P1069 One-year clinical outcomes of switching to subcutaneous infliximab in patients with inflammatory bowel disease on maintenance of intravenous infliximab therapy with or without remission: A multicentre cohort study

Background An elective switching to the subcutaneous (SC) formulation of infliximab (IFX) has shown effectiveness and safety in patients with inflammatory bowel disease (IBD) on intravenous (IV) IFX maintenance therapy. However, data on long-term outcomes in patients not in clinical remission during maintenance therapy is limited. This study aims to evaluate the long-term outcomes of SC switching in patients who were in clinical remission and not in remission during IV IFX maintenance therapy. Methods This retrospective multicentre study was conducted from January 2021 to October 2023. Clinical remission was defined as Crohn’s Disease Activity Index (CDAI) <150 for Crohn’s disease (CD) and partial Mayo score <2 for ulcerative colitis. Biological remission was defined as faecal calprotectin (FC) <250 µg/g and C-reactive protein (CRP) <0.5 mg/dL. The primary outcome measure was 1-year treatment persistence of SC IFX. Results Among 127 patients included in the study, 80 (62.9%) had CD, and 47 (37.1%) had UC. At the time of switching, 90 patients (70.9 %) were in clinical remission; whereas, 37 (29.1 %) were in a non-remission state. The treatment persistence rate at 1 year was high at 92.9%. Treatment persistence rates between the clinical remission and non-remission groups did not differ significantly (94.4% vs. 89.2%, p=0.287). In both groups, IFX pharmacokinetics and biomarkers between baseline and 12 months (p<0.01) significantly improved. The median infliximab levels increased from a baseline of 3.3 µg/mL (interquartile range [IQR] 1.3–5.1) to 14.4 µg/mL (IQR 9.4–23.0, p<0.001) at 12 months. Disease activity index was stable in the remission group, and decreased in the non-remission group (partial Mayo score, p<0.001; CDAI, p=0.063). At the one-year follow-up, clinical remission and biological remission were achieved in 86.6% and 60.6%, respectively, an increase from baseline (70.9% and 48.0%, respectively). Biologics exposure before IFX was the only significant variable associated with treatment persistence (odds ratio 5.138, 95% confidence interval 1.150–22.951, p=0.032). The concomitant use of immunomodulators was not associated. The incidence of IFX-related adverse events was 14.2%, with only three patients discontinuing treatment. Conclusion Switching to SC IFX from IV IFX maintenance therapy demonstrated high treatment persistence and favourable safety profiles, irrespective of remission status at the time of switching. Patients in both remission or non-remission states showed significant improvement in pharmacokinetics and biomarkers, and/or stable disease activity indices.