Association of early vedolizumab trough levels with clinical, biochemical, endoscopic response and drug optimization during maintenance therapy in patients with inflammatory bowel diseases.

The exposure-response relationship between vedolizumab (VDZ) trough levels (VTLs) and efficacy outcomes has been extensively studied, but data on early VTLs in Asian populations are limited. We assessed clinical outcomes and biochemical response using fecal calprotectin (BioRES[FC]) or C-reactive protein (BioRES[CRP]) at week 14 (W14) and W54, endoscopic healing (EH) at available follow-up time points, and the need for drug optimization during maintenance therapy among 67 patients treated with VDZ (39 Crohn’s disease [CD], and 28 ulcerative colitis [UC]). Associations between early VTLs and outcomes were assessed, with VTL cut-offs proposed using the area under the receiver operating curve (AUC). CD patients achieving W14 BioRES[CRP] had higher VTLs at W6 and W14. W54 BioRES[FC] responders and those not requiring drug optimization had higher W14 VTLs (11.2 vs. 3.8 µg/mL, P = 0.036; 2.2 vs. 5.8 µg/mL, P = 0.004). Proposed W14 VTL cut-offs were 5.3 µg/mL (AUC 0.859) for BioRES[FC] and 4.6 µg/mL (AUC 0.765) for drug optimization. In UC patients, higher early VTLs were noted in those achieving W14 corticosteroid-free clinical remission, W14 BioRES[FC], and W14 EH, but not consistently linked to W54 results. This real-life study suggests higher early VTLs correlated with better outcomes, with W14 VTLs potentially predicting long-term outcomes in CD patients. Future studies are needed to confirm these findings and guide VDZ therapy.