title: Evaluation of QMS everolimus assay using Indiko analyzer: comparison with an ultra-performance liquid chromatography-tandem mass spectrometry method.
abstract: BACKGROUND
  A new particle-enhanced turbidimetric immunoassay, Quantitative Microsphere System (QMS) everolimus, was evaluated using an Indiko analyzer (Thermo Fisher Scientific).
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  The QMS everolimus method on Indiko analyzer demonstrated reliable and reproducible performances allowing routine monitoring in transplant patients.
authors.affiliation: *Laboratoire de Biochimie; †Service d'Hépato-gastroentérologie et transplantation; and ‡Service de Néphrologie, Dialyse Péritonéale et Transplantation, CHRU Montpellier, Université Montpellier 1, Montpellier, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Buthiau
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Bargnoux
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Badiou
authors.forename: Thibault
authors.initials: T
authors.lastname: Sutra
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Dupuy
authors.forename: Georges-Philippe
authors.initials: GP
authors.lastname: Pageaux
authors.forename: Georges
authors.initials: G
authors.lastname: Mourad
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Cristol
mesh_terms: D000368:Aged; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D016903:Drug Monitoring / Q000379:methods; D000068338:Everolimus / Q000008:administration & dosage / Q000097:blood*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000097:blood*; D057230:Limit of Detection; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D016377:Organ Transplantation; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D007166:Immunosuppressive Agents; D000068338:Everolimus