This is a Phase 2, multicenter, randomized, double blind, placebo controlled study designed to assess the efficacy and safety of romiplostim (formerly, AMG 531) treatment in thrombocytopenic MDS subjects. The study is composed of a 26-week placebo controlled test treatment period (romiplostim versus Placebo), a 2 to 4 week interim wash-out period, a 24-week placebo controlled extended treatment period, and a 4-week follow-up period. During the interim wash-out period, a bone marrow biopsy will be performed in the absence of growth factor to assess changes in the marrow. In the extended treatment period, safety assessments will continue and subjects will be allowed to receive any standard of care treatments for MDS.

Subjects will be followed for survival for an additional 60 months following the End of Study (EOS) visit.

• MDS
• Myelodysplastic Syndromes
• Thrombocytopenia

• Drug: Placebo
  Weekly subcutaneous dosing based on platelet count. Starting dose is at 750mcg, up to a maximum dose of 1000mcg, or reduced to a minimum of 250mcg. Placebo is supplied in a 5 mL single use glass vial as a sterile, white, preservative-free, lyophilized powder.
• Biological: Romiplostim
  Weekly subcutaneous dosing based on platelet count. Starting dose is at 750mcg, up to a maximum dose of 1000mcg, or reduced to a minimum of 250mcg . Romiplostim is supplied in a 5 mL single use glass vial as a sterile, white, preservative-free, lyophilized powder.

• Romiplostim: Experimental
  Intervention: Biological: Romiplostim
• Placebo: Placebo Comparator
  Intervention: Drug: Placebo

Inclusion Criteria:

• Diagnosis of MDS using the WHO classification
• Per MDS IPSS, low or intermediate-1 risk MDS

• The mean of the two platelet counts taken within 4 weeks prior to randomization must be:

  • ≤ 20 x 10^9/L, with no individual count >30 x 10^9/L, with or without a history of bleeding, OR
  • ≤ 50 x 10^9/L, with no individual count >60 x 10^9/L with a history of bleeding.
• Subjects must be ≥18 and ≤ 90 years of age at the time of informed consent. Subjects between 85 and 90 years of age must have been diagnosed with MDS ≤ 5 years from study start.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
• Adequate liver function, as evidenced by ALT ≤ 3 times the laboratory normal range, AST ≤ 3 times the laboratory normal range and total bilirubin ≤ 2.0 times the laboratory normal range (Adequate liver function for patients with a confirmed diagnosis of Gilbert's Disease evidenced by ALT ≤ 3 times the laboratory normal range, and AST ≤ 3 times the laboratory normal range).
• A serum creatinine concentration ≤ 2 mg/dl (≤176.8 μmol/L)
• Bone marrow biopsy and aspirate with cytogenetics within 3 months of starting first dose of investigational product
• Written Informed Consent

Exclusion Criteria:

• Have ever received any disease-modifying treatment for MDS
• Previously diagnosed with intermediate-2 or high risk MDS using the IPSS
• Prior history of leukemia, aplastic anemia, or other non-MDS related bone marrow stem cell disorder
• Prior history of hematopoietic stem cell transplantation
• Persistent peripheral blood monocytosis (≥ 3 months with an absolute monocyte count >1,000/μL)
• Prior malignancy (other than in situ cervical cancer, non-melanoma skin cancer, or in situ carcinoma) unless treated with curative intent and without evidence of disease for ≥ 3 years before randomization
• Active or uncontrolled infections
• Unstable angina, congestive heart failure (NYHA > class II), uncontrolled hypertension (diastolic >100 mmHg), uncontrolled cardiac arrhythmia, or recent (within 1 year) myocardial infarction
• History of arterial thrombosis (eg, stroke or transient ischemic attack) within the past year
• History of venous thrombosis that currently requires anti-coagulation therapy
• Received IL-11 within 4 weeks of the first dose of investigational product
• Have previously received any thrombopoietic growth factor
• Receipt of G-CSF, peg-G-CSF, or GM-CSF within 4 weeks of the first dose of investigational product
• Planned receipt of peg-G-CSF or GM-CSF after the first dose of investigational product
• Pregnant or breast feeding
• Subjects of reproductive potential who are not using adequate contraceptive precautions, in the judgment of the investigator. Amgen recommends double barrier contraception is used for all applicable patients enrolled on this study. A double barrier method is defined as two methods of contraception, for example 2 actual barrier methods, or one actual barrier method and one hormonal method.
• Subject has known sensitivity to any recombinant E coli-derived product (eg, Infergen®, Neupogen®, Somatropin, and Actimmune)
• Previously enrolled in this study
• Inability to comply with study procedures
• Subject currently is enrolled in or has not yet completed at least 30 days since ending other investigational device or drug study(s)