Serum Ustekinumab Concentrations Are Associated With Remission in Crohn's Disease Defined by a Serum-Based Endoscopic Healing Index

Ustekinumab Drug Clearance Is Better Associated with Disease Control than Serum Trough Concentrations in a Prospective Cohort of Inflammatory Bowel Disease

Background/Objectives: This study aimed to compare the association of ustekinumab (UST) drug clearance (CL) and trough drug concentrations with disease activity in patients with inflammatory bowel diseases (IBDs). Methods: A prospective cohort of 83 patients with IBD receiving maintenance therapy with 90 mg subcutaneous UST was analyzed using Bayesian PK modeling. UST concentrations and antibodies to UST (ATU) were collected at the trough and measured using a drug-tolerant homogenous mobility shift assay (HMSA). CL was estimated using Bayesian estimation methods with priors from a previous population pharmacokinetic study specifically reparametrized using HMSA. Outcomes were combined clinical and biochemical remission and endoscopic healing index (EHI) score, a validated marker of endoscopic active disease in IBD. Statistical analysis consisted of linear and nonlinear mixed effect models for repeated time-to-event analysis. Results: A total of 83 patients with IBD were enrolled (median age 42 years, 52% female) and evaluated across 312 dose cycles (median follow-up: 279 days, median of 3 cycles/patient). Median concentrations and CL were 5.0 µg/mL and 0.157 L/day, respectively. Most patients (89%) were exposed to other biologics before starting UST, which was associated with lower rates of clinical and biochemical remission (p = 0.01). Longitudinal changes in concentrations were not associated with remission (p = 0.53). Conversely, higher CL was associated with a lower likelihood of remission (p < 0.01). EHI > 50 points (endoscopic active disease, n = 303 cycles) was associated with higher UST CL (p < 0.01). Conclusions: UST CL was more strongly associated with clinical and biochemical outcomes than trough concentrations, highlighting its potential role in therapy optimization.

Association Between Serum Ustekinumab Concentrations and Endoscopic Disease Activity in Moderate-to-Severe Crohn's Disease Patients

Background/Aims

The role of ustekinumab therapeutic drug monitoring in patients with Crohn's disease (CD) remains ambiguous. Examination of the association serum ustekinumab concentrations and endoscopic outcomes has yielded inconsistent results. Our study examined whether serum ustekinumab concentrations were associated with endoscopic healing in patients with moderate-to-severe CD.

Methods

This was a cross-sectional study of adult patients with CD on maintenance ustekinumab. Patients were included if they had serum ustekinumab concentrations and endoscopic evaluation taken within 4 months of each other. Endoscopic healing was defined as absence of ulceration on endoscopy or Simplified Endoscopic Score for Crohn's disease (SES-CD) < 3. Quartile analysis of drug levels was performed, and receiver operating characteristic curve was calculated. Multivariate logistic regression assessed for the probability of endoscopic healing based on serum ustekinumab concentration.

Results

Seventy-four patients were included in the final analysis. The mean serum ustekinumab concentration of the population was 6.10 mcg/mL. Serum ustekinumab concentration did not predict endoscopic remission based on either the absence of ulceration or SES-CD < 3. There was no difference in the frequency of ulceration at increasing serum ustekinumab concentrations. There was no threshold serum ustekinumab concentration associated with the absence of ulceration (area under the curve [AUC] = 0.50) or SES-CD < 3 (AUC = 0.49).

Conclusions

Our study found no association between serum ustekinumab concentrations and endoscopic remission in patients with CD. Exploration of mechanisms accounting for this lack of association is warranted.

Therapeutic drug monitoring in patients with inflammatory bowel disease on ustekinumab

OBJECTIVE

Therapeutic drug monitoring is used clinically to guide anti-tumor necrosis factor (TNF) therapy for inflammatory bowel disease (IBD), but its use for ustekinumab (UST) remains unclear. This study aimed to determine predictive variables of UST levels.

METHODS

In this retrospective cohort of patients with IBD, UST trough levels were drawn at maintenance dosing. Relationships between UST trough levels and demographics, therapy, and outcomes were analyzed. Machine-learning models were used to infer combinatorial traits predictive of UST levels.

RESULTS

Altogether 177 patients with IBD on UST had a mean UST trough level of 4.742 μg/mL. The injection schedule correlated significantly (P < 0.001) with UST levels. Naiveté to anti-TNFs correlated with higher UST levels (P = 0.048). Univariate analysis revealed that higher inflammatory biomarkers significantly correlated to lower UST levels and a lower Simple Endoscopic Score to Crohn's Disease to adequate UST levels (P = 0.018). Multivariate analysis identified body mass index (BMI), previous anti-TNF failure, and laboratory flare as predictors of UST levels with an area under the receiver operating characteristic curve (AUROC) of 0.72. The UST cut-off level of 5.77 μg/mL yielded a 0.79 AUROC, 80% sensitivity, and 81% specificity for predicting endoscopic remission of Crohn's disease. For the clinical remission end-point in ulcerative colitis, UST level of 4.73 μg/mL yielded a 0.69 AUROC, 53% sensitivity, and 86% specificity.

CONCLUSIONS

Higher UST levels correlated with less disease activity. BMI was an important consideration for UST response as well. Therefore, UST dose adjustments to reach target levels may optimize response.

Therapeutic Drug Monitoring for Biologic and Small-Molecule Therapies for Inflammatory Bowel Disease

Background: Inflammatory bowel disease (IBD), encompassing ulcerative colitis and Crohn's disease, necessitates long-term medical therapy to manage symptoms and prevent complications. Therapeutic drug monitoring (TDM) has emerged as a strategy to optimize treatment efficacy, particularly with anti-tumour necrosis factor (anti-TNF) alpha drugs. This review explores the role of TDM for non-anti-TNF advanced therapies in IBD, focusing on vedolizumab, ustekinumab, tofacitinib, upadacitinib, risankizumab and ozanimod. Methods: The literature search, conducted through OVID (Medline) and PubMed, delves into proactive versus reactive TDM, timing of monitoring and methods for measuring drug levels and anti-drug antibodies. Results: While ustekinumab and vedolizumab exhibit exposure-response relationships, consensus on target levels and the role of TDM adjustments remains elusive. Limited data on risankizumab suggest a dose-dependent response, while for small molecule therapies (janus kinase inhibitors and ozanimod), the absence of real-world data and commercially available TDM tools pose challenges. Conclusion: At present, with the available data, there is a limited role for TDM in non-anti-TNF biologic and small-molecule therapies. This review underscores the need for further research to delineate the utility of TDM in guiding treatment decisions for these agents.