BackgroundReFLECT was a French, prospective, multicenter, observational cohort study evaluating the effectiveness and safety of the infliximab (IFX) biosimilar CT-P13 in a real-world setting. Here, we describe the results for adults with inflammatory bowel disease (IBD). MethodsEligible patients with IBD were recruited and received intravenous CT-P13 induction and/or maintenance therapy; patients were either naive to IFX (IFX-naive) or previously treated with IFX originator or another IFX biosimilar (IFX-switched). The primary objective was CT-P13 persistence, which was measured as a time-dependent variable during a two-year follow-up period with four prespecified visits. Safety was assessed. ResultsThe adult IBD population comprised 530 patients with Crohn's disease (CD), including 327 categorized as IFX-naive, 188 as IFX-switched, 11 as other (i.e., previously received IFX but received another treatment before switching to CT-P13), and 4 with missing data; and 221 patients with ulcerative colitis (UC), including 152 categorized as IFX-naive, 59 as IFX-switched, 8 as other, and 2 with missing data. After two years of follow-up, the rates of CT-P13 persistence were 71.7 % (95 % CI: 66.7, 77.0) and 63.7 % (55.3, 73.3) in patients with CD and UC, respectively. CT-P13 persistence was greater for IFX-switched patients than for IFX-naive patients (CD: 83.7 % [95 % CI: 78.0, 89.9] vs 65.7 % [58.6, 73.7]; UC: 91.2 % [81.7, 100.0] vs 53.4 % [43.0, 66.2]). The main reason for CT-P13 discontinuation was loss of response (CD/UC) in both IFX-naive (14.7 %/21.7 %) and IFX-switched (7.4 %/5.1 %) groups. Among patients (CD and UC, respectively), 51.3 % and 45.2 % reported ≥1 adverse event (AE), and 13.2 % and 12.7 % reported serious AEs, respectively. ConclusionAfter two years of follow-up, the effectiveness of intravenous CT-P13 was maintained in >80 % of IFX-switched patients. CT-P13 induced effective therapeutic maintenance in IFX-naive patients. CT-P13 had an acceptable safety profile. Trial registrationClinicalTrials.gov identifier: NCT02925338