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). The gene discussed is CD19; the disease is acute lymphoblastic leukemia.