Detection of infliximab levels and anti-infliximab antibodies: a comparison of three different assays

• Published in: Alimentary pharmacology & therapeutics Vol. 36; no. 8; pp. 765 - 771
• Main Authors: Vande Casteele, N., Buurman, D. J., Sturkenboom, M. G. G., Kleibeuker, J. H., Vermeire, S., Rispens, T., van der Kleij, D., Gils, A., Dijkstra, G.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.10.2012; Blackwell
• Subjects: Anti-Inflammatory Agents, Non-Steroidal - blood; Anti-Inflammatory Agents, Non-Steroidal - immunology; Antibodies - blood; Antibodies, Monoclonal - blood; Antibodies, Monoclonal - immunology; Antigen-Antibody Reactions; Biological and medical sciences; Biomarkers - blood; Digestive system; False Positive Reactions; Gastroenterology. Liver. Pancreas. Abdomen; Humans; Immunoassay - methods; Infliximab; Medical sciences; Pharmacology. Drug treatments; Reagent Kits, Diagnostic - standards; Statistics as Topic; Immunomodulator; Infliximab; Anticytokine; Cytokine; Antipsoriatic agent; Monoclonal antibody; Diagnosis; Immunosuppressive agent; Detection; Anti-Tumor Necrosis Factor-alpha; Tumor necrosis factor α; Comparative study
• ISSN: 0269-2813; 1365-2036
• DOI: 10.1111/apt.12030

Summary Background Formation of antibodies to infliximab (ATI) inversely correlates with functional drug levels and clinical outcome. Comparison of drug levels and anti‐drug antibody monitoring is hampered by lack of standardisation. Aim To determine the correlation between three different assays for measuring infliximab and ATI. Methods Serum samples and spiked controls (total 62) were evaluated in a blinded way in infliximab and ATI assays developed by Sanquin Amsterdam, Netherlands (A), Laboratory for Pharmaceutical Biology, KU Leuven, Belgium (B) and a commercially available kit from Biomedical Diagnostics (BMD), Paris, France (C) performed by the University Medical Center Groningen (UMCG), Netherlands. Results All infliximab assays showed a linear quantitative correlation (Pearson r = 0.91 for A vs. B, 0.83 for A vs. C and 0.73 for B vs. C). Assay C detected infliximab in 11 samples (18%) not detected by A and B, including samples containing only ATI. All ATI assays showed a good linear correlation (Pearson r = 0.95 for A vs. B, 0.99 for A vs. C and 0.97 for B vs. C). Assay A detected ATI in five samples with low ATI that were not detected by assays B and C. Assay B did not detect ATI in three patient samples with low ATI according to assays A and C. Conclusions There is a good correlation of infliximab and antibodies to infliximab measurements between these assays. Nevertheless, the Biomedical Diagnostics kit detected false positive infliximab levels in 18% of the samples.