Lenalidomide + Plerixafor in Previously Treated Chronic Lymphocytic Leukemia (CLL)

"1. Lenalidomide 5mg by mouth (PO) daily beginning cycle 1 day 1.~2. Stage 1: increase by 2.5mg every 7 days to a maximum dose of 10mg.~3. Stage 2: plerixafor will be added after 28 days of 10mg dose maintenance and white blood cell count (WBC) \<100.0 x 109 / L.~4. Dose cohorts of escalating subcutaneous (SC) thrice weekly plerixafor with continuous 10mg lenalidomide:~ * Cohort 1: 0.24 mg/kg~ * Cohort 2: 0.32 mg/kg~ * Cohort 3: 0.42 mg/kg~ * Cohort 4: 0.54 mg/kg~5. Stage 3: Rituximab 375mg/m2 will be added on day 1 of cycles 5-12, day 1 of combination therapy for subjects with PR.~6. Subjects will then continue single agent lenalidomide until disease progression."