title: Infliximab trough levels may predict sustained response to infliximab in patients with Crohn's disease.
abstract: OBJECTIVE
  Over 10% of Crohn's disease (CD) patients annually lose response to infliximab. Infliximab trough levels (TL), concomitant immunosuppressants and endoscopic healing were proposed as predictors of favourable infliximab outcome. We assessed infliximab TL measured after induction therapy as predictors of sustained clinical response. Furthermore, we tried to identify other predictors of long-term benefit of infliximab therapy.
  
  
  METHODS
  We included CD patients treated with infliximab between October 2007 and March 2010 who responded to 3-dose induction followed by maintenance therapy and in whom blood samples taken at treatment week 14 or 22 were available in blood bank. Sustained response to infliximab was defined as absence of treatment failure due to loss of response or drug intolerance.
  
  
  RESULTS
  Eighty four patients were included. Sustained response to infliximab was observed in 47 (56%) patients during a median follow-up of 25 months (14-37). Infliximab TL>3μg/ml were associated with a decreased risk of treatment failure (HR 0.34; 95% CI: 0.16-0.75), whereas the presence of antibodies against infliximab and need for corticosteroids increased this risk (HR 4.34; 95% CI: 1.51-12.5 and HR 2.49, 95% CI: 1.08-5.73, respectively). No impact of concomitant thiopurines was observed, although patients receiving thiopurines had higher infliximab TL than those without immunomodulators (5.51 vs. 0.71μg/ml; p=0.01).
  
  
  CONCLUSIONS
  During a median follow up of 2 years sustained response to infliximab was observed in slightly more than half of CD patients. Infliximab TL>3μg/ml at the start of maintenance regime were predicative of sustained response to infliximab.
authors.affiliation: 1st Faculty of Medicine, Charles University in Prague, Czech Republic. mbortlik@seznam.cz
authors.forename: Martin
authors.initials: M
authors.lastname: Bortlik
authors.forename: Dana
authors.initials: D
authors.lastname: Duricova
authors.forename: Karin
authors.initials: K
authors.lastname: Malickova
authors.forename: Nadezda
authors.initials: N
authors.lastname: Machkova
authors.forename: Eva
authors.initials: E
authors.lastname: Bouzkova
authors.forename: Ludek
authors.initials: L
authors.lastname: Hrdlicka
authors.forename: Arnost
authors.initials: A
authors.lastname: Komarek
authors.forename: Milan
authors.initials: M
authors.lastname: Lukas
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000097:blood* / Q000627:therapeutic use*; D000906:Antibodies / Q000097:blood; D000911:Antibodies, Monoclonal / Q000097:blood* / Q000276:immunology / Q000627:therapeutic use*; D002097:C-Reactive Protein / Q000378:metabolism; D003424:Crohn Disease / Q000188:drug therapy* / Q000601:surgery; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D000069285:Infliximab; D060046:Maintenance Chemotherapy; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D013997:Time Factors; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000906:Antibodies; D000911:Antibodies, Monoclonal; D007166:Immunosuppressive Agents; D002097:C-Reactive Protein; D000069285:Infliximab