Cyclosporin A Monitoring in Allogeneic Hematopoietic Stem-Cell Transplant Recipients: A Comparison Between Siemens Viva-ProE System and LC-MS/MS

Background: Allogeneic hematopoietic stem-cell transplantation is a critical treatment for blood-related diseases often complicated by graft-versus-host disease and managed using cyclosporin A (CsA). Therapeutic drug monitoring is essential due to the narrow therapeutic window of CsA. Methods: In this study, a liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the quantification of whole-blood CsA concentrations was developed and validated. CsA concentration in allogeneic hematopoietic stem-cell transplantation patients was measured using the newly established LC-MS/MS and the enzyme multiplied immunoassay technique–based Siemens viva-ProE system. The results from both methods were statistically analyzed across different concentration ranges to evaluate method agreement, correlation, and clinical implications. Results: The established LC-MS/MS method demonstrated excellent linearity (r 2 = 0.9983) within the CsA concentration range of 10–1000 ng/mL, with the validation parameters meeting the bioanalytical method validation criteria. Analysis of 161 samples revealed a strong correlation (r = 0.9908) between the methods; however, Siemens viva-ProE system overestimated CsA levels by an average of 8.7%, with a greater bias at higher concentrations. Correction through Deming regression significantly improved the agreement at therapeutically relevant thresholds. Conclusions: The developed LC-MS/MS assay demonstrated acceptable performance in measuring CsA concentration in whole blood. The comparison between the 2 methods highlights the need for method specification in therapeutic drug monitoring and provides regression equations to enhance the monitoring accuracy in clinical practice.