Infliximab concentration monitoring improves the control of disease activity in rheumatoid arthritis

Efficacy, safety, and cost-effectiveness of therapeutic drug monitoring (TDM) for TNF inhibitor therapy in rheumatic disease: A systematic review and meta-analysis

OBJECTIVE

The benefits of TDM-guided TNFi therapy in patients with rheumatic disease was still controversial. This systematic review and meta-analysis was conducted to explore if the TDM-guided TNFi therapy is superior to empirical-guided therapy.

METHODS

We systematically searched PubMed, Web of Science, Cochrane Library, and EMBASE databases for articles published between database inception and October 05, 2023. Studies reporting endpoints in TDM-guided TNFi therapy and empirical therapy were included. Results would be presented in risk ratio (RR) and mean difference, with 95 % confidence interval (CI) reported. This study is registered with PROSPERO (CRD42022353956).

RESULTS

A total of 14 studies (eight RCTs and six cohort studies) involving 2427 patients were included in this meta-analysis. In the scenario of response prediction, compared with empirical-guided therapy, TDM-guided TNFi therapy had association with higher treat-to-target rates (RR 1.30, 95 % CI 1.02-1.65, P=0.03, I2=79 %), more specifically, higher low disease activity rates (RR 2.11, 95 % CI 1.22-3.66, P=0.007, I2=61 %), but no difference in clinical remission rates (RR 0.98,95 % CI 0.87-1.11, P=0.75, I2=0 %). In the scenario of dose reduction prediction, lower relapse rates (RR 0.73, 95 % CI 0.65-0.82, P <0.00001, I2=0 %) were observed compared with empirical-guided dose reduction strategy, but no difference (RR 1.24, 95 % CI 0.85-1.80, P=0.27, I2=57 %) between TDM-guided dose reduction and standard-dosing therapy. No significant difference was observed in change of disease activity score, mean disease activity score, radiographic progression, and safety. And TDM-guided therapy was associated with reduced cost per patient per year calculated as the total accumulated sum of therapy cost.

CONCLUSION

TDM-guided TNFi therapy was associated with increased rates of low disease activity and decreased risks of relapse, and may save cost compared with empirical-guided therapy in patients with rheumatic disease. But this does not mean that the use of TDM-guided TNFi therapy can be advocated, because there is no difference in clinical remission rates and many other outcomes. More researches, especially randomized clinical trials are needed to verify this conclusion in the future.

A Rapid Method for Direct Quantification of Antibody Binding-Site Concentration in Serum

The quantitation of the available antibody binding-site concentration of polyclonal antibodies in serum is critical in defining the efficacy of vaccines against substances of abuse. We have conceptualized an equilibrium dialysis (ED)-based approach coupled with fluorimetry (ED-fluorimetry) to measure the antibody binding-site concentration to the ligand in an aqueous environment. The measured binding-site concentrations in monoclonal antibody (mAb) and sera samples from TT-6-AmHap-immunized rats by ED-fluorimetry are in agreement with those determined by a more established equilibrium dialysis coupled with ultraperformance liquid chromatography tandem mass spectrometry (ED-UPLC-MS/MS). Importantly, we have shown that the measured antibody binding-site concentrations to the ligand by ED-fluorimetry were not influenced by the sample serum matrix; thus, this method is valid for determining the binding-site concentration of polyclonal antibodies in sera samples. Further, we have demonstrated that under appropriate analytical conditions, this method resolved the total binding-site concentrations on a nanomolar scale with good accuracy and repeatability within the microliter sample volumes. This simple, rapid, and sample preparation-free approach has the potential to reliably perform quantitative antibody binding-site screening in serum and other more complex biological fluids.

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.

Potential application of measuring serum infliximab levels in rheumatoid arthritis management: A retrospective study based on KURAMA cohort data

Infliximab (IFX) therapy has considerably improved the treatment of rheumatoid arthritis (RA). However, some patients still do not respond adequately to IFX therapy, or the efficacy of the treatment diminishes over time. Although previous studies have reported a relationship between serum IFX levels and therapeutic efficacy, the potential applications of IFX therapeutic drug monitoring (TDM) in clinical practice remain unclear. The purpose of this study was to investigate the potential applications of IFX TDM by analyzing a Japanese cohort database. Data were collected retrospectively from the Kyoto University Rheumatoid Arthritis Management Alliance cohort between January 1, 2011, and December 31, 2018. Serum IFX levels were measured using a liquid chromatography-tandem mass spectrometer. Out of the 311 RA patients that used IFX, 41 were eligible for the analysis. Serum IFX levels were significantly higher in responders than in non-responders. An optimal cut-off value was determined to be 0.32 μg/mL based on a receiver operating characteristic curve. At the IFX measurement point, a better therapeutic response was observed in the high IFX group (n = 32) than in the low IFX group (n = 9). Conversely, at the maximum effect point, when DAS28-ESR was the lowest between IFX introduction and measurement points, there were no differences in responder proportions between the low and high IFX groups. IFX primary ineffectiveness could be avoided with appropriate dose escalation without blood concentration measurement in clinical practice. In conclusion, IFX TDM could facilitate the identification of secondary non-responders and in turn, proper IFX use.

Structure-Indicated LC-MS/MS Bioanalysis of Therapeutic Antibodies

Monoclonal antibodies bind to Protein A/G resin with 100 nm-diameter pores, which orients the Fab toward the reaction solution. Then, they can be proteolyzed using trypsin immobilized on the surface of 200 nm-diameter nanoparticles. The difference between the two particle diameters allows Fab-selective proteolysis by limiting trypsin access to the antibody substrate. The specific signature peptide of monoclonal antibody is collected, which comprises the complementarity-determining regions (CDRs). Excess trypsin protease and peptide fragments from common sequences in Fc that inhibit the analysis can then be separated and removed. The resulting peptide samples are separated through high performance liquid chromatography on a 20 nm-diameter pore-size reversed-phase C18 column. These are then sequentially ionized with an electrospray interface and subjected to mass spectrometry (MS). In MS, peptide ions are trapped and fragment ions are generated by the collision-induced dissociation with argon gas. These are detected with multiple reaction monitoring measurements to perform a highly sensitive and accurate quantitative analysis.By focusing on various physicochemical features at each analytical scene, such as characteristic structure and orientation of antibody, control of trypsin reaction field, carry-over on HPLC column, ionization suppression effect from endogenous proteins, and detection of amino acid sequence specificity of antibody, we optimized the overall conditions from the sample processing up to MS detection and developed analytical validation and clinical application of many therapeutic antibodies using our Fab-selective proteolysis technology that is based on the structure-indicated approach.

Viability of a Serum Infliximab Concentration-Detecting Reagent as a Qualitative Assay for an Infliximab Biosimilar

The efficacy of infliximab in treating rheumatoid arthritis depends on its serum trough concentration, which must be maintained at a minimum of 1 µg/mL to achieve the desired effects. However, Japan's National Health Insurance system does not cover tests for rheumatoid arthritis patients undergoing treatment with biosimilar infliximab because its performance as a biosimilar remains unclear. This study aimed to investigate whether the Remi-check Q qualitative assay yields comparable results for biosimilar infliximab and the originator product. Infliximab BS 100 "NK" and Remicade 100^® were separately diluted in pooled human serum to yield test samples at the following concentrations: 0.30, 0.70, 1.20, and 3.00 µg/mL. Prepared samples were quantitatively assessed using an enzyme-linked immunosorbent assay (ELISA) and qualitatively using Remi-check Q, and the results obtained for the originator and biosimilar product were compared. For both originator and biosimilar infliximab, Remi-check Q yielded a negative result for all 0.30 and 0.70 µg/mL samples and a positive result for all 3.00 µg/mL samples. However, negative results were obtained with a fraction of the 1.20 µg/mL samples (biosimilar, 4/15; originator, 3/15). Concurrence rates between the results of quantitative ELISA and qualitative Remi-check Q analyses were comparable between originator and biosimilar infliximab at all tested concentrations. These results indicate that Remi-check Q yields comparable results for biosimilar infliximab and the originator product on being used as a qualitative assay for trough serum levels.

Serum golimumab concentration and anti-drug antibodies are associated with treatment response and drug survival in patients with inflammatory joint diseases: data from the NOR-DMARD study

Objectives: This study aimed to identify the therapeutic target concentration and frequency of anti-drug antibodies (ADAbs) in golimumab-treated patients with inflammatory joint disease (IJD).Method: Associations between golimumab concentration, ADAbs, and treatment response were examined in 91 patients with IJD [41 axial spondyloarthritis (axSpA), 20 rheumatoid arthritis (RA), and 30 psoriatic arthritis (PsA)] included in the NOR-DMARD study. Treatment response was defined by Ankylosing Spondylitis Disease Activity Score (ASDAS) clinically important improvement in axSpA, European League Against Rheumatism (EULAR) good/moderate response in RA, and improvement of ≥ 50% in modified Disease Activity index for PSoriatic Arthritis (DAPSA) (28 swollen/tender joint counts) in PsA. Serum drug concentrations and ADAbs were analysed using automated in-house assays.Results: At inclusion, 42% were biological disease-modifying anti-rheumatic drug naïve and 42% used concomitant synthetic disease-modifying anti-rheumatic drug. The median golimumab concentration was 2.2 (interquartile range 1.0-3.5) mg/L. The proportions of responders after 3 months among patients with golimumab concentration < 1.0, 1.0-3.9, and ≥ 4.0 mg/L were 19%, 49%, and 74%, respectively. A higher rate of treatment discontinuation was seen in patients with serum golimumab concentration < 1.0 compared to ≥ 1.0 mg/L (hazard ratio 3.3, 95% confidence interval 1.8-6.0, p < 0.05). ADAbs were detected in 6%, and were associated with lower drug concentrations and both reduced treatment response and drug survival.Conclusions: Golimumab concentrations ≥ 1.0 mg/L were associated with improved treatment response and better drug survival, although some patients may benefit from higher concentrations. This study suggests a rationale for dosing guided by therapeutic drug monitoring in golimumab-treated patients with IJD. The results should be confirmed in larger studies including trough samples, and the efficacy of such a strategy must be examined in randomized controlled trials.

Variability of rituximab and tocilizumab trough concentrations in patients with rheumatoid arthritis

Patients with rheumatoid arthritis (RA) are eligible for treatment with therapeutic monoclonal antibodies (mAbs) that target tumor necrosis factor α (TNFα), as well as others, such as rituximab (RTX) and tocilizumab (TCZ). Although pharmacokinetic variability and the link between concentration-clinical response of anti-TNFα mAbs have been well-described, little is known about RTX and TCZ. We aimed to evaluate the variability of RTX and TCZ serum concentrations in RA patients treated in second-line and the relationship between RTX/TCZ concentrations and the clinical response. Serum mAb trough concentrations of RA patients treated with RTX (n = 35) or TCZ (n = 46) were determined at week 24 by liquid chromatography-tandem mass spectrometry. The clinical response was assessed at week 24 by the change in the disease activity score in the 28 joints-erythrocyte sedimentation rate from baseline (ΔDAS28-Erythrocyte Sedimentation Rate) and according to the European League Against Rheumatism (EULAR) recommendations. RTX and TCZ trough concentrations were highly variable, with a coefficient of variation of 171.3% for RTX (median [10th-90th percentiles]: <1.0 µg/mL [<1.0-5.1]) and 132.6% for TCZ (median [10th-90th percentiles]: 5.4 µg/mL [<1.0-27.8]). Univariate analysis did not identify any determinants of such variability, except cotreatment with methotrexate, which was associated with lower RTX concentrations (P = 0.03). The response to treatment was not related to the RTX or TCZ trough concentration. RTX and TCZ trough concentrations at 24 weeks were highly variable in RA patients treated in the second line, without any link concentration-clinical response having been demonstrated.

The potential value of blood monitoring of biologic drugs used in the treatment of rheumatoid arthritis

The advent of biological therapies has been a major therapeutic advance in rheumatology. Many patients now enjoy improved quality of life through better disease control. The number of therapies continues to grow both within drug class (including biosimilar drugs) and via new mechanisms. For the first time, nonbiological drugs such as small-molecule inhibitors (Janus kinase inhibitors) have shown clinical equivalence. However, clinical unmet need remains with up to a third of patients commenced on a biologic therapy having minimal or no response: (a) Generally, the first biologic used secures the best response, with likelihood of remission falling thereafter with successive therapies; (b) the success of strategy trials using biological therapies can be difficult to replicate in clinical practice due to a combination of patient factors and service limitations. Accordingly, ensuring optimization of initial treatment is an important consideration before switching to alternatives. Therapeutic drug monitoring (TDM) is the measurement of serum levels of a biologic drug with the aim of improving patient care. It is usually combined with detection of any antidrug antibodies that could neutralize the effect of the therapy. This technology has the potential to be a form of 'personalized medicine' by individualizing therapy, in particular, dosing and likelihood of sustained treatment response. It requires a clear relationship between drug dose, blood concentration and therapeutic effect. This paper will outline the technology behind TDM and unpack what we can learn from our colleagues in gastroenterology, where the adoption of TDM is at a more advanced stage than in rheumatology. It will explore and set out a number of clinical scenarios where rheumatologists might find TDM helpful in day-to-day practice. Finally, an outline is given of international developments, including regulatory body appraisals and guideline development.

Associations between certolizumab pegol serum levels, anti-drug antibodies and treatment response in patients with inflammatory joint diseases: data from the NOR-DMARD study

OBJECTIVES

To identify a therapeutic target interval for certolizumab pegol drug levels and examine the influence of anti-drug antibodies in patients with inflammatory joint diseases.

METHODS

Certolizumab pegol and anti-drug antibody levels were measured in serum samples collected after 3 months of certolizumab pegol treatment in 268 patients with inflammatory joint diseases (116 axial spondyloarthritis, 91 rheumatoid arthritis and 61 psoriatic arthritis) in the NOR-DMARD study. Treatment response was defined by Ankylosing Spondylitis Disease Activity Score Clinically important improvement in axial spondyloarthritis, European League Against Rheumatism good/moderate response in rheumatoid arthritis, and improvement in 28-joint Disease Activity Score of ≥ 0.6 in PsA. Serum drug levels and anti-drug antibodies were analysed using automated in-house assays.

RESULTS

Certolizumab pegol serum levels varied considerably between individuals (median (IQR) 32.9 (17.3-43.9) mg/L). Certolizumab pegol level ≥ 20 mg/L was associated with treatment response for the total inflammatory joint disease population, with odds ratio (OR) 2.3 (95% CI 1.2-4.5, P = 0.01) and OR 1.9 (95% CI 1.0-3.5, P = 0.05) after 3 and 6 months of treatment, respectively. For individual diagnoses, this association was most consistent for axial spondyloarthritis, with OR 3.4 (95% CI 1.0-11.1, P < 0.05) and OR 3.3 (95% CI 1.0-10.8, P < 0.05), respectively. Certolizumab pegol level > 40 mg/L was not associated with any additional benefit for any of the diagnoses. Anti-drug antibodies were detected in 6.1% (19/310) of samples and were associated with low certolizumab pegol levels (P < 0.01).

CONCLUSIONS

Serum certolizumab pegol levels 20-40 mg/L were associated with treatment response in inflammatory joint diseases. Our study is the first to show this association in axial spondyloarthritis and psoriatic arthritis patients. The results suggest a possible benefit of therapeutic drug monitoring in patients with inflammatory joint disease on certolizumab pegol treatment.

TRIAL REGISTRATION

NCT01581294, April 2012.

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.

Multiplexed monitoring of therapeutic antibodies for inflammatory diseases using Fab-selective proteolysis nSMOL coupled with LC-MS

Monoclonal antibodies have accelerated the availability of treatment options for many diseases in which the molecular mechanism has been elucidated in detail. Therefore, an assay that can universally analyze antibodies for clinical pharmacokinetics and cross-sectional studies would be indispensable. We have developed a universal antibody bioanalysis with a Fab-selective tryptic reaction, named nano-surface and molecular-orientation limited (nSMOL) proteolysis, that collects the specific antibody signature peptides in biological samples. Using the nSMOL method, we have fully validated the bioanalysis of many antibodies, Fc-fusion proteins, and their biosimilars. Inflammatory immune diseases often require long-term clinical management because of the remission and relapse observed. Accurate antibody monitoring in systemic circulation could contribute to the improvement of clinical outcomes. Because several biopharmaceuticals can be selected as practical treatment options, the assay development that quantitates many antibodies simultaneously would be applicable in many theraprutic monitoring. In this study, we have validated the LC-MS bioanalysis method for seven-mixed antibodies (Infliximab, Adalimumab, Ustekinumab, Golimumab, Eculizumab, Etanercept, and Abatacept) using the nSMOL normal reaction condition and two-mixed antibodies (Tocilizumab and Mepolizumab) using the acidified reduction acceleration condition, as reported in our previous papers. Moreover, this multiplexed assay has been verified using clinical patient samples. The nSMOL approach enables the quantitation of several immunosuppressive antibodies simultaneously in human serum, and nSMOL can potentially be applicable to the drug-drug interaction assays or therapeutic antibody monitoring of several inflammatory immune diseases to optimize administration.

Pharmacodynamic monitoring using biomarkers to individualize pharmacotherapy

Drug doses are often titrated upon their clinical effects (e.g., blood pressure). Unfortunately, for many drugs there is no direct, clinical read-out to estimate dose adequateness. Alternatively, drug dosing is based on the maximum tolerated dose approach or therapeutic drug monitoring. However, the concentration-response curves may be flattened or bell-shaped as suggested for some ‘biologicals’. Together, these aspects raise the question why drug dosing is not individualized by pharmacodynamic monitoring. Evaluating the effects of drugs at their pharmacological target or meaningful biomarkers might indicate nonresponders, objectively quantify the maximum molecular effect and thus restrict overdose and underdosing. This review outlines the theory and biological or technical prerequisites for biomarker-based pharmacodynamic monitoring, and highlights selected examples from different fields of clinical medicine.

High-Throughput Bioanalysis of Bevacizumab in Human Plasma Based on Enzyme-Linked Aptamer Assay Using Anti-Idiotype DNA Aptamer

We propose a highly selective, sensitive, accurate, and high-throughput bioanalysis method for bevacizumab utilizing an anti-idiotype DNA aptamer. With this method, bevacizumab in a plasma sample was reacted in a 96-well plate immobilized with the aptamer and further reacted with a protein A-HRP conjugate. The resulting HRP activity was colorimetrically detected using a microplate reader. The calibration curve of bevacizumab ranged from 0.05 to 5.0 μg/mL, and showed a good correlation coefficient ( r² = 1.000). The limit of detection was 2.09 ng/mL. We also demonstrated both the possibility of highly sensitive detection using luminol chemiluminescence and the repeated use of affinity plates. The proposed method is applicable for planning optimal therapeutic programs and for an evaluation of the biological equivalencies in the development of biosimilars.

Verification between Original and Biosimilar Therapeutic Antibody Infliximab Using nSMOL Coupled LC-MS Bioanalysis in Human Serum

Background:

Infliximab (IFX) is a chimeric therapeutic monoclonal antibody targeting tumor necrosis factor alpha (TNFα)-mediated inflammatory immune diseases. However, despite of an initial good clinical response, decrease in response to long-term treatment is a common observation.

Objective:

Recent studies suggest that IFX level in circulation has a correlation with clinical bioavailabil-ity. Therefore, the management of IFX dosage for individual manifestation by IFX monitoring may be valuable for the improvement of therapeutic response and outcomes.

Method:

In order to develop a broad IFX therapeutic monitoring in human serum, we have developed the validated IFX bioanalysis for RemicadeTM and its biosimilar product using our nano-surface and molecu-lar-orientation limited proteolysis (nSMOL) technology coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The nSMOL chemistry has a unique property of Fab-selective prote-olysis, and makes it possible a global bioanalysis for many monoclonal antibodies.

Results:

The quantitation range of IFX in serum was from 0.293 to 300 μg/ml with good linearity. Quan-titation verification at the concentrations of 0.293, 0.879, 14.1 and 240 μg/ml was within 1.56-7.53% of precision and 98.9-111% of accuracy using H-chain signature peptide SINSATHYAESVK. Moreover, cross-verified bioanalysis of Remicade quantitation using biosimilar standard, and its opposite combina-tion, obtained an identical and inter-comparative results.

Conclusion:

The nSMOL strategy has the potential as a practical therapeutic monitoring technology in IFX therapeutic applications.

Practical Aspects of Biological Throught Levels and Antidrug Antibodies in Rheumatoid Arthritis and Spondyloarthritis

OBJECTIVES

Issue recommendations on practical aspects of the monitoring of levels of biological drugs that may be useful for rheumatologists.

METHODS

We conducted a systematic review of studies in which drug and anti-drug antibody levels were determined in patients with rheumatoid arthritis (RA) or spondyloarthritis (SpA) to study whether they could predict different outcomes. In light of the results of the review, a group of experts discussed under what circumstances testing biological drug levels and their antibodies could be useful. The discussion resulted in a series of clinical questions that were answered with the scientific evidence collected, and in algorithms that facilitate decision making.

RESULTS

It was established that the determination of drug levels can be especially useful in two clinical situations, on treatment failure (primary or secondary) and on sustained remission. It is also reviewed which laboratory technique and timing for sample drawing are the most suitable for the measurement. Recommendations are issued on the interpretation of drug levels and on factors to be taken into account (for example, body mass index and disease modifying drugs).

CONCLUSIONS

Evidence-based algorithms and guidelines have been established to test drug levels and anti-drug antibodies in patients with RA and SpA, which can help clinical decision making.

Current Practice for Therapeutic Drug Monitoring of Biopharmaceuticals in Rheumatoid Arthritis

The treatment of rheumatoid arthritis (RA) has largely improved in the biopharmaceutical era. These compounds, primarily tumor necrosis factor (TNF) inhibitors, are effective, but some patients may show poor response, sometimes because of the presence of antidrug antibodies (ADAs). In some instances, clinicians may increase or taper the dose depending on the clinical response. Besides the current clinical-based practice, a tailored strategy based on drug monitoring has emerged as a way to improve the use of these drugs. However, the relevance of this therapeutic drug monitoring (TDM) of biopharmaceuticals in RA is still unknown. In this literature review, we examine the most relevant articles dealing with the concentration-response relationship, ADA detection and pharmacokinetics in RA patients receiving biopharmaceuticals. A concentration-response relationship was clearly established for TNF inhibitors. Moreover, ADA positivity was associated with low drug concentrations, poor clinical outcome, and reduced drug survival for TNF-inhibitor monoclonal antibodies. Concomitant use of disease-modifying antirheumatic drugs, especially methotrexate, is associated with good clinical outcome, increased drug concentrations, and reduced immunogenicity. Strategies based on TDM of TNF inhibitors seem promising for RA, but randomized controlled trials are required to support this. A concentration-response relationship may exist with tocilizumab, and immunogenicity seems rare. Finally, the relevance of TDM for RA patients receiving rituximab and abatacept remains unclear.

Development of a general method for quantifying IgG-based therapeutic monoclonal antibodies in human plasma using protein G purification coupled with a two internal standard calibration strategy using LC-MS/MS

Monoclonal antibody (mAb) drugs have generated much interest in recent years for treating various diseases. Immunoglobulin G (IgG) represents a high percentage of mAb drugs that have been approved by the Food and Drug Administration (FDA). To facilitate therapeutic drug monitoring and pharmacokinetic/pharmacodynamic studies, we developed a general liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify the concentration of IgG-based mAbs in human plasma. Three IgG-based drugs (bevacizumab, nivolumab and pembrolizumab) were selected to demonstrate our method. Protein G beads were used for sample pretreatment due to their universal ability to trap IgG-based drugs. Surrogate peptides that were obtained after trypsin digestion were quantified by using LC-MS/MS. To calibrate sample preparation errors and matrix effects that occur during LC-MS/MS analysis, we used two internal standards (IS) method that include the IgG-based drug-IS tocilizumab and post-column infused IS. Using two internal standards was found to effectively improve quantification accuracy, which was within 15% for all mAb drugs that were tested at three different concentrations. This general method was validated in term of its precision, accuracy, linearity and sensitivity for 3 demonstration mAb drugs. The successful application of the method to clinical samples demonstrated its' applicability in clinical analysis. It is anticipated that this general method could be applied to other mAb-based drugs for use in precision medicine and clinical studies.

Recent advances in mass spectrometry-based approaches for proteomics and biologics: Great contribution for developing therapeutic antibodies

Since the turn of the century, mass spectrometry (MS) technologies have continued to improve dramatically, and advanced strategies that were impossible a decade ago are increasingly becoming available. The basic characteristics behind these advancements are MS resolution, quantitative accuracy, and information science for appropriate data processing. The spectral data from MS contain various types of information. The benefits of improving the resolution of MS data include accurate molecular structural-derived information, and as a result, we can obtain a refined biomolecular structure determination in a sequential and large-scale manner. Moreover, in MS data, not only accurate structural information but also the generated ion amount plays an important rule. This progress has greatly contributed a research field that captures biological events as a system by comprehensively tracing the various changes in biomolecular dynamics. The sequential changes of proteome expression in biological pathways are very essential, and the amounts of the changes often directly become the targets of drug discovery or indicators of clinical efficacy. To take this proteomic approach, it is necessary to separate the individual MS spectra derived from each biomolecule in the complexed biological samples. MS itself is not so infinite to perform the all peak separation, and we should consider improving the methods for sample processing and purification to make them suitable for injection into MS. The above-described characteristics can only be achieved using MS with any analytical instrument. Moreover, MS is expected to be applied and expand into many fields, not only basic life sciences but also forensic medicine, plant sciences, materials, and natural products. In this review, we focus on the technical fundamentals and future aspects of the strategies for accurate structural identification, structure-indicated quantitation, and on the challenges for pharmacokinetics of high-molecular-weight protein biopharmaceuticals.

Practical recommendations for the use of therapeutic drug monitoring of biopharmaceuticals in inflammatory diseases

Biopharmaceuticals directed against tumor necrosis factor-alpha, integrins, interleukins, interferons and their receptors have become key agents for the management of inflammatory diseases in the fields of gastroenterology, rheumatology, dermatology and neurology. However, response to these treatments is far from optimal. Therapeutic failure has been attributed in part to inadequate serum concentrations of the drug and the formation of antidrug antibodies (ADA). Therapeutic drug monitoring (TDM) based on drug concentrations and ADA represents a pharmacologically sound tool for guiding dosage adjustments to optimize exposure. Although becoming standard practice in tertiary care centers, the widespread accessibility and recognition of TDM is hindered by several hurdles, including a lack of education of health care providers on TDM. In this paper, the Monitoring of monoclonal Antibodies Group in Europe (MAGE) provides an introduction on the fundamental principles of the concept of TDM, aiming to educate clinicians and assist them in the process of implementing TDM of anti-inflammatory biopharmaceuticals.

Predictive Value of Serum Infliximab Levels at Induction Phase in Rheumatoid Arthritis Patients

Background:

The Infliximab, has proven effective in treating rheumatoid arthritis (RA). A good clinical response is usually associated with high serum drug levels. Development of antibodies toward Infliximab (ATI) can increase drug clearance, leading to treatment failure.

Aims:

To analyze whether serum Infliximab trough levels (ITL) at the induction phase are associated with Infliximab clearance and clinical outcomes at week(W) 54 and to investigate the association with immunogenicity development.

Methods:

Observational retrospective study in which ITL from 66 RA patients were measured by capture ELISA at W0, W2, W6, W14 and 22. Patients were classified as ITLpos if Infliximab was detectable at W54 and ITLneg otherwise. ATI were assayed by bridging ELISA and by two drug-tolerant assays. ITL cut-off values were established by ROC curves. The association between ITL at early-stage and clearance of Infliximab at W54 was analyzed by univariable and multivariable logistic regression.

Results:

ITLneg patients (n=25) always had significantly lower Infliximab levels than ITLpos (n=41). An ITL value of 4.4 μg/mL at W6 best predicted W54 Infliximab absence. In the multivariable analysis, only ITL below the cut-off at W6 (OR: 86.6; 95%CI: 6.58-1139.99) and non-use of methotrexate (OR: 6.9; 95%CI: 1.04-45.84) remained significantly associated with W54 Infliximab absence. ATI were more frequent in patients with ITL below the cut-off at W6.

Conclusions:

In RA, ITL at induction phase are inversely associated with Infliximab clearance and clinical outcomes at W54. ATI was the main reason for low early ITL. A predictive value of ITL at W6 was found as a useful prognostic measure of treatment efficacy.

Theranostic of biopharmaceuticals

Monoclonal antibodies (mAbs) and fusion proteins with an Fc portion of immunoglobulin G (IgG) are emblematic of the remarkable expansion of biopharmaceuticals. Despite their biological origin, these products display an interindividual variability in their efficacy and/or side effects, which must be taken into consideration. Biological monitoring allowing for adapted prescription and dose adjustments may lead to therapeutic optimization and limitation of the high costs of these drugs. Herein, we review the biological theranostic of mAbs and Fc fusion proteins, including pre-treatment analyses, monitoring of efficacy, therapeutic drug monitoring, and monitoring of side effects. Supported by concrete evidence, a specific interest is given to individualised therapeutic monitoring that combines intention to treat, biomarkers of efficacy and adaptation of serum concentrations.

Clinical Pharmacokinetics and Pharmacodynamics of Monoclonal Antibodies Approved to Treat Rheumatoid Arthritis

Monoclonal antibodies (mAbs) are increasingly used to treat rheumatoid arthritis (RA). At present, anti-tumor necrosis factor-α drugs (infliximab, adalimumab, certolizumab pegol, and golimumab), rituximab, and tocilizumab are approved for RA treatment. This review focuses on the pharmacokinetics and pharmacodynamics of mAbs approved in RA. Being large proteins, mAbs exhibit complex pharmacokinetic and pharmacodynamic properties. In particular, owing to the interactions of mAbs with their antigenic targets, the pharmacokinetics of mAbs depends on target turnover and exhibits non-specific (linear) and target-mediated (often nonlinear) clearances. Their volume of distribution is low (3-4 L) and their elimination half-life usually ranges from 2 to 3 weeks. The inter-individual pharmacokinetic variability of mAbs is usually large and is partly explained by differences in antigenic burden or by anti-drug antibodies, which accelerate mAb elimination. The inter-individual variability of clinical response is large and influenced by the pharmacokinetics. The analysis of mAbs concentration-effect relationship relies more and more often on pharmacokinetic-pharmacodynamic modeling; these models being suitable for dosing optimization. Even if adverse effects of mAbs used in RA are well known, the relationship between mAb concentration and adverse effects is poorly documented, especially for anti-tumor necrosis factor-α mAbs. Overall, RA patients treated with mAbs should benefit from individualized dosing strategies. Because of the complexity of their pharmacokinetics and mechanisms of action, the current dosing strategy of mAbs is not based on sound knowledge. New studies are needed to assess individual dosing regimen, adjusted notably to disease activity.

Therapeutic drug monitoring of monoclonal antibodies in inflammatory and malignant disease: Translating TNF-α experience to oncology

Lack of response to monoclonal antibodies (mAbs) has been associated with inadequate mAb serum concentrations. Therapeutic drug monitoring (TDM) of mAbs has the potential to guide to more effective dosing in individual patients. This review discusses the mechanisms responsible for interpatient variability of mAb pharmacokinetics, summarizes exposure-response data of mAbs used in inflammatory and malignant disease, presents current evidence of mAb-TDM in inflammatory disease, and provides hurdles and required future steps for further implementing mAb-TDM.

Effect of Infliximab Dose Increase in Rheumatoid Arthritis at Different Trough Concentrations: A Cohort Study in Clinical Practice Conditions

Background

Evidence supporting treatment intensification in rheumatoid arthritis (RA) is limited and controversial. We explored outcomes of infliximab dose increases and accounted for pre-existing trough levels in patients with active RA.

Methods

This study was a retrospective study of 42 RA patients who received increased infliximab following an insufficient response (DAS28 >3.2). Serum concentrations of infliximab and antibodies to infliximab (ATI) and DAS28 and EULAR clinical response parameters were recorded for 1 year. Analyses were performed in three patient groups that were defined by infliximab serum concentration prior to treatment enhancement: no detectable, low (<1.1 μg/mL) or high (≥1.1 μg/mL) drug levels.

Results

No circulating infliximab was detected in 20 patients (47.6%), but 13 (31%) and 9 (21.4%) patients exhibited low and high levels, respectively. ATI was only detected in patients with no detectable drug levels because the drug interferes with ELISA. DAS28 disease activity globally showed a modest improvement after dose escalation, but this improvement did not persist after 6 and 12 months. Infliximab serum levels increased significantly in the high group (p = 0.016), but no increase was achieved in the low and no detectable groups. The three study groups exhibited similar disease activity over time, and no improvement was observed in the non-responder EULAR rates.

Conclusion

These results suggest that the efficacy of an infliximab dose increase is limited, and the response is independent of the infliximab trough serum concentration that is achieved prior to escalation.

Therapeutic drug monitoring in rheumatic diseases: utile or futile?

Rapid and effective suppression of inflammation is a primary goal in the treatment of rheumatic diseases. However, the therapeutic effect of most medications may be slow to manifest, in the order of weeks or months in the case of DMARDs. Monitoring of drug concentrations allows the possibility of appropriate dose adjustment or changes in medication to achieve more rapid or better outcomes. We review the evidence for drug concentration monitoring. Despite the theoretical utility for monitoring of MTX polyglutamate concentrations in red blood cells in patients with RA, studies have not shown a clear association between concentrations and either efficacy or toxicity and routine measurement is not yet recommended. Small studies associating disease control with concentrations of anti-TNF therapies and anti-drug antibodies suggest that routine monitoring may be useful in the future. However, the data are not yet sufficient for this recommendation. With the use of allopurinol in gout, there is a putative therapeutic range for the active metabolite oxypurinol; however, adjusting the allopurinol dose to achieve a target urate concentration is likely to be most effective, and measuring oxypurinol may be best suited to assessing drug adherence. Although measuring thiopurine metabolite concentrations with AZA therapy has been shown to be useful in IBD, studies in rheumatic diseases have so far failed to confirm a useful association between concentrations and disease control or drug toxicity. Whole blood concentrations of HCQ have been associated with disease control in SLE and future studies may be able to determine a therapeutic range.

Monitoring antigen-specific biologics: current knowledge and future prospects

An increasing number of antigen-specific biologics have been introduced into clinical practice, and the ones that arrived first have already reached the end of their patented life span. Despite the use of these agents for over a decade, individualized dosing is not standard practice. Most patients are treated according to treatment protocols, with a fixed dose administered at fixed time intervals. Although the between-subject variability in the volume of distribution is small, there is a moderate to high between-subject variability in the clearance of these biologics. The formation of neutralizing antidrug antibodies (ADAs) further contributes to the variability in the pharmacokinetics and pharmacodynamics. After the development of assays to detect biologic drug serum concentrations and ADA titers, the first clinical studies in immune-mediated diseases such as rheumatology, gastroenterology, and dermatology have now shown clear concentration-effect relationships. By monitoring the serum trough concentrations of biologics, patients with high drug exposure could be identified and dose reductions in those patients may lead to improved safety and substantial cost savings. Low biologic drug serum concentrations may be due to the development of ADAs, and if these are detected, a switch to an alternative treatment is indicated. We envision a vast expansion of therapeutic drug monitoring to support the use of biologics, and we urge the International Association of Therapeutic Drug Monitoring and Clinical Toxicology to embark on initiatives to investigate the contribution of therapeutic drug monitoring to this field.

Immunogenicity, adalimumab levels and clinical response in ankylosing spondylitis patients during 24 weeks of follow-up

BACKGROUND

Immunogenicity influences adalimumab levels and therefore clinical response in patients with rheumatic diseases.

OBJECTIVES

To study the relationship between clinical response, adalimumab levels and antidrug antibodies (ADAb) in ankylosing spondylitis (AS).

METHODS

Observational cohort study of 115 consecutive AS patients treated with adalimumab in the Netherlands (n=85) and Taiwan (n=30), monitored during 24 weeks. Adalimumab levels and ADAb titres were determined using an ELISA and an antigen binding test (ABT), respectively, designed by Sanquin Research, Amsterdam. Response to adalimumab treatment was defined as a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) response, and disease activity was measured using the Ankylosing Spondylitis Disease Activity Score using C-reactive protein (CRP) (ASDAS).

RESULTS

At baseline, median BASDAI (IQR) was 6.4 (4.5-7.6) and mean ASDAS (SD) was 3.5 (1.0). After 24 weeks, 49 (42.6%) patients were BASDAI50 responders and mean ASDAS (SD) for responders was 1.5 (1.0) vs 2.6 (1.0) for non-responders (p<0.001). Thirty-one (27.0%) patients had detectable ADAb. After 24 weeks, adalimumab levels (mg/L) (IQR) were significantly higher in ADAb-negative patients than in ADAb-positive patients (12.7 (8.2-18.0) vs 1.2 (0.0-2.0), (p<0.001)). A significant association was demonstrated between adalimumab levels and ASDAS (p=0.02; RC -1.1; 95% CI -2.0 to -0.2). Eleven (9.6%) patients had no detectable adalimumab levels and high detectable ADAb titres (>100 AU/mL). In these patients, CRP and erythrocyte sedimentation rate remained elevated during treatment.

CONCLUSIONS

Adalimumab levels are related to clinical response in AS patients measured with ASDAS and are influenced by ADAb detectable with an ABT.

Targeting monocytes/macrophages in the treatment of rheumatoid arthritis

Biotherapies have revolutionized the treatment of RA. However, much work is needed to understand all the mechanisms of these biotherapies, and alternatives are needed to circumvent adverse effects and the high cost of these long-lasting treatments. In this article we outline some of the approaches we have used to target monocytes/macrophages as major components of inflammation and bone homeostasis. We also discuss how anti-TNF-α antibodies target monocytes/macrophages in the complex mechanisms contributing to inhibition of inflammation.

Low infliximab serum trough levels and anti-infliximab antibodies are prevalent in rheumatoid arthritis patients treated with infliximab in daily clinical practice: results of an observational cohort study

Background

To get insight in the prevalence of high, or low/no serum infliximab trough levels in patients with low disease activity and if serum trough levels are stable and reliable longitudinally we conducted a prospective cohort study

Methods

In a longitudinal, observational cohort of RA patients treated with infliximab for at least 6 months, treatment interval, DAS28, infliximab trough levels and anti-infliximab antibodies were assessed. Prevalence of low (<1 mg/l) and high (>5 mg/l) infliximab serum trough levels and anti-infliximab antibodies was recorded. Relationship of a change in anti-infliximab antibodies and treatment interval was described. Reliability of consecutive infliximab serum trough levels and anti-infliximab antibodies in patients with stable DAS28 and treatment was analysed with Spearman correlation and kappa-analysis.

Results

147 patients with a mean disease duration of 11 years (sd7) and DAS28 of 3.5 (sd1.3) at baseline were followed during 1.5 years. Inter-individual variability in infliximab levels in patients with low DAS28 was high (median 1.4 mg/L, IQR 3.35), with 31% (95%CI: 20-42%) having low (<1 mg/L) and 14% (95%CI 5–22) high trough levels (>5 mg/L). Interestingly also in RA patients with DAS28 ≤ 3.2, anti-infliximab antibodies were found in one-third of the patients, with half of them having antibodies every visit during a median of more than one year. Agreement for consecutive measurements of serum trough levels and anti-infliximab antibodies was high in stable patients: r = 0.97 (p = 0.00001) and kappa = 1.0 (SE 0.14) Anti-infliximab antibody appearance was influenced by interval increases (relative risk (RR) 5.2, 2.6-10.7), but patients still showed low infliximab levels.

Conclusions

Low (and high) infliximab serum trough levels are prevalent, interestingly also in patients with low disease activity. Consecutive measurements of serum trough levels and anti-infliximab antibodies are reliable in stable patients. These test could be used to lower or stop infliximab in selected patients.

Etanercept Concentration in Patients with Rheumatoid Arthritis and Its Potential Influence on Treatment Decisions: A Pilot Study

Objective.

For patients with rheumatoid arthritis (RA), recommendations are inconclusive about whether tumor necrosis factor-α (TNF-α)-blocker therapy should be evaluated at 3 or 6 months. Biomarkers are needed to predict at 3 months which patients would benefit from further treatment because of nonoptimal response. Our objective was to investigate whether serum etanercept (ETN) concentrations and anti-ETN antibodies at 3 months are predictors of clinical response to ETN at 6 months in patients with RA in terms of European League Against Rheumatism criteria and Disease Activity Score in 28 joints (DAS28).

Methods.

Between 2009 and 2010, we included 19 women with active RA who were candidates for ETN therapy. Response criteria were evaluated at 3 and 6 months. Serum concentrations of ETN and anti-ETN antibodies were measured by ELISA at baseline and at 3 and 6 months.

Results.

Eighteen patients completed followup. Three-month ETN concentrations were lower for 6-month nonresponders than responders (p = 0.03). Three-month ETN levels correlated significantly with change in DAS28 between baseline and 6 months (r = −0.62, p = 0.006). The best predictor of response at 6 months was observed with an ETN threshold of 3.1 μg/ml at 3 months. No anti-ETN antibodies were found.

Conclusion.

ETN concentrations at 3 months predict response to ETN therapy at 6 months. Low ETN concentrations could explain the absence of response to ETN, suggesting that patients with low ETN levels could benefit from increased ETN dose or earlier interruption of treatment.

Antibodies toward infliximab are associated with low infliximab concentration at treatment initiation and poor infliximab maintenance in rheumatic diseases

INTRODUCTION

A proportion of patients receiving infliximab have antibodies toward infliximab (ATI), which are associated with increased risk of infusion reaction and reduced response to treatment. We studied the association of infliximab concentration at treatment initiation and development of ATI as well as the association of the presence of ATI and maintenance of infliximab.

METHODS

All patients with rheumatoid arthritis (RA) or spondyloarthritis (SpA) receiving infliximab beginning in December 2005 were retrospectively followed until January 2009 or until infliximab discontinuation. Trough serum infliximab and ATI concentrations were measured at each visit. The patients were separated into two groups: ATI(pos) if ATI were detected at least once during the follow-up period and ATI(neg) otherwise. Repeated measures analysis of variance was used to study the association of infliximab concentration at treatment initiation and the development of ATI. Maintenance of infliximab in the two groups was studied by using Kaplan-Meier curves.

RESULTS

We included 108 patients: 17 with RA and 91 with SpA. ATI were detected in 21 patients (19%). The median time to ATI detection after initiation of infliximab was 3.7 months (1.7 to 26.0 months). For both RA and SpA patients, trough infliximab concentration during the initiation period was significantly lower for ATI(pos) than ATI(neg) patients. RA patients showed maintenance of infliximab at a median of 19.5 months (5.0 to 31.0 months) and 12.0 months (2.0 to 24.0 months) for ATI(neg) and ATI(pos) groups, respectively (P = 0.08). SpA patients showed infliximab maintenance at a median of 16.0 months (3.0 to 34.0 months) and 9.5 months (3.0 to 39.0 months) for ATI(neg) and ATI(pos) groups, respectively (P = 0.20). Among SpA patients, those who were being treated concomitantly with methotrexate had a lower risk of developing ATI than patients not taking methotrexate (0 of 14 patients (0%) vs. 25 of 77 patients (32%); P = 0.03).

CONCLUSIONS

High concentrations of infliximab during treatment initiation reduce the development of ATI, and the absence of ATI may be associated with prolonged maintenance of infliximab. Thus, trough serum infliximab concentration should be monitored early in patients with rheumatic diseases.

Influence of immunogenicity on the efficacy of long-term treatment with infliximab in rheumatoid arthritis

OBJECTIVE

To analyse the clinical relevance of the production of anti-infliximab antibodies (anti-infliximab Abs) in patients with RA undergoing infliximab treatment over a prolonged period of time.

METHODS

Clinical characteristics, serum trough infliximab and antibody levels were evaluated in 85 RA patients treated with infliximab for a median of 4.42 (interval 0.4-10.2) years. DAS in 28 joints (DAS-28), EULAR response criteria and survival of treatment were assessed at 3 time points (6 months, 12 months and >4 years).

RESULTS

Antibodies against infliximab were detected in 28 (32.9%) patients and were present in all EULAR non-responder patients. Antibody levels were higher in EULAR non-responders throughout the study period (P = 0.05 at 6 months, P = 0.02 at 1 year, P = 0.003 at >4 years) compared with EULAR (good and moderate) responders. Nine (10.5%) patients, all of them with high-serum anti-infliximab Ab levels, developed infusion-related reactions. Patients with anti-infliximab Abs more often required increased infliximab doses (51.7%) (P = 0.032) and median survival time on treatment was shorter (4.15 vs 8.89 years) (P = 0.0006). MTX co-therapy was not associated with lower proportion of anti-infliximab Ab-positive patients, but those receiving both infliximab and MTX had lower levels of anti-infliximab Abs (P = 0.073) and longer survival (P = 0.015) on treatment.

CONCLUSION

The formation of anti-infliximab Abs during treatment with infliximab is associated with a loss of clinical response, the appearance of infusion reactions and discontinuation of treatment.

Appropriate infliximab infusion dosage and monitoring: results of a panel meeting of rheumatologists, dermatologists and gastroenterologists

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Infliximab is an effective treatment for rheumatoid arthritis, ankylosing spondylitis, Crohn's disease (both adult and paediatric), ulcerative colitis, psoriatic arthritis and plaque psoriasis and national and international guidelines have been developed for each indication.

WHAT THIS STUDY ADDS

This study is the first study which compared current international, national and local guidelines from the medical specialties involved in the treatment with infliximab on the following topics: indication, dosage, synergy and monitoring of vital signs.

AIMS

Infliximab, an anti-TNF biologic agent, is currently indicated and reimbursed for rheumatoid arthritis, ankylosing spondylitis, Crohn's disease (both adult and paediatric), ulcerative colitis, psoriatic arthritis and plaque psoriasis. Development of national and international guidelines for rheumatology, gastroenterology and dermatology, was mostly based on clinical studies and expert opinion. The aim of this study was to compare available guidelines and local protocols for rheumatology, dermatology and gastroenterology, regarding dosage of infliximab, synergy of infliximab with concomitant medication and monitoring of vital signs during infliximab administration, for achieving optimal care.

METHODS

Current international, national and local guidelines on the use of infliximab were reviewed and compared, differences and shortcomings were identified, and optimal treatment schedules discussed during a meeting (July 2008) of clinical experts and researchers from three departments of a Dutch university hospital.

RESULTS

Recommended dosages of infliximab are not equal for different indications. Loss of response to infliximab is a common problem encountered within the three medical specialties, but indications for adjustments in treatment schedules are lacking in all of the guidelines. Monitoring of vital signs (blood pressure, pulse, temperature) during infusion with infliximab is common practice and recommended by some guidelines. Routine measurement of vital signs is not of any value in predicting or recognizing acute infusion reactions, in our experience, and this is confirmed by literature on inflammatory bowel disease.

CONCLUSION

Different indications encompass different dosing schedules. National and internal guidelines do not provide advice regarding loss of response. Routine measurement of vital signs during infusion is not valuable in detecting acute infusion reactions and should only be performed in case of an acute infusion reaction. These topics need to be studied in future studies and covered in future guidelines.