Background
Prospective data after switch from intravenous infliximab (IV-IFX) to subcutaneous (SC-IFX) in Inflammatory Bowel Disease (IBD) is needed. The aim of this prospective multicenter cohort was to describe SC-IFX persistence, efficacy and tolerance after switch from IV-IFX.
Methods
IBD patients in steroid-free clinical remission (defined by a Harvey Bradshaw index (HBI) ≤ 4 for Crohn’s disease (CD), and partial Mayo Score (PMS) ≤ 2 with no subscore >1 for ulcerative colitis UC)) for at least 6 months on IV-IFX, were enrolled in this prospective cohort if they switched to SC-IFX.
Clinical (HBI, PMS), biological (CRP, fecal calprotectin (FC)) and pharmacokinetic evaluations were performed at 3, 6, 12 and 24 months from switch. In case of clinical or biological relapse, as per physicians’ judgement, SC-IFX dose could be increased, or drug changed.
Primary endpoint was SC-IFX persistence at week 48 (W48). Secondary endpoints comprised steroid-free clinical remission at W48, proportion of patients who switched back to IV-IFX, HBI and PMS changes and FC, CRP and infliximab serum level changes. Statistical comparisons were performed using Fisher’s exact test. Survival without treatment discontinuation was analysed using a Kaplan-Meyer curve.
Results
426 patients were included (72.4% CD, 45.1% female, median age 37 years), with a median time from diagnosis of 143 months in CD, 154 months in UC. At baseline, 74% were on IV-IFX standard dose (5mg/kg every 8-week) and 68 (16%) received combination therapy with an immunosuppressant.
Among patients with complete data until W48, SC-IFX persistence was 95.3% (CI, 93.2-97.5). 319/367 (89.9%) were on steroid-free clinical remission.
From baseline to W48, median HBI and PMS scores were 0, CRP did not change significantly, median FC rate decreased significantly from 52µg/g to 36 µg/g (p=0.015). Mean Infliximab trough level at inclusion was 7.97µg/mL, while it reached 17.96µg/mL at W48 (p<0.0001).
23 (5.4%) patients had an increase of SC-IFX dose and 22 (5.2%) stopped SC-IFX, of which 6 patients switched back to IV-IFX. SC-IFX persistence was significantly higher among patients treated with SC-IFX monotherapy (98.8%) as compared to those on combination therapy (90.0%) (HR=0.14 [0.04-0.53]).
Adverse events were reported in 181/426 patients (42.4%), 12 led to treatment discontinuation. Nine severe adverse events (2%) were reported. Three patients (0.7%) had IBD-related surgery and 8 (1.9%) IBD-related hospitalization.
Conclusion
In this large multicenter prospective cohort of IBD patients in remission, one-year persistence of SC-IFX after switch from IV-IFX was 95.3%, supporting excellent efficacy and tolerance of SC-IFX.

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