The purpose of this study is to determine if lenalidomide (Revlimid®) is safe and effective as a maintenance therapy at improving further the quality of the response you achieved with your last therapy and at prolonging the duration of your response. This study will compare the effects (good and bad) of lenalidomide with the dummy drug.

• Drug: Lenalidomide
  Lenalidomide capsules given orally on days 1-28 of a 28 day cycle
  Other Name: Revlimid
• Drug: Placebo
  Placebo capsules given orally on days 1 - 28 of a 28 day cycle

• 1: Experimental
  Lenalidomide po qd on days 1-28 of a 28 day cycle
  Intervention: Drug: Lenalidomide
• 2: Placebo Comparator
  Placebo capsules given orally on days 1-28 of a 28 day cycle
  Intervention: Drug: Placebo

Inclusion Criteria:

1. Must sign an informed consent form.
2. Age ≥ 18 years
3. Must be able to adhere to the study visit schedule and other protocol requirements.
4. Must have a documented diagnosis of B-cell CLL.
5. Must have been treated with a purine analog-containing regimen in the first and/or second line induction therapy.
6. Must have achieved a minimum of partial response following completion of second-line induction therapy.
7. Must have an Eastern Cooperative Oncology Group (ECOG) performance status score of ≤2.
8. Must agree to follow pregnancy precautions as required by the protocol.
9. Must agree to receive counseling related to teratogenic and other risks of lenalidomide.
10. Must agree not to donate blood, eggs or sperm as defined by the protocol

Exclusion Criteria:

1. Any medical condition, that would prevent the subject from signing the informed consent form.
2. Active infections requiring systemic antibiotics.
3. Systemic infection that has not resolved > 2 months prior to initiating lenalidomide
4. Autologous or allogeneic bone marrow transplant as second line therapy.
5. Pregnant or lactating females.
6. Participation in any clinical study or having taken any investigational therapy within 28 days.
7. Known presence of alcohol and/or drug abuse.
8. Central nervous system (CNS) involvement.

9. Prior history of malignancies, other than CLL, unless the subject has been free of the disease for ≥3 years. Exceptions include the following:

   • Basal cell carcinoma of the skin
   • Squamous cell carcinoma of the skin
   • Carcinoma in situ of the cervix
   • Carcinoma in situ of the breast
   • Incidental histologic finding of prostate cancer (TNM stage of T1a or T1b)
10. History of renal failure requiring dialysis.
11. Known Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV) and/or Hepatitis C Virus (HCV) infection.
12. Prior therapy with lenalidomide.
13. Presence of specific hematology and/or chemistry abnormalities
14. Severe rash due to prior thalidomide treatment
15. Uncontrolled hyperthyroidism or hypothyroidism
16. Venous thromboembolism within one year
17. ≥ Grade-2 neuropathy
18. Uncontrolled autoimmune hemolytic anemia or thrombocytopenia