CD19 and cancer: CAR-T therapy has been shown to be effective in achieving clinical response in cancer patients initially in chronic lymphocytic leukemia and follicular lymphoma with the first CD19-targeting CAR-T cell therapy eventually approved by the Food and Drug Administration (FDA) in the U.S.A. in 2017 for the treatment of pediatric and young adult B-cell acute lymphoblastic leukemia (6–8).