BACKGROUND: Increasing therapeutic options for inflammatory bowel disease calls for tools to aid choice of sequencing. We investigated if pharmacokinetic (PK) and pharmacodynamic (PD) failure mechanisms prompting therapy change influenced subsequent outcomes when switching to a different biologic drug class. METHODS: Retrospective single-center cohort study including patients treated first with tumor necrosis factor (TNF) inhibitors, followed by vedolizumab, and then ustekinumab. Clinical and objective disease remission were conventionally classified by validated indices. PK-PD failure was defined according to maintenance drug concentrations (PK below thresholds and PD above thresholds): infliximab 8.0 microg/mL, adalimumab 12.0 microg/mL, golimumab 1.4 microg/mL, vedolizumab 15 microg/mL. Primary treatment failure despite dose intensification was ascribed to PD. Primary endpoints were steroid-free treatment persistence and 1-year remission. RESULTS: The study included 112 patients switching from TNF inhibitors to vedolizumab (infliximab n = 61, adalimumab n = 32, golimumab n = 16, certolizumab pegol n = 3) and 31 subsequently to ustekinumab. Treatment persistence on vedolizumab did not differ between patients discontinuing TNF inhibitors due to PK (n = 28, 31%) or PD (n = 63, 69%) (mean 989 days [95% confidence interval: 554-1424] vs. 951 [659-1242], p = 0.93). One-year steroid-free clinical and objective remission rates on VDZ were also comparable between PK-PD groups (29% vs. 35%, p = 0.63 and 35% vs. 43%, p = 0.48, respectively). Findings for UST were similar. Sensitivity analyses with exclusion of primary non-responders and multivariate analyses correcting for potential confounders supported findings. CONCLUSION: PK-PD failure mechanisms do not appear to influence subsequent treatment outcomes when switching to biologics with different modes of action. Sequencing may rather rely on aspects such as efficacy, safety, and costs.