Definition

A T-cell engager (TCE) targeting the tumor-associated antigens (TAAs) B-cell maturation antigen (BCMA; tumor necrosis factor receptor superfamily member 17; TNFRSF17) and G-protein coupled receptor family C group 5 member D (GPRC5D), and the T-cell surface antigen CD3, with potential antineoplastic activity. Upon administration, GPRC5D/BCMA/CD3-targeting TCE IBI3003 binds to CD3 expressed on T cells, and BCMA and GPRC5D expressed on tumor cells. This results in the cross-linking of T-cells and tumor cells, and induces a potent cytotoxic T-lymphocyte (CTL) response against BCMA- and GPRC5D-expressing tumor cells. BCMA, a receptor for both a proliferation-inducing ligand (APRIL) and B-cell activating factor (BAFF), is a member of the tumor necrosis factor receptor superfamily (TNFRSF). BCMA, found on the surfaces of plasma cells and overexpressed on malignant plasma cells, plays a key role in plasma cell proliferation and survival. GPRC5D is overexpressed in certain malignancies, such as multiple myeloma, while minimally expressed in normal, healthy cells. It plays a key role in tumor cell proliferation.