P384 Lower infliximab trough levels are associated with higher bowel wall thickness in Crohn’s disease

• Published in: Journal of Crohn's and colitis Vol. 14; no. Supplement_1; p. S358
• Main Authors: Frias Gomes, C, Morão, B, Neto Nascimento, C, Gouveia, C, Palmela, C, Strecht, J, Torres, J
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 15.01.2020
• ISSN: 1873-9946; 1876-4479
• DOI: 10.1093/ecco-jcc/jjz203.513

Abstract Background Therapeutic drug monitoring (TDM) is currently used to optimise anti-TNFα therapy in Crohn’s disease, as higher infliximab trough levels (ITL) are associated with better rates of clinical remission and mucosal healing. Transmural healing is emerging as a potential target in Crohn′s disease, but whether there is any relation with ITL remains unclear. Here, we investigated the relation between ITL with bowel wall thickness (BWT) in patients with CD in maintenance therapy with IFX. Methods A retrospective cohort study of CD patients treated with IFX in mono or combination therapy. Patients were included if they had an available ITL during maintenance therapy and available entero-magnetic resonance or computerised tomography performed ±4 months. Transmural inflammation was defined as BWT ≥ 4 mm. Median BWT was measured in the most affected segment. An ROC curve was plotted to determine the best cut-off point of ITL to predict transmural inflammation. Mann–Whitney U-test, logistic regression and Spearman correlation were performed to assess the ITL relation with BWT. Results Twenty-nine patients were included (males 55.2%; mean age 39.6 ± 18 years; combo therapy 48.2%). According to the Montreal Classification, most patients were A2 (75.2%), with ileal (L1: 34.5%) or ileocolic disease (L3: 51.7%), and behaviour was: B1 41.4%, B2 24.1%, and B3 34.5%, with concomitant perianal disease in 37.9%. 82.2% were in clinical remission. The median IFX TL was 3.2 μg/ml (IQR 1.15–5.15) and median bowel wall thickness was 7 mm (IQR 4–9). 75.9% of patients had BWT > 4 mm. A BWT > 4 mm was associated with lower clinical remission rates (75% vs. 100%, p = 0.27) and higher C-reactive protein (0.31 vs. 0.14, p = 0.09), albeit not significantly. The area under the curve of ITL for bowel wall thickness was 0.70 (best cut-off value 1.8). Having ITL < 1.8 μg/ml was associated with higher median BWT (8.7 vs. 5.9 mm, p = 0.02) and was a predictive factor for transmural inflammation (OR 1.57, 95% CI [1.08–2.30], p = 0.02). BWT showed a fair correlation with ITL (r = −0.43, p = 0.02). Conclusion In our cohort of CD patients treated with infliximab (mono or combo therapy), lower infliximab trough levels were associated with higher bowel wall thickness, reflecting worse transmural inflammation. Proactive TDM could offer a possibility to improve BWT and reduce transmural inflammation.