Inclusion Criteria:

   - Relapsed or refractory acute lymphoblastic leukemia (ALL) with > 10% bone marrow or
   peripheral blood blasts per WHO-criteria. Refractory define as failure to achieve CR
   after prior therapy.

   - Previously untreated patients > 60, if not candidates for standard induction

   - Age ≥ 18

   - Not a candidate for curative treatment regimens

   - Unwilling or unable to receive conventional chemotherapy

   - ECOG performance status ≤ 2

   - Life expectancy > 2 months

   - Registered to in RevAssist restricted distribution program, and willing and able to
   comply with the program requirement

   - Females of childbearing potential (FCBP):

      - Must have a negative serum or urine pregnancy test (sensitivity of at least 50
      mIU/mL) 10 to 14 days prior to study enrollment and within 24 hours prior to
      prescribing lenalidomide

      - Must either commit to continued abstinence from heterosexual intercourse or begin
      two acceptable methods of birth control

      - Agree to ongoing pregnancy testing

   - Men must agree to use a latex condom during sexual contact with a FCBP

   - Able to adhere to the study visit schedule and other protocol requirements

   - Willing and able to understand and voluntarily sign a written informed consent

Exclusion Criteria:

   - Prior therapy with lenalidomide

   - History of intolerance to thalidomide including development of erythema nodosum while
   taking thalidomide or similar drugs

   - Advanced malignant hepatic tumors.

   - Concomitant treatment with other anti-neoplastic agents (exception hydroxyurea)

   - Anti-neoplastic treatment less than 4 weeks prior to enrollment (exception
   hydroxyurea)

   - Use of any other experimental drug or therapy within 14 days of baseline

   - Inability to swallow or absorb drug

   - Active opportunistic infection or treatment for opportunistic infection within 4 weeks
   of first dose of study drug

   - New York Heart Association Class III or IV heart failure

   - Unstable angina pectoris

   - Cardiac arrhythmias with rapid ventricular response (heart rate > 100 beats/minute)

   - Uncontrolled psychiatric illness that would limit compliance with requirements

   - Known HIV infection

   - Known active hepatitis B virus (HBV) (exception seropositivity due to HBV vaccine not
   considered active HBV)

   - Known hepatitis C virus (HCV) infection

   - Pregnant

   - Lactating females must agree not to breastfeed while taking lenalidomide

   - Other medical or psychiatric illness or organ dysfunction or laboratory abnormality
   which in the opinion of the investigator would compromise the patient's safety or
   interfere with data interpretation

   - Creatinine ≥ 1.5 mg/dL

   - Creatinine clearance ≤ 60 mL/min.

   - Total bilirubin > 1.5 x institutional upper limit of normal (ULN) (exception
   documented Gilbert's syndrome)

   - AST and ALT > 3 x institutional ULN