Everolimus is a novel proliferation signal inhibitor used in immunosuppressive therapies for the prevention of acute and chronic rejection. It is an immunosuppressant requiring routine monitoring in whole blood. We evaluated analytical performance of the Nanopia TDM Everolimus assay kit for the measurement of everolimus in whole blood.
Whole blood samples from patients receiving immunosuppressive therapy with everolimus after heart transplantation were used, and everolimus concentrations were measured by liquid chromatography combined with mass spectrometric detection and fluorescence polarization immunoassay and Nanopia TDM Everolimus assay.
The within-assay coefficient of variation was 4.0%–6.8% (n = 20) at everolimus concentrations of 4.4–15.7 ng/mL, whereas the day-to-day coefficient of variation ranged from 3.6% to 5.4% at everolimus concentrations of 4.8–15.9 ng/mL. The limit of quantitation was 1.5 ng/mL. Calibration curves were stable for at least 14 days. The presence of conjugated bilirubin, unconjugated bilirubin, lipemic material, rheumatoid factor, and variation of the hematocrit did not affect this assay system. There was a strong positive correlation between values obtained with the Nanopia TDM Everolimus assay kit and the results of liquid chromatography combined with mass spectrometric detection (y = 0.960x + 0.312 ng/mL; r = 0.946; n = 91), as well as with data from the fluorescence polarization immunoassay (y = 0.966x − 0.440 ng/mL; r = 0.942; n = 91).
The Nanopia TDM Everolimus assay showed good analytical performance. These results indicate that the Nanopia TDM Everolimus assay may be suitable for routine clinical use.