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P092 Development and evaluation of i-Tracker Ustekinumab and i-Tracker Anti-ustekinumab kits: fast and innovative chemiluminescent assays for the monitoring of patients treated with ustekinumab

Noguier, G.(1);Montaillier, C.(1);Daviere, S.(2);Yang, Y.(2);Colombeau, L.(1);Parussini, E.(1);

(1)Theradiag, Research and Development, Marne la Vallée Cedex 2, France;(2)Theradiag, Theranostics, Marne la Vallée Cedex 2, France

Background

Ustekinumab, a monoclonal antibody directed against IL12/23, is a drug widely used for the treatment of Chronic Inflammatory Diseases (Psoriasis, 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 ustekinumab and i-Tracker Anti-ustekinumab kits: fast quantification of ustekinumab and Anti-ustekinumab antibodies fully automated on the random access i-Track10 chemiluminescent analyzer.

Methods

Analytical performances were assessed using 2 types of serum samples: human serum spiked with ustekinumab or Anti-ustekinumab antibodies, and samples from Inflammatory Bowel Diseases patients treated with ustekinumab (n=32). For drug measurement, ustekinumab from serum sample was captured by anti-idiotypic antibody coupled magnetic microparticles and anti-ustekinumab polyclonal antibodies conjugated to acridinium ester were used for the detection of ustekinumab. For anti-drug antibodies measurement, Anti-ustekinumab antibodies were captured according to Ustekinumab coupled magnetic microparticles and detected with the use of ustekinumab conjugated to acridinium ester. Light emission was linked to the quantity of ustekinumab, or anti-ustekinumab antibodies presents in the sample.

Results

Ustekinumab measurement showed high accuracy (recovery was comprised between 98% and 120%). High precision weas reached for both assays (intra-precision CV were below 9.1% and 5.3% for ustekinumab and Anti-ustekinumab assays ; inter-precision CV were below 4.6% and 10.6% for ustekinumab and Anti-ustekinumab assays) and no interference was seen with biologic agents (bilirubin, hemoglobin, lipids, biotin and rheumatoid factors). The dynamic ranges of the assays were 100ng/ml to 10 000ng/ml for ustekinumab quantification and 1 AU/ml to 250 AU/ml for anti-ustekinumab antibodies quantification. i-Tracker ustekinumab and i-Tracker anti-ustekinumab assays were compared to respective ELISA based LISA-TRACKER assays and showed excellent correlation (R² = 0.96, Slope = 0.93 for ustekinumab assay; Spearman’s coefficient correlation was 0.95 for Anti-ustekinumab assay). 

Conclusion

i-Tracker kits are innovative assays which exhibit fast (time to results < 40min), accurate and reproducible results for the quantification of ustekinumab and Anti-ustekinumab antibodies. Excellent agreements were observed with respective LISA-TRACKER assays. i-Tracker kits are valuable tools for the monitoring of patients treated with ustekinumab.

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