PTH-128 Correlation of Vedolizumab trough levels with clinical and biochemical markers in inflammatory bowel disease

Introduction The clinical utility of vedolizumab (VDZ) trough levels (VTLs) is not well established. The aim of this study is to determine if there is a correlation between VTLs and clinical and biochemical outcome. Methods We performed a prospective, cross-sectional study to examine the association between VTLs and clinical and biochemical outcomes. VTLs immediately prior to VDZ infusion were collected simultaneously with CRP and Harvey Bradshaw index (HBI)/Simple Clinical Colitis Activity index (SCCAI) (for Crohn’s disease, CD, and ulcerative colitis, UC, respectively). Biochemical remission was defined as CRP ≤ 5 mg/L and clinical remission was defined as HBI ≤ 4 or SCCAI ≤ 2. Combined remission was defined as those meeting criteria for both clinical and biochemical remission. Fishers exact and Mann-Whitney U were used to compare groups and ROC analysis to identify a therapeutic threshold. Results 37 samples with matched clinical and biochemical data were collected for 36 patients (18 UC, 14 CD and 4 undifferentiated inflammatory bowel disease). An equal number of patients had 4-weekly VDZ infusions compared to 8-weekly. 21 out of 36 patients (58%) were on concomitant immunomodulation. The median trough level was 21.2 µg/mL (range Conclusions A correlation between VTLs and clinical and biochemical markers of disease activity was not able to be shown. This is a preliminary, small sample size study and analysis of VTLs for our entire VDZ cohort is being conducted at our centre.