Volumetric Absorptive Microsampling (VAMS) technology for IGF-1 quantification by automated chemiluminescent immunoassay in dried blood

Detection of doping substances in paired dried blood spots and urine samples collected during doping controls in Danish fitness centers

The use of dried blood spot (DBS) in anti-doping can be advantageous in terms of collection, transportation, and storage compared with the traditional anti-doping testing matrices urine and venous blood. There could, nonetheless, be disadvantages such as shorter detection windows for some substances compared with urine, but real-life comparison of the detectability of prohibited substances in DBS and urine is lacking. Herein, we present a liquid chromatography-high resolution mass spectrometry (LC-HRMS)-based screening method for simultaneous detection of 19 target analytes from the doping substance categories S1-S5 in a single spot. Ninety-eight urine and upper-arm DBS (Tasso-M20) sample pairs were collected from fitness centers customers notified for doping control by Anti Doping Denmark, and three sample pairs were collected from active steroid users undergoing clinical evaluation and treatment at a Danish hospital. The analytical findings were cross compared to evaluate the applicability of the developed DBS testing menu in terms of feasibility and analytical performance. To our knowledge, this is the first study to compare the detectability of prohibited substances in DBS and urine samples collected in a doping control setting. Twenty-seven of the urine samples and 23 DBS samples were positive, and we observed a very high concordance (95%) in the overall analytical results (i.e., positive or negative samples for both urine and DBS). Collectively, these results are very promising, and DBS seems suitable as a stand-alone matrix in doping control in fitness centers likely because of the high analyte concentration levels in these samples.

Analytical and Clinical Validation of Assays for Volumetric Absorptive Microsampling (VAMS) of Drugs in Different Blood Matrices: A Literature Review

Volumetric absorptive microsampling (VAMS) is the newest and most promising sample-collection technique for quantitatively analyzing drugs, especially for routine therapeutic drug monitoring (TDM) and pharmacokinetic studies. This technique uses an absorbent white tip to absorb a fixed volume of a sample (10-50 µL) within a few seconds (2-4 s), is more flexible, practical, and more straightforward to be applied in the field, and is probably more cost-effective than conventional venous sampling (CVS). After optimization and validation of an analytical method of a drug taken by VAMS, a clinical validation study is needed to show that the results by VAMS can substitute what is gained from CVS and to justify implementation in routine practice. This narrative review aimed to assess and present studies about optimization and analytical validation of assays for drugs taken by VAMS, considering their physicochemical drug properties, extraction conditions, validation results, and studies on clinical validation of VAMS compared to CVS. The review revealed that the bio-analysis of many drugs taken with the VAMS technique was optimized and validated. However, only a few clinical validation studies have been performed so far. All drugs that underwent a clinical validation study demonstrated good agreement between the two techniques (VAMS and CVS), but only by Bland-Altman analysis. Only for tacrolimus and mycophenolic acid were three measurements of agreement evaluated. Therefore, VAMS can be considered an alternative to CVS in routine practice, especially for tacrolimus and mycophenolic acid. Still, more extensive clinical validation studies need to be performed for other drugs.

New perspectives for the therapeutic drug monitoring of tacrolimus: Quantification in volumetric DBS based on an automated extraction and LC-MS/MS analysis

Volumetric microsampling devices have been developed for home-based capillary blood sampling and are now increasingly proposed for the therapeutic drug monitoring (TDM) of immunosuppressive drugs. Our objective was to validate a LC-MS/MS method for tacrolimus quantification based on both a manual and an automated extraction of dried blood spots (DBS) collected with a volumetric microsampling device. DBS collection was performed by placing a drop of whole blood (WB) pre-spiked with tacrolimus onto a sealing film and placing the hemaPEN® device (Trajan Scientific and Medical, Melbourne, Australia) into the drop according to the device specifications. Tacrolimus was quantified using a fully automatic preparation module connected to a LCMS system (CLAM-3020® and LCMS-8060®, Shimadzu, Marne-la-Vallée, France). The method was validated analytically and clinically in accordance with the EMA and IATDMCT guidelines. The method was linear from 1 to 100 µg/L. Within- and between-run accuracy and precision fulfilled the validation criteria (biases and imprecision <15% or 20% for the lower limit of quantification). No hematocrit effect, matrix effect or carry-over was observed. No selectivity issue was identified and dilution integrity was confirmed. Tacrolimus in DBS was stable for 14 days at room temperature and +4°C, and for 72h at +60°C. There was a good correlation between tacrolimus concentrations measured in WB and in DBS of 20 kidney and liver transplant recipients (r=0.93 and 0.87, for manual and automated extraction respectively). A method for tacrolimus measurement in DBS collected with volumetric micro-sampling device, based on a fully automated process from pre-treatment to LC-MS/MS analysis was developed and validated according to analytical and clinical criteria. This performing sampling and analytical procedure opens the perspective of an easier, faster and more efficient TDM of tacrolimus for patients, clinicians and laboratories.

Capillary blood as a complementary matrix for doping control purposes. Application to the definition of the individual longitudinal profile of IGF-1

We present a novel procedure to monitor the fluctuations of the levels of IGF-1 in capillary blood in the framework of doping control analysis. Being an endogenous hormone, direct methods are not applicable, so the most effective way to detect the intake of the exogenous hormone would be based on the longitudinal monitoring of the athlete. We have therefore followed the individual variability, in four subjects (two males and two females), of the levels of IGF-1 in capillary blood samples collected three times per day for five days, then once a week for at least two months. Analyses were performed by liquid chromatography coupled to tandem mass spectrometry following a bottom-up approach. The whole protocol, from the sample collection to the instrumental analysis, was validated according to the World Anti-Doping Agency's guidelines and ISO17025. The analytical protocol showed to be fit for purpose in terms of sensitivity (LOD 25 ng/mL and LOI 35 ng/mL), selectivity (no interferences were detected at the retention time of IGF-1 and the internal standard), and repeatability (CV<10%). The linearity was confirmed in the range of 50-1000 ng/mL (correlation coefficient R² >0.995, with a % relative bias of the experimental concentration of the different calibrators used for the estimation of the linearity lower than 20% for the lowest level and than 15% for the other levels). Stability studies were also performed, also to establish the optimal conditions for transport and storage: samples were stable at 4 °C for up to 72 h and at -20 °C and -80 °C for up to three months. Our preliminary results indicate that, in all subjects, the levels of IGF-1 did not present significant circadian fluctuations and remained stable during the entire period of the study (2-3 months, depending on the subject). The stability over time of IGF-1 levels in capillary blood indicates the possibility of detecting the intake of the non-endogenous hormone based on a longitudinal approach, as it is modeled in the framework of the endocrinological module of the athlete biological passport.

Applications of Volumetric Absorptive Microsampling Technique: A Systematic Critical Review

METHODS

A novel microsampling device called Volumetric Absorptive microsampling (VAMS), developed in 2014, appears to have resolved the sample inhomogeneity inherent to dried blood spots, with improved precision in the volume of sample collected for measuring drug concentration. A literature search was conducted to identify several analytical and pharmacokinetic studies that have used VAMS in recent years.

RESULTS

The key factors for proper experimental design and optimization of the extraction of drugs and metabolites of interest from the device were summarized. This review focuses on VAMS and elaborates on bioanalytical factors, method validation steps, and scope of this technique in clinical practice.

CONCLUSIONS

The promising microsampling method VAMS is especially suited for conducting pharmacokinetic studies with very small volumes of blood, especially in special patient populations. Clinical validation of every VAMS assay must be conducted prior to the routine practical implementation of this method.

Microsampling: A role to play in Covid-19 diagnosis, surveillance, treatment and clinical trials

The outbreak of the new coronavirus disease changed the world upside down. Every day, millions of people were subjected to diagnostic testing for Covid-19, all over the world. Molecular tests helped in the diagnosis of current infection by detecting the presence of viral genome whereas serological tests helped in detecting the presence of antibody in blood as well as contributed to vaccine development. This testing helped in understanding the immunogenicity, community prevalence, geographical spread and conditions post-infection. However, with the contagious nature of the virus, biological specimen sampling involved the risk of transmission and spread of infection. Clinic or pathology visit was the most concerning part. Trained personnel and resources was another barrier. In this scenario, microsampling played an important role due to its most important advantage of remote, contactless, small volume and self-sampling. Minimum requirements for sample storage and ease of shipment added value in this situation. The highly sensitive instruments and validated assay formats assured the accuracy of results and stability of samples. Microsampling techniques are contributing effectively to the Covid-19 pandemic by reducing the demand for clinical staff in population-level testing. The validated and established applications supported the use of microsampling in diagnosis, therapeutic drug monitoring, development of treatment or vaccines and clinical trials for Covid-19.

EPO transgene detection in dried blood spots for antidoping application

The modification of gene expression to treat diseases is a field of research with exponential growth. As doping in sport closely follows emerging therapies, a surveillance of the modification of gene expression to enhance performance is needed. The gene coding for erythropoietin (EPO) is one target of interest. Since 2010, several protocols have been proposed to identify EPO gene doping by focusing on the presence in blood of a transgene that differ in size from the endogenous gene sequence, normally found in the human DNA. In this work, our aim was to validate an easily applicable method for EPO gene doping detection in dried blood spots (DBS). We evaluated the detection of EPO transgene in 20-μl DBS after the spike of a plasmid carrying the EPO transgene in whole blood. Three different DBS were compared: Nucleic-Card™, Whatman® 903, and the volumetric 20-μl VAMS™. Detection was performed with real-time polymerase chain reaction (PCR) and validated with two Taqman assays (one commercial and one custom) specific for the EPO transgene. The initial testing procedure could be done using one assay (custom) and the confirmation using the second one (commercial Taqman) with a final check of the size of the PCR product. Starting from 20-μl dried blood, 1000 copies of EPO transgene could efficiently be detected with the three types of DBS, VAMS showing a slightly better sensitivity. No loss of sensitivity was observed after 1-month storage of DBS at room temperature. This method could be applied to DBS collected during doping controls and allows reanalysis.

Whole blood stability evaluation of monoclonal antibody therapeutics using volumetric absorptive microsampling

Volumetric absorptive microsampling (VAMS) is increasingly utilized for both nonclinical and clinical pharmacokinetic studies. Currently, VAMS is employed as the sampling method for the detection of antibodies for coronavirus disease 2019. Biotherapeutics whole blood stability on VAMS presents as a critical concern for the health and pharmaceutical industries. In this follow-up to our previous publication, we evaluated daclizumab and trastuzumab whole blood sample stability on VAMS. The drug recovery data we observed at room temperature for short term and -80°C for long term was very encouraging. The knowledge could help us better understand and plan important investigation timelines, especially pandemic situations where human whole blood samples from a large population are collected and in urgent need of data analysis.

Adaptation of Elecsys® anti-severe acute respiratory syndrome coronavirus-2 immunoassay to dried blood spots: proof of concept

Aim: Several automated immunoassays have been validated on serum/plasma to evaluate the presence of significant levels of anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) antibodies, signs of a present or past infection, but the use of dried blood spots (DBS) would facilitate sampling, shipping and storage. Objective: The aim of this project was to give proof of concept of the possibility to use of the automatized Elecsys^® anti-SARS-CoV-2 immunoassay with a volumetric DBS device. Results: Linearity and correlation were satisfactory between volumetric DBS and plasma. A cut-off value was suggested and should be validated with more samples. Conclusion: this study strongly support the possibility to work with volumetric DBS instead of serum/plasma to test for anti-SARS-CoV-2 antibodies.

Annual banned-substance review: Analytical approaches in human sports drug testing 2019/2020

Analytical chemistry-based research in sports drug testing has been a dynamic endeavor for several decades, with technology-driven innovations continuously contributing to significant improvements in various regards including analytical sensitivity, comprehensiveness of target analytes, differentiation of natural/endogenous substances from structurally identical but synthetically derived compounds, assessment of alternative matrices for doping control purposes, and so forth. The resulting breadth of tools being investigated and developed by anti-doping researchers has allowed to substantially improve anti-doping programs and data interpretation in general. Additionally, these outcomes have been an extremely valuable pledge for routine doping controls during the unprecedented global health crisis that severely affected established sports drug testing strategies. In this edition of the annual banned-substance review, literature on recent developments in anti-doping published between October 2019 and September 2020 is summarized and discussed, particularly focusing on human doping controls and potential applications of new testing strategies to substances and methods of doping specified the World Anti-Doping Agency's 2020 Prohibited List.

Use of capillary dried blood for quantification of intact IGF-I by LC–HRMS for antidoping analysis

Background: IGF-I is used as a biomarker to detect Growth Hormone doping in athletes’ blood samples. Objective: Our aim was to develop and validate a fast, high-throughput and accurate quantification of intact IGF-I from volumetric absorptive microsampling (VAMS) dried blood using LC coupled to high resolution mass spectrometry (LC–HRMS). Methodology & results: IGF-I was extracted from the VAMS, released from its binding proteins, concentrated using microelution SPE and analyzed by LC–HRMS. The method was successfully validated in accordance with the World Anti-Doping Agency's requirements. Subsequently, IGF-I measurements from capillary dried blood and serum were compared. Conclusion: The combination of VAMS, microelution SPE and LC–HRMS is a promising strategy applicable to IGF-I quantification in athletes’ samples.