Therapeutic drug monitoring (TDM) of immunosuppressive drugs is crucial in organ-transplanted patients to prevent rejection or toxic effects due to inadequate dosage. Mycophenolic acid (MPA) is a commonly used immunosuppressant in this setting. Nowadays, MPA concentrations are monitored by Enzyme Multiplied Immunoassay Technology (EMIT), and Liquid Chromatography (LC)-based techniques, particularly coupled to Tandem Mass Spectrometry (LC–MS/MS). This study evaluates the concordance between TDM results for MPA obtained through CE-IVD EMIT and LC–MS/MS assays in plasma samples. LC–MS/MS quantification was based on a commercial kit and the analytical performance in terms of accuracy was tested through external proficiency tests and inter-laboratory comparison with a home-made HPLC-UV method. Both these evaluations confirmed the reliability of the LC–MS/MS method (1.6 % and 9.0 % of bias, respectively). Conversely, the comparison between EMIT and LC–MS/MS showed overestimation by EMIT of 33.5 %. This bias resulted concentration-dependent, ranging from 46.4 % in the concentration range of 1–2 mg/L, to 21.4 % over 4 mg/L. Considering the theoretical clinical impact of this overestimation, a fraction comprised between 12.4 % and 31.4 % of samples which resulted over three different minimum effective concentration values by EMIT (no indication for dose adjustment) had discordant indications by LC–MS/MS (dose adjustment needed). Concluding, this study highlights a clinically relevant systematic overestimation of MPA concentration by EMIT, supporting the switch to LC–MS/MS techniques for TDM purpose. However, further prospective studies are needed in order to evaluate the clinical impact of switching the TDM activity from EMIT to LC–MS/MS in a larger cohort in a long period.

Lack of concordance between EMIT assay and LC-MS/MS for Therapeutic Drug Monitoring of Mycophenolic Acid: Potential increased risk for graft rejection?

De Nicolo A.
First
;
Ianniello A.;Antonucci M.;D'Avolio A.
Co-last
;
2020

Abstract

Therapeutic drug monitoring (TDM) of immunosuppressive drugs is crucial in organ-transplanted patients to prevent rejection or toxic effects due to inadequate dosage. Mycophenolic acid (MPA) is a commonly used immunosuppressant in this setting. Nowadays, MPA concentrations are monitored by Enzyme Multiplied Immunoassay Technology (EMIT), and Liquid Chromatography (LC)-based techniques, particularly coupled to Tandem Mass Spectrometry (LC–MS/MS). This study evaluates the concordance between TDM results for MPA obtained through CE-IVD EMIT and LC–MS/MS assays in plasma samples. LC–MS/MS quantification was based on a commercial kit and the analytical performance in terms of accuracy was tested through external proficiency tests and inter-laboratory comparison with a home-made HPLC-UV method. Both these evaluations confirmed the reliability of the LC–MS/MS method (1.6 % and 9.0 % of bias, respectively). Conversely, the comparison between EMIT and LC–MS/MS showed overestimation by EMIT of 33.5 %. This bias resulted concentration-dependent, ranging from 46.4 % in the concentration range of 1–2 mg/L, to 21.4 % over 4 mg/L. Considering the theoretical clinical impact of this overestimation, a fraction comprised between 12.4 % and 31.4 % of samples which resulted over three different minimum effective concentration values by EMIT (no indication for dose adjustment) had discordant indications by LC–MS/MS (dose adjustment needed). Concluding, this study highlights a clinically relevant systematic overestimation of MPA concentration by EMIT, supporting the switch to LC–MS/MS techniques for TDM purpose. However, further prospective studies are needed in order to evaluate the clinical impact of switching the TDM activity from EMIT to LC–MS/MS in a larger cohort in a long period.
187
113337
1
5
EMIT; Immunosuppressant; MPA; Mycophenolate; Rejection; TDM
De Nicolo A.; Ianniello A.; Benagli C.; Della Bruna R.; Keller F.; Antonucci M.; D'Avolio A.; Cantu M.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/1759600
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