Proactive Therapeutic Drug Monitoring of Ustekinumab Is Associated With Increased Drug Persistence in Patients With Inflammatory Bowel Disease

Background: There are limited data on the role of proactive therapeutic drug monitoring (TDM) of ustekinumab (UST) in patients with inflammatory bowel disease (IBD). This study investigated the efficacy and safety of proactive TDM in IBD patients treated with subcutaneous (sc) UST. Methods: This was a retrospective single-center cohort study. Consecutive patients with IBD who received maintenance subcutaneous (sc) UST therapy and underwent TDM from January 2017 to February 2023 were eligible for inclusion. Patients were followed through May 2024 or until drug discontinuation or an IBD-related surgery. Patients underwent either at least one proactive TDM or reactive TDM only. Survival analysis was performed to evaluate drug persistence, defined as no need for drug discontinuation due to loss of response, serious adverse event (SAE) or an IBD-related surgery, and IBD-related hospitalizations. Results: The study population consisted of 83 patients (proactive TDM, n = 46) of whom 67 (81%) had Crohn's disease. Patients who had at least one proactive TDM had higher drug persistence (Log-rank P < .001) and less IBD-related hospitalization (Log-rank P = .012) compared to patients undergoing only reactive TDM. In multivariable COX proportional hazard regression analysis, at least one proactive TDM was associated with increased drug persistence (hazard ratio [HR]: 5; 95% confidence interval [95% CI], 2-10; P < .001) and decreased IBD-related hospitalization (HR: 0.24; 95% CI, 0.07-0.83; P = .024). There was no SAE reported. Conclusions: This retrospective study showed that proactive TDM is associated with increased drug persistence and decreased IBD-related hospitalization in IBD patients treated with sc UST. Lay Summary There is still limited information regarding the role of therapeutic drug monitoring (TDM) other than antitumor necrosis factor biologics. This study showed that proactive TDM is associated with increased drug persistence and decreased inflammatory bowel disease (IBD)-related hospitalization in patients with IBD treated with ustekinumab.