B-cell maturation antigen (BCMA) is a transmembrane protein member of the tumor necrosis factor (TNF) receptor superfamily, predominantly expressed on plasma cells, including malignant myeloma cells.^1-3 Preclinical studies have shown that BCMA is essential for the survival of these cell types.^1,3 Therefore, BCMA is a promising target protein in multiple myeloma through investigational therapies such as chimeric antigen receptor (CAR) T cell therapy, bispecific T-cell engagers, and antibody drug conjugates, among others.^1,2