Study of Lenalidomide to Evaluate Safety and Efficacy in Patients With Relapsed or Refractory Chronic Lymphocytic Leukemia

Inclusion Criteria:

* Age ≥ 18 years at the time of signing the informed consent form
* Must be able to adhere to the study visit schedule and other protocol requirements
* Must have a documented diagnosis of B-cell CLL
* Must be relapsed or refractory to at least 1 regimen for treatment of CLL. At least one of the prior treatments must have included a purine analog-based or bendamustine-based regimen
* Must have an Eastern Cooperative Oncology Group (ECOG) performance status score of ≤ 2.

Exclusion Criteria:

* Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form
* Active infections requiring systemic antibiotics
* Systemic treatment for B-cell CLL within 28 days of initiation of lenalidomide treatment
* Alemtuzumab therapy within 120 days of initiating lenalidomide treatment
* Prior therapy with lenalidomide
* History of grade 4 rash due to prior thalidomide treatment
* Planned autologous or allogeneic bone marrow transplantation
* Central nervous system (CNS) involvement as documented by spinal fluid cytology or imaging.
* Uncontrolled hyperthyroidism or hypothyroidism
* Venous thromboembolism within 12 months
* ≥ Grade 2 neuropathy
* Uncontrolled autoimmune hemolytic anemia or thrombocytopenia
* Disease transformation \[i.e. Richter's Syndrome (lymphomas) or prolymphocytic leukemia\]
* Participation in any clinical study or having taken any investigational therapy within 28 days prior to initiating lenalidomide therapy