A series of remarkable clinical results obtained a decade ago in patients with refractory B-cell malignancies, including non-Hodgkin lymphoma (NHL), chronic lymphocytic leukemia (CLL), and acute lymphocytic leukemia (ALL), fostered worldwide interest in CAR T cell engineering and resulted in the regulatory approval of CD19 CAR therapies within a few years (6–12). This evidence concerns the gene CD19 and B-cell chronic lymphocytic leukemia.