Brief Report: Relationship Between Serum Infliximab Concentrations and Risk of Infections in Patients Treated for Spondyloarthritis

Precision Dosing of Intravenous Tocilizumab: Development of Pharmacokinetic Model-Derived Tapering Strategies for Patients With Rheumatoid Arthritis

BACKGROUND

Tocilizumab targets the interleukin-6 receptor, and dosing is complex owing to its nonlinear clearance related to target binding. Therefore, tapering tocilizumab requires a different approach than that of tumor necrosis factor inhibitors (TNFi). This study aimed to identify these differences and enable personalized treatment of rheumatoid arthritis (RA) beyond TNFi therapy.

METHODS

A population pharmacokinetic model of intravenous tocilizumab was developed using data from a randomized controlled trial of dose tapering in patients with RA. Subsequent population-level Monte Carlo and individual Bayesian simulations were performed to create tapering strategies involving dose reduction and interval extension. The target trough concentration of tocilizumab was 5 mg/L. Finally, the drug savings were compared between the 2 methods.

RESULTS

The pharmacokinetic of tocilizumab was described with a 2-compartment model with parallel linear (CL 0.20 L/d) and nonlinear (V M 5.2 mg/d, K M 0.19 mg/L) elimination. The linear clearance rate and central volume of distribution increased with lean body mass, and men exhibited higher clearance rates than women. The simulated concentration-time profiles demonstrated that, owing to nonlinear clearance, drug concentrations decreased more than dose-proportionally with lower doses. Tapering based on an individual Bayesian approach emerged as the most promising strategy, yielding a 39% reduction in drug use across virtual populations.

CONCLUSIONS

Tapering strategies were developed for intravenous tocilizumab, offering potential application in patients with RA who have reached low disease activity or remission, pending clinical validation. The developed strategies demonstrate that the tapering of tocilizumab should be approached more carefully and in smaller steps than that of TNFi.

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.

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.

Physiologically-Based Pharmacokinetic Modeling of Anti-Tumor Necrosis Factor Agents for Inflammatory Bowel Disease Patients to Predict the Withdrawal Time in Pregnancy and Vaccine Time in Infants

Anti-tumor necrosis factor (anti-TNF) agents are widely applied for patients with inflammatory bowel disease (IBD); however, the timing of the last dosing for IBD pregnancy and time to elimination in anti-TNF agent-exposed infants is controversial. This study aimed to determine the optimal timing for the last dosing of anti-TNF agents (infliximab, adalimumab, and golimumab) in pregnant women with IBD, as well as to investigate the recommended vaccine schedules for infants exposed to these drugs. A physiologically-based pharmacokinetic (PBPK) model of anti-TNF agents was built for adults and extrapolated to pregnant patients, fetuses, and infants. The PBPK models successfully predicted and verified the pharmacokinetics (PKs) of infliximab, adalimumab, and golimumab in pregnancy, fetuses, and infants. The predicted PK data were within two-fold of the observed data. The simulated results were used as timing advice. According to the dose of administration, the suggested timing of the last dosing for infliximab, adalimumab, and golimumab is successfully provided based on PBPK predictions. PBPK models indicated that, for infants, the advocated timing of vaccination is 12, 8, and 5 months after birth for infliximab, adalimumab, and golimumab, respectively. Our study illustrated that PBPK models can provide a valuable tool to predict the PKs of large macromolecules in pregnant women, fetuses, and infants, ultimately informing drug-treatment decisions for pregnancy and vaccination regimens for infants.

EULAR points to consider for therapeutic drug monitoring of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases

OBJECTIVE

To develop EULAR points-to-consider for therapeutic drug monitoring (TDM) of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases (RMDs).

METHODS

The points-to-consider were developed in accordance with EULAR standardised operation procedures by a multidisciplinary task force from eight European countries, based on a systematic literature review and expert consensus. Level of evidence and strength of the points-to-consider were determined, and mean levels of agreement among the task force were calculated using a 10-point rating scale.

RESULTS

Six overarching principles and 13 points-to-consider were formulated. The level of agreement among the task force for the overarching principles and points-to-consider ranged from 8.4 to 9.9.The overarching principles define TDM and its subtypes, and reinforce the underlying pharmacokinetic/pharmacodynamic principles, which are relevant to all biopharmaceutical classes. The points-to-consider highlight the clinical utility of the measurement and interpretation of biopharmaceutical blood concentrations and antidrug antibodies in specific clinical scenarios, including factors that influence these parameters. In general, proactive use of TDM is not recommended but reactive TDM could be considered in certain clinical situations. An important factor limiting wider adoption of TDM is the lack of both high quality trials addressing effectiveness and safety of TDM and robust economic evaluation in patients with RMDs. Future research should focus on providing this evidence, as well as on further understanding of pharmacokinetic and pharmacodynamic characteristics of biopharmaceuticals.

CONCLUSION

These points-to-consider are evidence-based and consensus-based statements for the use of TDM of biopharmaceuticals in inflammatory RMDs, addressing the clinical utility of TDM.

Therapeutic drug monitoring of biopharmaceuticals in inflammatory rheumatic and musculoskeletal disease: a systematic literature review informing EULAR points to consider

The objectives of this review were to collect and summarise evidence on therapeutic drug monitoring (TDM) of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases and to inform the EULAR Task Force for the formulation of evidence-based points to consider. A systematic literature review (SLR) was performed, covering technical aspects and (clinical) utility of TDM, to answer 13 research questions. MEDLINE, Embase and Cochrane were searched until July 2020. American College of Rheumatology and EULAR abstracts were also considered for inclusion. Data were extracted in evidence tables and risk of bias assessment was performed. For the search on technical aspects, 678 records were identified, of which 22 papers were selected. For the clinical utility search, 3846 records were identified, of which 108 papers were included. Patient-related factors associated with biopharmaceutical blood concentrations included body weight, methotrexate comedication and disease activity. The identification of a target range was hampered by study variability, mainly disease activity measures and study type. Evidence was inconsistent for multiple clinical situations in which TDM is currently applied. However, for some particular scenarios, including prediction of future treatment response, non-response to treatment, tapering and hypersensitivity reactions, robust evidence was found. There is currently no evidence for routine use of proactive TDM, in part because published cost-effectiveness analyses do not incorporate the current landscape of biopharmaceutical costs and usage. This SLR yields evidence in favour of TDM of biopharmaceuticals in some clinical scenarios, but evidence is insufficient to support implementation of routine use of TDM.

Risk of nonpulmonary infections requiring hospitalization in spondyloarthritis

Objectives

To compare the risk of five nonpulmonary infections leading to hospitalization between spondyloarthritis (SpA) and nonspecific back pain (NSBP), and to identify the risk factors.

Methods

A total of 3018 patients with SpA and 2527 patients with NSBP were identified. Data from December 1995 to June 2019 was retrieved from a centralized electronic medical record system. The date of onset of five types of nonpulmonary infections including: urinary tract infection (UTI), skin infection, gastroenteritis (GE), septic arthritis, and pancreato‐hepatobiliary tract infection were identified. Demographic data, comorbidities, and medications used were also retrieved. Comparative risk of each type of infection between SpA and NSBP was determined using propensity score adjustment method. Cox regression model was used to identified risk factors.

Results

Patients with SpA were younger in age, predominantly male, with fewer comorbid diabetes mellitus (DM), renal impairment, and depression. Compared with NSBP, patients with SpA had higher risk of UTI (hazard ratio [HR] 1.91; p < .001), skin infection (HR 1.79; p < .001), and septic arthritis (HR 4.57; p = .04). Risk of GE (HR 1.42; p = 1.00), and pancreato‐hepatobiliary tract infection (HR 1.67; p = .06) were not increased. Infliximab was an independent risk factor for UTI (HR 2.21; p = .04). Duration of steroid therapy >6 months (HR 2.22; p < .001), smoker (HR 1.81; p < .001), and psoriasis (HR 2.47; p < .001) were risk factors for skin infection.

Conclusion

SpA was associated with increased risk of UTI, skin infection, and septic arthritis. Infliximab, prolonged steroid therapy, smoking, and psoriasis were associated risk factors.

Research Progress on Quantification Methods of Drug Concentration of Monoclonal Antibodies

Background:

With the development of monoclonal antibodies (mAbs) from the first generation of mice to the fourth generation of human origin, the efficacy and safety in the treatment of many diseases have been continuously improved. MAbs have been widely used in the treatment of cancer, chronic inflammatory diseases, and so on. However, the treatment response of mAbs varies greatly among individuals, and drug exposure may be affected by a variety of physiological and pathological factors, such as combined use of drugs and progression of disease. Therefore, studies tend to recommend therapeutic drug monitoring and individualized treatment strategies.

Objective:

In this paper, the commonly used methods of quantification of monoclonal antibodies were reviewed, especially liquid chromatography- mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA), to provide technical support for therapeutic drug detection and individualize dosing for patients.

Conclusion:

For patients achieving mAbs treatment, it is necessary to carry out therapeutic drug monitoring and take it as a routine monitoring index. We recommend that for pharmaceutical laboratories in hospitals, establishing an appropriate assay formats, such as ELISA and LC-MS/MS is critical to determine drug concentration and antidrug antibody (ADA) for mAbs.

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

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

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.

Cumulative Exposure to Infliximab, But Not Trough Concentrations, Correlates With Rate of Infection

BACKGROUND & AIMS

Infliximab increases the risk of infection in patients with inflammatory bowel diseases (IBD), but there is controversy over the relationship between drug concentration and infections. We aimed to assess factors associated with infection in infliximab-treated patients, including pharmacokinetic features.

METHODS

We collected data from 209 patients with IBD (102 men; mean age, 39 y; 159 with Crohn's disease; 54 received combination therapy) who received an infliximab maintenance regimen from November 2016 through April 2017 in France. Data were collected from each infusion visit (total of 640 infusions). Infliximab exposure was estimated based on the area under the curve (AUC) of drug concentration in pharmacokinetic models; individual exposures over the 6-month period were estimated based on the sum of the AUC (ΣAUC).

RESULTS

The mean infliximab trough level was 5.46 mg/L, and the mean ΣAUC was 3938 ± 1427 mg.d/L. A total of 215 infections were collected from the 640 infusion visits; 123 patients (59%) had at least 1 infection. Factors independently associated with infection after multivariate analysis were smoking (odds ratio [OR], 2.05; P = .046), IBD flare (OR, 2.71; P = .006), and a high ΣAUC of infliximab (above 3234 mg x d/L) (OR, 2.02; P = .02). The ΣAUC was higher in patients with an occurrence of infection (P = .04) and correlated with the number of infections (P = .04). Trough concentration of infliximab alone was not associated with infection.

CONCLUSIONS

Almost two-thirds of patients treated with infliximab developed an infection; risk was individually correlated with cumulative increase in drug exposure, but not infliximab trough level.

[Rheumatology, the multitude of options]

The number of therapeutic antibodies available in rheumatology increases every year, mainly indicated in chronic inflammatory rheumatisms and other immune-mediated inflammatory diseases. The choice between all these monoclonal antibodies depends on their specificities, patients and diseases characteristics. Until now, there is no reliable biomarker, predictive of response for specialized medicine purpose. Today, therapeutic drug monitoring and anti-drug antibodies testing can help to better adapt the dose of the drug and to help in the decision to switch to another biological drug according to the activity of the inflammatory disease.

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.

Therapeutic drug monitoring in inflammatory bowel disease: for every patient and every drug?

PURPOSE OF REVIEW

The current review provides an updated overview on the role of therapeutic drug monitoring (TDM) of biological therapies in inflammatory bowel disease (IBD). We examine the data behind TDM for the antitumor necrosis factor agents, vedolizumab and ustekinumab, in patients with IBD. In addition, we discuss reactive vs. proactive TDM.

RECENT FINDINGS

There is a positive correlation between biologic drug concentrations and favorable therapeutic outcomes in IBD, although the majority of data refer to antitumor necrosis factor therapy. Reactive TDM has rationalized the management of patients with IBD with loss of response to biological therapy. Moreover, reactive TDM of infliximab has been proven to be more cost-effective when compared with empiric dose optimization. Preliminary data suggest that proactive TDM of infliximab and adalimumab applied in patients with clinical response/remission is associated with better therapeutic outcomes compared with standard of care (empiric treatment and/or reactive TDM).

SUMMARY

For all biologics in IBD, there is a positive correlation between drug concentrations and favorable therapeutic outcomes. Reactive TDM is the new standard of care for optimizing biologic therapies in IBD, whereas recent data suggest an important role of proactive TDM for optimizing antitumor necrosis factor therapy in IBD.

Higher adalimumab serum levels do not increase the risk of adverse events in patients with inflammatory bowel disease

Background: The relationship between serum adalimumab concentrations and adverse events in patients with inflammatory bowel disease (IBD) is unknown. We aimed to determine whether patients with IBD using adalimumab are at increased risk of adverse events if they have higher adalimumab serum levels compared to those with lower adalimumab levels. Methods: This was a retrospective study of 191 IBD patients with at least one serum adalimumab level measurement available. The cohort was divided using a cutoff level of 10 mcg/mL. The primary outcome was the rate of overall adverse events between the two groups. Secondary outcomes included rate of infections, dermatologic reactions, injection-site reactions and other adverse events in both groups. Rates of discontinuation of adalimumab due to adverse events were evaluated. Multivariate logistic regression analysis was performed to evaluate the relationship between adalimumab levels and adverse events. Results: A total of 41 adverse events were reported in 191 patients in the overall cohort. Among 86 patients with higher adalimumab levels, 22 adverse events were reported, vs. 19 adverse events among 105 patients with lower adalimumab levels (25.6% vs. 18.1%, p = .21). Analysis according to adalimumab level tertiles also did not show significant differences in the rates of adverse events. A multivariate forward selection model also did not find higher odds of an adverse event in IBD patients with higher adalimumab levels compared to lower levels (OR 1.54, 95% CI 0.77-3.08). Conclusions: There does not appear to be a relationship between adalimumab exposure and risk of adverse events in IBD patients.

Predictors of relapse following infliximab de-escalation in patients with inflammatory bowel disease: the value of a strategy based on therapeutic drug monitoring

BACKGROUND

There are limited data concerning infliximab drug monitoring during de-escalation of the treatment of inflammatory bowel disease (IBD).

AIM

To define the rate and the predictors of relapse following infliximab de-escalation in IBD patients in remission.

METHODS

All IBD patients at a single referral centre in clinical and biological remission and in whom the dose of infliximab had been de-escalated were included. Patients in remission with a high trough level of infliximab (>7 mg/L) were considered to be trough level-based de-escalation patients. The data were retrieved from a prospective IBD database. Actuarial analysis was performed for statistical purposes.

RESULTS

A total of 146 de-escalations were performed in 96 patients (Crohn's disease/ulcerative colitis: 68%/32%); 54 (37%) were based on clinical remission only, and 92 (63%) were based on clinical remission associated with a trough level above 7 mg/L. The cumulative probabilities of relapse following infliximab de-escalation were 16% and 47% at 1 and 2 years, respectively. Ulcerative colitis was associated with an increased risk of relapse (HR = 3.2, P = 0.005). Conversely, combination therapy at infliximab initiation (HR = 0.39, P = 0.0110) and trough level-based de-escalation were associated with decreased risk of relapse (HR = 0.45, P = 0.024). Trough levels before and after de-escalation were well correlated; a decrease by half was observed following a 2-week interval increase or a half-dose decrease.

CONCLUSION

The use of trough levels to assess the feasibility of dose de-escalation seems to be a prerequisite for decreasing the risk of relapse.

Pharmacokinetics of rituximab and clinical outcomes in patients with anti-neutrophil cytoplasmic antibody associated vasculitis

Objectives

To study the determinants of the pharmacokinetics (PK) of rituximab (RTX) in patients with ANCA-associated vasculitis (AAV) and its association with clinical outcomes.

Methods

This study included data from 89 patients from the RTX in AAV trial who received the full dose of RTX (four weekly infusions of 375 mg/m2). RTX was quantified at weeks 2, 4, 8, 16 and 24, and summarized by computing the trapezoidal area under the curve. We explored potential determinants of the PK-RTX, and analysed its association with clinical outcomes: achievement of remission at 6 months, duration of B-cell depletion and time to relapse in patients who achieved complete remission.

Results

RTX serum levels were significantly lower in males and in newly diagnosed patients, and negatively correlated with body surface area, baseline B-cell count and degree of disease activity. In multivariate analyses, the main determinants of PK-RTX were sex and new diagnosis. Patients reaching complete remission at month 6 had similar RTX levels compared with patients who did not reach complete remission. Patients with higher RTX levels generally experienced longer B-cell depletion than patients with lower levels, but RTX levels at the different time points and area under the curve were not associated with time to relapse.

Conclusion

Despite the body-surface-area-based dosing protocol, PK-RTX is highly variable among patients with AAV, its main determinants being sex and newly diagnosed disease. We did not observe any relevant association between PK-RTX and clinical outcomes. The monitoring of serum RTX levels does not seem clinically useful in AAV.

Successful reduction of overexposure in patients with rheumatoid arthritis with high serum adalimumab concentrations: an open-label, non-inferiority, randomised clinical trial

OBJECTIVE

High adalimumab serum concentrations do not result in better response in patients with rheumatoid arthritis (RA), suggesting overexposure. We investigated whether patients with adalimumab concentrations >8 µg/mL can prolong their dosing interval by 50% without a clinically relevant change in disease activity.

METHODS

Consecutive patients with RA, treated with adalimumab 40 mg every other week for at least 28 weeks, were approached for this randomised, open-label, non-inferiority trial. Patients with adalimumab trough concentrations >8 µg/mL were randomly (1:1) assigned to dose-interval prolongation of once every 3 weeks or continuation of every other week. Primary outcome was the change in disease activity score of 28 joints (ΔDAS28-ESR) after 28 weeks, with a non-inferiority margin of 0.6 points.

RESULTS

In total, 147 patients were screened. Fifty-five patients had concentrations >8 µg/mL and were randomised. Mean ΔDAS28 after 28 weeks was -0.14±SD 0.61 in the prolongation group and 0.30±0.52 in the continuation group. Mean difference was significantly in favour of the prolongation group: 0.44 (95% CI 0.12 to 0.76, p=0.01).

CONCLUSIONS

Adalimumab-treated patients with RA with trough concentrations >8 µg/mL can prolong their standard dosing interval to once every 3 weeks without loss of disease control.

TRIAL REGISTRATION NUMBER

NTR3509; Results.

Biologic-Induced Infections in Inflammatory Bowel Disease: The TNF-α Antagonists

Objective: To review the mechanism and association of infectious risk among the tumor-necrosis factor α (TNF-α) antagonists used in inflammatory bowel disease. Data Sources: A PubMed literature search was performed using the following search terms: infliximab, adalimumab, certolizumab, golimumab, inflammatory bowel disease, crohn’s, ulcerative colitis, adverse effects, adverse events, safety, and infection. Study Selection and Data Extraction: Meta-analyses and cohort studies with outcomes pertaining to quantitative infectious risk were reviewed. Case reports and case series describing association between TNF-α inhibitors and infection were also reviewed. Data Synthesis: A total of 7 recent meta-analyses of randomized trials demonstrate inconclusive association of infection with TNF-α antagonists. Registry data suggest that medications carry an independent risk of opportunistic infections. Risk factors for infection include older age, malnutrition, diabetes, and possibly combination therapy. Reported infections vary widely but include intracellular and granulomatous bacteria, viruses, and fungi. Conclusion: TNF-α antagonists are associated with an increased risk of opportunistic infection, although this risk has not been demonstrated conclusively in randomized controlled trials. Knowledge of concomitant risk factors, mechanism of infectious risk, and available treatment options can improve patient care in the clinical setting.

Therapeutic Drug Monitoring During Induction of Anti-Tumor Necrosis Factor Therapy in Inflammatory Bowel Disease: Defining a Therapeutic Drug Window

Anti-tumor necrosis factor (TNF) therapy has revolutionized the treatment of inflammatory bowel disease (IBD). However, up to 30% of patients with IBD show no clinical benefit and are defined as having a primary nonresponse. Primary nonresponse to a biologic can be attributed to either pharmacokinetic or pharmacodynamic issues, such as those involved in secondary loss of response. Pharmacokinetic issues are linked to undetectable or subtherapeutic drug concentrations because of either an accelerated non-immune-mediated clearance or immunogenicity and the development of antidrug antibodies, whereas pharmacodynamic issues are likely related to "non-TNF driven" disease. Therapeutic drug monitoring (TDM), defined as the evaluation of drug concentrations and antidrug antibodies, has been proven effective for optimizing anti-TNF therapy in IBD. Nevertheless, most of the data for TDM relate to patients losing response during maintenance therapy, whereas much less is known about the therapeutic drug window and use of TDM during anti-TNF induction therapy. Recent exposure-response relationship studies, though, demonstrate that high serum anti-TNF drug concentrations during and early after induction therapy are associated with favorable therapeutic outcomes in IBD. This suggests that early optimization of anti-TNF therapy may prevent some of the primary nonresponse related to pharmacokinetic issues (low drug concentrations) and lead to better short- and long-term outcomes. This review will focus on the role of TDM during the induction phase of anti-TNF therapy.

Editorial: therapeutic de-escalation of anti-tumour necrosis factor therapy - is less enough?

Linked Content

This article is linked to Pariente and Laharie paper. To view this article visit https://doi.org/10.1111/apt.12838.