Study of Bendamustine/Rituxan Induction Chemotherapy With Revlimid Maintenance for Relapsed/Refractory CLL and SLL

Inclusion Criteria: * Histologically confirmed,CLL/SLL, documented relapsed or refractory disease after at least one prior chemotherapy regimen. * In cases of SLL, patients must have at least one bidimensionally measurable lesion at least ≥1.5 cm measured in one dimension. * ECOG performance status of 0-2 at study entry * Laboratory test results within these ranges: ANC \<=1500/μL, Platelet count \<= 100,000/μL. Patients with ANC \<1500/μL or plt \<100,000/μL with splenomegaly or extensive bone marrow involvement as the etiology for their cytopenias are eligible. * creatinine clearance of \>60 mL/min as determined by the Cockcroft-Gault calculation. * Total bilirubin \<= 2X upper limit laboratory normal (ULN). Patients with non-clinically significant elevations of bilirubin due to Gilbert's disease are not required to meet these criteria. * Serum transaminases AST (SGOT) and ALT (SGPT) \<=5x ULN, Serum alkaline phosphatase ≤5 X ULN. * Disease free of prior malignancies for ≥ 2 years with the exception of basal or squamous cell skin carcinoma, carcinoma "in situ" of the breast or cervix, or localized prostate cancer (treated definitively with hormone therapy, radiotherapy, or surgery). * Patients may have received prior therapy with bendamustine or lenalidomide, but must not have disease that is refractory to bendamustine or lenalidomide. * Prior therapy with rituximab is permitted, even in the setting of rituximab refractory disease. Exclusion Criteria: * Has received \>5 lines of prior therapy for their disease. Re-treatment with an identical regimen does not count as a new regimen. * Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form or comply with the protocol treatment. * Pregnant or breast feeding females. Lactating females must agree not to breast feed while taking lenalidomide. * Prior history or current evidence of central nervous system or leptomeningeal involvement. * Use of any other experimental drug or therapy within 28 days of baseline. * Known hypersensitivity to thalidomide. * The development of erythema nodosum if characterized by a desquamating rash while taking thalidomide or similar drugs. * Known to be positive for HIV or infectious hepatitis, type B or C.