostim, E5501 \[AKR-501\] or LGD-4665) within 4 weeks prior to Initial Screening * Subjects unresponsive to previous TPO mimetics/agonists (e.g., eltrombopag, romiplostim, E5501 \[AKR-501\] or LGD-4665) * Exposure to an investigative medication within 4 weeks prior to the initial Screening Visit