Inclusion Criteria

- INCLUSION CRITERIA:

- Age greater than or equal to 18 years old

- Unequivocal diagnosis of MDS (including chronic myelomonocytic leukemia- CMML)
according to WHO criteria with IPSS risk categorization for MDS subjects of
intermediate-2 to high confirmed by bone marrow evaluation within 30 days prior to
study enrollment

OR

Unequivocal diagnosis of AML according to WHO criteria to include secondary and relapsed
or refractory disease confirmed by bone marrow evaluation within 30 days prior to study
enrollment

- ECOG Performance Status less than or equal to 2

- Must have failed at least one prior therapy before study enrollment

- Ability to comprehend the investigational nature of the study and provide informed
consent

- All study participants must be registered into the mandatory RevAssist program, and
be willing and able to comply with the requirements of RevAssist

- Females of childbearing potential (FCBP)(Cross) must have a negative serum or urine
pregnancy test with a sensitivity of at least 50 milli-International units per
milliliter within 10 - 14 days and again within 24 hours prior to prescribing
lenalidomide for Cycle 1 (prescriptions must be filled within 7 days as required by
RevAssist) 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.

EXCLUSION CRITERIA:

- Prior Allogeneic Stem Cell Transplant

- Diagnosis of acute promyelocytic leukemia

- Diagnosis of atypical chronic myeloid leukemia BCR-ABL1 negative, juvenile
myelomonocytic leukemia, yelodysplastic/myeloproliferative neoplasm unclassifiable)

- Prior therapy with clofarabine at any dose

- Prior therapy with lenalidomide at doses greater than or equal to 25 milligrams daily

- Clinically significant active infection not responding adequately to therapy

- HIV Positive

- Uncontrolled concurrent hepatic, renal, cardiac, pulmonary, neurologic, infectious,
or metabolic disease of such severity, which in the opinion of the PI, would preclude
the subjects's ability to tolerate protocol therapy

- Ejection fraction less than 40% by Echocardiogram or MUGA

- Calculated creatinine clearance less 60 milliliters per minute

- Serum bilirubin greater than 1.5 times upper limit of normal

- Aspartate aminotransferase (AST) or Alanine aminotransferase (ALT) greater than 3
times upper limit normal

- Decreased oxygen saturation at rest (e.g. pulse oximeter less than 88% or PaO2 less
than or equal to 55 millimeters of mercury)

- Patients with any condition that prevents their ability to swallow and retain
lenalidomide tablets

- Severe psychiatric illness or complex social situations that would limit the
patient's ability to tolerate and/or comply with study requirements

- Current pregnancy or breastfeeding