Immunosuppressant Monitoring-Performance of the First Mass Spectrometry-Based Automated Clinical Analyzer Cascadion.

BACKGROUND: Automatic analyzers simplify processes and may help improve standardization. The first automated analyzer based on mass spectrometry is available and offers a panel for monitoring cyclosporin A, tacrolimus, sirolimus, and everolimus. Method comparisons and evaluation tests are presented to verify the capability of the Cascadion system for use in a clinical laboratory. METHODS: Sample preparation and measurements were performed using the Cascadion clinical analyzer. More than 1000 measurement values of patient samples were compared with an in vitro diagnostic-certified assay run on a liquid chromatography tandem mass spectrometry instrument. Precision and accuracy were determined using commercial quality control and external quality assessment (EQA) samples. RESULTS: A good correlation between the 2 instruments was observed (Pearson correlation r = 0.956-0.996). Deming regression revealed 95% confidence intervals of slopes and intercepts covering the values 1 and 0, for sirolimus and everolimus, respectively, indicating equivalence of both measuring systems. However, for cyclosporin A, a bias was observed and confirmed using a Bland-Altman plot (-9.1%). Measurement repeatability and intermediate measurement precision were appropriate showing coefficients of variation of 0.9%-6.1% and 2.0%-5.3%, respectively. Accuracy according to internal quality controls was 85%-111% and 81%-100% in the EQA samples of Reference Institute of Bioanalytics and Laboratory of the Government Chemist, respectively. High robustness was found with regard to the linearity of the calibration lines (linear regression coefficient r2 > 0.99). Carryover was negligible (0.1%). CONCLUSIONS: The Cascadion automatic analyzer produced convincing results in the measurement of patient, control, and EQA samples. The throughput was sufficient for routine use. Overall, it can be used as an alternative to open liquid chromatography tandem mass spectrometry instruments for immunosuppressant monitoring, simplifying processes without the need for specially trained personnel.

Performance of the New RapidFire System for Therapeutic Monitoring of Immunosuppressants.

BACKGROUND: Typical runtimes for quantitation of immunosuppressants in whole blood based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) are in the order of a few minutes per sample. The Agilent RapidFire-MS/MS system uses solid phase extraction cartridges instead of chromatography columns and benefits from runtimes below 15 seconds. The purpose of this study was to figure out if this high-throughput instrument could be capable for application in the clinical laboratory to quantify cyclosporine A, everolimus, sirolimus, and tacrolimus. METHODS: 1172 measurement results from patient samples were compared between our routinely used LC-MS/MS system and the RapidFire 360 coupled to a tandem mass spectrometer. Sample preparation and routine measurement were performed using a certified kit. Imprecision and accuracy were investigated analyzing 3 commercial quality controls of different concentrations. RESULTS: Both measurement procedures showed excellent agreement (Pearson correlation coefficients r = 0.964-0.995). Deming regression revealed confidence intervals (95%) for slopes and intercepts of the linear equation, which covered the values 1 and 0, respectively, in almost all cases. The relative differences between both methods were marginal (1.7%-2.9%). Good intraday precision (coefficients of variation, 0.7%-9.0%) and interday precision (coefficients of variation, 2.8%-8.4%) for all immunosuppressants were achieved. The recovery of target concentrations was 81%-116%. High robustness was found with regard to linearity of the calibration lines (linear regression coefficients r ≥ 0.99). There was only negligible carry-over (cyclosporine A, 0.07%) and high endurance of the solid phase extraction cartridge (>3000 injections). CONCLUSIONS: The RapidFire-MS/MS system provided convincing results measuring patient samples and quality control materials. Together with a high throughput and a high robustness, it could represent an alternative to LC-MS/MS instruments in therapeutic drug monitoring.