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* = Presenting author

P248 The new infliximab point-of-care quantitative test can equally be used for therapeutic drug monitoring of biosimilars of infliximab

Afonso J.*1,2, Sousa H.T.3, Rosa I.4, Carvalho J.5, Dias C.C.6,7, Magro F.1,2,8

1Faculty of Medicine, University of Porto, Department of Biomedicine, Unit of Pharmacology and Therapeutics, Porto, Portugal 2Centre for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal 3Centro Hospitalar do Algarve, Gastroenterology Department, Portimão, Portugal 4Instituto Português de Oncologia de Lisboa, Gastroenterology Department, Lisboa, Portugal 5Centro Hospitalar de Gaia, Department of Gastroenterology and Hepatology, Vila Nova de Gaia, Portugal 6Center for Health Technology and Services Research, Porto, Portugal 7Faculty of Medicine, University of Porto, Health Information and Decision Sciences Department, Porto, Portugal 8Centro Hospitalar São João, Gastroenterology Department, Porto, Portugal

Background

CT-P13, a biosimilar of the originator infliximab, has been recently approved by the European Medicines Agency (EMA) for the treatment of inflammatory bowel disease (IBD). Therapeutic Drug Monitoring (TDM) is an effective strategy in the management of IBD patients and is widely used in the adjustment of the originator infliximab therapy. A validated point-of-care device for IFX (POC IFX) quantification is already available in the market. The aim of this study was to validate the first point-of-care IFX device for quantification of IFX biosimilar CT-P13 by comparing it with three validated ELISA assays.

Methods

Serum of 184 IBD patients treated with biosimilar infliximab, CT-P13, were analysed for infliximab concentration by POC IFX assay and three ELISA-based established assays. The results were statistically compared both in quantitative and qualitative terms. A statistical analysis of results was performed. Intraclass Correlation Coefficient (ICC) was assessed for quantitative comparison and both accuracy and kappa (95% CI) statistics were used for qualitative analyse. Spiking recovery was also assessed in donors' serum samples spiked with exogenous CT-P13.

Results

Quantitative comparison showed an excellent ICC between POC IFX assay and the three ELISA-based established methods. ICC was 0.907 and 0.935 for POC IFX/in-house and POC IFX/r-biopharm, respectively. For qualitative comparison, accuracy and kappa (95% CI) statistics were determined after stratification of results by therapeutic interval (<3, 3–7 and >7). A good agreement was shown between pairs of assays: POC IFX/in-house showed and accuracy and kappa (95% CI) of 80% and 0.776 [0.177–0.840], respectively. POC IFX/r-biopharm depicted an accuracy and kappa (95% CI) of 88% and 0.874 [0.824–0.922], respectively. POC IFX assay revealed an excellent average spiking recovery percentage (102% [80%-119%]).

Conclusion

POC IFX assay, a methodology already validated and available in the market to assess IFX originator concentration, showed good agreement with both ELISA-based established assays when used to assess IFX biosimilar. This new methodology, that delivers results in 15 min, should be used as a tool in TDM of CT-P13.