Aplastic Anemia

To evaluate the hematological responses based on the response assessment criteria when AMG531 is subcutaneous (SC)-administered with anti-human thymocyte immunoglobulin (ATG) + ciclosporin A (CsA) therapy for 6 months in patients with aplastic anemia (AA) who were previously untreated with immunosuppressive therapy.

AMG531

Romiplostim

injection

250 microgram

Primary Outcome Measures :
Achievement of complete response (CR) or partial response (PR) [ Time Frame: 27 weeks post-dose ]

Secondary Outcome Measures :
Achievement of CR or PR [ Time Frame: Week 14 ]
Achievement of CR [ Time Frame: Weeks 14 and 27 ]
The time to CR or PR [ Time Frame: Each time point evaluated weekly until Week 27 ]
Reduction or independence of platelet and/or erythrocyte transfusion [ Time Frame: Week 27 ]
Change from baseline in platelet count (/µL) [ Time Frame: Each time point evaluated weekly until Week 27 ]
Change from baseline in hemoglobin (Hb) concentration (g/dL) [ Time Frame: Each time point evaluated weekly until Week 27 ]
Change from baseline in neutrophil count (/µL) [ Time Frame: Each time point evaluated weekly until Week 27 ]
Change from baseline in reticulocyte count (/µL) [ Time Frame: Each time point evaluated weekly until Week 27 ]

Inclusion Criteria:

Voluntary signed informed consent to participate in the study;
A diagnosis of AA confirmed by blood and bone-marrow examinations, etc.;
Considered to require new treatment with ATG and CsA provided that NSAA must be platelet or erythrocyte transfusion-dependent.
An Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0 to 1at screening

Exclusion Criteria:

Previously treated with ATG, CsA, or Alemtuzumab;
Diagnosed as having congenital AA (Fanconi anemia, congenital dyskeratosis, etc.);
Diagnosed as having AML or chronic myelomonocytic leukemia;
Concurrent thrombocytopenia of other etiologies (e.g., MDS, ITP, cirrhosis);
Concurrent active infection not adequately responding to appropriate therapy;
Concurrent clinically significant illness(es) items which are deemed by the Investigator to be likely to affect the study conduct and assessments.
Having active malignancies, or having a history of treatment of malignancies within 5 years prior to informed consent.
Concurrent PNH
Having Grade 2 or higher bone marrow reticulin based on Bone Marrow Pathology (2nd edition) ;
History of chromosome aberrations discovered in bone marrow cells.
Having blast cells > 2% in bone marrow;
Positive for anti-human immunodeficiency virus (HIV) antibody;
Receiving prophylactic or therapeutic treatment for hepatitis type B
Positive for hepatitis C virus (HCV) antibody, and HCV infection being confirmed
Planned hematopoietic stem cell transplantation during the study;
Systemic treatment with any of the following medication for the treatment of AA within 4 weeks before Day 1, however, excluding their use as premedication:
Anabolic steroids
Corticosteroids;
Pregnant or breastfeeding women, or women willing to become pregnant;
Other conditions unsuitable for participation in the study in the opinion of the Investigator.