B-314 Evaluation of Everolimus QMS Immunoassay on Roche Cobas c502 and Indiko Plus Analyzers

Abstract

Abstract Background Everolimus has a narrow therapeutic window and significant intra-individual variability. Rapid turn-around-time and precise results are critical for therapeutic drug monitoring and adequate dose adjustment. The Thermo Scientific Quantitiative Microsphere System (QMS®) everolimus immunoassay is the only FDA-approved immunoassay for measuring everolimus in human blood. The analytical performance of the Thermo Scientific QMS® everolimus immunoassay on Indiko Plus and Roche c502 platforms were evaluated and compared to LC-MS/MS. Methods Whole blood EDTA-anticoagulated patient samples were pretreated with methanol and precipitation reagent (immunoassay) or zinc sulfate/methanol (LC-MS/MS) to remove proteins before analysis. Imprecision was determined by running quality control and patient samples 20 times. Fifty transplant samples were used for method comparison. Deming regression, correlation coefficient (R2), and % bias plot analysis were performed using EP Evaluator® software. Results Imprecision (%CV) for QMS everolimus assay on Roche c502 was 16.7% (mean = 4.4 ng/mL) and 9.7% (mean = 10.3 ng/mL) for patient pools, and 16.5% (mean = 4.7 ng/mL), 10.3% (mean = 7.8 ng/mL), 10.7% (mean = 14.5 ng/mL) for quality control. QMS everolimus assay imprecision on Indiko Plus platform had CV of 3.1% (mean = 4.3 ng/mL), 3.3% (mean = 9.3 ng/mL), 2.8% (mean 14.3 ng/mL) for liver transplant patients and 3.3% (mean = 4.2 ng/mL), 3.3% (mean 8.3 ng/mL), 3.1 % (mean 15.6 ng/mL) for quality control. Patient comparison studies between Roche c502 vs LC-MS/MS revealed a R2 of 0.82, slope of 1.3 and %bias of −2.7%. QMS on Indiko Plus vs LC-MS/MS revealed a R2 of 0.84, slope of 0.96 and %bias of −21.9%. Conclusions The Indiko Plus platform had a constant negative bias vs LC-MS/MS while the Roche’s platform had lower average bias but it resulted in greater scatter in the therapeutic range (3–8 ng/mL) vs LC-MS/MS. Overall, we observed increased imprecision on the c502 analyzer.