title: Rapid Test for Infliximab Drug Concentration Allows Immediate Dose Adaptation.
abstract: OBJECTIVE
  Therapeutic drug monitoring of infliximab improves treatment outcomes, but available assays to monitor infliximab lack speed to implement treatment algorithms immediately. Our aim is to validate a rapid, lateral flow-based assay (LFA) for quantitative determination of infliximab and to assess thresholds associated with mucosal healing in patients with ulcerative colitis.
  
  
  METHODS
  Samples (n=190) from 29 anti-tumor necrosis factor naive patients with ulcerative colitis starting infliximab induction therapy between June 2010 and February 2012 were prospectively collected. All patients had a Mayo endoscopic sub-score ≥2 at baseline. Mucosal healing (MH), defined as a Mayo endoscopic sub-score ≤1, was evaluated at week 10-14. Infliximab trough concentrations (TC) were determined with a novel LFA, which was benchmarked with the RIDASCREEN infliximab Monitoring (ELISA).
  
  
  RESULTS
  The LFA showed an excellent agreement with enzyme-linked immunosorbent assay (ELISA) for quantification of infliximab, as observed from Pearson and intraclass correlation coefficients of 0.95 and 0.95 during induction and 0.93 and 0.87 during maintenance therapy, respectively. In total, 45% of patients achieved MH. Using the LFA, week 14 TC ≥2.1 μg/ml (AUROC: 0.819, P=0.008) were associated with MH. After 2 years follow-up, 77% of patients with MH were still receiving infliximab therapy vs. 25% of patients without MH.
  
  
  CONCLUSIONS
  We validated a LFA for quantification of infliximab and identified TC associated with MH. With a time-to-result of 20 min, individual sample analysis and user-friendliness, the LFA outplays ELISA as a rapid, accurate tool to monitor infliximab concentrations.
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Therapeutic and Diagnostic Antibodies, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Van Stappen
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Therapeutic and Diagnostic Antibodies, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Lize
authors.initials: L
authors.lastname: Bollen
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Therapeutic and Diagnostic Antibodies, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Niels
authors.initials: N
authors.lastname: Vande Casteele
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Therapeutic and Diagnostic Antibodies, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Papamichael
authors.affiliation: Translational Research in Gastrointestinal Disorders, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Gert
authors.initials: G
authors.lastname: Van Assche
authors.affiliation: Translational Research in Gastrointestinal Disorders, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Ferrante
authors.affiliation: Translational Research in Gastrointestinal Disorders, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Séverine
authors.initials: S
authors.lastname: Vermeire
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Therapeutic and Diagnostic Antibodies, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: Gils