P693 Development and evaluation of i-TRACKER infliximab and i-TRACKER anti-Infliximab kits: fast and innovative chemiluminescent assays for the monitoring of patients treated with infliximab

G. Noguier1, C. Montaillier1, S. Daviere2, L. Colombeau1, E. Parussini1

1Theradiag, Research and Development, Croissy-Beaubourg, France, 2Theradiag, Theranostics, Croissy-Beaubourg, France

Background

Infliximab, a monoclonal antibody directed against TNFα, is a drug widely used for the treatment of inflammatory diseases (rheumatoid arthritis, Crohn’s disease, etc.). Therapeutic drug monitoring is currently proposed to provide useful information to clinicians to improve the efficacy of the treatment. Theradiag has just developed the innovative i-TRACKER Infliximab and i-TRACKER Anti-Infliximab kits: fast quantifications of Infliximab and Anti-Infliximab antibodies fully automated on the random access i-TRACK10 chemiluminescent analyser.

Methods

Analytical performances were assessed using two types of serum samples: human serum spiked with Infliximab or Anti-Infliximab antibodies, and samples from inflammatory bowel disease patients treated with Infliximab (n = 41). On one hand, Infliximab from serum sample was captured by TNFα coupled magnetic microparticles and Anti-Infliximab polyclonal antibodies conjugated to acridinium ester were used for the detection of Infliximab. On the other hand, Anti-Infliximab antibodies were captured according to Infliximab coupled magnetic microparticles and detected with the use of Infliximab conjugated to acridinium ester. Light emission was linked to the quantity of Infliximab, or anti-Infliximab antibodies, presents in the sample.

Results

Infliximab measurement showed high accuracy (recovery was comprised between 80% and 107%). High precisions were reached for both assays (intra-precision CV were below 8.1% and 2.7% for Infliximab and Anti-Infliximab assays; inter-precision CV were below 11.7% and 4.8% for Infliximab and Anti-Infliximab assays) and no interferences were seen with biologic agents (bilirubin, haemoglobin, lipids, biotin and rheumatoid factors). The dynamic ranges of the assays were 0.3–24 µg/ml for Infliximab quantification and 10–2000 ng/ml for Anti-Infliximab antibodies quantification. i-TRACKER Infliximab and i-TRACKER anti-Infliximab assays were compared with respective LISA-TRACKER assays and showed excellent correlation (R² = 0.94, Slope = 1.04 for Infliximab assay; Spearman’s coefficient correlation was 0.98 for Anti-Infliximab assay).

Conclusion

i-TRACKER kits are innovative assays which exhibit fast (time to results <40 min), accurate (standardised with NIBSC/WHO international standard Infliximab) and reproducible results for the quantification of princeps and biosimilar molecules (CT-P13, SB2). Excellent agreements were observed with respective LISA-TRACKER assays. i-TRACKER kits are valuable tools for the monitoring of patients treated with Infliximab.