Phase I/II Open-label Study Evaluating The Safety And Efficacy of Concomitant Administration of Anti-CD19 CAR T-cell Therapy and Lenalidomide in Refractory/Relapsed Chronic Lymphocytic Leukemia Patients.

Inclusion Criteria:

* Documented CD19+ CLL or SLL
* Patients must have failed at least 1 prior regimen
* Patients must be currently receiving ibrutinib for at least 3 months prior to enrollment in the study and:
* Not experiencing any ≥ grade 2 non-hematologic ibrutinib-related toxicity
* ECOG Performance status 0 or 1
* 18 years of age and older
* Adequate organ system function including:

Creatinine \< 1.6 mg/dl ALT/AST \< 3x upper limit of normal Total Bilirubin \<2.0 mg/dl with the exception of patients with Gilbert syndrome; patients with Gilbert syndrome may be included if their total bilirubin is ≥ 3.0 x ULN and direct bilirubin ≤ 1.5 x ULN.

* Have no active GVHD and require no immunosuppression
* Are more than 6 months from transplant
* No contraindications for leukapheresis
* Left Ventricular Ejection fraction \>50%
* Gives informed consent

Exclusion Criteria:

* CLL patients with known or suspected transformed disease (i.e. Richter's transformation).
* Pregnant or lactating women.
* Uncontrolled active infection.
* Active hepatitis B or hepatitis C infection.
* Concurrent use of systemic steroids or chronic use of immunosuppressant medications.
* Any uncontrolled active medical disorder
* HIV infection.
* Patients with active CNS involvement with malignancy.
* Class III/IV cardiovascular disability according to the New York Heart Association Classification.
* Subjects with clinically apparent arrhythmia or arrhythmias who are not stable