title: Trough levels and antibodies to infliximab may not predict response to intensification of infliximab therapy in patients with inflammatory bowel disease.
abstract: BACKGROUND
  Infliximab is effective for the treatment of refractory inflammatory bowel disease (IBD). Nevertheless, up to 40% of patients lose response to infliximab over time. The aim was to assess the clinical value of measuring infliximab trough levels and antibodies to infliximab (ATI) concentrations in IBD patients who lost response to infliximab therapy.
  
  
  METHODS
  We retrospectively studied records of IBD patients who lost response to infliximab therapy. We first assessed clinical responses of different therapeutic strategies that were applied when patients lost response to infliximab and then we looked at the correlation between clinical response and infliximab trough levels and ATI concentrations.
  
  
  RESULTS
  Seventy-six IBD patients were included. 31/76 patients (41%) continued infliximab therapy without any modification, 39 patients (51%) had an intensification of infliximab therapy, five patients (7%) had switched to adalimumab therapy, and one patient (1%) underwent surgery. Clinical response was observed in 27 patients (69%) with an intensification of infliximab therapy. There was no significant difference in mean infliximab trough level at inclusion in patients who responded to intensification of infliximab therapy (3.3 ± 4.1 μg/mL) as compared with patients who did not respond (2.3 ± 2.2 μg/mL, P = 0.85). In all, 16/76 patients (22.4%) presented detectable ATI in the serum. Ten ATI-positive patients had an intensification of infliximab therapy and six (60%) demonstrated a clinical response. After intensification of infliximab therapy the ATI concentration decreased in five patients.
  
  
  CONCLUSIONS
  In patients with IBD who lose response to infliximab, clinical improvement may occur upon intensification of infliximab therapy, irrespective of infliximab serum concentration or presence of ATI.
authors: Hepato-Gastroenterology Department, Saint-Louis Hospital, Université Paris VII, Paris, France.
authors: Benjamin
authors: B
authors: Pariente
authors: Guillaume
authors: G
authors: Pineton de Chambrun
authors: Roman
authors: R
authors: Krzysiek
authors: Marine
authors: M
authors: Desroches
authors: Gauthier
authors: G
authors: Louis
authors: Chiara
authors: C
authors: De Cassan
authors: Clotilde
authors: C
authors: Baudry
authors: Jean-Marc
authors: JM
authors: Gornet
authors: Pierre
authors: P
authors: Desreumaux
authors: Dominique
authors: D
authors: Emilie
authors: Jean-Frédéric
authors: JF
authors: Colombel
authors: Matthieu
authors: M
authors: Allez
mesh_terms: D000068879:Adalimumab; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000097:blood / Q000276:immunology / Q000627:therapeutic use*; D000906:Antibodies / Q000097:blood*; D061067:Antibodies, Monoclonal, Humanized / Q000097:blood / Q000276:immunology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000097:blood / Q000188:drug therapy* / Q000276:immunology*; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
chemical_list: D000893:Anti-Inflammatory Agents; D000906:Antibodies; D061067:Antibodies, Monoclonal, Humanized; D014409:Tumor Necrosis Factor-alpha; D000068879:Adalimumab