CD19 and B-cell chronic lymphocytic leukemia: CAR T cell therapies on the cell surface transmembrane protein of B cells’ CD19, the most studied target [57], have emerged as a promising tool in the management of hematologic malignancies [57,58] (acute lymphoblastic leukemia, diffuse large B cell lymphoma, chronic lymphocytic leukemia, and B cell non-Hodgkin lymphomas) (Figure 1).