Anti-Human GPRC5D/CD3 Monoclonal Antibody (Talquetamab)

GPRC5D (G protein-coupled receptor class C group 5 member D) is a ~40 kDa seven-transmembrane orphan receptor whose natural ligand remains unknown; it carries a very short extracellular N-terminus, forms homodimers via TM4–TM4/5 contacts, and is transcriptionally induced by retinoic acid. In healthy tissues expression is tightly restricted—highest in hair follicle and nail bed keratinocytes where it modulates hard-keratin gene expression—while in malignancy it is markedly up-regulated on the surface of multiple-myeloma plasma cells, rendering it a tumor-selective antigen now exploited by bispecific antibodies (talquetamab, LBL-034) and CAR-T cells that redirect T-cell cytotoxicity against GPRC5D-positive myeloma cells, with minimal on-target toxicity to normal tissues .