Therapeutic Drug Monitoring With Ustekinumab and Vedolizumab in Inflammatory Bowel Disease.

In patients with Crohn's disease (CD) and ulcerative colitis (UC), the use of therapeutic drug monitoring (TDM) with TNF-α antagonists has led to a personalized approach to optimize treatment and has been shown to be cost-effective. The utility of this TDM-based personalized approach for novel biologic agents, which target different inflammatory pathways, is unclear. Commercial assays for ustekinumab (UST) and vedolizumab (VDZ) are available, but there is little available guidance for clinicians regarding the use of TDM with these drugs. Although there is limited evidence for definitive threshold concentrations for UST and VDZ, this review highlights the available literature on the pharmacokinetics of these medications, the association of clinical and endoscopic outcomes with drug concentrations, and the clinical utility of TDM to guide treatment decisions.