4CPS-045 Long-term effectiveness and safety of proactive therapeutic drug monitoring of infliximab in paediatric inflammatory bowel disease: a real-world study

<h3>Background and Importance</h3> Therapeutic drug monitoring (TDM) strategies can be categorised as reactive or proactive. Reactive TDM is used to assess partial response and secondary loss of response, while proactive TDM guides dose individualisation to target appropriate trough serum concentrations (Cmin), potentially reducing the risk of disease relapse, treatment failure, and drug immunogenicity. <h3>Aim and Objectives</h3> To evaluate long-term effectiveness and safety of a multidisciplinary early proactive TDM programme combined with Bayesian forecasting for infliximab (IFX) dose adjustment in a real-world dataset of paediatric patients with inflammatory bowel disease (IBD). <h3>Material and Methods</h3> A descriptive, ambispective, single-centre study of paediatric patients with IBD who underwent IFX Cmin measurement between September 2015 and September 2023 was performed. Patients received reactive TDM before September 2019 (n=17) and proactive TDM thereafter (n=21). We analysed clinical, biological, and endoscopic remission, treatment failure, hospitalisations, emergency visits and adverse drug reactions. IFX doses were adjusted to maintain Cmin ≥ 5 µg/ml, with specific targets for proactive TDM based on ECCO-ESPGHAN guidelines. Statistical analyses included t-test, Wilcoxon test, χ2 test, likelihood ratio, Kaplan-Meier survival analysis, and Cox proportional hazards models. <h3>Results</h3> Of the 38 patients, 21 (55.26%) had Crohn’s disease (CD), 16 (42.11%) ulcerative colitis (UC), and 1 (2.63%) undetermined IBD. The mean (standard deviation) IFX Cmin was 6.83 (5.66) µg/ml (reactive) and 12.38 (9.24) µg/ml (proactive) (p=0.08). No statistically significant differences between groups were found in remission rates or treatment failure. The proactive group had fewer hospitalisations (14.29% vs. 23.53%) and shorter median hospitalisation days (6 vs.19), although not statistically significant. Adverse reactions were higher in the proactive group, mainly infections, but not significantly different. <h3>Conclusion and Relevance</h3> Proactive TDM showed no significant differences in treatment outcomes compared to reactive TDM. However, the results in our reactive TDM group were similar to proactive TDM results reported in other studies, which prevented us from observing significant differences. Further studies with larger samples are needed to optimise treatment strategies for paediatric IBD patients. <h3>References and/or Acknowledgements</h3> Van Rheenen PF, <i>et al</i>. The medical management of paediatric Crohn’s disease: an ECCO-ESPGHAN guideline update. <i>J Crohn’s Colitis</i>. 2021;<b>15</b>(2):171–94, https://doi.org/doi:10.1093/ecco-jcc/jjaa161 <h3>Conflict of Interest</h3> No conflict of interest