Eltrombopag in Combination With Rabbit Anti-thymocyte Globulin/Cyclosporine A in Naive Aplastic Anemia (AA) Subjects

Inclusion Criteria: * Japanese subjects aged \>=18 and \<71 years at the time of informed consent. Note: subjects aged \>=71 and \<75 may be eligible when clinically indicated at the discretion of the investigator by mutual agreement with Novartis medical advisor. * Diagnosed with moderate or more severe AA according to the diagnostic criteria of AA. The severity classification is: Stage I - Mild - Other than the stages below; Stage II - Moderate - At least two of the following conditions are met: Reticulocyte \<60,000/microliter, Neutrophil \<1,000/microliter, Platelet \<50,000/microliter; Stage III - Moderately severe - At least two of the following conditions are met and regular red blood cell transfusion (a need for transfusion of \>=2 units per month) is required: Reticulocyte \<60,000/microliter, Neutrophil \<1,000/microliter, Platelet \<50,000/microliter; Stage IV - Severe - At least two of the following conditions are met: Reticulocyte \<20,000/microliter, Neutrophil \<500/microliter, Platelet \<20,000/microliter; Stage V - Very severe - At least one of the following conditions is met in addition to neutrophil \<200/microliter: Reticulocyte \<20,000/microliter, Platelet \<20,000/microliter. * Subjects who are considered an indication for the treatment with rabbit ATG and CsA. * Adequate baseline organ function defined by the following criteria: Alanine aminotransferase (ALT), aspartate aminotransferase (AST)\<=3 × local upper limit of normal (ULN) Creatinine, total bilirubin, and alkaline phosphatase (ALP) \<1.5 × local ULN (total bilirubin \<2.5 × local ULN with Gilbert's Syndrome) * Eastern Cooperative Oncology Group (ECOG) Performance Status (PS): 0 or 1 * Subjects with QTcF\<450 millisecond (msec) or QTcF\<480 msec with branch block: QTc is QT interval corrected by Fridericia formula (QTcF), machine ,or manual overread. QTcF is based on single or averaged QTc value of triplicate ECG. * Subjects are able to understand and comply with protocol requirements and instructions. * Subjects have signed and dated informed consent. * Subjects who meet one of the following conditions: Male subjects who have a female partner of childbearing potential must either have a prior vasectomy or agree to use an acceptable method of contraception from time of enrollment in the study until 16 weeks after the last dose of eltrombopag (based upon the lifecycle of sperm). Female subjects of non-childbearing potential (who are physiologically unable to become pregnant) defined as: Premenopausal women with documented bilateral oophorectomy, bilateral tubal ligation, or hysterectomy; or postmenopausal women after at least 12 months of natural amenorrhea \[if uncertain, postmenopausal state should be confirmed by hematology result of follicle stimulating hormone (FSH) \>40 milli-international units (mIU)/milliliter (mL) or estradiol \<40 picogram (pg)/mL (\<140 picomoles (pmol)/L)\]. Female subjects of childbearing potential: Defined as those not meeting the definition of non-childbearing potential. Female subjects of childbearing potential must have a negative serum human chorionic gonadotropin (hCG) or urine pregnancy test within 7 days prior to the first dose of ATG/CsA. It is recommended that the pregnancy test should be performed as close as possible to the first dose of ATG/CsA. Female subjects with a positive pregnancy test must be excluded from the study. Subjects with a negative pregnancy test must use acceptable contraception including abstinence after the pregnancy test. Subjects must agree to use the acceptable contraception including abstinence from 14 days prior to the first dose of ATG/CsA until 28 days after the last dose of eltrombopag. Exclusion Criteria: * Diagnosis of congenital AA (e.g. Fanconi anemia or Dyskeratosis congenital). * Subjects who have a sibling donor with matched human leukocyte antigen (HLA) or who underwent hematopoietic stem cell transplantation (HSCT) previously. However, such subjects may be enrolled if HSCT is not indicated, or the subject does not want to undergo HSCT. * Subjects with abnormal chromosome (monosomy 7 detected by fluorescence in situ hybridization (FISH), or other aberrations detected by G-band staining). Note: Subjects with abnormal chromosome which is not adopted into the clone definition of An International System for Human Cytogenetic Nomenclature (ISCN) may be enrolled after consulting with medical monitor. * Previous ATG/ALG-based immunosuppressive therapy or steroid pulse therapy for AA. * Treatment with CsA within 6 months before administration of ATG. * Subjects with a paroxysmal nocturnal hemoglobinuria (PNH) clone size in granulocytes of \>50% by flow cytometric analysis. * Pre-existing cardiac disease (congestive heart failure New York Heart Association (NYHA) Grade II/III/IV), or arrhythmias known to involve the risk of thromboembolic events (e.g. atrial fibrillation) * Past history of thromboembolic event (including anti-phospholipid antibody syndrome) and current use of anticoagulants. * Subjects with past or current malignancy. Note : Subjects who have a history of completely resected malignant tumor and have been disease-free for 5 years are eligible. * Subjects who test positive for hepatitis B surface (HBs) antigen, hepatitis C virus (HCV) antibody, or human immunodeficiency virus (HIV) antibody at screening. * Infection not adequately responding to appropriate therapy. * Subject with liver cirrhosis * Subjects with any clinically significant severe cardiac, renal, or hepatic medical condition. * Pregnant women (a positive serum or urine pregnancy test within 7 days prior to the first dose of ATG/CsA or lactating women) Note: Female subjects who are lactating are eligible to participate if they discontinue nursing prior to the first dose of ATG/CsA and refrain from nursing until 5 days after the completion of treatment with eltrombopag. * Known hypersensitivity, intolerance or allergy to rabbit ATG, cyclosporine A, eltrombopag or any of their excipients. * Current alcohol or drug abuse. * Treatment with an investigational drug within 30 days or 5 half-lives (whichever is longer) proceeding the first dose of ATG/CsA. * Subjects who is not candidates for ATG. * Subjects who is not candidates for CsA. * History of treatment with eltrombopag, romiplostim or other thrombopoietin-receptor (TPO-R) agonists.