How, When, and for Whom Should We Perform Therapeutic Drug Monitoring?

Fluorescence-Based Lateral Flow Immunoassay for Quantification of Infliximab: Analytical and Clinical Performance Evaluation

BACKGROUND

Therapeutic drug monitoring of infliximab (IFX) can improve treatment outcomes; however, the temporal gap between drug concentration monitoring and subsequent availability restricts its practical application. To address this issue, an automated monitoring method, AFIAS IFX, was developed to rapidly and accurately analyze IFX concentration in blood. The analytical and clinical performances of this method were assessed to establish its clinical utility.

METHODS

The analytical performance of AFIAS IFX was evaluated according to Clinical and Laboratory Standard Institute guidelines. For clinical validation, AFIAS IFX was compared with 3 established enzyme-linked immunosorbent assay kits (LISA TRACKER, RIDASCREEN, and ImmunoGuide) using 100 consecutive samples from 28 patients treated with IFX. Passing-Bablok regression and Bland-Altman analyses were performed to compare the methods.

RESULTS

The detection and quantification limits of AFIAS IFX were 0.12 and 0.20 mcg/mL, respectively. Furthermore, AFIAS IFX analyzed samples within 10 minutes for concentrations up to 50 mcg/mL, exhibiting reproducibility (coefficient of variation [CV] ≤7.8%) and accuracy (recovery 98%-101%) with serum, plasma, and whole blood samples. Clinically, it exhibited a good correlation with the 3 established enzyme-linked immunosorbent assay kits. For patients treated with Remicade (IFX), the Passing-Bablok regression slope was 1.001-1.259, with a mean difference of -1.48 to 0.28 mcg/mL. For patients treated with CT-P13, the Passing-Bablok regression slope was 0.974-1.254, with a mean difference of -2.44 to 0.15 mcg/mL.

CONCLUSIONS

AFIAS IFX, a novel fluorescence-based lateral flow assay, exhibited excellent performance in analyzing IFX trough levels and is a potentially powerful tool for therapeutic drug monitoring in clinical settings, with opportunities for further development.

Best Practice for Therapeutic Drug Monitoring of Infliximab: Position Statement from the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

BACKGROUND

Infliximab, an anti-tumor necrosis factor monoclonal antibody, has revolutionized the pharmacological management of immune-mediated inflammatory diseases (IMIDs). This position statement critically reviews and examines existing data on therapeutic drug monitoring (TDM) of infliximab in patients with IMIDs. It provides a practical guide on implementing TDM in current clinical practices and outlines priority areas for future research.

METHODS

The endorsing TDM of Biologics and Pharmacometrics Committees of the International Association of TDM and Clinical Toxicology collaborated to create this position statement.

RESULTS

Accumulating data support the evidence for TDM of infliximab in the treatment of inflammatory bowel diseases, with limited investigation in other IMIDs. A universal approach to TDM may not fully realize the benefits of improving therapeutic outcomes. Patients at risk for increased infliximab clearance, particularly with a proactive strategy, stand to gain the most from TDM. Personalized exposure targets based on therapeutic goals, patient phenotype, and infliximab administration route are recommended. Rapid assays and home sampling strategies offer flexibility for point-of-care TDM. Ongoing studies on model-informed precision dosing in inflammatory bowel disease will help assess the additional value of precision dosing software tools. Patient education and empowerment, and electronic health record-integrated TDM solutions will facilitate routine TDM implementation. Although optimization of therapeutic effectiveness is a primary focus, the cost-reducing potential of TDM also merits consideration.

CONCLUSIONS

Successful implementation of TDM for infliximab necessitates interdisciplinary collaboration among clinicians, hospital pharmacists, and (quantitative) clinical pharmacologists to ensure an efficient research trajectory.

Attitudes, perceptions and barriers in implementing therapeutic drug monitoring for anti-TNFs in inflammatory bowel disease: a survey from the Middle East

Background

A growing body of evidence underscores the beneficial impact of therapeutic drug monitoring (TDM) on the efficacy and cost-effectiveness of anti-tumour necrosis factor (TNF) therapy in patients with inflammatory bowel disease (IBD).

Objectives

We surveyed clinician attitudes, perceptions and barriers related to TDM in IBD in the Middle East.

Design

A 15-question survey was distributed through national gastroenterological societies in five Middle Eastern countries (UAE, Saudi Arabia, Kuwait, Lebanon and Egypt).

Methods

Data on clinician characteristics, demographics, utilization patterns and obstacles related to the adoption of TDM with anti-TNFs were gathered. Logistic regression analysis was used to predict factors influencing the utilization of TDM.

Results

Among 211 respondents (82% male), 82% were consultants, 8% were physicians with an interest in gastroenterology (GI), and 6% were GI trainees. Of these, 152 met inclusion criteria, treating >5 IBD patients per month and ⩾1 with an anti-TNF per month. TDM was used in clinical practice by 78% (95% CI: 71-85) of respondents. TDM was utilized following the loss of response (LOR) in 93%, for primary non-response (PNR) in 40% and before restarting anti-TNF therapy after a drug holiday in 33% of respondents, while 34% used TDM proactively. No specific factors were associated with the use of TDM. Barriers to TDM use included cost (85%), time lag to results (71%) and lack of insurance reimbursement (65%). Overall knowledge of TDM (70%), interpretation and actioning of results (76%) or awareness of clinical guidelines (57%) were not perceived as barriers. If barriers were removed, 95% would use TDM more frequently; 93% for LOR, 60% for PNR, 50% when restarting after a drug holiday, and 54% would use TDM proactively.

Conclusion

Most gastroenterologists use TDM for LOR, with cost, time lag and insurance reimbursement being significant barriers. Addressing these barriers would increase the judicious use of reactive and proactive TDM to optimize anti-TNF therapy in IBD.

Clinical use of biologics for Crohn's disease in adults: lessons learned from real-world studies

INTRODUCTION

The therapeutic armamentarium for managing Crohn's disease (CD) has expanded significantly in recent decades. Several biologics with three different mechanisms of action [anti-tumor necrosis factor (TNF)-α, anti-integrin α4β7, and anti-IL 12/23] are currently available to manage CD.

AREA COVERED

This narrative review aims to summarize the most significant efficacy and safety data on the use of infliximab (IFX), adalimumab (ADA), vedolizumab (VDZ) and ustekinumab (UST) for the treatment of CD obtained from studies conducted in the real world (RW), compared to the results of randomized clinical trials (RCTs).

EXPERT OPINION

RW studies reported that biologic agents included in this analysis have higher remission rates and lower adverse event rates than findings from RCTs for treating patients with CD. All biological agents have proven effective and safe in RW studies, even when using biosimilars or switching to subcutaneous administration of the molecules for which they are available. Finally, anti-TNF-α agents, particularly IFX, have a higher rate of adverse events (AEs) than VDZ and UST. Therefore, patients at higher risk of AEs may benefit from other biologics than anti-TNF-α. However, further long-term RW studies are needed to confirm these findings.

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.

Point-of-care therapeutic drug monitoring of tumour necrosis factor-α inhibitors using a single step immunoassay

Therapeutic drug monitoring (TDM) of tumor necrosis factor-α (TNFα)-inhibitors adalimumab and infliximab is important to establish optimal drug dose and maximize treatment efficacy. Currently, TDM is primarily performed with ELISA techniques in clinical laboratories, resulting in a long sample-to-result workflow. Point-of-care (POC) detection of these therapeutic antibodies could significantly decrease turnaround times and allow for user-friendly home-testing. Here, we adapted the recently developed bioluminescent dRAPPID (dimeric Ratiometric Plug-and-Play Immunodiagnostics) sensor platform to allow POC TDM of infliximab and adalimumab. We applied the two best performing dRAPPID sensors, with limit-of-detections of 1 pM and 17 pM, to measure the infliximab and adalimumab levels in 49 and 40 patient serum samples, respectively. The analytical performance of dRAPPID was benchmarked with commercial ELISAs and yielded Pearson's correlation coefficients of 0.93 and 0.94 for infliximab and adalimumab, respectively. Furthermore, a dedicated bioluminescence reader was fabricated and used as a readout device for the TDM dRAPPID sensors. Subsequently, infliximab and adalimumab patient serum samples were measured with the TDM dRAPPID sensors and bioluminescence reader, yielding Pearson's correlation coefficients of 0.97 and 0.86 for infliximab and adalimumab, respectively, and small proportional differences with ELISA (slope was 0.97 ± 0.09 and 0.96 ± 0.20, respectively). The adalimumab and infliximab dRAPPID sensors, in combination with the dedicated bioluminescence reader, allow for ease-of-use TDM with a fast turnaround time and show potential for POC TDM outside of clinical laboratories.

A Review of Therapeutic Drug Monitoring in Patients with Inflammatory Bowel Disease Receiving Combination Therapy

Background: Inflammatory Bowel Disease (IBD) impacts millions worldwide, presenting a major challenge to healthcare providers and patients. The advent of biologic therapies has enhanced the prognosis, but many patients exhibit primary or secondary non-response, underscoring the need for rigorous monitoring and therapy optimization to improve outcomes. Objective: This narrative review seeks to understand the role of therapeutic drug monitoring (TDM) in optimizing treatment for IBD patients, especially for those on combination therapies of biologics and immunomodulators. Methods: A comprehensive synthesis of the current literature was undertaken, focusing on the application, benefits, limitations, and future directions of TDM in patients receiving a combination of biologic therapies and immunomodulators. Results: While biological therapies have improved outcomes, rigorous monitoring and therapy optimization are needed. TDM has emerged as a pivotal strategy, enhancing outcomes cost-effectively while reducing adverse events. While most data pertain to monotherapies, TDM's applicability also extends to combination therapy. Conclusion: TDM plays a crucial role in the treatment optimization of IBD patients on combination therapies. Further research is needed to fully understand its potential and limitations in the broader context of IBD management.

Efficacy of Early Optimization of Infliximab Guided by Therapeutic Drug Monitoring during Induction-A Prospective Trial

Therapeutic drug monitoring (TDM) during induction therapy with anti-tumor necrosis factor drugs has emerged as a strategy to optimize response to these biologics and avoid undesired outcomes related to inadequate drug exposure. This study aimed to describe clinical, biological, and endoscopic remission rates at six months in Brazilian inflammatory bowel disease (IBD) patients following a proactive TDM algorithm guided by IFX trough levels (ITL) and antibodies to IFX (ATI) levels during induction, at week six. A total of 111 IBD patients were prospectively enrolled, excluding those previously exposed to the drug. ITL ≥ 10 μg/mL was considered optimal. Patients with suboptimal ITL (<10 µg/mL) were guided according to ATI levels. Those who presented ATI ≤ 200 ng/mL underwent dose intensification in the maintenance phase, and patients with ATI > 200 ng/mL discontinued IFX. In our study, proactive TDM was associated with persistence in the IFX rate at six months of 82.9%. At that time, rates of clinical, biological, and endoscopic remission in patients under IFX treatment were 80.2%, 73.9%, and 48.1%, respectively. Applying a simplified TDM-guided algorithm during induction seems feasible and can help improve patients' outcomes in clinical practice.

Biomedical applications of MnO2 nanomaterials as nanozyme-based theranostics

Manganese dioxide (MnO₂) nanoenzymes/nanozymes (MnO₂-NEs) are 1-100 nm nanomaterials that mimic catalytic, oxidative, peroxidase, and superoxide dismutase activities. The oxidative-like activity of MnO₂-NEs makes them suitable for developing effective and low-cost colorimetric detection assays of biomolecules. Interestingly, MnO₂-NEs also demonstrate scavenging properties against reactive oxygen species (ROS) in various pathological conditions. In addition, due to the decomposition of MnO₂-NEs in the tumor microenvironment (TME) and the production of Mn²⁺, they can act as a contrast agent for improving clinical imaging diagnostics. MnO₂-NEs also can use as an in situ oxygen production system in TME, thereby overcoming hypoxic conditions and their consequences in the progression of cancer. Furthermore, MnO₂-NEs as a shell and coating make the nanosystems smart and, therefore, in combination with other nanomaterials, the MnO₂-NEs can be used as an intelligent nanocarrier for delivering drugs, photosensitizers, and sonosensitizers in vivo. Moreover, these capabilities make MnO₂-NEs a promising candidate for the detection and treatment of different human diseases such as cancer, metabolic, infectious, and inflammatory pathological conditions. MnO₂-NEs also have ROS-scavenging and anti-bacterial properties against Gram-positive and Gram-negative bacterial strains, which make them suitable for wound healing applications. Given the importance of nanomaterials and their potential applications in biomedicine, this review aimed to discuss the biochemical properties and the theranostic roles of MnO₂-NEs and recent advances in their use in colorimetric detection assays of biomolecules, diagnostic imaging, drug delivery, and combinatorial therapy applications. Finally, the challenges of MnO₂-NEs applications in biomedicine will be discussed.

Blocking interleukin-17 in psoriasis: Real-world experience from the PsoPlus cohort

BACKGROUND

Real-world studies on the use of biologics in psoriasis (Pso) are increasing, but still scarce. Trough concentrations (C_t s) of interleukin-17 inhibitors (IL-17i) seem promising for clinical decision-making, but their value in daily practice has yet to be proven.

OBJECTIVES

To report on IL-17i effectiveness, treatment modifications and C_t use in our clinic.

METHODS

Data were collected from IL-17i-treated Pso patients followed up in the PsoPlus clinic at the Dermatology department, Ghent University Hospital, Belgium. Descriptive statistics and Kaplan-Meier analysis were performed.

RESULTS

A total of 111 patients were included, counting for 134 IL-17i courses (secukinumab, ixekizumab, and brodalumab). Fifty-five per cent of the patients were bio-naive prior to IL-17i initiation. During maintenance, merely 97.0% and 77% achieved near-complete and complete skin clearance, respectively. Major reasons for treatment modification were suboptimal response (63.0%) and safety issues (9.3%). Reported modifications were switch (25.4%), dose escalation (11.9%), dose de-escalation (6.7%), treatment association (6.0%) and IL-17i stop (3.0%). Overall drug survival was 69.0 months, without difference between the different IL-17i (p = 0.078). Ixekizumab tended to have the highest survival. Drug survival was higher in bio-naive subjects compared to bio-experienced subjects (p = 0.011). C_t was measured in 20 patients and interpreted post hoc. In 85%, the clinical decision was in accordance with the C_t (e.g. substantiated need for dose escalation). For the other cases, the C_t would have led to another clinical decision if known at that time.

CONCLUSIONS

This real-world study showed that IL-17i are very effective drugs for Pso, with ixekizumab as leading biologic. Prior bio-experience seemed to impact IL-17i drug survival. Treatment modifications were mainly performed in case of insufficient response, primarily via switch and dose escalation, and least frequently in ixekizumab patients. C_t might rationalize clinical decision-making; however, there is need for standardized algorithms to corroborate its use.

A Survey of Therapeutic Drug Monitoring Status in China

OBJECTIVE

To understand the status of therapeutic drug monitoring (TDM) in China Mainland, and thus lay down the foundation for further improvement in TDM.

METHODS

In the present study, a nationwide questionnaire survey was conducted, which was distributed and collected using a mobile-based application. Clinicians, pharmacists, and clinical laboratory physicians belonging to different levels of public hospitals were involved as subjects/objects. The contents of the survey included TDM implementation in their hospital and information regarding their opinions and suggestions on TDM work. Mann-Whitney test was used to compare the difference between top tertiary hospitals and non-top tertiary hospitals.

RESULTS

A total of 475 questionnaires were collected, 383 from top tertiary hospitals (3A hospitals) and 92 from non-top tertiary hospitals (other than 3A hospitals). A total of 240 clinicians, TDM pharmacists, and clinical laboratory physicians were involved, with an effective rate of 50.5%. Top tertiary hospitals were associated with certain advantages, such as the number of TDM testing facilities, annual sample size, number of monitoring varieties, and interpretation rate of monitoring reports, compared with non-top tertiary hospitals. In particular, β-lactamase inhibitor, olanzapine, carbamazepine, and glucocorticoids seemed to be the main projects that clinicians wanted to assess. The drugs for which TDM was commonly performed included vancomycin, valproic acid, carbamazepine, phenytoin sodium, and methotrexate. The most commonly used detection methods include high-performance liquid chromatography, immunization, 2D-LC, and LC-MS. The monitoring concentration range was found to be inconsistent for most of the drugs. Currently, no unified regulation exists for TDM charges in China, which is no more than ¥200 in general. Clinicians rely on pharmacists for professional guidance. Importantly, improvement in the interpretation of monitoring reports, proficiency testing, and cooperation with clinical departments may aid in improving the level of TDM service.

CONCLUSIONS

This survey objectively reflected the current status of TDM work in hospitals in China, and provided a strong reference base for devising strategies for improvement and effective execution of TDM work.

Recent Advances in the Optimization of Anti-TNF Treatment in Patients with Inflammatory Bowel Disease

Despite the evolution in inflammatory bowel disease (IBD) management during the last 20 years owing to the advent of new advanced therapies, anti-TNF agents still remain the cornerstone of therapy for both Crohn's disease and ulcerative colitis. However, this does not only secure favorable outcomes for patients considering the progressive disease character and the high likelihood of primary or secondary loss of response. Therefore, trying to reach a better treatment approach and maximize the benefits anti-TNF agents offer, optimization strategies should be examined. It has been indicated that optimizing treatment with anti-TNF enhances drug efficacy and has been associated with improved disease outcomes and a complication-free disease course. From this perspective, we aim to provide an overview of currently available data and recent advances in the practices of anti-TNF treatment optimization. Special focus has been given to the role of therapeutic drug monitoring (TDM), as well as the utility of combining anti-TNF with an immunomodulator and the treat-to-target approach.

Higher Postinduction Infliximab Concentrations Are Associated With Favorable Clinical Outcomes in Pediatric Crohn's Disease: A Post Hoc Analysis of the REACH Trial

INTRODUCTION

Exposure-outcome relationship data show that higher infliximab concentrations are associated with better outcomes in patients with Crohn's disease (CD). However, most of these data were derived from adult patients on maintenance therapy. We aimed to investigate the association of infliximab concentrations during and early after induction therapy of infliximab with short-term and long-term clinical outcomes in a pediatric CD population.

METHODS

We conducted a post hoc analysis of the REACH trial which included pediatric patients with moderate-to-severe CD treated with infliximab (n = 103). The investigated outcomes were early clinical remission (CR) defined as a pediatric CD activity index score of ≤ 10, assessed at week 10, and long-term clinical response (LTCR) defined as a decrease from baseline in the pediatric CD activity index score of at least 15 points, with a total score of ≤ 30 and no need for drug discontinuation, assessed at weeks 30 and 54.

RESULTS

Based on multivariable logistic regression analysis, higher week 10 infliximab concentrations were independently associated with CR at week 10 (odds ratio: 1.54; 95% confidence interval: 1.06-2.22; P = 0.022) and LTCR at week 30 (odds ratio: 1.62; 95% confidence interval: 1.12-2.36; P = 0.010). Receiver operating characteristic analysis identified week 10 infliximab concentration thresholds of ≥7.1 μg/mL and ≥6.5 μg/mL to be associated with CR at week 10 and LTCR at week 30, respectively.

DISCUSSION

Higher postinduction infliximab concentrations are associated with both short-term and long-term favorable clinical outcomes in pediatric patients with CD. Tailoring dosing during induction to achieve higher infliximab exposure may lead to better outcomes in pediatric patients with CD.

Ultrasensitive therapeutic drug monitoring of methotrexate by a structure-switching aptamer with cascade primer exchange reaction

As a folate antagonist, methotrexate (MTX) has been widely used in clinics with good effects on various tumors and inflammatory diseases. While the optimum dosage and total body clearance of MTX usually varies between individuals and even low-dose MTX has side effects, high-dose MTX may cause life-threatening side effects. Therefore, a convenient and simple method toward MTX sensing is highly demanded. Herein, we report a highly sensitive and selective method for therapeutic drug monitoring (TMD) of MTX by integrating a highly specific MTX-dependent structure-switching aptamer with a primer exchange reaction-based signal amplification technique. The detection limit is down to 1.7 nM with a linear range from 0.01 to 1 μM in buffer. More importantly, the sensing strategy can effectively detect MTX in a complex bio-environment with a linear response range from 0.05 to 2 μM and a LOD of 12.4 nM in 10% FBS and a range of 0.2 to 5 μM with a LOD of 63.73 nM in 10% whole blood. Considering the high sensitivity and selectivity and good performance in blood, the method reported herein paves a new avenue for the effective determination of MTX in clinics.

Proactive Therapeutic Drug Monitoring Versus Conventional Management for Inflammatory Bowel Diseases: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Proactive therapeutic drug monitoring (TDM) has been proposed to improve outcomes in patients with inflammatory bowel disease (IBD) treated with tumor necrosis factor (TNF)α antagonists. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing proactive TDM with conventional management in patients with IBD.

METHODS

We identified RCTs in patients with IBD treated with TNFα antagonists comparing proactive TDM (routine assessments of trough concentration with dose adjustments to maintain predetermined trough concentration, regardless of disease activity) with conventional management (clinically driven dose adjustments). The primary outcome was failure to maintain clinical remission. Certainty of evidence was appraised using Grading of Recommendations, Assessment, Development and Evaluations.

RESULTS

On meta-analysis of 9 RCTs (8 RCTs in adults, and focusing on maintenance phase), there was no significant difference in the risk of failing to maintain clinical remission in patients who underwent proactive TDM (267/709; 38%) vs conventional management (292/696; 42%) (relative risk [RR], 0.96; 95% confidence interval [CI], 0.81-1.13) with moderate heterogeneity (inconsistency index = 36%) (Grading of Recommendations, Assessment, Development and Evaluations; low certainty evidence), with no differences in patients with Crohn's disease (RR, 0.87 ; 95% CI, 0.66-1.15) and ulcerative colitis (RR, 0.88; 95% CI, 0.72-1.07). Disease duration, concomitant immunomodulators, disease activity at baseline, and optimization of therapy before randomization did not modify this association. No differences were observed in risk of developing antidrug antibodies or serious adverse events. Patients in the proactive TDM arm were more likely to undergo dose escalation (RR, 1.56; 95% CI, 1.25-1.94).

CONCLUSIONS

Routine proactive TDM to target biologic concentration to specific thresholds, regardless of disease activity, did not offer clinical benefit in patients with IBD treated with TNFα antagonists in RCTs conducted to date. We cannot exclude the possibility of benefit in disease subtypes and phases of therapy (induction) not represented in these RCT populations.

Multi-utility of therapeutic drug monitoring in inflammatory bowel diseases

Inflammatory bowel disease (IBD) treatment targets have progressed over time from clinical response to clinical and endoscopic remission. Several data have shown a positive correlation between serum biologic drug concentrations and favorable therapeutic outcomes. Therapeutic drug monitoring (TDM) has evolved as an important approach for optimizing the use of immunobiologics, especially antitumor necrosis factor therapy, in patients with IBD. The use of TDM is supported by medical societies and IBD experts in different contexts; however, challenges remain due to knowledge gaps that limit the widespread use of it. The aim of this review is to assess the role of TDM in IBD, focusing on the implementation of this strategy in different scenarios and demonstrating the multi-utility aspects of this approach in clinical practice.

High Anti-Infliximab Antibody Titers Do Not Impact Response to Subsequent Adalimumab Treatment in Inflammatory Bowel Diseases

BACKGROUND

While the role of anti-drug antibodies in mediating loss of response to infliximab (IFX) is known, it is possible that there are different clinical implications for high compared to low titers of antibodies to infliximab (ATI). The impact of ATI titer on efficacy of subsequent anti-TNF treatment has not been established previously.

METHODS

This is a multicenter retrospective cohort study of individuals with IBD who discontinued infliximab due to development of ATI and were subsequently switched to adalimumab therapy. IFX anti-drug antibody titer level was measured using Mayo or Esoterix assays. We examined clinical and endoscopic response to adalimumab at 3 months, 12 months, and 2 years.

RESULTS

Our study included 90 patients (69 CD, 17 UC, 4 CD of the ileoanal pouch) with IBD. The median antibody titer levels for the Esoterix (208 u/mL) or Mayo clinic laboratory (236 u/mL) were similar (p > 0. 50). Patients with high ATI titers (median 824 u/ml, IQR 405-1250 u/ml) were as likely to respond to adalimumab as those with low titers (median 76u/ml, IQR 41-129 u/ml). At 3 months and 12 months, the rates of clinical response/remission to adalimumab therapy were 78% and 77%, respectively, among those with high ATI titers and 81% and 84% among those with low ATI titers (p = 0.81 and 0.62, respectively). In patients who initiated a different therapeutic mechanism after adalimumab, the response rates were similar to that observed with adalimumab.

CONCLUSIONS

The presence of high titers of anti-drug antibodies to IFX is not predictive of treatment failure with adalimumab.

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.

Proactive infliximab optimisation using a pharmacokinetic dashboard versus standard of care in patients with Crohn's disease: study protocol for a randomised, controlled, multicentre, open-label study (the OPTIMIZE trial)

INTRODUCTION

Preliminary data indicates that proactive therapeutic drug monitoring (TDM) is associated with better outcomes compared with empiric dose escalation and/or reactive TDM, and that pharmacokinetic (PK) modelling can improve the precision of individual dosing schedules in Crohn's disease (CD). However, there are no data regarding the utility of a proactive TDM combined PK-dashboard starting early during the induction phase, when disease activity and drug clearance are greatest. The aim of this randomised, controlled, multicentre, open-label trial is to evaluate the efficacy and safety of a proactive TDM combined PK dashboard-driven infliximab dosing compared with standard of care (SOC) dosing in patients with moderately to severely active CD.

METHODS AND ANALYSIS

Eligible adolescent and adult (aged ≥16-80 years) patients with moderately to severely active CD will be randomised 1:1 to receive either infliximab monotherapy with proactive TDM using a PK dashboard (iDose, Projections Research) or SOC infliximab therapy, with or without a concomitant immunomodulator (IMM) (thiopurine or methotrexate) at the discretion of the investigator. The primary outcome of the study is the proportion of subjects with sustained corticosteroid-free clinical remission and no need for rescue therapy from week 14 throughout week 52. Rescue therapy is defined as any IFX dose escalation other than what is forecasted by iDose either done empirically or based on reactive TDM; addition of an IMM after week 2; reintroduction of corticosteroids after initial tapering; switch to another biologic or need for CD-related surgery. The secondary outcomes will include both efficacy and safety end points, such as endoscopic and biological remission, durability of response and CD-related surgery and hospitalisation.

ETHICS AND DISSEMINATION

The protocol has been approved by the Institutional Review Board Committee of the Beth Israel Deaconess Medical Center (IRB#:2021P000391). Results will be disseminated in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT04835506.

Editorial: is there a role for monitoring intermediate anti-TNF drug concentrations in IBD?

This article is linked to Roblin et al papers. To view these articles, visit https://doi.org/10.1111/apt.16852 and https://doi.org/10.1111/apt.16893

Impact of Pharmacokinetic and Pharmacodynamic Properties of Monoclonal Antibodies in the Management of Psoriasis

The treatment of psoriasis has been revolutionized by the emergence of biological therapies. Monoclonal antibodies (mAb) generally have complex pharmacokinetic (PK) properties with nonlinear distribution and elimination. In recent years, several population pharmacokinetic/pharmacodynamic (PK/PD) models capable of describing different types of mAb have been published. This study aims to summarize the findings of a literature search about population PK/PD modeling and therapeutic drug monitoring (TDM) of mAb in psoriasis. A total of 22 articles corresponding to population PK/PD models of tumor necrosis factor (TNF)-α inhibitors (adalimumab and golimumab), interleukin (IL)-23 inhibitors (guselkumab, tildrakizumab, and risankizumab), IL-23/IL-12 inhibitor (ustekinumab), and IL-17 inhibitors (secukinumab, ixekizumab, and brodalumab) were collected. A summary of the clinical trials conducted so far in psoriasis was included, together with the current structural population PK and PD models. The most significant and clinical covariates were body weight (BW) and the presence of immunogenicity on clearance (CL). The lack of consensus on PK/PD relationships has prevented establishing an adequate dosage and, therefore, accentuates the need for TDM in psoriasis.

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.

Recent advancements in clearance monitoring of monoclonal antibodies in patients with inflammatory bowel diseases

INTRODUCTION

Less than 50% of patients with inflammatory bowel diseases (IBD) receiving monoclonal antibody (mAb) therapy achieve endoscopic remission. Poor outcomes may indicate a need for dose optimization. During therapeutic drug monitoring (TDM), drug concentrations are measured, and when found too low, dosage regimen escalations are performed. To date, benefits of TDM of mAbs in patients with IBD are uncertain.

AREAS COVERED

This review presents an overview of what clearance monitoring is, how it can be performed, and why and when it may be valuable in treating patients with IBD. Virtual patients were used for illustration. A literature search was performed to summarize current evidence for clearance monitoring in IBD and other disease settings.

EXPERT OPINION

During clearance monitoring, mAb clearance is calculated and monitored over time. Higher mAb clearance in patients with IBD has been associated with higher target load (target-mediated drug disposition), protein-losing enteropathy (fecal drug loss), and immunogenicity. Although not prospectively confirmed, clearance monitoring might facilitate identification of (yet) asymptomatic disease flares or presence of (yet) undetectable anti-drug antibodies. Furthermore, clearance monitoring may be used to predict treatment outcomes. Whether dosage regimen adjustments can modify the clearance time course and the treatment outcome is to be determined.

Ustekinumab Therapeutic Drug Monitoring-Impact on Clinical Practice: A Multicenter Cross-Sectional Observational Trial

BACKGROUND AND AIMS

The value of ustekinumab (UST) therapeutic drug monitoring (TDM) in clinical practice remains unclear. This study examined the impact of UST TDM on clinical decision making in patients with Crohn's disease (CD).

METHODS

A total of 110 consecutive UST-treated CD patients were enrolled in this multicenter, single-arm cross-sectional study. During a single study visit, clinical decisions, disease characteristics, and serum and fecal samples were obtained. The primary outcome was congruency of the actual and two hypothetical clinical decisions based on provision of UST TDM (with and without fecal calprotectin [FCP]) to participating clinicians. Decisions were compared against those of a review panel. A sub-study retrospectively measured the associations of clinical outcomes at the next follow-up visit with serum UST concentration [UST].

RESULTS

No differences in the pattern of decisions by clinicians were observed before and after provision of UST TDM (P = 1.0) or UST TDM + FCP (P = 0.86). However, 39% (TDM) and 50% (TDM + FCP) of hypothetical decisions differed from the initial decisions. The review panel's decisions differed with the addition of TDM + FCP (P = 0.0006), but not TDM alone (P = 0.16). The sub-study (n = 53) failed to detect an association between therapeutic serum [UST] at the initial study visit and clinical outcomes at the next visit.

CONCLUSIONS

In consecutive CD patients treated with UST, the addition of TDM into routine clinical practice did not significantly impact clinical decisions and there was no association between short-term clinical outcomes and serum [UST]. Further studies are warranted before clinicians routinely implement UST TDM into clinical practice.

Population pharmacokinetics of subcutaneous infliximab CT-P13 in Crohn's disease and ulcerative colitis

BACKGROUND

Infliximab is a chimeric monoclonal antibody against tumour necrosis factor-alpha for the treatment of Crohn's disease (CD) and ulcerative colitis (UC). Recently, a subcutaneous formulation of CT-P13, an infliximab biosimilar, was approved for clinical use.

AIMS

To characterise CT-P13 pharmacokinetics (PK) and its clinically relevant determinants after subcutaneous administration through population PK modelling.

METHODS

Data from a two-part Phase I study with intravenous (5 mg/kg) and variable maintenance subcutaneous dosing of CT-P13 with frequent PK sampling in patients with CD or UC were used. Population PK analysis was conducted by non-linear mixed effects modelling. Covariates affecting PK parameters were chosen based on their clinical relevance (effect size of ≥20%) using a full fixed-effect modelling approach.

RESULTS

CT-P13 PK was described by a two-compartment model with linear elimination. The half-life in a typical 70 kg patient with serum albumin of 44 g/L was 10.8 days. The typical value for clearance was 0.355 L/d, absorption constant 0.273/d, bioavailability 79.1%, central volume of distribution 3.10 L and peripheral volume of distribution 1.93 L. Clinically relevant covariates affecting clearance were body weight (+43.2% from 70 to 120 kg), the presence of anti-drug antibodies (+39%) and serum albumin concentration (+30.1% from 44 to 32 g/L). Simulated drug exposure was comparable between routes of administration for patients weighing 50 or 70 kg, but lower with subcutaneous dosing in patients weighing 120 kg.

CONCLUSIONS

This first population PK model for subcutaneous CT-P13 supports fixed subcutaneous maintenance dosing, although heavy patients had lower cumulative drug exposure.

A Practical Guide to Therapeutic Drug Monitoring of Biologic Medications for Inflammatory Bowel Disease

Therapeutic drug monitoring (TDM) is a useful strategy to optimize biologic medications for inflammatory bowel disease not responsive to standard dosing regimens. TDM is cost effective for anti-tumor necrosis factor agents in the setting of loss of response (reactive TDM). Optimizing drug dosing when patients are in remission (proactive TDM) may be beneficial in certain circumstances. However, frequently the serum drug concentration in isolation becomes the focus TDM. Additionally, the lines of reactive and proactive TDM can quickly blur in many common clinical settings. Physicians employing a TDM based strategy need to place the drug concentration in context with the inflammatory status of the patient, the underlying pharmacokinetics and pharmacodynamics of the drug, the risk of immunogenicity, and the therapeutic goals for the patient. Physicians should understand the limits of TDM and feel comfortable making therapeutic decisions with imperfect information. The goal of this narrative review is to provide a framework of questions that physicians can use to employ TDM effectively in practice.

Trough levels of ipilimumab in serum as a potential biomarker of clinical outcomes for patients with advanced melanoma after treatment with ipilimumab

Background

Immune checkpoint blockade (ICB) using anti-CTLA-4 and anti-PD-1/PD-L1 has revolutionized the treatment of advanced cancer. However, ICB is effective for only a small fraction of patients, and biomarkers such as expression of PD-L1 in tumor or serum levels of CXCL11 have suboptimal sensitivity and specificity. Exposure–response (E-R) relationships have been observed with other therapeutic monoclonal antibodies. There are many factors influencing E-R relationships, yet several studies have shown that trough levels of anti-PD-1/PD-L1 correlated with clinical outcomes. However, the potential utility of anti-CTLA-4 levels as a biomarker remains unknown.

Methods

Serum was obtained at trough levels at weeks 7 and 12 (after doses 2 and 4) from patients with advanced melanoma who received ipilimumab alone (3 mg/kg every 3 weeks for four treatments) via an expanded access program (NCT00495066). We have successfully established a proteomics assay to measure the concentration of ipilimumab in serum using an liquid chromatography with tandem mass spectrometry-based nanosurface and molecular-orientation limited proteolysis (nSMOL) approach. Serum samples from 38 patients were assessed for trough levels of ipilimumab by the nSMOL assay.

Results

We found that trough levels of ipilimumab were higher in patients who developed immune-related adverse events but did not differ based on the presence or absence of disease progression. We found that patients with higher trough levels of ipilimumab had better overall survival when grouped based on ipilimumab trough levels. Trough levels of ipilimumab were inversely associated with pretreatment serum levels of CXCL11, a predictive biomarker we previously identified, and soluble CD25 (sCD25), a prognostic biomarker for advanced melanoma, as well as C reactive protein (CRP) and interleukin (IL)-6 levels at week 7.

Conclusions

Our results suggest that trough levels of ipilimumab may be a useful biomarker for the long-term survival of patients with advanced melanoma treated with ipilimumab. The association of ipilimumab trough levels with pretreatment serum levels of CXCL11 and sCD25 is suggestive of a baseline-driven E-R relationship, and the association of ipilimumab trough levels with on-treatment levels of CRP and IL-6 is suggestive of response-driven E-R relationship. Our findings highlight the potential utility of trough levels of ipilimumab as a biomarker.

Trial registration number

NCT00495066.

Dose optimisation for Loss of Response to Vedolizumab- Pharmacokinetics and Immune Mechanisms

BACKGROUND

Real life data regarding pharmacokinetics of vedolizumab in patients needing dose optimisation are scarce. We set to examine whether pre-optimisation vedolizumab levels associate with therapy outcomes and which mechanisms explain the associations.

METHODS

A multicentre observational study assessed the outcome of dose increase in association with pre-escalation levels in vedolizumab-treated patients. SubsequentIy, α4β7 occupancy on peripheral blood [PB] and intestinal lamina propria [LP] tissues was investigated on various cellular subsets in patients undergoing lower endoscopy on infusion day. Cellular localisation of vedolizumab-bound α4β7 and effects on M1 and M2 macrophages were also explored.

RESULTS

A total of 161 inflammatory bowel disease [IBD] patients were included. Among 129/161 patients intensified during maintenance [Week 14 onward], pre-intensification trough levels were comparable or higher among those subsequently attaining post-optimisation clinical, biomarker, and endoscopic remission, compared with non-remitting patients [p = 0.09, 0.25, 0.04, respectively]. Similar results were demonstrated for those dose-optimised during induction [Week 6, n = 32]. In the immune sub-study [n = 43], free α4β7 receptors at trough were similarly low among patients with/without mucosal healing, on PB T cells [p = 0.15], LP T cells [p = 0.88], and on PB eosinophils [p = 0.08]. Integrin receptors on M1 and M2 macrophages were also saturated by low levels of vedolizumab and anti-inflammatory cytokine secretion was not increased. Co-localisation and dissociation experiments demonstrated membranal α4β7 receptors of two origins: non-internalised and newly generated α4β7, but re-binding was still complete at very low concentrations.

CONCLUSIONS

These results do not support pharmacokinetics as the mechanism responsible for loss of response to vedolizumab, nor do they support a need for higher drug concentration to enhance vedolizumab's immune effects. Higher pre-escalation levels may indicate less clearance [less severe disease] and higher likelihood of subsequent re-gained response, regardless of therapy escalation.

Therapeutic drug monitoring in inflammatory bowel disease: The dawn of reactive monitoring

Inflammatory bowel disease (IBD) is a chronic condition that significantly affects the quality of life of its patients. Biologic drugs have been the mainstay treatment in the management of IBD patients but despite their significant contribution, there remains a proportion of patients that do not respond or lose response to treatment. Therapeutic drug monitoring (TDM) involves measuring levels of serum drug concentrations and anti-drug antibodies. TDM of biologic drugs initially emerged to understand treatment failure in other immune mediated inflammatory diseases. This was then introduced in IBD to rationalize primary non-response or secondary loss of response, given that low serum drug concentrations or the formation of anti-drug antibodies are variably associated with treatment failure. The aim of this narrative review is to provide an overview regarding the current use of TDM in clinical practice and to present the evidence available regarding its use in both proactive and reactive clinical settings in preventing and managing treatment failure. This review also presents the existing evidence regarding the association of various clinical outcomes with specific thresholds of drug concentrations, in everyday practice. A narrative review of published articles and conference abstracts regarding the use of TDM in IBD management, through an electronic search using PubMed and ScienceDirect. TDM has proven to be superior and more cost effective in guiding management of patients with treatment failure compared to empiric dose escalation or change in treatment. Despite a trend towards an association between clinical outcomes and drug concentrations, proactive TDM based strategies have not been shown to achieve clear benefit in long-term outcomes. In the clinical setting, TDM has proven to be useful in managing IBD patients, and its use in the reactive setting, as an additional tool to help manage patients with treatment failure, is being promoted as newer guidelines and consensus groups implement TDM as part of the management plan.

Model-Informed Precision Dosing during Infliximab Induction Therapy Reduces Variability in Exposure and Endoscopic Improvement between Patients with Ulcerative Colitis

Model-informed precision dosing (MIPD) may be a solution to therapeutic failure of infliximab for patients with ulcerative colitis (UC), as underexposure could be avoided, and the probability of endoscopic improvement (pEI; Mayo endoscopic subscore ≤ 1) could be optimized. To investigate in silico whether this claim has merit, four induction dosing regimens were simulated: 5 mg/kg (label dosing), 10 mg/kg, covariate-based MIPD (fat-free mass, corticosteroid use, and presence of extensive colitis at baseline), and concentration-based MIPD (based on the trough concentration at day 14). Covariate- and concentration-based MIPD were chosen to target the same median area under the infliximab concentration-time curve up to endoscopy at day 84 (AUC_d84), as was predicted from 10 mg/kg dosing. Dosing at 5 mg/kg resulted in a mean ± standard deviation pEI of 55.7 ± 9.0%. Increasing the dose to 10 mg/kg was predicted to improve pEI to 65.1 ± 6.1%. Covariate-based MIPD reduced variability in exposure and pEI (65.1 ± 5.5%). Concentration-based MIPD decreased variability further (66.0 ± 3.9%) but did so at an increased average dose of 2293 mg per patient, as compared to 2168 mg for 10 mg/kg dosing. Mean pEI remained unchanged between 10 mg/kg dosing and MIPD, since the same median AUC_d84 was targeted. In conclusion, quantitative simulations predict MIPD will reduce variability in exposure and pEI between patients with UC during infliximab induction therapy.

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.

Immunogenicity of Tumor Necrosis Factor Antagonists and Effect of Dose Escalation on Anti-Drug Antibodies and Serum Drug Concentrations in Inflammatory Bowel Disease

BACKGROUND

Infliximab and adalimumab concentrations are associated with important outcomes in inflammatory bowel disease (IBD). Antibodies to infliximab (ATI) and adalimumab (ATA) are associated with reduced drug concentrations and worse outcomes. Because the efficacy of dose escalation to overcome antibodies is unclear, we assessed the impact of this strategy to overcome immunogenicity in IBD.

METHODS

Infliximab and adalimumab dosing, drug, and antibody concentrations were extracted from a database of patients with IBD having specimens collected for therapeutic drug monitoring. The primary outcome compared proportions with either infliximab ≥5 μg/mL or adalimumab ≥7.5 μg/mL and undetectable antibodies between dose-escalated and non-escalated patients. Area under the receiver operating characteristic curve analyses determined antibody concentrations below which dose escalation was associated with the primary outcome.

RESULTS

The study included 63,176 patients treated with infliximab and 46,429 patients treated with adalimumab. We detected ATI and ATA in 23.6% (n = 14,900) of patients treated with infliximab and 19.6% (n = 9101) of patients treated with adalimumab. In patients with ATI, infliximab dose escalation (n = 453) yielded higher proportions achieving the primary outcome (47.5% vs 30.9%; P < 0.001), greater drug concentration increases (5.9 μg/mL vs 0.2 μg/mL; P < 0.001), and ATI reductions (4.3 U/mL vs 1.9 U/mL; P = 0.002) compared to no escalation (n = 204). An ATI threshold of 8.55 U/mL was associated with achieving the primary outcome with dose escalation (area under the curve = 0.66). For patients with ATI ≤8.55 U/mL (n = 274), higher proportions (59.1% vs 29.6%; P < 0.001) achieved the primary outcome compared with those with ATI >8.55 U/mL (n = 179). No patients treated with adalimumab achieved the primary outcome (0/390), regardless of dose escalation (n = 87).

CONCLUSION

Dose escalation increased drug concentrations and eliminated antibodies with infliximab but not adalimumab. Initial ATI ≤8.55 U/mL was associated with increased efficacy of dose escalation using this assay.

Higher Postinduction Infliximab Concentrations Are Associated With Improved Clinical Outcomes in Fistulizing Crohn's Disease: An ACCENT-II Post Hoc Analysis

INTRODUCTION

There are only limited data regarding the role of therapeutic drug monitoring in fistulizing Crohn's disease (CD). We investigated the association between both induction and maintenance serum infliximab concentrations and favorable therapeutic outcomes in patients with fistulizing CD.

METHODS

This was a post hoc analysis of the ACCENT-II trial evaluating patients with fistulizing CD receiving induction (n = 282) and maintenance infliximab therapy (n = 139). Investigated therapeutic outcomes at both week 14 and week 54 included fistula response, complete fistula response, C-reactive protein (CRP) normalization (≤5 mg/L) in patients with an elevated baseline CRP, and a more stringent outcome of composite remission, defined as combined complete fistula response and CRP normalization. Associations between serum infliximab concentrations and outcomes were assessed by multivariable logistic regression models.

RESULTS

Higher week 14 infliximab concentrations were independently associated with week 14 fistula response (odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.02-1.32; P = 0.019), and composite remission (OR: 2.32; 95% CI: 1.55-3.49; P < 0.001). Higher week 14 infliximab concentrations were also independently associated with week 54 composite remission (OR: 2.05; 95% CI: 1.10-3.82; P = 0.023). Based on receiver operating characteristic curve analysis, week 14 infliximab concentrations thresholds with combined maximal sensitivity and specificity of ≥20.2 μg/mL at week 2, ≥15 μg/mL at week 6, and ≥7.2 μg/mL at week 14 were associated with week 14 composite remission.

DISCUSSION

Higher post-induction infliximab concentrations are associated with early and long-term favorable therapeutic outcomes in patients with fistulizing CD.

Comparison of Assays for Therapeutic Monitoring of Infliximab and Adalimumab in Patients With Inflammatory Bowel Diseases

Comparison data regarding anti-tumor necrosis factor drug concentrations in inflammatory bowel disease (IBD) between the enzyme-linked immunosorbent assay (ELISA) and the homogenous mobility shift assay (HMSA) are scarce.1-3 As decisions in clinical practice depend on the thresholds that define a therapeutic drug concentration, it is important to determine if this varies based on the type of assay used for therapeutic drug monitoring.4 We recently showed a discrepancy between a commercially available ELISA and the HMSA for both infliximab and adalimumab concentrations in patients with IBD.5 Based on the results of the study, Prometheus Laboratories (San Diego, CA) initiated a comprehensive review of their HMSA assays and found that there was an upward drift for both infliximab (from December 2017 to May 2019) and adalimumab (from August 2017 to May 2019), including when our study was performed. Prometheus Laboratories corrected the errant values and reported the revised drug concentrations to physicians (Supplementary Methods). We aimed to compare the corrected infliximab and adalimumab concentrations with the original ELISA values.

Rapid point-of-care anti-infliximab antibodies detection in clinical practice: comparison with ELISA and potential for improving therapeutic drug monitoring in IBD patients

Anti-drug antibodies can interfere with the activity of anti-tumor necrosis factor (TNF) agents by increasing drug clearance via direct neutralization. The presence of anti-drug antibodies is clinically relevant when trough drug concentrations are undetectable or sub-therapeutic. However, traditional immunoassay is not easily and rapidly accessible, making the translation of the results into treatment adjustment difficult. The availability of a point-of-care (POC) test for therapeutic drug monitoring (TDM) might represent an important step forward for improving the management of inflammatory bowel disease (IBD) patients in clinical practice. In this pilot study, we compared the results obtained with POC tests with those obtained by enzyme-linked immunosorbent assay (ELISA) in a group of IBD patients treated with Infliximab (IFX). We showed that POC test can reliably detect presence of antibody-to-IFX with 100% of specificity and 76% sensitivity, in strong agreement with the ELISA test (k-coefficient = 0.84).

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.

Personalized Medicine of Monoclonal Antibodies in Inflammatory Bowel Disease: Pharmacogenetics, Therapeutic Drug Monitoring, and Beyond

The pharmacotherapy of inflammatory bowel diseases (Crohn’s disease and ulcerative colitis) has experienced significant progress with the advent of monoclonal antibodies (mABs). As therapeutic proteins, mABs display peculiar pharmacokinetic characteristics that differentiate them from chemical drugs, such as aminosalicylates, antimetabolites (i.e., azathioprine, 6-mercaptopurine, and methotrexate), and immunosuppressants (corticosteroids and cyclosporine). However, clinical trials have demonstrated that biologic agents may suffer from a pharmacokinetic variability that could influence the desired clinical outcome, beyond primary resistance phenomena. Therefore, therapeutic drug monitoring (TDM) protocols have been elaborated and applied to adaptation drug doses according to the desired plasma concentrations of mABs. This activity is aimed at maximizing the beneficial effects of mABs while sparing patients from toxicities. However, some aspects of TDM are still under discussion, including time-changing therapeutic ranges, proactive and reactive approaches, the performance and availability of instrumental platforms, the widely varying individual characteristics of patients, the severity of the disease, and the coadministration of immunomodulatory drugs. Facing these issues, personalized medicine in IBD may benefit from a combined approach, made by TDM protocols and pharmacogenetic analyses in a timeline that necessarily considers the frailty of patients, the chronic administration of drugs, and the possible worsening of the disease. Therefore, the present review presents and discusses the activities of TDM protocols using mABs in light of the most recent results, with special attention on the integration of other actions aimed at exploiting the most effective and safe therapeutic effects of drugs prescribed in IBD patients.

Advances in Therapeutic Drug Monitoring in Biologic Therapies for Pediatric Inflammatory Bowel Disease

In the current era of treat-to-target strategies, therapeutic drug monitoring (TDM) has emerged as a potential tool in optimizing the efficacy of biologics for children diagnosed with inflammatory bowel disease (IBD). The incorporation of TDM into treatment algorithms, however, has proven to be complex. "Proactive" TDM is emerging as a therapeutic strategy due to a recently published pediatric RCT showing a clear benefit of "proactive" TDM in anti-TNF therapy. However, target therapeutic values for different biologics for different disease states [ulcerative colitis (UC) vs. Crohn's disease (CD)] and different periods of disease activity (induction vs. remission) require further definition. This is especially true in pediatrics where the therapeutic armamentarium is limited, and fixed weight-based dosing may predispose to increased clearance leading to decreased drug exposure and subsequent loss of response (pharmacokinetic and/or immunogenic). Model-based dosing for biologics offers an exciting insight into dose individualization thereby minimizing the chances of losing response. Similarly, point-of-care testing promises real-time assessment of drug levels and individualized decision-making. In the current clinical realm, TDM is being used to prolong drug durability and efficacy and prevent loss of response. Ongoing innovations may transform it into a personalized tool to achieve optimal therapeutic endpoints.

Switching biologics used in inflammatory bowel diseases: how to deal with in practice?

Inflammatory bowel disease patients do not all respond to biological treatment since several patients will initially respond but will lose response or develop side effects over time. In such cases, a switch from one biologic to another offers a valuable clinical solution. This requires to evaluate both patient and drug profiles in combination with the reason(s) for switching in order to adequately select the second-line biologic. Therapeutic drug monitoring is obviously a useful tool but is currently limited to the use of anti-TNFα. In this review paper, we provide overview and guidance on switching biologics in clinical practice, with the emphasis on the motivations for switching, the selection of the second-line biologic, as well as explanations on how and when to switch.

Correlation of serum levels of anti-tumor necrosis factor agents with perianal fistula healing in Crohn's disease: a narrative review

With the overspread use of measurement of serum levels of anti-tumor necrosis factor (TNF) agents (therapeutic drug monitoring, TDM), new therapeutic strategies have been used in the management of Crohn’s disease (CD). Different targets are correlated with increased levels of circulating drugs. Recent evidence demonstrated that higher serum levels of anti-TNF agents may be associated to better outcomes in perianal fistulizing CD (PFCD). Overall, patients with healed fistulas had higher serum levels of infliximab and adalimumab as compared to those with active drainage. This was demonstrated in some cohort studies, in induction and maintenance, in adults and children with PFCD. In this narrative review, authors summarize current evidence on the use of serum level measurement of anti-TNF agents and its correlation with perianal fistula healing in CD patients. Data on the use of TDM in PFCD is discussed in detail. The retrospective design of the studies and the lack of objective parameters to measure fistula healing are the main limitations of published data. Prospective studies, with central reading of objective radiological parameters, such as pelvic magnetic resonance imaging scores, can improve the level of evidence on the possible advantages of TDM in perianal fistula in CD and are warranted.

Dermatologists on the medical need for therapeutic drug monitoring of biologics in psoriasis: results of a structured survey

BACKGROUND

Therapeutic drug monitoring (TDM) may lead to more rational use of biologics. Still, TDM is largely underexplored in psoriasis. Little is known about the dosing behavior of biologics by dermatologists, and their attitude toward TDM.

OBJECTIVE

Exploration of the awareness and need for the concept of TDM in psoriasis amongst (inter)national dermatologists.

METHOD

A survey was distributed at the Belgian Dermatology Days 2019 and Skin Inflammation & Psoriasis International Network (SPIN) Congress 2019. Next, an online survey version was launched amongst the SPIN Scientific Committee members. We collected physician's characteristics, prescription behavior of biologics, data regarding clinical response to biologics and attitude toward TDM.

RESULTS

A total of 107 surveys were included for analysis. Most dermatologists were Belgium-based (54.2%), others from European (23.4%) or non-European countries (19.6%). Seventy percent performed either dose increase (64.8%), time interval shortening (74.6%), dose lowering (16.9%) or time interval extension (33.8%). The majority who performed dose adaptations acknowledged the need for TDM.

CONCLUSION

This study showed most dermatologists perform dose adaptations empirically. The need for TDM was indicated by the majority, implying the need for effective communication regarding availability, utility and implementation of TDM assays in daily dermatology practice.

Optimization of biologics to reduce treatment failure in inflammatory bowel diseases

Moderate to severe inflammatory bowel disease patients can fail to respond to conventional therapy and/or to biologic treatment. In the era of TNFα antagonists and other non-anti-TNF biologic drugs, it is important to review the literature on biologic treatment failure, which could be defined as primary non-response, secondary loss of response and intolerance. Therapeutic drug monitoring (TDM), that is, drug trough level and antidrug antibodies, should enable to determine the mechanisms of treatment failure and to optimize drug efficacy. There is a consensus on reactive TDM at the time of loss of response. Proactive TDM could be of interest during induction and/or maintenance, but randomized controlled trials are required.

Effectiveness And Safety Of Ustekinumab Intensification At 90 Mg Every Four Weeks In Crohn's Disease: A Multicenter Study

INTRODUCTION

The approved maintenance regimens for ustekinumab in Crohn's disease (CD) are 90 mg every 8 or 12 weeks. Some patients will partially respond to ustekinumab or will experience a secondary loss of response. It remains poorly known if these patients may benefit from shortening the interval between injections.

METHODS

All patients with active CD, as defined by Harvey-Bradshaw score ≥ 4 and one objective sign of inflammation (CRP > 5 mg/L and/or fecal calprotectin > 250 µg/g and/or radiologic and/or endoscopic evidence of disease activity) who required ustekinumab dose escalation to 90mg every 4 weeks for loss of response or incomplete response to ustekinumab 90mg every 8 weeks were included in this retrospective multicenter cohort study.

RESULTS

One hundred patients, with a median age of 35 years (Interquartile Range (IQR), 28 - 49) and median disease duration of 12 (7 - 20) years were included. Dose intensification was performed after a median of 5.0 (2.8 - 9.0) months of ustekinumab treatment and was associated with corticosteroids and immunosuppressants in respectively 29% and 27% of cases. Short-term clinical response and clinical remission were observed in respectively 61% and 31% after a median of 2.4 (1.3 - 3.0) months. After a median follow-up of 8.2 (5.6-12.4) months, 61% of patients were still treated with ustekinumab, and 26% in steroid-free clinical remission. Among the 39 patients with colonoscopy during follow-up, 14 achieved endoscopic remission (no ulcers). At the end of follow-up, 27% of patients were hospitalized, and 19% underwent intestinal resection surgery. Adverse events were reported in 12% of patients, including five serious adverse events.

CONCLUSION

In this multicenter study, two-thirds of patients recaptured response following treatment intensification with ustekinumab 90 mg every 4 weeks.

Clinical Impact of Corrections to Infliximab and Adalimumab Monitoring Results with the Homogeneous Mobility Shift Assay

An upward drift for both infliximab and adalimumab concentrations measured by the homogenous mobility shift assay (HMSA) was previously reported. We aimed to investigate the impact of this drift on clinical care of patients with inflammatory bowel disease. This was a retrospective, multicenter study. Providers reviewed the individual patient data and drug concentrations before and after the laboratory corrections and then documented whether a different clinical decision would have been made had the corrected drug concentration been originally reported. A multivariable Cox proportional hazards regression analysis was performed to investigate the association of a documented treatment change with treatment failure, defined as drug discontinuation for primary nonresponse, loss of response, or serious adverse event, adjusting for confounding factors. The study population consisted of 479 patients (infliximab, n = 219; adalimumab, n = 260). Upon review, 14.9% (71/479) patients would have had a different treatment decision made had the corrected drug concentration been initially reported. After a median follow-up of 10.6 months, 25.7% of patients (123/479) had treatment failure. A theoretical different clinical decision based on the corrected drug concentrations was not associated with treatment failure (adjusted hazard ratio (HR): 1.452; 95% confidence interval (CI): 0.805–2.618; p = 0.216), which was consistent for both infliximab (adjusted HR: 1.977; 95% CI: 0.695–5.627; p = 0.201) and adalimumab (adjusted HR: 1.484; 95% CI: 0.721–3.054; p = 0.284). The drift in infliximab and adalimumab concentrations in the HMSA assay affected treatment decisions in 15% of cases. However, this discrepancy was not associated with a higher cumulative probability for treatment failure.

Therapeutic drug monitoring in patients on biologics: lessons from gastroenterology

PURPOSE OF REVIEW

To give an overview on the role of therapeutic drug monitoring (TDM) of biologics in patients with inflammatory bowel disease (IBD).

RECENT FINDINGS

Numerous prospective exposure-response relationship studies and post-hoc analyses of randomized controlled trials (RCTs) show a positive correlation between biologic drug concentrations and favorable clinical outcomes in IBD. These studies also demonstrate that higher drug concentrations appear to be needed to achieve more stringent objective therapeutic outcomes. Reactive TDM rationalizes the management of primary nonresponse and secondary loss of response to antitumor necrosis factor (anti-TNF) therapy and is more cost-effective when compared with empiric dose optimization. Furthermore, recent data suggest that proactive TDM, with the goal of targeting a threshold drug concentration, is associated with better therapeutic outcomes when compared with empiric dose escalation and/or reactive TDM of infliximab or adalimumab. Finally, proactive TDM can also efficiently guide infliximab de-escalation or discontinuation in patients with IBD in remission.

SUMMARY

Reactive TDM is currently considered as standard of care, whereas proactive TDM is emerging as a new therapeutic strategy for better optimizing anti-TNF therapy in IBD. However, more data from prospective studies are needed before a wide implementation of TDM-based algorithms in real life clinical practice for newer biologics.