BCMAexpressing

BCMAexpressing refers to cells that express B-cell maturation antigen (BCMA), a type II transmembrane receptor encoded by the TNFRSF17 gene. BCMA belongs to the tumor necrosis factor receptor superfamily and mediates signaling that promotes plasma cell survival and maturation through NF-κB and other pathways. In humans, BCMA expression is largely restricted to mature B-lineage cells, including plasmablasts and plasma cells, with minimal expression on naive B cells or nonhematopoietic tissues. In healthy tissues, BCMA is most abundant in bone marrow plasma cells and in a subset of activated B cells during germinal center reactions.

In malignant contexts, BCMA is frequently overexpressed on malignant plasma cells, such as in multiple myeloma and certain plasmacytomas, making it a useful biomarker and therapeutic target. The level of BCMA expression can vary between patients and among lesions within the same patient and can change over time or in response to therapy. BCMA expression is typically assessed by flow cytometry or immunohistochemistry on bone marrow or tumor biopsy samples, and soluble BCMA can be measured in serum as a pharmacodynamic or prognostic marker.

Therapies directed at BCMA include antibody-drug conjugates, bispecific T-cell engaging antibodies, and chimeric antigen receptor (CAR) T-cell therapies. The efficacy of BCMA-targeted treatments generally correlates with cell-surface BCMA expression, though some effectiveness has been observed with lower levels of expression. Because BCMA can be shed from the cell surface by gamma-secretase, combination strategies to boost BCMA density are under investigation.