DOP031 Subtherapeutic serum infliximab trough levels and complete mucosal healing are associated with sustained clinical remission after infliximab discontinuation in paediatric Crohn's disease patients

Abstract

Background/Aims There is limited data regarding the clinical course of Crohn's disease (CD) after discontinuing infliximab (IFX) treatment in the pediatric population. We aimed to investigate the outcome of pediatric CD patients who had discontinued IFX under clinical remission by combined immunosuppression with IFX, and to reveal risk factors associated with clinical relapse in these patients. Methods We conducted a retrospective observational study from January 2009 to June 2016 at the Department of Pediatrics, Samsung Medical Center. The subjects were 63 patients who had discontinued scheduled IFX under sustained corticosteroid-free clinical remission for at least 1 year by combined immunosuppression with IFX and azathioprine, and had been followed for at least 1 year after IFX cessation. Relapse free survival rate and the median time to relapse was estimated by Kaplan-Meier survival analysis. Demographic, clinical, biochemical, and endoscopic factors at IFX cessation were evaluated for their association with clinical relapse using Cox proportional hazard regression analysis. Results After a median follow-up period of 4.3 years (range: 1-7.5 years), 60% (38/63) patients had experienced a clinical relapse. The estimated cumulative relapse rate for 1-, 2-, 4-years were 19%, 36%, and 62%, and the median relapse time was 3.3 years from IFX cessation. According to multivariable Cox proportional hazard regression analysis, serum IFX trough levels of >=2.5 mug/mL and incomplete mucosal healing status were associated with clinical relapse (HR=7.199, 95% CI=1.641-31.571, p=0.009, and HR=3.628, 95% CI=1.608-8.185, p=0.002, respectively). Retreatment with IFX was effective in 33 patients (92%). Conclusions Approximately 50% of patients with pediatric luminal CD under sustained clinical remission for at least 1 year by combined immunosuppression will experience a relapse within 3.3 years after IFX cessation. A subgroup of patients with subtherapeutic serum IFX trough levels and a complete mucosal healing status at IFX cessation may better sustain clinical remission under thiopurines after IFX discontinuation.