Long-term measurement of anti-adalimumab using pH-shift-anti-idiotype antigen binding test shows predictive value and transient antibody formation

Clinical consequences of infliximab immunogenicity and the effect of proactive therapeutic drug monitoring: exploratory analyses of the randomised, controlled NOR-DRUM trials

BACKGROUND

Antidrug antibodies to TNF inhibitors might affect clinical outcomes. Proactive therapeutic drug monitoring allows for early detection of antidrug antibodies and might reduce negative clinical consequences. We aimed to explore how antidrug antibodies to the TNF inhibitor infliximab influence treatment outcomes, and to assess the effect of proactive therapeutic drug monitoring.

METHODS

This was a predefined exploratory analysis of data from the randomised, controlled NOR-DRUM trials. The trials were conducted in rheumatology, gastroenterology, and dermatology departments at 21 Norwegian hospitals. Adult patients (aged 18-75 years) with immune-mediated inflammatory diseases were randomly assigned to proactive therapeutic drug monitoring or standard infliximab dosing in the NOR-DRUM A trial (30-week follow-up) and the NOR-DRUM B trial (52-week follow-up). Antidrug antibodies were assessed with a drug-sensitive assay before each infusion. The outcomes of remission (at week 30), disease worsening (during 52 weeks), infusion reactions, and infliximab discontinuation were assessed according to the presence of antidrug antibodies and use of therapeutic drug monitoring.

FINDINGS

Between March 1, 2017, and Dec 12, 2019, 616 patients were included in the NOR-DRUM trials, of whom 615 had at least one serum infliximab and antidrug antibody assessment and were included in the present analyses. Mean age was 45 years (IQR 32-56), 305 (50%) patients were women, and 310 (50%) patients were men. Antidrug antibodies were detected in 147 (24%) patients. Remission at week 30 occurred in 25 (35%) of 72 patients with antidrug antibodies and 180 (54%) of 335 without antidrug antibodies (risk ratio 0·62 [95% CI 0·45-0·86]; p=0·0037). In patients with antidrug antibodies compared with patients without antidrug antibodies, higher rates were found for: disease worsening over 52 weeks (0·76 per person-year vs 0· 35 per person-year, hazard ratio [HR] 2·02 [95% CI 1·33-3·07]; p=0·0009), infusion reactions (0·16 per person-year vs 0·03 per person-year, HR 17·02 [6·98-41·47]; p<0·0001), and infliximab discontinuation (1·00 per person-year vs 0·20 per person-year, HR 6·64 [4·84-9·11]; p<0·0001). These associations were more pronounced in patients with high concentrations of antidrug antibodies than in those with low concentrations of antidrug antibodies. Independent of antibody status, therapeutic drug monitoring was associated with a lower risk of disease worsening (HR 0·41 [0·29-0·59]; p=0·0001) or an infusion reaction (HR 0·30 [0·12-0·73]; p=0·0076), and was associated with an increase in the rate of infliximab discontinuation (HR 1·37 [1·02-1·83]; p=0·037).

INTERPRETATION

In patients where antidrug antibodies were detected, remission was less likely to be reached and sustained, and infusion reaction or discontinuation of infliximab was more likely. Timely detection of antidrug antibodies by proactive therapeutic drug monitoring facilitated treatment decisions that reduced the negative consequences, both regarding infliximab effectiveness and safety. This highlights the role of proactive therapeutic drug monitoring in optimising infliximab therapy.

FUNDING

Inter-regional KLINBEFORSK grants and South-Eastern Norway Regional Health Authority grants.

Surface plasmon resonance assays for the therapeutic drug monitoring of infliximab indicate clinical relevance of anti-infliximab antibody binding properties

OBJECTIVES

The therapeutic antibody infliximab (IFX) has improved the life quality of numerous autoinflammatory disease patients. However, IFX can trigger the generation of anti-drug antibodies (ADA), whose optimal evaluation and management are currently subject of controversial discussions. We present two novel surface plasmon resonance (SPR) biosensor assays for therapeutic drug monitoring of IFX and characterization of ADA and investigated the diagnostic value of ADA binding properties.

METHODS

IFX and ADA were quantified via developed SPR biosensor assays (IFXmon and ADAmon, respectively) and diagnostics-approved ELISA in sera from inflammatory bowel disease patients. Pre-analytic ADA enrichment with magnetic beads enabled analytical drug tolerance of the ADAmon assay. The dissociation ratio (DissR) as an index for ADA:IFX binding stability was calculated from the SPR sensorgrams of ADA quantification runs.

RESULTS

IFX levels determined by IFXmon assay and ELISA showed high agreement, whereas ADA quantification concordance between ADAmon assay and ELISA was poor. In patients, DissR was predominantly constant over time and differed significantly between therapy outcomes. A DissR cut-off of 1.524 indicated undetectable IFX levels with 71.4% sensitivity and 88.9% specificity. Additionally, the SPR reference surface was exploited as serum-individual negative control to check result plausibility within multi-sample run sequences.

CONCLUSIONS

Overall, both SPR biosensor assays exhibited reliable quantitative performance with accuracies superior to their ELISA counterparts and precision inferior to ELISA only for ADAmon. DissR presented itself as promising ADA binding parameter and could contribute to both earlier and more tailored therapeutic decisions.

Statistical Approaches for Establishing Appropriate Immunogenicity Assay Cut Points: Impact of Sample Distribution, Sample Size, and Outlier Removal

The statistical assessments needed to establish anti-drug antibody (ADA) assay cut points (CPs) can be challenging for bioanalytical scientists. Poorly established CPs that are too high could potentially miss treatment emergent ADA or, when set too low, result in detection of responses that may have no clinical relevance. We evaluated 16 validation CP datasets generated with ADA assays at Regeneron's bioanalytical laboratory and compared results obtained from different CP calculation tools. We systematically evaluated the impact of various factors on CP determination including biological and analytical variability, number of samples for capturing biological variability, outlier removal methods, and the use of parametric vs. non-parametric CP determination. In every study, biological factors were the major component of assay response variability, far outweighing the contribution from analytical variability. Non-parametric CP estimations resulted in screening positivity in drug-naïve samples closer to the targeted rate (5%) and were less impacted by skewness. Outlier removal using the boxplot method with an interquartile range (IQR) factor of 3.0 resulted in screening positivity close to the 5% targeted rate when applied to entire drug-naïve dataset. In silico analysis of CPs calculated using different sample sizes showed that using larger numbers of individuals resulted in CP estimates closer to the CP of the entire population, indicating a larger sample size (~ 150) for CP determination better represents the diversity of the study population. Finally, simpler CP calculations, such as the boxplot method performed in Excel, resulted in CPs similar to those determined using complex methods, such as random-effects ANOVA.

Drug-tolerant detection of anti-drug antibodies in an antigen-binding assay using europium chelate fluorescence

Accurate anti-drug antibody (ADA) measurements in patient sera requires dissociation of ADA-drug complexes combined with sensitive and specific ADA detection. Bridging type immunoassays are often used despite several disadvantages associated with this approach. A good drug-tolerant alternative is the acid-dissociation radioimmunoassay (ARIA), but this method is not easily implemented in most labs as specialized facilities are required for working with radioactive materials. We describe an innovative method for ADA detection that combines the advantages of antigen binding tests like the ARIA with the convenience of regular immunoassays. This acid-dissociation lanthanide-fluorescence immunoassay (ALFIA) involves dissociation of ADA-drug complexes, followed by binding to an europium-labeled drug derivative and subsequently an IgG pulldown on Sepharose beads. After europium elution, detection is achieved by measuring time-resolved fluorescence originating from europium chelate complexes. We measured anti-adalimumab ADA levels in sera of 94 rheumatoid arthritis patients using the ALFIA and showed this method to be highly drug tolerant, sensitive and specific for anti-adalimumab ADAs.

Past, Present and (Foreseeable) Future of Biological Anti-TNF Alpha Therapy

Due to the key role of tumor necrosis factor-alpha (TNF-α) in the pathogenesis of immunoinflammatory diseases, TNF-α inhibitors have been successfully developed and used in the clinical treatment of autoimmune disorders. Currently, five anti-TNF-α drugs have been approved: infliximab, adalimumab, golimumab, certolizumab pegol and etanercept. Anti-TNF-α biosimilars are also available for clinical use. Here, we will review the historical development as well as the present and potential future applications of anti-TNF-α therapies, which have led to major improvements for patients with several autoimmune diseases, such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), Crohn's disease (CD), ulcerative colitis (UC), psoriasis (PS) and chronic endogenous uveitis. Other therapeutic areas are under evaluation, including viral infections, e.g., COVID-19, as well as chronic neuropsychiatric disorders and certain forms of cancer. The search for biomarkers able to predict responsiveness to anti-TNF-α drugs is also discussed.

Assessing Immunogenicity of Biologic Drugs in Inflammatory Joint Diseases: Progress Towards Personalized Medicine

Biologic drugs have greatly improved treatment outcomes of inflammatory joint diseases, but a substantial proportion of patients either do not respond to treatment or lose response over time. Drug immunogenicity, manifested as the formation of anti-drug antibodies (ADAb), constitute a significant clinical problem. Anti-drug antibodies influence the pharmacokinetics of the drug, are associated with reduced clinical efficacy, and an increased risk of adverse events such as infusion reactions. The prevalence of ADAb differs among drugs and diseases, and the detection of ADAb also depends on the assay format. Most data exist for the tumor necrosis factor-alpha inhibitors infliximab and adalimumab, with a frequency of ADAb that ranges from 10 to 60% across studies. Measurement of ADAb and serum drug concentrations, therapeutic drug monitoring, has been suggested as a strategy to optimize therapy with biologic drugs. Although the recent randomized clinical Norwegian Drug Monitoring (NOR-DRUM) trials show promise towards a personalized medicine prescribing approach by therapeutic drug monitoring, several challenges remain. A plethora of assay formats, with widely differing properties, is currently used for measuring ADAb. Comparing results between different assays and laboratories is difficult, which complicates the development of cut-offs necessary for guidelines and the implementation of ADAb measurements in clinical practice. With the possible exception of infliximab, limited data on clinical relevance and cost effectiveness exist to support therapeutic drug monitoring as a routine clinical strategy to monitor biologic drugs in inflammatory joint diseases. The aim of this review is to provide an overview of the characteristics and prevalence of ADAb, predisposing factors to ADAb formation, commonly used assessment methods, clinical consequences of ADAb, and the potential implications of ADAb assessments for everyday treatment of inflammatory joint diseases.

Risk factors for anti-drug antibody formation to infliximab: Secondary analyses of a randomised controlled trial

BACKGROUND

Anti-drug antibodies (ADAb) frequently form early in the treatment course of infliximab and other tumour necrosis factor (TNF) inhibitors, leading to treatment failure and adverse events.

OBJECTIVE

To identify risk factors for ADAb in the early phase of infliximab treatment.

METHODS

Patients (n = 410) with immune-mediated inflammatory diseases who initiated infliximab treatment were included in the 38-week Norwegian Drug Monitoring Trial (NOR-DRUM) A and randomised 1:1 to therapeutic drug monitoring (TDM) or standard therapy. Serum levels of infliximab and ADAb were measured at each infusion. Possible risk factors for ADAb formation were assessed using logistic regression, adjusting for potential confounders.

RESULTS

ADAb were detected in 78 (19%) patients. A diagnosis of rheumatoid arthritis (RA) (odds ratio [OR], 1.9 [95% confidence interval [CI] 1.0-3.6]) and lifetime smoking (OR, 2.0 [CI 1.1-3.6]) were baseline risk factors, while baseline use of concomitant immunosuppressors (OR, 0.4 [CI 0.2-0.8]) and a diagnosis of spondyloarthritis (SpA) (OR, 0.4 [CI 0.2-0.8]) reduced the risk of ADAb. Higher disease activity during follow-up (OR, 1.1 [CI 1.0-1.1]) and "drug holidays" of more than 11 weeks (OR, 4.1 [CI 1.2-13.8]) increased the risk of ADAb, whereas higher infliximab doses (OR, 0.1 [CI 0.0-0.3) and higher serum infliximab concentrations (OR, 0.7 [CI 0.6-0.8]) reduced the risk of immunogenicity.

CONCLUSION

Several risk factors for ADAb formation during early-phase infliximab treatment were identified. This knowledge provides a basis for treatment strategies to mitigate the formation of ADAb and identify patients in whom these measures are of particular importance.

Approaches for the detection and analysis of anti-drug antibodies to biopharmaceuticals: A review

Antibody-based therapeutic agents and other biopharmaceuticals are now used in the treatment of many diseases. However, when these biopharmaceuticals are administrated to patients, an immune reaction may occur that can reduce the drug's efficacy and lead to adverse side effects. The immunogenicity of biopharmaceuticals can be evaluated by detecting and measuring antibodies that have been produced against these drugs, or anti-drug antibodies (ADAs). Methods for ADA detection and analysis can be important during the selection of a therapeutic approach based on such drugs and is crucial when developing and testing new biopharmaceuticals. This review examines approaches that have been used for ADA detection, measurement, and characterization. Many of these approaches are based on immunoassays and antigen binding tests, including homogeneous mobility shift assays. Other techniques that have been used for the analysis of ADAs are capillary electrophoresis, reporter gene assays, surface plasmon resonance spectroscopy, and liquid chromatography-mass spectrometry. The general principles of each approach will be discussed, along with their recent applications with regards to ADA analysis. This article is protected by copyright. All rights reserved.

Immunogenicity of biologics used in the treatment of moderate to severe psoriasis

The number of biologic drugs available for the treatment of psoriasis continue to expand. However, being biological proteins and thus potentially immunogenic, there is evidence that anti-drug-antibodies develop against the various therapeutic proteins currently being utilised. Although chimeric antibodies that contain elements of the parental rodent monoclonal antibodies are immunogenic, anti-drug antibodies occur even if the biologic is a fully human protein and these can impact on clinical efficacy and safety. However, there is a wide variation in the reported level of anti-drug-antibodies for the same and different treatments that is highlighting issues with various assays used in anti-drug antibody detection. Here we review the available data on the occurrence of anti-drug antibodies in people with psoriasis treated with biologic agents.

Metreleptin worked in a diabetic woman with a history of hematopoietic stem cell transplantation (HSCT) during infancy: further support for the concept of 'HSCT-associated lipodystrophy'

A 17-year-old woman with a history of childhood leukemia and hematopoietic stem cell transplantation (HSCT), preceded by total body irradiation, developed diabetes, dyslipidemia, fatty liver, and marked insulin resistance. Based on Dunnigan phenotype, HSCT-associated lipodystrophy was suspected. Because of rapid deterioration of diabetes control, metreleptin was introduced at 23 years of age upon receipt of her caregiver's documented consent. This trial was initially planned as a prospective 18 month-long study, with regular assessments of the patient's physical activity, food intake, and body composition analysis. However, because an abrupt and transient attenuation of the metreleptin effect occurred 16 months after the treatment initiation, the entire course of 28 months is reported here. Over the period, her HbA1c decreased from 10.9% to 6.7% despite no significant increase of physical activity and with a stable food intake. Decreased levels of triglyceride and non-HDL cholesterol were found. Her liver function improved, indicating the amelioration of fatty liver. In addition, a 25% reduction in the subcutaneous fat area at umbilical level was found, accompanied by a decrease in fat percentage of both total-body and trunk. The formation of neutralizing antibodies to metreleptin may be responsible for the transient loss of efficacy, considering a sudden elevation in her serum leptin level. In conclusion, metreleptin is useful for the management of HSCT-associated lipodystrophy, supporting the concept that adipose tissue dysfunction is responsible for diverse post-HSCT metabolic aberrations.

Thiopurines: Recent Topics and Their Role in the Treatment of Inflammatory Bowel Diseases

Ulcerative colitis (UC) and Crohn's disease (CD) are chronic inflammatory bowel diseases (IBD) of unknown etiology, characterized by repeated relapse and remission. The efficacy of thiopurine in IBD was first reported in the late 1960s. Thiopurines are used to alleviate the symptoms of IBD, especially UC. These drugs have a steroid-sparing potential and are widely used for the purpose of maintaining long-term remission in steroid-dependent cases. Therefore, thiopurines tend to be used long-term, but adverse events that accompany long-term use, such as lymphoproliferative disorders, must be monitored with care. In contrast, thiopurine plays a critical role in controlling the immunogenicity of biologics. Furthermore, although thiopurine is an old drug, new findings, including the prediction of serious adverse events such as severe alopecia and acute advanced leukopenia, by nudix hydrolase 15 gene polymorphism analysis, as well as the possibility of appropriate drug monitoring by detailed analysis of 6-thioguanine nucleotides have been clarified. However, the consequences of thiopurine withdrawal have not been determined and further studies, including randomized controlled trials, are necessary to answer the clinical question regarding the scenarios in which thiopurine withdrawal is possible.

Assessment of clinically relevant immunogenicity for mAbs; are we over reporting ADA?

Immunogenicity is recognized as a possible clinical risk due to the development of anti drug antibodies (ADAs) that can adversely impact drug safety and efficacy. Although robust assays are currently used to assess the ADA, there is a debate on how best to generate the most appropriate immunogenicity data. There are several factors that can trigger ADA formation including the immunity status of the target population and the severity of the disease indication. Immunogenicity testing has defaulted to the most conservative approach regardless of the inherent risk of the molecule or the patient population. For low-risk biotherapeutics such as human monoclonal antibodies, ADA data that provide clinically relevant information should be prioritized when establishing immunogenicity monitoring plans.

Immunogenicity of TNF-Inhibitors

Tumor necrosis factor inhibitors (TNFi) have significantly improved treatment outcome of rheumatic diseases since their incorporation into treatment protocols two decades ago. Nevertheless, a substantial fraction of patients experiences either primary or secondary failure to TNFi due to ineffectiveness of the drug or adverse reactions. Secondary failure and adverse events can be related to the development of anti-drug antibodies (ADA). The earliest studies that reported ADA toward TNFi mainly used drug-sensitive assays. Retrospectively, we recognize this has led to an underestimation of the amount of ADA produced due to drug interference. Drug-tolerant ADA assays also detect ADA in the presence of drug, which has contributed to the currently reported higher incidence of ADA development. Comprehension and awareness of the assay format used for ADA detection is thus essential to interpret ADA measurements correctly. In addition, a concurrent drug level measurement is informative as it may provide insight in the extent of underestimation of ADA levels and improves understanding the clinical consequences of ADA formation. The clinical effects are dependent on the ratio between the amount of drug that is neutralized by ADA and the amount of unbound drug. Pharmacokinetic modeling might be useful in this context. The ADA response generally gives rise to high affinity IgG antibodies, but this response will differ between patients. Some patients will not reach the phase of affinity maturation while others generate an enduring high titer high affinity IgG response. This response can be transient in some patients, indicating a mechanism of tolerance induction or B-cell anergy. In this review several different aspects of the ADA response toward TNFi will be discussed. It will highlight the ADA assays, characteristics and regulation of the ADA response, impact of immunogenicity on the pharmacokinetics of TNFi, clinical implications of ADA formation, and possible mitigation strategies.

Adalimumab drug and antidrug antibody levels do not predict flare risk after stopping adalimumab in RA patients with low disease activity

OBJECTIVE

To establish whether serum adalimumab (ADA) trough level (ADA-TL) and antidrug antibody (ADA-ab) level predict flare after stopping ADA in established RA patients with long-standing low disease activity.

METHODS

From the clinical trial Potential Optimalisation and Effectiveness of TNF-blockers, 210 RA patients stopping ADA, who had been using ADA (40 mg/2 weeks) for >1 year with conventional synthetic DMARDs and who had low disease activity (DAS28 < 3.2, or the rheumatologist's assessment of low disease activity with CRP < 10 mg/l) for at least 6 months prior to stopping, were followed for 1 year. The ADA-TL was measured (by ELISA) 12-17 days after the last ADA injection; if it was low, ADA-abs were measured (by an antigen-binding test). Association between time-to-flare and ADA-TL was evaluated by area under the receiver operating characteristic curve and Cox regression.

RESULTS

A total of 106 (51%) patients flared within 1 year after stopping ADA. The area under the receiver operating characteristic curve for flare and ADA-TL was 0.50 (95% CI 0.42-0.58), P = 0.92. The hazard ratio for flare for ADA-TL ⩾ 5 μg/ml (adequate level) vs <5 μg/ml was 0.93 (95% CI: 0.63-1.36) (not significant). Of the 4 patients with high ADA-ab levels, 2 patients (50%) experienced a flare.

CONCLUSION

Flare risk within the year following stopping ADA is not predicted by the ADA-TL or ADA-abs assessed at the moment of stopping.

TRIAL REGISTRATION

Netherlands Trial Register, http://www.trialregister.nl, NTR3112.

Evaluation von Immunoassays zum Nachweis von Anti-Drug Antikörpern gegen Infliximab und korrespondierenden Infliximab Serumspiegeln bei Spondyloarthritis im klinischen Alltag

Hintergrund TNF-α-Inhibitoren sind wirksame Medikamente bei vielen chronisch-inflammatorischen Erkrankungen. Trotz eines akzeptablen Wirkansprechens gibt es einen beachtlichen Anteil an Patienten, bei denen ein primärer oder sekundärer Wirkverlust beobachtet wird. Eine mögliche Erklärung für das fehlende Therapieansprechen wird in der Immunogenität von Biologika gesehen. Die resultierenden Anti-Drug-Antikörper (ADA) können die Wirkung der Biologika abschwächen und/oder unerwünschte Arzneimittelwirkungen hervorrufen.

Ziel Durch diese Arbeit sollten 2 neue Testverfahren zum Nachweis von ADA gegen Infliximab und die korrespondierenden Serumspiegel evaluiert werden. Dazu gehört ebenfalls die Klärung der Praktikabilität eines therapeutischen Drugmonitorings (TDM) sowie das Erfassen von ADA assoziierten Nebenwirkungen und Therapieversagen für den klinischen Alltag. Es sollte eine Einschätzung darüber gegeben werden, welche Effekte das Auftreten von ADA auf den Medikamentenspiegel und den Verlauf von entzündlich-rheumatischen Erkrankungen im Rahmen der Verlaufsuntersuchungen hat.

Patienten und Methodik Die vorliegende Studie umfasst 30 mit Infliximab behandelte Patienten (30% weiblich, mittleres Alter 55,5 Jahre, min. 33 Jahre, max. 73 Jahre) mit zuvor gesicherter PsA (20%) oder axialer SpA (80%). Bei 36,7% bestand eine Begleitmedikation mit einem konventionellen Basistherapeutikum (cDMARD). Bei den vorhandenen Proben wurden zu 2 Zeitpunkten (ZP) der Serumspiegel des Therapieantikörpers, sowie die totalen ADA (tADA) und freien ADA (fADA) mittels Enzyme-Linked-Immuno-Sorbent-Assay (ELISA) bestimmt und in Zusammenhang mit der Krankheitsaktivität gesetzt. Weiter wurde die Inter-Assay-Variabilität untersucht.

Ergebnisse Bei 19 Patienten (63,3%) wurden positive tADA nachgewiesen, bei 13 Patienten (43,3%) auch fADA. Bei Nachweis von positiven tADA fanden sich zu 94,7% zeitweise subtherapeutische Infliximabkonzentrationen. Hohe tADA Titer gingen mit einer höheren Krankheitsaktivität einher. fADA traten nur bei mittleren bis hohen tADA-Titern auf. Bei 30% der Patienten fanden sich tADA trotz klinischer Remission der Erkrankung. Zwischen den beiden Assays zur Erfassung des Infliximab Serumspiegels gab es zu beiden Messzeitpunkten eine hohe Interassay-Übereinstimmung (1. ZP r=0,78, p=0,01; 2. ZP r=0,96, p=0,01).

Schlussfolgerungen Eine Erfassung von ADA sollte im Kontext mit den korrespondierenden Medikamenten-Serumspiegeln im Rahmen der Verlaufsuntersuchungen erfolgen, um relevante Informationen für das Monitoring einer Infliximabtherapie im klinischen Alltag zu erhalten. Bei der Untersuchung auf ADA sollte zwischen niedrigen und hohen tADA unterschieden werden, da hohe Spiegel mit dem Auftreten von fADA und erhöhter Krankheitsaktivität assoziiert sind. Die Ergebnisse müssen jedoch immer auf den individuellen Fall im Zusammenhang mit der klinischen Situation bezogen werden, da ADA sogar bei klinischer Remission auftreten können.

Association of Serum Ustekinumab Levels With Clinical Response in Psoriasis

Question

Can therapeutic drug monitoring for the interleukin-12 and interleukin-23 inhibitor ustekinumab optimize treatment pathways and outcomes in patients with psoriasis?

Findings

This cohort study of 491 patients with psoriasis found that early serum ustekinumab levels were associated with a subsequent 75% reduction from baseline in Psoriasis Area and Severity Index score, although this association did not hold across other Psoriasis Area and Severity Index outcomes. Drug immunogenicity appeared to be low, with antidrug antibodies detected in only 17 of 490 patients (3.5%).

Meaning

This study provides evidence that measurement of early ustekinumab levels could be useful to direct treatment strategy in patients with psoriasis; adequate drug exposure early in the treatment cycle may be particularly important in determining clinical outcome.

Importance

High-cost biologic therapies have transformed the management of immune-mediated inflammatory diseases. To optimize outcomes and reduce costs, dose adjustment informed by measurement of circulating drug levels has been shown to be effective in various settings. However, limited evidence exists for this approach with the interleukin 12 and interleukin 23 inhibitor ustekinumab.

Objective

To evaluate clinical utility of therapeutic drug monitoring for ustekinumab in patients with psoriasis.

Design, Setting, and Participants

A prospective observational cohort of 491 adults with psoriasis was recruited to the multicenter Biomarkers of Systemic Treatment Outcomes in Psoriasis study within the British Association of Dermatologists Biologic and Immunomodulators Register from June 2009 to December 2017; samples from some patients were taken between 2009 and 2011 as part of a pilot study with the same inclusion criteria.

Exposure

Serum ustekinumab level measured at any point during the dosing cycle using an enzyme-linked immunosorbent assay.

Main Outcomes and Measures

Disease activity measured using the Psoriasis Area and Severity Index (PASI) score. Treatment response outcomes were PASI75 (75% reduction in PASI score from baseline [primary outcome]), PASI90 (90% reduction of PASI score from baseline), and absolute PASI score of 1.5 or less.

Results

A total of 491 patients (171 women and 320 men; mean [SD] age, 45.7 [12.8] years) had 1 or more serum samples (total, 853 samples obtained 0-56 weeks from start of treatment) and 1 or more PASI scores within the first year of treatment. Antidrug antibodies were detected in only 17 of 490 patients (3.5%). Early measured drug levels (1-12 weeks after starting treatment) were associated with PASI75 response 6 months after starting treatment (odds ratio, 1.38; 95% CI, 1.11-1.71) when adjusted for baseline PASI score, age, and ustekinumab dose. However, this finding was not consistent across the other PASI outcomes (PASI90 and PASI score of ≤1.5).

Conclusions and Relevance

This real-world study provides evidence that measurement of early serum ustekinumab levels could be useful to direct the treatment strategy for psoriasis. Adequate drug exposure early in the treatment cycle may be particularly important in determining clinical outcome.

Clinical Pharmacokinetics and Pharmacodynamics of Infliximab in the Treatment of Inflammatory Bowel Disease

Infliximab was the first monoclonal antibody to be approved for the treatment of pediatric and adult patients with moderately to severely active Crohn's disease (CD) and ulcerative colitis (UC). It has been shown to induce and maintain both clinical remission and mucosal healing in pediatric and adult patients with inflammatory bowel disease (IBD) who are unresponsive or refractory to conventional therapies. The administration of infliximab is weight-based and the drug is administered intravenously. The volume of distribution of infliximab is low and at steady state ranges from 4.5 to 6 L. Therapeutic monoclonal antibodies, such as immunoglobulins, are cleared from the circulation primarily by catabolism. Median infliximab half-life is approximately 14 days. Infliximab concentration-time data in patients with CD and UC have been shown to be highly variable within an individual patient over time and between individuals by multiple population pharmacokinetic models. Covariates that have been identified to account for a part of the observed inter- and intra-individual variability in clearance are the presence of antidrug antibodies, use of concomitant immunomodulators, degree of systemic inflammation, serum albumin concentration, and body weight, which can affect the pharmacodynamic response. This article provides a comprehensive review of the clinical pharmacokinetics and pharmacodynamics of infliximab, as well as the role of therapeutic drug monitoring in the treatment of IBD.

Immunogenicity of Protein Pharmaceuticals

Protein therapeutics have drastically changed the landscape of treatment for many diseases by providing a regimen that is highly specific and lacks many off-target toxicities. The clinical utility of many therapeutic proteins has been undermined by the potential development of unwanted immune responses against the protein, limiting their efficacy and negatively impacting its safety profile. This review attempts to provide an overview of immunogenicity of therapeutic proteins, including immune mechanisms and factors influencing immunogenicity, impact of immunogenicity, preclinical screening methods, and strategies to mitigate immunogenicity.

Therapeutic drug monitoring of tumour necrosis factor inhibitors in the management of chronic inflammatory diseases

Tumour necrosis factor inhibitor therapy has drastically changed the management of chronic inflammatory diseases. Some important drawbacks that can cause loss of response during treatment with these drugs are related to their large individual variability, the disease burden and the formation of antidrug antibodies that increase its clearance. Therapeutic drug monitoring of these drugs is not yet recommended by all scientific societies, and if so, only in patients with inflammatory symptoms. Proactive therapeutic drug monitoring represents a new strategy with many potential clinical benefits, including the prevention of immunogenicity, a reduction in the need for rescue therapy and greater durability of tumour necrosis factor inhibitor treatment. The review is based on a systematic search of the literature for controlled trials, systematic reviews, experimental studies, guideline papers and cohort studies addressing the best practice in tumour necrosis factor inhibitor therapeutic drug monitoring. Although there is ample evidence supporting the use of therapeutic drug monitoring in clinical practice to achieve better outcomes, some challenges have been detected. Many studies are focused on finding solutions for the lack of standardization of analytical methods to measure tumour necrosis factor inhibitor and antidrug antibodies concentrations. Other challenges are development of effective cost-saving proactive algorithms to identify optimal drug concentrations and the research on the role of antidrug antibodies, especially in the management and prevention of loss of response. Therapeutic drug monitoring of tumour necrosis factor inhibitor offers a rational approach to the optimization of the treatment of chronic inflammatory disease. Although prospective controlled trials yield little conclusive evidence of its benefits, there is growing acceptance of its value in clinical practice.

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.

Drug immunogenicity in patients with inflammatory arthritis and secondary failure to tumour necrosis factor inhibitor therapies: the REASON study

Objectives

The aims were to evaluate the prevalence of anti-drug antibodies (ADA) in patients with RA or SpA experiencing secondary failure to anti-TNF therapy and to correlate ADA presence with anti-TNF concentration and clinical response.

Methods

This was a cross-sectional, observational study of patients with active RA or SpA experiencing secondary failure to etanercept (ETN), infliximab (INF) or adalimumab (ADL). Concomitant non-biologic DMARDs were permitted. Serum anti-TNF and ADA levels were measured with two-site ELISA.

Results

Among 570 evaluable patients, those with RA (n = 276) were mostly female (80 vs 39%), older (56 vs 48 years), received concomitant DMARDs (83 vs 47%) and had maintained good clinical disease control for longer (202 vs 170 weeks) compared with patients with SpA (n = 294). ADA were found in 114/570 (20.0%) patients; 51/188 (27.1%) against INF and 63/217 (29.0%) against ADL; none against ETN. Of these 114 patients, 92 (81%) had no detectable serum drug concentrations. Proportionately more patients with SpA (31.3%) had anti-INF antibodies than those with RA (21.1%; P = 0.014). A significantly lower proportion of patients receiving concomitant DMARDs (16.5%) developed ADA than those on monotherapy (26.4%; P < 0.05).

Conclusion

In patients with RA or SpA and secondary failure, the development of ADA against ADL or INF, but not ETN, appears to be one of the main reasons for secondary treatment failure, but not the only one. Further investigations are needed to determine other causes of anti-TNF failure.

Clinical relevance of detecting anti-infliximab antibodies with a drug-tolerant assay: post hoc analysis of the TAXIT trial

OBJECTIVE

To evaluate the clinical relevance of antidrug antibodies (ADAs) measured using a drug-tolerant assay in a post hoc analysis of the Trough Concentration (TC) Adapted Infliximab Treatment (TAXIT) randomised controlled trial.

DESIGN

ADA in serum samples (n=221) of 76 patients enrolled in TAXIT, who presented with an infliximab TC <3 µg/mL at screening, were reanalysed after optimisation and at the end of the study using a drug-tolerant ADA assay. Patients underwent dose escalation to achieve therapeutic TCs between 3 µg/mL and 7 µg/mL prior to randomisation. Patients were grouped into quartiles (Q1-4) according to ADA concentration at screening.

RESULTS

Using a drug-tolerant assay, the immunogenicity detection rate increased from 21% (drug-sensitive assay) to 63% at screening, from 0% to 51% after optimisation and from 3% to 42% at the end of TAXIT. Patients in ADA Q4 required a higher cumulative infliximab dose (2390 (880-2998) mg) to achieve target TCs, resulting in a higher drug cost (€10 712 (4120-13 596)) compared with ADA-negative patients (€2060 (1648-3296)) and patients in ADA Q1/Q2 (€2060 (1648-4120)/€2060 (1751-3296), p<0.001). However, all but one patient belonging to ADA Q4 were also ADA-positive using a drug-sensitive assay.

CONCLUSIONS

Upon dose intensification, low concentration ADAs, not detectable using a drug-sensitive assay, disappear in more than half of the patients over time and are clinically non-relevant. In contrast, high concentration ADAs which are typically also detected in a drug-sensitive assay, persist over time and necessitate a higher cumulative dose and drug cost. In the latter group, proactive drug switching may be more cost-efficient.

CLINICAL TRIALS REGISTER

2011-002061-38; Post-results.

Immunogenicity of Therapeutic Antibodies: Monitoring Antidrug Antibodies in a Clinical Context

One of the factors that may impact drug levels of therapeutic antibodies in patients is immunogenicity, with potential loss of efficacy. Nowadays, many immunogenicity assays are available for testing antidrug antibodies (ADA). In this article, we discuss different types of immunogenicity assays and their clinical relevance in terms of drug tolerance, relation with pharmacokinetics (PK), neutralizing antibodies, potential adverse events associated with ADA, and prediction of ADA production. Drug-tolerant assays can provide insight into the process of immunogenicity, but for clinical management, these assays do not necessarily outperform drug-sensitive assays. The usefulness of any ADA assay for clinical decision making will be larger when drug concentrations are also measured, and this is true, in particular, for drug-tolerant assays.

Consensus-based recommendations for the use of biosimilars to treat rheumatological diseases

The study aimed to develop evidence-based recommendations regarding the evaluation and use of biosimilars to treat rheumatological diseases. The task force comprised an expert group of specialists in rheumatology, dermatology and gastroenterology, and pharmacologists, patients and a regulator from ten countries. Four key topics regarding biosimilars were identified through a process of discussion and consensus. Using a Delphi process, specific questions were then formulated to guide a systematic literature review. Relevant English-language publications through November 2016 were searched systematically for each topic using Medline; selected papers and pertinent reviews were examined for additional relevant references; and abstracts presented at the 2015 and 2016 American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) annual scientific meetings were searched for those about biosimilars. The experts used evidence obtained from these studies to develop a set of overarching principles and consensus recommendations. The level of evidence and grade of recommendation were determined for each. By the search strategy, 490 references were identified. Of these, 29 full-text papers were included in the systematic review. Additionally, 20 abstracts were retrieved from the ACR and EULAR conference abstract databases. Five overarching principles and eight consensus recommendations were generated, encompassing considerations regarding clinical trials, immunogenicity, extrapolation of indications, switching between bio-originators and biosimilars and among biosimilars, and cost. The level of evidence and grade of recommendation for each varied according to available published evidence. Five overarching principles and eight consensus recommendations regarding the evaluation and use of biosimilars to treat rheumatological diseases were developed using research-based evidence and expert opinion.

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.

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

Background:

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

Aims:

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

Methods:

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

Results:

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

Conclusions:

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

Genetics of rheumatoid arthritis susceptibility, severity, and treatment response

A decade after the first genome-wide association study in rheumatoid arthritis (RA), a plethora of genetic association studies have been published on RA and its clinical or serological subtypes. We review the major milestones in the study of the genetic architecture of RA susceptibility, severity, and response to treatment. We set the scientific context necessary for non-geneticists to understand the potential clinical applications of human genetics and its significance for a stratified approach to the management of RA in the future.

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.

Assessing the Immunogenicity of Biopharmaceuticals

Biopharmaceuticals have the potential to raise an immunogenic response in treated individuals, which may impact the efficacy and safety profile of these drugs. As a result, it is essential to evaluate immunogenicity throughout the different phases of the clinical development of a biopharmaceutical, including post-marketing surveillance. Although rigorous evaluation of biopharmaceutical immunogenicity is required by regulatory authorities, there is a lack of uniform standards for the type, quantity, and quality of evidence, and for guidance on experimental design for immunogenicity assays or criteria to compare immunogenicity of biopharmaceuticals. Moreover, substantial technological advances in methods to assess immune responses have yielded higher immunogenicity rates with modern assays, and limit comparison of immunogenicity of biopharmaceuticals outside of head-to-head clinical trials. Accordingly, research programs, regulatory agencies, and clinicians need to keep pace with continuously evolving analyses of immunogenicity. Here, we review factors associated with immunogenicity of biopharmaceuticals, potential clinical ramifications, and current regulatory guidance for evaluating immunogenicity, and discuss methods to assess immunogenicity in non-clinical and clinical studies. We also describe special considerations for evaluating the immunogenicity of biosimilar candidates.

Prevalence of Anti-infliximab Antibodies and Their Associated Co-factors in Children with Refractory Arthritis and/or Uveitis: A Retrospective Longitudinal Cohort Study

Objective.

Infliximab (IFX) is a monoclonal tumor necrosis factor-α–inhibiting antibody used in children with refractory arthritis and uveitis. Immunogenicity is associated with a lack of clinical response and infusion reactions in adults; data on immunogenicity in children treated with IFX for rheumatic diseases are scarce. We aimed to describe the prevalence of anti-IFX antibodies and determine co-factors associated with anti-IFX antibodies in children with inflammatory rheumatic and ocular diseases.

Methods.

Consecutive children treated between August 2009 and August 2012 with IFX at our department were included. Blood samples were collected every 6 months before IFX infusion and tested for anti-IFX antibodies by radioimmunoassay. Patients’ charts were retrospectively reviewed for clinical features and analyzed for associations with anti-IFX antibodies.

Results.

Anti-IFX antibodies occurred in 14/62 children (23%) and 32/253 blood samples (12.6%) after a mean treatment time of 1084 days (range 73–3498). Infusion reactions occurred in 10/62 (16%) children during the treatment period. With continuation of IFX, anti-IFX antibodies disappeared in 7/14 children. In the bivariate analysis, the occurrence of anti-IFX antibodies was associated with younger age at IFX treatment start (mean age 7.01 vs 9.88 yrs, p = 0.003) and infusion reactions (OR 15.0), while uveitis as treatment indication was protective against development of anti-IFX antibodies (OR 0.17), likely because of higher IFX doses. In the multivariate logistic regression, all 3 covariates remained highly significant.

Conclusion.

Anti-IFX antibodies occurred commonly at any time during IFX treatment. Anti-IFX antibodies were associated with younger age at IFX start, infusion reactions, and arthritis as treatment indication.

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.

Anti-adalimumab antibodies in psoriasis: lack of clinical utility and laboratory evidence

OBJECTIVE

Adalimumab has proven effective in psoriasis; however, secondary failure may result from the drug's immunogenicity. Prevalence data on the immunogenicity of biologicals, and of adalimumab in particular, are highly variable. We investigated the prevalence of anti-adalimumab antibodies and the association with clinical indexes and tumour necrosis factor α (TNFα) serum levels in psoriatic patients.

DESIGN

Case-control, longitudinal.

SETTING

Single centre.

PARTICIPANTS

Patient groups: I (n=20) receiving biological therapies after switching from adalimumab; II (n=30) ongoing adalimumab therapy; III (n=30) novel adalimumab therapy; IV (n=15) biological therapies other than adalimumab.Healthy subjects: (group V; n=15) never treated with immunosuppressants or biologicals.

INTERVENTIONS

All groups were tested at enrolment. Group II was also tested at 12 months, and group III at 1, 3, and 6 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

Standard clinical evaluations (Psoriasis Area Severity Index (PASI)), blood samples and two-site ELISA-based measurement of serum adalimumab trough levels, anti-adalimumab antibodies and TNFα.

RESULTS

The false-positive rate was 23% for adalimumab detection and 22% for anti-adalimumab antibodies in patients naïve to adalimumab. Spurious positivity for anti-adalimumab antibodies (one-time-point positivity in group III during follow-up) accounted for 33% of the total. The prevalence of anti-drug antibodies was highest (87%) in group I patients. No correlations were found between the presence of anti-adalimumab antibodies or adalimumab levels and changes in PASI scores.

CONCLUSIONS

High variability of results, high prevalence of false-positives and lack of association between anti-adalimumab antibodies and TNFα level/PASI score limit this assay's usefulness. Accurate clinical evaluation is key to early identification of treatment failures.

Validation of a Drug-Resistant Anti-Adalimumab Antibody Assay to Monitor Immunogenicity in the Presence of High Concentrations of Adalimumab

With respect to patient safety and long-term efficacy, immunogenicity of therapeutic antibodies remains an important issue. Pre-treatment of samples using either higher temperature or acidification in order to separate drug/anti-drug antibody complexes has been implemented in the traditional bridging assay and an in-house-developed affinity capture elution assay but only a limited drug tolerance was obtained. In this study, we aim to apply a drug-resistant anti-drug antibody assay to adalimumab through a combination of adalimumab/anti-adalimumab antibody complex precipitation and acid dissociation. A linear dose-response curve ranging from 3.1 to 200 ng/mL was obtained in 1/125 diluted serum, allowing detection of anti-adalimumab antibody concentrations up to 25 μg/mL equivalents MA-ADM6A10, a calibrator anti-adalimumab antibody. The cut-off point for detection was determined using 16 samples of adalimumab naïve patients and set at 0.39 μg/mL equivalents. Validation of the assay revealed that no detectable anti-adalimumab antibody concentrations were found in samples with either a positive anti-infliximab antibody concentration, a physiologic concentration of TNFα, or a high concentration of rheumatoid factor. Full recoveries were obtained when various concentrations of adalimumab (0, 1, 10, and 50 μg/mL) were spiked to 1, 2, and 4 μg/mL of MA-ADM6A10. Spiking of 50 μg/mL adalimumab to eight individual sera revealed similar anti-adalimumab antibody concentrations as in the absence of adalimumab, with a Pearson r correlation of 0.99 and an interclass correlation of 0.99. The assay allows accurate evaluation of adalimumab immunogenicity during induction or upon dose intensification and in serum samples not taken at trough.

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.

How the immune system responds to therapeutic biological agents

Biological agents target disease mechanisms and have modified the natural history of several immune-mediated disorders. Biological agents are structurally immunogenic, and therefore usually elicit a minor, subclinical and transient phenomenon. Occasionally, however, these drugs induce complete cellular and humoral immune responses, with the main clinical consequences being hypersensitivity reactions or loss of treatment response. This article considers the relative pathogenic mechanisms influencing immunogenicity in biological agents and discusses mechanisms of tolerance and adaptive immune response, including adaptive T-regulatory cell induction and immune response induction. Methods of determining cellular and humoral immune response to biological agents are identified and examined. Assays to detect antidrug antibodies and their isotypes can assist in monitoring immunogenicity and in preventing adverse events. Such strategies also enable resource conservation and may provide regulatory authorities with new insights that can be useful during the process of approving new biological or biosimilar agents.

Emerging Technologies and Generic Assays for the Detection of Anti-Drug Antibodies

Anti-drug antibodies induced by biologic therapeutics often impact drug pharmacokinetics, pharmacodynamics response, clinical efficacy, and patient safety. It is critical to assess the immunogenicity risk of potential biotherapeutics in producing neutralizing and nonneutralizing anti-drug antibodies, especially in clinical phases of drug development. Different assay methodologies have been used to detect all anti-drug antibodies, including ELISA, radioimmunoassay, surface plasmon resonance, and electrochemiluminescence-based technologies. The most commonly used method is a bridging assay, performed in an ELISA or on the Meso Scale Discovery platform. In this report, we aim to review the emerging new assay technologies that can complement or address challenges associated with the bridging assay format in screening and confirmation of ADAs. We also summarize generic anti-drug antibody assays that do not require drug-specific reagents for nonclinical studies. These generic assays significantly reduce assay development efforts and, therefore, shorten the assay readiness timeline.

Time Course and Clinical Implications of Development of Antibodies Against Adalimumab in Patients With Inflammatory Bowel Disease

BACKGROUND

Antibodies (Abs) against adalimumab (ADL) have been associated with low ADL levels and treatment failure.

AIM

To characterize the temporal characteristics of anti-ADL Ab appearance and possible disappearance, and determine the clinical significance on drug efficacy and disease course.

METHODS

Cohort study including inflammatory bowel disease patients in whom anti-ADL Abs had been assessed by radioimmunoassay (RIA) and, in case of disappearance, by enzyme immunoassay, and functional reporter gene assay.

RESULTS

Anti-ADL Abs were evaluated in 133 serum samples from 72 patients. Seventeen patients (24%) tested positive after median of 194 days, interquartile range of 66 to 361. The proportion with anti-ADL Abs was 22% after 1 year, and 32% from 21 months onwards. Anti-ADL Abs generally persisted at repeat assessments during continued ADL therapy (n=8). Disappearance of anti-ADL Abs during therapy (n=3) was presumably caused by methodological biases due to detection of nonfunctional nonpersistent anti-ADL Abs by RIA, or false-negative measurement at reassessment by RIA and reporter gene assay. Anti-ADL Abs appeared pharmacologically active as judged by a median ADL concentration below limit of detection versus 7.4 μg/mL in anti-ADL Ab-negative samples (P<0.0001). Anti-ADL Abs associated with loss of response (odds ratio estimated 67, P<0.0001), and shorter treatment duration (P<0.0001).

CONCLUSIONS

Abs against ADL appear in approximately one fourth of inflammatory bowel disease patients with decreasing frequency over time and usually within 1 year of therapy. Anti-ADL Abs generally persist during continued ADL therapy, and are associated with elimination of drug and treatment failure. Therefore, ADL cessation should be considered when anti-ADL Abs are detected and supported by clinical observations.

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

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

Variability in Golimumab Exposure: A 'Real-Life' Observational Study in Active Ulcerative Colitis

BACKGROUND AND AIMS

Golimumab has been approved recently to treat refractory moderate-to-severe ulcerative colitis [UC]. To date it is not clear why a considerable fraction of patients do not respond, or lose initial response, to golimumab therapy. Our aim was to investigate whether a low golimumab serum concentration and/or a positive anti-golimumab antibody status reduces the efficacy of this drug in patients with UC.

METHODS

Serum samples of 21 patients with moderate-to-severe UC were collected during the first 14 weeks of golimumab therapy. For measurement of golimumab serum concentrations, both a tumour necrosis factor [TNF]-coated enzyme-linked immunosorbent assay [ELISA] and a sandwich-type ELISA were developed. Anti-golimumab antibodies were measured using a bridging ELISA and a newly-developed drug-tolerant immunoassay. Clinical response and mucosal healing were assessed 14 weeks after start of treatment.

RESULTS

Out of 21 patients, 10 [48%] reached partial clinical response at Week 14. Median [interquartile range] serum golimumab concentration was significantly higher in partial clinical responders than in non-responders: 10.0 [7.8-10.5] µg/ml versus 7.4 [4.8-8.3] µg/ml at Week 2 [p = 0.035] and 5.1 [4.0-7.9] µg/ml versus 2.1 [1.8-4.2] µg/ml at week 6 [p = 0.037]. Four out of 21 UC patients developed anti-golimumab antibodies, detectable only using a drug-tolerant immunoassay, and three had a partial clinical response at that time. Clinical non-responders had a significantly more severe colitis, indicated by a higher endoscopic Mayo score at baseline compared with partial clinical responders [p = 0.048].

CONCLUSION

Adequate exposure to golimumab drives clinical response. A worse disease at baseline influences clinical response rate negatively.

Validation of a sample pretreatment protocol to convert a drug-sensitive into a drug-tolerant anti-infliximab antibody immunoassay

A meta-analysis revealed that up to 51% of patients treated with infliximab develop anti-drug Abs (ADA) which are associated with loss of response. Detection of ADA is strongly influenced by assay technique since drug-sensitive ADA assays are not able to detect ADA in the presence of drug and therefore underestimate ADA development. In addition, the lack of a calibrator antibody that can be used in a drug-sensitive and drug-tolerant assay hampers an adequate comparison among different assays. Here we present a sample pretreatment protocol to convert the bridging assay, originally developed as a drug-sensitive assay, into a drug-tolerant assay, allowing use of the same assay and calibrator antibody MA-IFX10F9. Using the sample pretreatment protocol, the bridging assay detects antibodies towards infliximab in samples containing up to 5-fold infliximab over anti-infliximab. Analysis of consecutive serum samples from infliximab treated patients revealed that the drug-tolerant assay detects ADA development up to 40 weeks earlier compared to the drug-sensitive assay. In conclusion, the sample pretreatment protocol can be implemented in various assay formats and allows determination of ADA in the presence of drug, providing the possibility for early treatment optimization. Copyright © 2016 John Wiley & Sons, Ltd.