Validation of a Capillary Dry Blood Sample MITRA-Based Assay for the Quantitative Determination of Systemic Tacrolimus Concentrations in Transplant Recipients

A Systematic Literature Review on the Use of Dried Biofluid Microsampling in Patients With Kidney Disease

BACKGROUND

Kidney disease is fairly unique due to the lack of symptoms associated with disease activity, and it is therefore dependent on biological monitoring. Dried biofluids, particularly dried capillary blood spots, are an accessible, easy-to-use technology that have seen increased utility in basic science research over the past decade. However, their use is yet to reach the kidney patient population clinically or in large-scale discovery science initiatives. The aim of this study was to systematically evaluate the existing literature surrounding the use of dried biofluids in kidney research.

METHODS

A systematic literature review was conducted using three search engines and a predefined search term strategy. Results were summarised according to the collection method, type of biofluid, application to kidney disease, cost, sample stability and patient acceptability.

RESULTS

In total, 404 studies were identified and 67 were eligible. In total, 34,739 patients were recruited to these studies with a skew towards male participants (> 73%). The majority of samples were blood, which was used either for monitoring anti-rejection immunosuppressive drug concentrations or for kidney function. Dried biofluids offered significant cost savings to the patient and healthcare service. The majority of patients preferred home microsampling when compared to conventional monitoring.

CONCLUSION

There is an unmet need in bringing dried microsampling technology to advance kidney disease despite its advantages. This technology provides an opportunity to upscale patient recruitment and longitudinal sampling, enhance vein preservation and overcome participation bias in research.

Use of volumetric absorptive microsampling and parallel reaction monitoring mass spectrometry for tacrolimus blood trough measurements at home in pediatric heart transplant patients

Background

Measurement of trough levels for calcineurin inhibitors by venipuncture sampling is a mainstay of patient management in solid organ transplant recipients but challenging in pediatric patients. Volumetric Absorptive Microsampling (VAMS) is a patient-friendly, minimally invasive sampling technique to accurately collect blood. An assay for measurement of tacrolimus in blood using VAMS, coupled with parallel reaction monitoring (PRM) mass spectrometry, was validated in pediatric heart transplant patients.

Methods

Tacrolimus was measured by a newly developed high-resolution PRM assay and compared with low-resolution tandem mass spectrometry (MRM). Dried blood samples were collected from pediatric heart transplant patients (n = 35) using VAMS devices and a satisfaction survey was completed by patients/guardians. Tacrolimus concentrations were compared across whole liquid blood, dried blood spots, and capillary blood, and shipping stability determined.

Results

The PRM assay was linear over a range 1-50 ng/mL, similar to MRM but had greater specificity due to reduced background noise. No significant differences in tacrolimus concentrations were observed between VAMS and venous blood. Tacrolimus dried on VAM tips was stable for 14 days and concentrations were unaffected by postal shipping. The variability in two simultaneously collected at-home patient samples was minimal - average concentration difference was 0.12 ± 0.94 ng/mL (p = 0.6) between paired samples.

Conclusion

A high resolution PRM mass spectrometry assay was developed for home-based dried blood collections for therapeutic monitoring of tacrolimus. The advantage of PRM was enhanced specificity and the VAMS devices provided a simple and convenient approach to blood sampling at home in pediatric heart transplant patients.

Validation of low-volume sampling devices for pharmacokinetic analysis: technical and logistical challenges and solutions

While low-volume sampling technologies offer numerous advantages over venipuncture, implementation in clinical trials poses technical and logistical challenges. Bioanalytical methods were validated for measuring the concentration of crenezumab and etrolizumab in dried blood samples collected using Mitra and Tasso-M20. The data generated demonstrate that the concentrations of crenezumab and etrolizumab in dried blood collected by either device could be determined using calibrators prepared in serum. Drug concentrations from dried blood were converted to serum concentrations using patient hematocrit levels. Contract Research Organization experience in sample handling and analysis allowed us to compare differences between various low-volume sampling technologies. This study evaluated challenges and presented potential solutions for use of different low-volume sampling technologies for pharmacokinetic analysis.

Volumetric microsampling for simultaneous remote immunosuppressant and kidney function monitoring in outpatient kidney transplant recipients

AIMS

Immunosuppressant and kidney function monitoring are crucial for kidney transplant recipient follow-up. Microsamples enable remote sampling and minimise patient burden as compared to conventional venous sampling at the clinic. We developed a liquid chromatography-tandem mass spectrometry assay to quantify tacrolimus, mycophenolic acid (MPA), creatinine and iohexol in dried blood spot (DBS), and volumetric absorptive microsample (VAMS) samples.

METHODS

The assay was successfully validated analytically for all analytes. Clinical validation was conducted by direct comparison of paired DBS, VAMS and venous reference samples from 25 kidney transplant recipients. Patients received iohexol 5-15 minutes before immunosuppressant intake and were sampled 0, 1, 2 and 3 hours thereafter, enabling tacrolimus and MPA area under the concentration-time curve (AUC) and creatinine-based and iohexol-based glomerular filtration rate (GFR) estimation. Method agreement was evaluated using Passing-Bablok regression, Bland-Altman analysis and the percentages of values within 15-30% of the reference (P₁₅ -P₃₀ ) with a P₂₀ acceptance threshold of 80%.

RESULTS

For DBS samples, method agreement was excellent for tacrolimus trough concentrations (n = 25, P₁₅  = 92.0%) and AUCs (n = 25; P₂₀  = 95.8%) and adequate for creatinine-based GFR trend monitoring (n = 25; P₂₀  = 80%). DBS-based MPA AUC assessment showed suboptimal agreement (n = 16; P₂₀  = 68.8%), but was considered acceptable given its P₃₀ of 100%. The assay performed inadequately for DBS-based iohexol GFR determination (n = 24; P₂₀  = 75%). The VAMS technique generally showed inferior performance, but can be considered for certain situations.

CONCLUSION

The assay was successfully validated for tacrolimus, MPA and creatinine quantification in DBS samples, enabling simultaneous remote kidney function trend monitoring and immunosuppressant therapeutic drug monitoring in kidney transplant recipients.

Quantitation of Tacrolimus in Human Whole Blood Samples Using the MITRA Microsampling Device

BACKGROUND

The calcineurin inhibitor tacrolimus is a narrow therapeutic index medication, which requires therapeutic drug monitoring to optimize dose on the basis of systemic exposure. MITRA microsampling offers a minimally invasive approach for the collection of capillary blood samples from a fingerprick as an alternative to conventional venous blood sampling for quantitation of tacrolimus concentrations.

METHODS

A bioanalytical method for the quantitation of tacrolimus in human whole blood samples collected on MITRA tips was developed, using liquid-liquid extraction followed by liquid chromatography with tandem mass spectrometry detection. Validation experiments were performed according to the current Food and Drug Administration and European Medicines Agency guidelines on validation of bioanalytical methods. Validation criteria included assay specificity and sensitivity, interference, carryover, accuracy, precision, dilution integrity, matrix effect, extraction recovery, effect of hematocrit and hyperlipidemia, and stability.

RESULTS

All assay validation results were within the required acceptance criteria, indicating a precise and accurate tacrolimus quantitation method. The validated assay range was 1.00-50.0 ng/mL. No interference, carryover or matrix effect was observed. Extraction recovery was acceptable across the assay range. Samples were stable for up to 96 days at -20°C and 20°C, and 28 days at 40°C. Hematocrit, hyperlipidemia, and lot-to-lot differences in the nominal absorption volume of the 10-μL MITRA tips were shown not to influence tacrolimus quantitation by this assay method.

CONCLUSIONS

The bioanalytical method validated in this study is appropriate and practical for the quantitation of tacrolimus in human whole blood samples collected using the MITRA microsampling device.