This study is a multicenter, single-arm, open-label study of oral CC-5013 monotherapy administered to red blood cell (RBC) transfusion-dependent subjects with low- or intermediate-1-risk MDS associated with a del (5q31-33) cytogenetic abnormality. Screening procedures will take place within 28 days of the first day of CC-5013 treatment. Subjects will receive CC-5013 in 28-day cycles for up to 6 cycles, or until bone marrow disease progression or progression/relapse following erythroid hematologic improvement (Appendix I) is documented. Study visits will occur every cycle (every 28 days) and laboratory monitoring to assess hematological parameters will occur every 14 days. Safety and efficacy assessments to be performed during the study are outlined in the Schedule of Study Assessments

Inclusion Criteria:

• Must understand and voluntarily sign an informed consent form
• Age 18 years or older at the time of signing the informed consent
• Must be able to adhere to the study visit schedule and other protocol requirements.
• Diagnosis of low or intermediate-1-risk IPSS (Appendix III) MDS without an abnormality of chromosome 5 involving a deletion between bands q31 and q33.
• Red blood cell (RBC) transfusion-dependent anemia defined as having received greater than or equal to 2 units of RBCs within 8 weeks of the first day of study drug treatment.
• Eastern Cooperative Oncology Group (ECOG) (Appendix IV) performance status score of 0,1, or 2.
• Women of childbearing potential (WCBP) must have a negative serum or urine pregnancy test within 7 days of starting study drug.
• Sexually active WCBP must agree to use adequate contraceptive methods (oral, injectable, or implantable hormonal contraceptive; tubal ligation; intra-uterine device; barrier contraceptive with spermicide; or vasectomized partner) while on study drug.
• WCBP must agree to have pregnancy tests every 4 weeks while on study drug.

Exclusion Criteria:

• Pregnant or lactating females
• Prior therapy with CC-5013.
• An abnormality of chromosome 5 involving a deletion between bands q31 and q33.
• Lab Abnormality: Absolute neutrophil count (ANC) <500 cell/mm3 (0.5 x 109/L)
• Lab Abnormality: Platelet count <50,000/mm3 (50 x 109/L)
• Lab Abnormality: Serum creatinine >2.5 mg/dL (221 mmol/L)
• Lab Abnormality: Serum total bilirubin >2.0 mg/dL (34 mmol/L)
• Prior greater than or equal to grade 3 National Cancer Institute (NCI) Common Toxicity Criteria (CTC) (Appendix VI) allergic reaction/hypersensitivity to thalidomide.
• Clinically significant anemia due to factors such as iron, B12 or folate deficiencies, autoimmune or hereditary hemolysis or gastrointestinal bleeding
• If a marrow aspirate is not evaluable for storage iron, transferrin saturation must be > 20% and serum ferritin not less than 50 ng/mL
• Use of hematopoietic growth factors within 7 days of the first day of study drug treatment.
• Prior greater than or equal to grade 3 NCI CTC (Appendix VI) rash or any desquamation (blistering) while taking thalidomide.
• Chronic use (>2 weeks) of greater than physiologic doses of a corticosteroid agent (dose equivalent to >10 mg/day of prednisone) within 28 days of the first day of study drug treatment.
• Use of experimental or standard drugs (i.e. chemotherapeutic, immunosuppressive, and cytoprotective agents) for the treatment of MDS within 28 days of the first day of study drug treatment.
• Prior history of malignancy other than MDS (except basal cell or squamous cell carcinoma or carcinoma in situ of the cervix or breast) unless the subject has been free of disease for greater than or equal to 3 years.
• Use of any other experimental therapy within 28 days of the first day of study drug treatment.