Determination of Safe and Effective Dose of Romiplostim (AMG 531) in Subjects With Myelodysplastic Syndrome (MDS)Receiving Hypomethylating Agents

Inclusion Criteria: - Diagnosis of MDS by bone marrow biopsy based on the World Health Organization (WHO) classification - Low, Intermediate-1 or Intermediate-2 risk category MDS using the IPSS (International Prognostic Scoring System) - Planned to receive either azacytidine 75 mg/m2 by subcutaneous administration each day for 7 days or decitabine 20 mg/m2 by intravenous administration each day for 5 days for at least 4 cycles Exclusion Criteria: * Prior exposure to \>3 cycles hypomethylating agents * Prior history of leukemia or aplastic anemia * Prior history of bone marrow transplantation * Prior malignancy (other than in situ cervical cancer or basal cell cancer of the skin) unless treated with curative intent and without evidence of disease for ³ 3 years before randomization * Active or uncontrolled infections * Unstable angina, congestive heart failure \[NYHA (New York Heart Association) \> class II\], 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) in the past year * History of venous thrombosis that currently requires anti-coagulation therapy * Received IL-11 within 4 weeks of screening * Less than 4 weeks since receipt of any therapeutic drug or device that is not FDA approved for any indication * Have previously received any other thrombopoietic growth factor