OBJECTIVE
To test the methodical and pre-analytical performance of a new multiplex cancer biomarker panel using magnetic beads.
METHODS
The MILLIPLEX(®) MAP Human Circulating Cancer Biomarker Magnetic Bead Panel 1 comprises the tumor markers carcinoembryonic antigen, alpha-fetoprotein, total prostate-specific antigen, cancer antigen 15-3, cancer antigen <em>19</em>-9, cancer antigen 125, cytokeratine <em>19</em>-fragment, β-human chorionic gonadotropin, human epididymis protein 4, osteopontin, prolactin, the cell death and angiogenesis markers soluble Fas, soluble Fas-ligand, tumor necrosis <em>factor</em> related apoptosis-inducing ligand, vascular endothelial <em>growth</em> <em>factor</em> and the immunological markers interleukin-6 (IL-6), IL-8, tumor necrosis <em>factor</em>-α, transforming <em>growth</em> <em>factor</em> α, <em>fibroblast</em> <em>growth</em> <em>factor</em>-2, macrophage migration inhibitory <em>factor</em>, leptin, hepatocyte <em>growth</em> <em>factor</em>, and stem cell <em>factor</em>. We determined intra- and inter-assay imprecision as well as dilution linearity using quality controls and serum pools. Furthermore, the stability of the 24 biomarkers examined in this panel was ascertained by testing the influence of different storage temperatures and time span before centrifugation.
RESULTS
For all markers measured in the synthetic internal quality controls, the intra-assay imprecision ranged between 2.26% and 9.41%, while for 20 of 24 measured markers in the physiological serum pools, it ranged between 1.68% and 12.87%. The inter-assay imprecision ranged between 1.48%-17.12% for 23 biomarkers in synthetic, and between 4.59%-23.88% for 18 biomarkers in physiological quality controls. Here, single markers with very low concentration levels had increased imprecision rates. Dilution linearity was acceptable (70%-130% recovery) for 20 biomarkers. Regarding pre-analytical influencing factors, most markers were stable if blood centrifugation was delayed or if serum was stored for up to 24 h at 4 °C and 25 °C after centrifugation. Comparable results were obtained in serum and plasma for most markers. However, great changes were observed for single markers.
CONCLUSIONS
MILLIPLEX(®) MAP Human Circulating Cancer Biomarker Magnetic Bead Panel 1 assay is a stable and precise method for detection of most biomarkers included in the kit. However, single markers have to be interpreted with care.