Therapeutic drug monitoring

Evaluation of QMS everolimus assay using Indiko analyzer: comparison with an ultra-performance liquid chromatography-tandem mass spectrometry method.

PMID 25254414


A new particle-enhanced turbidimetric immunoassay, Quantitative Microsphere System (QMS) everolimus, was evaluated using an Indiko analyzer (Thermo Fisher Scientific). Analytical performances (imprecision, linearity, limit of detection, and limit of quantification) of this new immunoassay were evaluated. The method was compared with an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) method and with the previously available Innofluor Certican immunoassay on 120 whole-blood samples from 74 transplant recipients. Passing-Bablok regression and Bland-Altman plot were used for method comparisons. Within- and between-day coefficients of variation were <10% at mean levels of 4.3, 8.2, and 15.9 ng/mL, respectively. This assay could be used at everolimus concentrations between 1.7 and 20 ng/mL. We obtained a Passing-Bablok regression of y = 0.99 × -0.15 (r = 0.95) when comparing with the UPLC/MS/MS method and of y = 0.81 × -0.09 (r = 0.94) when comparing with Innofluor assay. The mean and limits of agreement (mean ± 1.96 SD) of the difference between QMS everolimus and UPLC/MS/MS were -0.13 (from -2.0 to 1.74) ng/mL and were -1.19 (from -3.39 to 1.01) ng/mL between QMS everolimus and Innofluor. The QMS everolimus method on Indiko analyzer demonstrated reliable and reproducible performances allowing routine monitoring in transplant patients.