Lower etanercept levels are associated with high disease activity in ankylosing spondylitis patients at 24 weeks of follow-up

Is the C-reactive protein-to-albumin ratio the most remarkable simple inflammatory marker showing active disease in patients with axial spondyloarthritis, psoriatic arthritis, and rheumatoid arthritis?

OBJECTIVE

To learn which of the simple inflammation markers obtained from routine laboratory tests showed active disease best.

METHODS

The study included 256 patients (102 patients with axial spondyloarthritis [axSpA], 54 with psoriatic arthritis [PsA], and 100 with rheumatoid arthritis [RA]). The results of the routine laboratory tests requested during the outpatient clinic visits of the patients were noted. Inflammation-related ratio/indices were then calculated from these laboratory tests. Active and inactive diseases were defined according to the disease activity scores for each disease. Logistic regression and receiver operating characteristic (ROC) analyses were performed to determine the best laboratory marker(s) showing active disease and its cutoff value for all three diseases.

RESULTS

C-reactive protein to albumin ratio (CAR) was significantly higher in patients with active axSpA, PsA, and RA diseases than those with inactive diseases (p < 0.001, p = 0.006, and p < 0.001, respectively). In the logistic regression analysis, the CAR was the most important predictor of active disease in patients with axSpA, PsA, and RA. CAR had also showed the active disease at an acceptable level in axSpA and PsA and very well in RA. The cutoff values for active disease in axSpA, PsA, and RA were 0.75, 0.92, and 0.89, respectively.

CONCLUSION

CAR may be a promising simple laboratory marker to distinguish active disease in patients with axSpA, PsA, and RA. Key Points • Acute phase reactants and circulating blood cells have become an important target because of the search for a disease activity marker that can be used cheaply and quickly in the daily outpatient routine. • One or more of these simple markers have been previously discussed in various studies with different hypotheses. • We aimed to determine which of the inflammation markers obtained from routine laboratory tests showed active disease and to determine a cutoff value for this/these marker(s). • CAR was the most important simple laboratory marker to distinguish active disease in patients with axSpA, PsA, and RA. In addition, CAR showed the active disease at an acceptable level in axSpA and PsA, and very well in RA.

High BMI is associated with lower TNF-α inhibitor serum trough levels and higher disease activity in patients with axial spondyloarthritis

BACKGROUND

TNF-α inhibitor (TNFi) serum trough levels have previously been found to be related to disease activity in axial spondyloarthritis (axSpA). However, most research regarding serum trough levels has been conducted in patients who only recently started TNFi therapy. Therefore, our objective was to explore TNFi serum trough level measurements in relation to disease activity and BMI in the total axSpA population in daily clinical practice, also including patients on long-term TNFi therapy.

METHODS

Consecutive patients from the Groningen Leeuwarden Axial Spondyloarthritis (GLAS) cohort were approached for a TNFi serum trough level measurement during their regular outpatient visit at the UMCG. Spearman's correlation coefficient was used to analyse the relation of serum trough levels with disease activity and BMI. Logistic regression was performed to analyse the relation between therapeutic drug levels and disease activity, corrected for potential confounders, including BMI.

RESULTS

Thirty-four patients on adalimumab and 21 patients on etanercept were included. Mean age was 45 ± 12 years, 47% were male, median BMI was 26.4 (IQR 23.9-32.5) and median treatment duration was 41 months (range 2-126). According to definitions of Sanquin, 47% of patients had therapeutic serum trough levels. No significant correlations were found between TNFi levels and disease activity (ASDAS-CRP: adalimumab: ρ = -0.16, p = 0.39; etanercept: ρ = -0.29, p = 0.20). TNFi levels were moderately correlated with BMI (adalimumab: ρ = -0.48, p = 0.004; etanercept: ρ = -0.50, p = 0.021). Patients with active disease (ASDAS ≥ 2.1) showed higher BMI than patients with inactive disease (median 29.7 vs. 24.6, p = 0.015). In multivariable regression analyses, BMI was identified as the only confounder for the relationship between therapeutic drug levels and ASDAS.

CONCLUSION

In this cross-sectional, observational study of axSpA patients mainly on long-term treatment with TNFi, higher BMI was significantly associated with lower adalimumab and etanercept serum trough levels and higher disease activity.

Reduced prescription of TNF-inhibitors in chronic arthritis based on therapeutic drug monitoring: A randomized controlled trial

OBJECTIVE

Dosing of tumour necrosis factor-α inhibitors (TNFis) is not personalized causing interindividual variation in serum drug levels; however, dose optimization is not widely implemented. We hypothesized that some patients are overdosed; thus, drug prescription could be reduced by therapeutic drug monitoring (TDM).

METHOD

Independent of disease activity, 239 adults treated for rheumatoid arthritis (n = 99), psoriatic arthritis 15 (n = 48), or spondyloarthritis (n = 92) were recruited for a 48-week prospective, randomized open-label trial. Standard care alone or plus TDM was applied in chronic arthritis patients treated with infliximab (IFX), (n = 81), etanercept (ETN) (n = 79), or adalimumab (ADA) (n = 79). Serum TNFi trough levels assessed at inclusion and every 4 months determined patients within/outside predefined therapeutic intervals, supporting change in prescription or drug switch. The primary endpoint was reduced drug prescription.

RESULTS

Compared to standard care, TDM reduced prescribed IFX [-12% (95% confidence interval -20, -3); p = 0.001] and ETN (-15% (-29, 1); p = 0.01], and prolonged the interdosing intervals of ETN [+235% (38, 432); p = 0.02] and ADA [+28% (6, 51); p = 0.04]. Time to drug switch was accelerated (χ2 = 6.03, p = 0.01). No group differences in adverse events, disease activity, or self-reported outcomes were shown, indicating equally sustained remission.

CONCLUSIONS

TDM reduced prescription of IFX, ETN, and ADA and identified patients benefiting from accelerated drug switch, thereby minimizing treatment failure, risk of toxicity, and unnecessary adverse events.

Etanercept for patients with juvenile idiopathic arthritis: drug levels and influence of concomitant methotrexate: observational study

BACKGROUND

Etanercept (ETN) is widely used tumour necrosis factor (TNF) blocker in the treatment of juvenile idiopathic arthritis (JIA) when traditional synthetic disease modifying antirheumatic drug (sDMARD) therapy is not sufficient. There is limited information about the effects of methotrexate (MTX) on serum ETN concentration in children with JIA. We aimed to investigate whether ETN dose and concomitant MTX would effect ETN serum trough levels in JIA patients, and whether concomitant MTX have an influence on the clinical response in patients with JIA receiving ETN.

METHODS

In this study, we collected the medical record data of 180 JIA patients from eight Finnish pediatric rheumatological centres. All these patients were treated with ETN monotherapy or combination therapy with DMARD. To evaluate the ETN concentrations, blood samples of the patients were collected between injections right before the subsequent drug. Free ETN level was measured from serum.

RESULTS

Ninety-seven (54%) of the patients used concomitant MTX, and 83 (46%) received either ETN monotherapy or used sDMARDs other than MTX. A significant correlation was noted between ETN dose and drug level [r = 0.45 (95% CI: 0.33-0.56)]. The ETN dose and serum drug level were correlated (p = 0.030) in both subgroups - in MTX group [r = 0.35 (95% CI: 0.14-0.52)] and in non-MTX group [r = 0.54 (95% CI: 0.39-0.67)].

CONCLUSION

In the present study, we found that concomitant MTX had no effect on serum ETN concentration or on clinical response. In addition, a significant correlation was detected between ETN dose and ETN concentration.

Disease control in patients with ankylosing spondylitis in real clinical practice in Spain: Results of the MIDAS study

INTRODUCTION AND OBJECTIVES

Understanding the disease activity is fundamental to improve patient prognosis and patients' quality of life. MiDAS study described disease activity in ankylosing spondylitis (AS) Spanish patients and the proportion of them with controlled disease.

METHODS

Observational, cross-sectional, multicenter study carried out under conditions of routine clinical practice. Adult (≥18 years) patients with ≥6 months since AS diagnosis treated ≥3 months prior to inclusion. The primary endpoint was the percentage of patients with low disease activity assessed through BASDAI (primary endpoint) and ASDAS-CRP (secondary endpoint).

RESULTS

313 AS patients included: 75.7% male; 78.5% HLA-B*27 positive; mean (SD) baseline age of 50.4 (12.0) years; mean (SD) disease duration of 15.5 (11.6) years; 73.5% were treated with biological disease-modifying antirheumatic drugs (DMARDs), 22.4% with non-biological DMARDs and 53.7% with non-steroidal anti-inflammatory drugs, alone or in combination. Monotherapy with biologics and non-biologics was used by 29.7% and 26.8% of patients, respectively. According to BASDAI, 38.0% were in remission (BASDAI≤2) and 64.5% showed adequate disease control (BASDAI<4). According to ASDAS-CRP, 29.4% achieved remission (ASDAS-CRP<1.3) and 28.1% low disease activity (1.3≤ASDAS-CRP<2.1).

CONCLUSIONS

Almost two thirds of the AS patients recruited had low disease activity, with about one third of them being in remission (BASDAI≤2, ASDAS-CRP<1.3). These results highlight the existing room for improvement in treating AS patients in clinical practice.

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.

Anti-TNFα drug levels in patients with rheumatoid arthritis and spondyloarthritis

BACKGROUND AND OBJECTIVES

Knowledge of the levels of anti-TNFa drugs can modify treatment in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA).

OBJECTIVES

To compare the levels of anti-TNFa in patients with RA vs SpA, in different clinical situations.

MATERIALS AND METHODS

A retrospective, observational study was conducted. Levels of anti-TNFa and the presence of anti-drug antibodies were measured in consecutively selected patients, using the ELISA technique.

RESULTS

Fifty-three, 73 and 78 patients treated with infliximab, adalimumab and etanercept were studied, respectively. The median drug levels in patients using standard doses were infliximab 2.2 µg/mL (1.4-5.2), adalimumab 4.9 µg/mL (0.8-8.9) and etanercept 3.1 µg/mL (2.3-4.4). There were no differences in drug levels according to disease activity but we found differences in etanercept and infliximab levels according to DMARD use.

CONCLUSIONS

Levels of anti-TNFa drugs will change with DMARD treatment.

Immunogenicity of subcutaneous TNF inhibitors and its clinical significance in real-life setting in patients with spondyloarthritis

KEY MESSAGES

Considerable proportion of patients with SpA have been immunized to the subcutaneous anti-TNF drug they are using. Concomitant use of MTX protects from immunization, whereas SASP does not. Patients with SpA using subcutaneous anti-TNF drugs can benefit from monitoring of the drug trough levels. Immunization to biological drugs can lead to decreased efficacy and increased risk of adverse effects. The objective of this cross-sectional study was to assess the extent and significance of immunization to subcutaneous tumor necrosis factor (TNF) inhibitors in axial spondyloarthritis (axSpA) patients in real-life setting. A serum sample was taken 1-2 days before the next drug injection. Drug trough concentrations, anti-drug antibodies (ADAb) and TNF-blocking capacity were measured in 273 patients with axSpA using subcutaneous anti-TNF drugs. The clinical activity of SpA was assessed using the Bath AS Disease Activity Index (BASDAI) and the Maastricht AS Entheses Score (MASES). ADAb were found in 11% of the 273 patients: in 21/99 (21%) of patients who used adalimumab, in 0/83 (0%) of those who used etanercept, in 2/79 (3%) of those who used golimumab and in 6/12 (50%) of those who used certolizumab pegol. Use of methotrexate reduced the risk of formation of ADAb, whereas sulfasalazine did not. Presence of ADAb resulted in decreased drug concentration and reduced TNF-blocking capacity. However, low levels of ADAb had no effect on TNF-blocking capacity and did not correlate with disease activity. The drug trough levels were below the consensus target level in 36% of the patients. High BMI correlated with low drug trough concentration. Patients with low drug trough levels had higher disease activity. The presence of anti-drug antibodies was associated with reduced drug trough levels, and the patients with low drug trough levels had higher disease activity. The drug trough levels were below target level in significant proportion of patients and, thus, measuring the drug concentration and ADAb could help to optimize the treatment in SpA patients.

Population Pharmacokinetics of Infliximab in Children with Juvenile Idiopathic Arthritis

BACKGROUND

The recommended infliximab (IFX) dose in (pediatric) rheumatology practice is 3-6 mg/kg every 4-8 weeks. Higher dosage regimens (>10 mg/kg) of IFX are effective and safe. To optimize IFX treatment in patients with juvenile idiopathic arthritis (JIA), therapeutic drug monitoring might be beneficial. To support routine therapeutic drug monitoring of IFX and regimen optimization for patients with JIA, in-depth knowledge of the pharmacokinetic (PK) variability of IFX is needed. As soon as the optimal therapeutic drug ranges are known, PK model-based simulation can be used to individualize drug dosing recommendations. In this study, a population PK model for IFX is described for patients with JIA.

METHODS

Data including IFX trough concentrations and anti-IFX antibodies of 27 pediatric patients with JIA on IFX maintenance treatment were retrieved from electronic charts. Three population PK models from the literature were validated for the authors' data set using the nonlinear mixed-effects modeling program NONMEM. A novel population PK model was developed based on the study data.

RESULTS

A total of 65 blood samples obtained after a median of 32 days after the last IFX infusion (interquartile range 28-42) were analyzed. The 3 published models underpredicted the observed trough concentrations. A newly developed one-compartment model best described the data corresponding to IFX serum concentration over time in patients with JIA.

CONCLUSIONS

This study shows a novel PK model for IFX in patients with JIA. The data show that different PK models are needed for different age categories (children or adults) and different diseases.

Therapeutic drug monitoring of biologics in inflammatory bowel disease: unmet needs and future perspectives

Therapeutic drug monitoring (TDM) has emerged as a useful tool for optimising the use of biologics, and in particular anti-tumour necrosis factor (anti-TNF) therapy, in inflammatory bowel disease (IBD). However, challenges remain and are hindering the widespread implementation of TDM in clinical practice. These barriers include identification of the optimal drug concentration to target, the lag time between sampling and results, and the proper interpretation of anti-drug antibody titres among different assays. Solutions to overcome these barriers include the harmonisation of TDM assays and the use of point-of-care testing. Other unmet needs include well designed prospective studies and randomised controlled trials focusing on proactive TDM, particularly during induction therapy. Future studies should also investigate the utility of TDM for biologics other than anti-TNF therapies in both IBD and other immune-mediated inflammatory diseases such as rheumatoid arthritis and psoriasis, and the use of pharmacokinetic modelling dashboards and pharmacogenetics towards individual personalised medicine.

Anti-TNFα Drug Levels in Patients with Rheumatoid Arthritis and Spondyloarthritis

BACKGROUND AND OBJECTIVES

Knowledge of the levels of anti-TNFα drugs can modify treatment in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA).

OBJECTIVES

To compare the levels of anti-TNFα in patients with RA vs SpA, in different clinical situations.

MATERIALS AND METHODS

A retrospective, observational study was conducted. Levels of anti-TNFα and the presence of anti-drug antibodies were measured in consecutively selected patients, using the ELISA technique.

RESULTS

Fifty-three, 73 and 78 patients treated with infliximab, adalimumab and etanercept were studied, respectively. The median drug levels in patients using standard doses were infliximab 2.2μg/ml (1.4-5.2), adalimumab 4.9μg/ml (0.8-8.9) and etanercept 3.1μg/ml (2.3-4.4). There were no differences in drug levels according to disease activity but we found differences in etanercept and infliximab levels according to DMARD use.

CONCLUSIONS

Levels of anti-TNFα drugs will change with DMARD treatment.

Therapeutic drug monitoring of anti-TNF drugs: an overview of applicability in daily clinical practice in the era of treatment with biologics in juvenile idiopathic arthritis (JIA)

BACKGROUND

Anti-tumor necrosis factor (TNF) drugs have improved the prognosis for juvenile idiopathic arthritis (JIA) significantly. However, evidence for individual treatment decisions based on serum anti-TNF drug levels and the presence of anti-drug antibodies (ADAbs) in children is scarce. We aimed to assess if anti-TNF drug levels and/or ADAbs influenced physician's treatment decisions in children with JIA.

METHODS

Patients' records in our center were retrospectively screened for measurements of anti-TNF drug levels and ADAbs in children with JIA using etanercept, adalimumab or infliximab. Clinical characteristics and disease activity were retrieved from patient charts.

RESULTS

We analyzed 142 measurements of anti-TNF drug levels in 65 children with JIA. Of these, ninety-seven (68.3%) were trough concentrations. N = 14/97 (14.4%) of these showed trough concentrations within the therapeutic drug range known for adults with RA and IBD. ADAbs against adalimumab were detected in seven patients and against infliximab in one patient. Seven (87,5%) of these ADAb-positive patients had non-detectable drug levels. A flowchart was made on decisions including rational dose escalation, stopping treatment in the presence of ADAbs and undetectable drug levels, showing that 45% of measurements influenced treatment decisions, which concerned 65% of patients (n = 42/65).

CONCLUSIONS

In the majority of patients, measurement of anti-TNF drug levels led to changes in treatment. A wide variation of anti-TNF drug levels was found possibly due to differences in drug clearance in different age groups. There is need for determination of therapeutic drug ranges and pharmacokinetic curves for anti-TNF and other biologics in children with JIA.

Drug Levels and Antibodies Against TNF-blockers in Spondyloarthritis and Rheumatoid Arthritis are Associated with the Activity but they do Not Predict it

BACKGROUND

Many patients may have resistance to TNF-blockers. These drugs may induce neutralizing antibodies. The determination of the drug levels of TNF-blockers and Anti-Drug Antibodies (ADAs) against TNF-blockers may help to make clinical decisions.

OBJECTIVES

The objective of this study was to associate and predict the drug levels of TNFblockers and ADAs in relation to disease activity in patients with Spondyloarthritis (SpA) and Rheumatoid Arthritis (RA).

METHODS

Cross-sectional study including patients fulfilling ASAS classification criteria for SpA and 2010 ACR-EULAR classification criteria for RA. These patients were treated with Adalimumab (ADA), Infliximab (IFX), and Etanercept (ETN). A bivariate analysis and the chi-square test were performed to evaluate the association of ADAs and drug levels with activity measures for SpA and RA. Five regression models analyzing drug levels, ADAs and disease activity measures using a multiple linear regression were performed in order to evaluate the prediction of ADAs and drug levels in relation to disease activity.

RESULTS

In SpA, IFX levels were associated with BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) (p=0.034). In RA, total drug levels were associated with DAS28-ESR (28 joint Disease activity Score-erythrocyte sedimentation rate), (p=0.008), DAS28-CRP (p=0.042), CDAI (Clinical Disease Activity Index) (p=0.047) and SDAI (Simple Disease activity index), (p=0.017). ADA levels had association with CDAI (p=0.002) and SDAI (p=0.002). IFX levels were associated with a DAS28-ESR (p=0.044), DAS28-CRP (p=0.022) and SDAI (p=0.022). ADAs were associated in SpA with BASDAI (p=0.027). Drug levels and ADAs did not predict disease activity in patients with SpA or RA.

CONCLUSION

ADAs and drug levels of anti-TNF are associated with disease activity measures in patients with SpA and RA. However, they cannot predict clinical activity in these conditions.

Assessment of Placental Disposition of Infliximab and Etanercept in Women With Autoimmune Diseases and in the Ex Vivo Perfused Placenta

Tumor necrosis factor (TNF) inhibitors are increasingly applied during pregnancy without clear knowledge of the impact on placenta and fetus. We assessed placental transfer and exposure to infliximab (n = 3) and etanercept (n = 3) in women with autoimmune diseases. Furthermore, we perfused healthy term placentas for 6 hours with 100 µg/mL infliximab (n = 4) or etanercept (n = 5). In pregnant women, infliximab transferred into cord blood but also entered the placenta (cord‐to‐maternal ratio of 1.6 ± 0.4, placenta‐to‐maternal ratio of 0.3 ± 0.1, n = 3). For etanercept, a cord‐to‐maternal ratio of 0.04 and placenta‐to‐maternal ratio of 0.03 was observed in one patient only. In ex vivo placenta perfusions, the extent of placental transfer did not differ between the drugs. Final concentrations in the fetal compartment for infliximab and etanercept were 0.3 ± 0.3 and 0.2 ± 0.2 µg/mL, respectively. However, in placental tissue, infliximab levels exceeded those of etanercept (19 ± 6 vs. 1 ± 3 µg/g, P < 0.001). In conclusion, tissue exposure to infliximab is higher than that of etanercept both in vivo as well as in ex vivo perfused placentas. However, initial placental transfer, as observed ex vivo, does not differ between infliximab and etanercept when administered in equal amounts. The difference in placental tissue exposure to infliximab and etanercept may be of clinical relevance and warrants further investigation. More specifically, we suggest that future studies should look into the occurrence of placental TNF inhibition and possible consequences thereof.

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.

Therapeutic drug monitoring with biologic agents in immune mediated inflammatory diseases

: Most exposure-response relationship studies show a positive correlation between biologic drug concentrations and favorable therapeutic outcomes in IMID with higher drug concentrations typically associated with more objective outcomes. Clinically, reactive TDM rationalizes the management of PNR and SLR to anti-tumor necrosis factor therapy and is emerging as the new standard of care in IBD as it is also more cost-effective than empiric dose escalation. Preliminary data suggest that proactive TDM with the goal to achieve a threshold drug concentration is associated with better therapeutic outcomes when compared to empiric drug optimization and/or reactive TDM of infliximab and adalimumab in IBD. However, more data from well-designed prospective studies are needed to prove the benefit of TDM-based algorithms in real life clinical practice in IMID.

Effective serum level of etanercept biosimilar and effect of antidrug antibodies on drug levels and clinical efficacy in Chinese patients with ankylosing spondylitis

OBJECTIVES

To investigate the effective serum level of etanercept biosimilar in Chinese patients with ankylosing spondylitis (AS) who achieve AS Disease Activity Score-C-reactive protein (ASDAS-CRP) < 2.1, and the effect of antidrug antibodies on drug levels and clinical efficacy.

METHODS

Our study enrolled 60 patients with AS who were treated with etanercept biosimilar. Serum and clinical data were collected at baseline and treatment weeks 4, 12, and 24. Drug levels and antidrug antibody levels were measured using an enzyme-linked immunosorbent assay while tumour necrosis factor (TNF)-α levels were measured using cytometric bead array. A receiver operating characteristic (ROC) curve was used to analyse effective serum level of etanercept biosimilar.

RESULTS

Patients with ASDAS-CRP ≥ 2.1 exhibited significantly lower drug levels than those with ASDAS-CRP < 2.1 did. The cut-off values of effective serum level of patients with AS who achieved ASDAS-CRP < 2.1 at weeks 4, 12, and 24 were 2.32, 2.12, and 2.36 μg/mL, respectively. Patients with drug levels above the cut-off value had lower Bath AS Disease Activity Index (BASDAI) and TNF-α levels. Antidrug antibodies had no effect on the Assessment of Spondylosis Arthritis International Society (ASAS) remission rates, but patients with antidrug antibodies had lower drug levels and higher TNF-α levels.

CONCLUSIONS

Detecting serum drug levels and antidrug antibody levels might facilitate estimation of the clinical efficacy and adjustment of medication regimen during etanercept biosimilar therapy in Chinese patients with AS.

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.

Adherence to etanercept therapy in rheumatoid arthritis patients during 3 years of follow-up

Objectives

To determine the percentage non-adherence to etanercept in patients with rheumatoid arthritis during three years of follow-up.

Methods

During study visits in this prospective cohort study, blood samples were taken to determine serum etanercept concentrations using ELISA and patients were asked if they had missed an etanercept dose, at which date and for what reason. Non-adherence was defined as serum etanercept concentration <0.1 μg/mL and no valid reason to miss the prescribed etanercept dose.

Results

In total, 292 consecutive patients treated with etanercept were included. Most patients had a valid reason to miss their etanercept dose (25/37). In total 12 out of 292 patients (4.1%, 95% confidence interval 2.2–7.2) were non-adherent during the 3 year period. In a small percentage of patients (3.4%, 95% confidence interval 0.8–10.4) who failed to respond to etanercept therapy, according to their rheumatologist, this was associated with inadequate exposure to etanercept and thus non-adherence.

Conclusion

In this study, adherence to etanercept therapy was measured using serum etanercept concentration. In most patients an absent etanercept concentration was due to a medical reason. Furthermore, the majority of patients were adherent to etanercept therapy and had adequate drug exposure. In total, only 12 out of 292 patients (4.1%) were non-adherent during 3 years of follow-up. These findings highlight that only a small minority of patients are non-adherent to etanercept treatment, especially compared to adherence rates of other drugs. However, physicians should be aware that in patients failing to respond to treatment, non-adherence is a possible cause.

Etanercept concentration and immunogenicity do not influence the response to Etanercept in patients with juvenile idiopathic arthritis

OBJECTIVE

To investigate the relationship of clinical response of Juvenile Idiopathic Arthritis (JIA) to etanercept (ETN) with ETN levels, and the presence of anti-drug antibodies to ETN (ADAb).

METHODS

Prospective study of JIA patients under 18 years old. Clinical and pharmacological data were collected at two visits. JIA clinical inactivity and activity were assessed according to the Wallace criteria and to the Juvenile Arthritis Disease Activity Score (JADAS). ETN and ADAb serum levels assessments were determined using ELISA-based assays.

RESULTS

126 patients were enrolled. The median duration of ETN treatment at inclusion was 569 days (range 53-2340). ADAb were undetectable (<10 ng/ml) in 171/218 (78%) samples and were > 25 ng/mL in 2/218 samples. No significant relationship between ETN concentration and the clinical inactivity status and JIA activity was found using either univariate logistic regression or multiple logistic regression analysis, adjusted on one individual descriptors, time since diagnosis, time of sampling, use of corticosteroids or methotrexate and classification of JIA. No correlation was found between the remission status and the detection of ADAb.

CONCLUSION

This study did not demonstrate any correlation between JIA activity and circulating ETN levels in a large population of patients with JIA previously treated with ETN for at least 1.5 months. As described for adults, our study confirms that ETN is marginally immunogenic in pediatric patients. These results do not support the clinical usefulness of a monitoring of ADAb or ETN concentrations for the management of this group of JIA patients if they fail to achieve clinical inactive disease.

Current Practice for Therapeutic Drug Monitoring of Biopharmaceuticals in Spondyloarthritis

Treatment of spondyloarthritis (SpA) has greatly improved in the biopharmaceutical era. These compounds, primarily tumor necrosis factor inhibitors, are effective, but some patients may show poor response, sometimes due to 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 practice, a tailored strategy based on drug monitoring is emerging as a way to improve the use of these drugs. However, the relevance of this therapeutic drug monitoring of biopharmaceuticals for SpA is still unknown. In this literature review, we examined the most relevant articles dealing with the concentration-response relation, ADA detection, and pharmacokinetics in SpA treated with biopharmaceuticals. ADAs were associated with low or undetectable concentration of monoclonal antibodies. The relation between drug concentration and clinical response in SpA is debated, some studies showing an association and others not. Therefore, therapeutic drug monitoring of biopharmaceuticals for SpA requires a better understanding of the association among the pharmacokinetics, pharmacodynamics, and immunogenicity of these drugs.

Intrapatient Variability in the Pharmacokinetics of Etanercept Maintenance Treatment

AIM

Etanercept has shown to mediate a favorable effect on immune-mediated inflammatory diseases (IMID), including plaque psoriasis. Therapeutic drug monitoring (TDM) of etanercept could improve clinical outcome and cost-effectiveness. A high intrapatient variability (IPV) of etanercept trough concentrations at standard dosing would reduce the feasibility of therapeutic drug monitoring. Studies have focused on the interpatient differences associated with the exposure to biologics. The aim of this study was to determine IPV of etanercept and correlate etanercept trough concentrations and IPV with treatment response.

METHODS

Repetitive serum samples of 29 psoriasis patients on standard etanercept maintenance treatment were collected. In these samples, etanercept trough concentrations were determined and IPV was assessed in relation to response to treatment.

RESULTS

The median IPV of etanercept trough concentrations was 33.7% (Q1 = 21.3% and Q3 = 51.7%) ranging from 8% to 155%. All 6 nonresponders showed an IPV at or above the median value of 33.7%. The 6 nonresponders showed a higher IPV as compared to the 23 responders (53.9% versus 24.2%; P = 0.031). The mean etanercept trough concentration for each patient ranged from 0.7 to 6.8 mcg/mL, with a median trough concentration of 2.7 mcg/mL. Patients with an IPV above the median had lower mean etanercept trough concentrations compared to patients with an IPV below the median (1.96 mcg/mL, 95% CI, 1.7-2.4 versus 3.2 mcg/mL, 95% CI, 2.7-4.0; P = 0.001).

CONCLUSIONS

The median IPV of etanercept trough concentrations in this study population was 33.7%. A higher IPV was correlated with lower etanercept trough concentrations and with nonresponsiveness. Prospective trials are required to demonstrate the value of adjusting the etanercept dose based on drug trough concentrations. The relatively high IPV observed in this study may complicate therapeutic drug monitoring.

Current Practice of Therapeutic Drug Monitoring of Biopharmaceuticals in Psoriasis Patients

The high prevalence of psoriasis and the high spending on pharmaceuticals motivate a more evidence-based and cost-effective usage of biopharmaceuticals. A growing body of evidence exists that the implementation of therapeutic drug monitoring for biopharmaceuticals in psoriasis patients optimizes patient management and clinical outcome and enhances their efficacy. Therefore, the aim of this review was to give an overview of the literature on therapeutic drug monitoring of biopharmaceuticals in the treatment of psoriasis and to provide the useful information to dermatologists to improve health care in psoriasis patients.

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.

Effect of Etanercept Concentration on Human Islet Integrity

BACKGROUND

Etanercept is widely used as an antiinflammatory drug to improve engraftment after intraportal islet transplantation. In contrast to other immunosuppressive agents, very little is known about detrimental effects of etanercept on islets. The aim of this pilot study was to define the toxic range of etanercept.

METHODS

Human islets isolated from 8 donors were cultured for 4-5 days at 37°C in culture medium supplemented with etanercept at concentrations from 2.5 to 40 μg/mL, corresponding to potential in vivo levels within the portal vein. After culture, islet equivalent (IEQ) yield, fragmentation index (islet number/IEQ), purity, viability, and stimulated insulin release (2 vs 20 mmol/L) were assessed and normalized to islets before culture.

RESULTS

Yield (73 ± 8%) and viability (91 ± 4%) were highest with 5 μg/mL etanercept. Islet loss was evident when etanercept was ≥10 μg/mL (55 ± 7%; P < .05 vs control). Fragmentation (154 ± 34%; P < .05) was markedly increased and viability (81 ± 4%, P < .05) markedly decreased with etanercept >10 μg/mL. The accumulation of cell debris at concentrations ≥20 μg/mL resulted in a significant reduction of islet purity (84 ± 3%; P < .05). Etanercept did not interfere with stimulated insulin secretion at concentrations ≤10 μg/mL. The maximum stimulation index was noted at 2.5 μg/mL (1.8 ± 0.1).

CONCLUSIONS

Etanercept is tolerated by isolated human islets at concentrations <10 μg/mL. Our data suggest that the tight range between benefit and toxicity should be considered for dosage and administration of etanercept.

Immunogenicity and loss of response to TNF inhibitors: implications for rheumatoid arthritis treatment

The availability of monoclonal antibodies has revolutionized the treatment of an increasingly broad spectrum of diseases. Inflammatory diseases are among those most widely treated with protein-based therapeutics, termed biologics. Following the first large-scale clinical trials with monoclonal antibodies performed in the 1990s by rheumatologists and clinical immunologists, the approval of these agents for use in daily clinical practice led to substantial progress in the treatment of rheumatic diseases. Despite this progress, however, only a proportion of patients achieve a long-term clinical response. Data on the use of agents blocking TNF, which were among the first biologics introduced into clinical practice, provide ample evidence of primary and secondary treatment inefficacy in patients with rheumatoid arthritis (RA). Important issues relevant to primary and secondary failure of these agents in RA include immunogenicity, methodological problems for the detection of antidrug antibodies and trough drug levels, and the implications for treatment strategies. Although there is no strong evidence to support the routine estimation of antidrug antibodies or serum trough levels during anti-TNF therapy, these assessments might be helpful in a few clinical situations; in particular, they might guide decisions on switching the therapeutic biologic in certain instances of secondary clinical failure.

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.

Potential Sources of Inter-Subject Variability in Monoclonal Antibody Pharmacokinetics

Understanding inter-subject variability in drug pharmacokinetics and pharmacodynamics is important to ensure that all patients attain suitable drug exposure to achieve efficacy and avoid toxicity. Inter-subject variability in the pharmacokinetics of therapeutic monoclonal antibodies (mAbs) is generally moderate to high; however, the factors responsible for the high inter-subject variability have not been comprehensively reviewed. In this review, the extent of inter-subject variability for mAb pharmacokinetics is presented and potential factors contributing to this variability are explored and summarised. Disease status, age, sex, ethnicity, body size, genetic polymorphisms, concomitant medication, co-morbidities, immune status and multiple other patient-specific details have been considered. The inter-subject variability for mAb pharmacokinetics most likely depends on the complex interplay of multiple factors. However, studies aimed at investigating the reasons for the inter-subject variability are sparse. Population pharmacokinetic models and physiologically based pharmacokinetic models are useful tools to identify important covariates, aiding in the understanding of factors contributing to inter-subject variability. Further understanding of inter-subject variability in pharmacokinetics should aid in development of dosing regimens that are more appropriate.

Comparison of drug survival and clinical outcome in patients with ankylosing spondylitis treated with etanercept or adalimumab

OBJECTIVE

To compare rates of drug survival and clinical response during 2 years of follow-up in ankylosing spondylitis (AS) patients treated with etanercept or adalimumab in routine care.

METHOD

Biological-naïve consecutive AS patients treated with etanercept (n = 163) or adalimumab (n = 82) were followed. Treatment discontinuation was due to inefficacy, adverse events, loss to follow-up, planning a pregnancy, or uveitis. Disease activity was assessed by the Ankylosing Spondylitis Disease Activity Score using C-reactive protein (ASDAS-CRP). Moderate disease activity was defined as an ASDAS-CRP < 2.1.

RESULTS

Twenty-seven patients (32.9%) treated with adalimumab and 30 (18.4%) with etanercept discontinued treatment. Cox regression analysis demonstrated a significant difference in survival rate between discontinuation of the drug in adalimumab patients compared with etanercept patients [hazard ratio (HR) 2.1, 95% confidence interval (CI) 1.3-4.5, p = 0.005; corrected for confounding factors: HR 2.5, 95% CI 1.3-4.5, p = 0.006]. There was no significant difference at 2 years of follow-up between the adalimumab- and the etanercept-treated patients in mean ± sd ASDAS-CRP (1.9 ± 1.1 and 2.0 ± 0.9, respectively, p = 0.624), and 23 out of 34 (67.6%) compared to 71 out of 117 (60.7%) reached ASDAS-CRP moderate disease activity (odds ratio 0.738, 95% CI 0.329-1.657, p = 0.530).

CONCLUSION

No significant difference was found between AS patients treated with etanercept and those treated with adalimumab in mean ASDAS-CRP and reaching ASDAS-CRP minimal disease activity at 2 year follow-up. Drug survival rate was higher in etanercept- compared to adalimumab-treated patients. However, this should be interpreted cautiously as the risk of allocation bias cannot be excluded.

Clinical utility of therapeutic drug monitoring in biological disease modifying anti-rheumatic drug treatment of rheumatic disorders: a systematic narrative review

INTRODUCTION

Biological Disease Modifying Anti-Rheumatic Drugs (bDMARDs) have improved the treatment outcomes of inflammatory rheumatic diseases including Rheumatoid Arthritis and spondyloarthropathies. Inter-individual variation exists in (maintenance of) response to bDMARDs. Therapeutic Drug Monitoring (TDM) of bDMARDs could potentially help in optimizing treatment for the individual patient. Areas covered: Evidence of clinical utility of TDM in bDMARD treatment is reviewed. Different clinical scenarios will be discussed, including: prediction of response after start of treatment, prediction of response to a next bDMARD in case of treatment failure of the first, prediction of successful dose reduction or discontinuation in case of low disease activity, prediction of response to dose-escalation in case of active disease and prediction of response to bDMARD in case of flare in disease activity. Expert opinion: The limited available evidence does often not report important outcomes for diagnostic studies, such as sensitivity and specificity. In most clinical relevant scenarios, predictive value of serum (anti-) drug levels is absent, therefore the use of TDM of bDMARDs cannot be advocated. Well-designed prospective studies should be done to further investigate the promising scenarios to determine the place of TDM in clinical practice.

Etanercept for treating axial spondyloarthritis

INTRODUCTION

Axial spondyloarthritis is an inflammatory rheumatic disease causing back pain, functional impairment and potential ankylosis in the advanced stage. In this context, TNF blockers have been a major therapeutic advance. Etanercept is a soluble recombinant TNF receptor fusion protein in this vain. Areas covered: The aim of this review is to summarize the current published data concerning the efficacy and tolerance of etanercept in axial spondyloarthrits. The authors performed a systematic review on PubMed, using 'etanercept' and 'spondyloarthritis', 'axial spondyloarthritis' or 'ankylosing spondylitis' keywords. Expert opinion: Etanercept showed clinical efficacy on the axial (non-radiographic and radiographic) and peripheral manifestations (peripheral arthritis and enthesitis) of axial spondyloarthritis (Ax-SpA). Among the extra-articular manifestations, it works on psoriasis but not on inflammatory bowel disease, with a lack of efficacy data in anterior uveitis. Etanercept also demonstrated an interesting tolerance profile and good drug survival rates after 5 years. Etanercept was also shown to reduce MRI inflammation on the spine and the sacroiliac joints. However, like other TNF blockers, its impact on radiographic progression could not be fully demonstrated. In the context of upcoming new biologic targeted treatments, head-to-head and longer-term randomized controlled trials are now required to further define the role of etanercept in spondyloarthritis treatment strategies.

New targets in psoriatic arthritis

PsA is an immune-mediated chronic inflammatory disease that affects both skin and joints; it is a heterogeneous disease characterized by synovitis, enthesitis, dactylitis and spondylitis. The impact on patients and the burden of disease are substantial. For assessment of the disease, patient-reported outcomes are increasingly important. Conventional therapy consists of NSAIDs, local and systemic CSs, and synthetic and biological DMARDs. While MTX, LEF, SSZ and CYC are the synthetic drugs mainly used, TNF-α blocking agents have represented the majority of biologics used in the last decade (infliximab, etanercept, adalimumab, certolizumab and golimumab). Treat-to-target strategies have been used successfully in PsA. This review concentrates on new developments, mainly covering biologic agents with an IL-17 inhibitor (secukinumab) and an anti-IL-23 agent (ustekinumab), but also synthetic drugs, including a novel phosphodiesterase-4 inhibitor (apremilast) and a Janus kinase inhibitor (tofacitinib) that blocks mainly Jak3 and Jak1 and, to a lesser extent, Jak2. The efficacy of some of these new agents may be even better for the skin than for the joints.

The association between etanercept serum concentration and psoriasis severity is highly age-dependent

The association between etanercept serum concentration and psoriasis disease severity is poorly investigated, and currently etanercept serum concentration monitoring that is aiming to optimize the psoriasis treatment lacks evidence. In this prospective study, we investigated the relation between etanercept exposure and disease severity via measuring etanercept concentrations at five consecutive time points in 56 psoriasis patients. Disease severity assessments included the Psoriasis Area and Severity Index (PASI), body surface area (BSA) and Physician Global Assessment (PGA), and etanercept and anti-etanercept antibody concentrations were determined every 3 months for a period of 1 year. The present study demonstrated that the association between etanercept concentration and psoriasis severity is age-dependent: when patients were stratified into three groups, patients in the youngest age group (-50 years) showed a lower PASI at a higher etanercept concentration (β = -0.26), whereas patients in the oldest age group (+59 years) showed the opposite trend (β =0.22). Similar age effects were observed in the relation of etanercept concentration with BSA (P=0.02) and PGA (P=0.02). The influence of age and length of time in therapy on the etanercept concentration-disease severity relation was unaffected by body mass index (BMI) or any other possible confounder. Incidence of anti-etanercept antibodies was low (2%). The age-dependent relation between etanercept serum concentrations is both unexpected and intriguing and needs further investigation.

The effectiveness of a real life dose reduction strategy for tumour necrosis factor inhibitors in ankylosing spondylitis and psoriatic arthritis

OBJECTIVE

To determine feasibility of TNF inhibitor (TNFi) dose reduction for severe AS and PsA patients.

METHODS

A retrospective study in a real-world setting. Criteria for dose reduction of TNFi included BASDAI < 4 for ⩾6 months in AS; or DAS28-ESR ⩽ 3.2 for ⩾6 months in PsA. TNFi dose was reduced by one-third. Patients who flared (BASDAI > 4 in AS or DAS28-ESR > 3.2 in PsA) were re-escalated to standard treatment dose.

RESULTS

Twenty-six per cent (33/125) of AS and 18% (15/83) of PsA patients fulfilled criteria and underwent TNFi dose reduction. Fifty-eight per cent (19/33) of AS and 60% (9/15) of PsA patients maintained TNFi dose reduction for mean (s.d) of 1.0 (0.8) years. Reinstating standard dose of TNFi recaptured low disease activity in all patients who failed dose reduction within 24 weeks, with no statistically significant difference in mean BASDAI compared with those maintaining TNFi dose reduction in AS at 24 weeks [mean (s.d) BASDAI 2.4 (1.1) vs 1.9 (1.5), respectively (P = 0.229)]; however in PsA, those who failed dose reduction had higher disease activity compared with patients maintained on TNFi dose reduction at 24 weeks [mean (s.d) DAS28-ESR 2.7 (0.6) vs 1.3 (0.5), respectively (P ⩽ 0.001)]. In PsA, a lower DAS28-ESR prior to dose reduction of TNFi was associated with more successful dose reduction.

CONCLUSIONS

In a real-world setting, 60% of individuals with severe AS and PsA who achieve low disease activity can successfully reduce the dose of TNFi therapy by a third for a mean of 1 year.

An update on the use of tumor necrosis factor alpha inhibitors in the treatment of ankylosing spondylitis

INTRODUCTION

Ankylosing spondylitis is a chronic immune-mediated disease affecting the sacroiliac joints and the spine manifesting with new bone formation and osteopenia. Over the past decade, tumour necrosis factor alpha (TNF-α) inhibitors (TNFi) have become the cornerstone for therapy in improving functional outcomes, and decreasing disease activity in patients with a marginal benefit from non-steroidal anti-inflammatory (NSAID) therapy. At this time, it remains to be determined whether these agents decrease new bone formation, although some studies have recently suggested that. Areas covered: In this review we discuss the factors that favour a good response to these agents both initially and during maintenance, and some of the more recent studies outlining strategies for dose reduction. Expert commentary: Finally, we discuss the importance of using more objective tools for disease activity, such as magnetic resonance imaging, as a complementary tool for clinical assessments in both predicting responses to treatment but also in selecting patients most suited for targeted therapy.

Clinical utility of random anti-tumor necrosis factor drug-level testing and measurement of antidrug antibodies on the long-term treatment response in rheumatoid arthritis

Objective

To investigate whether antidrug antibodies and/or drug non‐trough levels predict the long‐term treatment response in a large cohort of patients with rheumatoid arthritis (RA) treated with adalimumab or etanercept and to identify factors influencing antidrug antibody and drug levels to optimize future treatment decisions.

Methods

A total of 331 patients from an observational prospective cohort were selected (160 patients treated with adalimumab and 171 treated with etanercept). Antidrug antibody levels were measured by radioimmunoassay, and drug levels were measured by enzyme‐linked immunosorbent assay in 835 serial serum samples obtained 3, 6, and 12 months after initiation of therapy. The association between antidrug antibodies and drug non‐trough levels and the treatment response (change in the Disease Activity Score in 28 joints) was evaluated.

Results

Among patients who completed 12 months of followup, antidrug antibodies were detected in 24.8% of those receiving adalimumab (31 of 125) and in none of those receiving etanercept. At 3 months, antidrug antibody formation and low adalimumab levels were significant predictors of no response according to the European League Against Rheumatism (EULAR) criteria at 12 months (area under the receiver operating characteristic curve 0.71 [95% confidence interval (95% CI) 0.57, 0.85]). Antidrug antibody–positive patients received lower median dosages of methotrexate compared with antidrug antibody–negative patients (15 mg/week versus 20 mg/week; P = 0.01) and had a longer disease duration (14.0 versus 7.7 years; P = 0.03). The adalimumab level was the best predictor of change in the DAS28 at 12 months, after adjustment for confounders (regression coefficient 0.060 [95% CI 0.015, 0.10], P = 0.009). Etanercept levels were associated with the EULAR response at 12 months (regression coefficient 0.088 [95% CI 0.019, 0.16], P = 0.012); however, this difference was not significant after adjustment. A body mass index of ≥30 kg/m² and poor adherence were associated with lower drug levels.

Conclusion

Pharmacologic testing in anti–tumor necrosis factor–treated patients is clinically useful even in the absence of trough levels. At 3 months, antidrug antibodies and low adalimumab levels are significant predictors of no response according to the EULAR criteria at 12 months.

Influence of Immunogenicity on the Efficacy of Long-Term Treatment with TNF α Blockers in Rheumatoid Arthritis and Spondyloarthritis Patients

Objective. To analyze the clinical relevance of the levels of TNFα blockers and anti-drug antibodies (anti-drug Ab) in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) treated with adalimumab (ADA), etanercept (ETA), or infliximab (INF) for a prolonged period of time. Methods. Clinical characteristics (disease activity, and adverse events), serum TNFα blockers, and anti-drug Ab levels were evaluated in 62 RA and 81 SpA patients treated with TNFα blockers for a median of 28 months. Results. Anti-ADA Ab were detected in 1 (4.0%) and anti-INF Ab in 14 out of 57 (24.6%) RA and SpA patients. Patient with anti-ADA Ab and 57.1% patients with anti-INF Ab were considered nonresponders to treatment. Anti-ETA Ab were not found in any of 61 ETA treated patients. Anti-ADA and anti-INF Ab levels differ between responders and nonresponders (P > 0.05). Three (5.3%) patients with high serum anti-INF Ab levels developed infusion related reactions. Patients with anti-INF Ab more often required changing to another biologic drug (OR 11.43 (95% CI 1.08–120.93)) and treatment discontinuation (OR 9.28 (95% CI 1.64–52.52)). Conclusion. Patients not responding to treatment had higher serum anti-ADA and anti-INF Ab concentrations. Anti-INF Ab formation is related to increased risk of infusion related reactions, changing to another biologic drug, and treatment discontinuation.