The present study will be conducted to evaluate the efficacy and safety of AMG531 and to determine the recommended initial dose of AMG531 on the basis of its efficacy and safety when it is administered subcutaneously (SC) to the Aplastic Anemia (AA) patients with immunosuppressive-therapy refractory thrombocytopenia and also to assess the pharmacokinetics of this product. Its efficacy and safety during the extension period beyond one year will also be evaluated.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
35
Subcutaneous, weekly injection
Korea, Republic of
Seoul, South Korea
Proportion of Subjects Achieving a Platelet Response at Week 9
The proportion of subjects achieving a platelet response at Week 9, and two-sided 95% confidence interval will be calculated. Platelet response is defined as 1) achieving absolute platelet increase of ≥ 20x10\^9/L above baseline or 2) increase to ≥ 10x10\^9/L and by at least 100% from baseline.
Time frame: At week 9
Proportion of Subjects Achieving a Platelet Response
The proportion of subjects with a platelet response in any time during the initial dose evaluation period, Week 1 through Week 12, Week 1 through Week 16, Week 1 through Week 24, Week 1 through Week 52, Week 1 through Week 104 and Week 1 through Week 156.
Time frame: Initial dose evaluation period (Week 9), Week 12, Week 16, Week 24, Week 52, Week 104, and Week 156
Proportion of Subjects Achieving Platelet Transfusion Independency
The proportion of subjects achieving platelet transfusion independency in any time during the initial dose evaluation period , Week 1 through Week 12, Week 1 through Week 16, Week 1 through Week 24, Week 1 through Week 52, Week 1 through Week 104, and Week1 through Week 156 will be calculated in the same manner as the primary variables (The number of subjects discontinued or subjects who have missing data will not be calculated). Platelet transfusion independence is defined as achieving transfusion free period of at least 8 consecutive weeks (56 days).
Time frame: Initial dose evaluation period (Week 9), Week 12, Week 16, Week 24, Week 52, Week 104, and Week 156
Proportion of Subjects Achieving Erythroid Response and/or Neutrophil Response
The proportion of subjects with erythroid response, neutrophil response and erythroid and/or neutrophil response in any time during the initial dose evaluation period, Week 1 through Week 12, Week 1 through Week 16, Week 1 through Week 24, Week 1 through Week 52, Week 1 through Week 104, and Week1 through Week 156 will be calculated in the same manner as the primary variables (The number of subjects discontinued or subjects who have missing data will not be calculated).
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Time frame: Initial dose evaluation period (Week 9), Week 12, Week 16, Week 24, Week 52, Week 104, and Week 156
Duration of Platelet Response and Time to Platelet Response
For subjects with a platelet response in any time, time to the initial platelet response and duration of platelet response will be summarized Time to the initial platelet response will be calculated as sampling date (response achieved) minus first dose date of study drug plus 1. Duration of platelet response will be calculated as the maximum of the duration of platelet response for each subject, each duration of response calculated as the date when response is disappeared minus the date when response is achieved. The censoring date is defined as the date of the last Platelet examination or EOS whichever archives first.
Time frame: Initial dose evaluation period (Week 9), Week 12, Week 16, Week 24, Week 52, Week 104, and Week 156
Proportion of Subjects Achieving Tri-lineage Responses
Tri-lineage response is defined in those achieving platelet response, erythroid response, and neutrophil response all together. The proportion of subjects with tri-lineage response will be calculated in the same manner as the primary variables. Time to tri-lineage response will be summarized in the same manner as time to platelet response. Time to tri-lineage response is defined as duration of the time from Day 1 to the date of platelet response, erythroid response or neutrophil response whichever achieves last in Visit.
Time frame: Initial dose evaluation period (Week 9), Week 12, Week 16, Week 24, Week 52, Week 104, and Week 157
Duration of Study Drug Discontinuation While Maintaining Stable Response
The longest duration of study drug discontinuation in subjects while maintaining a stable response is summarized
Time frame: Initial dose evaluation period (Week 9), Week 12, Week 16, Week 24, Week 52, Week 104, and Week 156