title: A rapid assay for on-site monitoring of infliximab trough levels: a feasibility study.
abstract: Monitoring levels of biologicals against tumor necrosis factor (TNF) has been suggested to improve therapeutic outcomes in inflammatory bowel diseases (IBDs). This pilot study describes a rapid lateral flow (LF)-based assay for on-site monitoring of serum trough levels of humanized monoclonal antibody infliximab (IFX). The applied chromatographic method utilizes sequential flows of diluted serum, wash buffer, and an immunoglobulin generic label on LF strips with a Test line comprised of TNF-α. The successive flows permitted enrichment of IFX at the Test line before the label was applied. The label, luminescent upconverting phosphor (UCP) particles coated with protein-A, emits a 550-nm visible light upon excitation with 980-nm infrared light. IFX concentrations were determined through measurement of UCP fluorescence at the Test line. The assay was optimized to detect IFX levels as low as 0.17 μg/mL in serum. For patients with IBD, this limit is appropriate to detect levels associated with loss of response (0.5 μg IFX/mL). The assay was evaluated with clinical samples from patients with Crohn's disease and correlated well within the physiologically relevant range from 0.17 to 10 μg/mL with an IFX-specific ELISA. Performance of the assay was further successfully validated with samples from blood donors, IFX negative IBD patients, and rheumatoid arthritis patients that had developed anti-IFX antibodies. Because of its generic nature, the assay is suited for detecting most therapeutic anti-TNF-α monoclonal antibodies.
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20 Bldg 2, PO Box 9600, 2300 RC, Leiden, The Netherlands. P.Corstjens@LUMC.NL
authors.forename: Paul L A M
authors.initials: PL
authors.lastname: Corstjens
authors.forename: Herma H
authors.initials: HH
authors.lastname: Fidder
authors.forename: Karien C
authors.initials: KC
authors.lastname: Wiesmeijer
authors.forename: Claudia J
authors.initials: CJ
authors.lastname: de Dood
authors.forename: Theo
authors.initials: T
authors.lastname: Rispens
authors.forename: Gert-Jan
authors.initials: GJ
authors.lastname: Wolbink
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Hommes
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Tanke
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000097:blood / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000097:blood* / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000276:immunology; D001681:Biological Assay / Q000379:methods* / Q000592:standards; D003424:Crohn Disease / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D005240:Feasibility Studies; D006801:Humans; D000069285:Infliximab; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000379:methods* / Q000592:standards; D010758:Phosphorus / Q000737:chemistry; D011485:Protein Binding; D013194:Staining and Labeling; D013205:Staphylococcal Protein A / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000097:blood
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D013205:Staphylococcal Protein A; D014409:Tumor Necrosis Factor-alpha; D010758:Phosphorus; D000069285:Infliximab