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

A Randomized, Double Blind, Placebo Controlled Study Evaluating the Efficacy and Safety of Romiplostim (AMG 531) Treatment of Subjects With Low or Intermediate Risk Myelodysplastic Syndrome (MDS) Receiving Hypomethylating Agents

The purpose of this study is to evaluate the effect of Romiplostim (AMG 531) on the incidence of clinically significant thrombocytopenic events (grade 3 or 4 and/or receipt of platelet transfusions) in subjects with low or intermediate risk Myelodysplastic Syndrome (MDS) receiving hypomethylating agents. It is hypothesized that Romiplostim administration, at the appropriate dose and schedule, will result in reduction in the incidence of clinically significant thrombocytopenic events in low or intermediate risk MDS subjects 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