Genetic defects of gamma-secretase genes in a multiple myeloma patient with high and dysregulated BCMA surface density: A case report

Soluble B-cell maturation antigen in multiple myeloma

B-cell maturation antigen (BCMA) has emerged as a promising immunotherapeutic target in multiple myeloma (MM) management, with the successive approval of antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T-cell therapies directed to this membrane receptor. Soluble BCMA (sBCMA), a truncated version produced through gamma-secretase cleavage, can be quantified in serum/plasma samples from patients with MM via electrochemiluminescence, fluorescence, or enzyme-linked immunosorbent assays, as well as through mass spectrometry-based proteomics. Besides its short serum half-life and independence from kidney function, sBCMA represents a reliable and convenient tool for MM monitoring in patients with nonsecretory or oligosecretory disease. Numerous studies have suggested a potential utility of this bioanalyte in the risk stratification of premalignant plasma cell disorders, diagnosis and prognostication of MM, and response evaluation following anti-myeloma therapies. In short, sBCMA might be the "Swiss army knife" of MM laboratory testing, but is it ready for prime time?

Unveiling the link between genetic alterations in gamma secretase and BCMA surface density in multiple myeloma

Cattaneo et al. report a unique case of a multiple myeloma patient with elevated B-cell maturation antigen (BCMA) surface density, potentially due to genetic alterations in the gamma-secretase protease complex-responsible for BCMA cleavage from plasma cells. No mutations in the BCMA gene were detected, but there was partial deletion of PSEN1 and amplification of PSEN2 (components of the gamma-secretase complex), which may explain the lack of response to the gamma-secretase inhibitor DAPT. This case, along with recent published literature, underscores the significance of gamma secretase in modulating BCMA density and the potential impact of its genetic alterations. Commentary on: Cattaneo et al. Genetic defects of gamma-secretase genes in a multiple myeloma patient with high and dysregulated BCMA surface density: A case report. Br J Haematol 2024;204:571-575.