Relationship between the clinical response to adalimumab treatment and serum levels of adalimumab and anti-adalimumab antibodies in patients with psoriatic arthritis

Adalimumab Dose Reduction and Withdrawal in Stable Non-Infectious Pediatric Uveitis: An Open-Label, Prospective, Pilot Study

PURPOSES

This study investigated the feasibility of adalimumab (ADA) dose reduction and withdrawal strategy in children with stable pediatric non-infectious uveitis (PNIU).

METHODS

This open-label prospective pilot trial recruited 18 stable PNIU patients (33 eyes) between two and eighteen years old who were treated with standard doses of ADA (20/40 mg every 2 weeks) plus oral methotrexate. The interval of ADA injection was extended to 4 weeks and followed up for 24 weeks. If the uveitis remained stable, ADA was discontinued and followed up for another 24 weeks. ADA was considered successfully stopped if no relapse occurred during this period. The relapse-free survival rate, best corrected visual acuity (BVCA), anterior chamber cell (ACC), vitritis, macular thickness (MT), and serum ADA levels were evaluated. Approval Number: 2021KYPJ201. ClinicalTrials.gov identifier: NCT05155592.

RESULTS

The relapse-free survival rate was 22.2% (4/18) at 48 weeks. 33.3% (6/18) of patients relapsed when ADA was given every 4 weeks, while 44.5% of patients (8/18) relapsed after ADA was stopped. The four patients successfully withdrawn from ADA were all diagnosed with BD. No statistically significant differences (p > 0.05) were observed in BCVA and MT between baseline and final follow-up. The proportion of ACC and vitritis exhibited an upward trend (p < 0.05) during follow-up. Serum ADA gradually decreased to zero during follow-up in both non-recurrence and recurrence groups.

CONCLUSIONS

In PNIU children who reached remission for 6 months, ADA dose reduction and withdrawal were associated with a high risk of inflammation recurrence. Timely adjustment of ADA to the last effective dosage frequency can regain control of the inflammation. Detection of ADA serum levels in patients with recurrence may help find the appropriate interval of ADA use.

The role of antidrug antibodies in ustekinumab therapy and the impact of methotrexate

OBJECTIVE

We investigated the impact of concomitant MTX on ustekinumab (UST) levels and antidrug antibody (ADA) formation in PsA and evaluated consequences in pharmacodynamics and pharmacokinetics.

METHODS

We conducted a post-hoc analysis on 112 PsA serum samples of subjects treated with open-label UST and either concomitant MTX (UST/MTX, n = 58) or placebo (UST/pbo, n = 54) obtained in a randomized (1:1), double-blind, multicentre trial. A validated antibody-binding-based multitiered testing was used to detect ADA and ADA with neutralizing capacity (nADA). The impact of MTX on UST immunogenicity was analysed by comparison of UST/pbo with UST/MTX cohorts at different time points. Patient- and disease-related predispositions for ADA formation were investigated with multiple linear regression analysis. Immunogenicity impact on pharmacokinetics, safety and efficacy was determined by cohort comparison between patients with and without ADA formation.

RESULTS

Over 52 weeks, 11 UST/pbo- and 19 UST/MTX-treated patients developed ADA (P > 0.05). In the UST/pbo cohort, the visit-dependent UST levels were in the range of 0.047 (0.05) -0.110 (0.07) µg/ml overall, and 0.037 (0.04)-0.091 (0.08) µg/ml in ADA-confirmed subjects. In UST/MTX-treated patients, the UST levels exhibited an intervisit variation in the range of 0.0502 (0.04)-0.106 (0.07) µg/ml overall and 0.029 (0.03)-0.097 (0.07) µg/ml in ADA positive subjects (P > 0.05). At week 52, ADA-confirmed patients did not differ significantly (P > 0.05) in safety or clinical outcomes from ADA-negative patients.

CONCLUSION

Concomitant MTX had no significant impact on UST immunogenicity. Furthermore, ADA formation was not associated with impairments in UST safety, efficacy or trough levels.

TRIAL REGISTRATION

ClinicalTrials.gov, https://clinicaltrials.gov, NCT03148860.

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

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

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.

Cost-Effectiveness of Therapeutic Drug Monitoring-Guided Adalimumab Therapy in Rheumatic Diseases: A Prospective, Pragmatic Trial

Introduction

To assess the clinical and cost-effectiveness of therapeutic drug monitoring (TDM) based on serum adalimumab levels compared to standard of care in patients with rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis.

Methods

This was a non-inferiority, multicentric, non-randomized, pragmatic trial including adult patients diagnosed with moderate-to-severe, clinically stable rheumatic diseases treated with adalimumab. Consecutive patients were assigned 1:2 to the control (CG) or the intervention group (IG), based on the site of inclusion, and followed up for 18 months. Adalimumab serum levels were measured at each study visit and released to the IG only to modify dosing strategy. Data on disease activity, healthcare resource utilization and health-related quality of life (HRQoL) measured through the EQ-5D-5L were collected. Number of persistent and overall flares, time to first flare, days experiencing high disease activity, total direct costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio (ICER) were calculated.

Results

Of the 169 recruited patients, 150 were included in the analysis (52 and 98 patients in the CG and IG, respectively). The primary endpoint was not met as persistent flares were not significantly lower in the IG, although mean (SD) number of flares was numerically lower in the IG (0.67 [0.70] versus 0.90 [0.82], P = 0.073), respectively. Based on EQ-5D-5L utilities, HRQoL was significantly higher in the IG at 3 (P = 0.001) and 6 months (P = 0.035), which overall translated into 0.075 QALYs gained per patient for the IG at month 18. Overall, direct costs were significantly lower for the IG patients (€15,311.59 [4,870.04] versus €17,378.46 [6,556.51], P = 0.030), resulting in the intervention being dominant, leading to increased QALY at a lower overall cost

Conclusion

Adalimumab dose tapering based on TDM for rheumatic patients led to an increased quality of life and QALY gain and entailed lower costs, being a more cost-effective alternative than clinically guided management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-021-00345-5.

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

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

Guselkumab in patients with active psoriatic arthritis who were biologic-naive or had previously received TNFα inhibitor treatment (DISCOVER-1): a double-blind, randomised, placebo-controlled phase 3 trial

BACKGROUND

Many patients with psoriatic arthritis have an inadequate response to tumor necrosis factor (TNF) inhibitors. Guselkumab, a specific inhibitor of interleukin-23 (IL-23) via IL-23 p19 subunit binding, significantly improved psoriatic arthritis signs and symptoms with an acceptable safety profile in a phase 2 trial.

METHODS

This multicentre, double-blind, randomised, placebo-controlled, phase 3 trial was done at 86 sites in 13 countries across Asia, Australasia, Europe, and North America and enrolled adults with active psoriatic arthritis (at least three swollen and three tender joints; and C-reactive protein ≥0·3 mg/dL) despite standard therapies. Eligibility criteria included inadequate response to or intolerance of standard treatment, including at least 4 months of apremilast, at least 3 months of non-biologic disease-modifying antirheumatic drugs (DMARDs), or at least 4 weeks of non-steroidal anti-inflammatory drugs for psoriatic arthritis. About 30% of study participants could have previously received one or two TNF inhibitors. Patients were randomly assigned (1:1:1, computer-generated permuted blocks; stratified by baseline DMARD and previous TNF inhibitor use) to subcutaneous guselkumab 100 mg every 4 weeks; guselkumab 100 mg at weeks 0, 4, then every 8 weeks; or matching placebo. The primary endpoint was American College of Rheumatology 20% improvement (ACR20) at week 24 in all patients per assigned treatment group using non-responder imputation. Safety was assessed in all patients per treatment received. This trial is registered at ClinicalTrials.gov, NCT03162796 (active, not recruiting).

FINDINGS

From Aug 28, 2017, to Aug 17, 2018, we screened 624 patients, of whom 381 were randomly assigned and treated with guselkumab every 4 weeks (n=128), guselkumab every 8 weeks (n=127), or placebo (n=126). 362 patients continued study treatment up to week 24. The primary endpoint was met: ACR20 at week 24 was achieved by significantly greater proportions of patients in the guselkumab every 4 weeks group (76 [59%] of 128 [95% CI 50-68]) and every 8 weeks group (66 [52%] of 127 [43-61]) than in the placebo group (28 [22%] of 126 [15-30]), with percentage differences versus placebo of 37% (95% CI 26-48) for the every 4 weeks group and 30% (19-41) for the every 8 weeks group (both p<0·0001). Serious adverse events up to week 24 occurred in no patients receiving guselkumab every 4 weeks, four (3%) patients receiving guselkumab every 8 weeks, and five (4%) patients receiving placebo. Up to week 24, one patient in the placebo group died from cardiac failure and two had serious infections; no guselkumab-treated patient died or had serious infections.

INTERPRETATION

Guselkumab demonstrated a favourable benefit-risk profile and might be an effective treatment option for patients with active psoriatic arthritis.

FUNDING

Janssen Research and Development.

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.

In Vitro ELISA and Cell-Based Assays Confirm the Low Immunogenicity of VNAR Therapeutic Constructs in a Mouse Model of Human RA: An Encouraging Milestone to Further Clinical Drug Development

Anti-drug antibodies (ADAs), specific for biotherapeutic drugs, are associated with reduced serum drug levels and compromised therapeutic response. The impact of ADA on the bioavailability and clinical efficacy of blockbuster anti-hTNF-α monoclonal antibodies is well recognised, especially for adalimumab and infliximab treatments, with the large and complex molecular architecture of classical immunoglobulin antibody drugs, in part, responsible for the immunogenicity seen in patients. The initial aim of this study was to develop solid-phase enzyme-linked immunosorbent assays (ELISA) and an in vitro cell-based method to accurately detect ADA and estimate its impact on the preclinical in vivo efficacy outcomes of two novel, nonimmunoglobulin VNAR fusion anti-hTNF-α biologics (Quad-X™ and D1-NDure™-C4) and Humira®, a brand of adalimumab. Serum drug levels and the presence of ADA were determined in a transgenic mouse model of polyarthritis (Tg197) when Quad-X™ and Humira® were dosed at 1 mg/kg and D1-NDure™-C4 was dosed at 30 mg/kg. The serum levels of the Quad-X™ and D1-NDure™-C4 modalities were consistently high and comparable across all mice within the same treatment groups. In 1 mg/kg and 3 mg/kg Quad-X™- and 30 mg/kg D1-NDure™-C4-treated mice, an average trough drug serum concentration of 8 μg/mL, 50 μg/mL, and 350 μg/mL, respectively, were estimated. In stark contrast, Humira® trough serum concentrations in the 1 mg/kg treatment group ranged from <0.008 μg/mL to 4 μg/mL with trace levels detected in 7 of the 8 animals treated. Trough serum Humira® and Quad-X™ concentrations in 3 mg/kg treatment samples were comparable; however, the functionality of the detected Humira® serum was significantly compromised due to neutralising ADA. The impact of ADA went beyond the simple and rapid clearance of Humira®, as 7/8 serum samples also showed no detectable capacity to neutralise hTNF-α-mediated cytotoxicity in a murine fibrosarcoma (L929) cell assay. The neutralisation capacity of all the VNAR constructs remained unchanged at the end of the experimental period (10 weeks). The data presented in this manuscript goes some way to explain the exciting outcomes of the previously published preclinical in vivo efficacy data, which showed complete control of disease at Quad-X™ concentrations of 0.5 mg/kg, equivalent to 10x the in vivo potency of Humira®. This independent corroboration also validates the robustness and reliability of the assay techniques reported in this current manuscript, and while it comes with the caveat of a mouse study, it does appear to suggest that these particular VNAR constructs, at least, are of low inherent immunogenicity.

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.

Systematic review: efficacy and safety of switching patients between reference and biosimilar infliximab

BACKGROUND

Biosimilar versions of widely prescribed drugs, including the tumour-necrosis factor antagonist infliximab, are becoming increasingly available. As biosimilars are not identical copies of reference products, evidence may be required to demonstrate that switching between a reference biologic and biosimilars is safe and efficacious. To establish interchangeability, US Food and Drug Administration guidance states that studies must demonstrate that biosimilars remain equivalent or non-inferior to a reference product after multiple switches between products.

AIMS

To investigate the evidence evaluating the safety and efficacy of switching between reference and biosimilar infliximab in patients with inflammatory disorders, including Crohn's disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and plaque psoriasis.

METHODS

Published studies presenting data on switching between reference and biosimilar infliximab were identified by searching the MEDLINE database. Congress abstracts were identified by searching the EMBASE database and manually searching abstracts from relevant congresses.

RESULTS

A total of 113 journal articles and 149 abstracts were found. Of these, 70 were considered relevant and included in this analysis. Most of the publications were uncontrolled, observational studies. Data from six randomised, controlled trials were identified. In general, the evidence revealed no clinically important efficacy or safety signals associated with switching.

CONCLUSIONS

While available data have not identified significant risks associated with a single switch between reference and biosimilar infliximab, the studies available currently report on only single switches and were mostly observational studies lacking control arms. Additional data are needed to explore potential switching risks in various populations and scenarios.

Pharmacokinetic equivalence, comparable safety, and immunogenicity of an adalimumab biosimilar product (M923) to Humira in healthy subjects

The aims of this randomized, double-blind, three-arm, single-dose study were to demonstrate pharmacokinetic (PK) equivalence of the adalimumab biosimilar M923 (hereafter referred to as "M923") to each of 2 reference products, and to assess M923's safety and immunogenicity. Primary PK endpoints were maximum observed concentration (C_max ), area under the curve (AUC) from time 0 extrapolated to infinity (AUC_0-inf ), and AUC from time 0 to 336 hours (AUC_0-336 ). Secondary endpoints included safety and immunogenicity assessments. Healthy subjects were randomized 1:1:1 to receive a 40-mg dose of M923 (n = 107); adalimumab US Humira (n = 105), hereafter referred to as "US Humira"; or adalimumab EU Humira (n = 103), hereafter referred to as "EU Humira." PK equivalence was demonstrated for all primary PK endpoints. Geometric least squares means ratios (GMRs) for C_max , AUC_0-inf , and AUC_0-336 were 99.4, 100.9, and 100.5, respectively, between the M923 and EU Humira arms and 102.6, 104.2, and 102.9 between the M923 and US Humira arms. The 90% confidence intervals of the GMRs for all PK endpoints were within prespecified confidence bounds of 80%-125%. Adverse event rates were similar across the M923 (47.7%), US Humira (50.9%), and EU Humira (53.3%) arms and were generally mild (73.7%) or moderate (22.0%). The proportion of subjects with a confirmed antidrug antibody (ADA) response was similar across study arms. This study demonstrated bioequivalent PK among M923, US Humira, and EU Humira and demonstrated that the PK parameters were consistent with similar safety and tolerability profile and ADA response rates.

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 Versus Adalimumab for Psoriatic Arthritis: Comparative Effectiveness up to 48 Weeks Using a Matching-Adjusted Indirect Comparison

INTRODUCTION

Secukinumab and adalimumab are approved for adults with active psoriatic arthritis (PsA). In the absence of direct randomized controlled trial (RCT) data, matching-adjusted indirect comparison can estimate the comparative effectiveness in anti-tumor necrosis factor (TNF)-naïve populations.

METHODS

Individual patient data from the FUTURE 2 RCT (secukinumab vs. placebo; N = 299) were adjusted to match baseline characteristics of the ADEPT RCT (adalimumab vs. placebo; N = 313). Logistic regression determined adjustment weights for age, body weight, sex, race, methotrexate use, psoriasis affecting ≥ 3% of body surface area, Psoriasis Area and Severity Index score, Health Assessment Questionnaire Disability Index score, presence of dactylitis and enthesitis, and previous anti-TNF therapy. Recalculated secukinumab outcomes were compared with adalimumab outcomes at weeks 12 (placebo-adjusted), 16, 24, and 48 (nonplacebo-adjusted).

RESULTS

After matching, the effective sample size for FUTURE 2 was 101. Week 12 American College of Rheumatology (ACR) response rates were not significantly different between secukinumab and adalimumab. Week 16 ACR 20 and 50 response rates were higher for secukinumab 150 mg than for adalimumab (P = 0.017, P = 0.033), as was ACR 50 for secukinumab 300 mg (P = 0.030). Week 24 ACR 20 and 50 were higher for secukinumab 150 mg than for adalimumab (P = 0.001, P = 0.019), as was ACR 20 for secukinumab 300 mg (P = 0.048). Week 48 ACR 20 was higher for secukinumab 150 and 300 mg than for adalimumab (P = 0.002, P = 0.027), as was ACR 50 for secukinumab 300 mg (P = 0.032).

CONCLUSIONS

In our analysis, patients with PsA receiving secukinumab were more likely to achieve higher ACR responses through 1 year (weeks 16-48) than those treated with adalimumab. Although informative, these observations rely on a subgroup of patients from FUTURE 2 and thus should be considered interim until the ongoing head-to-head RCT EXCEED can validate these findings.

FUNDING

Novartis Pharma AG.

The comparative immunogenicity of biologic therapy and its clinical relevance in psoriatic arthritis: a systematic review of the literature

INTRODUCTION

Biologic agents have demonstrated efficacy in treating patients with psoriatic arthritis (PsA). Biologic agents also have an intrinsic capacity to induce an immune response in patients that could result in unwanted adverse events and/or treatment failure.

AREAS COVERED

In this systematic literature review, the authors document the incidence of immune responses, primarily anti-drug antibodies (ADA), to the biologic therapeutic agents currently in clinical practice for the treatment of PsA. The authors discuss the importance of these responses with respect to clinical practice.

EXPERT OPINION

Our evaluation of the published literature shows that the immune responses to the various biologic therapeutic agents currently being used to treat PsA are similar to those observed for these agents in other rheumatic diseases. Moreover, similar to observations in other rheumatic diseases, the incidence of ADA formation to biologic agents in patients with PsA is often decreased when patients are given concomitant treatment with disease-modifying anti-rheumatic drugs. These data strongly suggest that the immune response is a characteristic of the biologic agent. Using therapeutic drug monitoring may be an approach to assess the immune response to the agent and to mitigate the potential impact on efficacy and safety, and consequently optimize treatment.

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.

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.

Tumor necrosis factor inhibitors in psoriatic arthritis

INTRODUCTION

Psoriatic arthritis (PsA) is a chronic inflammatory disease that can result in significant disability. With the emergence of tumor necrosis factor inhibitors (TNFi), therapeutic outcomes in PsA have improved substantially. The clinical efficacy and the inhibition of radiographic progression demonstrated by TNFi have transformed the management of PsA. However, there is still an unmet need for a subset of patients who do not respond adequately to TNFi. Areas covered: This review provides an overview of the pharmacokinetics of TNFi, the efficacy of TNFi in PsA, and the role of immunogenicity of TNFi in the treatment of PsA. In addition, we address the use of TNFi in the setting of other medications utilized in the treatment of PsA and the potential future role of biosimilars. Expert commentary: Monoclonal antibodies exhibit complex and widely variable pharmacokinetics. The study of factors that can affect the pharmacokinetics, such as immunogenicity, is valuable to further define and understand the use of TNFi in PsA, especially in the subset of patients who do not respond adequately to these agents or lose effectiveness over time.

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.

Presence of antidrug antibodies correlates inversely with the plasma tumor necrosis factor (TNF)-α level and the efficacy of TNF-inhibitor therapy in psoriasis

Antidrug antibodies have been shown to be associated with a loss of response during biologic therapy. Despite the potential association, there has been no report on the simultaneous monitoring of the following parameters in psoriasis: presence of neutralizing antibodies, plasma tumor necrosis factor (TNF)-α concentration, TNFi concentration and disease activity. Plasma concentrations of adalimumab, infliximab, etanercept and their respective antidrug antibodies, as well as plasma concentrations of TNF-α were measured in 77 psoriasis patients receiving biologic therapy, and the values were correlated with the clinical activity of the skin disease. Antidrug antibodies were identified in the plasma of 25% of infliximab-treated patients and 29.6% of adalimumab-treated patients, but not in the etanercept group. Clinical severity scores were significantly higher in the antibody-positive patients. In patients receiving infliximab or adalimumab therapy, the presence of antidrug antibodies was directly associated with reduced plasma TNF-inhibitor concentration and elevated plasma TNF-α level.

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.

Comparative effectiveness of biologic monotherapy versus combination therapy for patients with psoriatic arthritis: results from the Corrona registry

Objectives

To characterise the comparative effectiveness of combination therapy (a tumour necrosis factor inhibitor (TNFi) and a conventional synthetic disease-modifying antirheumatic drug (csDMARD) such as methotrexate) and monotherapy (TNFi only) for psoriatic arthritis (PsA) from a large US registry.

Methods

The analysis included adult patients with PsA who were enrolled in the Corrona database (ClinicalTrials.gov, NCT01402661), had initiated a TNFi, were biologic naïve, and had a follow-up visit ≥90 days after drug initiation. The endpoints of the analysis were TNFi persistence (drug survival) and time to Clinical Disease Activity Index (CDAI) remission. All analyses were performed using propensity scoring, which were estimated using CDAI and patient sex, to control for channelling bias.

Results

Of 519 patients meeting the inclusion criteria (318 with combination therapy and 201 with monotherapy), the analysis population was 497 for TNFi persistence and 380 for time to remission. The difference between combination therapy (TNFi+methotrexate, 91% of patients; TNFi+other csDMARD, 9%) and monotherapy was not statistically significant for TNFi persistence (32 and 31 months, p=0.73) and time to remission (21 and 25 months, p=0.56). Predictors of TNFi persistence included Hispanic ethnicity (longer persistence), PsA duration (longer persistence), history of methotrexate use (shorter persistence), body mass index (shorter persistence) and disease activity (shorter persistence).

Conclusions

Patients with PsA from a large US registry experienced similar TNFi persistence on combination therapy and monotherapy. Prospective, randomised clinical trials evaluating the efficacy of combination therapy versus monotherapy would provide much-needed clarity on treatment options for patients with PsA.

Trial registration number

NCT01402661.

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.

Immunogenicity of infliximab and adalimumab: what is its role in hypersensitivity and modulation of therapeutic efficacy and safety?

INTRODUCTION

TNF-α inhibitors have demonstrated efficacy both as monotherapy and in combination with disease-modifying antirheumatic drugs (DMARDs) in the treatment of chronic inflammatory immune-mediated diseases such as rheumatoid arthritis, Crohn's disease, ankylosing spondylitis, psoriasis and/or psoriatic arthritis, and may be administered off-label to treat disseminated granuloma annulare systemic lupus erythematosus and systemic sclerosis. There are several TNF-α inhibitors available for clinical use including infliximab, adalimumab, golimumab, certolizumab pegol and etanercept.

AREAS COVERED

infliximab and adalimumab can induce the development of anti-infliximab (anti-IFX) and anti-adalimumab (anti-ADA) monoclonal antibodies (mAbs). In this review, we discuss the impact of anti-IFX and anti-ADA mAbs upon efficacy and safety of these biological agents.

EXPERT OPINION

IgG/IgE neutralizing antibodies against infliximab and adalimumab decrease the possibility of achieving a minimal disease activity state or clinical remission, decrease drug survival, increase the need for doctors to prescribe a higher drug dosage and, finally, favor the occurrence of adverse events. Concomitant administration of DMARDs such as methotrexate or leflunomide prevents the development of neutralizing Abs against infliximab and adalimumab.

Population pharmacokinetics of infliximab in patients with inflammatory bowel disease: potential implications for dosing in clinical practice

BACKGROUND

Infliximab (IFX) is effective in the treatment of inflammatory bowel diseases (IBD). Currently, IFX is administered at fixed doses and intervals; however, costs are high and optimisation is necessary. Several publications indicate that IFX should be dosed on trough levels ≥3.0 mg/L. For optimising IFX dosing, the use of a pharmacokinetic model is important. Population pharmacokinetics of IFX have been described earlier; however, these models were not used for dose optimising.

AIMS

To develop a pharmacokinetic model for IFX in IBD patients that can be used for dose-optimisation of IFX and to predict serum trough levels in this population.

METHODS

An observational retrospective study was performed in 42 IFX-treated IBD patients. Serum samples were drawn before infusion at T = 0, 2, 6, 14, 22 and 54 weeks and analysed for IFX and antibodies against IFX (ATI). Relevant covariates were recorded and a population pharmacokinetic model was developed.

RESULTS

Individual plots created using the final model showed good correspondence between observed and model predicted values. Serum levels were influenced by ATI, disease activity, sex and albumin. Our results show that in patients without ATI target trough levels ≥3.0 mg/L can be achieved by increasing dosing intervals from 8 to 12 weeks combined with a dose increase. This results in a reduction of 33% in concomitant costs.

CONCLUSIONS

In IBD patients without ATI, trough level dosing based on longer intervals can reduce IFX therapy-related visits to the hospital with one-third. Trough level based dose intensification should always be justified by disease activity parameters.

Psoriatic arthritis: latest treatments and their place in therapy

Psoriatic arthritis (PsA) is a heterogeneous chronic inflammatory disease that may affect peripheral and axial joints, entheses, skin and nails, and other organs. Treatment with nonsteroidal anti-inflammatory drugs, steroid and disease-modifying antirheumatic drugs had been the backbone of traditional management of PsA for many years. However, improvement in our understanding of immunopathogenesis of PsA has led to new immunomodulatory therapies. Introduction of novel agents has raised the bar for treatment and helped drive research into additional therapeutic options.

Antidrug antibodies against TNF-blocking agents: correlations between disease activity, hypersensitivity reactions, and different classes of immunoglobulins

Although anti-TNF drugs have changed the clinical course of rheumatoid arthritis (RA), survival rates and resistance-to-therapy data confirm that about 30% of RA patients fail to respond. The aim of this study was to evaluate the correlations between the development of antidrug antibodies, specific IgG₄ antibodies against TNF inhibitors, and resistance to therapy in RA patients. This retrospective study involved 129 patients with established RA naïve to biological agents (98 females and 32 males, mean age 56.7±12.3 years, disease duration 6.3±1.2 years, baseline Disease Activity Score [DAS]-28 3.2–5.6) who received treatment with anti-TNF agents after the failure of conventional disease-modifying antirheumatic drugs (32 received infliximab [IFX], 58 etanercept [ETN], and 39 adalimumab [ADA]). After 6 months of treatment, the patients were classified as being in remission (DAS28 <2.6), having low disease activity (LDA; DAS28 2.6–3.2), or not responding (NR: DAS28 >3.2). The patients were also tested for serum antidrug antibodies and IgG₄ antibodies against TNF inhibitors. After 24 weeks of treatment, 38% of the ETN-treated patients and 28% of those treated with ADA had injection-site reactions; the rate of systemic reactions in the IFX group was 25%. The differences among the three groups were not statistically significant (P=0.382; ETN versus ADA P=0.319). The percentages of patients with adverse events stratified by drug response were: LDA 8% and NR 18% in the ADA group; in remission 3%, LDA 22%, and NR 10% in the ETN group; and LDA 6% and NR 16% in the IFX group (P=0.051). The percentages of patients with antidrug antibodies were: ADA 33.3%, ETN 11.5%, and IFX 10.3% (P=0.025; ADA versus ETN P=0.015). The percentages of patients with IgG₄ antibodies were: ADA 6%, ETN 13%, and IFX 26% (P=0.017; ADA versus ETN P=0.437). Associations between antidrug antibodies, specific IgG₄ antibodies, and adverse reactions were not significant for any of the three drugs. IgG₄ levels were higher in the ADA group than in the other two groups, and higher in the patients with worse DAS28 (NR) and in those experiencing adverse events. These data suggest a possible association between IgG₄ levels and worse DAS28 (r²=5.8%, P=0.011). The presence of specific IgG₄ antibodies against TNF blockers in patients with RA might affect the drugs’ activity. Patients with injection-site reactions and IgG₄ against ETN may show a decreased response.

Tumor necrosis factor inhibitors: clinical utility in autoimmune diseases

Tumor necrosis factor (TNF) production is amplified in several autoimmune disorders. In the 1990s, it became a validated therapeutic target used for the treatment of conditions such as rheumatoid arthritis and inflammatory bowel disease. Biologic drugs targeting TNF include engineered monoclonal antibodies and fusion proteins. Currently, there are 5 Food and Drug Administration-approved TNF inhibitors (infliximab, etanercept, adalimumab, certolizumab, and golimumab), representing close to $20 billion in sales. Clinical trials remain open to test their efficacy and safety compared with one another, as well as to measure clinical outcomes in different conditions and patient populations. The industry is also eager to develop biotherapeutics that are similar but cheaper than the currently existing biologics or are safer with higher efficacy; these are the so-called "biosimilars." Clinical utility of TNF inhibitors and indications of mono- or combined therapy with immunomodulators are reviewed here. Pharmacokinetics of the TNF inhibitors is affected by routes of administration, clearance mechanisms of immunoglobulins, and immunogenicity. Finally, strategies for management of treatment efficacy and increasing evidence for monitoring of serum concentration of TNF inhibitors are discussed, assessing for the presence of the antidrug antibodies and the different analytical methods available for laboratory testing. As clinical applications of the TNF inhibitors expand, and other classes join the revolution in the treatment of chronic inflammatory disorders, therapeutic drug monitoring of biologics will become increasingly important, with the potential to dramatically improve patient care and management.

Expert recommendations on treating psoriasis in special circumstances

INTRODUCTION AND OBJECTIVES

A great amount of information on systemic and biologic therapies for moderate to severe psoriasis is now available. However, applying the evidence in numerous clinical scenarios has engendered debate; under these circumstances, the consensus of experts is useful.

MATERIAL AND METHODS

A scientific committee systematically reviewed the literature relevant to 5 clinical scenarios. An online Delphi survey of dermatologists with experience treating moderate to severe psoriasis was then carried out in order to shed light on questions that remained unresolved by the available evidence.

RESULTS

Twenty-three dermatologists responded to the survey and consensus was reached on 37 (56%) of the 66 statements proposed. These results led to consensus on various clinical situations even though firm evidence was lacking. Thus, intermittent therapeutic regimens and strategies for reducing the intensity of treatment are considered appropriate for optimizing biologic treatment and reducing costs. The measurement of drug and antidrug antibody levels should be included routinely when following patients on biologics to treat psoriasis. Concomitant psoriatic arthritis or a history of cardiovascular conditions will influence the choice of biologic; in these situations, an agent with anti-tumor necrosis factor properties will be preferred. Tailored management is important when the patient is pregnant or intends to conceive; drug half-life and disease severity are important factors to take into consideration in these scenarios.

CONCLUSIONS

A combination of systematic review of the literature and structured discussion of expert opinion facilitates decision-making in specific clinical scenarios.

Prevalence of TNF-α Blocker Immunogenicity in Psoriatic Arthritis

Objective.

The longterm use of tumor necrosis factor (TNF)-α blockers is limited by the formation of neutralizing antibodies. To the best of our knowledge, immunogenicity in psoriatic arthritis (PsA) has not been investigated in depth. Our objective was to evaluate the prevalence and significance of TNF-α blocker immunogenicity in PsA.

Methods.

Consecutive patients with PsA treated with either infliximab (IFX), adalimumab (ADA), or etanercept (ETN) > 3 months participated in our cross-sectional study. Their demographic and clinical characteristics, skin and joint disease activity, and records of use of methotrexate (MTX) and other medications were collected. Drug levels (ELISA) and antidrug antibodies (ADAb; Bridging ELISA) were evaluated before the next injection or infusion.

Results.

A total of 93 patients with PsA were recruited (48 receiving ADA, 24 IFX, and 21 ETN), with a mean age of 53 years (range 21–83 yrs), composed of 53% women. One-fourth of the patients were concomitantly treated with MTX. Altogether, 77% of the patients demonstrated therapeutic drug levels. High levels of ADAb were found in 29% of patients taking ADA, 21% taking IFX, and 0% taking ETN. ADAb significantly correlated with lower drug levels, higher 28-joint Disease Activity Scores, and higher global assessments. MTX use correlated significantly with a lower prevalence of ADAb.

Conclusion.

Significant levels of ADAb were present in up to 29% of patients with PsA treated with ADA or IFX. ADAb clearly correlated with low therapeutic drug levels and higher disease activity variables. The use of MTX significantly decreased ADAb prevalence, and its use should be strongly considered in combination with TNF-α blocker antibodies in patients with PsA.

Tumour necrosis factor inhibitor monotherapy vs combination with MTX in the treatment of PsA: a systematic review of the literature

OBJECTIVES

The aim of this study was to review the available evidence on TNF inhibitor monotherapy vs combination therapy with MTX in PsA.

METHODS

A literature search was conducted up to and including October 2013 for randomized controlled trials (RCTs) and observational studies comparing TNF inhibitor monotherapy vs combination therapy with MTX in patients with PsA. Key information was extracted from the abstracts and/or full text of the articles retrieved.

RESULTS

Eleven published articles and three conference abstracts were retrieved, reporting on six RCTs of four TNF inhibitors. Most RCTs found no differences in efficacy for peripheral arthritis between patients treated with or without MTX. However, the studies were not powered to answer this question. Some data suggest that concomitant MTX may reduce the progression of structural damage. No significant differences in other outcomes have been reported. Data on TNF inhibitor monotherapy vs MTX combination therapy were reported from six registries. Three registries reported that the use of concomitant MTX did not affect the efficacy of TNF inhibitor therapy. Data from three European Union registries suggest that TNF inhibitor (especially mAbs) drug survival is superior in patients taking concomitant MTX, while one Canadian registry reported no difference.

CONCLUSION

Available evidence on the efficacy and safety of TNF inhibitor monotherapy vs add-on MTX therapy shows little or no improvement with combination therapy, although the use of concomitant MTX appears to prolong TNF inhibitor drug survival of mAb TNF inhibitors. Registries and observational studies have the potential to fill some of the knowledge gaps in this area.

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)

A white paper--consensus and recommendations of a global harmonization team on assessing the impact of immunogenicity on pharmacokinetic measurements

The Global Bioanalysis Consortium (GBC) set up an international team to explore the impact of immunogenicity on pharmacokinetic (PK) assessments. The intent of this paper is to define the field and propose best practices when developing PK assays for biotherapeutics. We focus on the impact of anti-drug antibodies (ADA) on the performance of PK assay leading to the impact on the reported drug concentration and exposure. The manuscript describes strategies to assess whether the observed change in the drug concentration is due to the ADA impact on drug clearance rates or is a consequence of ADA interference in the bioanalytical method applied to measure drug concentration. This paper provides the bioanalytical scientist guidance for developing ADA-tolerant PK methods. It is essential that the data generated in the PK, ADA, pharmacodynamic and efficacy/toxicity evaluations are viewed together. Therefore, the extent for the investigation of the PK sensitivity to the presence of ADA should be driven by the project needs and risk based.

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.