Serum B-Cell Maturation Antigen as a Biomarker for Predicting Outcomes and Monitoring Patients With Waldenström Macroglobulinemia.

Waldenström macroglobulinemia (WM) is an uncommon indolent B-cell lymphoma driven by MYD88 and CXCR4 mutations. Although serum B-cell maturation antigen (sBCMA) has been shown to be a prognostic and monitoring tool for multiple myeloma patients, it has not been evaluated among those with WM. We assessed sBCMA levels among 50 WM patients: 16 had received prior therapy, while 34 were treatment-naïve (TN), 19 of whom never went on to require therapy (smoldering [S]WM). Levels were higher among WM patients (median, 63.76 ng/mL) than healthy subjects (median, 35.24 ng/mL; p < 0.0001). TNWM patients who required therapy showed higher initial levels (median, 137.71 ng/mL) than those with SWM (median, 50.19 ng/mL; p = 0.0002). sBCMA also correlated with disease status: levels decreased at best response (≥ minimal response; median, 38.36 ng/mL) compared to baseline (median, 117.00 ng/mL; p = 0.0078) and increased among patients who developed progressive disease (median, 79.42 ng/mL; p = 0.0625). Baseline sBCMA levels positively correlated with β2 microglobulin (p = 0.0193) and M-protein (p = 0.0450), and negatively with hemoglobin (p = 0.0090) and albumin (p = 0.0016). Overall, these findings suggest sBCMA may serve as a biomarker for prognosis and monitoring for WM patients.