Circulating endothelial progenitor cells as potential prognostic biomarker in multiple myeloma

Recent studies suggest that endothelial progenitor cells (EPCs) are mobilized from bone marrow to the peripheral circulation and aid in tumor neovascularization. In this study, circulating EPC (cEPC) numbers were assessed and correlation with clinical and laboratory parameters was determined in 75 patients with multiple myeloma (MM). Higher numbers of cEPCs (defined as CD45-/dim CD34+CD133+CD31+cells) were observed in MM as compared to healthy controls (n = 10; p < 0.001), which increased progressively from stage I to stage III (p < 0.001). A significant decline in cEPC numbers after therapy was observed in patients who attained at least a partial response (n = 47; p < 0.001). cEPCs correlated with response duration, at a baseline cut-off value of 19.6 cEPCs/mu L (p = 0.006) and 6.5 cEPCs/mu L after therapy (p < 0.001). This study suggests that cEPC numbers and changes in their levels may serve as a potential biomarker of disease severity, response to therapy and treatment outcome in MM.