4CPS-190 Optimisation of adalimumab in children with inflammatory bowel disease: key factors for dose escalation

<h3>Background and Importance</h3> Inflammatory bowel disease (IBD) presents significant treatment challenges due to limited therapeutic options, particularly in children. Maximising the effectiveness of available treatments, like adalimumab, is crucial to improve patient outcomes. Therefore, early identification of patients most likely to adjust dosage could help optimise treatment. <h3>Aim and Objectives</h3> To describe the characteristics of IBD paediatric patients (PP) treated with adalimumab in order to identify features of those requiring dose escalation for optimisation. <h3>Material and Methods</h3> Observational, retrospective study including all IBD PP treated with adalimumab from January-2019 to July-2024. Data collected: sex, age, diagnosis, medications, adalimumab levels (AL) after induction, at 6 months, and at 1 year. Calprotectin levels and concomitant medication were evaluated at baseline, 6 months, and 1 year. Adverse drug reactions (ADRs) and reasons for discontinuation were also recorded. <h3>Results</h3> 31 patients included, 61.0% male, median age 12 years (IQR 4). 84.0% had Crohn’s disease and 16.0% ulcerative colitis. Before starting adalimumab, 71.0% were on azathioprine, 32.3% on systemic glucocorticoids, and on 16.1% mesalamine. The median AL were 11.0 (IQR 5.5) after induction, 12.1 (IQR 5.7) at 6 months, and 10.6 (IQR 8.2) at 12 months. Patients who required dose escalation had median AL of 9.4 (IQR 6.8) at 6 months and 8.3 (IQR 4.4) at 12 months, compared to 12.5 (IQR 5.2) and 13.2 (IQR 7.1) for those who did not require escalation. Calprotectin levels were classified into three groups: &gt;3000 (12.9%), 2000–3000 (29.0%), and &lt;2000 (58.1%). It was observed that 75% of patients with calprotectin &gt;3000 and 67% of those with calprotectin between 2000–3000 required dose escalation. 55% of patients on azathioprine at baseline also required dose escalation. During the study period, 58.1% of patients required dose escalation or increased dosing frequency. ADRs were reported by 23% of patients, being the most common Herpes-Zoster, respiratory infections, and skin rash (28.6% each one). 29% of patients discontinued treatment, mainly due to secondary loss of response (66.7%). <h3>Conclusion and Relevance</h3> This study suggests that higher doses of adalimumab may be necessary for IBD PP with baseline calprotectin levels &gt;2000 or those receiving concomitant azathioprine. A proactive pharmacokinetic monitoring approach of AL could optimise treatment and improve outcomes. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest