| Description : |
B-cell maturation antigen (BCMA), also known as CD269 or TNFRSF17, is a transmembrane glycoprotein that serves as a critical regulator of B cell development and function. It belongs to the tumor necrosis factor receptor (TNFR) superfamily and is predominantly expressed on plasma cells and a subset of late-stage B cells. BCMA’s primary biological role is to promote the survival, differentiation, and long-term maintenance of antibody-producing plasma cells by mediating signals from specific ligands in the TNF family.
Structurally, BCMA is a type I transmembrane protein consisting of an extracellular cysteine-rich domain responsible for ligand binding, a single transmembrane region, and a short cytoplasmic tail that interacts with intracellular signaling molecules. The cytoplasmic domain lacks death domains but recruits TRAF (TNF receptor-associated factor) adaptor proteins to activate downstream pathways such as NF-κB and MAPK. These signaling cascades enhance plasma cell survival and immunoglobulin production, contributing to humoral immunity maintenance. Soluble BCMA, generated through proteolytic cleavage by γ-secretase, can act as a decoy receptor to regulate ligand availability in the serum.
BCMA binds two main ligands: B-cell activating factor (BAFF, also known as BLyS) and a proliferation-inducing ligand (APRIL). Both ligands are produced by myeloid and stromal cells and support B cell homeostasis. Among these, APRIL binds BCMA with higher affinity and is the primary mediator of BCMA-dependent signaling in plasma cells. The BAFF/APRIL–BCMA axis thus serves as a crucial checkpoint for sustained antibody production and plasma cell survival.
In disease contexts, BCMA is strongly implicated in multiple myeloma (MM) and certain B-cell lymphomas. Its selective overexpression on malignant plasma cells makes it an important diagnostic marker and a therapeutic target. BCMA-directed treatments have revolutionized therapy for multiple myeloma, including antibody-drug conjugates (e.g., belantamab mafodotin), bispecific T cell engagers (e.g., teclistamab, elranatamab), and CAR-T cell therapies (e.g., idecabtagene vicleucel, ciltacabtagene autoleucel). These agents exploit BCMA’s restricted expression pattern to deliver targeted cytotoxicity, leading to durable responses in refractory disease. Consequently, BCMA has emerged as a prototypical target in the development of next-generation immunotherapies for hematologic malignancies. |
