Inclusion Criteria:

1. Understand and voluntarily sign an informed consent form.
2. Age 18 years at the time of signing the informed consent form.
3. Able to adhere to the study visit schedule and other protocol requirements.
4. MDS patients who fulfill diagnostic criteria and classification by the IPSS Low or Int-1 categories according to cytogenetics, blood cytopenias and bone marrow blasts. See Appendix II.
5. All previous therapy such as azacitidine, decitabine, growth factors such as EPO (Procrit or Aranesp) and (Neupogen or Neulasta, Leukine, Neumega) or experimental therapy, must have been discontinued at least 4 weeks prior to treatment in this study.
6. ECOG performance status of 2 at study entry (see Appendix I).

7. Laboratory test results within these ranges:

   • Absolute neutrophil count 500/mm3
   • Platelet count 50,000 /mm3
   • Serum creatinine 2.0 mg/dL
   • Total bilirubin 1.5 mg/dL
   • AST (SGOT) and ALT (SGPT) 2 x ULN or 5 x ULN if hepatic metastases are present.
8. Females of childbearing potential (FCBP) must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mIU/mL within 10 - 14 days prior to and again within 24 hours of starting lenalidomide and must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control, one highly effective method and one additional effective method AT THE SAME TIME, at least 28 days before she starts taking lenalidomide. FCBP must also agree to ongoing pregnancy testing. Men must agree to use a latex condom during sexual contact with a FCBP even if they have had a successful vasectomy. All patients must be counseled at a minimum of every 28 days about pregnancy precautions and risks of fetal exposure. See Appendix V: Risks of Fetal Exposure, Pregnancy Testing Guidelines and Acceptable Birth Control Methods, AND also Appendix VI: Education and Counseling Guidance Document.

9. Disease free of prior malignancies for 5 years with exception of currently treated basal cell, squamous cell carcinoma of the skin, or carcinoma "insitu" of the cervix or breast

   • A female of childbearing potential is a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months).

Exclusion Criteria:

1. Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form.
2. Pregnant or breast feeding females. (Lactating females must agree not to breast feed while taking lenalidomide).
3. Any condition, including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study or confounds the ability to interpret data from the study.
4. Use of any other experimental drug or therapy within 28 days of baseline.
5. Known hypersensitivity to thalidomide.
6. The development of erythema nodosum if characterized by a desquamating rash while taking thalidomide or similar drugs.
7. Any prior use of lenalidomide.
8. Concurrent use of other anti-cancer agents or treatments.
9. Known positive for HIV or infectious hepatitis, type A, B or C.
10. Myocardial infarction within 6 months prior to enrollment, or New York Hospital Association (NYHA) Class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias, electrocardiographic evidence of acute ischemia or active conduction system abnormalities.

11. History of thromboembolic disease within the past 6 months, regardless of anticoagulation

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