Grace van der Gugten (Presenter)
St Paul's Hospital
Authorship: J. Grace van der Gugten (1), Maria A. V. Willrich (2), Mari L. DeMarco (1)(3)
(1) Department of Pathology and Laboratory Medicine, St Paul’s Hospital, Vancouver, Canada (2) Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905 (3) Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
Infliximab (IFX) is an anti-TNF monoclonal antibody therapy used to treat autoimmune disorders such as Crohn’s disease and ulcerative colitis. A significant portion of patients receiving IFX therapy will develop signs of loss of response, making therapeutic drug monitoring necessary for rational therapeutic decision making. Immunometric assays have been routinely used for the measurement of IFX in serum, but do not correlate with one another and share issues common to immunoassays. By contrast, mass spectrometry has the potential to enable harmonization of IFX assays including development of common therapeutic cut-points.
Infliximab (IFX) is a monoclonal antibody therapy used to treat autoimmune disorders such as Crohn’s disease and ulcerative colitis. It inhibits the inflammatory cascade by binding to tumour necrosis factor. A significant portion of patients receiving IFX therapy will develop signs of loss of response to therapy (1). For those experiencing loss of response, IFX therapeutic drug monitoring offers a rational approach to therapeutic decision making and is associated with improved outcomes (2). IFX concentrations help determine if the patient requires dose optimization (escalation), should be switched to another disease-modifying therapeutic, or requires an alternative treatment strategy (e.g. surgery) (1).
Immunometric assays (ELISA, RIA, immunofluorometric) have been routinely used for the measurement of IFX in serum (3). Unfortunately, these assays demonstrate varying degrees of analytical and diagnostic concordance (3,4). This lack of harmonization is problematic both for patient care, and for rapid and accurate dissemination and uptake of research findings (4). By contrast, mass spectrometry has the potential to enable harmonization of testing between laboratories for IFX and use of common cut-points.
An LC-MS/MS assay was developed at St Paul’s Hospital in Vancouver, Canada, to quantitate IFX (5). Method development included pre-digestion and digestion experiments to determine critical steps, optimize workflow and choose optimal peptide(s) for quantitation. Subsequently a simplified, rapid sample preparation workflow was developed and automated on our liquid handler to facilitate translation of the LC-MS/MS assay into routine use in our clinical lab.
Method comparisons were done with the Immunodiagnostik ELISA (n=112) and with Mayo Medical’s LC-MS/MS assay (n=65) (6). Our assay was also compared between two manufacturer’s LC-MS/MS platforms in our own laboratory.
Conclusions & Discussion
A simple, rapid and inexpensive LC-MS/MS IFX assay was implemented in our laboratory at St. Paul’s Hospital. Unlike previous immunoassay comparisons, the LC-MS/MS comparisons we performed showed excellent agreement, with no observed calibration bias. Our laboratories have benchmarked our LC-MS/MS IFX assays against the manufacturer’s reported drugs concentration. In contrast, comparison to the ELISA assay(s) demonstrate that the ELISA method does not meet gravimetric targets. The promising results of this study demonstrate that the use of LC-MS/MS could enable harmonization of IFX therapeutic drug monitoring assays, with the ultimate goal of improving patient care and outcomes.
References & Acknowledgements:
1. Trasolini R and DeMarco ML. ‘Therapeutic drug monitoring of monoclonal antibody infliximab’ ASCP Case Reports, October, 2016.
2. Robert A. Mitchell, Constantin Shuster, Neal Shahidi, et al., ‘The Utility of Infliximab Therapeutic Drug Monitoring among Patients with Inflammatory Bowel Disease and Concerns for Loss of Response: A Retrospective Analysis of a Real-World Experience,’ Canadian Journal of Gastroenterology and Hepatology, vol. 2016, Article ID 5203898, 7 pages, 2016. doi:10.1155/2016/5203898
3. Niels Vande Casteele, Marc Ferrante, Gert Van Assche, et al., ‘Detection of infliximab levels and anti-infliximab antibodies: A comparison of three different assays’ Aliment Pharmacol. Ther 2012; 36:765-771
4. Bader, LI, Sol Solbert, SM, Kaada SH., et al., ‘Assays for Infliximab Drug Levels and Antibodies: A Matter of Scales and Categories’ Scand J Immunol 2017; 86:165-170
5. van der Gugten JG and DeMarco ML. In preparation.
6. Willrich, Maria AV., Murray, David L., Barnidge, David R., et al., ‘Quantitation of infliximab using clonotypic peptides and selective reaction monitoring by LC-MS/MS’ Int Immunopharmacol 2015; 28:513-520
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