Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry for Cyclosporine Analysis in Human Whole Blood and Comparison With an Antibody-Conjugated Magnetic Immunoassay

LC-MS/MS and EMIT measure the whole blood concentration of cyclosporine A: The two methods yield concordant results within the dynamic range of the latter, but the former shows broader application scenarios

Cyclosporine A (CsA) is a widely used immunosuppressive drug with a narrow therapeutic index and large individual differences. Its therapeutic and toxic effects are closely related to blood drug concentrations, requiring routine therapeutic drug monitoring (TDM). The current main methods for TDM of CsA are enzyme multiplied immunoassay technique (EMIT) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, few study on the method comparison of the EMIT and LC-MS/MS for the measurement of whole blood CsA concentration in children has been reported. In this study, we developed a simple and sensitive LC-MS/MS assay for the determination of CsA, and 657 cases of CsA concentrations were determined from 197 pediatric patients by a routine EMIT assay and by the validated in-house LC-MS/MS method on the same batch of samples, aimed to address the aforementioned concern. Consistency between the two assays was evaluated using linear regression and Bland-Altman analysis. The linear range of LC-MS/MS was 0.500-2000 ng/mL and that of the EMIT was 40-500 ng/mL, respectively. Overall, the correlation between the two methods was significant (r-value ranging from 0.8842 to 0.9441). Unsatisfactory consistency was observed in the concentrations < 40 ng/mL (r = 0.7325) and 200-500 ng/mL (r = 0.6851). Bland-Altman plot showed a mean bias of -18.0 % (±1.96 SD, -73.8 to 37.8 %) between EMIT and LC-MS/MS. For Passing-Bablok regression between EMIT and LC-MS/MS did not differ significantly (p > 0.05). In conclusion, the two methods were closely correlated, but the CsA concentration by LC-MS/MS assay was slightly higher than that by EMIT method. Switching from the EMIT assay to the LC-MS/MS method was acceptable, and the LC-MS/MS method will receive broader application in clinical settings due to its better analytical capabilities, but the results need to be further verified in different laboratories.

A simple and accurate LC‑MS/MS method for monitoring cyclosporin A that is suitable for high throughput analysis

With time, the number of samples in clinical laboratories from therapeutic drug monitoring has increased. Existing analytical methods for blood cyclosporin A (CSA) monitoring, such as high-performance liquid chromatography (HPLC) and immunoassays, have limitations including cross-reactivity, time consumption, and the complicated procedures involved. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has long been considered the reference standard owing to its high accuracy, specificity, and sensitivity. However, large numbers of blood samples, multi-step preparation procedures, and longer analytical times (2.5-20 min) are required as a consequence of the different technical strategies, to ensure good analytical performance and routine quality assurance. A stable, reliable, and high throughput detection method will save personnel time and reduce laboratory costs. Therefore, a high throughput and simple LC-MS/MS method was developed and validated for the detection of whole-blood CSA with CSA-d12 as the internal standard in the present study. Whole blood samples were prepared through a modified one-step protein precipitation method. A C18 column (50x2.1 mm, 2.7 µm) with a mobile phase flow rate of 0.5 ml/min was used for chromatographic separation with a total running time of 4.3 min to avoid the matrix effect. To protect the mass spectrometer, only part of the sample after LC separation was allowed to enter the mass spectrum, using two HPLC systems coupled to one mass spectrometry. In this way, throughput was improved with detection of two samples possible within 4.3 min using a shorter analytical time for each sample of 2.15 min. This modified LC-MS/MS method showed excellent analytical performance and demonstrated less matrix effect and a wide linear range. The design of multi-LC systems coupled with one mass spectrometry may play a notable role in the improvement of daily detection throughput, speeding up LC-MS/MS, and allowing it to be an integral part of continuous diagnostics in the near future.

Sensitive, wide-range and high-throughput quantification of cyclosporine in whole blood using ultra-performance liquid chromatography coupled to tandem mass spectrometry and comparison with an antibody-conjugated magnetic immunoassay

Because either trough or peak concentration at 2 h after administration is measured in routine therapeutic drug monitoring for cyclosporine A (CyA), a quantification method with a wide-range calibration curve capable of simultaneously measuring both concentrations is required. We developed a sensitive, wide-range and high-throughput quantification method for CyA in whole blood using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and compared patients' blood CyA levels measured by UPLC-MS/MS and antibody-conjugated magnetic immunoassay (ACMIA). Whole blood samples were prepared by solid-phase extraction using Oasis HLB μElution plate. The UPLC-MS/MS assay showed excellent linearity over a wide calibration range of 5-2500 ng/mL. Within-batch accuracy and precision as well as batch-to-batch accuracy and precision fulfilled the criteria of US Food and Drug Administration guidelines. The blood CyA concentrations measured by the UPLC-MS/MS assay correlated strongly with those measured by ACMIA. A Bland-Altman plot showed a fixed error between CyA concentrations measured by the two methods, and the concentrations measured by the UPLC-MS/MS method were consistently lower than those measured by ACMIA. We have succeeded to develop a sensitive, wide-range and high-throughput quantification method for CyA in whole blood using UPLC-MS/MS.

Validation of a novel UPLC-HRMS method for human whole-blood cyclosporine and comparison with a CMIA immunoassay

Therapeutic drug monitoring is an essential tool when managing the therapeutic use of immunosuppressant cyclosporine A (CsA) in cases with solid organ transplantation. In China, the concentration of CsA is primarily measured using immunoassays. However, existing literature recommends mass spectrometry as the current gold standard for the quantitation of CsA. In the present study, it was attempted to develop a novel application to determine CsA concentrations by using ultra-performance liquid chromatography coupled to high-resolution mass spectrometry (UPLC-HRMS). This technique was then compared with a commercially available chemiluminescent microparticle immunoassay (CMIA) and it was investigated how clinical factors may contribute to quantitation differences between the two methods. An UPLC-Orbitrap-MS method was developed to determine CsA concentrations and this method was validated using guidelines put forward by the Food and Drug Administration from the US. In total, 127 blood samples were acquired from patients undergoing kidney transplantation and analyzed by UPLC-HRMS and CMIA assays. The novel method provided sensitive, accurate and precise results. The mean CsA concentration measured by CMIA was significantly higher than that measured by UPLC-HRMS (85.70±48.99 vs. 67.06±34.56 ng/ml, P<0.0001). Passing Bablok analysis yielded a slope of 1.34 (95% CI: 1.22-1.47) and an intercept of -2.54 (95% CI: -10.29-5.52). A group of samples with a higher metabolic ratio (hydroxylated CsA/CsA>1) exhibited larger discrepancies, while a group of samples taken from patients with a longer post-transplantation time (>10 years) featured narrow 95% CIs from -15.32 to 65.69%, as determined by Bland-Altman analysis. In summary, a reliable, accurate and rapid UPLC-HRMS method for CsA analysis was successfully developed. The measurement of CsA by the CMIA assay in renal transplant patients should be further evaluated with a specific focus on positive bias.

Comparison of sample preparation methods, validation of an UPLC-MS/MS procedure for the quantification of cyclosporine A in whole blood sample

Current main methods for therapeutic drug monitoring (TDM) of cyclosporine A (CsA) are immunoassays and liquid chromatography tandem mass spectrometry. The sample pretreatment of these methods is mainly based on extraction of drug which is bound to erythrocytes by divalent heavy metal ions (such as zinc and copper). Although these methods are effective for whole blood drug extraction and measurement, the pollution of heavy metals in sample pretreatment process will have potential negative impact on environment and human health. To overcome the pollution problem, in this study we have developed and validated an UPLC-MS/MS method for CsA determination in whole blood samples using physical pretreatment method. According to the characteristics of erythrocytes, a series of physical pretreatment methods, including sonication, freeze-thaw and osmotic burst, have been developed and evaluated. The results showed that the osmotic burst method was an effective way for drug extraction from erythrocytes. The lower limit of quantitation for CsA was 25 ng/mL, the within-run and between-run coefficient of variations were both less than 11.6 %. The agreement of the UPLC-MS/MS methods using these two sample pretreatment was evaluated by Bland-Altman plot and the two-tailed Student's T-test. Comparison studies show that the effect of erythrocyte fragmentation by osmotic burst is similar to that of zinc sulfate method. The CsA measurement of 103 whole blood samples obtained by these two UPLC-MS/MS assays were no significant difference. These results demonstrate that the sample pretreatment by osmotic burst method is an eco-friendly and precise method for detecting the whole blood CsA concentration and therapeutic drug monitoring of CsA.

Simultaneous determination of cyclosporine and tacrolimus in human whole blood by ultra-high performance liquid chromatography tandem mass spectrometry and comparison with a chemiluminescence microparticle immunoassay

Overestimation of immunoassays for cyclosporine (CsA) and tacrolimus (TAC) analysis in human whole blood is a problem. The liquid chromatography tandem mass spectrometry is recommended as a golden method for CsA and TAC analysis. The aim of the study is to develop and validate an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous determination of CsA and TAC in human whole blood and evaluate its agreement with a chemiluminescence microparticle immunoassay (CMIA). The UHPLC-MS/MS method for simultaneous determination of CsA and TAC in human whole blood was developed and validated according to the guidelines. A total of 177 CsA and 220 TAC samples were determined by UHPLC-MS/MS and CMIA, and the agreement of the two methods was evaluated by Bland-Altman plot. The calibration range of UHPLC-MS/MS method was 5 to 2000 ng/mL for CsA and 0.2 to 80 ng/mL for TAC. The inaccuracy and imprecision were -13.33% to 11.80% and <11.74% for CsA and -8.94% to 6.53% and <10.84% for TAC, respectively. Evaluated by Bland-Altman plot, the mean overestimation of CMIA compared to UHPLC-MS/MS was 53.7% for CsA and 48.1% for TAC.