Proactive Therapeutic Drug Monitoring Is Associated With Increased Drug Persistence in Patients With Inflammatory Bowel Disease Treated With Intravenous Vedolizumab

Background: There are limited data regarding therapeutic drug monitoring (TDM) of non-anti-tumor necrosis factor therapy in inflammatory bowel disease (IBD). This study aimed to evaluate the efficacy of proactive TDM in IBD patients treated with intravenous (iv) vedolizumab (VDZ). Methods: This single-center retrospective cohort study included consecutive IBD patients treated with maintenance iv VDZ therapy undergoing TDM from November 2016 to March 2023. Patients were followed through June 2023 and were divided in to 2 groups: those who had at least 1 proactive TDM vs those who underwent only reactive TDM. A survival analysis was performed to evaluate drug persistence, defined as no need for drug discontinuation due to loss of response, serious adverse event, or an IBD-related surgery. Results: The study population consisted of 94 patients (proactive TDM, n = 72) with IBD (ulcerative colitis, n = 53). Patients undergoing at least 1 proactive TDM compared with patients having only reactive TDM demonstrated a higher cumulative probability of drug persistence (Log-rank P < .001). In multivariable Cox proportional hazard regression analysis, at least 1 proactive TDM was the only factor associated with drug persistence (hazard ratio, 14.3; 95% confidence interval [CI], 3.8-50; P < .001). A ROC analysis identified a VDZ concentration of 12.5 mu g/mL as the optimal drug concentration threshold associated with drug persistence (area under the ROC curve: 0.691; 95% CI, 0.517-0.865; P = .049). Conclusion: In this single-center retrospective study reflecting real-life clinical practice, proactive TDM was associated with increased drug persistence in patients with IBD treated with iv VDZ.