P522 Post hoc analysis reveals limited efficacy of induction therapy in ileum only Crohn´s disease

Abstract

Abstract Background Crohn´s disease (CD) can affect any part of the GI tract, although has a predilection for the terminal ileum and colon. Approximately 30% of patients have inflammation restricted to the small intestine, another 30% have disease limited to the colon, and the remainder have a combination of small and large bowel involvement. Despite studies suggesting that ileal and colonic CD may be distinct disease phenotypes and might therefore respond differently to treatment, CD patients are typically enrolled into clinical trials irrespective of the site of gastrointestinal involvement. The aim of this systematic review and meta-analysis was to assess treatment efficacy in patients with small bowel disease. Methods Embase and PubMed databases were searched until October 2023 for randomised, placebo-controlled, clinical trials that reported induction efficacy, based on clinical remission (CDAI <150), in ileal-only Crohn’s disease between 2010 and 2023. The following search criteria were employed: Crohn´s disease AND [2010-2023] AND (small bowel OR ileum OR ileal OR L1) AND (CDAI OR clinical remission AND induction AND placebo). Additional studies, not identified through this search strategy were also considered. Resultant studies were systematically reviewed before a random-effects meta-analysis was undertaken to assess induction efficacy, based on clinical remission, in ileal only CD. Results A total of 9 studies, involving 709 adult patients, were identified: two via Embase and PubMed; six from supplementary search materials; and one post-hoc analysis of brazikumab data (not published). The studies provided CDAI remission results by disease location subset. The induction treatment times ranged from 6-12 weeks, and both bio-naïve and bio-failure patients were included. The studies were relatively homogenous (I2 = 38.5%, Q = 13.0 (p-value = 0.112)) with a random effect meta-analytic estimate of difference versus placebo in CDAI remission of 2.1% (95% CI -6% to 11%). Two studies used clinical response (defined as ≥ 100 point decrease or score < 150) as indicated in the figure. Conclusion This is the first systematic meta-analysis of treatment effects in ileal-only CD. The available evidence suggests treatment effect heterogeneity, with inferior outcomes in ileal disease versus a broader patient population with ileocolonic or colonic involvement. Previous systematic review1 on clinical remission after induction treatment demonstrate placebo adjusted values in the range of 12-20% in a no defined disease site population. This indicates the need for novel therapies with a mechanism of action directly tailored to heal the small intestine in patients with CD.