CD19 is a B-lineage-specific transmembrane glycoprotein, the expression of which is maintained on more than 95% B-cell malignancies. This strict lineage restriction makes CD19 an ideal target for immune therapies using chimeric antigen receptors (CARs).CD19 is nearly ubiquitously expressed on B-lymphocytes and in B-cell malignancies. The anti-CD19 monoclonal antibody tafasitamab, paired with the immunomodulator lenalidomide, mediates antibody-dependent cellular toxicity and phagocytosis; the antibody-drug conjugate loncastuximab tesirine delivers the DNA cross-linking agent tesirine via CD19 binding and internalization; and CD19-directed chimeric antigen receptor T-cell therapy (CAR-T) products are engineered from autologous T cells.