CD19 and B-cell chronic lymphocytic leukemia: CAR T cells specific for the CD19 antigen have proven to be clinically efficacious, with recent clinical trials treating a range of blood cancers including B cell acute lymphoblastic leukemia (B-ALL), diffuse large B-cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL), achieving up to 90% complete responses in some trials [10–12].