Accuracy evaluation of automated electrochemiluminescence immunoassay for everolimus and sirolimus compared to liquid chromatography-tandem mass spectrometry

Background We evaluated the analytical performance of a newly developed electrochemiluminescence immunoassay for everolimus and sirolimus compared to that of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods According to Clinical and Laboratory Standards Institute guidelines, the analytical performance including precision, recovery, linearity, and carryover was evaluated. For correlation evaluation, the results of Elecsys (R) analysis of everolimus and sirolimus were compared with those of LC-MS/MS using 120 samples from patients treated with everolimus or sirolimus. Results The within-run and total imprecision values were as follows: 2.3%-4.5% and 4.5%-6.4% for the everolimus assay; 3.3%-4.8% and 4.7%-8.1% for the sirolimus assay, respectively. The measured concentration was linear over the range of 0.718-27.585 ng/mL for everolimus analysis and 0.789-26.880 ng/mL for sirolimus analysis (all R-2 > 0.99). Recovery was 93.5%-105.5% for the everolimus assay and 99.2%-109.1% for the sirolimus assay (except lowest levels). Carryover was -1.09% for the everolimus assay and -0.12% for the sirolimus assay. The results of the two chemiluminescence immunoassays showed acceptable correlations with those of LC-MS/MS (R = 0.9585 and R = 0.9799, respectively). The two immunoassays showed slightly proportional biases compared to LC-MS/MS. Conclusion Elecsys (R) Everolimus and Sirolimus assays showed acceptable analytical performance in precision, linearity, and correlation compared to LC-MS/MS These methods can be adopted in the clinical laboratory for rapid therapeutic drug monitoring of patients who require treatment with immunosuppressants.