Peak Concentrations of Ustekinumab After Intravenous Induction Therapy Identify Patients With Crohn's Disease Likely to Achieve Endoscopic and Biochemical Remission

External Evaluation of Population Pharmacokinetic Models of Ustekinumab in Patients with Inflammatory Bowel Disease

BACKGROUND

Population pharmacokinetic (popPK) models are essential tools for optimizing ustekinumab (UST) dosing for the treatment of inflammatory bowel disease (IBD) through therapeutic drug monitoring. The external validation of these models is necessary to ensure their predictive performance and clinical utility. The aim of the study was to externally validate 4 published popPK models of UST in a real-world cohort of patients with IBD using prediction-based and simulation-based diagnostics, as well as Bayesian forecasting.

METHODS

Four popPK models of UST, identified through a systematic literature review, were evaluated using data from 99 patients with IBD and 374 serum UST concentrations. Predictive performance and Bayesian forecasting were assessed using statistical metrics, including mean prediction error, median prediction error (MDPE), and median absolute prediction error (MADPE). The acceptability criteria (MDPE ±20%, MADPE ≤30%, F20 ≥35%, and F30 ≥50%) were applied.

RESULTS

None of the models satisfied the predefined acceptability criteria. The Xu et al model demonstrated the best performance, achieving an MDPE of 19.55% and the lowest RMSPE (2.88 mcg/mL), but F20 (20.1%) and F30 (32.4%) values fell below thresholds. The model proposed by Adedokun et al showed strong results in simulation-based diagnostics, with only 5.6% of the observed concentrations outside the prediction interval.

CONCLUSIONS

The models developed by Xu et al and Adedokun et al exhibited the most promising predictive performance and potential clinical applicability for model-informed precision dosing. Refinements to these models and further research are required to enhance their use in personalized UST therapies for IBD.

Body weight-range based initial dosing of ustekinumab in Crohn's disease: Is it an ideal approach?

BACKGROUND & AIMS

The initial intravenous dose of ustekinumab (UST) for treating Crohn's disease (CD) is recommended based on body weight ranges for clinical convenience. However, patients whose body weight nears the upper threshold may receive a relatively lower dose (<6 mg/kg) based on current dosage calculations. We aimed to investigate whether the body weight-range based dosing calculation method for UST may lead to suboptimal therapeutic doses and then impact effectiveness, particularly in patients with borderline weight.

METHODS

A multi-center, observational, real-world cohort study was conducted in four centers. Patients with CD who received UST based on body weight-range dosing calculation were retrospectively enrolled. Participants were classified into two groups according to the initial induction dosage: the relatively higher dose (RHD) induction group (≥6 mg/kg) and the relatively lower dose (RLD) induction group (<6 mg/kg). Steroid-free remission, clinical remission, specific objective response and remission at week 24 were compared in the two groups using propensity score weighting. UST drug concentration was measured at week 24±4.

RESULTS

A total of 438 patients were included, with 176 patients in the RHD group and 262 patients in the RLD group. The RHD group demonstrated superior outcomes compared to the RLD group in achieving steroid-free remission (66.2 % vs. 54.9 %, P = 0.020, OR = 1.605, 95 % CI 1.082-2.395), clinical remission (66.7 % vs. 56.4 %, P = 0.032, OR = 1.546, 95 % CI 1.041-2.311) at week 24. In objective evaluation, the RHD group showed higher rates in ultrasound response (64.9 % vs. 52.1 %, P = 0.041, OR = 1.700, 95 % CI 1.027-2.844) and radiologic remission (25.1 % vs. 13.4 %, P = 0.022, OR = 2.163, 95 % CI 1.117-4.205). The drug concentration was significantly higher in the RHD group compared to the RLD group at week 24 [2.06 (1.36-3.17) µg/ml vs. 1.12 (0.25-1.52) µg/ml, P < 0.001]. Additionally, the RHD group required fewer treatment optimizations than the RLD group, but with no statistical difference (20.6 % vs. 24.9 %, P = 0.291, OR = 0.780, 95 % CI 0.488-1.231). The rate of adverse events was similar between the two groups (4.0 % vs 3.4 %, P = 0.767).

CONCLUSIONS

This study suggested that the current dose calculation method may result in inadequate induction doses of UST for CD patients whose body weight is close to the upper threshold, potentially impacting the effectiveness of induction.

LAY SUMMARY

A multi-center study suggests that the current body weight-range based dosing of ustekinumab for Crohn's disease may lead to insufficient induction doses for patients near the upper weight threshold, negatively impacting treatment effectiveness.

Model-informed precision dosing: State of the art and future perspectives

Model-informed precision dosing (MIPD) stands as a significant development in personalized medicine to tailor drug dosing to individual patient characteristics. MIPD moves beyond traditional therapeutic drug monitoring (TDM) by integrating mathematical predictions of dosing and considering patient-specific factors (patient characteristics, drug measurements) as well as different sources of variability. For this purpose, rigorous model qualification is required for the application of MIPD in patients. This review delves into new methods in model selection and validation, also highlighting the role of machine learning in improving MIPD, the utilization of biosensors for real-time monitoring, as well as the potential of models integrating biomarkers for efficacy or toxicity for precision dosing. The clinical evidence of TDM and MIPD is discussed for various medical fields including infection medicine, oncology, transplant medicine, and inflammatory bowel diseases, thereby underscoring the role of pharmacokinetics/pharmacodynamics and specific biomarkers. Further research, particularly randomized clinical trials, is warranted to corroborate the value of MIPD in enhancing patient outcomes and advancing personalized medicine.

Comparative evaluation of point of care assay with ELISA techniques for quantifying serum concentrations of ustekinumab in inflammatory bowel disease patients

OBJECTIVES

To evaluate the analytical performance and clinical utility of the POC-AFIAS assay in comparison with two ELISA established assays for quantifying serum concentrations of ustekinumab.

METHODS

A prospective study was conducted. Consecutive serum samples from adult patients undergoing treatment with ustekinumab were collected. Three analytical techniques were compared for the quantification of ustekinumab serum concentrations: the AFIAS-10® POC assay (POC-AFIAS), the Promonitor® ELISA assay (ELISA-PRO), and the ELISA Ridascreen® assay (ELISA-RDSC). Ustekinumab concentrations were evaluated within three therapeutic ranges: <1μg/mL, 1-4.5μg/mL, and >4.5μg/mL. Statistical analysis included Pearson correlation, intra-class correlation coefficient, and Bland-Altman analysis.

RESULTS

A total of 104 patients were included in the study. The median ustekinumab concentrations measured were 5.22μg/mL (POC-AFIAS), 3.99μg/mL (ELISA-PRO), and 4.50μg/mL (ELISA-RDSC). Strong correlations were observed between techniques (POC-AFIAS and ELISA-PRO: r=0.921, POC-AFIAS and ELISA-RDSC: r=0.940, ELISA-PRO and ELISA-RDSC: r=0.976). The Bland-Altman analysis revealed a bias difference of 1.81μg/mL between POC-AFIAS and ELISA-PRO, and 1.27μg/mL between POC-AFIAS and ELISA-RDSC. Agreement rates varied by therapeutic range, with the highest agreement observed within the therapeutic range (97.3%) and lower agreement for supra-therapeutic concentrations (74.6%).

CONCLUSION

This study demonstrated that the POC-AFIAS assay provides comparable results to established ELISA techniques for quantifying serum concentrations of ustekinumab, particularly within the therapeutic range. The findings suggest that the POC-AFIAS assay offers a rapid and effective tool for managing ustekinumab therapy in clinical practice.

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.

High-throughput, low-cost quantification of 11 therapeutic antibodies using caprylic acid precipitation and LC-MS/MS

BACKGROUND

Therapeutic drug monitoring of treatment with therapeutic antibodies is hampered by the application of a wide range of different methods in the quantification of serum levels. LC-MS based methods could significantly improve comparability of results from different laboratories, but such methods are often considered complicated and costly. We developed a method for LC-MS/MS based quantification of 11 therapeutic antibodies concomitantly measured in a single run, with emphasis on simplicity in sample preparation and low cost.

RESULTS

After a single-step sample purification using caprylic acid precipitation to remove interfering proteins, the sample underwent proteolysis followed by LC-MS/MS analysis. Infliximab is used as internal standard for sample preparation while isotope-labeled signature peptides identified for each analyte are internal standards for the LC-MS/MS normalization. The method was validated according to recognized guidelines, and pipetting steps can be performed by automated liquid handling systems. The total precision of the method ranged between 2.7 and 7.3 % (5.1 % average) across the quantification range of 4-256 μg/ml for all 11 drugs, with an average accuracy of 96.3 %. Matrix effects were xamined in 55 individual patient samples instead of the recommended 6, and 147 individual patient samples were screened for interfering compounds.

SIGNIFICANCE AND NOVELTY

Our method for simultaneous quantification of 11 t-mAb in human serum allows an unprecedented integration of robustness, speed and reduced complexity, which could pave the way for uniform use in research projects and clinical settings alike. In addition, the first LC-MS protocol for signature peptide-based quantification of durvalumab is described. This high throughput method can be readily adapted to a drug panel of choice.

Therapeutic drug monitoring in inflammatory bowel diseases. Position statement of the Spanish Working Group on Crohn's Disease and Ulcerative Colitis

The treatment of inflammatory bowel disease has undergone a significant transformation following the introduction of biologic drugs. Thanks to these drugs, treatment goals have evolved from clinical response and remission to more ambitious objectives, such as endoscopic or radiologic remission. However, even though biologics are highly effective, a significant percentage of patients will not achieve an initial response or may lose it over time. We know that there is a direct relationship between the trough concentrations of the biologic and its therapeutic efficacy, with more demanding therapeutic goals requiring higher drug levels, and inadequate exposure being common. Therapeutic drug monitoring of biologic medications, along with pharmacokinetic models, provides us with the possibility of offering a personalized approach to treatment for patients with IBD. Over the past few years, relevant information has accumulated regarding its utility during or after induction, as well as in the maintenance of biologic treatment, in reactive or proactive strategies, and prior to withdrawal or treatment de-escalation. The aim of this document is to establish recommendations regarding the utility of therapeutic drug monitoring of biologics in patients with inflammatory bowel disease, in different clinical practice scenarios, and to identify areas where its utility is evident, promising, or controversial.

Systematic Review and Meta-analysis: The Association Between Serum Ustekinumab Trough Concentrations and Treatment Response in Inflammatory Bowel Disease

BACKGROUND

Optimizing therapy and monitoring response are integral aspects of inflammatory bowel disease treatment. We conducted a systematic review and meta-analysis to determine whether serum ustekinumab trough concentrations during maintenance therapy were associated with ustekinumab treatment response in patients with inflammatory bowel disease.

METHODS

A systematic review was performed to March 21, 2022, to identify studies using MEDLINE, EMBASE, and the Cochrane library. We included studies that reported the association between serum ustekinumab trough concentrations with clinical or endoscopic remission. Outcome measures were combined across studies using the random-effects model with an odds ratio (OR) for binary outcomes of endoscopic and clinical remission.

RESULTS

We identified 14 observational studies that were included in the analysis for clinical remission (919 patients, 63% with Crohn's disease) or endoscopic remission (290 patients, all with Crohn's disease). Median ustekinumab trough concentrations were higher amongst individuals achieving clinical remission compared with those not achieving remission (mean difference, 1.6 ug/mL; 95% confidence interval [CI], 0.21-3.01 ug/mL). Furthermore, individuals with median serum trough concentration in the fourth quartile were significantly more likely to achieve clinical (OR, 3.61; 95% CI, 2.11-6.20) but not endoscopic remission (OR, 4.67; 95% CI, 0.86-25.19) compared with those with first quartile median trough concentrations.

CONCLUSION

Based on the results of this meta-analysis primarily relating to patients with Crohn's disease on maintenance ustekinumab treatment, it appears that there is an association between higher ustekinumab trough concentration and clinical outcomes. Prospective studies are required to determine whether proactive dose adjustments of ustekinumab therapy provides additional clinical benefit.

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.

The Future of Advanced Therapies for Pediatric Crohn's Disease

Pediatric Crohn's disease commonly presents with moderate-to-severe intestinal inflammation with a greater risk of complications if remission is not achieved. Anti-tumor necrosis factor therapies have offered the possibility of deep and durable remission; however, many children do not respond or no longer respond over time. Further, some children do not require broader systemic immunosuppression to achieve remission and are better served by an alternative treatment strategy. Proper utilization of advanced biologic and small-molecule therapies, which have become available for adult patients since anti-tumor necrosis factor medications, is paramount for tighter disease control for a large proportion of children. Newer advanced therapies such as anti-integrin and anti-interleukin biologics, and several small-molecule agents capitalize on various mechanisms through narrower immunologic targets and reduced immunogenicity. Given limited regulatory approvals of these agents for use in children with Crohn's disease, clinicians continue to rely on data extrapolated from clinical trials in adult patients, sparse pediatric studies, and a growing real-world experience for treatment selection and optimization. In this article, we discuss currently available treatment options, pipeline drugs, and relevant data as they pertain to some of the most pressing clinical challenges faced in treating pediatric Crohn's disease.

Evaluation of serum cytokines and acute phase proteins as possible pharmacodynamic biomarkers to monitor endoscopic remission during ustekinumab therapy in patients with Crohn's disease

Background

Since not all Crohn's disease (CD) patients respond adequately to ustekinumab therapy, biomarkers could aid to monitor treatment response and optimize therapeutic outcomes.

Objectives

To explore the dynamics of serum biomarker concentrations to monitor the response to ustekinumab treatment in CD patients.

Design

Retrospective, exploratory study to evaluate concentrations of serum cytokines and acute phase proteins and their relation to endoscopic remission in CD patients during ustekinumab treatment.

Methods

Serum concentrations of 16 proteins including cytokines and acute phase proteins were measured using the Mesoscale Discovery Platform in serum of healthy controls (n = 13), and CD patients (n = 61) at baseline (week 0), week 8 and week 24 during ustekinumab treatment. Endoscopic remission was defined as simple endoscopic score for CD (SES-CD) <3 after 6 months of therapy.

Results

Absolute concentrations of serum amyloid A protein (SAA; week 8), IL-6 (week 24), AGP (weeks 8 and 24), interferon (IFN)-γ (weeks 8 and 24), lipopolysaccharide binding protein (LBP; weeks 8 and 24) and IL-22 (weeks 8 and 24) were significantly lower in endoscopic remitters compared to non-responders (p-values ranging between <0.001 and <0.05). SAA (week 8) and AGP (week 24) were the biomarkers with the highest area under the ROC curve (AUROC; 0.761 and 0.760, respectively) for identifying patients in endoscopic remission, though their performance was not superior to C-reactive protein (CRP) or faecal calprotectin. AUROCs of the predictive probability of biomarker combinations showed superiority in discriminating endoscopic remitters from non-responders in comparison to single biomarker measurements, but not as compared to faecal calprotectin.

Conclusion

Although not superior to faecal calprotectin, measurement of AGP, SAA, LBF, IFN-γ, IL-6 and IL-22 concentrations, and combinations thereof with or without CRP and faecal calprotectin, during ustekinumab therapy might contribute to adequate monitoring of treatment response in CD patients.

IL-12 and IL-23 pathway inhibition in inflammatory bowel disease

Interleukin-12 (IL-12) and interleukin-23 (IL-23), which belong to the IL-12 family of cytokines, have a key role in intestinal homeostasis and inflammation and are implicated in the pathogenesis of inflammatory bowel disease. Upon their secretion by antigen-presenting cells, they exert both pro-inflammatory and anti-inflammatory receptor-mediated effects. An increased understanding of these biological effects, particularly the pro-inflammatory effects mediated by IL-12 and IL-23, has led to the development of monoclonal antibodies that target a subunit common to IL-12 and IL-23 (p40; targeted by ustekinumab and briakinumab), or the IL-23-specific subunit (p19; targeted by risankizumab, guselkumab, brazikumab and mirikizumab). This Review provides a summary of the biology of the IL-12 family cytokines IL-12 and IL-23, discusses the role of these cytokines in intestinal homeostasis and inflammation, and highlights IL-12- and IL-23-directed drug development for the treatment of Crohn's disease and ulcerative colitis.

Predictive factors of the clinical efficacy of ustekinumab in patients with refractory Crohn's disease: tertiary centers experience in Japan

PURPOSE

Therapeutic efficacy of ustekinumab in the real-world data is limited in patients with refractory Crohn's disease (CD). In addition, factors predictive of better therapeutic efficacy of ustekinumab remains unsolved in CD. We aimed to evaluate therapeutic efficacy of ustekinumab in patients with refractory CD and to identify the factors associated with the efficacy of ustekinumab.

METHODS

We retrospectively analyzed the clinical data of 72 patients treated with ustekinumab for refractory CD. Therapeutic efficacy was assessed at weeks 8, 26, 52, and 104 on the basis of dual remission, defined as the combination of Crohn's Disease Activity Index < 150 and CRP < 0.3 mg/dL, and factors predictive of the induction and maintenance of dual remission were investigated. The cumulative continuation rates and safety of ustekinumab were assessed.

RESULTS

The dual remission rates at weeks 8, 26, 52, and 104 were 31.9%, 37.9%, 47.5%, and 42.6%, respectively. A short disease duration (≤ 2 years) and higher baseline serum albumin levels (≥ 3.1 g/dL) were positively associated with dual remission at weeks 8 and 52. Meanwhile, higher serum CRP levels (≥ 1.19 mg/dL) were negatively associated with dual remission at week 8. The cumulative ustekinumab continuation rate was favorable, and no severe adverse events were found.

CONCLUSION

A short disease duration and higher baseline serum albumin levels might be predictive of favorable therapeutic efficacy of ustekinumab in refractory CD. Induction efficacy appears to be lower in patients with higher serum CRP levels.

Systematic Review and Meta-Analysis of Observational Studies on the Effectiveness and Safety of Ustekinumab among Patients with Inflammatory Bowel Disease in Eastern and Western Countries

BACKGROUND

Ustekinumab (UST) is an IL12/23 inhibitor utilized for altering inflammatory responses in inflammatory bowel disease (IBD). Clinical trials and case reports suggested that the effectiveness and safety of UST may differ among IBD patients in Eastern and Western countries. However, related data have not been systematically reviewed and analyzed.

METHODS

This systematic review and meta-analysis of the safety and effectiveness of UST in IBD included relevant literature from the Medline and Embase databases. The main outcomes were clinical response, clinical remission, endoscopic response, endoscopic remission, and adverse events in IBD.

RESULTS

We analyzed 49 real-world studies, most of which included patients with biological failure (89.1% CD and 97.1% UC). In UC patients, clinical remission rates were 34% at 12 weeks, 40% at 24 weeks, and 37% at 1 year. In CD patients, clinical remission rates were 46% at 12 weeks, 51% at 24 weeks, and 47% at 1 year. Clinical remission rates of CD patients were 40% at 12 weeks and 44% at 24 weeks in Western countries, versus 63% and 72% in Eastern countries, respectively.

CONCLUSION

UST is an effective drug for IBD with a promising safety profile. Although no RCTs have been performed in Eastern countries, the effectiveness of UST on CD patients is not inferior to that in Western countries based on the existing data.

Ustekinumab Tissue and Serum Levels in Patients With Crohn's Disease Are Closely Correlated Though Not Consistently Associated With Objective Response After Induction

BACKGROUND

Ustekinumab (UST), which targets p40/interleukin (IL)-23 and IL-12, is an effective treatment for Crohn's disease (CD). Therapeutic drug monitoring may optimize UST posology. The aim of this study was to investigate UST and IL-23 serum and tissue concentrations in relation to mucosal inflammation and treatment response at an early time point.

METHODS

CD patients starting UST between December 2016 and November 2018 were prospectively enrolled. Endoscopies were performed at baseline and week 16. UST and IL-23 serum and tissue concentrations were measured at week 16. Clinical and biochemical response were defined as decline of ≥3 points in Harvey-Bradshaw Index and reduction of ≥50% in fecal calprotectin levels. Endoscopic response was defined as a ≥50% decline in Simple Endoscopic Score or a decline of ≥1 points in Rutgeerts score. Histological remission was defined as Global Histologic Disease Activity Score ≤4.

RESULTS

Of 56 included patients, 17 (30%) of 56 showed clinical response, 16 (30%) of 53 showed biochemical response, and 20 (36%) of 56 showed endoscopic response. UST, but not IL-23, concentration in biopsies was correlated to levels in corresponding sera (P < .0001). No correlation was found between UST tissue levels and treatment response. Patients achieving biochemical response showed significantly higher UST serum levels (3.12 µg/mL vs 1.41 µg/mL; P = .01). Tissue IL-23-to-UST ratio correlated with mucosal inflammation (P = .01).

CONCLUSIONS

This is the first study to demonstrate a correlation between serum and tissue UST levels. While tissue IL-23-to-UST ratio correlated with mucosal inflammation, UST serum levels were more indicative for biochemical response. The role of UST levels for therapeutic drug monitoring in inflammatory bowel disease needs further research.

Comparison of Ustekinumab Trough Concentrations Measured by 2 ELISA Kits and Evaluation of Clinical Response in Crohn's Disease

BACKGROUND

Ustekinumab is a recently introduced biological agent for the treatment of Crohn's disease. The clinical use of the trough concentration of ustekinumab is not as standardized as that of infliximab. The authors aimed to introduce a measurement method and the results of trough concentrations of ustekinumab in clinical applications.

METHODS

Thirty-two blood samples from 10 young adult patients diagnosed with Crohn's disease were analyzed. During the maintenance treatment, injection intervals were shortened from 12 weeks to 8 weeks in 4 patients who exhibited a loss of response. Ustekinumab trough concentrations were measured using 2 commercial ELISA kits, kit A and kit B.

RESULTS

The median trough concentrations measured with kits A and B were 0.26 and 0.38 mcg/mL, respectively. In the case of kit A, low trough concentrations were undetected on many occasions and measured as zero, whereas kit B displayed their relative values even at low concentrations. Poor clinical parameters, elevated erythrocyte sedimentation rate, C-reactive protein, and calprotectin levels were significantly correlated with lower trough concentrations ( P < 0.05). The area under the receiver operating characteristics curve of kit B (0.921) was greater than that of kit A (0.744). The optimal cutoff values for prediction clinical responses were 0.17 and 0.41 mcg/mL for kit A and kit B, respectively.

CONCLUSIONS

The trough concentration of ustekinumab measured by the 2 ELISA kits correlated with laboratory results that indicated the activity of Crohn's disease. Furthermore, kit B detected even minute changes in trough concentrations.

Optimizing Therapies Using Therapeutic Drug Monitoring: Current Strategies and Future Perspectives

Therapeutic drug monitoring (TDM) has emerged as a strategy for treatment optimization in inflammatory bowel diseases to maximize benefit and to reach more stringent, objective end points. Optimal drug concentrations in inflammatory bowel disease vary according to treatment target, disease phenotype, inflammatory burden, and timing of sampling during the treatment cycle. This review provides an update on TDM with biologic and oral small molecules, evaluates the role of reactive vs proactive TDM, and identifies the gaps in current evidence. In the future, adaptations to how we use TDM may contribute further to the goal of personalized treatment in patients with IBD.

Therapeutic drug monitoring of biologics in inflammatory bowel disease: unmet needs and future perspectives

Therapeutic drug monitoring (TDM) has emerged as a useful tool for optimising the use of biologics, and in particular anti-tumour necrosis factor (anti-TNF) therapy, in inflammatory bowel disease (IBD). However, challenges remain and are hindering the widespread implementation of TDM in clinical practice. These barriers include identification of the optimal drug concentration to target, the lag time between sampling and results, and the proper interpretation of anti-drug antibody titres among different assays. Solutions to overcome these barriers include the harmonisation of TDM assays and the use of point-of-care testing. Other unmet needs include well designed prospective studies and randomised controlled trials focusing on proactive TDM, particularly during induction therapy. Future studies should also investigate the utility of TDM for biologics other than anti-TNF therapies in both IBD and other immune-mediated inflammatory diseases such as rheumatoid arthritis and psoriasis, and the use of pharmacokinetic modelling dashboards and pharmacogenetics towards individual personalised medicine.

Ustekinumab concentrations shortly after escalation to monthly dosing may identify endoscopic remission in refractory Crohn's disease

OBJECTIVES

Some patients with Crohn's disease do not achieve remission with the approved maintenance dosing of ustekinumab every 8 weeks, possibly due to insufficient drug exposure. We aimed to study the exposure-response relationship for endoscopic remission and biomarker normalization with ustekinumab dose escalation to every 4 weeks.

METHODS

Out of 135 consecutive patients, 44 with active Crohn's disease despite standard maintenance dosing [at least one of C-reactive protein (CRP) >5 mg/L, fecal calprotectin >100 mg/kg, simple endoscopic score (SES) for Crohn's disease >3] underwent dose escalation to every 4 weeks. Subsequent endoscopic remission (SES-CD ≤3 without ulceration) and biomarker normalization were compared against ustekinumab concentrations.

RESULTS

Dose escalation led to endoscopic remission in 28.6% (8/28), CRP normalization 29.2% (7/24) and fecal calprotectin normalization 51.7% (15/29) of patients. Ustekinumab concentrations after escalation were higher in patients with endoscopic remission (6.90 vs. 4.29 mg/L; P = 0.025) and fecal calprotectin normalization (6.65 vs. 3.74 mg/L; P = 0.001). A threshold of 6.00 mg/L identified endoscopic remission [area under the receiver operating curve (AUROC): 0.775; 95% confidence interval (CI), 0.551-0.999), a threshold of 4.40 mg/L (AUROC 0.755; 95% CI, 0.545-0.964) two months after escalation identified patients with fecal calprotectin normalization at the end of follow-up. Concentrations <3.5 mg/L after escalation precluded endoscopic remission or biomarker normalization.

CONCLUSION

Endoscopic remission was associated with higher ustekinumab concentrations after dose escalation. Patients with concentrations <3.5 mg/L after dose escalation are unlikely to achieve endoscopic remission or biomarker normalization.

Ustekinumab induction concentrations are associated with clinical and biochemical outcomes at week 12 of treatment in Crohn's disease

BACKGROUND

We investigated relationships between induction ustekinumab levels and clinical and biochemical outcomes in Crohn's disease.

METHODS

Following standard IV induction, ustekinumab levels were measured at week 2 (wk2) and week 6 (wk6). Ustekinumab levels were compared in patients receiving 260, 390 and 520 mg at induction. Crohn's disease activity index (CDAI), serum albumin, C-reactive protein (CRP) and fecal calprotectin (FCP) were measured at baseline and week 12 (wk12). Associations between ustekinumab levels and these parameters were assessed. Ustekinumab levels were compared between patients requiring dose intensification within one year of induction and those remaining on standard dosing.

RESULTS

Of 23 wk2 ustekinumab levels, 22(95.7%) were above the upper limit of quantification of the assay (25 µg/mL). Median wk6 ustekinumab level (n = 25) was 14.2 μg/mL [interquartile range (IQR), 9.6-20.1]. Median wk6 ustekinumab levels in patients receiving 260, 390 and 520 mg were 8.6, 16.3 and 25.0 µg/mL, respectively, P = 0.01. There were significant correlations between baseline albumin and wk6 ustekinumab levels; r = 0.644 [95% confidence interval (CI), 0.304-0.839], P < 0.001, and between baseline FCP and wk6 ustekinumab levels; r = -0.678 (95% CI, -0.873 to -0.296), P < 00.01. Median wk12 CDAI (n = 18), CRP (n = 22) and FCP (n = 13) were 78 (IQR, 52.5-152), 1.75 mg/L (IQR, 0.93-7.03) and 746 μg/g (IQR, 259-2100), respectively. There were significant correlations between wk6 ustekinumab levels and wk12 CDAI; r = -0.513 (95% CI, -0.796 to -0.046), P = 0.03; and between wk6 ustekinumab levels and wk12 CRP; r = -0.578 (95% CI, -0.808 to -0.194), P < 0.01. Wk6 ustekinumab levels were lower in patients undergoing subsequent dose intensification; 12.5 vs. 19.6 µg/mL, P = 0.04.

CONCLUSION

Wk6 ustekinumab levels are significantly associated with baseline Crohn's disease biomarkers and subsequent clinical and biochemical outcomes.

Ustekinumab trough concentration affects clinical and endoscopic outcomes in patients with refractory Crohn's disease: a Chinese real-world study

BACKGROUND

Ustekinumab (UST), a newly-used biologic targeting p40 subunit of IL12 and IL23 in China, exerts a confirmed therapeutic effect on the induction and maintenance therapies for refractory Crohn's disease (CD). Therapeutic drug monitoring based on trough and antibody concentration is of core importance when treating patients who lose response to UST. We aimed to analyze the UST exposure-response relationship in CD treatment in the real-world setting.

METHODS

We retrospectively enrolled patients with CD who received UST between March 1, 2020 and May 31, 2021, at the inflammatory bowel disease (IBD) center of the Sun Yat-Sun Affiliated Sixth Hospital. Baseline characteristic information, biomarker examination, clinical outcomes determined by the Crohn's disease activity index (CDAI), and endoscopic outcomes evaluated using a simple endoscopic score for Crohn's disease (SES-CD) at week 16/20 were collected. The optimal UST cut-off trough concentration was identified using receiver operating characteristic curve (ROC) analysis.

RESULTS

Nineteen eligible patients were included in the study, the mean age was 29.1 ± 9.1 years and the mean disease duration was 5.5 ± 4.7 years. At the initiation of the study, 89.5% of the patients had been exposed to prior biologics, 42.1% had previous CD-related surgeries, and 52.6% had perianal diseases. At week 16/20 after the UST initiation, clinical response, clinical remission, endoscopic response, and endoscopic remission were 89.5%, 84.2%, 42.2%, and 73.7%, respectively. The cut-off optimal trough concentration for UST was 1.12 μg/mL, as determined by the ROC with an area under the curve (AUC) of 0.78, sensitivity of 87.5%, and specificity of 72.7%. Patients with a UST trough concentration > 1.12 μg/mL had a significantly higher rate of endoscopic remission than those without (70.0% vs. 11.1%, P = 0.02).

CONCLUSIONS

UST is an effective therapeutic option for refractory CD treatment. A UST trough concentration above 1.12 μg/mL was associated with endoscopic remission at week 16/20 after UST initiation. Trial registration This study was approved and retrospectively registered by the Ethics Committee of Sun Yat-Sen University (2021ZSLYEC-066, March 29, 2021) and the Clinical Trial Registry (NCT04923100, June 10, 2021).

A Comprehensive Literature Review and Expert Consensus Statement on Therapeutic Drug Monitoring of Biologics in Inflammatory Bowel Disease

Therapeutic drug monitoring (TDM) of biologics is a rapidly evolving field. We aimed to provide a consensus statement regarding the clinical utility of TDM for biologics in inflammatory bowel disease (IBD). A modified Delphi method was applied to develop consensus statements. A comprehensive literature review was performed regarding TDM of biologic therapies in IBD, and 45 statements were subsequently formulated on the potential application of TDM in IBD. The statements, along with literature, were then presented to a panel of 10 gastroenterologists with expertise in IBD and TDM who anonymously rated them on a scale of 1-10 (1 = strongly disagree and 10 = strongly agree). An expert consensus development meeting was held virtually to review, discuss, refine, and reformulate statements that did not meet criteria for agreement or that were ambiguous. During the meeting, additional statements were proposed. Panelists then confidentially revoted, and statements rated ≥7 by 80% or more of the participants were accepted. During the virtual meeting, 8 statements were reworded, 7 new statements were proposed, and 19 statements were rerated. Consensus was finally reached in 48/49 statements. The panel agreed that reactive TDM should be used for all biologics for both primary nonresponse and secondary loss of response. It was recommended that treatment discontinuation should not be considered for infliximab or adalimumab until a drug concentration of at least 10-15 μg/mL was achieved. Consensus was also achieved regarding the utility of proactive TDM for anti-tumor necrosis factor therapy. It was recommended to perform proactive TDM after induction and at least once during maintenance. Consensus was achieved in most cases regarding the utility of TDM of biologics in IBD, specifically for reactive and proactive TDM of anti-tumor necrosis factors.

Ustekinumab Dosing Individualization in Crohn's Disease Guided by a Population Pharmacokinetic-Pharmacodynamic Model

Ustekinumab is a monoclonal antibody used in Crohn’s disease (CD). Dose optimization in case of non-response and the role of pharmacokinetic–pharmacodynamic (PK-PD) monitoring remain unresolved dilemmas in clinical practice. We aimed to develop a population PK-PD model for ustekinumab in CD and simulate efficacy of alternative dosing regimens. We included 57 patients and recorded their characteristics during 32 weeks after starting with ustekinumab therapy. Serum ustekinumab concentration was prospectively measured and fecal calprotectin (FC) concentration was used to monitor the disease activity. Ustekinumab PK-PD was described by a two-compartment target-mediated drug disposition model linked to an indirect response model. Lower fat-free mass, higher serum albumin, previous non-exposure to biologics, FCGR3A-158 V/V variant and lower C-reactive protein were associated with higher ustekinumab exposure. Model-based simulation suggested that 41.9% of patients receiving standard dosing achieve biochemical remission at week 32. In patients not achieving remission with standard dosing at week 16, transition to 4-weekly subcutaneous maintenance dosing with or without intravenous reinduction resulted in comparably higher remission rates at week 32 (51.1% vs. 49.2%, respectively). Our findings could be used to guide stratified ustekinumab treatment in CD, particularly in patients with unfavorable characteristics, who might benefit from early transition to 4-weekly maintenance dosing.

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

Background

Optimal ustekinumab levels (UST) in Crohn disease (CD) treatment have not been defined. We set out to define the optimal UST to differentiate between remission and active CD, as defined using the serum-based endoscopic healing index (EHI).

Methods

Paired serum UST and EHI tests were analyzed. Remission was defined as EHI <20. Active disease was defined as EHI ≥50. The proportion of patients in remission was compared across UST quartiles. UST in subjects with EHI <20 and EHI ≥50 were compared. An area under receiver operating characteristic curve was generated to identify an optimal UST to differentiate between active disease and remission.

Results

A total of 337 unique patients were identified; median UST and EHI were 5.0 µg/mL [interquartile range (IQR) 2.7-9.1] and 37 (IQR 26-53), respectively. EHI <20 (remission) was found in 57 (16.9%) patients. EHI ≥50 (active disease) was found in 97 (28.8%) patients. Higher proportions of subjects were in remission for increasing UST quartiles, P = 0.01. Median UST in patients with EHI <20 and EHI ≥50 were 7.5 µg/mL (IQR 4.6-10.9) and 3.1 µg/mL (IQR 1.8-6.6), respectively, P < 0.001. An UST threshold of 3.75 µg/mL optimally differentiated between active disease and remission (area under the curve 0.725). UST levels >3.75 µg/mL were associated with a lower proportion of subjects with active disease (EHI ≥50; 18.9%) compared with UST levels ≤3.75 µg/mL (45.6%, P < 0.001).

Conclusions

Using the EHI, we identified a threshold UST level of 3.75 µg/mL to optimally differentiate between active and quiescent CD. These data suggest that UST serum concentrations of >3.75 µg/mL are optimally associated with endoscopic remission in CD.

Soluble ligands as drug targets for treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, is characterized by persistent inflammation in a hereditarily susceptible host. In addition to gastrointestinal symptoms, patients with IBD frequently suffer from extra-intestinal complications such as fibrosis, stenosis or cancer. Mounting evidence supports the targeting of cytokines for effective treatment of IBD. Cytokines can be included in a newly proposed classification "soluble ligands" that has become the third major target of human protein therapeutic drugs after enzymes and receptors. Soluble ligands have potential significance for research and development of anti-IBD drugs. Compared with traditional drug targets for IBD treatment, such as receptors, at least three factors contribute to the increasing importance of soluble ligands as drug targets. Firstly, cytokines are the main soluble ligands and targeting of them has demonstrated efficacy in patients with IBD. Secondly, soluble ligands are more accessible than receptors, which are embedded in the cell membrane and have complex tertiary membrane structures. Lastly, certain potential target proteins that are present in membrane-bound forms can become soluble following cleavage, providing further opportunities for intervention in the treatment of IBD. In this review, 49 drugs targeting 25 distinct ligands have been evaluated, including consideration of the characteristics of the ligands and drugs in respect of IBD treatment. In addition to approved drugs targeting soluble ligands, we have also assessed drugs that are in preclinical research and drugs inhibiting ligand-receptor binding. Some new types of targetable soluble ligands/proteins, such as epoxide hydrolase and p-selectin glycoprotein ligand-1, are also introduced. Targeting soluble ligands not only opens a new field of anti-IBD drug development, but the circulating soluble ligands also provide diagnostic insights for early prediction of treatment response. In conclusion, soluble ligands serve as the third-largest protein target class in medicine, with much potential for the drugs targeting them.

The Evolving Role of Microsampling in Therapeutic Drug Monitoring of Monoclonal Antibodies in Inflammatory Diseases

Monoclonal antibodies (mAbs) have been extensively developed over the past few years, for the treatment of various inflammatory diseases. They are large molecules characterized by complex pharmacokinetic and pharmacodynamic properties. Therapeutic drug monitoring (TDM) is routinely implemented in the therapy with mAbs, to monitor patients’ treatment response and to further guide dose adjustments. Serum has been the matrix of choice in the TDM of mAbs and its sampling requires the visit of the patients to laboratories that are not always easily accessible. Therefore, dried blood spots (DBS) and various microsampling techniques have been suggested as an alternative. DBS is a sampling technique in which capillary blood is deposited on a special filter paper. It is a relatively simple procedure, and the patients can perform the home-sampling. The convenience it offers has enabled its use in the quantification of small-molecule drugs, whilst in the recent years, studies aimed to develop microsampling methods that will facilitate the TDM of mAbs. Nevertheless, hematocrit still remains an obstacle that hinders a more widespread implementation of DBS in clinical practice. The introduction of novel analytical techniques and contemporary microsampling devices can be considered the steppingstone to the attempts made addressing this issue.

Evaluation of ustekinumab trough levels during induction and maintenance therapy with regard to disease activity status in difficult to treat Crohn disease patients

Ustekinumab (UST) is approved for the treatment of moderate and severe Crohn disease (CD). Therapeutic drug monitoring (TDM) can help monitor the therapeutic effects of biologics. Therefore, the aim of this study was to evaluate the clinical outcomes of UST-treated CD patients and to determine the UST trough level in clinical and corticosteroid-free remission.This retrospective study included patients with moderate and severe active disease (AD) treated intravenously with a weight-adapted induction dose of UST. The maintenance therapy consisted of 90 mg UST subcutaneously at week 8 and thereafter every 8 or 12 weeks, depending on the clinical response. Clinical and corticosteroid-free remission, Harvey-Bradshaw-Index (HBI), UST trough level, and further laboratory parameters were measured just before the injection of UST at each follow-up evaluation until week 40.37 CD patients with a median HBI of 9 at week 0 were included in the study. Starting from 24% at the beginning of the monitoring period, and 38% of patients at the end of the monitoring period were treated with an 8-week interval (P = .18). There was a significant improvement in clinical (P = .0004), corticosteroid-free remission (P = .03), and HBI (P < .0001) from week 0 until the end of the observation period. The serum UST trough level decreased significantly from 2.0 at week 8 to 0.3, in the maintenance therapy and 0.4 μg/ml at the end of the therapy (P < .0001). Neither UST trough level nor levels of C-reactive protein (CRP) or fecal calprotectin (FC) were associated with disease outcome. Concomitant immunomodulator therapy did not appear to affect the UST trough level or clinical course.UST is an effective treatment option for difficult-to-treat patients with CD. UST trough levels may not be associated with treatment efficacy or the prediction of treatment outcomes in patients with CD. Further prospective randomized trials should be conducted to evaluate whether UST trough levels are associated with treatment outcomes in patients with CD.

Update on TDM (Therapeutic Drug Monitoring) with Ustekinumab, Vedolizumab and Tofacitinib in Inflammatory Bowel Disease

The goal of therapeutic drug monitoring (TDM) is to optimize anti-TNF (tumor necrosis factor) biologic treatment in patients with inflammatory bowel disease (IBD). Although commercial assays are readily available for both ustekinumab and vedolizumab, the use of TDM with these newer biologic medications is at its infancy. The clinical utility of TDM with non-anti-TNF mechanisms of action is not clear. This review summarizes the latest available data on the pharmacokinetics of newer biologic and oral small molecules and highlights the threshold concentrations that have been associated with improved outcomes in IBD patients.

How to Optimize Treatment With Ustekinumab in Inflammatory Bowel Disease: Lessons Learned From Clinical Trials and Real-World Data

Ustekinumab is a fully human IgG1 monoclonal antibody that has been approved for the treatment of moderate to severe Crohn's disease, and more recently moderate to severe ulcerative colitis. It binds with high affinity to the p40 subunit of human interleukin-12 and 23. This mechanism of action prevents the bioactivity of both interleukins, thus precluding their interaction with the cell surface receptor protein. The pivotal clinical trials (UNITI-1, UNITI-2 and IM-UNITI) demonstrated its clinical efficacy and safety, in naïve patients and also in those previously exposed to immunosuppressants and/or biologics. There is now an extensive experience with its use worldwide, corroborating its favorable profile even in patients with refractory disease. However, the number of medical treatment options available in inflammatory bowel disease are still limited. Hence, we should prioritize the treatments that have a greater probability of response in an individual patient. Our aim was to review and summarize all the available literature regarding the potential predictors of response to ustekinumab that can increase the success rate with this therapy in clinical practice.

Strengthened monitoring and optimized management of Crohn's disease patients

In recent years, the treatment goal of Crohn's disease (CD) has shifted from clinical remission to mucosal healing. In this regard, CD management and monitoring are particularly important. Timely adjustment of treatment regimen according to clinical symptoms and inflammatory markers is helpful to monitor patients and achieve better clinical and endoscopic treatment results. However, there is not enough evidence to recommend an optimal treatment regimen that considers only inflammatory markers. Therapeutic drug monitoring (TDM) has been used to improve the treatment of thiopurine and anti-tumor necrosis factor (TNF) drugs. Passive TDM is suitable for all drugs. In order to improve the clinical usefulness, the monitoring of anti-tumor necrosis factor drugs should be transformed from passive to active. The effectiveness of active TDM in optimizing non-anti-TNF biologic agents remains to be described. In addition, inflammatory markers can predict CD recurrence after surgery, and regular colonoscopy at 6-12 mo after surgery is also important. Early postoperative anti-TNF therapy should be considered in high-risk CD patients, but the optimal time for prophylactic administration of anti-TNF therapy is still controversial, and the role of non-anti-TNF biologic agents in prophylactic administration after surgery still needs to be studied. This paper mainly summarizes the monitoring of inflammatory markers, drug monitoring, and postoperative monitoring of patients, so as to optimize the management of CD patients and enable more patients to achieve the treatment goal, and emphasizes the importance of close monitoring of CD patients.