Systematic comparison of drug-tolerant assays for anti-drug antibodies in a cohort of adalimumab-treated rheumatoid arthritis patients

Immunogenicity and Loss of Effectiveness of Biologic Therapy for Inflammatory Bowel Disease Patients Due to Anti-Drug Antibody Development

Many patients with inflammatory bowel disease (IBD) experience a loss of effectiveness to biologic therapy (i.e., anti-TNF therapy, etc.). Therefore, in addition to the adverse effects of the treatment, these patients also face failure to achieve and maintain remission. Immunogenicity, the process of production of antibodies to biological agents, is fundamental to the evolution of loss of response to treatment in IBD patients. The presence of these antibodies in patients is linked to decreased serum drug levels and inhibited biological activity. However, immunogenicity rates exhibit significant variability across inflammatory disease states, immunoassay formats, and time periods. In this review, we aimed to elucidate the immunogenicity and immune mechanisms of antibody formation to biologics, the loss of therapy response, clinical results of biological treatment for IBD from systematic reviews and meta-analyses, as well as to summarize the most recent strategies for overcoming immunogenicity and approaches for managing treatment failure in IBD.

Early At-Home Measurement of Adalimumab Concentrations to Guide Anti-TNF Precision Dosing: A Pilot Study

BACKGROUND AND OBJECTIVE

Underdosing of adalimumab can result in non-response and poor disease control in patients with rheumatic disease or inflammatory bowel disease. In this pilot study we aimed to predict adalimumab concentrations with population pharmacokinetic model-based Bayesian forecasting early in therapy.

METHODS

Adalimumab pharmacokinetic models were identified with a literature search. A fit-for-purpose evaluation of the model was performed for rheumatologic and inflammatory bowel disease (IBD) patients with adalimumab peak (first dose) and trough samples (first and seventh dose) obtained by a volumetric absorptive microsampling technique. Steady state adalimumab concentrations were predicted after the first adalimumab administration. Predictive performance was calculated with mean prediction error (MPE) and normalised root mean square error (RMSE).

RESULTS

Thirty-six patients (22 rheumatologic and 14 IBD) were analysed in our study. After stratification for absence of anti-adalimumab antibodies, the calculated MPE was -2.6% and normalised RMSE 24.0%. Concordance between predicted and measured adalimumab serum concentrations falling within or outside the therapeutic window was 75%. Three patients (8.3%) developed detectable concentrations of anti-adalimumab antibodies.

CONCLUSION

This prospective study demonstrates that adalimumab concentrations at steady state can be predicted from early samples during the induction phase.

CLINICAL TRIAL REGISTRATION

The trial was registered in the Netherlands Trial Register with trial registry number NTR 7692 ( www.trialregister.nl ).

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.

Development of antidrug antibodies against adalimumab maps to variation within the HLA-DR peptide-binding groove

Targeted biologic therapies can elicit an undesirable host immune response characterized by the development of antidrug antibodies (ADA), an important cause of treatment failure. The most widely used biologic across immune-mediated diseases is adalimumab, a tumor necrosis factor inhibitor. This study aimed to identify genetic variants that contribute to the development of ADA against adalimumab, thereby influencing treatment failure. In patients with psoriasis on their first course of adalimumab, in whom serum ADA had been evaluated 6-36 months after starting treatment, we observed a genome-wide association with ADA against adalimumab within the major histocompatibility complex (MHC). The association signal mapped to the presence of tryptophan at position 9 and lysine at position 71 of the HLA-DR peptide-binding groove, with both residues conferring protection against ADA. Underscoring their clinical relevance, these residues were also protective against treatment failure. Our findings highlight antigenic peptide presentation via MHC class II as a critical mechanism in the development of ADA against biologic therapies and downstream treatment response.

Ocrelizumab concentration and antidrug antibodies are associated with B-cell count in multiple sclerosis

BACKGROUND

The majority of patients with multiple sclerosis on ocrelizumab have B-cell depletion after standard interval dosing of 26 weeks. With B-cell-guided dosing patients receive their next dose when B-cell repopulation occurs. Prediction of B-cell repopulation using ocrelizumab concentrations could aid in personalising treatment regimes. The objectives of this study were to evaluate the association between ocrelizumab drug concentration, antidrug antibodies (ADAs) and CD19 B-cell count, and to define a cut-off ocrelizumab concentration for start of B-cell repopulation (defined by ≥10 CD19+ B cells/µL).

METHODS

In this investigator-initiated prospective study, blood samples at various time points during ocrelizumab treatment were collected from a biobank. Serum ocrelizumab concentrations and ADAs were measured with two different assays developed for this study. Data were analysed using linear mixed effect models. An receiver operating characteristic (ROC) curve was used to determine a cut-off ocrelizumab concentration for start of B-cell repopulation (defined by ≥10 cells/µL).

RESULTS

A total of 452 blood samples from 72 patients were analysed. Ocrelizumab concentrations were detectable up until 53.3 weeks after last infusion and ranged between <0.0025 and 204 µg/mL after 1-67 weeks. Ocrelizumab concentration was negatively associated with B-cell count, with body mass index identified as effect modifier. We found a cut-off value of 0.06 µg/mL for start of B-cell repopulation of ≥10 cells/µL. Ocrelizumab ADAs were detectable in four patients (5.7%) with corresponding low ocrelizumab concentrations and start of B-cell repopulation.

CONCLUSIONS

Serum ocrelizumab concentration was strongly associated with B-cell count. Measurement of ocrelizumab drug concentrations and ADAs could play an important role to further personalise treatment and predict the start of B-cell repopulation.

Therapeutic Drug Monitoring in Practice for Inflammatory Bowel Disease

PURPOSE OF REVIEW

To outline the development, rationale, and practical use of therapeutic drug monitoring in patients with inflammatory bowel disease.

RECENT FINDINGS

Therapeutic drug monitoring is traditionally discussed in terms of a proactive or reactive approach. However, these terms are not always consistently defined and can be confusing when translating research to clinical practice. Personalized approaches incorporating clinical context and precision medicine are emerging. Personalized therapeutic drug monitoring combines a structured and proactive strategy for monitoring biologic concentrations as well as identification of antidrug antibody development or subtherapeutic dosing in the setting of loss of response. Optimizing biologic therapy can improve outcomes and avoid loss of response. Why, when, and how we measure drug troughs and anti-drug antibodies is a moving target, though what is known is that the appropriate and evidence-based use of this practice prevents adverse events and improves outcomes in patients with inflammatory bowel disease.

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.

A Systematic Review on the interest of Drug Tolerant assay in the monitoring of Inflammatory Bowel Disease

Many patients with inflammatory bowel disease (IBD) are treated with anti-tumor necrosis factor (TNF) therapies, of which infliximab (IFX) is most commonly used. Loss of response (LOR) to anti-TNF therapy due to immunogenic failure accounts for 20% of subsequent medical intervention and is defined, using a drug sensitive assay, as low or undetectable concentration of drug with high titers of anti-drug antibodies (ADAb). We performed a systematic review to investigate the use of a drug tolerant assay during both induction and maintenance to monitor patients treated with anti-TNFs. After the search on PubMed, 90 publications were reviewed. Most ADAb detection methods are drug sensitive, cannot detect ADAb in the presence of drug, and therefore cannot be used close to drug administration, when the drug concentration is too high. To overcome this major limitation, several drug-tolerant techniques have been developed and will be discussed in this review. Using drug-tolerant assays ADAb against infliximab (IFX) or adalimumab (ADM) can be detected during induction and predict primary non-response or LOR. Drug sensitive assays do not allow detection of ADAb during the induction phase as IFX or ADM concentration is typically high.

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.

A Practical Guide to Therapeutic Drug Monitoring of Biologic Medications for Inflammatory Bowel Disease

Therapeutic drug monitoring (TDM) is a useful strategy to optimize biologic medications for inflammatory bowel disease not responsive to standard dosing regimens. TDM is cost effective for anti-tumor necrosis factor agents in the setting of loss of response (reactive TDM). Optimizing drug dosing when patients are in remission (proactive TDM) may be beneficial in certain circumstances. However, frequently the serum drug concentration in isolation becomes the focus TDM. Additionally, the lines of reactive and proactive TDM can quickly blur in many common clinical settings. Physicians employing a TDM based strategy need to place the drug concentration in context with the inflammatory status of the patient, the underlying pharmacokinetics and pharmacodynamics of the drug, the risk of immunogenicity, and the therapeutic goals for the patient. Physicians should understand the limits of TDM and feel comfortable making therapeutic decisions with imperfect information. The goal of this narrative review is to provide a framework of questions that physicians can use to employ TDM effectively in practice.

Secondary failure: immune responses to approved protein therapeutics

Recombinant therapeutic proteins are a broad class of biological products used to replace dysfunctional human proteins in individuals with genetic defects (e.g., factor VIII for hemophilia) or, in the case of monoclonal antibodies, bind to disease targets involved in cancers, autoimmune disorders, or other conditions. Unfortunately, immunogenicity (immune response to the drug) remains a key impediment, potentially affecting the safety and efficacy of these therapeutics. Immunogenicity risk is routinely evaluated during the licensure of therapeutic proteins. However, despite eliciting anti-drug immune responses in at least some patients, most protein drugs are nevertheless licensed as they address unmet medical needs. The pre-licensure immunogenicity assessments of therapeutic proteins are the subject of numerous reviews and white papers. However, observation and clinical management of the immunogenicity of approved therapeutic proteins face additional challenges. We survey the immunogenicity of approved therapeutic proteins, discuss the clinical management of immunogenicity, and identify the challenges to establishing clinically relevant immunogenicity assays for use in routine clinical practice.

Therapeutic drug monitoring guides the management of patients with chronic non-infectious uveitis treated with adalimumab: a retrospective study

AIM

To assess the relevance of therapeutic drug monitoring (TDM) of adalimumab (ADA) treatment for the control of intraocular inflammation and treatment adjustment in chronic non-infectious uveitis (CNIU).

METHODS

Retrospective study of CNIU patients treated with ADA and for whom at least one dosage of serum ADA level and an antibodies against ADA (AAA) serology were performed, between June 2003 and July 2019.

RESULTS

A total of 44 ADA-treated patients benefited from a TDM. A total of 48/79 (61%) TDM were performed in responders, 11/79 (14%) in primary non-responders, and 20/79 (25%) in secondary non-responders. Responders had significantly higher ADA levels than non-responders (p=0.0004). AAA were detectable in six patients, they were primary non-responders (n=2), secondary non-responders (n=3) or responders (n=1). In the five non-responders and immunised patients, ADA was switched (to golimumab or methotrexate). Among non-responders, TDM led to an increased frequency of injections 12/31 (38%), increased dose 1/31 (3%) and switch of treatment 10/31 (32%) (one missing data). No modification of biotherapy was performed 7/31 (22%) and only local or oral corticotherapy was adjusted. In 24/31 cases of therapeutic adjustment in non-responders, an improvement was observed in 87% of cases. Among responders for whom the ADA level was above the efficacy threshold, the frequency of injections was decreased for 15/31 (48.4%) cases and no relapse was observed in 12/15 (80%) cases.

CONCLUSION

TDM of ADA treatment proved relevant to provide CNIU patients with a personalised and optimised treatment course (in terms of frequency and type of drug).

Systematic Review and Principal Components Analysis of the Immunogenicity of Adalimumab

BACKGROUND

The reported immunogenicity rates of adalimumab differ significantly between studies because of a wide variety of factors related to the disease, patients, study design, and products.

OBJECTIVE

The objective of this study was to characterize this variability and identify the major factors that contribute to these fluctuations.

METHODS

A systematic literature review was conducted using the MEDLINE, Clinicaltrials.gov, and Cochrane Library databases. Studies that reported the immunogenicity rates of adalimumab were selected, and data pertaining to publication details, study characteristics, characteristics of the cohort at baseline, and immunogenicity were extracted. Records were sorted according to the immunogenicity assay type, and mean immunogenicity values for each assay type were calculated. Normalised immunogenicity was calculated for each report by subtracting the appropriate mean immunogenicity value. Collected data were subjected to statistical analysis, namely analysis of variance (ANOVA) and principal component analysis, to unveil immunogenicity rate patterns across studies from a multivariate perspective.

RESULTS

In total, 130 publications were identified, from which 165 data records were extracted and included in the analysis. The immunogenicity rates of adalimumab averaged 24.9% across studies and varied significantly over time, ranging between 0 and 87%. An increase across time in the reported immunogenicity rates was detected, and the assay used to detect anti-adalimumab antibodies was a significant (but not exclusive) contributor to this trend. Furthermore, the principal components analysis revealed that the type of study and the exposure time were associated with the assay-normalised immunogenicity rates of adalimumab. Nonetheless, neither these nor the remaining factors included in this analysis seem to contribute to the temporal increase in reported immunogenicity rates.

CONCLUSIONS

Future studies that evaluate the patient-, product-, and disease-related factors behind the immunogenicity of adalimumab are required because the evidence published so far does not completely explain the temporal increase in immunogenicity rates detected in this analysis.

Comparison of a new rapid method for determination of serum anti-adalimumab and anti-infliximab antibodies with two established ELISA kits

BACKGROUND

Adalimumab (ADL), infliximab (IFX) and their biosimilars are widely used biological drugs. Some patients, however, generate neutralizing antibodies that hamper the effectiveness of these drugs. Evidence shows therapeutic drug monitoring of serum levels ADL/IFX and anti-drug antibodies (ADA) is useful to improve treatment effectiveness. We evaluated a new rapid quantitative method, Quantum Blue (QB), for determining serum anti-ADL and anti-IFX antibodies (Research Use Only labelling) by comparing it with two established ELISA kits, Promonitor (PM) and Lisa-Tracker (LT).

METHODS

Eighty samples (40 for each drug type) were analysed. Percentage of agreement and kappa statistic were used to compare positive/negative ADA results. Clinical implications for drug treatment in the patients with discordant results were evaluated. The Chi-square test was used to analyze differences for ADA detection in patients with disease flare and without concomitant immunosuppressant treatment.

RESULTS

Agreement exceeded 80 % among anti-ADL methods. Although LT ELISA showed a lower capacity in detecting anti-ADL antibodies, discrepancies were found for levels close to the cut-off concentration, thus having minimal impact on clinical decisions. Conversely, QB anti-IFX displayed low agreement with PM and LT ELISA kits (67.5 % and 50 %, respectively), and was unable to detect high levels of antibodies, therefore having major clinical implications. Agreement between PM and LT ELISA anti-IFX kits was 82.5 % with all discordant results being undetected for PM and slightly positive for LT.

CONCLUSION

QB anti-ADL shows similar performance to ELISA kits while QB anti-IFX needs further improvements to achieve reliable antibody detection.

Immunogenicity of Biologic and Biosimilar Therapies for Psoriasis and Impact of Novel Immunoassays for Immunogenicity Detection

Anti-drug antibodies (ADAs) may develop against originator biologic and biosimilar therapies used for the treatment of psoriasis and may be the cause of initial therapeutic non-response or diminished therapeutic response over time. Comparing immunogenicity between therapeutic agents is challenging owing to the variation in assays used for detection, among other reasons. Using the results of a PubMed search for psoriasis clinical trials disclosing the rates of ADAs for originator biologic and biosimilar therapies approved for the treatment of psoriasis within the last 5 years, this review discusses the rates and potential clinical impact of ADA formation in patients with psoriasis managed with originator biologic and biosimilar therapies, along with novel methods of ADA testing. Anti-drug antibodies are detectable in all biologic and biosimilar therapies approved for the treatment of psoriasis in the last 5 years, and the effect of ADAs on clinical response varies by agent. Novel immunoassays used for the detection of ADAs may have increased sensitivity compared with traditional assays, although the increased rate of detection may not correlate with decreased clinical response and the decision to test for the presence of ADAs may vary from patient to patient. Though ADA formation seems ubiquitous with the use of biologic agents for the treatment of psoriasis, the increased rates of ADAs detected by novel immunoassays may not necessarily correlate with decreased treatment efficacy.

Immunogenicity of biologic agents in rheumatology

Biologic agents have become a core component of therapeutic strategies for many inflammatory rheumatic diseases. However, perhaps reflecting the specificity and generally high affinity of biologic agents, these therapeutics have been used by rheumatologists with less consideration of their pharmacokinetics than that of conventional synthetic DMARDs. Immunogenicity was recognized as a potential limitation to the use of biologic agents at an early stage in their development, although regulatory guidance was relatively limited and assays to measure immunogenicity were less sophisticated than today. The advent of biosimilars has sparked a renewed interest in immunogenicity that has resulted in the development of increasingly sensitive assays, an enhanced appreciation of the pharmacokinetic consequences of immunogenicity and the development of comprehensive and specific guidance from regulatory authorities. As a result, rheumatologists have a greatly improved understanding of the field in general, including the factors responsible for immunogenicity, its potential clinical consequences and the implications for everyday treatment. In some specialties, immunogenicity testing is becoming a part of routine clinical management, but definitive evidence of its cost-effectiveness in rheumatology is awaited.

Immunogenicity of biologic therapies in psoriasis: Myths, facts and a suggested approach

With biologic drugs dominating the therapeutic space for severe immune-mediated inflammatory disease, it is critical for clinicians to be familiar with the concept of drug immunogenicity, with the potential for our patients to develop antidrug antibodies (ADA) of clinical relevance. Whilst there are clear differences between different therapeutic biologics in terms of reported ADA rates, there is no accepted dermatology guideline or grouping of drugs by risk of clinically relevant ADA, nor a consensus on approach to ADA management. This is partly because making valid comparisons of immunogenicity across drugs is fundamentally flawed: the differing types of ADA assay, trial design and included patient population - as well as the molecular structure of the biologic molecules themselves - are all highly influential on reported ADA prevalence and impact on clinical response. Therefore, the first part of this article aims to give an overview of ADA that also clarifies common misconceptions on the subject, whilst the second part of this article outlines Phase III immunogenicity data on commonly used biologics for psoriasis, the most common dermatological indication. Based on this, and acknowledging current limitations in available evidence, we propose a working categorization of biologics together with a broad approach to management: Group 1 - biologics with higher risk of clinically relevant ADA; Group 2 - biologics with lower risk of clinically relevant ADA; and Group 3 - biologics with no established risk of clinically relevant ADA. However, these groupings represent a working concept only; more research is required, using comparable ADA assays and consistent reporting of related outcomes. Finally, there is an urgent need for better characterization of individuals at particular risk of developing ADA to inform future clinical decision-making.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Biomarkers of disease activity and other factors as predictors of adalimumab pharmacokinetics in inflammatory bowel disease

Inflammatory bowel disease (IBD) is commonly treated with adalimumab. The main objective of the study was to develop a population pharmacokinetic model of adalimumab in IBD patients evaluating the potential biomarkers of disease activity and other factors and its implications in adalimumab dosing. A prospective observational study was performed in adult patients diagnosed with Crohn's disease and ulcerative colitis treated with adalimumab and following a proactive therapeutic drug monitoring of serum concentrations. Adalimumab serum concentrations (ASC) were quantified mainly prior the administration using an enzyme-linked immunosorbent assay (ELISA). A population pharmacokinetic model was developed based on 303 ASC data of 104 IBD patients using non-linear mixed effect modelling approach. Sixty-five ASC from 20 additional patients were randomly selected as an external validation group. A one-compartment model with first order absorption and elimination best describe the ASC time course. Body mass index (BMI), faecal calprotectin (FCP), unexplained decline in ASC and the specific administration pen device exhibited significant influence on apparent clearance (p-value < 0.001). FCP was the inflammatory activity biomarker showing the most relevant impact on adalimumab exposure, higher than C-reactive protein and albumin, and may be useful for adalimumab dosing adjustment. The population-based pharmacokinetic model developed adequately characterized adalimumab exposure in IBD patients. The unexplained decline in ASC, FCP, BMI and the specific administration pen device were identified as meaningful variables significantly influencing adalimumab pharmacokinetics.

Refractory Sarcoidosis: A Review

Sarcoidosis is a multi-system disease of unknown etiology characterized by granuloma formation in various organs (especially lung and mediastinohilar lymph nodes). In more than half of patients, the disease resolves spontaneously. When indicated, it usually responds to corticosteroids, the first-line treatment, but some patients may not respond or tolerate them. An absence of treatment response is rare and urges for verifying the absence of a diagnosis error, the good adherence of the treatment, the presence of active lesions susceptible to respond since fibrotic lesions are irreversible. That is when second-line treatments, immunosuppressants (methotrexate, leflunomide, azathioprine, mycophenolate mofetil, hydroxychloroquine), should be considered. Methotrexate is the only first-line immunosuppressant validated by a randomized controlled trial. Refractory sarcoidosis is not yet a well-defined condition, but it remains a real challenge for the physicians. Herein, we considered refractory sarcoidosis as a disease in which second-line treatments are not sufficient to achieve satisfying disease control or satisfying corticosteroids tapering. Tumor necrosis alpha inhibitors, third-line treatments, have been validated through randomized controlled trials. There are currently no guidelines or recommendations regarding refractory sarcoidosis. Moreover, criteria defining non-response to treatment need to be clearly specified. The delay to achieve response to organ involvement and drugs also should be defined. In the past ten years, the efficacy of several immunosuppressants beforehand used in other autoimmune or inflammatory diseases was reported in refractory cases series. Among them, anti-CD20 antibodies (rituximab), repository corticotrophin injection, and anti-JAK therapy anti-interleukin-6 receptor monoclonal antibody (tocilizumab) were the main reported. Unfortunately, no clinical trial is available to validate their use in the case of sarcoidosis. Currently, other immunosuppressants such as JAK inhibitors are on trial to assess their efficacy in sarcoidosis. In this review, we propose to summarize the state of the art regarding the use of immunosuppressants and their management in the case of refractory or multidrug-resistant sarcoidosis.

What Is the Clinical Relevance of TNF Inhibitor Immunogenicity in the Management of Patients With Rheumatoid Arthritis?

Tumor necrosis factor-α inhibitors (TNFis) have revolutionized the management of rheumatoid arthritis (RA), however despite considerable progress, only a small proportion of patients maintain long-term clinical response. Selection of, and switching between, biologics is mainly empirical, experiential, and not evidence-based. Most biopharmaceutical proteins (BP) can induce an immune response against the foreign protein component. Immunogenicity and the development of anti-drug antibodies (ADAs) is considered one of the main reasons for loss of therapeutic efficacy (secondary failure). ADAs may neutralize and/or promote clearance of circulating BP with resultant low serum drug levels, loss of clinical response, poor drug survival and adverse events, such as infusion reactions. ADA identification is technically difficult and not standardized, making interpretation of immunogenicity data from published clinical studies challenging. Trough TNFi drug levels correlate with clinical outcomes, exhibiting a "concentration-response" relationship. Measurement of ADA and drug levels may improve patient care and improve cost-effectiveness of BP use. However, in the absence of clinically-validated, reliable assays and consensus guidelines, therapeutic drug monitoring (TDM) and immunogenicity testing have not been widely adopted in routine clinical practice in Rheumatology. Here we discuss the utility and relevance of TDM and immunogenicity testing of TNFis in RA (focusing on the most widely used TNFis globally, with the most available data, i.e., infliximab, adalimumab, and etanercept), the limitations of currently available assays and potential future immunopharmacological strategies to personalize disease management.

Molecular Landscape of Anti-Drug Antibodies Reveals the Mechanism of the Immune Response Following Treatment With TNFα Antagonists

Drugs formulated from monoclonal antibodies (mAbs) are clinically effective in various diseases. Repeated administration of mAbs, however, elicits an immune response in the form of anti-drug-antibodies (ADA), thereby reducing the drug's efficacy. Notwithstanding their importance, the molecular landscape of ADA and the mechanisms involved in their formation are not fully understood. Using a newly developed quantitative bio-immunoassay, we found that ADA concentrations specific to TNFα antagonists can exceed extreme concentrations of 1 mg/ml with a wide range of neutralization capacity. Our data further suggest a preferential use of the λ light chain in a subset of neutralizing ADA. Moreover, we show that administration of TNFα antagonists result in a vaccine-like response whereby ADA formation is governed by the extrafollicular T cell-independent immune response. Our bio-immunoassay coupled with insights on the nature of the immune response can be leveraged to improve mAb immunogenicity assessment and facilitate improvement in therapeutic intervention strategies.

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.

Routinely utilized in-house assays for infliximab, adalimumab and their anti-drug antibody levels

By monitoring serum concentrations of infliximab (IFX) and adalimumab (ADL) and levels of their antibodies in patients with inflammatory diseases, clinicians can adjust dose and increase safety and effectiveness of treatment. The aim was to develop and validate in-house enzyme-linked immunosorbent assays (ELISAs) for IFX and ADL, together with anti-IFX and anti-ADL ELISAs for routine detection and further analysis with acid dissociation of immune complexes. Furthermore, the objectives were to compare in-house assays with commercial ELISAs and reporter gene assays (RGAs) and to determine cross-reactivity between original Remicade®/Remsima™ and their antibodies. In-house ELISAs were validated (imprecision, accuracy among other criteria) and compared with commercial apDia ELISAs and RGAs. Correlation coefficients, intraclass correlation coefficients, agreement, and bias were calculated. All in-house ELISAs gave precise and repeatable results. The immune complexes between IFX and anti-IFX were found in 3% of samples, while complexes between ADL and anti-ADL were found in 14% of samples. Significant correlations were found between in-house and apDia ELISAs and RGA for IFX, ADL, anti-IFX, and anti-ADL results. Remicade®, Remsima™, and their antibodies could be accurately measured with either apDia or in-house IFX and anti-IFX ELISAs. Accurate and precise in-house ELISAs, highly comparable with commercial ELISAs and RGAs, were developed and validated for routine analysis of samples of patients treated with IFX (Remicade® or Remsima™) or ADL providing substantial cost benefit. Complex dissociation identified samples with anti-IFX-IFX (3%) and anti-ADL-ADL (14%) complexes indicating the benefit of adding acid dissociation to therapeutic drug monitoring of IFX and ADL.

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.

Serum drug concentrations to optimize switching from adalimumab to etanercept in rheumatoid arthritis

Objectives: Inadequate response to adalimumab can be caused by insufficient blockade of the target tumour necrosis factor (TNF) at low serum concentrations. In such cases, patients may respond to another TNF inhibitor. We investigated whether the serum adalimumab concentration is related to the efficacy of a second TNF inhibitor, etanercept, in rheumatoid arthritis (RA). Methods: Patients with RA starting etanercept treatment were prospectively observed in the Reade Rheumatology Registry. In patients previously on adalimumab, serum concentrations were determined before treatment discontinuation. According to this concentration, three subgroups were formed: < 0.5 μg/mL, 0.5-5.0 μg/mL, and ≥ 5.0 μg/mL. The European League Against Rheumatism (EULAR) good/moderate response rate after 52 weeks of etanercept was compared between the switcher subgroups and biologic-naive patients. Results: In total, 449 consecutive patients were included, of whom 69 switched from adalimumab (15%) and 380 were biologic naive (85%). EULAR good or moderate response was achieved by 74% of the biologic-naive patients and by 72%, 50%, and 52% of switchers with adalimumab concentration < 0.5 μg/mL, 0.5-5.0 μg/mL, and ≥ 5.0 μg/mL, respectively (p = 0.15). Patients with an adalimumab concentration ≥ 0.5 μg/mL were significantly less likely to achieve EULAR good/moderate response on etanercept compared to biologic-naive patients, whereas patients with a concentration < 0.5 μg/mL did not significantly differ from patients starting etanercept without prior biologic treatment. Conclusion: RA patients with an inadequate response to adalimumab, in the presence of sufficient drug concentrations, benefit less from switching to another TNF inhibitor, etanercept.

Association between concomitant csDMARDs and clinical response to TNF inhibitors in overweight patients with axial spondyloarthritis

Background

The aim of our study was to investigate the influence of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and body mass index (BMI) on circulating drug levels and clinical response to tumour necrosis factor inhibitor (TNFi) therapy in axial spondyloarthritis (axSpA) patients.

Methods

Prospective observational study during 1 year with 2 cohorts (Madrid and Amsterdam) including 180 axSpA patients treated with standard doses of infliximab or adalimumab. Patients were stratified by BMI, being 78 (43%) normal weight (18.5–24.9 kg/m²) and 102 (57%) overweight/obese (≥ 25.0 kg/m²). After the first year of treatment, TNFi trough levels were measured by capture ELISA. Clinical response to TNFi was defined as ∆BASDAI ≥ 2 and clinical remission as BASDAI < 2 and CRP ≤ 5 mg/L. Logistic regression models were employed to analyse the association between concomitant csDMARDs and BMI with drug levels and clinical response.

Results

Seventy-nine patients (44%) received concomitant csDMARDs. The administration of concomitant csDMARDs (OR 3.82; 95% CI 1.06–13.84) and being normal weight (OR 18.38; 95% CI 2.24–150.63) were independently associated with serum TNFi drug persistence. Additionally, the use of concomitant csDMARDs contributed positively to achieve clinical response (OR 7.86; 95% CI 2.39–25.78) and remission (OR 4.84; 95% CI 1.09–21.36) in overweight/obese patients, but no association was found for normal-weight patients (OR 1.10; 0.33–3.58).

Conclusions

The use of concomitant csDMARDs with TNFi may increase the probability of achieving clinical response in overweight/obese axSpA patients. Further research studies including larger cohorts of patients need to be done to confirm it.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1849-3) contains supplementary material, which is available to authorized users.

The effect of methotrexate versus other disease-modifying anti-rheumatic drugs on serum drug levels and clinical response in patients with rheumatoid arthritis treated with tumor necrosis factor inhibitors

To investigate the effect of concomitant conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) with adalimumab or infliximab on maintaining serum drug and clinical outcomes after the first year of treatment in patients with rheumatoid arthritis (RA). Second, to assess the influence of methotrexate (MTX) dose on these outcomes. Ninety-two patients with RA starting infliximab (n = 67) or adalimumab (n = 25) tumor necrosis factor inhibitor (TNFi) with available drug levels and clinical improvement assessment (European League Against Rheumatism [EULAR] response) after 12 months were included. Patients were grouped according to concomitant csDMARD use: (i) TNFi monotherapy; (ii) TNFi+MTX; (iii) TNFi with csDMARDs other than MTX (TNFi+OD). Patients receiving MTX were also classified by dose as < 15 mg/week (TNFi+MTX<15) and ≥ 15 mg/week (TNFi+MTX≥15). Logistic regression analyses were employed. More TNFi+MTX patients had circulating serum TNFi at 12 months (71% TNFi+MTX vs. 20% TNFi+OD vs. 9% TNFi monotherapy). Of these, the probability of maintaining serum TNFi levels was twice (OR 2.3; p = 0.06) than that of patients without MTX. However, statistically significant results were observed only for the highest MTX dose (OR 4.9; p = 0.02). Most patients achieving good EULAR response were treated with TNFi+MTX (81%). The probability of achieving this response was three times higher in patients within the TNFi+MTX group (OR 3.4; p = 0.03); however, no differences were found with regard to MTX dose. The persistence of serum TNFi and the probability of achieving clinical response are influenced by MTX but not by OD in patients with RA treated with infliximab or adalimumab.

Restricted immune activation and internalisation of anti-idiotype complexes between drug and antidrug antibodies

Objectives

Therapeutic antibodies can provoke an antidrug antibody (ADA) response, which can form soluble immune complexes with the drug in potentially high amounts. Nevertheless, ADA-associated adverse events are usually rare, although with notable exceptions including infliximab. The immune activating effects and the eventual fate of these ‘anti-idiotype’ complexes are poorly studied, hampering assessment of ADA-associated risk of adverse events. We investigated the in vitro formation and biological activities of ADA-drug anti-idiotype immune complexes using patient-derived monoclonal anti-infliximab antibodies.

Methods

Size distribution and conformation of ADA-drug complexes were characterised by size-exclusion chromatography and electron microscopy. Internalisation of and immune activation by complexes of defined size was visualised with flow imaging, whole blood cell assay and C4b/c ELISA.

Results

Size and conformation of immune complexes depended on the concentrations and ratio of drug and ADA; large complexes (>6 IgGs) formed only with high ADA titres. Macrophages efficiently internalised tetrameric and bigger complexes in vitro, but not dimers. Corroborating these results, ex vivo analysis of patient sera demonstrated only dimeric complexes in circulation.

No activation of immune cells by anti-idiotype complexes was observed, and only very large complexes activated complement. Unlike Fc-linked hexamers, anti-idiotype hexamers did not activate complement, demonstrating that besides size, conformation governs immune complex potential for triggering effector functions.

Conclusions

Anti-idiotype ADA-drug complexes generally have restricted immune activation capacity. Large, irregularly shaped complexes only form at high concentrations of both drug and ADA, as may be achieved during intravenous infusion of infliximab, explaining the rarity of serious ADA-associated adverse events.

Immunogenicity testing of therapeutic antibodies in ocular fluids after intravitreal injection

Aim: High drug concentrations in ocular fluids after intravitreal administration preclude the use of drug-sensitive immunoassays. A drug-tolerant immunoassay is therefore desirable for immunogenicity testing in ophthalmology. Experimental: Immune complex (IC) antidrug antibody (ADA) assays were established for two species. The assays were compared with the bridging assay in ocular and plasma samples from two preclinical studies. Results: The IC assays showed high drug tolerance, which enabled a reliable ADA detection in ocular fluids after intravitreal administration. The IC assays were superior to the bridging assay in the analysis of ocular fluids with high drug concentrations. Conclusion: The IC assay allows a reliable ADA detection in matrices with high drug concentrations, such as ocular fluids.

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.

Immunoassays for Measuring Serum Concentrations of Monoclonal Antibodies and Anti-biopharmaceutical Antibodies in Patients

Monoclonal antibodies (mAbs) may be used as biopharmaceuticals to treat various diseases, ranging from oncology to inflammatory and cardiovascular affections. Trustworthy analytical methods are necessary to study their pharmacokinetics, both during their development and in post-marketing studies. Because biopharmaceuticals are macromolecules, ligand-binding assays (both immunoassays and bioassays) are methods of choice to measure their concentrations. Immunoassays are based on the capture of biopharmaceuticals by their target, which may be a circulating or membrane antigen or by an antibody recognizing their structure. Bioassays measure the activity of the biopharmaceutical in a specific in vitro test. A number of techniques have been reported, but their limits of detection and quantification vary widely. Anti-drug antibodies (ADA) against biopharmaceuticals are often formed and sometimes interfere with clinical efficacy. Accurate and reliable detection of ADA is therefore necessary. Binding of ADA is dependent on affinity and avidity, which makes quantification challenging. In this review, we discuss the benefits and limitations of each method to determine mAb levels and carefully compare ADA assays.

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.

Immunogenicity of biologics in inflammatory bowel disease

Crohn's disease and ulcerative colitis are chronic inflammatory disorders of the gastrointestinal tract. Treatment options include biologic therapies; however, a proportion of patients lose response to biologics, partly due to the formation of anti-drug antibodies (ADAbs). Concomitant immunosuppressive agents reduce the development of ADAbs. This review article aims to assess the immunogenicity of biologic therapies and their clinical implications. A comprehensive literature search was conducted for articles published January 2009 to August 2015 reporting immunogenicity to adalimumab (ADM), certolizumab pegol (CZP), golimumab, infliximab (IFX), ustekinumab, and vedolizumab in inflammatory bowel disease (IBD). Eligible articles were reviewed and quality assessed by independent reviewers. Overall, 122 publications reporting 114 studies were assessed. ADAbs were reported for all agents, but the percentage of patients developing ADAbs was extremely variable, with the highest (65.3%) being for IFX administration to patients with IBD. ADAb presence was frequently associated with a reduction in primary efficacy and a loss of response, and, for IFX, an increase in adverse events (AEs). Lower serum levels of ADM, CZP and IFX were seen in ADAbs-positive rather than ADAbs-negative patients; pharmacokinetic data were unavailable for other therapies. Little information was available regarding the timing of ADAb development; studies reported their detection from as early as 10-14 days up to months after treatment initiation. Biologic therapies carry an intrinsic risk of immunogenicity, although reported rates of ADAbs vary considerably. The clinical implications of immunogenicity are a concern for effective treatment; further research, particularly into the more recently approved biologics, is required.

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.

Dried blood spots from finger prick facilitate therapeutic drug monitoring of adalimumab and anti-adalimumab in patients with inflammatory diseases

AIMS

Development of a self-sampling method for therapeutic drug monitoring (TDM) of biologicals will enhance TDM implementation in routine care and pharmacokinetic knowledge. The aim of this study was to compare adalimumab and anti-adalimumab antibody (ADA) concentration measurements in dried blood spots (DBS) obtained from finger prick with measurements in serum obtained via venepuncture, from patients with rheumatic inflammatory diseases.

METHODS

In this cross-sectional study, 161 consecutive patients were included. For clinical validation, DBS from finger prick and serum from venepuncture were collected simultaneously and adalimumab and ADA concentration were assessed by ELISA and antigen binding test (ABT), respectively. To convert DBS eluate results to values which can be compared to serum concentrations, five different methods were investigated, using a marker protein or a volumetric approach.

RESULTS

Adalimumab and ADA concentrations obtained from the finger prick/DBS method correlated well with serum results from the same patient (correlation coefficient > 0.87). Interestingly, antibody concentrations (either adalimumab, ADA or total immunoglobulin G) in DBS from finger prick, but not albumin, were systematically lower compared to serum. Spike experiments demonstrated a quantitative recovery for all tested proteins in DBS, suggesting a slightly different protein composition of blood collected via finger prick vs. venepuncture. We established a correction factor to relate finger prick/DBS values with serum values (approximately 1.2).

CONCLUSIONS

We show here for the first time that adalimumab and ADA serum concentrations can be satisfactorily estimated by measuring concentrations in DBS eluates, collected by finger prick. This method offers great opportunity to simplify TDM of adalimumab.

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.

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.

Clinical impact of immunomonitoring in the treatment of inflammatory bowel disease

Despite improvement in outcomes, loss of response (LOR) to tumor necrosis factor-alpha (TNFα) therapies is a big concern in the management of inflammatory bowel disease. LOR is associated with flares of disease, increased hospitalisation rates, need for surgical interventions, and decline in quality of life. LOR may be multifactorial, but immunogenicity makes a significant contribution. Traditionally doses of anti-TNFα have been adjusted based on clinical response, using a standard approach. Immunomonitoring involves the measurement of anti-TNFα trough and antibody levels. It takes into account the underlying pharmacokinetics of anti-TNFα therapies. Expanding on this a treat to target approach may be used, where doses are intensified, or tailored to the individual based on the measurement of anti-TNFα trough and antibody levels. This review looks at the history, evolution, and clinical impact that immunomonitoring is having in the treatment of inflammatory bowel disease. It will focus on the role of immunomonitoring in helping to achieve long lasting deep remission and mucosal healing. It will explore the different options in terms of best measuring trough and antibody levels, explore possible advantages of immunomonitoring, and discuss its role in best optimising response, at induction, during the maintenance phase of treatment, as well as a role in withdrawing or switching therapy.

Standardization of the homogeneous mobility shift assay protocol for evaluation of anti-infliximab antibodies. Application of the method to Crohn's disease patients treated with infliximab

BACKGROUND

The availability of a quantitative method to measure anti-infliximab (IFX) antibodies (ATI) would facilitate the implementation of therapeutic drug monitoring in clinical decision-making. Our aim was to standardize the homogeneous mobility shift assay (HMSA) used in the measure of ATI levels.

METHODS

In this prospective longitudinal multicenter study, 50 IFX-treated Crohn's disease (CD) patients were followed up for 54weeks. During this period 360 human serum samples were analysed. Monomeric ATI levels were measured by a quantitative HMSA-method using an anti-IFX calibrator. IFX trough levels measured by ELISA were correlated with ATI levels.

RESULTS

Using HMSA and a pure anti-idiotypic monoclonal antibody specific for IFX (anti-IFX calibrator), we measured the levels of monomeric ATI generated in Crohn's disease patients treated with IFX. Anti-IFX calibrator allowed to quantify monomeric antibodies against IFX with a low limit of quantification (3nM). The threshold level of ATI in order to classify the immunogenicity of the patients was 10nM. We observed that 24% (12/50) of IFX-treated patients developed ATI (>10nM) during the observation period (54weeks). Serum concentration of ATI higher than 10nM dramatically increased the probability (OR=51.1; 95% CI: 20.4-128.0; p<0.0001) of presenting low levels of IFX (⩽1.5nM) in serum, as observed in some CD patients treated with standard doses of the drug.

CONCLUSIONS

The HMSA-method described here allows an accurate quantification of ATI concentration in international units (IU) and therefore it could be useful in the study of the relationship between ATI concentration, infliximab level and the clinical response to the drug.

Immunogenicity Assessment of Tumor Necrosis Factor Antagonists in the Clinical Laboratory

BACKGROUND

Tumor necrosis factor (TNF) antagonists are increasingly used for the treatment of inflammatory and autoimmune diseases. Immunogenicity of these drugs poses therapeutic challenges such as therapeutic failure and adverse effects in a number of patients. Evaluation of clinical nonresponsiveness includes laboratory testing for drug concentrations and detecting the presence of antidrug antibodies.

CONTENT

This review provides an overview of the immunogenicity of TNF antagonists and testing methodologies currently available for measuring antidrug antibody response, which decreases treatment efficacy and may result in therapeutic failure. This review summarizes methodologies such as binding assays, including ELISA and HPLC-based homogenous mobility shift assay, as well as functional cell-based assays such as reporter gene assay. Furthermore, based on the laboratory findings of testing for antidrug antibody response, as well as serum drug concentrations, an algorithm is provided for interpretation, based on the current available literature and guidelines, which may aid in determining optimal therapy after treatment failure.

SUMMARY

Laboratory testing methodologies for measuring serum concentrations of TNF inhibitors and antidrug antibodies are clinically available. These methods provide an evidence-based, personalized approach for the workup of patients showing treatment failure, which saves time and resources, and contributes to improved patient care.

Detection of anti-drug antibodies using a bridging ELISA compared with radioimmunoassay in adalimumab-treated rheumatoid arthritis patients with random drug levels

Objective. To determine the concordance between RIA and bridging ELISA at detecting anti-drug antibodies (ADAbs) in the context of random adalimumab levels and investigate the additional clinical utility of detecting ADAbs in RA patients who test ADAb positive by RIA and negative by ELISA.

Methods. ADAb levels were determined using RIA and bridging ELISA in 63 adalimumab-treated RA patients (159 samples). Immunogenicity concordance was determined using receiver operating characteristic curves. To determine the additional clinical value provided by a positive RIA in the presence of negative ELISA, association between treatment response (ΔDAS28), adalimumab drug levels and ADAbs was evaluated longitudinally using generalized estimating equation.

Results. Of the 60 RIA⁺ samples (n = 31 patients), 19 (n = 10 patients) were also ELISA⁺, corresponding to 31.7% of samples. Area under the curve for detecting ADAbs using ELISA (compared with RIA) using receiver operating characteristic curves was 0.65 (95% CI: 0.59, 0.71); this increased to 0.91 (95% CI: 0.81, 0.99) if ADAbs were ⩾100 AU/ml using RIA. In RIA⁺/ELISA⁻ patients, adalimumab levels were associated with ΔDAS28 over 12 months [regression coefficient: 0.098 (95% CI: 0.043, 0.15), P < 0.0001] and while ADAbs were significantly associated with drug level, they were not directly associated with ΔDAS28 over 12 months [β coefficient: 0.00083 (95% CI: −0.0038 to 0.0054), P = 0.72].

Conclusion. ADAbs were detected using ELISA more frequently when present in high titres as measured by RIA. In RIA⁺/ELISA⁻ patients, only drug levels were significantly associated with treatment response. Although ADAbs were not independently associated with treatment response, they may be helpful in determining the aetiology of low drug levels.

Serum tocilizumab trough concentration can be used to monitor systemic IL-6 receptor blockade in patients with rheumatoid arthritis: a prospective observational cohort study

OBJECTIVES

To investigate the pharmacokinetics (PK) and dynamics of tocilizumab (TCZ) in daily practice.

METHOD

An observational study of 66 consecutive RA patients treated with TCZ 8 mg/kg once every 4 weeks intravenously, monitored for 24 weeks. Spearman's rank test was used to investigate the correlation between TCZ concentration and C-reactive protein (CRP). Clinical improvement was assessed at week 24 using the Disease Activity Score in 28 joints (DAS28) compared to baseline, and its relationship with TCZ concentration was investigated using linear regression analyses. TCZ trough concentrations and anti-drug antibodies were measured using an enzyme-linked immunosorbent assay (ELISA) and antigen binding test, respectively.

RESULTS

At baseline, 26 patients (39.4%) had a CRP level above 10 mg/L with a median (interquartile range, IQR) of 37.7 (21.9-49.7) mg/L. A TCZ concentration above 1 mg/L was sufficient to normalize CRP levels. Spearman's rank test showed a correlation coefficient of -0.460 (p < 0.0001). The TCZ concentration varied widely, with concentrations < 1 mg/L in 17-31% of patients, depending on the time point of measurement. Anti-TCZ antibodies were detected in one sample. Linear regression analyses showed a coefficient of 0.080 with a 95% confidence interval (CI) of 0.039-0.113 (p < 0.001) for the association between TCZ concentration and ΔDAS28. No confounders were identified.

CONCLUSIONS

The TCZ standard regimen results in a wide variety of serum TCZ trough concentrations; this is mostly due to target binding and to a lesser extent to immunogenicity. The majority of patients obtained TCZ concentrations > 1 mg/L, which is sufficient for CRP normalization. Therefore, dose taper strategies might be possible in a substantial proportion of patients.