Immunosuppressive drugs in whole blood: validation of a commercially available liquid chromatography/tandem mass spectrometry kit and comparison with immunochemical assays

The development of a bioanalytical method for the simultaneous analysis of gentamicin and tacrolimus in Rat whole blood using UHPLC-MS/MS

Tacrolimus (TAC) is commonly administered to patients who have undergone organ transplantation to prevent the immune system from rejecting the transplanted organ. Multidrug-resistant bacterial infections are the most frequent complications during the first-month post-transplantation. Old antimicrobial agents such as gentamicin (GEN) are widely used to treat opportunistic nosocomial infections in immunosuppressed TAC patients. Nephrotoxicity is a significant side effect of GEN and TAC, but some studies indicated their concurrent administration. However, there is no information on whether the combination of the two drugs may result in a more significant impairment of kidney function than either drug used separately. To investigate this, both drugs should be monitored in blood. Sample preparation was carried out using protein precipitation, requiring only 50 µL of WB sample with an extraction recovery of not less than 95.2% (GEN) and 93.2% (TAC). Analytes and internal standard (IS) were monitored using mass spectrometry (MS) in positive ion mode by multiple reaction monitoring (MRM). Chromatographic analysis was performed on an Acquity UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm), kept at 50 °C and using gradient elution. Mobile phase A contained 2 mmol/L ammonium formate acidified with 0.1% formic acid in water, and mobile phase B was a mixture of 2 mmol/L ammonium formate and 0.1% formic acid in methanol, pumped at a flow rate of 0.25 mL/min. The analysis time was only 6 min. The method was verified according to the European Medicines Agency (EMA) guidelines over a concentration range of 19.5-2500 ng/mL for GEN and 1.95-250 ng/mL for TAC. Determination coefficients for the calibration curves were found to be ≥ 0.999. Within- and between-run precision and accuracy were evaluated for both drugs with relative standard deviations (RSD) ≤ 6.5% and inaccuracy ≤ 6.6%. The proposed method was successfully applied to analyze the WB samples at different time points after the co-administration of GEN and TAC to Wistar rats. In this work, a new bioanalytical UHPLC-MS/MS method was developed and validated for simultaneous quantification of total GEN congeners (C1, C1a, and C2/C2a) and TAC in Wistar rats whole blood (WB). The protein precipitation method has been chosen to extract the drug from the WB sample. The assay method has been successfully used to estimate the concentration of TAC and GEN after co-administration in rats.

A Narrative Review of Chromatographic Bioanalytical Methods for Quantifying Everolimus in Therapeutic Drug Monitoring Applications

BACKGROUND

Methods for measuring drug levels in the body are crucial for improving therapeutic drug monitoring (TDM) and personalized medicine. In solid-organ transplants, TDM is essential for the management of immunosuppressive drugs to avoid toxicity and organ rejection. Everolimus is a commonly used immunosuppressant with a small range of safe doses; therefore, it is important to adjust the dose according to each patient's needs. Therefore, reliable methods are required to accurately measure everolimus levels. This study aims to conduct a comprehensive and updated narrative review of chromatographic bioanalytical methods for everolimus quantification.

METHODS

The authors searched for original research articles published between 2013 and 2023 in Scopus and PubMed and found 295 articles after removing duplicates. Based on their titles and summaries, 30 articles were selected for a detailed review and 25 articles were included in the final analysis.

RESULTS

Among the 25 studies, 16 used protein precipitation, mainly with methanol, to prepare the samples, 12 used high-performance liquid chromatography, 11 used ultra-performance liquid chromatography, and 2 used both. Almost all the studies (24 of 25) used tandem mass spectrometry for detection, whereas only 1 used ultraviolet.

CONCLUSIONS

This comprehensive review of bioanalytical methods for measuring everolimus using chromatography is a useful resource for researchers developing bioanalytical methods for TDM applications. Future trends in everolimus measurement include achieving lower detection limits, owing to the trend of reducing drug doses in therapy by improving sample extraction techniques and using more sensitive methods.

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.

Validation of an automated sample preparation module directly connected to LC-MS/MS (CLAM-LC-MS/MS system) and comparison with conventional immunoassays for quantitation of tacrolimus and cyclosporin A in a clinical setting

BACKGROUND

Therapeutic drug monitoring (TDM) systems generally use either liquid chromatography/tandem mass spectrometry (LC-MS/MS) or immunoassay, though both methodologies have disadvantages. In this study, we aimed to evaluate whether a CLAM-LC-MS/MS system, which consists of a sample preparation module directly connected to LC-MS/MS, could be used for clinical TDM work for immunosuppressive drugs in whole blood, which requires a hemolytic process. For this purpose, we prospectively validated this system for clinical measurement of tacrolimus and cyclosporin A in patients' whole blood. The results were also compared with those of commercial immunoassays.

METHODS

Whole blood from patients treated with tacrolimus or cyclosporin A at the Department of Nephrology and Departments of Rheumatology, Kanazawa University Hospital, from May 2018 to July 2019 was collected with informed consent, and drug concentrations were measured by CLAM-LC-MS/MS and by chemiluminescence immunoassay (CLIA) for tacrolimus and affinity column-mediated immunoassay (ACMIA) for cyclosporin A. Correlations between the CLAM-LC-MS/MS and immunoassay results were analyzed.

RESULTS

Two hundred and twenty-four blood samples from 80 patients were used for tacrolimus measurement, and 76 samples from 21 patients were used for cyclosporin A. Intra- and inter-assay precision values of quality controls were less than 7%. There were significant correlations between CLAM-LC-MS/MS and the immunoassays for tacrolimus and cyclosporin A (Spearman rank correlation coefficients: 0.861, 0.941, P < 0.00001 in each case). The drug concentrations measured by CLAM-LC-MS/MS were about 20% lower than those obtained using the immunoassays. CLAM-LC-MS/MS maintenance requirements did not interfere with clinical operations. Compared to manual pretreatment, automated pretreatment by CLAM showed lower inter-assay precision values and greatly reduced the pretreatment time.

CONCLUSIONS

The results obtained by CLAM-LC-MS/MS were highly correlated with those of commercial immunoassay methods. CLAM-LC-MS/MS offers advantages in clinical TDM practice, including simple, automatic pretreatment, low maintenance requirement, and avoidance of interference.

Ultra-high throughput dual channel liquid chromatography with tandem mass spectrometry for quantification of four immunosuppressants in whole blood for therapeutic drug monitoring

Liquid chromatography with tandem mass spectrometry (LC-MS/MS) is the golden standard for immunosuppressants analyses, where optimising throughput by parallel chromatography can reduce costs and turnaround time. We aimed to double our system throughput using a dual LC-MS/MS setup. Therefore, two independent UPLC systems were hyphenated to one triple quadrupole MS, with staggered injections from one autosampler on alternating columns. The method simultaneously measured the analytes tacrolimus, sirolimus, everolimus, and cyclosporin A in whole blood using isotope dilution, with a run time of 1.5 min. Using the dual LC-MS/MS system, net run-to-run time improved from 2.3 to 0.98 min per injection, where throughput increased from 26 to 61 injections per hour. For Performance Qualification, 1101 clinical samples were measured on the dual LC-MS/MS system in addition to the standard system, during a period of one month, and the results were compared using Passing Bablok regression and Bland Altman analysis. There was excellent agreement for all four analytes, with regression slopes of 0.98-1.02x and intercepts of -0.11-0.88 µg/L. Minor bias was demonstrated between the systems with mean differences from -0.93 to 1.43%. In conclusion, the throughput was doubled and idle MS time was reduced with good agreement to the standard system. Currently, the method is applied for clinical routine with frequent peak intensities of >180 injections per day.

Evaluation of the interchangeability between the new fully-automated affinity chrome-mediated immunoassay (ACMIA) and the Quantitative Microsphere System (QMS) with a CE-IVD-certified LC-MS/MS assay for therapeutic drug monitoring of everolimus after solid organ transplantation

OBJECTIVES

This study aims to evaluate the interchangeability between the Siemens Healthineers' "EVRO" new affinity chrome-mediated immunoassay (ACMIA/EVRO) and Thermo Fisher Scientific's "EVER" Quantitative Microsphere System (QMS/EVER) with Chromsystems' CE-IVD-certified "MassTox" liquid-chromatography/tandem-mass spectrometry (LC-MS/MS) assay for the therapeutic drug monitoring of everolimus.

METHODS

A single lot of reagent, calibrators and controls were used for each assay. A total of 67 whole blood samples (n=67) from patients receiving solid organ transplant were analyzed (n=31 with kidney transplant and n=36 with liver transplant); Passing-Bablok regression and Bland-Altman difference plot were used to evaluate bias and individual agreement; LC-MS/MS analysis was used to measure the actual concentrations of calibrators and controls compared to the assigned value.

RESULTS

ACMIA/EVRO did not show any systematic bias compared to LC-MS/MS (intercept=0.244 ng/mL, 95% CI: -0.254 to 0.651 ng/mL). Nevertheless, significant proportional bias (slope=1.511, 95% CI: 1.420 to 1.619) associated to a combined bias of 44.8% (95% CI: 41.2-48.3%) was observed. Conversely, QMS/EVER did not show any bias at both systematic (intercept=-0.151 ng/mL, 95% CI: -0.671 to 0.256 ng/mL) and proportional level (slope=0.971, 95% CI: 0.895 to 1.074) with a non-statistically significant combined bias of -3.6% (95% CI: -8.4-1.1%). Based on a concentration of calibrators and controls above the assigned value for both the analytical methods, in the ACMIA/EVRO a correction which was approximately one-third of the correction for the QMS/EVER was observed.

CONCLUSIONS

ACMIA/EVRO but not QMS/EVER shows a lack of interchangeability with the CE-IVD-certified LC-MS/MS assay. We hypothesize that, as the ACMIA/EVRO uses an anti-sirolimus antibody, the under-corrected assigned value in the assay calibrators was not sufficient to reproduce the everolimus metabolites cross-reactivity occurring in real samples.

Ambient Ionization Mass Spectrometry: Application and Prospective

Mass spectrometry (MS) is a formidable analytical tool for the analysis of non-polar to polar compounds individually and/or from mixtures, providing information on the molecular weights and chemical structures of the analytes. During the last more than one-decade, ambient ionization mass spectrometry (AIMS) has developed quickly, producing a wide range of platforms and proving scientific improvements in a variety of domains, from biological imaging to quick quality control. These methods have made it possible to detect target analytes in real time without sample preparation in an open environment, and they can be connected to any MS system with an atmospheric pressure interface. They also have the ability to analyze explosives, illicit drugs, disease diagnostics, drugs in biological samples, adulterants in food and agricultural products, reaction progress, and environmental monitoring. The development of novel ambient ionization techniques, such as probe electrospray ionization, paper spray ionization, and fiber spray ionization, employed even at picolitre to femtolitre solution levels to provide femtogram to attogram levels of the target analytes. The special characteristic of this ambient ion source, which has been extensively used, is the noninvasive property of PESI of examination of biological real samples. The results in the current review supports the idea that AIMS has emerged as a pioneer in MS-based approaches and that methods will continue to be developed along with improvements to existing ones in the near future.

Review of the Use of Liquid Chromatography-Tandem Mass Spectrometry in Clinical Laboratories: Part I-Development

The process of method development for a diagnostic assay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) involves several disparate technologies and specialties. Additionally, method development details are typically not disclosed in journal publications. Method developers may need to search widely for pertinent information on their assay(s). This review summarizes the current practices and procedures in method development. Additionally, it probes aspects of method development that are generally not discussed, such as how exactly to calibrate an assay or where to place quality controls, using examples from the literature. This review intends to provide a comprehensive resource and induce critical thinking around the experiments for and execution of developing a clinically meaningful LC-MS/MS assay.

Differential Effect of a Continental Breakfast on Tacrolimus Formulations With Different Release Characteristics

Food reduces tacrolimus bioavailability after immediate-release tacrolimus (IR-Tac) and after a new prolonged-release tacrolimus formulation (PR-Tac), when using a high-fat breakfast, but the effects of a continental breakfast on PR-Tac are unknown. In an open-label, 4-phase, randomized, 2-sequence, crossover pharmacokinetic trial, 36 healthy volunteers (18 females) received single 5-mg tacrolimus doses as PR-Tac and as IR-Tac fasted or with a standardized continental breakfast. Tacrolimus pharmacokinetics were analyzed using noncompartmental methods and mixed-model analysis of variance. The continental breakfast significantly decreased average tacrolimus exposure (area under the plasma concentration-time curve) with both preparations (IR-Tac, 67%; 90% confidence interval [CI], 59%-75%; P < .01; and PR-Tac, 79%; 90%CI, 70%-89%; P < .01) with a nonsignificant difference between both preparations (P = .10). The maximum concentration (C_max ) and the time to maximum concentration (t_max ) were significantly affected only after IR-Tac (C_max IR-Tac, 39%; 90%CI, 34%-45%; P < .01; and PR-Tac, 87%; 90%CI, 76%-101%; P = .11; t_max IR-Tac, 212%, 90%CI, 179%-252%; P < .01; and PR-Tac, 101%; 90%CI, 86%-120%; P = .89), which was significantly different between both preparations (P < .01). Considering switching from IR-Tac to PR-Tac, predicted dose requirements differed according to the timing of drug intake in relation to food. In conclusion, a continental breakfast decreased average tacrolimus exposure of both preparations to a similar extent. C_max and t_max were affected only after IR-Tac. The effect of a standardized continental breakfast on PR-Tac was considerably smaller than previously reported effects of a high-fat breakfast on PR-Tac.

Rapid determination of tacrolimus and sirolimus in whole human blood by direct coupling of solid-phase microextraction to mass spectrometry via microfluidic open interface

Immunosuppressive drugs are administered to decrease immune system activity (e.g. of patients undergoing solid organ transplant). Concentrations of immunosuppressive drugs (ISDs) in circulating blood must be closely monitored during the period of immunosuppression therapy due to adverse effects that take place when concentration levels fall outside of the very narrow therapeutic concentration range of these drugs. This study presents the rapid determination of four relevant immunosuppressive drugs (tacrolimus, sirolimus, everolimus, and cyclosporine A) in whole human blood by directly coupling solid-phase microextraction to mass spectrometry via the microfluidic open interface (Bio-SPME-MOI-MS/MS). The BioSPME-MOI-MS/MS method offers ≤ 10% imprecision of in-house prepared quality controls over a 10-day period, ≤ 10% imprecision of ClinCal® Recipe calibrators over a three-day period, and single total turnaround time of ∼ 60 min (4.5 min for high throughput). The limits of quantification were determined to be 0.8 ng mL^-1 for tacrolimus, 0.7 ng mL^-1 sirolimus, 1.0 ng mL^-1 for everolimus, and 0.8 ng mL^-1 for cyclosporine. The limits of detection were determined to be 0.3 ng mL^-1 for tacrolimus, 0.2 ng mL^-1 for sirolimus, 0.3 ng mL^-1 for everolimus, and 0.3 ng mL^-1 for cyclosporine A. The R² values for all analytes were above 0.9992 with linear dynamic range from 1.0 mL^-1 to 50.0 ng mL^-1 for tacrolimus, sirolimus, and everolimus while from 2.5 ng mL^-1 to 500.0 ng mL^-1 for cyclosporine A. To further evaluate the performance of the present method, 95 residual whole blood samples of tacrolimus and sirolimus from patients undergoing immunosuppression therapy were used to compare the Bio-SPME-MOI-MS/MS method against a clinically validated reference method based on chemiluminescent microparticle immunoassay, showing acceptable results. Our results demonstrated that Bio-SPME-MOI-MS/MS can be considered as a suitable alternative to existing methods for the determination of immunosuppressive drugs in whole blood providing faster analysis, better selectivity and sensitivity, and a wider dynamic range than current existing approaches.

Tacrolimus trough monitoring guided by mass spectrometry without accounting for assay differences is associated with acute kidney injury in lung transplant recipients

PURPOSE

Tacrolimus is a nephrotoxic immunosuppressant historically monitored via enzyme-based immunoassay (IA). After 2011, the 2 largest laboratory companies in the United States implemented tacrolimus quantification by liquid chromatography-mass spectrometry (LC-MS); this method excludes metabolites, potentially resulting in lower quantified drug concentrations. We sought to determine if tacrolimus therapeutic drug monitoring via LC-MS, as performed using trough targets originally derived from IA values, influences clinical outcomes.

METHODS

In a single-center retrospective cohort study of lung transplant recipients, risks of acute kidney injury, acute renal failure, and new-onset diabetes after transplantation, as well as chronic lung allograft dysfunction-free survival, were compared in 82 subjects monitored by LC-MS and 102 subjects monitored by IA using Cox proportional hazard models adjusted for age, sex, baseline renal function, and race.

RESULTS

LC-MS-based monitoring was associated with a greater risk of acute kidney injury (adjusted hazard ratio, 1.65; 95% confidence interval, 1.02-2.67). No statistically significant differences in risks of acute renal failure and new-onset diabetes after transplantation were observed.

CONCLUSION

Although LC-MS provides a more accurate representation of the blood concentration of the parent compound tacrolimus exclusive of metabolite, established cut points for tacrolimus dosing may need to be adjusted to account for the increased risk of renal injury.

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

BACKGROUND

Various immunoassays have been used for cyclosporine A (CsA) analysis in human whole blood; however, they could not fully satisfy the requirements of criteria for accuracy and specificity in CsA measurement. The liquid chromatography tandem mass spectrometry is a gold method for CsA analysis. The aim of the study was to develop and validate an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for CsA analysis and establish its agreement with an antibody-conjugated magnetic immunoassay (ACMIA) in clinical sample analysis.

METHODS

An UHPLC-MS/MS method for CsA analysis in human whole blood was developed, validated, and applied in 85 samples, which were also tested by ACMIA. The agreement between UHPLC-MS/MS and ACMIA was evaluated by Bland-Altman plot.

RESULTS

The calibration range was 5-2000 ng/mL. The inaccuracy and imprecision were -4.60% to 5.56% and less than 8.57%, respectively. The internal standard-normalized recovery and matrix factor were 100.4%-110.5% and 93.5%-107.6%, respectively. The measurements of ACMIA and UHPLC-MS/MS were strongly correlated (r > 0.98). Evaluated by Bland-Altman plot, the 95% limit of agreement of the ACMIA:UHPLC-MS/MS ratio was 88.7%-165.6%, and the mean bias of the ratio was 21.1%.

CONCLUSIONS

A rapid, simple, accurate, and reliable UHPLC-MS/MS method for CsA analysis in human whole blood was developed, validated, and applied in 85 samples. On average, 21.1% overestimation was observed in ACMIA compared with that in the UHPLC-MS/MS. Further and larger studies are required to identify whether this degree of variance could be accepted by clinicians.

Tacrolimus: A Review of Laboratory Detection Methods and Indications for Use

Tacrolimus (Tac) is an immunosuppressive drug that is used in preventing organ and tissue rejection in patients after transplantation. Tac administration requires frequent and diligent monitoring by physicians to ensure proper dosage and to limit the potential for harmful adverse effects, which can include renal damage, neurotoxicity, and other serious adverse events. Tac is a calcineurin inhibitor, which suppresses the function of T-cells. Its success as an immunosuppressive agent has been well documented in preventing graft-vs-host disease in several types of organ transplants. This literature review will discuss Tac metabolism and its role in preventing tissue and organ transplant rejection. A variety of detection techniques used in the clinical laboratory, including dried-blood-spot analysis, liquid chromatography-tandem mass spectrometry, and immunoassay also will be discussed.

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.