A Multicenter, Single-arm, Open-label Study of the Efficacy and Safety of Lenalidomide Monotherapy in Red Blood Cell Transfusion-dependent Subjects With Myelodysplastic Syndromes Associated With a Del(5q) Cytogenetic Abnormality.

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 International Prognostic Scoring System
(IPSS) Myelodysplastic Syndromes (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) 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 lenalidomide.

- An abnormality of chromosome 5 involving a deletion between bands q31 and q33.

- Lab Abnormality: Absolute neutrophil count (ANC) <500 cell/mm^3 (0.5*10^9/L)

- Lab Abnormality: Platelet count <50,000/mm^3 (50*10^9/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) 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 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.