title: Serum trough infliximab levels: A comparison of three different immunoassays for the monitoring of CT-P13 (infliximab) treatment in patients with inflammatory bowel disease.
abstract: BACKGROUND
  CT-P13 is a biosimilar drug of reference infliximab and is approved in some countries for use in some indications for which reference infliximab is approved, including inflammatory bowel disease (IBD). The CT-P13 formulation is identical to that of reference infliximab and has similar physiochemical characteristics. However, even a small molecular distinction could lead to different behavior of CT-P13 in immunoanalytical detection systems.
  
  
  OBJECTIVE
  To determine the correlation between three different enzyme-linked immunosorbent assays for infliximab detection in the measurement of CT-P13 trough serum levels.
  
  
  METHODS
  Serum samples (n = 42) from IBD patients (n = 22) treated with CT-P13 Remsima™ (Celltrion, Korea) were evaluated in a blinded way in infliximab assays manufactured by (A) Matriks Biotek (Turkey), (B) Theradiag (France), and (C) R-Biopharm (Germany).
  
  
  RESULTS
  All assays showed excellent qualitative correlation (Cohen's kappa = 0.90 for A vs. B, 0.76 for A vs. C, and 0.83 for B vs. C). A linear quantitative correlation was satisfactory as well (Spearman's r = 0.91 for A vs. B, 0.86 for A vs. C and 0.92 for B vs. C). Assay C did not detect CT-P13 in 6 samples detected by A and/or B.
  
  
  CONCLUSIONS
  There is a good correlation of CT-P13 serum level detection between these assays.
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Medical Faculty and General Teaching Hospital, Charles University, Karlovo náměstí 32, 121 11, Prague, Czech Republic. Electronic address: karin.malickova@vfn.cz.
authors.forename: Karin
authors.initials: K
authors.lastname: Malíčková
authors.affiliation: IBD Clinical and Research Centre, Iscare a.s., Jankovcova 1569/2c, 170 00 Prague, Czech Republic; Institute of Pharmacology, 1st Medical Faculty, Charles University, Albertov 4, 128 00 Prague, Czech Republic.
authors.forename: Dana
authors.initials: D
authors.lastname: Ďuricová
authors.affiliation: IBD Clinical and Research Centre, Iscare a.s., Jankovcova 1569/2c, 170 00 Prague, Czech Republic; Department of Internal Medicine, Military Hospital, Charles University, U vojenské nemocnice 1200, 169 02 Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Bortlík
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Medical Faculty and General Teaching Hospital, Charles University, Karlovo náměstí 32, 121 11, Prague, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Hind'oš
authors.affiliation: IBD Clinical and Research Centre, Iscare a.s., Jankovcova 1569/2c, 170 00 Prague, Czech Republic.
authors.forename: Naděžda
authors.initials: N
authors.lastname: Machková
authors.affiliation: IBD Clinical and Research Centre, Iscare a.s., Jankovcova 1569/2c, 170 00 Prague, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Hrubá
authors.affiliation: IBD Clinical and Research Centre, Iscare a.s., Jankovcova 1569/2c, 170 00 Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Lukáš
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Medical Faculty and General Teaching Hospital, Charles University, Karlovo náměstí 32, 121 11, Prague, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Zima
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Medical Faculty and General Teaching Hospital, Charles University, Karlovo náměstí 32, 121 11, Prague, Czech Republic; IBD Clinical and Research Centre, Iscare a.s., Jankovcova 1569/2c, 170 00 Prague, Czech Republic.
authors.forename: Milan
authors.initials: M
authors.lastname: Lukáš
mesh_terms: D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D015212:Inflammatory Bowel Diseases / Q000097:blood* / Q000188:drug therapy*; D000069285:Infliximab / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D008297:Male
chemical_list: D000069285:Infliximab
keywords: Biosimilar; CT-P13; Enzyme-linked immunosorbent assay; Inflammatory bowel disease; Infliximab