RESUMO
OBJECTIVES: Everolimus (EVR), a mTOR inhibitor immunosuppressant approved for renal, liver and cardiac transplants. This study established the appropriate TDM performances of the Thermo Scientific QMS EVR Assay by using the Beckman DxC, followed by comparison to the Thermo Scientific Indiko and a previously published LC-MS/MS assay, and Beckman AU680 and AU5800 analyzers. DESIGN AND METHODS: The study initially established acceptable linearity, precision and accuracy of the QMS EVR turbidimetric assay. Sample preparation was initiated by mixing patient whole blood with methanol and a precipitation reagent. Supernatant was transferred to sample cups. Drug in the supernatant and drug coated on microparticle compete for the limited number of antibody binding sites. If EVR is absent in the sample supernatant, EVR coated microparticles are agglutinated in the presence of antibody reagent. If EVR is present, agglutination is partially inhibited, depending on EVR concentration. Calibrators range was from 1.5 to 20ng/mL. Comparison studies data were analyzed by Deming Regression and Bland-Altman plots. RESULTS: Precision studies showed the following mean concentrations 4.00-4.72, 7.70-8.20 and 14.80-15.56ng/mL, and CVs of 3.1-8.7%, 3.4-8.9% and 2.6-4.4% respectively. Comparison of analyses of 107 de-identified transplant samples by three analyzers - Indiko, DxC and AU680 showed: EVR concentrations from <1.5 to 13.6ng/mL, slopes 1.000 to 1.076, intercepts -0.053 to 0.462, and R 0.945 to 0.981. Another series of comparison studies (n=104) of Indiko and AU680 with LC-MS/MS showed the following: slopes 1.035 to 1.086, intercepts -0.019 to -0.265, and R 0.924 to 0.980. 2013-2016 CAP survey results were acceptable. CONCLUSIONS: Based on the experience of the past 3.5years, Thermo Scientific QMS EVR Immunoassay using four different analyzers offered adequate limit of detection and acceptable accuracy and precision, suitable for monitoring renal and liver transplant recipients.
