biomarker; bone-marrow angiogenesis; endocan; expression; Multiple myeloma; survival

Background/Aim: Monoclonal gammopathy of unknown significance (MGUS) and smoldering multiple myeloma often precede multiple myeloma (MM). The identification of biomarkers predicting progression to MM might facilitate an earlier diagnosis of MM. Our study assessed the diagnostic value of plasma levels of endocan, a 50-kDa soluble dermatan sulfate proteoglycan produced and secreted by endothelial cells, hitherto unknown in MM, in patients with plasma cell dyscrasia. Materials and Methods: Endocan levels were determined in 96 peripheral blood plasma samples by sandwich enzyme-linked immunosorbent assay (ELISA) in healthy controls (n=12), in patients with MGUS (n=17), and in patients newly diagnosed with (n=42) or relapsed/refractory (n=25) MM. Results: Median endocan concentration increased from MGUS (315.00 pg/ml) and healthy controls (316.19 pg/ml) to newly-diagnosed MM (371.82 pg/ml; p=0.027). The low endocan levels (median=246 .20 pg/ml) in patients with relapsed/refractory MM were similar to those in healthy controls and patients with MG US. A cut-off value of >220 pg/ml endocan in peripheral blood discriminated patients newly diagnosed with MM from those with MGUS (area under the curve(AUC)=0.66, 95% confidence interval(CI)=0.55-0.81). Conclusion: The plasma levels of endocan can non-invasively differentiate patients newly diagnosed with MM from those with MGUS and should therefore be evaluated prospectively as a potential diagnostic marker.