CD19 and diffuse large B-cell lymphoma: Especially for the treatment of hematological diseases, such as acute B-cell leukemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL), cellular therapy with chimeric antigen receptor (CAR)-engineered autologous T cells has achieved considerable responses, which has led to approval of two CD19-targeted CAR-T cell products in the US and Europe.