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P450 Association of Infliximab trough levels and transmural healing in Crohn’s disease

S. Bernardo*1, S. Fernandes1, C. Simões1, A. R. Gonçalves1, C. Baldaia1, A. Valente1, P. Moura Santos1, L. Correia1, R. Marinho1

1Hospital Santa Maria, CHLN, Gastrenterology, Lisbon, Portugal

Background

As new and more effective therapies become available, more objective and rigorous therapeutic outcomes in Crohn’s disease (CD) are demanded including mucosal healing (MH) and perhaps transmural healing (TH). Several studies have shown a positive correlation between infliximab (IFX) trough levels and favourable outcomes. Nevertheless, the therapeutic range to achieve such demanding endpoints is still unknown. We aimed to assess the association between IFX trough levels and MH, magnetic resonance enterography (MRE) healing, and TH in CD.

Methods

Retrospective cohort study. Patients with CD with ileal or ileocolonic location receiving IFX treatment with an MRE, ileocolonoscopy and IFX trough level performed within a 2.8 ± 1.9-month interval were included. Active MRE was defined by a bowel wall thickening >3 mm, increased contrast enhancement, and presence of complications; MH was defined as the absence of mucosal ulceration. The presence of inactive MRE and MH defined TH. IFX trough levels were measured using a drug-sensitive assay (Theradiag®).

Results

Ninety-three patients were included; 50.5% were male with a median age of 24 (range 9–64); 83.9% of patients were under concomitant immunomodulator therapy. MH, MRE healing, and TH were present in 64.5%, 57%, and 61.3% patients, respectively. Median IFX trough levels were significantly higher in patients with MH (7.25 μg/ml (1.9–14) vs. 2.9 μg/ml (0.03–7), p = 0.034), MRE healing (7.25 μg/ml (3.75–14) vs. 2.14 μg/ml (0.03–7); p < 0.001) and TH (7.5 μg/ml (3.75–14) vs. 2.6 μg/ml (0.03–7.66), p = 0.015) with respective ROC curves for MH (0.83 (95% CI 0.682–0.978, p = 0.003), MRE healing (0.95 (95% CI 0.865–0.985, p < 0.001)) and TH (0.875 (95% CI 0.749–1.0, p < 0.001). An IFX level ≥5.2 μg/ml, ≥5.7 μg/ml and ≥5.2 μg/ml was predictive of MH (sensitivity 85%; specificity 72.7%), MRE healing (sensitivity 75.5%; specificity 90.2%) and TH (sensitivity 89.5%, specificity 75%).

Conclusion

There is a significant association between higher IFX trough levels and MH, MRE healing and TH in CD. IFX trough levels ≥ 5.2 μg/ml are required to achieve TH, suggesting that IFX levels may differ based on the treatment goal.