Abstract Background The aim of this study was to review infliximab induction dosing regimens for PIBD patients. Specifically, to quantify the number of patients starting on 5mg/kg dosing that needed dose and/or frequency escalation. The hypothesis was that the majority of patients starting on lower dose induction would need dose intensification. Methods A retrospective review of PIBD patients currently receiving infliximab in a single tertiary centre identified 120 eligible patients; receiving induction between 2013 and 2025. Data were collected and analysed on epidemiology, diagnosis, severity of disease, initial drug dosing and need for subsequent dose and/or frequency escalation. Post induction (pre-3rd or 4th infusion) trough infliximab levels were compared to recommended targets (15 and 5 mg/L respectively) as per ECCO-ESPGHAN guidelines.1 Results 78/120 (65%) were male and 42/120 (35%) female; with age of diagnosis between 2 and 15 years. 102/120 (85%) had Crohn’s disease, 16/120 (13%) ulcerative colitis and 2/120 (2%) had IBD-unclassified. 88/120 (73%) started on 5mg/kg induction dosing; 78/88 (89%) of these patients required either dose or frequency escalation. 58/88 (66%) needed escalation to 10mg/kg as well as escalation to 4 or 6-weekly. 13/32 (41%) patients starting on 10mg/kg needed frequency escalation. Indications for initial 10mg/kg dosing were early onset (diagnosis younger than 6 years) disease (5), fistulating (35), stricturing (3) or severe disease (8). In the 5mg/kg cohort, 9/10 (90%) early onset patients and 31/35 (89%) patients with fistulating disease needed escalation. Similarly, in the 10mg/kg cohort, 4/5 (80%) early onset patients and 6/18 (33%) patients with fistulating disease needed escalation. In the 5mg/kg cohort; 51/77 (66%) patients with available post-induction infliximab had below target levels. In the 10mg/kg cohort; 10/23 (43%) patients with available levels were below target. Conclusion Infliximab is a highly effective therapy in PIBD but adequate induction dosing is essential in attaining therapeutic drug levels and therefore early clinical remission.2 This study goes someway to support the need for dose optimisation during induction; particularly in those with early onset and/or fistulating/stricturing disease. Of note, many (41%) patients who started on higher dosing still needed further optimisation. This suggests the need for starting infliximab induction with 10mg/kg dosing (rather than 5mg/kg) with pro-active post-induction therapeutic drug monitoring. References: 1. van Rheenen PF, Aloi M, Assa A et al. The Medical Management of Paediatric Crohn’s Disease: an ECCO-ESPGHAN Guideline Update. Journal of Crohn’s and Colitis, Volume 15, Issue 2, February 2021, Pages 171–194, https://doi.org/10.1093/ecco-jcc/jjaa16 2. Kantasiripitak W, Wicha SG, Thomas D et al. A Model-Based Tool for Guiding Infliximab Induction Dosing to Maximize Long-term Deep Remission in Children with Inflammatory Bowel Diseases, Journal of Crohn’s and Colitis, Volume 17, Issue 6, June 2023, Pages 896–908, https://doi.org/10.1093/ecco-jcc/jjad009 3. Jongsma MME, Winter DA, Huynh HQ et al. Paediatric IBD Porto Group of ESPGHAN. Infliximab in young paediatric IBD patients: it is all about the dosing. Eur J Pediatr. 2020 Dec;179(12):1935-1944. doi: 10.1007/s00431-020-03750-0. Epub 2020 Aug 19. PMID: 32813123; PMCID: PMC7666662 4. Dubinsky MC, Mendiolaza ML, Phan BL et al. Dashboard-Driven Accelerated Infliximab Induction Dosing Increases Infliximab Durability and Reduces Immunogenicity, Inflammatory Bowel Diseases, Volume 28, Issue 9, September 2022, Pages 1375–1385, https://doi.org/10.1093/ibd/izab285 Conflict of interest: Dr. Morrisroe, Elizabeth: No conflict of interest Foulkes, Rebecca: No conflict of interest Lawson, Maureen: No conflict of interest Fagbemi, Andrew: No conflict of interest Chatzidaki, Virginia: No conflict of interest Lee, Chai: No conflict of interest Kala, Adnaan: No conflict of interest Rivlin, Gillian: No conflict of interest Copley, Sian: No conflicts of interest
Morrisroe et al. (Thu,) studied this question.