P576 Therapeutic drug monitoring as predictive marker of mucosal healing in Crohn’s disease patients treated with anti-TNF: a prospective multi-centre study

Abstract Background Anti-TNFs are currently the most commonly used drugs for Crohn’s disease (CD). Therapeutic drug monitoring (TDM) is a promising strategy to optimise the healthcare resources in case of loss of response during anti-TNF treatment, yet a proactive management of TDM is being debated. The primary aim of this prospective study was to evaluate if trough levels (TL) of adalimumab (ADL) or infliximab (IFX) could be used as a marker of therapeutic response, particularly of mucosal healing (MH). The secondary aim was to evaluate if a point-of-care (POC) assay has the same results in detecting TL as an ELISA-based test. Methods CD patients naïve to anti-TNFs who started a treatment with ADL or IFX in monotherapy in 2017 at Pisa and Genoa University Hospitals were prospectively included in this study. At Weeks 14, 22, and 54 TL were evaluated on serum samples drawn before drug administration, by using an ELISA-based test (Promonitor®, Grifols, Spain) and a POC assay (Bϋhlmann, Switzerland). At Week 54 MH (defined as the disappearance of ulcers) and clinical remission (CR) (defined as a Harvey–Bradshaw Index (HBI)