The underlying inflammatory chronic disease influences infliximab pharmacokinetics

Infliximab in paediatric inflammatory bowel disease: External evaluation of population pharmacokinetic models

AIMS

Use of infliximab (IFX) has improved outcomes in children with inflammatory bowel disease (IBD). However, a proportion of patients does not respond to IFX or loses response over time. Population pharmacokinetic (PopPK) modelling is a promising approach for IFX dose optimization, but with the increasing number of PopPK models in literature, model evaluation is essential. The aims of this study are: (i) to validate the predictive performance of existing IFX PopPK models using a cohort of children with IBD; and (ii) to perform a Bayesian estimation of the most suitable model to predict the next IFX concentrations.

METHODS

PubMed was searched for IFX PopPK models in children. Selected models were rebuilt and analysed using R. Model performance was assessed through goodness-of-fit-plots, residuals against time, prediction error and prediction-corrected visual predictive checks. The validation cohort consisted of 73 children with IBD who were treated with IFX in our centre between 2017 and 2023 (340 IFX measurements).

RESULTS

We identified 9 PopPK models. Model bias for individual predicted values ranged from -9.29% to 8.01% compared to bias for population predicted values. The model by Vande Casteele et al. demonstrated superior performance (individual predicted bias 2.13, population predicted bias -6.11); upon Bayesian estimation, it predicted induction trough levels with median error of 12.95% but had a median error of -69% predicting maintenance concentrations.

CONCLUSION

The model by Vande Casteele et al. displayed superior performance in initial evaluations but had a high error in estimating next IFX levels and can only be used in practice to predict induction levels.

Impact of Obesity and Metabolic Syndrome on IBD Outcomes

PURPOSE OF REVIEW

The recent surge in inflammatory bowel disease (IBD) cases has paralleled a significant rise in obesity and metabolic comorbidities rates. In this article, we explore the potential influence of obesity and associated metabolic comorbidities on disease progression, complications, treatment response, surgical outcomes, health economics, and the potential impact of obesity treatment on the course of IBD.

FINDINGS

Contrary to visceral adiposity, obesity does not consistently result in an increased risk of IBD-related complications. Patients with IBD have a higher risk of acute arterial events, likely linked to systemic inflammation. Substantial evidence suggests that obesity has a negative impact on the response to IBD treatment, with this effect being most thoroughly studied in biologics and immunomodulators. The rates of overall complications and post-operative infections are higher in patients who are obese. There are limited but promising data regarding the impact of weight loss techniques, including exercise, medications, and bariatric interventions, on the outcomes in IBD. Both obesity and diabetes have adverse effects on the overall quality of life and place an increased financial burden on the IBD population. A growing body of evidence indicates a connection between obesity and associated metabolic comorbidities and negative outcomes in IBD, yet further efforts are required to fully understand this relationship.

Paediatric obesity and Crohn's disease: a descriptive review of disease phenotype and clinical course

Objectives

In an era of increasing paediatric obesity and inflammatory bowel disease (IBD), this study evaluates the disease phenotype and clinical course of Crohn's disease (CD) in paediatric patients who are obese or overweight.

Methods

This is a retrospective, single-center, descriptive observational study from January 2010 to May 2020. Participants were included if they were: aged 2 to 18 years at the time of diagnosis, had a confirmed diagnosis of CD, and met WHO criteria for overweight or obesity at the time of diagnosis or within one year before diagnosis.

Results

A total of 345 patient charts with CD were screened during the study period, with 16 patients meeting inclusion criteria. Median age of patients was 15.5 years (IQR = 13.6, 16.1). Of the 15 patients over 10 years of age, median anthropometrics at diagnosis included body mass index (BMI) of 27.2 (IQR = 24.9, 29.4) and BMI for age z-score of 1.82 (IQR = 1.58, 2.19). Presenting symptoms included abdominal pain (80.0%), diarrhea (66.7%), hematochezia (66.7%), and weight loss (26.7%). Five patients (33.3%) had obesity-related complications. Median time from symptom onset to diagnosis was 146 days (IQR = 31, 367), and median time from diagnosis to remission was 229 days (IQR = 101.8, 496.3).

Conclusions

Patients with elevated BMI and CD present with typical symptoms of IBD, although weight loss was a less common presenting symptom. Time to disease remission is delayed, and obesity-related complications are common. Primary care providers must have a high degree of clinical suspicion in patients to prevent delays to gastroenterology referral and to improve time to disease remission.

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

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

Performance of Eight Infliximab Population Pharmacokinetic Models in a Cohort of Dutch Children with Inflammatory Bowel Disease

BACKGROUND AND OBJECTIVE

Efficacy of infliximab in children with inflammatory bowel disease can be enhanced when serum concentrations are measured and further dosing is adjusted to achieve and maintain a target concentration. Use of a population pharmacokinetic model may help to predict an individual's infliximab dose requirement. The aim of this study was to evaluate the predictive performance of available infliximab population pharmacokinetic models in an independent cohort of Dutch children with inflammatory bowel disease.

METHODS

In this retrospective study, we used data of 70 children with inflammatory bowel disease (443 infliximab concentrations) to evaluate eight models that focused on infliximab pharmacokinetic models in individuals with inflammatory bowel disease, preferably aged ≤ 18 years. Predictive performance was evaluated with prior predictions (based solely on patient-specific covariates) and posterior predictions (based on covariates and infliximab trough concentrations). Model accuracy and precision were calculated with relative bias and relative root mean square error and we determined the classification accuracy at the trough concentration target of ≥ 5 mg/L.

RESULTS

The population pharmacokinetic model by Fasanmade was identified to be most appropriate for the total dataset (relative bias before/after therapeutic drug monitoring: -20.7%/11.2% and relative root mean square error before/after therapeutic drug monitoring: 84.1%/51.6%), although differences between models were small and several were deemed suitable for clinical use. For the Fasanmade model, sensitivity and specificity for maximum posterior predictions for the next infliximab trough concentration to be ≥ 5 mg/L were respectively 83.5% and 80% with an area under the receiver operating characteristic curve of 0.870.

CONCLUSIONS

In our paediatric cohort, various models provided acceptable predictive performance, with the Fasanmade model deemed most suitable for clinical use. Model-informed precision dosing can therefore be expected to help to maintain infliximab trough concentrations in the target range.

Formation and clearance of TNF-TNF inhibitor complexes during TNF inhibitor treatment

BACKGROUND AND PURPOSE

Millions of patients with inflammatory diseases are treated with tumour necrosis factor (TNF) inhibitors (TNFi). Individual treatment response varies, in part related to variable drug clearance. The role of TNF-TNFi complexes in clearance of the different TNFi is controversial. Moreover, mechanistic insight into the structural aspects and biological significance of TNF-TNFi complexes is lacking. We hypothesized a role for Fc-mediated clearance of TNF-TNFi immune complexes. Therefore, we investigated circulating TNF-TNFi complexes upon treatment with certolizumab-lacking Fc tails-in comparison with adalimumab, golimumab, infliximab and etanercept.

EXPERIMENTAL APPROACH

Drug-tolerant ELISAs were developed and used to quantify TNF during adalimumab, golimumab, etanercept, certolizumab and infliximab treatment in patients with inflammatory arthritis or ulcerative colitis for a maximum follow-up of 1 year. Effects on in vitro TNF production and Fc-mediated uptake of TNF-TNFi complexes were investigated for all five TNFi.

KEY RESULTS

Circulating TNF concentrations were >20-fold higher during certolizumab treatment compared with adalimumab, reaching up to 23.1 ng·ml-1 . Internalization of TNF-TNFi complexes by macrophages depended on Fc valency, with efficient uptake for the full antibody TNFi (three Fc tails), but little or no uptake for etanercept and certolizumab (one and zero Fc tail, respectively). TNF production was not affected by TNFi. Total TNF load did not affect clearance rate of total TNFi.

CONCLUSIONS AND IMPLICATIONS

Differences in TNFi structure profoundly affect clearance of TNF, while it is unlikely that TNF itself significantly contributes to target-mediated drug disposition of TNFi.

Antibody Drug Clearance: An Underexplored Marker of Outcomes with Checkpoint Inhibitors

Immune-checkpoint inhibitor (ICI) therapy has dramatically changed the clinical landscape for several cancers, and ICI use continues to expand across many cancer types. Low baseline clearance (CL) and/or a large reduction of CL during treatment correlates with better clinical response and longer survival. Similar phenomena have also been reported with other monoclonal antibodies (mAb) in cancer and other diseases, highlighting a characteristic of mAb clinical pharmacology that is potentially shared among various mAbs and diseases. Though tempting to attribute poor outcomes to low drug exposure and arguably low target engagement due to high CL, such speculation is not supported by the relatively flat exposure-response relationship of most ICIs, where a higher dose or exposure is not likely to provide additional benefit. Instead, an elevated and/or increasing CL could be a surrogate marker of the inherent resistant phenotype that cannot be reversed by maximizing drug exposure. The mechanisms connecting ICI clearance, therapeutic efficacy, and resistance are unclear and likely to be multifactorial. Therefore, to explore the potential of ICI CL as an early marker for efficacy, this review highlights the similarities and differences of CL characteristics and CL-response relationships for all FDA-approved ICIs, and we compare and contrast these to selected non-ICI mAbs. We also discuss underlying mechanisms that potentially link mAb CL with efficacy and highlight existing knowledge gaps and future directions where more clinical and preclinical investigations are warranted to clearly understand the value of baseline and/or time-varying CL in predicting response to ICI-based therapeutics.

A novel therapeutic vaccine targeting the soluble TNFα receptor II to limit the progression of cardiovascular disease: AtheroVax™

The burden of atherosclerotic cardiovascular disease contributes to a large proportion of morbidity and mortality, globally. Vaccination against atherosclerosis has been proposed for over 20 years targeting different mediators of atherothrombosis; however, these have not been adequately evaluated in human clinical trials to assess safety and efficacy. Inflammation is a driver of atherosclerosis, but inflammatory mediators are essential components of the immune response. Only pathogenic forms of sTNFR2 are acted upon while preserving the membrane-bound (wild-type) TNFR2 contributions to a non-pathogenic immune response. We hypothesize that the inhibition of sTNRF2 will be more specific and offer long-term treatment options. Here we describe pre-clinical findings of an sTNFR2-targeting peptide vaccine (AtheroVax™) in a mouse model. The multiple pathways to synthesis of the soluble TNFRII receptor (sTNFRII) were identified as sTNFRII(PC), sTNFRII(Δ7), and sTNFRII(Δ7,9). The sTNFRII(Δ7) peptide, NH2-DFALPVEKPLCLQR-COOH is specific to sTNFR2 based on an mRNA splice-variant in which exon 6 is joined to exon 8. The role of sTNFRII(Δ7) as a mediator of prolonged TNFα activity by preventing degradation and clearance was investigated. Inflammation is a critical driver of onset, progression and expansion of atherosclerosis. The TNFα ligand represents a driver of inflammation that is mediated by a splice variant of TNFR2, referred to as sTNFRII(Δ7). The multiple forms of TNFRII, both membrane bound and soluble, are associated with distinctly different phenotypes. sTNFRII(PC) and sTNFRII(Δ7) are not equivalent to etanercept because they lack a clearance mechanism. The unique peptide associated with sTNFRII(Δ7) contains a linear B-cell epitope with amino acids from both exon 6 and exon 8 supporting the vaccine design. Animal studies to evaluate the vaccine are ongoing, and results will be forthcoming. We describe a peptide vaccine targeting sTNFR2 in limiting the progression of atherosclerosis. A therapeutic vaccine limiting the progression of atherosclerosis will greatly contribute to the reduction in morbidity and mortality from cardiovascular disease. It is likely the vaccine will be used in combination with the current standards of care and lifestyle modifications.

Biosimilars in the treatment of rheumatoid arthritis: a pharmacokinetic overview

INTRODUCTION

As of May 2023, 19 and 18 biosimilars have been approved for the treatment of rheumatoid arthritis (RA) by the European Medicines Agency (EMA) and United States Food and Drug Administration (US FDA) respectively.

AREA COVERED

Pharmacokinetic results of phase 1 studies of approved biosimilars were reviewed by systematic literature search. The impact of immunogenicity on the pharmacokinetic data and clinical response was assessed, and the potential benefit of monitoring serum concentrations of biologic drugs is discussed. The advantage of subcutaneous CT-P13 (an infliximab biosimilar) in clinical practice is reviewed.

EXPERT OPINION

Biosimilars are approved based on the totality of evidence including comparable physiochemical properties, PK / PD profiles, and clinical efficacy and safety to the originator. To utilize biosimilars more effectively, physicians should be aware of the utility of combination DMARD therapy to reduce immunogenicity and maintain efficacy and PK profile. PK monitoring, however, is not currently recommended in clinical practice. CT-P13 subcutaneous (SC) is the first SC infliximab used for treatment of RA patients. Based on data from clinical studies and the real world, SC-infliximab is an attractive therapeutic option compared to IV formulations of infliximab based on its efficacy, pharmacokinetics, patient-reported outcomes, and safety profile.

Development and Biophysical Characterization of a Humanized FSH-Blocking Monoclonal Antibody Therapeutic Formulated at an Ultra-High Concentration

Highly concentrated antibody formulations are oftentimes required for subcutaneous, self-administered biologics. Here, we report the creation of a unique formulation for our first-in- class FSH-blocking humanized antibody, MS-Hu6, which we propose to move to the clinic for osteoporosis, obesity, and Alzheimer's disease. The studies were carried out using our Good Laboratory Practice (GLP) platform, compliant with the Code of Federal Regulations (Title 21, Part 58). We first used protein thermal shift, size exclusion chromatography, and dynamic light scattering to examine MS-Hu6 concentrations between 1 and 100 mg/mL. We found that thermal, monomeric, and colloidal stability of formulated MS-Hu6 was maintained at a concentration of 100 mg/mL. The addition of the antioxidant L-methionine and chelating agent disodium EDTA improved the formulation's long-term colloidal and thermal stability. Thermal stability was further confirmed by Nano differential scanning calorimetry (DSC). Physiochemical properties of formulated MS-Hu6, including viscosity, turbidity, and clarity, conformed with acceptable industry standards. That the structural integrity of MS-Hu6 in formulation was maintained was proven through Circular Dichroism (CD) and Fourier Transform Infrared (FTIR) spectroscopy. Three rapid freeze-thaw cycles at -80°C/25°C or -80°C/37°C further revealed excellent thermal and colloidal stability. Furthermore, formulated MS-Hu6, particularly its Fab domain, displayed thermal and monomeric storage stability for more than 90 days at 4°C and 25°C. Finally, the unfolding temperature (T _m ) for formulated MS-Hu6 increased by >4.80°C upon binding to recombinant FSH, indicating highly specific ligand binding. Overall, we document the feasibility of developing a stable, manufacturable and transportable MS-Hu6 formulation at a ultra-high concentration at industry standards. The study should become a resource for developing biologic formulations in academic medical centers.

Ulcerative Colitis and Acute Severe Ulcerative Colitis Patients Are Overlooked in Infliximab Population Pharmacokinetic Models: Results from a Comprehensive Review

Ulcerative colitis (UC) is part of the inflammatory bowels diseases, and moderate to severe UC patients can be treated with anti-tumour necrosis α monoclonal antibodies, including infliximab (IFX). Even though treatment of UC patients by IFX has been in place for over a decade, many gaps in modelling of IFX PK in this population remain. This is even more true for acute severe UC (ASUC) patients for which early prediction of IFX pharmacokinetic (PK) could highly improve treatment outcome. Thus, this review aims to compile and analyse published population PK models of IFX in UC and ASUC patients, and to assess the current knowledge on disease activity impact on IFX PK. For this, a semi-systematic literature search was conducted, from which 26 publications including a population PK model analysis of UC patients receiving IFX therapy were selected. Amongst those, only four developed a model specifically for UC patients, and only three populations included severe UC patients. Investigations of disease activity impact on PK were reported in only 4 of the 14 models selected. In addition, the lack of reported model codes and assessment of predictive performance make the use of published models in a clinical setting challenging. Thus, more comprehensive investigation of PK in UC and ASUC is needed as well as more adequate reports on developed models and their evaluation in order to apply them in a clinical setting.

Inhibition of TNF-α Restores Muscle Force, Inhibits Inflammation, and Reduces Apoptosis of Traumatized Skeletal Muscles

BACKGROUND

Muscle injuries are common in humans and are often associated with irrecoverable damage and disability. Upon muscle injury, TNF-α signaling pathways modulate the healing process and are predominantly associated with tissue degradation. In this study we assumed that TNF-α inhibition could reduce the TNF-α-associated tissue degradation after muscle injury.

MATERIALS AND METHODS

Therefore, the left soleus muscle of 42 male Wistar rats was injured using a standardized open muscle injury model. All rats were treated immediately after injury either with infliximab (single i.p. injection; 10 mg/kg b.w.) or saline solution i.p. Final measurements were conducted at day one, four, and 14 post injury. The muscle force, the muscle cell proliferation, the muscle cell coverage as well as the myofiber diameter served as read out parameters of our experiment.

RESULTS

Systemic application of infliximab could significantly reduce the TNF-α levels in the injured muscle at day four upon trauma compared to saline treated animals. The ratio of muscle weight to body weight was increased and the twitch muscle force showed a significant rise 14 days after trauma and TNF-α inhibition. Quantification of myofiber diameter in the penumbra zone showed a significant difference between both groups at day one and four after injury, indicated by muscle hypertrophy in the infliximab group. Planimetric analysis of the injured muscle at day 14 revealed increased muscle tissue fraction in the infliximab group compared to the control animals. Muscle cell proliferation did not differ between both groups.

CONCLUSIONS

These data provide evidence that the TNF-α blockade positively regulates the restauration of skeletal muscles upon injury.

Multi‐model averaging improves the performance of model‐guided infliximab dosing in patients with inflammatory bowel diseases

Infliximab dosage de‐escalation without prior knowledge of drug concentrations may put patients at risk for underexposure and trigger the loss of response. A single‐model approach for model‐informed precision dosing during infliximab maintenance therapy has proven its clinical benefit in patients with inflammatory bowel diseases. We evaluated the predictive performances of two multi‐model approaches, a model selection algorithm and a model averaging algorithm, using 18 published population pharmacokinetic models of infliximab for guiding dosage de‐escalation. Data of 54 patients with Crohn’s disease and ulcerative colitis who underwent infliximab dosage de‐escalation after an earlier escalation were used. A priori prediction (based solely on covariate data) and maximum a posteriori prediction (based on covariate data and trough concentrations) were compared using accuracy and precision metrics and the classification accuracy at the trough concentration target of 5.0 mg/L. A priori prediction was inaccurate and imprecise, with the lowest classification accuracies irrespective of the approach (median 59%, interquartile range 59%–63%). Using the maximum a posteriori prediction, the model averaging algorithm had systematically better predictive performance than the model selection algorithm or the single‐model approach with any model, regardless of the number of concentration data. Only a single trough concentration (preferably at the point of care) sufficed for accurate and precise prediction. Predictive performance of both single‐ and multi‐model approaches was robust to the lack of covariate data. Model averaging using four models demonstrated similar predictive performance with a five‐fold shorter computation time. This model averaging algorithm was implemented in the TDMx software tool to guide infliximab dosage de‐escalation in the forthcoming prospective MODIFI study (NCT04982172).

Predictor of primary response to antitumor necrosis factor-α therapy for inflammatory bowel disease: a single-center observational study

BACKGROUND

It is necessary to find reliable and appropriate predictors of primary response to anti-TNFα therapy (infliximab and adalimumab) in inflammatory bowel disease (IBD) so as to avoid treatment failure and select optimal treatment. The aim of this study is to reveal useful predictors of the response to anti-TNFα treatment from baseline to 2 months after initial administration of anti-TNFα for individual IBD patients using our pharmacokinetic and pharmacodynamic (PK/PD) model at the time of second administration.

METHODS

We retrospectively analyzed 26 IBD patients who received anti-TNFα. In the PK/PD model, inflammation was assumed to be suppressed based on the action of anti-TNFα at the rate constant of Kanti-TNFα (day-1). Kanti-TNFα0 (day-1) is Kanti-TNFα in the absence of anti-TNFα. We expressed inflammation caused by factors not affected by the action of anti-TNFα using the rate constant Kelse (day-1). Using univariate and multivariate linear regressions, we statistically analyzed factors related to the improvement of disease activity index.

RESULTS

The significant correlation between Kanti-TNFα0/Kelse and the improvement of disease activity index was shown in Crohn's disease patients (univariate: estimated value 2.4; P = 0.003; and multivariate: 1.8; P = 0.012) and ulcerative colitis patients (univariate: 0.12; P = 0.011), and no other factors were significant.

CONCLUSION

This is the first study to present a useful predictor of primary response to anti-TNFα of individual IBD patients at second administration. The Kanti-TNFα0/Kelse ratio may help to select the optimal therapeutic drug and avoid the improper continuous administration of anti-TNFα in the induction phase.

Efficacy of tofacitinib in patients with rheumatoid arthritis stratified by baseline body mass index: an analysis of pooled data from phase 3 studies

Objective

Tofacitinib is an oral Janus kinase for the treatment of rheumatoid arthritis (RA). This post hoc analysis assessed whether baseline body mass index (BMI) impacts tofacitinib efficacy in patients with RA.

Methods

Pooled data from six phase 3 studies in patients receiving tofacitinib 5 mg (N=1589) or 10 mg (N=1611) twice daily or placebo (advancing to active treatment at months 3 or 6; N=680), ±conventional synthetic disease-modifying antirheumatic drugs, were stratified by baseline BMI (<25, 25 to <30, ≥30 kg/m²). Endpoints (through to month 6) were assessed descriptively: American College of Rheumatology 20/50/70 response rates; changes from baseline (∆) in Disease Activity Score in 28 joints, erythrocyte sedimentation rate (DAS28-4(ESR)), DAS28-4(C-reactive protein), Clinical Disease Activity Index (CDAI), Health Assessment Questionnaire-Disability Index (HAQ-DI) and pain; and proportions of patients achieving DAS28-4(ESR) ≥1.2 and HAQ-DI ≥0.22 decreases from baseline, low disease activity (DAS28-4(ESR) ≤3.2 or CDAI ≤10) and radiographic non-progression (Δmodified Total Sharp Score ≤0.5; months 12 and 24). Estimates were adjusted using multivariable models for selected outcomes. Univariate/multivariable regression analyses determined predictors of month 6 outcomes.

Results

Of 3880 patients included, 1690 (43.6%), 1173 (30.2%) and 1017 (26.2%) had baseline BMI <25, 25 to <30 and ≥30 kg/m², respectively. Tofacitinib showed greater efficacy improvements versus placebo in each BMI category. Differences in efficacy outcomes (adjusted and unadjusted) were generally not clinically meaningful across BMI categories within treatment groups. In regression analyses, BMI was not consistently associated with selected outcomes.

Conclusions

Baseline BMI did not consistently affect tofacitinib response suggesting that tofacitinib is an effective oral treatment option for adults with moderate to severe RA regardless of baseline BMI, including patients with BMI ≥30 kg/m².

Trial registration numbers

NCT00814307, NCT01039688; NCT00960440; NCT00847613; NCT00856544; NCT00853385.

Emerging Roles of Adipose Tissue in the Pathogenesis of Psoriasis and Atopic Dermatitis in Obesity

Obesity is a growing epidemic worldwide, and it is also considered a major environmental factor contributing to the pathogenesis of inflammatory skin diseases, including psoriasis (PSO) and atopic dermatitis (AD). Moreover, obesity worsens the course and impairs the treatment response of these inflammatory skin diseases. Emerging evidence highlights that hypertrophied adipocytes and infiltrated immune cells secrete a variety of molecules, including fatty acids and adipokines, such as leptin, adiponectin, and a panel of cytokines/chemokines that modulate our immune system. In this review, we describe how adipose hypertrophy leads to a chronic low-grade inflammatory state in obesity and how obesity-related inflammatory factors are involved in the pathogenesis of PSO and/or AD. Finally, we discuss the potential role of antimicrobial peptides, mechanical stress and impairment of epidermal barrier function mediated by fast expansion, and dermal fat in modulating skin inflammation. Together, this review summarizes the current literature on how obesity is associated with the pathogenesis of PSO and AD, highlighting the potentially important but overlooked immunomodulatory role of adipose tissue in the skin.

The Influence of Underlying Disease on Rituximab Pharmacokinetics May be Explained by Target-Mediated Drug Disposition

BACKGROUND AND OBJECTIVES

Rituximab is an anti-CD20 monoclonal antibody approved in several diseases, including chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), rheumatoid arthritis (RA), and anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). The influence of underlying disease on rituximab pharmacokinetics has never been investigated for several cancer and non-cancer diseases simultaneously. This study aimed at assessing this influence using an integrated semi-mechanistic model accounting for target-mediated elimination of rituximab.

METHODS

Rituximab concentration-time data from five studies previously published in patients with CLL, DLBCL, FL, RA, and AAV were described using a two-compartment model with irreversible binding of rituximab to its target antigen. Both underlying disease and target antigen measurements were assessed as covariates.

RESULTS

Central volume of distribution was [95% confidence interval] 1.7-fold [1.6-1.9] higher in DLBCL than in RA, FL, and CLL, and it was 1.8-fold [1.6-2.1] higher in RA, FL, and CLL than in AAV. First-order elimination rate constants were 1.8-fold [1.7-2.0] and 1.3-fold [1.2-1.5] higher in RA, DLBCL, and FL than in CLL and AAV, respectively. Baseline latent antigen level (L₀) was 54-fold [30-94], 20-fold [11-36], and 29-fold [14-64] higher in CLL, DLBCL, and FL, respectively, than in RA and AAV. In lymphoma, L₀ increased with baseline total metabolic tumor volume (p = 6.10^-7). In CLL, the second-order target-mediated elimination rate constant (k_deg) increased with baseline CD20 count on circulating B cells (CD20_cir, p = 0.0081).

CONCLUSIONS

Our results show for the first time that rituximab pharmacokinetics is strongly influenced by underlying disease and disease activity. Notably, neoplasms are associated with higher antigen amounts that result in decreased exposure to rituximab compared to inflammatory diseases. Our model might be used to estimate unbound target amounts in upcoming studies.

Infliximab Efficacy May Be Linked to Full TNF-α Blockade in Peripheral Compartment-A Double Central-Peripheral Target-Mediated Drug Disposition (TMDD) Model

Infliximab is an anti-TNF-α monoclonal antibody approved in chronic inflammatory bowel diseases (IBD). This study aimed at providing an in-depth description of infliximab target-mediated pharmacokinetics in 133 IBD patients treated with 5 mg/kg infliximab at weeks 0, 2, 14, and 22. A two-compartment model with double target-mediated drug disposition (TMDD) in both central and peripheral compartments was developed, using a rich database of 26 ankylosing spondylitis patients as a reference for linear elimination kinetics. Population approach and quasi-steady-state (QSS) approximation were used. Concentration-time data were satisfactorily described using the double-TMDD model. Target-mediated parameters of central and peripheral compartments were respectively baseline TNF concentrations (R^C₀ = 3.3 nM and R^P₀ = 0.46 nM), steady-stated dissociation rates (K^C_SS = 15.4 nM and K^P_SS = 0.49 nM), and first-order elimination rates of complexes (k^C_int = 0.17 day⁻¹ and k^P_int = 0.0079 day⁻¹). This model showed slower turnover of targets and infliximab-TNF complex elimination rate in peripheral compartment than in central compartment. This study allowed a better understanding of the multi-scale target-mediated pharmacokinetics of infliximab. This model could be useful to improve model-based therapeutic drug monitoring of infliximab in IBD patients.

External Model Performance Evaluation of Twelve Infliximab Population Pharmacokinetic Models in Patients with Inflammatory Bowel Disease

Infliximab is approved for treatment of various chronic inflammatory diseases including inflammatory bowel disease (IBD). However, high variability in infliximab trough levels has been associated with diverse response rates. Model-informed precision dosing (MIPD) with population pharmacokinetic models could help to individualize infliximab dosing regimens and improve therapy. The aim of this study was to evaluate the predictive performance of published infliximab population pharmacokinetic models for IBD patients with an external data set. The data set consisted of 105 IBD patients with 336 infliximab concentrations. Literature review identified 12 published models eligible for external evaluation. Model performance was evaluated with goodness-of-fit plots, prediction- and variability-corrected visual predictive checks (pvcVPCs) and quantitative measures. For anti-drug antibody (ADA)-negative patients, model accuracy decreased for predictions > 6 months, while bias did not increase. In general, predictions for patients developing ADA were less accurate for all models investigated. Two models with the highest classification accuracy identified necessary dose escalations (for trough concentrations < 5 µg/mL) in 88% of cases. In summary, population pharmacokinetic modeling can be used to individualize infliximab dosing and thereby help to prevent infliximab trough concentrations dropping below the target trough concentration. However, predictions of infliximab concentrations for patients developing ADA remain challenging.

Infliximab Treatment Does Not Lead to Full TNF-α Inhibition: A Target-Mediated Drug Disposition Model

BACKGROUND AND OBJECTIVE

Infliximab, an anti-tumour necrosis factor (TNF)-α monoclonal antibody, has been approved in chronic inflammatory disease, including rheumatoid arthritis, Crohn's disease and ankylosing spondylitis. This study aimed to investigate and characterise target-mediated drug disposition of infliximab and antigen mass turnover during infliximab treatment.

METHODS

In this retrospective cohort of 186 patients treated with infliximab for rheumatoid arthritis, Crohn's disease or ankylosing spondylitis, trough infliximab concentrations were determined from samples collected between weeks 0 and 22 after treatment initiation. Target-mediated pharmacokinetics of infliximab was described using target-mediated drug disposition modelling. Target-mediated elimination parameters were determined for rheumatoid arthritis and Crohn's disease, assuming ankylosing spondylitis with no target-mediated elimination.

RESULTS

The quasi-equilibrium approximation of a target-mediated drug disposition model allowed a satisfactory description of infliximab concentration-time data. Estimated baseline TNF-α amounts were similar in Crohn's disease and rheumatoid arthritis (R0 = 0.39 vs 0.46 nM, respectively), but infliximab-TNF complex elimination was slower in Crohn's disease than in rheumatoid arthritis (k_int = 0.024 vs 0.061 day^-1, respectively). Terminal elimination half-lives were 13.5, 21.5 and 16.5 days for rheumatoid arthritis, Crohn's disease and ankylosing spondylitis, respectively. Estimated amounts of free target were close to baseline values before the next infusion suggesting that TNF-α inhibition may not be sustained over the entire dose interval.

CONCLUSIONS

The present study is the first to quantify the influence of target antigen dynamics on infliximab pharmacokinetics. Target-mediated elimination of infliximab may be complex, involving a multi-scale turnover of TNF-α, especially in patients with Crohn's disease. Additional clinical studies are warranted to further evaluate and fine-tune dosing approaches to ensure sustained TNF-α inhibition.

External Evaluation of Population Pharmacokinetic Models and Bayes-Based Dosing of Infliximab

Despite the well-demonstrated efficacy of infliximab in inflammatory diseases, treatment failure remains frequent. Dose adjustment using Bayesian methods has shown in silico its interest in achieving target plasma concentrations. However, most of the published models have not been fully validated in accordance with the recommendations. This study aimed to submit these models to an external evaluation and verify their predictive capabilities. Eight models were selected for external evaluation, carried out on an independent database (409 concentrations from 157 patients). Each model was evaluated based on the following parameters: goodness-of-fit (comparison of predictions to observations), residual error model (population weighted residuals (PWRES), individual weighted residuals (IWRES), and normalized prediction distribution errors (NPDE)), and predictive performances (prediction-corrected visual predictive checks (pcVPC) and Bayesian simulations). The performances observed during this external evaluation varied greatly from one model to another. The eight evaluated models showed a significant bias in population predictions (from -7.19 to 7.38 mg/L). Individual predictions showed acceptable bias and precision for six of the eight models (mean error of -0.74 to -0.29 mg/L and mean percent error of -16.6 to -0.4%). Analysis of NPDE and pcVPC confirmed these results and revealed a problem with the inclusion of several covariates (weight, concomitant immunomodulatory treatment, presence of anti-drug antibodies). This external evaluation showed satisfactory results for some models, notably models A and B, and highlighted several prospects for improving the pharmacokinetic models of infliximab for clinical-biological application.

Obesity in inflammatory bowel disease: A review of its role in the pathogenesis, natural history, and treatment of IBD

In contrast to previous perceptions that inflammatory bowel disease (IBD) patients are generally malnourished and underweight, there is mounting evidence to suggest that rates of obesity in IBD now mirror that of the general population. IBD is an immune-mediated condition that appears to develop in individuals who have not only a genetic predisposition to immune dysregulation but also likely exposure to various environmental factors which further potentiate this risk. With the surge in obesity alongside the rising incidence of IBD, particularly in developing nations, the role that obesity may play, not only in the pathogenesis but also in the natural history of disease has become a topic of growing interest. Currently available data exploring obesity's impact on the natural history of IBD are largely conflicting, potentially limited by the use of body mass index as a surrogate measure of obesity at varying time points throughout the disease course. While there are pharmacokinetic data to suggest possible detrimental effects that obesity may have on the response to medical therapy, results in this realm are also inconsistent. Moreover, not only is it unclear whether weight loss improves IBD outcomes, little is known about the safety and efficacy of available weight-loss strategies in this population. For these reasons, it becomes increasingly important to further understand the nature of any interaction between obesity and IBD.

Multicenter Study of Secukinumab Survival and Safety in Spondyloarthritis and Psoriatic Arthritis: SEcukinumab in Cantabria and ASTURias Study

Objectives: We aimed to evaluate the drug retention rate and safety of secukinumab (SEC) in patients with axial spondyloarthritis (AxSpA) and psoriatic arthritis (PsA) in a real clinical setting.

Methods: This multicenter retrospective observational study included all AxSpA and PsA patients who received at least one dose of SEC. Adverse events (AE) and the drug retention rate were the main study outcomes. Drug survival was analyzed by Kaplan-Meier curves while predictive factors of discontinuation were evaluated using a Cox regression analysis. The weight of these associations was estimated by hazard ratio (HR) values.

Results: We included 154 patients (59 PsA and 95 AxSpA). Mean disease duration was 6.5 years (IQR 2-8). Sixty-one percent of patients were treated with two or more biologics prior to SEC. The 1 and 2-year retention rates for SEC were 66 and 43%, respectively. The main causes of discontinuation were inefficacy (59%) and AE (36%). The factors associated with lower risk of discontinuation were male gender (HR 0.54, 95% CI 0.38-0.78 p = 0.001), obesity (HR 0.53, 95% CI 0.30-0.93 p = 0.027), hypertension (HR 0.55, 95% CI 0.30-0.93 p = 0.008), and diabetes (HR 0.42 95% CI 0.18-0.99 p = 0.047) while number of previous biologics and depression were predictors of discontinuation (HR 1.18, 95% CI 1.04-1.34 p = 0.011 and HR 2.53, 95% CI 1.61-3.96 p < 0.001).

Conclusions: SEC showed a good retention rate in a population previously exposed to several biological therapies. As a novelty, cardiometabolic comorbidities were associated with better drug survival.

Body Mass Index Does Not Impact Clinical Efficacy of Ustekinumab in Crohn's Disease: A Post Hoc Analysis of the IM-UNITI Trial

BACKGROUND

This post hoc analysis aimed to evaluate the impact of BMI on the efficacy of ustekinumab in the IM-UNITI study.

METHODS

The relationship between body mass index (BMI) and efficacy of ustekinumab was evaluated using data from a 44-week maintenance study of ustekinumab in Crohn's disease (IM-UNITI, NCT01369355, YODA #2019-4105). The primary endpoints of interest were clinical remission (CR), defined as Crohn's disease activity index <150 and corticosteroid-free CR at week 44. Patients were stratified into the following subgroups according to their BMI at study entry: underweight <18.5 kg/m2, normal 18.5 to 25 kg/m2, overweight 25 to <30 kg/m2, and obese ≥30 kg/m2. The χ 2 test of linear trend was conducted for comparisons of frequencies between the 3 cohorts. Multivariate regression analyses evaluated possible association between BMI and efficacy outcomes of CR and corticosteroid-free CR, with adjustment for variables found significant on univariate analyses. Results are presented as odds ratios with 95% confidence intervals. Data were analyzed using Stata/IC 15.

RESULTS

A total of 254 patients treated with ustekinumab were included in this analysis. At week 44 of IM-UNITI, rates of CR did not differ among those whose BMI was underweight (67.9%%; 19 of 28 patients), normal (51.3%; 60 of 117), overweight (45.1%; 32 of 71), or obese (55.3%; 21 of 38; P = 0.89). Multivariate logistic analysis did not find BMI to be a significant predictor of CR when adjusted for covariates. Ustekinumab drug level at week 44 was significantly lower in obese patients (median level 2.98 mcg/mL; interquartile range [IQR], 2.86) compared with patients who were overweight (4.84 mcg/mL; IQR, 3.51; P = 0.021) or had underweight or normal BMI (4.43 mcg/m;, IQR, 2.82; P = 0.014).

CONCLUSIONS

Although BMI impacts ustekinumab drug levels, there was no impact of BMI on clinical efficacy. Further studies of the pharmacodynamic effects of ustekinumab in patients with high BMI are needed.

Changes in Anthropometric Parameters After Anti-TNFα Therapy in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

Background

Tumour necrosis factor (TNF)-α inhibitors have been widely used for the treatment of moderate-to-severe inflammatory bowel disease (IBD). TNFα also plays an important role in the regulation of weight homeostasis and metabolism and has been linked to variations in anthropometric responses. This relationship in patients with IBD has yet to be determined.

Objectives

Our objective was to evaluate the effects of TNFα inhibitors on changes in anthropometric measures in both adults and children with IBD through a systematic review and meta-analysis.

Methods

Multiple database searches identified studies involving children and adults with IBD and treated with TNFα inhibitors and reporting at least one primary outcome measure. Where possible, data were combined for meta-analysis. The primary outcomes included weight, body mass index (BMI), waist circumference, height, height/velocity, and fat and lean mass. Secondary outcomes included surrogate markers of disease activity. A random-effects model was used to estimate the standardised mean difference (SMD).

Results

In total, 23 cohort studies (total 1167 participants) met the inclusion criteria. Meta-analysis was performed on 13 of these studies. In children, 6–29.3 months of anti-TNFα therapy had a small but statistically significant effect on weight (SMD 0.31; 95% confidence interval [CI] 0.12–0.49; P = 0.001) with a mean gain in z score of 0.30 (standard error [SE] 0.12). In adults, 2–22.4 months of treatment had a moderate effect on BMI (SMD 0.72; 95% CI 0.17–1.26; P = 0.010; mean gain 1.23 kg/m²; SE 0.21). A small but statistically significant increase in BMI z score was found in children (SMD 0.28; 95% CI 0.03–0.53; P = 0.026; mean change 0.31 ± standard deviation [SD] 0.14) after 12–29.3 months of therapy. A meta-analysis of four studies found a negligible but statistically significant increase in height (SMD 0.16; 95% CI 0.06–0.26; P = 0.002; mean change 0.17 z score [SE 0.05]). A negligible effect on fat mass (SMD 0.24; 95% CI −0.19–0.66; P = 0.272) was found in a meta-analysis of five studies. Of note, despite the high heterogeneity among the studies that addressed the issue, these results were also consistently supported by findings from studies not included in the meta-analysis and reviewed in the systematic review. Unfortunately, a lack of data meant we were unable to perform moderator analysis on observed heterogeneity.

Conclusion

Anti-TNFα treatment appears to be associated with an increase in body weight, BMI, and other anthropometric parameters. Given the differing courses of IBD between children and adults, this association should be considered before initiating biologics for undernourished, overweight, and obese patients.

Registration: PROSPERO registration number CRD42020163079.

Electronic supplementary material

The online version of this article (10.1007/s40259-020-00444-9) contains supplementary material, which is available to authorized users.

Beyond Rheumatoid Arthritis Evaluation: What are We Missing?

Rheumatoid Arthritis (RA) is a chronic inflammatory autoimmune systemic disease that preferentially affects small and large joints with a progressive course and can become deforming and disabling. In recent years, much progress has been made in the evaluation of inflammation and disease activity, however, there are other factors that have a high impact on the quality of life of these patients, such as depression, anxiety, fatigue, sleep disorders, suicidal behavior, fibromyalgia, sexual activity, sarcopenia, frailty, cachexia and obesity that are not always evaluated by rheumatologists. This review shows that the evaluation and timely detection of these aspects in patients with RA could interfere with the prognosis and improve their quality of life.

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.

Body Mass Index and Disease Activity in Chronic Inflammatory Rheumatic Diseases: Results of the Cardiovascular in Rheumatology (Carma) Project

OBJECTIVE

Since obesity has been associated with a higher inflammatory burden and worse response to therapy in patients with chronic inflammatory rheumatic diseases (CIRD), we aimed to confirm the potential association between body mass index (BMI) and disease activity in a large series of patients with CIRDs included in the Spanish CARdiovascular in rheuMAtology (CARMA) registry.

METHODS

Baseline data analysis of patients included from the CARMA project, a 10-year prospective study of patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA) attending outpatient rheumatology clinics from 67 Spanish hospitals. Obesity was defined when BMI (kg/m²) was >30 according to the WHO criteria. Scores used to evaluate disease activity were Disease Activity Score of 28 joints (DAS28) in RA, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in AS, and modified DAS for PsA.

RESULTS

Data from 2234 patients (775 RA, 738 AS, and 721 PsA) were assessed. The mean ± SD BMI at the baseline visit were: 26.9 ± 4.8 in RA, 27.4 ± 4.4 in AS, and 28.2 ± 4.7 in PsA. A positive association between BMI and disease activity in patients with RA (β = 0.029; 95%CI (0.01- 0.05); p = 0.007) and PsA (β = 0.036; 95%CI (0.015-0.058); p = 0.001) but not in those with AS (β = 0.001; 95%CI (-0.03-0.03); p = 0.926) was found. Disease activity was associated with female sex and rheumatoid factor in RA and with Psoriasis Area Severity Index and enthesitis in PsA.

CONCLUSIONS

BMI is associated with disease activity in RA and PsA, but not in AS. Given that obesity is a potentially modifiable factor, adequate control of body weight can improve the outcome of patients with CIRD and, therefore, weight control should be included in the management strategy of these patients.

Impact of baseline body mass index on the efficacy and safety of tofacitinib in patients with psoriatic arthritis

OBJECTIVES

This post-hoc analysis explored the impact of body mass index (BMI) on tofacitinib efficacy/safety in patients with active psoriatic arthritis (PsA).

METHODS

Data were pooled from two phase 3 studies (NCT01877668; NCT01882439). Analyses included patients randomised to tofacitinib 5/10 mg twio times a day or placebo, stratified by baseline BMI: <25 kg/m2, ≥25-<30 kg/m2, ≥30-<35 kg/m2 or ≥35 kg/m2. Endpoints (month 3): American College of Rheumatology (ACR20/50/70), Health Assessment Questionnaire-Disability Index (HAQ-DI) and Psoriasis Area and Severity Index (PASI) 75 response rates; dactylitis/enthesitis resolution rates; changes from baseline Short Form-36 Health Survey version 2 (SF-36v2) Physical/Mental Component Summary (PCS) scores and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) total score. Safety was also reported.

RESULTS

Analysis included 710 patients; 43.8% were obese (BMI ≥30 kg/m2). Tofacitinib demonstrated higher efficacy response rates at month 3, compared with placebo, regardless of baseline BMI. Generally, ACR20/50/70 and HAQ-DI response rates, enthesitis resolution rates and changes from baseline in SF-36v2 PCS score and FACIT-F total score (month 3) were reduced in patients with baseline BMI ≥35 kg/m2 versus patients with lower BMIs. Elevated alanine aminotransferase/aspartate aminotransferase levels were reported in patients with baseline BMI ≥35 kg/m2 receiving tofacitinib 5 mg but not 10 mg two times a day.

CONCLUSION

Tofacitinib demonstrated greater efficacy than placebo in patients with PsA, regardless of baseline BMI. For all treatment arms, reduced efficacy was observed in patients with baseline BMI ≥35 kg/m2. Safety was generally comparable across BMI categories, although the effect of tofacitinib on liver enzymes in patients with baseline BMI ≥35 kg/m2 was inconclusive.

Therapeutic drug monitoring of anti-tumour necrosis factor-α agents in inflammatory bowel disease: Limits and improvements

AIMS

Since the publication of the American Gastroenterological Association's recommendations in 2017, there have been no significant changes in the biological monitoring recommendations in inflammatory bowel disease. Possible limitations are the lack of evidence to recommend proactive therapeutic drug monitoring (pTDM) over reactive TDM (rTDM), and the limited information about individualized dosing methods. This article aims to review the TDM strategy updates and the use of individualized dosing methods.

METHODS

For the analysis of the TDM strategies and individualized dosing method, a search was carried out in PubMed and Cochrane Central. In the TDM case, since August 2017.

RESULTS

A total of 263 publications were found, but only 7 related to proactive TDM. Five of these publications directly compared pTDM vs rTDM and 2 were randomized clinical trials. Six studies found benefits of pTDM and 1 found no differences. Regarding the individualized dosing method, 229 distinct results were found. Population pharmacokinetics was the most widely used method to develop individual dosage models and to analyse the influence of factors on drug concentrations (albumin concentration, weight, presence of anti-drug antibodies etc).

CONCLUSION

We have found no major changes in TDM strategies. There is a growing trend towards the use of pTDM because it has shown a longer duration of treatment response, lower rates of discontinuation and relapses. However, the available evidence is limited and of low quality. Despite the common use of population pharmacokinetic methods to analyse pharmacokinetic factors, they are not commonly used for personalized dosing.

Influence of Antigen Mass on the Pharmacokinetics of Therapeutic Antibodies in Humans

Therapeutic antibodies are increasingly used to treat various diseases, including neoplasms and chronic inflammatory diseases. Antibodies exhibit complex pharmacokinetic properties, notably owing to the influence of antigen mass, i.e. the amount of antigenic targets to which the monoclonal antibody binds specifically. This review focuses on the influence of antigen mass on the pharmacokinetics of therapeutic antibodies quantified by pharmacokinetic modelling in humans. Out of 159 pharmacokinetic studies, 85 reported an influence of antigen mass. This influence led to non-linear elimination decay in 50 publications, which was described using target-mediated drug disposition or derived models, as quasi-steady-state, irreversible binding and Michaelis-Menten models. In 35 publications, the pharmacokinetics was apparently linear and the influence of antigen mass was described as a covariate of pharmacokinetic parameters. If some reported covariates, such as the circulating antigen level or tumour size, are likely to be correlated to antigen mass, others, such as disease activity or disease type, may contain little information on the amount of antigenic targets. In some cases, antigen targets exist in different forms, notably in the circulation and expressed at the cell surface. The influence of antigen mass should be soundly described during the early clinical phases of drug development. To maximise therapeutic efficacy, sufficient antibody doses should be administered to ensure the saturation of antigen targets by therapeutic antibodies in all patients. If necessary, antigen mass should be taken into account in routine clinical practice.

Modeling and Simulation of the Pharmacokinetics and Target Engagement of an Antagonist Monoclonal Antibody to Interferon-γ-Induced Protein 10, BMS-986184, in Healthy Participants to Guide Therapeutic Dosing

BMS‐986184 is a human, second‐generation, anti–interferon‐γ–induced protein 10 (IP‐10) monoclonal antibody. In this study the pharmacokinetics and target engagement (TE) of BMS‐986184 in healthy participants were characterized using population‐based target‐mediated drug disposition (TMDD) modeling and data from a first‐in‐human study (NCT02864264). The results of the first‐in‐human study and the model generated were used to conduct stochastic simulations of a virtual population of healthy participants to predict pharmacokinetic exposures and TE responses for different dosage regimens. A 2‐compartment, 2‐target, TMDD structural model, assuming quasi‐steady‐state and stimulated production on treatment, was developed by simultaneous fitting of the total drug, serum‐free IP‐10, and serum total IP‐10 concentration data, with the second unobservable target contribution to drug elimination described by the Michaelis‐Menten elimination term. Model evaluation confirmed agreement between model predictions and observed data. Simulation of a virtual population of healthy individuals demonstrated that steady state was reached at the eighth dosing interval, and that around 150 mg subcutaneously every other week could be a suitable target dosage regimen for future clinical trials. Integrated modeling strategies such as this can be used to help guide rational clinical trial development of drugs with TMDD, leading to improved dose selection and greater patient benefits.

Factors Influencing Drug Disposition of Monoclonal Antibodies in Inflammatory Bowel Disease: Implications for Personalized Medicine

Monoclonal antibody (mAb) therapies have revolutionized the treatment of several chronic inflammatory diseases, including the inflammatory bowel diseases (IBD), Crohn's disease, and ulcerative colitis. While efficacious, responses to these therapies vary considerably from patient to patient, due in part to inter- and intra-individual variability in pharmacokinetics (PK) and drug exposure. The concept of personalized medicine to monitor drug exposure and to adjust dosing in individual patients is consequently gaining acceptance as a powerful tool to optimize mAb therapy for improved outcomes in IBD. This review provides a brief overview of the different mAbs currently approved or in development for the treatment of IBD, including their presumed mechanisms of action and PK properties. Specifically described are (1) the factors known to affect mAb PK and drug exposure in patients with IBD, (2) the value of population PK/pharmacodynamic (PD) modeling to identify and understand the influence of these factors on drug exposure and effect, and (3) the clinical evidence for the potential of therapeutic drug monitoring (TDM) to improve IBD outcomes in response to mAb-based therapy. Incorporation of PK/PD parameters into clinical decision support tools has the potential to guide therapeutic decision making and aid implementation of personalized medicine strategies in patients with IBD.

High body mass index is not associated with increased treatment failure in infliximab treated pediatric patients with inflammatory bowel disease

Background and Aim

While weight gain during infliximab therapy in inflammatory bowel disease (IBD) is common, there has been limited research evaluating its impact on infliximab efficacy.

Methods

Primary aims of this study were to determine the frequency of excess weight gain (body mass index [BMI] > 25 kg/m²) in children with IBD on maintenance infliximab and evaluate the impact on infliximab dosing, serum trough levels, and treatment failure. Secondary aims were to determine differences in weight gain, treatment characteristics, and clinical/biochemical variables between patients with therapeutic and subtherapeutic maintenance therapy trough levels. We performed a retrospective study of 253 pediatric IBD (75.1% Crohn's disease, 23.3% ulcerative colitis, 1.6% IBD-unclassified) patients on infliximab followed at BC Children's Hospital between January 2013 and January 2018.

Results

Median age at infliximab initiation was 13.9 years, median length of follow up was 56.9 months, and 55.7% were males; 10.3% of the cohort demonstrated excess weight gain (7.5% overweight, 2.8% obese). Average mg/kg dosing was not statistically different between groups (normal, overweight, and obese: 6.7, 6.4, and 6.7 mg/kg, respectively, P = 0.52). Median BMI of patients with therapeutic and subtherapeutic trough levels was similar at 19.9 kg/m² (interquartile range [IQR], 17.3-23.8) and 19.7 kg/m² (IQR, 17.4-21.9), respectively. BMI had no effect on secondary loss of response to infliximab, with no significant difference between normal and high BMI subgroups (13.4 vs. 16.7%, P = 0.9).

Conclusions

In a subgroup of pediatric IBD patients on maintenance infliximab, excess weight gain was not associated with higher weight-based dosing, lower serum trough levels, or increased risk of treatment failure.

Is obesity a predictor for lack of response to treatment in psoriatic arthritis? A systematic review

OBJECTIVES

To update the study of the association between obesity and treatment response in psoriatic arthritis.

METHODS

Updating a systematic review of clinical trials, prospective or retrospective longitudinal studies and case-control studies in psoriatic arthritis in which obesity was assessed as a predictor of efficacy or toxicity. Risks of bias were assessed with validated scales. A meta-analysis of the results of studies with similar outcome variables and weight measurements was performed.

RESULTS

Twenty-one studies were included (6 review of clinical trials, 6 longitudinal studies, 7 registers and one case-control studie), with moderate quality. The risk of achieving an ACR20 response if weight≥100kg was estimated at OR=1.42 (1-2.08) and that of withdrawing treatment in an OR of 1.60 (95% CI: 1.34 - 1.92).

CONCLUSIONS

There seems to be a greater risk of withdrawal of treatment due to inefficacy and difficulty in achieving remission in patients with psoriatic arthritis if they are obese.

Model-Based Therapeutic Drug Monitoring of Infliximab Using a Single Serum Trough Concentration

BACKGROUND AND OBJECTIVES

The pharmacokinetics of infliximab are highly variable and influence clinical response in chronic inflammatory diseases. The goal of this study was to build a Bayesian model allowing predictions of upcoming infliximab concentrations and dosing regimen adjustment, using only one concentration measurement and information regarding the last infliximab infusion.

METHODS

This retrospective study was based on data from 218 patients treated with infliximab in Tours University Hospital who were randomly assigned to learning (two-thirds) or validation (one-third) data subsets. One-compartment pharmacokinetic and time since last dose (TLD) models were built and compared using learning and validation subsets. From these models, Bayesian pharmacokinetic and TLD models using one concentration measurement (1C-PK and 1C-TLD) were designed. The predictive performances of the 1C-TLD model were tested on two external validation cohorts.

RESULTS

Pharmacokinetic and TLD models described the data satisfactorily and provided accurate parameter estimations. Comparable predictions of infliximab concentrations were obtained from pharmacokinetic versus TLD models, as well as from Bayesian 1C-PK versus 1C-TLD models. The 1C-TLD model showed satisfactory prediction of future infliximab concentrations and provided satisfactory predictions of infliximab steady-state concentration for up to three upcoming visits after a blood sample.

CONCLUSIONS

Accurate individual concentration predictions can be obtained using a single infliximab concentration measurement and information regarding only the last infusion. The 1C-TLD model may help to optimize the dosing regimen of infliximab in routine therapeutic drug monitoring.

Pharmacokinetic Similarity of ABP 710, a Proposed Biosimilar to Infliximab: Results From a Randomized, Single-Blind, Single-Dose, Parallel-Group Study in Healthy Subjects

This was a randomized, single‐blind, single‐dose, 3‐arm parallel‐group study. Healthy subjects were randomized to receive ABP 710 (n = 50) or infliximab reference product (RP) sourced from the United States (infliximab US; n = 50) or the European Union (infliximab EU; n = 50) 5 mg/kg intravenously over 2 hours. The primary endpoint was area under the serum concentration–time curve from time 0 extrapolated to infinity (AUC_inf) for the comparison of ABP 710 to infliximab US and infliximab EU. Secondary endpoints included safety, tolerability, and immunogenicity. AUC_inf was similar across the 3 groups, showing similarity of ABP 710 to infliximab RP as well as similarity of infliximab US with infliximab EU. Geometric mean ratio of AUC_inf was 0.89 between ABP 710 and infliximab US, 1.00 between ABP 710 and infliximab EU, and 1.11 between infliximab US and infliximab EU. All 90% confidence intervals of the geometric mean ratios were fully contained within the prespecified standard pharmacokinetic equivalence criteria range of 0.80 to 1.25. Treatment‐related adverse events were mild to moderate and reported for 83.7%, 86.0%, and 83.7% of subjects in the ABP 710, infliximab US, and infliximab EU treatment groups, respectively; incidence of antidrug antibody rates observed across the 3 groups were similar. Results of this study demonstrated pharmacokinetic similarity of ABP 710 with infliximab RP following a single 5‐mg/kg intravenous injection. The safety and tolerability of ABP 710 and infliximab RP were comparable. These results add to the totality of evidence providing further support that the proposed biosimilar ABP 710 is similar to infliximab RP. (Trial ID: ACTRN12614000903684.)

Clinical Pharmacokinetics and Pharmacodynamics of Infliximab in the Treatment of Inflammatory Bowel Disease

Infliximab was the first monoclonal antibody to be approved for the treatment of pediatric and adult patients with moderately to severely active Crohn's disease (CD) and ulcerative colitis (UC). It has been shown to induce and maintain both clinical remission and mucosal healing in pediatric and adult patients with inflammatory bowel disease (IBD) who are unresponsive or refractory to conventional therapies. The administration of infliximab is weight-based and the drug is administered intravenously. The volume of distribution of infliximab is low and at steady state ranges from 4.5 to 6 L. Therapeutic monoclonal antibodies, such as immunoglobulins, are cleared from the circulation primarily by catabolism. Median infliximab half-life is approximately 14 days. Infliximab concentration-time data in patients with CD and UC have been shown to be highly variable within an individual patient over time and between individuals by multiple population pharmacokinetic models. Covariates that have been identified to account for a part of the observed inter- and intra-individual variability in clearance are the presence of antidrug antibodies, use of concomitant immunomodulators, degree of systemic inflammation, serum albumin concentration, and body weight, which can affect the pharmacodynamic response. This article provides a comprehensive review of the clinical pharmacokinetics and pharmacodynamics of infliximab, as well as the role of therapeutic drug monitoring in the treatment of IBD.

Therapeutic drug monitoring of infliximab in spondyloarthritis. A review of the literature

Available evidence indicates that a therapeutic drug monitoring strategy leads to major cost savings related to the anti-tumour necrosis factor-α therapy in both inflammatory bowel disease and rheumatoid arthritis (RA) patients, with no negative impact on efficacy. However, although the systematic use of therapeutic drug monitoring could potentially be beneficial and economically acceptable to drug dose optimization, it is not justifiable for all drugs. Infliximab (IFX) is a chimeric monoclonal immunoglobulin G1 targeting tumour necrosis factor. It has been approved for the treatment of immuno-inflammatory diseases, including RA, ankylosing spondylitis, psoriatic arthritis, Crohn's disease and ulcerative colitis. IFX's pharmacokinetics is highly variable and influences clinical response in chronic inflammatory diseases. Clinical response increases with IFX trough concentrations in RA, ankylosing spondylitis, inflammatory bowel disease and psoriatic patients. Target concentrations predictive of good clinical response were proposed in RA, Crohn's disease and ulcerative colitis. The purpose of this article is to review the current literature surrounding IFX serum concentrations and their related parameters with disease activity in patients with spondyloarthritis. Gathering information about the efficacy of IFX in patients with spondyloarthritis and relating IFX serum concentrations to disease activity were the main goals of this study.

Optimising infliximab induction dosing for patients with ulcerative colitis

AIMS

The therapeutic failure of infliximab therapy in patients with ulcerative colitis remains a challenge even 2 decades after its approval. Therapeutic drug monitoring (TDM) has shown value during maintenance therapy, but induction therapy has still not been explored. Patients may be primary nonresponders or underexposed with the standard dosing regimen. We aimed to: (i) develop a population pharmacokinetic-pharmacodynamic model; (ii) identify the best exposure metric that predicts mucosal healing; and (iii) build an exposure-response (ER) model to demonstrate model-based dose finding during induction therapy with infliximab.

METHODS

Data were retrospectively collected from a clinical database. A total of 583 samples, from 204 patients, was used to develop a population pharmacokinetic model to generate exposure metrics for subsequent ER modelling. A subset of 159 patients was used to develop a logistic regression ER model, describing the relationship between infliximab exposure and ordered transitions between Mayo endoscopic subscore (MES) 3, 2 and ≤1 (baseline to post-induction).

RESULTS

A 1-compartment population pharmacokinetic model with interindividual and interoccasion variability was found to fit the data best. Covariates influencing exposure were C-reactive protein, albumin, baseline MES, fat-free mass, concomitant corticosteroid use and pancolitis. The cumulative area under the infliximab concentration-time curve until endoscopy (CAUC_endoscopy ) was found to be the best exposure metric for predicting mucosal healing (baseline MES >1 and post-induction MES ≤1). The model predicted that 70% of patients will attain mucosal healing with infliximab administered at days 0, 14 and 42 and a target CAUC_endoscopy of 3752 mg/L*day at day 84.

CONCLUSIONS

TDM-based dose individualisation targeting CAUC_endoscopy has the potential to improve the effectiveness of infliximab during induction therapy.

Pharmacokinetic Effects of Antidrug Antibodies Occurring in Healthy Subjects After a Single Dose of Intravenous Infliximab

Background

Infliximab pharmacokinetic studies have been performed in patients receiving chronic infliximab therapy. In these patients, infliximab antidrug antibodies (ADAs) increase infliximab clearance and decrease serum levels and drug efficacy.

Objective

This study analyzed the pharmacokinetic effect of infliximab ADAs in healthy subjects receiving a single dose of intravenous infliximab.

Methods

Data were obtained from a single-blind, parallel-group, single-dose study of healthy subjects receiving 5 mg/kg of intravenous SB2 (infliximab biosimilar), EU-sourced Remicade (EU-IFX) or US-sourced Remicade (US-IFX). Serum infliximab was measured at 1, 2, 3, 6, 12, 24, 48, and 72 h and at 5, 7, 14, 21, 28, 42, 56, and 70 days after administration. ADAs were measured pre-dose and at 29 and 71 days. Data from the first ten subjects randomized to each treatment arm were utilized for this study. A two-compartment model of the serum infliximab vs. time curve was developed using nonlinear regression.

Results

At 10 weeks, 11 subjects (37%) developed ADAs. ADAs were detected in four subjects after SB2, one subject after EU-IFX, and six subjects after US-IFX infusion. Of these, neutralizing antibodies occurred in one subject after SB2, in no subjects after EU-IFX, and in three subjects after US-IFX infusion. Infliximab clearance was increased in subjects with ADAs vs. those without ADAs (12.89 ± 2.69 vs. 9.90 ± 1.74 ml/h; p < 0.0005). The elimination half-time was shorter in subjects with ADAs (282.4 ± 56.4 vs. 343.3 ± 61.9 h; p < 0.01). Serum infliximab measured at 8 weeks correlated closely with infliximab clearance (R² = 0.5494; p < 0.0001).

Conclusion

ADAs are common in healthy subjects after a single intravenous dose of infliximab and result in faster infliximab clearance, shorter elimination time, and lower serum infliximab levels. These data confirm that ADAs are common with biologic therapy and significantly impact the efficacy of these drugs.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-017-0211-y) contains supplementary material, which is available to authorized users.

Obesity and Response to Infliximab in Patients with Inflammatory Bowel Diseases: Pooled Analysis of Individual Participant Data from Clinical Trials

OBJECTIVES

To assess whether obesity may affect response to infliximab, we conducted an individual participant data pooled analysis using data from clinical trials of infliximab in inflammatory bowel diseases (IBD), using the Yale Open Data Access (YODA) Project.

METHODS

We analyzed individual participant data from four clinical trials of infliximab in adults with IBD (ACCENT-I, SONIC, ACT-1, and -2). Patients were categorized as obese (body mass index [BMI] ≥ 30 kg/m²) vs. non-obese, and by quartiles based on BMI or weight at time of trial entry. Primary outcome was clinical remission (Crohn's disease activity index [CDAI] < 150 or pediatric CDAI <10, Mayo Clinic Score <3); secondary outcomes were clinical response and mucosal healing. Multivariable logistic regression analysis was performed, after adjusting for sex, smoking, disease activity, and concomitant prednisone and/or immunomodulators.

RESULTS

We included 1205 infliximab-treated patients (mean age 37 years, 51.6% males, 14% obese). Obesity was not associated with odds of achieving clinical remission (obese vs. non-obese: adjusted OR, 0.93 [95% CI, 0.47-1.46]; Q4 vs. Q1: aOR, 0.94 [0.61-1.47], p-value for trend = 0.97), clinical response (Q4 vs. Q1: aOR, 0.84 [0.52-1.35], p = 0.45) or mucosal healing (Q4 vs. Q1: aOR, 1.13 [0.55-2.34], p = 0.95). These results were consistent across strata based on disease type (Crohn's disease and ulcerative colitis) and trial design (induction and maintenance therapy).

CONCLUSIONS

Based on individual participant data pooled analysis, obesity is not associated with inferior response to infliximab in patients with IBD. Future studies examining the association between obesity and fixed-dose therapies are warranted.

Obesity and response to anti-tumor necrosis factor-α agents in patients with select immune-mediated inflammatory diseases: A systematic review and meta-analysis

OBJECTIVES

We sought to evaluate the association between obesity and response to anti-tumor necrosis factor-α (TNF) agents, through a systematic review and meta-analysis.

METHODS

Through a systematic search through January 24, 2017, we identified randomized controlled trials (RCTs) or observational studies in adults with select immune-mediated inflammatory diseases-inflammatory bowel diseases (IBD), rheumatoid arthritis (RA), spondyloarthropathies (SpA), psoriasis and psoriatic arthritis (PsA)-treated with anti-TNF agents, and reporting outcomes, stratified by body mass index (BMI) categories or weight. Primary outcome was failure to achieve clinical remission or response or treatment modification. We performed random effects meta-analysis and estimated odds ratios (OR) and 95% confidence interval (CI).

RESULTS

Based on 54 cohorts including 19,372 patients (23% obese), patients with obesity had 60% higher odds of failing therapy (OR,1.60; 95% CI,1.39-1.83;I2 = 71%). Dose-response relationship was observed (obese vs. normal BMI: OR,1.87 [1.39-2.52]; overweight vs. normal BMI: OR,1.38 [1.11-1.74],p = 0.11); a 1kg/m2 increase in BMI was associated with 6.5% higher odds of failure (OR,1.065 [1.043-1.087]). These effects were observed across patients with rheumatic diseases, but not observed in patients with IBD. Effect was consistent based on dosing regimen/route, study design, exposure definition, and outcome measures. Less than 10% eligible RCTs reported outcomes stratified by BMI.

CONCLUSIONS

Obesity is an under-reported predictor of inferior response to anti-TNF agents in patients with select immune-mediated inflammatory diseases. A thorough evaluation of obesity as an effect modifier in clinical trials is warranted, and intentional weight loss may serve as adjunctive treatment in patients with obesity failing anti-TNF therapy.