Combination of Lenalidomide and Rituximab in Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL-SLL)

The goal of this clinical research study is to learn if the combination of lenalidomide and rituximab can help to control CLL. The safety of this drug combination will also be studied. Lenalidomide is designed to change the body's immune system. It may also interfere with the development of tiny blood vessels that help support tumor growth. This may decrease the growth of cancer cells. Rituximab is designed to attach to cancer cells and damage them, which may cause the cells to die.

Inclusion Criteria: 1. Age \>/-18 at the time of signing of informed consent.Understand and voluntarily sign informed consent. 2. Patients with chronic lymphocytic leukemia and untreated disease with indication for treatment that are not candidates or unwilling to receive chemoimmunotherapy, or patients of any age with previously treated CLL/SLL or recurrent disease. Patients with recurrent disease are eligible if they have received prior treatment with purine analog based chemotherapy or chemoimmunotherapy or bendamustine. 3. ECOG/WHO performance status of 0-2. 4. Adequate renal function indicated by serum creatinine less or equal to 2mg/dL 5. Adequate hepatic function indicated as total bilirubin less or equal to 2mg/dL and ALT less or equal to 2 times the upper limit of normal. 6. Disease free of prior malignancies for 3 years with exception of current basal cell, squamous cell carcinoma of the skin, or carcinoma "in situ" of the cervix or breast. Patients with malignancies with indolent behavior such as prostate cancer treated with radiation or surgery can be enrolled in this study as long as they have a reasonable expectation to have been cured with the treatment modality received. 7. All study participants must be registered into the mandatory RevAssist program and be willing and able to comply with the program requirements. 8. Females of childbearing potential (FCBP) must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mlU/mL within 10-14 days and again within 24 hours prior to prescribing lenalidomide for Cycle 1. Prescriptions must be filled within 7 days and must either commit to continued abstinence from heterosexual intercourse or use 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: 1. Known sensitivity to lenalidomide or other thalidomide derivatives or rituximab. 2. Documented prolymphocytic leukemia (prolymphocytes more than 55% in the peripheral blood). 3. Known positivity for HIV or active hepatitis B or C. 4. Pregnant or breast feeding females. 5. History of tuberculosis treated within the last five years or recent exposure to tuberculosis. 6. Any serious medical condition, laboratory abnormality, or psychiatric illness that places the subject at unacceptable risk if he/she were to participate in the study. 7. Patients with a recent history of deep vein thrombosis (DVT) or pulmonary embolus (PE) in the six months prior to enrollment are not eligible for the study.