A Phase 3, Multicenter, Placebo-Controlled Study to Compare the Efficacy and Safety of Lenalidomide vs. Placebo in Subjects With Transfusion Dependent Anemia Due to Low or Intermediate Risk MDS and Unresponsive to ESA Therapies

Inclusion Criteria:

- 18 years or older

- Diagnosis of low or intermediate-1 risk MDS with any chromosome karyotype except del
5q[31]

- Anemia that requires red blood cell transfusions

- Resistant to erythropoiesis stimulating agents (ESAs) or blood erythropoietin level >
500 mU/mL

- ECOG Performance Status ≤ 2

- Must agree to follow pregnancy precautions as required by the protocol.

- Must agree to receive counseling related to teratogenic and other risks of
lenalidomide

- Must agree not to donate blood or semen

- Must be willing to consent to two or more bone marrow aspirate procedures to be
completed during study

Exclusion Criteria:

- Subjects previously receiving immunomodulating or immunosuppressive agents, or
epigenetic or DNA modulation agents

- Allergic reaction to thalidomide

- Renal insufficiency (CrC1<40 mL/min by Cockroft-Gault method)

- Prior history of cancer, other than MDS, unless the subject has been free of the
disease for ≥ 5 years. (Basal cell carcinoma of the skin, Carcinoma in situ of the
cervix, or stage T1a or T1b prostate cancer is allowed)

- Absolute neutrophil count < 500/uL

- Platelets < 50,000/uL

- AST or ALT > 3X upper limit of normal

- Uncontrolled hyperthyroidism or hypothyroidism

- Significant neuropathy

- Prior stem cell transplantation

- Anemia due to reasons other than MDS

- History of deep venous thrombosis (DVT) or pulmonary embolus (PE) within past 3 years

- Significant active cardiac disease within the past 6 months

- Known HIV infection; known Hepatitis C infection or active Hepatitis B infection