Decreased clinical response to adalimumab in ankylosing spondylitis is associated with antibody formation

Pharmaceutical proteins at the interfaces and the role of albumin

A critical measure of the quality of pharmaceutical proteins is the preservation of native conformations of the active pharmaceutical ingredients. Denaturation of the active proteins in any step before administration into patients could lead to loss of potency and/or aggregation, which is associated with an increased risk of immunogenicity of the products. Interfacial stress enhances protein instability as their adsorption to the air-liquid and liquid-solid interfaces are implicated in the formation of denatured proteins and aggregates. While excipients in protein formulations have been employed to reduce the risk of aggregation, the roles of albumin as a stabilizer have not been reviewed from practical and theoretical standpoints. The amphiphilic nature of albumin makes it accumulate at the interfaces. In this review, we aim to bridge the knowledge gap between interfacial instability and the influence of albumin as a surface-active excipient in the context of reducing the immunogenicity risk of protein formulations.

Measurement of pre-treatment inflammatory cytokine levels is valuable for prediction of treatment efficacy to tumor necrosis factor inhibitor in axial spondyloarthritis patients

Aim

To evaluate the correlation of inflammatory cytokines with the treatment response to tumor necrosis factor inhibitor (TNFi) in axial spondyloarthritis (axSpA) patients.

Methods

This study enrolled 86 axSpA patients and 20 healthy controls (HCs). Inflammatory cytokines including tumor necrosis factor‐α (TNF‐α), interleukin (IL)‐1β, IL‐6, IL‐12, IL‐17A, IL‐21, IL‐23, and IL‐32 were determined in serum samples of axSpA patients before treatment and in HCs after enrollment. All patients received 40 mg adalimumab every 2 weeks for 12 weeks; meanwhile, ASAS40 (40 criteria of the Assessment by the SpondyloArthritis International Society) response rates were evaluated at weeks 2, 4, 8, and 12.

Results

Most inflammatory cytokines were elevated in axSpA patients compared with HCs (all P < 0.05) except for IL‐32 (P = 0.101). In axSpA patients, ASAS40 response rates were 0%, 19.5%, 34.5%, 47.1%, and 56.3% at weeks 0, 2, 4, 8, and 12, respectively. Baseline [interquartile range] IL‐6 (47.3 [32.5‐53.4] pg/mL vs 31.7 [23.0‐50.9] pg/mL, P = 0.005) and IL‐17A (127.9 [90.7‐149.5] pg/mL vs 96.6 [56.1‐112.6] pg/mL, P < 0.001) were higher in axSpA patients with ASAS40 response compared with those without ASAS40 response, while baseline TNF‐α, IL‐1β, IL‐12, IL‐21, IL‐23, and IL‐32 were not different between them (all P > 0.050). Multivariate logistic regression analysis disclosed that baseline IL‐17A (P = 0.037), C‐reactive protein (P = 0.012), and history of TNF inhibitor (P = 0.029) were independently associated with ASAS40 response. Furthermore, baseline IL‐17A, C‐reactive protein, history of TNFi, and their combination had an acceptable to good ability for predicting ASAS40 response.

Conclusion

Measurement of pre‐treatment inflammatory cytokine levels is valuable for predicting treatment efficacy of TNFi in axSpA patients.

A randomized, adaptive design, double-blind, 3-arm, parallel study assessing the pharmacokinetics and safety of AVT02, a high-concentration (100 mg/mL) adalimumab biosimilar, in healthy adult subjects (ALVOPAD FIRST)

BACKGROUND

This study (ALVOPAD FIRST) assessed bioequivalence, safety, and immunogenicity of AVT02, an adalimumab biosimilar, compared with reference product adalimumab (EU- and US-approved Humira®).

METHODS

Healthy subjects (N = 392) were randomized 1:1:1 to receive one 40 mg dose of AVT02, EU-reference product, or US-reference product subcutaneously. An interim analysis was planned when ~30 subjects per arm had completed the study, to optimize final sample size. The primary PK parameters were C_max, AUC_0-t, and AUC_0-inf. Bioequivalence was demonstrated if the 90% CI for the ratio of geometric means for the primary PK parameters were all contained within the prespecified margins of 80% and 125%. Safety and immunogenicity were assessed until Day 64.

RESULTS

The 90% CI for the ratio of geometric means for the primary PK parameters, based on Fisher's Combination test analysis, were all contained within the prespecified bioequivalence margins of 80% and 125%, supporting the demonstration of bioequivalence between AVT02 and both EU- and US-reference product. The safety and immunogenicity profiles were comparable across all three treatment arms.

CONCLUSION

PK bioequivalence was supported between AVT02, US-licensed- and EU-approved-reference product adalimumab. Similar safety and immunogenicity were also demonstrated.

TRIAL REGISTRATION

The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT03849313).

Adalimumab for CNS sarcoidosis: single-center experience and literature review

BACKGROUND

Tumor necrosis factor (TNF) alpha is critical in the development of granulomas and multiple recent reports have highlighted the role of infliximab, an infused TNF alpha inhibitor, in the treatment of neurosarcoidosis. As a self-injected TNF alpha inhibitor, adalimumab has certain advantages over infused medications, including greater patient freedom and autonomy. Experience with adalimumab is not well reported in the literature.

OBJECTIVE

To report clinical experience with adalimumab in the treatment of central nervous system (CNS) sarcoidosis by combining observations in our center with those that have been reported in the literature.

METHODS

Patients were identified from the Mass General Brigham Research Patient Data Registry and in the literature by searching PubMed. Patients with CNS manifestations of sarcoidosis treated with adalimumab were included for retrospective review and analyzed for baseline characteristics, treatment indications, outcomes, and adverse effects.

RESULTS

Adalimumab was commonly started after failure of or intolerance to infliximab and methotrexate. Of those with adequate follow-up, 5/10 ultimately improved, remission was maintained in 3/10, and 2/10 with active disease remained stable without further worsening. One patient suffered a relapse, likely multifactorial in etiology, but has remained relapse free on adalimumab for 10 months subsequently. Three patients ultimately discontinued adalimumab.

CONCLUSIONS

Preliminary evidence suggests that adalimumab may be a reasonable therapeutic option for patients with neurosarcoidosis affecting the CNS, including those with medically refractory disease.

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.

Abstract

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.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00296-021-04955-8.

Immunogenicity of antitumor necrosis factor therapy in patients with spondyloarthritis

Objectives To evaluate the serum dosage of the biomedicine (DBM) and the incidence of antidrug antibody (ADA) against antitumor necrosis factor (TNF) in spondyloarthritis, and to demonstrate the influence of these parameters on the clinical efficiency. Methods We conducted a cross-sectional multicentric study including patients with spondylarthritis (SpA) under antiTNF (infliximab [INF], etanercept [ETA] and adalimumab [ADL]) for at least 6 months. A dosage of the ADA and DBM were practiced by the immuno-enzymatic essay. Result Seventy one patients were recruited. Disease modifying antirheumatic drugs (DMARDs) were associated with anti-TNF in 30%. ADA was positive in 54% for INF, 33% for ADL and 0% for ETA with a significant difference(p<0.0001). Immunogenicity was correlated to a bad therapeutic response (Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]≥4)(p=0.04). The DBM was inversely correlated with the rate of ADA for patients treated with INF(p<0.0001) and ADL(p<0.0001). The DBM was also inversely correlated with BASDAI of INF(p=0.03) and ADL (p=0.01). ADA was significantly associated with an anterior switch of anti TNF(p=0.04), the use of INF(p=0.002), presence of coxitis(p=0.01) and higher body mass index (BMI)(p=0.007). DMARDs associated with anti TNF were not a protective factor for positive ADA. In a multivariate study, only INF and BMI were independent factors of positive ADA. Conclusion The ADA formation lowered the DBM and favored the therapeutic failure.

Immunogenicity-unwanted immune responses to biological drugs - can we predict them?

INTRODUCTION

Biological agents (BAs) target molecules involved in disease mechanisms and have modified the natural history of several immune-mediated disorders. All BAs are immunogenic, resulting in the formation of antidrug antibodies (ADAs), which can neutralize drug activity leading to loss of response and potential relapse, or serious adverse events such as infusion hypersensitivity reactions. The production of ADAs is the result of a specific adaptive immune response in which T and B cells are involved.

AREAS COVERED

Factors conditioning the immunogenicity of BAs, including drug-, treatment- and patient-related factors are currently the subject of many studies. Among them, a lot of attention is dedicated to define the impact of BAs structure, the effect of targeting (soluble or membrane) molecules, the impact of interruption of therapy as well as the role of genetic (HLA and non-HLA) predisposing factors and disease activity.

EXPERT OPINION

Knowledge of factors capable of influencing the immunogenicity of BAs may help to understand, in a predictive manner and at the single patient level, the presence of risk factors influencing the production of ADAs and their impact on clinical outcomes.

In vitro human helper T-cell assay to screen antibody drug candidates for immunogenicity

Monoclonal antibody (mAb) drugs offer a number of valuable treatments. Many newly developed mAb drugs include artificial modification of amino acid sequences from human origin, which may cause higher immunogenicity to induce anti-drug antibodies (ADA). If the immunogenicity of a new candidate can be understood in the nonclinical phase, clinical studies will be safer and the success rate of development improved. Empirically, in vitro immunogenicity assays with human cells have proved to be sufficiently sensitive to nonhuman proteins, but not to human/humanized mAb. To detect the weaker immunogenicity of human-based mAb, a more sensitive biomarker for in vitro assays is needed. The in vitro study here developed a proliferation assay (T_H cell assay) using flow cytometry analysis that can detect a slight increase in proliferating T_H cells. Samples from 218 donors treated with a low-immunogenic drug (etanercept) were measured to determine a positive threshold level. With this threshold, positive donor percentages among PBMC after treatment with higher-immunogenicity mAb drugs were noted, that is, 39.5% with humanized anti-human A33 antibody (hA33), 27.3% with abciximab, 25.9% with adalimumab, and 14.8% with infliximab. Biotherapeutics with low immunogenicity yielded values of 0% for basiliximab and 3.7% for etanercept. These data showed a good comparability with previously reported incidences of clinical ADA with the evaluated drugs. Calculations based on the data here showed that a T_H cell assay with 40 donors could provide statistically significant differences when comparing low- (etanercept) versus highly immunogenic mAb (except for infliximab). Based on the outcomes here, for screening purposes, a practical cutoff point of 3/20 positives with 20 donors was proposed to alert immunogenicity of mAb drug candidates.

Methotrexate effect on immunogenicity and long-term maintenance of adalimumab in axial spondyloarthritis: a multicentric randomised trial

Objectives

Anti-drug antibodies (ADA) are responsible for decreased adalimumab efficacy in axial spondyloarthritis (SpA). We aimed to evaluate the ability of methotrexate (MTX) to decrease adalimumab immunisation.

Methods

A total of 110 patients eligible to receive adalimumab 40 mg subcutaneously (s.c.) every other week were randomised (1:1 ratio) to receive, 2 weeks before adalimumab (W-2) and weekly, MTX 10 mg s.c. (MTX+) or not (MTX−). ADA detection and adalimumab serum concentration were assessed at weeks 4 (W4), 8 (W8), 12 (W12) and 26 (W26) after starting adalimumab (W0). The primary outcome was the proportion of patients with ADA at W26. Four years after the study completion, we retrospectively analysed adalimumab maintenance in relation with MTX co-treatment duration.

Results

We analysed data for 107 patients (MTX+; n=52; MTX-; n=55). ADA were detected at W26 in 39/107 (36.4%) patients: 13/52 (25%) in the MTX+ group and 26/55 (47.3%) in the MTX− group (p=0.03). Adalimumab concentration was significantly higher in the MTX+ than MTX− group at W4, W8, W12 and W26. The two groups did not differ in adverse events or efficacy. In the follow-up study, MTX co-treatment >W26 versus no MTX or ≤W26 was significantly associated with adalimumab long-term maintenance (p=0.04).

Conclusion

MTX reduces the immunogenicity and ameliorate the pharmacokinetics of adalimumab in axial SpA. A prolonged co-treatment of MTX>W26 seems to increase adalimumab long-term maintenance.

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.

Factors associated with ASDAS remission in a long-term study of ankylosing spondylitis patients under tumor necrosis factor inhibitors

OBJECTIVE

To determine the clinical and demographic factors associated with disease remission and drug survival in patients with ankylosing spondylitis (AS) on TNF inhibitors.

METHODS

Data from a longitudinal electronic database of AS patients under anti-TNF therapy between June/2004 and August/2013. Demographic, clinical parameters, disease activity by ASDAS remission (< 1.3) and inactive/low (< 2.1) were analyzed to characterize reasons for drug survival and switching of anti-TNF.

RESULTS

Among 117 AS patients, 69 (59%) were prescribed only one anti-TNF, 48 (41%) switched to a second anti-TNF and 13 (11%) to a third anti-TNF. Considering ASDAS-CRP < 1.3, 31 (39%) patients were inactive at the end of the study. Non-switchers (P = 0.04), younger age (P = 0.004), non-smoking (P = 0.016), shorter disease duration (P = 0.047), more frequent use of SSZ (P = 0.037) and lower BASDAI (P = 0.027), BASMI (P = 0.034) and BASFI (P = 0.003) at baseline were associated with remission. In the multivariate analysis younger age (P = 0.016) and lower BASDAI (P = 0.032) remained as remission predictors.

CONCLUSION

This study supports that ASDAS-CRP remission is an achievable goal not only for non-switchers but also for second anti-TNF, particularly in patients with younger age and lower BASDAI at baseline. Co-medication and non-smoker status seems to have a beneficial effect in anti-TNF response in this population.

Immunoassay methods used in clinical studies for the detection of anti-drug antibodies to adalimumab and infliximab

We examined the assay formats used to detect anti-drug antibodies (ADA) in clinical studies of the anti-tumour necrosis factor (TNF) monoclonal antibodies adalimumab and infliximab in chronic inflammatory disease and their potential impact on pharmacokinetic and clinical outcomes. Using findings of a recent systematic literature review of the immunogenicity of 11 biological/biosimilar agents, we conducted an ancillary qualitative review of a subset of randomized controlled trials and observational studies of the monoclonal antibodies against anti-TNF factor adalimumab and infliximab. Among studies of adalimumab and infliximab, the immunoassay method used to detect antibodies was reported in 91 of 111 (82%) and 154 of 206 (75%) adalimumab and infliximab studies, respectively. In most adalimumab and infliximab studies, an enzyme-linked immunosorbent assay or radioimmunoassay was used [85 of 91 (93%) and 134 of 154 (87%), respectively]. ADA incidence varied widely among assays and inflammatory diseases (adalimumab, 0-87%; infliximab, 0-79%). Pharmacokinetic and clinical outcomes were only reported for ADA-positive patients in 38 of 91 (42%) and 61 of 154 (40%) adalimumab and infliximab studies, respectively. Regardless of assay format or biological used, ADA formation was associated with lower serum concentrations, reduced efficacy and elevated rates of infusion-related reactions. Consistent with previous recommendations to improve interpretation of immunogenicity data for biologicals, greater consistency in reporting of assay methods and clinical consequences of ADA formation may prove useful. Additional standardization in immunogenicity testing and reporting, application of modern, robust assays that satisfy current regulatory expectations and implementation of international standards for marketed products may help to improve our understanding of the impact of immunogenicity to biologics.

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.

Secukinumab Demonstrates Significantly Lower Immunogenicity Potential Compared to Ixekizumab

Introduction

Secukinumab, a fully human monoclonal antibody that selectively neutralizes IL-17A, has been shown to have significant efficacy in the treatment of moderate to severe plaque psoriasis (PsO) and psoriatic arthritis (PsA), demonstrating a rapid onset of action and sustained responses with a favorable safety profile. All biotherapeutics, including monoclonal antibodies (mAbs), can be immunogenic, leading to formation of anti-drug antibodies (ADAs) that can result in loss of response and adverse events such as hypersensitivity reactions. Thus, the immunogenicity potential of biotherapeutics is of particular interest for physicians. Of the 2842 patients receiving secukinumab across six phase 3 psoriasis clinical trials, only 0.4% developed treatment-emergent ADAs over 3 years of treatment. Direct comparison of clinical immunogenicity incidence rates is hampered by the nature of clinical immunogenicity assays, differences in study designs, patient populations, and treatment regimens.

Methods

We evaluated side-by-side in the same healthy donors two recently approved IL-17A selective antibodies, secukinumab and ixekizumab, along with adalimumab and ustekinumab, for their capacity to induce anti-drug related T cell responses in vitro and estimated their potential for developing ADAs in patients.

Results

We found that healthy donors show both significantly less frequent T cell responses and lower numbers of pre-existing T cells to secukinumab than to ixekizumab and adalimumab. Although there was a tendency for a lower response to ustekinumab, this difference was not significant.

Conclusion

In summary, this in vitro study confirms the significantly lower immunogenicity potential and provides an explanation for the lower clinical immunogenicity incidence found for secukinumab in comparison to other approved therapeutic antibodies used to treat plaque psoriasis.

Funding

Novartis Pharmaceuticals AG.

Electronic supplementary material

The online version of this article (10.1007/s13555-018-0220-y) contains supplementary material, which is available to authorized users.

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.

Reprint of "Anti-therapeutic antibodies and their clinical impact in patients treated with the TNF antagonist adalimumab"

Patients treated with the TNF antagonist adalimumab develop anti-therapeutic antibodies (ATA), the prevalence of which varies depending on the assay used. Most assays are compromised due to the presence of adalimumab in the clinical samples. Our objective was to develop an antibody assay, applicable for clinical testing, which overcomes the limitation of therapeutic interference and to further determine the relationship between ATA development, adalimumab levels and disease activity in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) or ankylosing spondylitis (AS). Use of an electrochemiluminescence platform permitted development of fit-for-purpose immunoassays. Serum samples from patients, taken prior to and at 12 and 24 weeks of treatment, were retrospectively analysed for levels of adalimumab and ATA. Overall, the antibody prevalence was 43.6% at 12 weeks and 41% at 24 weeks of treatment. Disruption of immune complexes by acid dissociation, a strategy often adopted for this purpose, only marginally increased the antibody prevalence to 48.7% and 46% at 12 and 24 weeks respectively. We found that antibody formation was associated with decreasing levels of circulating adalimumab, but no direct effect on disease activity was evident as assessed using DAS28 for RA patients and BASDAI for PsA and AS patients. However, a negative correlation of free adalimumab trough levels with disease activity scores was observed. Data showed that adalimumab levels can serve as an indicator of ATA development which can then be confirmed by ATA testing. Monitoring of both therapeutic and antibodies should be considered during adalimumab therapy to allow clinicians to personalise treatments for maximal therapeutic outcomes.

Immunogenicity of Biologics in Chronic Inflammatory Diseases: A Systematic Review

OBJECTIVES

A systematic review was conducted to explore the immunogenicity of biologic agents across inflammatory diseases and its potential impact on efficacy/safety.

METHODS

Literature searches were conducted through November 2016 to identify controlled and observational studies of biologics/biosimilars administered for treatment of rheumatoid arthritis (RA), psoriatic arthritis (PsA), juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), non-radiographic axial spondyloarthritis (nr-axSpA), psoriasis (Ps), Crohn's disease, and ulcerative colitis.

RESULTS

Of >21,000 screened publications, 443 were included. Anti-drug antibody (ADAb) rates varied widely among biologics across diseases (and are not directly comparable because of immunoassay heterogeneity); the highest overall rates were reported with infliximab (0-83%), adalimumab (0-54%), and infliximab biosimilar CT-P13 (21-52%), and the lowest with secukinumab (0-1%), ustekinumab (1-11%), etanercept (0-13%), and golimumab (0-19%). Most ADAbs were neutralizing, except those to abatacept and etanercept. ADAb+ versus ADAb- patients had lower rates of clinical response to adalimumab (RA, PsA, JIA, AS, Ps), golimumab (RA), infliximab (RA, PsA, AS, Ps), rituximab (RA), ustekinumab (Ps), and CT-P13 (RA, AS). Higher rates of infusion-related reactions were reported in infliximab- and CT-P13-treated ADAb+ patients. Background immunosuppressives/anti-proliferatives reduced biologic immunogenicity across diseases.

CONCLUSIONS

Based on reviewed reports, biologic/biosimilar immunogenicity differs among agents, with the highest rates observed with infliximab and adalimumab. As ADAb formation in biologic-/biosimilar-treated patients may increase the risk of lost response, the immunogenicity of these agents is an important (albeit not the only) consideration in the treatment decision-making process.

Anti-therapeutic antibodies and their clinical impact in patients treated with the TNF antagonist adalimumab

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ECL-based assays for measurement of adalimumab and adalimumab antibodies.

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Performance of ECL antibody assay not significantly improved by acid dissociation.

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Negative correlation between levels of antibody and free adalimumab.

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Negative correlation between adalimumab level and disease activity scores.

Patients treated with the TNF antagonist adalimumab develop anti-therapeutic antibodies (ATA), the prevalence of which varies depending on the assay used. Most assays are compromised due to the presence of adalimumab in the clinical samples. Our objective was to develop an antibody assay, applicable for clinical testing, which overcomes the limitation of therapeutic interference and to further determine the relationship between ATA development, adalimumab levels and disease activity in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) or ankylosing spondylitis (AS). Use of an electrochemiluminescence platform permitted development of fit-for-purpose immunoassays. Serum samples from patients, taken prior to and at 12 and 24 weeks of treatment, were retrospectively analysed for levels of adalimumab and ATA. Overall, the antibody prevalence was 43.6% at 12 weeks and 41% at 24 weeks of treatment. Disruption of immune complexes by acid dissociation, a strategy often adopted for this purpose, only marginally increased the antibody prevalence to 48.7% and 46% at 12 and 24 weeks respectively. We found that antibody formation was associated with decreasing levels of circulating adalimumab, but no direct effect on disease activity was evident as assessed using DAS28 for RA patients and BASDAI for PsA and AS patients. However, a negative correlation of free adalimumab trough levels with disease activity scores was observed. Data showed that adalimumab levels can serve as an indicator of ATA development which can then be confirmed by ATA testing. Monitoring of both therapeutic and antibodies should be considered during adalimumab therapy to allow clinicians to personalise treatments for maximal therapeutic outcomes.

Higher body mass index and anti-drug antibodies predict the discontinuation of anti-TNF agents in Korean patients with axial spondyloarthritis

OBJECTIVE

The development of anti-drug antibodies against tumor necrosis factor inhibitors is a likely explanation for the failure of TNF-inhibitors in patients with spondyloarthritis. Our study determined the existence and clinical implications of ADAbs in axial spondyloarthritis patients.

METHODS

According to the Assessment of SpondyloArthritis International Society classification criteria for axial spondyloarthritis, patients treated with adalimumab or infliximab were recruited consecutively. Serum samples were collected at enrollment to measure anti-drug antibodies and drug levels.

RESULTS

Of 100 patients, the mean duration of current TNF inhibitor use was 22.3±17.9 months. Anti-drug antibodies were detected in 5 of 72 adalimumab users compared to 5 of 28 infliximab users (6.9% vs. 17.9%). Anti-drug antibodies-positive patients had a significantly higher body mass index than anti-drug antibodies-negative patients among both adalimumab (28.4±5.9kg/m² vs. 24.3±2.9kg/m², respectively, p=0.01) and infliximab users (25.9±2.8kg/m² vs. 22.6±2.8kg/m², respectively, p=0.02). During the median 15-month follow-up period, drug discontinuation occurred more frequently in the anti-drug antibodies-positive group than the anti-drug antibodies-negative group (30.0% vs. 6.5%, respectively, p=0.04). In logistic regression, anti-drug antibodies positivity (OR=5.85, 95% CI 1.19-28.61, p=0.029) and body mass index (OR=4.35, 95% CI 1.01-18.69, p=0.048) were associated with a greater risk of stopping TNF inhibitor treatment.

CONCLUSIONS

Our result suggests that the presence of anti-drug antibodies against adalimumab and infliximab as well as a higher body mass index can predict subsequent drug discontinuation in axial spondyloarthritis patients.

Higher body mass index and anti-drug antibodies predict the discontinuation of anti-TNF agents in Korean patients with axial spondyloarthritis

OBJECTIVE

The development of anti-drug antibodies (ADAbs) against tumor necrosis factor (TNF) inhibitors is a likely explanation for the failure of TNF-inhibitors in patients with spondyloarthritis (SpA). Our study determined the existence and clinical implications of ADAbs in axial SpA patients.

METHODS

According to the Assessment of SpondyloArthritis International Society classification criteria for axial SpA, patients treated with adalimumab or infliximab were recruited consecutively. Serum samples were collected at enrollment to measure ADAb and drug levels.

RESULTS

Of 100 patients, the mean duration of current TNF inhibitor use was 22.3±17.9 months. ADAbs were detected in 5 of 72 adalimumab users compared to 5 of 28 infliximab users (6.9% vs. 17.9%). ADAb-positive patients had a significantly higher body mass index than ADAb-negative patients among both adalimumab (28.4±5.9kg/m2 vs. 24.3±2.9kg/m2, respectively, p=0.01) and infliximab users (25.9±2.8kg/m2 vs. 22.6±2.8kg/m2, respectively, p=0.02). During the median 15-month follow-up period, drug discontinuation occurred more frequently in the ADAb-positive group than the ADAb-negative group (30.0% vs. 6.5%, respectively, p=0.04). In logistic regression, ADAb positivity (OR=5.85, 95% CI 1.19-28.61, p=0.029) and BMI (OR=4.35, 95% CI 1.01-18.69, p=0.048) were associated with a greater risk of stopping TNF inhibitor treatment.

CONCLUSIONS

Our result suggests that the presence of ADAbs against adalimumab and infliximab as well as a higher BMI can predict subsequent drug discontinuation in axial SpA patients.

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.

Immunogenicity of Recombinant Human Interferon Beta-1b in Immune-Tolerant Transgenic Mice Corresponds with the Biophysical Characteristics of Aggregates

Determining to what extent biophysical characteristics of aggregates affect immunogenicity of therapeutic interferon beta-1b. Three recombinant human interferon beta-1b (rhIFNβ-1b) samples with different levels of aggregates generated by copper oxidation, thermal stress, or left untreated, as well as Avonex(®) drug substance and Betaferon(®) drug product, were injected intraperitoneally in nontransgenic and interferon beta transgenic FVB/N mice 5 times per week for 3 weeks. Antibodies against interferon beta were measured using enzyme-linked immunosorbent assay. UV and fluorescence spectroscopy, dynamic light scattering, size exclusion chromatography, reversed-phase high-performance liquid chromatography (RP-HPLC), fluid imaging microscopy, and resonant mass measurement, as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting, were used to characterize and quantitate aggregates in the 3 rhIFNβ preparations, to correlate biophysical characteristics with immunogenicity. In immune-tolerant interferon beta transgenic FVB/N mice, Betaferon drug product showed the highest immunogenicity, while Avonex drug substance showed the lowest level of immunogenicity. Of the 3 forms of rhIFNβ-1b, copper-oxidized rhIFNβ-1b showed lower immunogenicity than thermally stressed rhIFNβ-1b, despite containing larger aggregates. Both copper-oxidized rhIFNβ-1b and thermally stressed rhIFNβ-1b exhibited changes in protein structure as shown using fluorescence spectroscopy and RP-HPLC. Nontransgenic, nonimmune-tolerant FVB/N mice generated high antibody titers against all interferon beta samples tested. The level of immunogenicity and the breaking of tolerance in FVB/N transgenic mice are not only related to the level of aggregation but also depend on the size and structure of the aggregates.

Secukinumab, a novel anti-IL-17A antibody, shows low immunogenicity potential in human in vitro assays comparable to other marketed biotherapeutics with low clinical immunogenicity

Secukinumab is a human monoclonal antibody that selectively targets interleukin-17A and has been demonstrated to be highly efficacious in the treatment of moderate to severe plaque psoriasis, starting at early time points, with a sustained effect and a favorable safety profile. Biotherapeutics--including monoclonal antibodies (mAbs)--can be immunogenic, leading to formation of anti-drug antibodies (ADAs) that can result in unwanted effects, including hypersensitivity reactions or compromised therapeutic efficacy. To gain insight into possible explanations for the clinically observed low immunogenicity of secukinumab, we evaluated its immunogenicity potential by applying 2 different in vitro assays: T-cell activation and major histocompatibility complex-associated peptide proteomics (MAPPs). For both assays, monocyte-derived dendritic cells (DCs) from healthy donors were exposed in vitro to biotherapeutic proteins. DCs naturally process proteins and present the derived peptides in the context of human leukocyte antigen (HLA)-class II. HLA-DR-associated biotherapeutic-derived peptides, representing potential T-cell epitopes, were identified in the MAPPs assay. In the T-cell assay, autologous CD4(+) T cells were co-cultured with secukinumab-exposed DCs and T-cell activation was measured by proliferation and interleukin-2 secretion. In the MAPPs analysis and T-cell activation assays, secukinumab consistently showed relatively low numbers of potential T-cell epitopes and low T-cell response rates, respectively, comparable to other biotherapeutics with known low clinical immunogenicity. In contrast, biotherapeutics with elevated clinical immunogenicity rates showed increased numbers of potential T-cell epitopes and increased T-cell response rates in T-cell activation assays, indicating an approximate correlation between in vitro assay results and clinical immunogenicity incidence.

Indirect assessment of neutralizing anti-drug antibodies utilizing pharmacokinetic assay data

Neutralizing anti-drug antibodies (NAbs) can adversely impact efficacy and safety of biologic therapeutics. However, current assay formats to detect NAbs are limited in their use during the dosing phase due to interference by circulating drug, resulting in low drug tolerance. To improve the drug tolerance for NAb detection, an alternative approach for indirect NAb (iNAb) assessment was developed and qualified that uses a combination of pharmacokinetic (PK) assays to measure the serum concentrations of free and total drug. It is demonstrated that the ratio of free to total drug concentrations, referred to as F/T ratio, is a novel PK parameter that can indicate neutralizing activity in test samples. The iNAb assessment correctly identified NAb-positive samples with high drug concentrations that led to false negative results in a conventional NAb assay. Moreover, iNAb reliably distinguished between NAbs and non-neutralizing anti-drug antibodies over a wide range of concentrations. A proposal on how to deploy iNAb assessment within a broader immunogenicity testing strategy is presented.

The clinical relevance of early anti-adalimumab antibodies detection in rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis: A prospective multicentre study

OBJECTIVES

To evaluate the relevance of anti-adalimumab (anti-ADA) antibodies (Abs) and their relationship with clinical/laboratory features in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA).

METHODS

Fifty-eight patients affected with RA, AS and PsA were prospectively enrolled. Clinical/laboratory characteristics, disease activity, anti-ADA, anti-nuclear (ANA), anti-double strand (ds)DNA, anti-extractable nuclear antigens (anti-ENA) and anti-phospholipid Abs (aPL) were evaluated at baseline, 4, 12 and 24 weeks of adalimumab treatment.

RESULTS

Anti-ADA Abs were observed in 11/58 (19%) patients; they were detected within the 4th week of therapy in 90.9% of the positive subjects. Anti-ADA positivity was associated with significantly lower mean adalimumab serum levels (P<0.05). Treatment failure was observed in 20/58 (34.5%) patients and was significantly associated with anti-ADA Abs (P<0.05). Mean adalimumab serum levels were significantly lower in patients with treatment failure than in the responders one, both in the whole cohort (P<0.01) and in the group of anti-ADA positive patients (P<0.01). Adverse events happened more often in anti-ADA positive then in anti-ADA negative patients (27.3% vs 14.9%).

CONCLUSIONS

Anti-ADA abs could be considered an early marker associated to a poor clinical response to adalimumab treatment. Routine ANA/anti-ENA/aPL monitoring did not reveal as useful tools to predict the development of anti-ADA abs.

Immunogenicity of anti-TNF biologic agents in the treatment of rheumatoid arthritis

INTRODUCTION

The use of biologic disease-modifying anti-rheumatic drugs (DMARDs), including therapeutic antibodies, antibody fragments and protein constructs that target key mediators in the pathophysiology of rheumatoid arthritis (RA), has improved the chance of achieving low disease activity and clinical remission. However, individual patients respond differently to biologic DMARD therapy, particularly the tumor necrosis factor (TNF) inhibitors.

AREAS COVERED

While the variation of clinical response may be related to pharmacogenetic and other unknown factors, immunogenicity associated with some of these agents may contribute in part to a lack of efficacy and immune-mediated side effects. Timely detection of immunogenicity may avoid continued administration of ineffective treatment, and reduce unnecessary risks and costs. Access to and appropriate implementation of clinically validated drug level assays is required.

EXPERT OPINION

There are currently no evidence-based recommendations to guide biologic therapy on the basis of drug level and immunogenicity testing but as more data become available and better tests are developed, a strategy of immunopharmacologic guidance to individualize treatment of RA will emerge. The potential benefits of this approach must be balanced against the costs of monitoring, and further research is required.

The Association between Clinical Response to Ustekinumab and Immunogenicity to Ustekinumab and Prior Adalimumab

Background

Immunogenicity due to antidrug antibodies (ADA) to tumor necrosis factor (TNF)-α antagonists is known to decrease treatment response. However, few studies have investigated ADA in ustekinumab, an interleukin-12 and -23 antagonist, in a clinical setting. This study aimed to investigate the immunogenicity of ustekinumab and its clinical consequences in psoriasis.

Methods

This prospective observational study enrolled 76 patients with plaque psoriasis who were treated with ustekinumab for a minimum of 7 months. Blood samples were drawn just prior to scheduled ustekinumab injection during clinic visits. Levels of anti-ustekinumab antibody (AUA) and serum ustekinumab concentration were measured respectively by radioimmunoassays and enzyme-linked immunoassays respectively, and correlated to clinical data and Psoriasis Area and Severity Index (PASI).

Results

AUA was detected in 6.5% of patients after a mean of 13 months of treatment. Patients with positive AUA had significantly lower serum ustekinumab concentrations (0.01 vs. 0.2 mg/L, p<0.001) and lower PASI 50 response than patients without AUA (0% vs. 69%, p = 0.004).The percentage of AUA formation was comparable between patients who had failed previous adalimumab with or without anti-adalimumab antibodies (AAA) (14.3% vs. 12.5%, p = 1.00). However, a higher proportion of switchers without AAA obtaining PASI50 (71.4% vs. 37.5%) and PASI75 response (42.9% vs.12.5%) within 7 months of ustekinumab treatment than with AAA though this difference did not reach statistical significance.

Conclusions

Our results suggest that presence of AUA was significantly associated with treatment failure for ustekinumab, though limited by a small sample size. Also, determining the presence of ADA to antecedent TNF-α antagonists may assist in choosing an optimized subsequent treatment modality achieving treatment success.

HLA-B27-Homodimer-Specific Antibody Modulates the Expansion of Pro-Inflammatory T-Cells in HLA-B27 Transgenic Rats

Objectives

HLA-B27 is a common genetic risk factor for the development of Spondyloarthritides (SpA). HLA-B27 can misfold to form cell-surface heavy chain homodimers (B27₂) and induce pro-inflammatory responses that may lead to SpA pathogenesis. The presence of B27₂ can be detected on leukocytes of HLA-B27+ Ankylosing spondylitis (AS) patients and HLA-B27 transgenic rats. We characterized a novel B27₂–specific monoclonal antibody to study its therapeutic use in HLA-B27 associated disorders.

Methods

The monoclonal HD5 antibody was selected from a phage library to target cell-surface B27₂ homodimers and characterized for affinity, specificity and ligand binding. The immune modulating effect of HD5 was tested in HLA-B27 transgenic rats. Onset and progression of disease profiles were monitored during therapy. Cell-surface B27₂ and expansion of pro-inflammatory cells from blood, spleen and draining lymph nodes were assessed by flow cytometry.

Results

HD5 bound B27₂ with high specificity and affinity (K^d = 0.32 nM). HD5 blocked cell-surface interaction of B27₂ with immune regulatory receptors KIR3DL2, LILRB2 and Pirb. In addition, HD5 modulated the production of TNF from CD4+ T-cells by limiting B27₂ interactions in vitro. In an HLA-B27 transgenic rat model repetitive dosing of HD5 reduced the expansion of pro-inflammatory CD4+ T-cells, and decreased the levels of soluble TNF and number of cell-surface B27₂ molecules.

Conclusion

HD5 predominantly inhibits early TNF production and expansion of pro-inflammatory CD4+ T-cells in HLA-B27 transgenic rats. Monoclonal antibodies targeting cell-surface B27₂ propose a new concept for the modulation of inflammatory responses in HLA-B27 related disorders.

The effect of comedication with conventional synthetic disease modifying antirheumatic drugs on TNF inhibitor drug survival in patients with ankylosing spondylitis and undifferentiated spondyloarthritis: results from a nationwide prospective study

Objective

To assess the effect of comedication with conventional synthetic disease modifying antirheumatic drugs (csDMARDs) on retention to tumour necrosis factor inhibitor (TNFi) therapy in patients with ankylosing spondylitis (AS) and undifferentiated spondyloarthritis (uSpA).

Methods

Data on patients with a clinical diagnosis of AS or uSpA starting treatment with adalimumab, etanercept or infliximab as their first TNFi during 2003–2010 were retrieved from the Swedish national biologics register and linked to national population based registers. Five-year drug survival was analysed by Cox regression with age, sex, baseline csDMARD comedication, TNFi type, prescription year and covariates representing frailty and socioeconomic status. AS and uSpA were analysed separately. Sensitivity analyses included models with csDMARD as a time-dependent covariate and adjustments for additional potential confounders.

Results

1365 patients with AS and 1155 patients with uSpA were included, of whom 40.8% versus 50.3% used csDMARD comedication at baseline. In the unadjusted analyses superior drug survival was observed for patients using versus not using csDMARD comedication among patients with AS (p<0.001) but not among patients with uSpA (p=0.175). In the multivariable Cox regression analyses comedication with csDMARD was associated with better retention to TNFi therapy both in AS (HR 0.71, p<0.001) and uSpA (HR 0.82, p=0.020). The results were similar with csDMARD comedication as a time-dependent covariate, and the associations were retained when adjusting for erythrocyte sedimentation rate, C-reactive protein, patient global, swollen joints, uveitis, psoriasis and inflammatory bowel disease.

Conclusions

In this large register study of patients with AS and uSpA, use of csDMARD comedication was associated with better 5-year retention to the first TNFi.

Pharmacologic treatment of psoriatic arthritis and axial spondyloarthritis with traditional biologic and non-biologic DMARDs

This manuscript focuses on the pharmacologic treatment of psoriatic arthritis and axial spondyloarthritis - including ankylosing spondylitis - using traditional biologic and non-biologic disease-modifying antirheumatic drugs. Early treatment of psoriatic arthritis and axial spondyloarthritis/ankylosing spondylitis as well as the treat-to-target concept receive particular attention. This review also surveys recent national and international guidelines for the treatment of both psoriatic arthritis and couches practice recommendations for axial spondyloarthritis/ankylosing spondylitis within the context of various international guidelines.

Functional analysis of the anti-adalimumab response using patient-derived monoclonal antibodies

The production of antibodies to adalimumab in autoimmune patients treated with adalimumab is shown to diminish treatment efficacy. We previously showed that these antibodies are almost exclusively neutralizing, indicating a restricted response. Here, we investigated the characteristics of a panel of patient-derived monoclonal antibodies for binding to adalimumab. Single B-cells were isolated from two patients, cultured, and screened for adalimumab specificity. Analysis of variable region sequences of 16 clones suggests that the immune response against adalimumab is broad, involving multiple B-cell clones each using different combinations of V(D)J segments. A strong bias for replacement mutations in the complementarity determining regions was found, indicating an antigen-driven response. We recombinantly expressed 11 different monoclonal antibodies and investigated their affinity and specificity. All clones except one are of high affinity (Kd between 0.6 and 233 pm) and compete with TNF as well as each other for binding to adalimumab. However, binding to a panel of single-point mutants of adalimumab indicates markedly different fine specificities that also result in a differential tendency of each clone to form dimeric and multimeric immune complexes. We conclude that although all anti-adalimumab antibodies compete for binding to TNF, the response is clonally diverse and involves multiple epitopes on adalimumab. These results are important for understanding the relationship between self and non-self or idiotypic determinants on therapeutic antibodies and their potential immunogenicity.

Adalimumab serum levels and antidrug antibodies towards adalimumab in peripheral spondyloarthritis: no association with clinical response to treatment or with disease relapse upon treatment discontinuation

Introduction

In this study, we evaluated the clinical relevance of serum drug levels and antidrug antibodies (ADAbs) with regard to response to treatment, as well as to relapse upon treatment discontinuation, in peripheral spondyloarthritis (pSpA) patients treated with adalimumab.

Methods

The study included 26 pSpA patients treated with adalimumab for either 12 weeks (n = 12) or 24 weeks (n = 14) in a randomized controlled trial. Patients achieving inactive disease measured by Ankylosing Spondylitis Disease Activity Score (ASDAS) at the end of the treatment period were classified as responders. Clinical characteristics, serum trough adalimumab levels and ADAbs were assessed at the end of the treatment period and at follow-up (upon relapse or, in absence of relapse, at 16 weeks after discontinuation).

Results

Serum adalimumab levels measured 2 weeks after the last adalimumab administration ranged from <0.002 to 23.0 μg/ml, with a median of 11.5 μg/ml. These levels were associated with neither response to treatment or disease activity measurements at the end of treatment nor with the occurrence of relapse and time to relapse after discontinuation of treatment. Antiadalimumab ADAbs were present in 23% of the patients at end of treatment and in 35% at follow-up after treatment discontinuation, indicating that ADAbs were masked by the presence of the drug in some patients. However, ADAbs at the end of treatment and at follow-up were not different between responders and nonresponders and were not associated with relapse upon discontinuation of treatment.

Conclusions

There is no clear association between adalimumab serum levels or antiadalimumab ADAbs with clinical response to treatment or with relapse upon treatment discontinuation in pSpA.

Trial registration

Netherlands Trial Register ID: NTR1806 (registered 7 May 2009)

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

BACKGROUND

Previous data have shown that etanercept levels are associated with clinical response in rheumatoid arthritis. However, for ankylosing spondylitis (AS), data regarding this topic are inconclusive.

OBJECTIVES

To investigate the relationship between etanercept levels and clinical response in patients with AS.

METHODS

Observational prospective cohort study of 162 patients with AS =treated with etanercept, monitored during 24 weeks of treatment. Etanercept trough levels were determined, retrospectively, using an ELISA. Disease activity was measured using AS Disease Activity Score (ASDAS), including C-reactive protein (CRP) and Bath AS Disease Activity index (BASDAI). Active disease was defined as ASDAS≥2.1. Since etanercept is a drug administered at home there might have been some variation in trough level sampling.

RESULTS

At 24 weeks etanercept levels were significantly higher in patients with ASDAS<2.1, (3.8 mg/L; IQR 2.5-5.2) compared with patients with ASDAS≥2.1 (2.3 mg/L; IQR 1.2-3.4; p≤0.001). Generalised estimating equation analysis demonstrated a statistically significant association between etanercept levels and ASDAS, BASDAI, CRP and erythrocyte sedimentation rate (all p<0.001). When patients were categorised into quartiles according to etanercept levels, the lowest quartile (etanercept<1.80 mg/L) comprised 35% of all patients with ASDAS≥2.1 while the highest quartile comprised only 14%.

CONCLUSIONS

Disease activity and inflammation are associated with etanercept levels in patients with AS at 24 weeks of treatment. Measuring etanercept levels might help in identifying overtreatment and undertreatment and optimise etanercept therapy in AS.

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.

Recombinant murine growth hormone particles are more immunogenic with intravenous than subcutaneous administration

Evaluation and mitigation of the risk of immunogenicity to protein aggregates and particles in therapeutic protein products remains a primary concern for drug developers and regulatory agencies. To investigate how the presence of protein particles and the route of administration influence the immunogenicity of a model therapeutic protein, we measured the immune response in mice to injections of formulations of recombinant murine growth hormone (rmGH) that contained controlled levels of protein particles. Mice were injected twice over 6 weeks with rmGH formulations via the subcutaneous, intraperitoneal, or intravenous (i.v.) routes. In addition to soluble, monomeric rmGH, the samples prepared contained either nanoparticles of rmGH or both nano- and microparticles of rmGH.The appearance of anti-rmGH IgG1, IgG2a, IgG2b, IgG2c, and IgG3 titers following the second injection of both preparations implies that multiple mechanisms contributed to the immune response. No dependence of the immune response on particle size and distribution was observed. The immune response measured after the second injection was most pronounced when i.v. administration was used. Despite producing high anti-rmGH titers mice appeared to retain the ability to properly regulate and use endogenous growth hormone.

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.

The immunogenicity to the first anti-TNF therapy determines the outcome of switching to a second anti-TNF therapy in spondyloarthritis patients

Introduction

Anti-TNF drugs have proven to be effective against spondyloarthritis (SpA), although 30% of patients fail to respond or experience adverse events leading to treatment discontinuation. In rheumatoid arthritis, the presence of anti-drug antibodies (ADA) against the first TNF inhibitor influences the outcome after switching. Our aim was to assess whether the response to a second anti-TNF drug is related to the previous development of ADA to the first anti-TNF drug SpA patients.

Methods

Forty-two SpA patients began a second anti-TNF drug after failing to respond to the first anti-TNF therapy. Clinical activity was assessed by the Ankylosing Spondylitis Disease Activity Score (ASDAS) at baseline (at the beginning of the first and second anti-TNF therapy) and at 6 months after switching. The drug and ADA levels were measured by ELISA before each administration.

Results

All patients were treated with anti-TNF drugs and mainly due to inefficacy were switched to a second anti-TNF drug. Eleven of 42 (26.2%) developed ADA during the first biologic treatment. At baseline, no differences in ASDAS were found in patients with or without ADA to the first anti-TNF drug (3.52 ± 1.03 without ADA vs. 3.14 ± 0.95 with ADA, p = 0.399) and to the second anti-TNF drug (3.36 ± 0.94 without ADA vs. 3.09 ± 0.91 with ADA, p = 0.466). At 6 months after switching, patients with previous ADA had lower disease activity (1.62 ± 0.93 with ADA vs. 2.79 ± 1.01 without ADA, p = 0.002) and most patients without ADA had high disease activity state by the ASDAS (25 out of 31 (80.6%) without ADA vs. 3 out of 11 (27.3%) with ADA, p = 0.002).

Conclusions

In SpA the failure to respond to the first anti-TNF drug due to the presence of ADA predicts a better clinical response to a second anti-TNF drug.

Biologic therapies for spondyloarthritis: what is new?

The course of axial spondyloarthritis (axSpA), including ankylosing spondylitis (AS), is strongly influenced by the degree of disease activity over time, which is mainly based on inflammation, and by the impairment of function, which is based on structural damage-mainly, new bone formation-and inflammation. In AS, nonsteroidal anti-inflammatory agents are currently recommended as the first choice of medical therapy, and there is also a clear role for regular exercise and physiotherapy in order to preserve and prevent loss of spinal mobility. For patients who have insufficiently responded to conventional medications, there are now four biologics approved for the treatment of patients with active AS in many countries, all directed against TNFα: infliximab, etanercept, adalimumab, and golimumab; studies with certolizumab are currently ongoing. Several studies with patients classified as nonradiographic axSpA have also shown a good response to TNF blockers; in patients with early disease and high CRP levels, the response rates were even better. Long-term studies with TNF blockers have shown declining retention rates over time but sustained clinical efficacy in the patients who remained on treatment. States of drug-free remission are rarely reached and only for relatively short periods of time. More studies including magnetic resonance imaging (MRI) are needed to further examine the lack of effect of anti-TNF treatment on radiographic progression in the axial skeleton. Whether the effect of an early intervention with biologics will prevent the development of bone growth in patients with nonradiographic axial SpA remains to be seen. Biologics other than TNF blockers are currently not recommended for the treatment of patients with axSpA, because of insufficient evidence of clinically relevant efficacy. The anti-IL-17a antibody secukinumab may be efficacious, on the basis of a proof-of-concept trial. Finally, first data on biosimilars of TNF blockers have recently been presented.