Infliximab is approved for pediatric Crohn's disease (CD) and ulcerative colitis (UC), but is limited in children by its intravenous administration. We evaluated the effectiveness and safety of switching from intravenous to subcutaneous infliximab in pediatric patients with CD/UC.

Multicenter retrospective cohort study, from January to December 2022 in two pediatric centers, that included CD/UC patients in clinical remission and weighing ≥50kg, treated with maintenance dose IV IFX. Primary endpoint: maintenance of clinical remission at six-months post-switch; PCDAI<10 for CD, PUCAI<10 for UC. Secondary endpoints included: IFX trough levels, anti-infliximab antibodies (AIAs), adverse events, and treatment persistence.

Twenty-one patients were included: 11 (52.3%) female, median 17 years of age (range: 13-18 years), 18 (85.7%) CD and 3 (14.3%) UC. The median (range) age at diagnosis was 12 (5-15) years; at inclusion (M0; switch) it was 16 (10-18) years. All received optimized IFX regimens (10mg/kg every 8 or 4 weeks). All were in clinical remission at M0 and maintained remission throughout the 6-month follow-up. None discontinued treatment. Median (range) serum IFX trough levels was 11.3μg/mL (4.7-39μg/mL; n=13) at M0, 17.8μg/mL (8.5-20μg/mL; n=10) at M3, and 20μg/mL (17.1-20μg/mL; n=6) at M6. No patient developed AIAs. There was no serious adverse event; one patient (4.7%) experienced a mild injection site reaction.

Switching from IV to SC IFX appears effective and safe in pediatric IBD patients. Pharmacokinetic studies are required for children <50kg in order to determine the dosage of SC IFX that allows therapeutic trough values to be achieved.