P057 Development and evaluation of the i-Tracker Certolizumab and i-Tracker Anti-Certolizumab kits: rapid and innovative tests intended for monitoring patients treated with Certolizumab.
Khater, G.(1)*;Noguier, G.(2);Daviere, S.(1);Guilbert, V.(2);Montaillier, C.(2);
(1)Theradiag, Theranostic, Croissy Beaubourg, France;(2)Theradiag, Research & Development, Croissy Beaubourg, France;
Background
Certolizumab is a human monoclonal antibody directed against TNFα. This drug is commonly used for the treatment of patients with inflammatory diseases such as rheumatoid arthritis, ankylosing spondylitis or even psoriatic arthritis. Currently, monitoring of Certolizumab plasma levels is available and provides clinicians with relevant information to improve treatment efficacy. Theradiag has just developed new rapid (results in less than 40 minutes) and innovative assays allowing the quantification of Certolizumab: these tests are available on the new innovative i-Track10 chemiluminescence platform and allow the rapid quantification of Certolizumab as well as anti-antibody antibodies. -Certolizumab induced by the patient.
Methods
Analytical performance was studied using two types of samples: human serum samples spiked with Certolizumab or anti-Certolizumab antibodies, and human serum samples from patients with inflammatory diseases treated with Certolizumab (n=56 ). For drug assay, Certolizumab was captured using TNFα-coupled magnetic microspheres and detected using an acridinium ester-conjugated anti-Certolizumab polyclonal antibody. For the assay of anti-Certolizumab antibodies, microspheres coupled to Certolizumab were used. The anti-Certolizumab antibodies thus captured were detected by Certolizumab conjugated to the acridinium ester. Light emission from acridinium ester conjugates is directly related to the amount of Certolizumab or anti-Certolizumab antibodies present in the sample.
Results
The quantification of Certolizumab by the i-Tracker Certolizumab kit shows very good accuracy (the percentages of recovery are between 84% and 102%). The intra-test and inter-test reproducibility is very good (CV <4.8% for the Certolizumab assay and CV <10.6% for the anti-Certolizumab antibody assay). No interference from biological agents (bilirubin, hemoglobin, triglycerides, rheumatoid factors) was detected. The assay measurement ranges are 3 µg/mL to 100 µg/mL for Certolizumab and 10 AU/mL to 1500 AU/mL for anti-Certolizumab antibodies. i-Tracker assays were compared to ELISA-based Lisa-Tracker assays. The correlations are excellent: the Certolizumab assay presents an R² = 0.94 and a slope of 0.92, the anti-Certolizumab antibody assay presents a Spearman coefficient of 0.94.