Enumeration and characterization of circulating multiple myeloma cells in patients with plasma cell disorders

Summary We have developed an automated assay to enumerate and characterize circulating multiple myeloma cells (CMMC) from peripheral blood of patients with plasma cell disorders. CMMC show expression of genes characteristic of myeloma and fluorescence in situ hybridisation results on CMMC correlated well with bone marrow results. We enumerated CMMC from over 1000 patient samples including separate cohorts of newly diagnosed multiple myeloma and high/intermediate risk smouldering multiple myeloma (SMM) with clinical follow‐up data. In newly diagnosed myeloma patient samples, CMMC counts correlated with other clinical measures of disease burden, including the percentage of bone marrow plasma cells, serum M protein, and International Staging System stage. CMMC counts decreased significantly from baseline when a remission was achieved due to treatment (P