Vedolizumab Trough Levels and Histological Healing During Maintenance Therapy in Ulcerative Colitis

BACKGROUND AND AIMS: Histological healing may be the ultimate therapeutic goal in ulcerative colitis [UC]. We investigated, for the first time, the association between vedolizumab trough levels and histological healing in UC. METHODS: This is a single-centre retrospective cohort study including all consecutive UC patients on vedolizumab maintenance therapy who had a histological evaluation blindly to clinical data and underwent therapeutic drug monitoring, between June 2014 and March 2018. Per-event analysis was performed. Histological healing was defined as a Nancy histological index ≤1. RESULTS: Thirty-five histological samples were analysed. Median [interquartile range] vedolizumab trough levels were higher in the group with histological healing (31.5 [25-49.1] μg/mL) compared with the group without histological healing (15 [9-26.6] μg/mL, p = 0.02). The higher vedolizumab trough level quartiles tended to be associated with greater rates of histological healing [p = 0.10]. A cut-off vedolizumab trough level of 25 μg/mL predicted histological healing with an accuracy of 74% and an area under the receiver operating curve of 0.62 [95% confidence interval 0.58-0.92, p = 0.004]. Bivariate analysis identified a vedolizumab trough level ≥25 µg/mL [p = 0.006], a partial Mayo score ≤1 [p = 0.008], C-reactive protein level <5 mg/L [p = 0.005] and a Mayo endoscopic subscore ≤1 [p = 0.0004] as factors associated with histological healing. CONCLUSIONS: Histological healing was associated with higher vedolizumab trough levels during maintenance therapy in UC. A vedolizumab trough level threshold of 25 μg/mL proved most optimal to predict histological healing according to the Nancy histological index. Confirmation of these data in larger, independent cohorts is needed.