Therapeutic drug monitoring in patients on biologics: lessons from gastroenterology

Reactive Immunomodulator Addition to Infliximab Monotherapy Restores Clinical Response in Inflammatory Bowel Disease: A Meta-Analysis

BACKGROUND AND AIMS

Patients with inflammatory bowel disease (IBD) receiving infliximab (IFX) commonly experience immunogenic loss of response (LOR) by formation of anti-drug antibodies (ADAs). An immunomodulator (IMM) used in combination with initial IFX induction is known to reduce ADA development and improve clinical outcomes. We aimed to assess the impact of reactively adding an IMM to patients on IFX monotherapy.

METHODS

We conducted a retrospective cohort study and systematic review with meta-analysis of patients with IBD demonstrating immunologic LOR, with or without clinical LOR, that had an IMM (azathioprine, 6-mercaptopurine, or methotrexate) reactively added (reactive combination therapy; rCT) to combat elevated ADAs and raise IFX level. Data were extracted for pooled effect size estimation using random-effects models, and ADA and IFX trough levels were compared pre- and post-IMM initiation.

RESULTS

We identified 6 patients who received rCT due to rising ADA titers and low IFX levels. Median ADA titer decreased from 506 ng/mL (interquartile range (IQR) [416-750]) to 76.5 ng/mL (IQR [25.8-232]), an 85% decrease (p = 0.031). Median IFX trough increased from 0.4 µg/mL (IQR [0.4-0.48]) to 8.25 µg/mL (IQR [3.7-9.6]), a 20.6-fold increase (p = 0.038). Meta-analysis pooled effect size of 7 studies with 89 patients showed an 87% ADA titer reduction [95% confidence interval (CI) = 72-94%], 6.7-fold increased IFX trough (95% CI = 2.4-18.7), and 76% clinical remission rescue rate (95% CI = 59-93%).

CONCLUSIONS

These results suggest rCT is a valid rescue strategy in patients with immunogenic LOR to IFX to reduce ADA titers, restore therapeutic IFX levels, and recapture clinical remission of IBD.

De-escalation of Biologic Treatment in Inflammatory Bowel Disease: A Comprehensive Review

INTRODUCTION

Biologic therapy is an effective treatment for inflammatory bowel disease [IBD]. However due to cost and safety concerns, dose de-escalation strategies after achieving remission have been suggested.

AIM

To critically review available data on dose de-escalation of biologics [or other advanced therapies] in IBD. We will focus on studies evaluating de-escalation to standard dosing in patients initially optimised, and also on studies assessing de-escalation from standard dosing.

METHODS

A systematic bibliographic search was performed.

RESULTS

The mean frequency of de-escalation after previous dose intensification [12 studies, 1,474 patients] was 34%. The corresponding frequency of de-escalation from standard dosing [five studies, 3,842 patients] was 4.2%. The relapse rate of IBD following anti-tumour necrosis factor [TNF] de-escalation to standard dosing in patients initially dose-escalated [10 studies, 301 patients] was 30%. The corresponding relapse rate following anti-TNF de-escalation from standard dosing [nine studies, 494 patients] was 38%. The risk of relapse was lower for patients in clinical, biologic, and endoscopic/radiological remission at the time of de-escalation. A role of anti-TNF therapeutic drug monitoring in the decision to dose de-escalate has been demonstrated. In patients relapsing after de-escalation, re-escalation is generally effective. De-escalation is not consistently associated with a better safety profile. The cost-effectiveness of the de-escalation strategy remains uncertain. Finally, there is not enough evidence to recommend dose de-escalation of biologics different from anti-TNFs or small molecules.

CONCLUSIONS

Any consideration for de-escalation of biologic therapy in IBD must be tailored, taking into account the risks and consequences of a flare and patients' preferences.

Efficacy and safety of proactive drug monitoring in inflammatory bowel disease treated with anti-TNF agents: A systematic review and meta-analysis

BACKGROUND AND AIMS

A systematic review and a meta-analysis of the literature was conducted to assess efficacy and safety of proactive therapeutic drug monitoring (TDM) versus conventional management during maintenance treatment with anti-tumour necrosis factor (anti-TNFα) in patients with inflammatory bowel disease (IBD).

METHODS

A search was conducted up to January 2022 (MEDLINE, EMBASE, and the Cochrane Library). The primary outcome was the ability to maintain clinical remission at 12 months. The certainty of evidence was determined using the GRADE approach.

RESULTS

Nine studies were identified: one systematic review, six randomised clinical trials, and two cohort studies. No superior efficacy of proactive TDM [relative risk 1.16; 95% confidence interval (CI): 0.98-1.37, n=528; I2=55%] was shown. Proactive TDM could improve the durability of anti-TNFα treatment [odds ratio (OR) 0.12; 95%CI: 0.05-0.27; n=390; I2=45%), prevent acute infusion reactions (OR 0.21; 95%CI: 0.05-0.82; n=390; I2=0%), decrease adverse events (OR 0.38; 95%CI: 0.15-0.98; n=390; I2=14%), and reduce the probability of surgery, at lower economical expenditure.

CONCLUSIONS

The analysed evidence did not confirm the superiority of proactive TDM of anti-TNFα treatment over conventional management in patients with IBD, so proactive TDM should not currently be recommended.

Clinical profiles and outcomes in patients with inflammatory bowel disease receiving standard and escalated doses of targeted therapies: findings from a global real-world study

OBJECTIVE

Although dosing regimens of targeted therapies (TT) for ulcerative colitis (UC) and Crohn's disease (CD) are guided by market authorizations and clinical guidelines, little is known about clinical guideline adherence or outcomes in patients receiving escalated doses of TT due to lack of response. This real-world study explored the prevalence of dose escalation and compared outcomes between patients receiving standard and escalated TT doses.

METHODS

Data were from the 2020-2021 Adelphi Disease Specific Programme for inflammatory bowel disease, a cross-sectional survey of gastroenterologists and their UC and CD patients across five European countries and the US. Physicians provided retrospective data collection of patient demographics, clinical characteristics, treatment history, and satisfaction; patients reported quality-of-life and work productivity. Patients were grouped by TT maintenance dose; standard and escalated dose groups were compared. Outcomes were adjusted for time on current TT and severity at current TT initiation using regression analyses.

RESULTS

Of 1,241 UC and 1,477 CD patients, 19.1% and 24.1%, respectively, received escalated TT doses. Despite escalation, a substantial proportion of patients had not achieved remission, had moderate or severe disease activity, or were flaring. Most physicians were not fully satisfied with treatment in the escalated dose group and were more likely to switch patients to another treatment regimen than patients on standard dose.

CONCLUSION

Dose escalation is not always an effective approach to resolve inadequate or loss of response in UC and CD, highlighting a need for more therapeutic options or alternative treatment strategies in patients unresponsive to TT.

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.

Precision medicine and drug optimization in adult inflammatory bowel disease patients

Inflammatory bowel diseases (IBD) encompass two main entities including ulcerative colitis and Crohn's disease. Although having a common global pathophysiological mechanism, IBD patients are characterized by a significant interindividual heterogeneity and may differ by their disease type, disease locations, disease behaviours, disease manifestations, disease course as well as treatment needs. Indeed, although the therapeutic armamentarium for these diseases has expanded rapidly in recent years, a proportion of patients remains with a suboptimal response to medical treatment due to primary non-response, secondary loss of response or intolerance to currently available drugs. Identifying, prior to treatment initiation, which patients are likely to respond to a specific drug would improve the disease management, avoid unnecessary side effects and reduce the healthcare expenses. Precision medicine classifies individuals into subpopulations according to clinical and molecular characteristics with the objective to tailor preventative and therapeutic interventions to the characteristics of each patient. Interventions would thus be performed only on those who will benefit, sparing side effects and expense for those who will not. This review aims to summarize clinical factors, biomarkers (genetic, transcriptomic, proteomic, metabolic, radiomic or from the microbiota) and tools that could predict disease progression to guide towards a step-up or top-down strategy. Predictive factors of response or non-response to treatment will then be reviewed, followed by a discussion about the optimal dose of drug required for patients. The time at which these treatments should be administered (or rather can be stopped in case of a deep remission or in the aftermath of a surgery) will also be addressed. IBD remain biologically complex, with multifactorial etiopathology, clinical heterogeneity as well as temporal and therapeutic variabilities, which makes precision medicine especially challenging in this area. Although applied for many years in oncology, it remains an unmet medical need in IBD.

Management of Non-response and Loss of Response to Anti-tumor Necrosis Factor Therapy in Inflammatory Bowel Disease

Anti-tumor necrosis factor (anti-TNF) therapy has been successfully used as first-line biologic treatment for moderate-to-severe inflammatory bowel disease (IBD), in both “step-up” and “top-down” approaches, and has become a cornerstone of IBD management. However, in a proportion of patients the effectiveness of anti-TNF therapy is sub-optimal. Either patients do not achieve adequate initial response (primary non-response) or they lose response after initial success (loss of response). Therapeutic drug monitoring determines drug serum concentrations and the presence of anti-drug antibodies (ADAbs) and can help guide treatment optimization to improve patient outcomes. For patients with low drug concentrations who are ADAb-negative or display low levels of ADAbs, dose escalation is recommended. Should response remain unchanged following dose optimization the question whether to switch within class (anti-TNF) or out of class (different mechanism of action) arises. If ADAb levels are high and the patient has previously benefited from anti-TNF therapy, then switching within class is a viable option as ADAbs are molecule specific. Addition of an immunomodulator may lead to a decrease in ADAbs and a regaining of response in a proportion of patients. If a patient does not achieve a robust therapeutic response with an initial anti-TNF despite adequate drug levels, then switching out of class is appropriate. In conjunction with the guidance above, other factors including patient preference, age, comorbidities, disease phenotype, extra-intestinal manifestations, and treatment costs need to be factored into the treatment decision. In this review we discuss current evidence in this field and provide guidance on therapeutic decision-making in clinical situations.

Therapeutic drug monitoring for biological medications in inflammatory bowel disease

Therapeutic drug monitoring (TDM) is the measurement of serum drug concentrations and anti-drug-antibodies (ADA) for biologic therapies used to treat inflammatory bowel disease (IBD). The aim of this article is to review the current literature concerning reactive and proactive TDM for both adults and children with IBD. Although optimal trough concentration windows for some of these medications are not well defined, there is mounting evidence to suggest that reactive TDM is associated with favorable therapeutic outcomes, including less immunogenicity, greater drug exposure, and a decreased risk of treatment failure. Moreover, while the exact mechanism of loss of response is not fully elucidated, the vast majority of studies have reported a decreased incidence of nonresponse and secondary loss of response when TDM is implemented. Proactive TDM, while even less understood in the literature, employs a schedule of preemptive analysis of serum trough concentrations to accordingly adjust the patient's biologic dosage. Proactive TDM may decrease the need for IBD-related surgery/hospitalization, and therefore merits future studies of investigation.

Therapeutic drug monitoring in dermatology: the way towards dose optimization of secukinumab in chronic plaque psoriasis

Background

Despite the favourable efficacy profile of secukinumab, clinicians encounter varying clinical responses among patients potentially associated with under‐ and overdosing. As biologics are expensive, their rational use is crucial and evident. Therapeutic drug monitoring could guide clinicians in making decisions about treatment modifications.

Aim

In this multicentre, prospective study, we aimed to develop and validate a secukinumab immunoassay and searched for the therapeutic window in patients with psoriasis.

Methods

We determined secukinumab concentrations at trough in sera from 78 patients with psoriasis at multiple timepoints (Weeks 12, 24, 36, 48 and 52; after Week 52, measurements could be taken at an additional three timepoints) during maintenance phase, using an in‐house secukinumab immunoassay consisting of a combination of MA‐SEC66A2 as capture antibody and MA‐SEC67A9, conjugated to horseradish peroxidase, as detecting antibody. At each hospital visit, disease severity was assessed using the Psoriasis Area and Severity Index (PASI).

Results

After quantification, 121 serum samples were included for dose–response analysis. Based on a linear mixed‐effects model, secukinumab trough concentrations were found to decrease with increasing body mass index (BMI). Based on receiver operating characteristic (ROC) analysis, we concluded that the minimal effective secukinumab threshold was 39.1 mg/L in steady state, and that this was associated with a 92.7% probability of having an optimal clinical response (PASI ≤ 2 or reduction in PASI of ≥ 90%).

Conclusions

Monitoring and targeting a secukinumab trough concentration of 39.1 mg/L may be a viable treatment option in suboptimal responders. In patients with higher BMI, weight‐based dosing may be needed in order to prevent underdosing.

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.

The efficacy of immunomodulators in the prevention and suppression of anti-drug antibodies to anti-tumor necrosis factor therapy in inflammatory bowel disease

The development of biological agents against tumor necrosis factor (TNF) has revolutionized the management of inflammatory bowel disease (IBD), frequently achieving induction and maintenance of remission in both ulcerative colitis and Crohn's disease. However, a loss of response due to the development of anti-drug antibodies (ADA) is seen annually in approximately 20% of IBD patients receiving anti-TNF therapy. Current evidence suggests that the use of immunomodulators (IMM), such as thiopurines (azathioprine and 6-mercaptopurine) or methotrexate, may prevent or suppress ADA formation. In this article, we present a comprehensive review of the available literature regarding the efficacy of IMM in the prevention and suppression of ADA development to anti-TNF therapy in patients with IBD.

PBPK Modeling and Simulation and Therapeutic Drug Monitoring: Possible Ways for Antibiotic Dose Adjustment

Pharmacokinetics (PK) is a branch of pharmacology present and of vital importance for the research and development (R&D) of new drugs, post-market monitoring, and continued optimizations in clinical contexts. Ultimately, pharmacokinetics can contribute to improving patients’ clinical outcomes, helping enhance the efficacy of treatments, and reducing possible adverse side effects while also contributing to precision medicine. This article discusses the methods used to predict and study human pharmacokinetics and their evolution to the current physiologically based pharmacokinetic (PBPK) modeling and simulation methods. The importance of therapeutic drug monitoring (TDM) and PBPK as valuable tools for Model-Informed Precision Dosing (MIPD) are highlighted, with particular emphasis on antibiotic therapy since dosage adjustment of antibiotics can be vital to ensure successful clinical outcomes and to prevent the spread of resistant bacterial strains.

PBPK Modeling and Simulation of Antibiotics Amikacin, Gentamicin, Tobramycin, and Vancomycin Used in Hospital Practice

The importance of closely observing patients receiving antibiotic therapy, performing therapeutic drug monitoring (TDM), and regularly adjusting dosing regimens has been extensively demonstrated. Additionally, antibiotic resistance is a contemporary concerningly dangerous issue. Optimizing the use of antibiotics is crucial to ensure treatment efficacy and prevent toxicity caused by overdosing, as well as to combat the prevalence and wide spread of resistant strains. Some antibiotics have been selected and reserved for the treatment of severe infections, including amikacin, gentamicin, tobramycin, and vancomycin. Critically ill patients often require long treatments, hospitalization, and require particular attention regarding TDM and dosing adjustments. As these antibiotics are eliminated by the kidneys, critical deterioration of renal function and toxic effects must be prevented. In this work, clinical data from a Portuguese cohort of 82 inpatients was analyzed and physiologically based pharmacokinetic (PBPK) modeling and simulation was used to study the influence of different therapeutic regimens and parameters as biological sex, body weight, and renal function on the biodistribution and pharmacokinetic (PK) profile of these four antibiotics. Renal function demonstrated the greatest impact on plasma concentration of these antibiotics, and vancomycin had the most considerable accumulation in plasma over time, particularly in patients with impaired renal function. Thus, through a PBPK study, it is possible to understand which pharmacokinetic parameters will have the greatest variation in a given population receiving antibiotic administrations in hospital context.

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.

Surface plasmon resonance unveils important pitfalls of enzyme-linked immunoassay for the detection of anti-infliximab antibodies in patients' sera

Measurements of serum concentrations of therapeutic antibodies and anti-drug antibodies (ADA) can support clinical decisions for the management of non-responders, optimizing the therapy. In the present study we compared the results obtained by classical ELISA and a recently proposed surface plasmon resonance (SPR)-based immunoassay, in 76 patients receiving infliximab for inflammatory bowel diseases. The two methods indicated very similar serum concentrations of the drug, but there were striking differences as regards ADA. All the sera showing ADA by ELISA (14) also showed ADA by SPR, but the absolute amounts were different, being 7–490 times higher with SPR, with no correlation. Eight patients showed ADA only with SPR, and these ADA had significantly faster dissociation rate constants than those detectable by both SPR and ELISA. The underestimation, or the lack of detection, of ADA by ELISA is likely to reflect the long incubation steps which favor dissociation of the patient’s low-affinity ADA, while the commercial, high-affinity anti-infliximab antibodies used for the calibration curve do not dissociate. This problem is less important with SPR, which monitors binding in real time. The possibility offered by SPR to detect ADA in patients otherwise considered ADA-negative by ELISA could have important implications for clinicians.

The effect of aging on infliximab exposure and response in patients with inflammatory bowel diseases

AIMS

Controversies regarding infliximab treatment in elderly patients with inflammatory bowel diseases remain. We evaluated the effect of patient's age on infliximab exposure, efficacy and safety.

METHODS

Retrospective case-control data of patients receiving infliximab induction treatment were analysed. A population pharmacokinetic model was developed to estimate individual pharmacokinetic parameters. A logistic regression model was used to investigate the effect of exposure on endoscopic remission. Repeated time-to-event models were developed to describe the hazard of safety events over time.

RESULTS

A total of 104 patients (46 elderly, ≥65 years) were included. A two-compartment population pharmacokinetic model with linear elimination adequately described the data. Infliximab clearance decreased with older age, higher serum albumin, lower fat-free mass, lower C-reactive protein and absence of immunogenicity. Yet, infliximab exposure was not significantly different between elderly and nonelderly. Regardless of age, an infliximab trough concentration at week (w)14 of 15.6 mg/L was associated with a 50% probability of attaining endoscopic remission between w6 and w22. Infliximab exposure during induction treatment was not a risk factor of (severe) adverse events. The hazard of severe adverse events and malignancy increased by 2% and 7%, respectively, with increasing year of age. Concomitant immunomodulator use increased the hazard of infection by 958%, regardless of age.

CONCLUSIONS

Elderly patients attained infliximab exposure and endoscopic remission similarly to nonelderly patients. Therefore, the same infliximab trough concentration target can be used in therapeutic drug monitoring. The hazards of severe adverse events and malignancy increased with age, but not with infliximab exposure.

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.