CD19 and cancer: CD19-specific chimeric antigen receptor (CAR)-T cell therapy has achieved impressive progress in the treatment of hematopoietic malignancies, especially relapsed/refractory diffuse large B-cell lymphoma and relapsed/refractory B acute lymphoblastic leukemia since the US Food and Drug Administration approved the first two CD19 CAR-T cell treatments (axicabtagene ciloleucel and tisagenlecleucel) (1–3).