CD19 CAR T cells have been extensively applied in clinical trials to treat B cell acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), diffuse large B cell lymphoma (DLBCL), B cell non-Hodgkin lymphoma (B-NHL), and mantle-cell lymphoma (MCL). This evidence concerns the gene CD19 and diffuse large B-cell lymphoma.