B-lymphocyte antigen CD19 and T-cell surface glycoprotein CD3 epsilon chain (CD19/CD3)

CD19/CD3 represents a bispecific therapeutic target complex consisting of the B-lymphocyte antigen CD19 and the T-cell receptor-associated CD3 epsilon chain (UniProt: P15391, P07766). CD19 is a transmembrane protein expressed throughout B-cell development, from the pro-B stage until differentiation into plasma cells, making it a highly specific marker for B-lineage cells (PubMed: 15546383). CD3 is a critical co-receptor involved in the activation of both cytotoxic T-cells and T-helper cells. This dual target is the foundation for Bispecific T-cell Engager (BiTE) technology, which physically bridges malignant B-cells with cytotoxic T-cells to induce tumor cell lysis. The most prominent drug targeting this pair is blinatumomab, which is used to treat B-cell precursor acute lymphoblastic leukemia (ALL) and has shown significant efficacy in achieving minimal residual disease (MRD) negativity (FDA Label: Blincyto). By bypassing the requirement for major histocompatibility complex (MHC) class I recognition, CD19/CD3-directed therapies can effectively redirect the patient's own immune system to eliminate cancerous B-cells. However, the potent and rapid activation of the immune system associated with this target often results in severe adverse effects, most notably cytokine release syndrome (CRS) and neurotoxicity (StatPearls: Blinatumomab).

Other names

CD19/CD3eB4/T3ECD19-CD3 complexBispecific T-cell engager target

Bispecific T-cell engagement (BiTE) that bridges CD19-expressing B-cells with CD3-expressing T-cells, leading to MHC-independent T-cell activation and subsequent lysis of the target B-cell (PubMed: 25468732).