Infusion of T cells expressing CAR specific for CD19 with either CD3ζ /CD28 or CD3ζ /CD137 can induce complete tumor regressions in subsets of patients with B-lineage lymphomas, acute lymphoblastic leukemia (B-ALL), or chronic lymphocytic leukemia (CLL) [3–10]. This evidence concerns the gene CD28 and B-cell chronic lymphocytic leukemia.