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P669 Transmural healing is associated with higher infliximab trough levels in Crohn’s disease

A. Albshesh1, B. Unger1,2, S. Ben Horin2, R. Eliakim2, U. Kopylov2, D. Carter*2

1Chaim Sheba Medical Center, Gastroenterology, Tel Hashomer, Israel, 2Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv, Israel

Background

Transmural healing (TH) leads to improved long- term outcomes in Crohn’s disease. TH can be easily assessed with intestinal ultrasound (IUS). Infliximab trough levels (ITL) are associated with the likelihood of clinical response, clinical remission, mucosal healing and fistula healing in both CD and UC. However, it is unclear whether high ITL is associated with TH .

Methods

This was a retrospective chart review. CD patients treated with IFX that had available ITL during maintenance (fourth infusion and beyond) and available concurrent IUS results (within 3 months from each other) were included in the study. TH was defined as terminal ileum thickness of ≤3 mm without increased blood flow. ITL levels were measured using an in-house sandwich ELISA and compared between patients with TH and patients with non-equivocal transmural disease, defined as terminal ileum thickness >5 mm.

Results

Thirty-three CD patients (51% male, mean duration of disease-7.5 years, 91% anti-TNF-naïve) were included in the study .All patients had IUS results following the fourth (Week 14 ) infusion. TH was demonstrated in 15/33 (45%) of the patients; median ITL levels in patients with TH were significantly higher in comparison to patients with terminal ileum thickness > 5 mm (5.39, IQR 25–75% 2.5–8.9 μg/ml vs. 0.75, IQR 0.012–1 μg/ml, p = 0.011). In patients with undetectable IFX level (<1 μg/ml), median terminal ileum thickness was significantly higher than in patients with detectable ITL (4.5, IQR 3–6 mm vs. 3.2, 2.2– 4.1 mm, p = 0.034).

Conclusion

In CD patients treated with IFX, IUS-determined transmural healing is associated with higher trough Infliximab levels. As transmural healing may be associated with long-term clinical remission, it could serve as a potential target for guiding anti-TNF therapy. Our data merits validation in a larger prospective cohort.