Anti-adalimumab antibodies in juvenile idiopathic arthritis: frequent association with loss of response

Prospective study to characterize adalimumab exposure in pediatric patients with rheumatic diseases

BACKGROUND

In pediatric rheumatic diseases (PRD), adalimumab is dosed using fixed weight-based bands irrespective of methotrexate co-treatment, disease activity (DA) or other factors that might influence adalimumab pharmacokinetics (PK). In rheumatoid arthritis (RA) adalimumab exposure between 2-8 mg/L is associated with clinical response. PRD data on adalimumab is scarce. Therefore, this study aimed to analyze adalimumab PK and its variability in PRD treated with/without methotrexate.

METHODS

A two-center prospective study in PRD patients aged 2-18 years treated with adalimumab and methotrexate (GA-M) or adalimumab alone (GA) for ≥ 12 weeks was performed. Adalimumab concentrations were collected 1-9 (maximum concentration; Cmax), and 10-14 days (minimum concentration; Cmin) during ≥ 12 weeks following adalimumab start. Concentrations were analyzed with enzyme-linked immunosorbent assay (lower limit of quantification: 0.5 mg/L). Log-normalized Cmin were compared between GA-M and GA using a standard t-test.

RESULTS

Twenty-eight patients (14 per group), diagnosed with juvenile idiopathic arthritis (71.4%), non-infectious uveitis (25%) or chronic recurrent multifocal osteomyelitis (3.6%) completed the study. GA-M included more females (71.4%; GA 35.7%, p = 0.13). At first study visit, children in GA-M had a slightly longer exposure to adalimumab (17.8 months [IQR 9.6, 21.6]) compared to GA (15.8 months [IQR 8.5, 30.8], p = 0.8). Adalimumab dosing was similar between both groups (median dose 40 mg every 14 days) and observed DA was low. Children in GA-M had a 27% higher median overall exposure compared to GA, although median Cmin adalimumab values were statistically not different (p = 0.3). Cmin values ≥ 8 mg/L (upper limit RA) were more frequently observed in GA-M versus GA (79% versus 64%). Overall, a wide range of Cmin values was observed in PRD (0.5 to 26 mg/L).

CONCLUSION

This study revealed a high heterogeneity in adalimumab exposure in PRD. Adalimumab exposure tended to be higher with methotrexate co-treatment compared to adalimumab monotherapy although differences were not statistically significant. Most children showed adalimumab exposure exceeding those reported for RA with clinical response, particularly with methotrexate co-treatment. This highlights the need of further investigations to establish model-based personalized treatment strategies in PRD to avoid under- and overexposure.

TRIAL REGISTRATION

NCT04042792 , registered 02.08.2019.

Perspectives of Therapeutic Drug Monitoring of Biological Agents in Non-Infectious Uveitis Treatment: A Review

Biological drugs, especially those targeting anti-tumour necrosis factor α (TNFα) molecule, have revolutionized the treatment of patients with non-infectious uveitis (NIU), a sight-threatening condition characterized by ocular inflammation that can lead to severe vision threatening and blindness. Adalimumab (ADA) and infliximab (IFX), the most widely used anti-TNFα drugs, have led to greater clinical benefits, but a significant fraction of patients with NIU do not respond to these drugs. The therapeutic outcome is closely related to systemic drug levels, which are influenced by several factors such as immunogenicity, concomitant treatment with immunomodulators, and genetic factors. Therapeutic drug monitoring (TDM) of drug and anti-drug antibody (ADAbs) levels is emerging as a resource to optimise biologic therapy by personalising treatment to bring and maintain drug concentration within the therapeutic range, especially in those patients where a clinical response is less than expected. Furthermore, some studies have described different genetic polymorphisms that may act as predictors of response to treatment with anti-TNFα agents in immune-mediated diseases and could be useful in personalising biologic treatment selection. This review is a compilation of the published evidence in NIU and in other immune-mediated diseases that support the usefulness of TDM and pharmacogenetics as a tool to guide clinicians’ treatment decisions leading to better clinical outcomes. In addition, findings from preclinical and clinical studies, assessing the safety and efficacy of intravitreal administration of anti-TNFα agents in NIU are discussed.

Clinical benefits and potential risks of adalimumab in non-JIA chronic paediatric uveitis

Purpose

To describe the treatment results with adalimumab in chronic paediatric uveitis, not associated with juvenile idiopathic arthritis (JIA).

Methods

Medical records of children with non‐JIA‐uveitis were reviewed retrospectively. Children without an underlying systemic disease were pre‐screened with brain magnetic resonance imaging (MRI) to exclude white matter abnormalities/demyelination.

Results

Twenty‐six patients were pre‐screened with brain MRI, of whom adalimumab was contraindicated in six patients (23%) with non‐anterior uveitis. Forty‐three patients (81 eyes) were included. Disease inactivity was achieved in 91% of the patients after a median of three months (3–33). Best‐corrected visual acuity (BCVA) improved from 0.16 ± 0.55 logarithm of the minimum angle of resolution (logMAR) at baseline to 0.05 ± 0.19 logMAR at 24 months (p = 0.015). The median dosage of systemic corticosteroids was reduced to 0 mg/day at 24 months of follow‐up (versus 10 mg/day at baseline; p < 0.001). Adalimumab was discontinued in thirteen children due to ineffectiveness (n = 8), side effects (n = 1), long‐term inactivity of uveitis (n = 3) or own initiative (n = 1). Relapse of uveitis occurred in 19 (49%) patients, 5 (26%) of them without an identifiable cause.

Conclusion

Adalimumab is effective in the treatment of non‐JIA‐uveitis in paediatric patients by achieving disease inactivity in the majority of the patients, improving BCVA and decreasing the dose of corticosteroids. Adverse events and side effects are limited. Pre‐screening with MRI of the brain is recommended in paediatric patients with intermediate and panuveitis.

The Efficacy and Safety of Adalimumab in Treating Pediatric Noninfectious Chronic Anterior Uveitis With Peripheral Retinal Vascular Leakage: A Pilot Study

Purpose

This study is aimed to assess the efficacy of adalimumab in alleviating peripheral vascular leakage in pediatric chronic anterior uveitis patients, along with its ability to improve best-corrected visual acuity (BCVA) and inflammation parameters, its efficacy in reducing topical glucocorticosteroids (GCs) and systemic immunomodulatory therapy (IMT), and its safety profile.

Methods

A self-controlled study of pediatric chronic anterior uveitis patients who presented with peripheral retinal vascular leakage on ultra-widefield fluorescein fundus angiography and underwent adalimumab treatment was conducted. The primary outcome was the extent of retinal vascular leakage at the 3- and 6-month follow-up visits. Secondary outcomes included BCVA, inflammation parameters (fresh keratic precipitates, anterior chamber cell, and vitreous cell grades), frequency of topical glucocorticosteroid eye drops, IMT load, and adverse effects at the 3- and 6-month follow-up visits.

Results

Twenty patients with a mean age of 9.30 ± 3.26 years old were included. The mean follow-up period was 9.0 ± 3.0 months, with all patients followed up for at least 6 months. At the 3- and 6-month follow-ups, the peripheral vascular leakage score decreased significantly (2.87, 95% CI (2.14, 3.60), p < 0.001 for 3 months, 2.75, 95% CI (1.76, 3.73), p < 0.001 for 6 months). Alongside BCVA (p = 0.013 for 3 months, p = 0.005 for 6 months) was improved significantly, inflammatory parameters represented by fresh keratic precipitates, anterior chamber cell, and vitreous cell grades were improved significantly (p < 0.001, p < 0.001, for all parameters) and topical GC usage was significantly reduced (p < 0.001, p < 0.001) at 3 and 6 months. There was also a statistically significant reduction in systemic IMT load at 6 months (p < 0.001). Adverse events in the observation period included local redness around the injection site and mild upper respiratory symptoms.

Conclusion

Adalimumab could effectively alleviate peripheral vascular leakage in pediatric patients with chronic anterior uveitis. It could also be helpful in improving BCVA and inflammation parameters and decreasing topical glucocorticosteroid eye drops and systemic IMT. Adalimumab is generally safe for pediatric uveitis.

A peptide-based anti-Adalimumab antibody assay to monitor immune response to biologics treatment in juvenile idiopathic arthritis and childhood chronic non-infectious uveitis

Immune response to biologics treatment, while widely reported, yet fails to correlate with clinical outcomes and assay to assay comparison is often not possible. Hence, we developed a new peptide based-detection assay to stratify pediatric patients with juvenile idiopathic arthritis (JIA) or chronic non-infectious uveitis (CNU) and monitor anti-drug antibodies (ADAbs) formed as part of an immune response to treatment with the fully human monoclonal therapeutic antibody Adalimumab. Adalimumab derived synthetic peptides were optimized for maximum immunogenicity and were tested by SP-ELISA on a development cohort of 18 JIA and CNU treated patients. The two best performing peptides able to differentiate patient groups were selected for evaluation with a larger scale ELISA testing on a total of 29 sera from pediatric patients with JIA or CNU. The results of this peptide-based assay were compared to an in-house developed SPR biosensor ADAbs assay and a commercially available bridging ELISA. The first peptide, termed HC3, was able to positively detect ADAbs in 7 out of the 29 sera, while the second peptide, called LC3, was able to detect ADAbs in 11 out of 29 sera in the evaluation group. Following statistical data evaluation, it has been found that the detection of ADAbs using the peptide-based ELISA assay positively correlates with disease progression and remission. Two synthetic peptides derived from Adalimumab may provide a beneficial tool to clinicians for monitoring patient response to such treatment and taking informed decisions for treatment alternatives.

Advances in Juvenile Spondyloarthritis

PURPOSE

To provide an overview of recent studies on pathogenesis, diagnosis, and management of juvenile spondyloarthritis (JSpA).

RECENT FINDINGS

Recent studies show differences in gut microbiome in patients with JSpA in comparison to healthy controls. There is increased recognition of the impact of the innate immune system on disease pathology. Normative reference on MRI of sacroiliac (SI) joints in children is now available. However, there is significant variability in interpretation of MRI of SI joints in children and a need for standardization. NSAIDs, physical therapy, and Tumor Necrosis Factor Inhibitors (TNFi) remain the mainstay of management for patients with JIA who have polyarthritis, sacroiliitis, and/or enthesitis as per recent ACR guidelines. Newer therapeutic options beyond TNFi are needed to manage patients who fail TNFi. This review highlights some of the recent advances in our knowledge of JSpA pathophysiology, diagnosis, and treatment. It also identifies areas in need of further research and standardization to improve our understanding and outcomes in JSpA.

Biomarkers of Response to Biologic Therapy in Juvenile Idiopathic Arthritis

Background: Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthritis of childhood, characterized by various clinical phenotypes associated with variable prognosis. Significant progress has been achieved with the use of biologic treatments, which specifically block pro-inflammatory molecules involved in the disease pathogenesis. The most commonly used biologics in JIA are monoclonal antibodies and recombinant proteins targeting interleukins 1 (IL-1) and 6 (IL-6), and tumor necrosis factor α (TNF-α). Several biomarkers have been investigated in JIA. Aims: To assess the level of evidence available regarding the role of biomarkers in JIA related to guiding clinical and therapeutic decisions, providing disease prognostic information, facilitating disease activity monitoring and assessing biologic treatment response in JIA, as well as propose new strategies for biologic therapy-related biomarker use in JIA. Methods: We searched PubMed for relevant literature using predefined key words corresponding to several categories of biomarkers to assess their role in predicting and assessing biologic treatment response and clinical remission in JIA. Results: We reviewed serological, cellular, genetic, transcriptomic and imaging biomarkers, to identify candidates that are both well-established and widely used, as well as newly investigated in JIA on biologic therapy. We evaluated their role in management of JIA as well as identified the unmet needs for new biomarker discovery and better clinical applications. Conclusion: Although there are no ideal biomarkers in JIA, we identified serological biomarkers with potential clinical utility. We propose strategies of combining biomarkers of response to biologics in JIA, as well as routine implementation of clinically acceptable imaging biomarkers for improved disease assessment performance.

Treatment of Juvenile Spondyloarthritis: Where We Stand

Juvenile spondyloarthritis is a subset of juvenile idiopathic arthritis (JIA) with onset in late childhood and adolescence and a strong association with human leukocyte antigen (HLA) B-27 positivity and familial aggregation that has the potential for axial involvement, potentially leading to ankylosing spondylitis. Current therapy for severe disease relies heavily on tumor necrosis factor inhibitors (TNFi). Treatment paradigms in children largely consist of extrapolation from studies on adults with spondyloarthritis. Additional therapies studied in adults include non-steroidal anti-inflammatory drugs (NSAIDs), blockade of the interleukin-17 (IL-17) and IL-23 axes, blockade of T-cell stimulation, phosphodiesterase (PDE)-4 inhibition, and Janus-activated kinase (JAK) pathway alteration. IL-17 blockade and IL-23 blockade are guideline approved after TNFi failure (and even as an alternative to TNFi) in adults, depending on concomitant inflammatory bowel and skin disease, with JAK and PDE-4 inhibition options following biologic failure. Neither pediatric nor adult guidelines address IL-6 blockade, T-cell co-stimulation blockade, or combination biologic therapy.

Towards therapeutic drug monitoring of TNF inhibitors for children with juvenile idiopathic arthritis: a scoping review

OBJECTIVES

Before a clinician decides whether treatment with TNF inhibition in children with JIA has failed, one should ensure adequate systemic exposure has been achieved. Therapeutic drug monitoring might allow for improved treatment outcome with lower treatment-associated costs. However, this requires understanding of the pharmacokinetic (PK) characteristics, and the pharmacokinetic/pharmacodynamic (PK/PD) relationship for children with JIA. We performed a scoping review to summarize the available literature and identify areas for future research.

METHODS

A systematic search was conducted of the Medline, EMBASE, Web of Science and Cochrane databases as well as the clinicaltrials.gov registry. In total, 3959 records were screened and 130 publications were selected for full text assessment.

RESULTS

Twenty publications were included and divided into three categories: PK (n = 9), PK/PD (n = 3) and anti-drug antibodies (n = 13). Industry involvement was significant in 14 publications. Although data are limited, systemic exposure to TNF inhibitors is generally lower in younger children but meta-analysis is not possible. The PK/PD relationship has had limited study but there is partial evidence for infliximab. Anti-drug antibodies are common, and are related to impaired clinical outcome with adalimumab and infliximab therapy.

CONCLUSION

The current knowledge about the PK and PK/PD of TNF inhibitors in the treatment of children with JIA is limited, which prevents the introduction of TDM. Re-analysis of available data from previous trials, incorporation of pharmacologic assessments into existing biorepository studies as well as new prospective PK and PK/PD trials are required to obtain this knowledge.

Immunogenicity of biologic agents in juvenile idiopathic arthritis: a systematic review and meta-analysis

OBJECTIVE

The clinical impact of anti-drug antibodies (ADAbs) in paediatric patients with JIA remains unknown. This systematic review and meta-analysis aimed to summarize the prevalence of ADAbs in JIA studies; investigate the effect of ADAbs on treatment efficacy and adverse events; and explore the effect of immunosuppressive therapy on antibody formation.

METHODS

PubMed, Embase and the Cochrane Library were systematically searched to identify relevant clinical trials and observational studies that reported prevalence of ADAbs. Studies were systematically reviewed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses and appropriate proportional and pairwise meta-analyses were performed.

RESULTS

A total of 5183 references were screened; 28 articles, involving 26 studies and 2354 JIA patients, met eligibility criteria. Prevalence of ADAbs ranged from 0% to 82% across nine biologic agents. Overall pooled prevalence of ADAbs was 16.9% (95% CI, 9.5, 25.9). Qualitative analysis of included studies indicated that antibodies to infliximab, adalimumab, anakinra and tocilizumab were associated with treatment failure and/or hypersensitivity reactions. Concomitant MTX uniformly reduced the risk of antibody formation during adalimumab treatment (risk ratio 0.33; 95% CI 0.21, 0.52).

CONCLUSION

The association of ADAbs with treatment failure and hypersensitivity reactions indicates their clinical relevance in paediatric patients with JIA. Based on our findings, we recommend a preliminary course of action regarding immunogenicity of biologic agents in patients with JIA. Further strategies to predict, prevent, detect and manage immunogenicity could optimize treatment outcomes and personalize treatment with biologic therapies.

Recommendations for the Management of Uveitis Associated With Juvenile Idiopathic Arthritis: The Czech and Slovak adaptation of SHARE Initiative

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in children and uveitis is its most important extra-articular manifestation. Evidence-based recommendations are available only to a limited extent and therefore JIA associated uveitis management is mostly based on physicians experience. Consequently, treatment practices differ widely, both nationally and internationally. Therefore, an effort to optimize and publish recommendations for the care of children and young adults with rheumatic diseases was launched in 2012 as part of the international project SHARE (Single Hub and Access Point for Pediatric Rheumatology in Europe) to facilitate clinical practice for paediatricians and (paediatric) rheumatologists. The aim of this work was to translate published international SHARE recommendations for the diagnosis and treatment of JIA associated uveitis and to adapt them for use in the Czech and Slovak Republics. International recommendations were developed according to the standard methodology of the European League against Rheumatism (EULAR) by a group of nine experienced paediatric rheumatologists and three experts in ophthalmology. It was based on a systematic literature review and evaluated in the form of an online survey and subsequently discussed using a nominal group technique. Recommendations were accepted if &gt; 80% agreement was reached (including all three ophthalmologists). A total of 22 SHARE recommendations were accepted: 3 on diagnosis, 5 on disease activity assessment, 12 on treatment and 2 on future recommendations. Translation of the original text was updated and modified with data specific to the czech and slovak health care systems and supplemented with a proposal for a protocol of ophthalmological dispensarization of paediatric JIA patients and a treatment algorithm for JIA associated uveitis. Conclusion: The aim of the SHARE initiative is to improve and standardize care for paediatric patients with rheumatic diseases across Europe. Therefore, recommendations for the diagnosis and treatment of JIA-associated uveitis have been formulated based on the evidence and agreement of leading European experts in this field.

Treating juvenile idiopathic arthritis (JIA)-related uveitis beyond TNF-α inhibition: a narrative review

Chronic anterior uveitis is the most frequent among extra-articular manifestations of juvenile idiopathic arthritis (JIA) and a relevant cause of ocular morbidity in children. Asymmetric arthritis, early onset disease, female sex, and anti-nuclear antibody (ANA) positivity are counted among risk factors for developing this complication. It usually has insidious onset and asymptomatic chronic-relapsing course, but the persistence of low-grade chronic inflammation can lead to irreversible structural ocular damage and to vision-threatening complications. For such reasons, achieving a complete absence of inflammation through early targeted and aggressive treatments is a primary therapeutic goal in these patients. This review is aimed at summarizing scientific evidence about biologic rescue therapy of JIA-related uveitis in patients who fail to achieve clinical remission, in spite of being treated with conventional disease-modifying anti-rheumatic drugs (cDMARDs) and at least one biologic tumor necrosis factor (TNF)-α inhibitor. Interleukin (IL)-6 inhibition appears a promising and safe option for refractory JIA-related uveitis. Abatacept and rituximab proved to be beneficial as well, but their efficacy together with some safety concerns needs to be more extensively evaluated.

Drug monitoring in long-term treatment with adalimumab for juvenile idiopathic arthritis-associated uveitis

OBJECTIVES

Assessing influence of anti-adalimumab (ADA) antibodies (AAA) on serum trough ADA levels and uveitis activity in long-term ADA treatment of juvenile idiopathic arthritis (JIA)-associated uveitis.

PATIENTS AND INTERVENTIONS

This prospective observational study included 20 patients from a single centre treated with ADA for active uveitis refractory to conventional disease-modifying antirheumatic drugs. AAA, serum ADA trough levels and uveitis activity were evaluated at regular intervals up to 6 years.

RESULTS

AAA were detected in nine patients (45%). Permanent AAA in seven were associated with undetectable ADA trough levels and loss of response (LOR). Transient AAA were detected in four with measurable ADA trough levels and response of uveitis to treatment, followed in two by permanent AAA associated with LOR. Use of concomitant immunosuppression was significantly higher in patients without AAA (p<0.05).

CONCLUSIONS

AAA-associated LOR frequently occurs in long-term treatment with ADA for JIA-associated uveitis. Concomitant immunosuppressive therapy significantly reduces the risk of LOR due to AAA.

Risks associated with use of TNF inhibitors in children with rheumatic diseases

Introduction: Tumor necrosis factor alpha (TNF-α) is a pro-inflammatory cytokine involved in the pathogenesis of many inflammatory diseases. Several drugs blocking TNF-α are employed in clinical practice in pediatrics. Given their action on the immune system, TNF-α inhibitors have raised concerns on their safety profile since their introduction. A broad spectrum of side effects related to TNF inhibition has been reported: immunogenicity, infectious diseases, malignancies, and others. Areas covered: In order to assess the risk related to the use of anti-TNF-α agents in children with rheumatic diseases we analyzed data obtained from retrospective and prospective safety studies, case reports and case series, and controlled trials. Expert commentary: Anti-TNF-α agents have shown a remarkably good safety profile in the pediatric population so far. However, there are lots of questions to be answered and maintaining active surveillance on these drugs is necessary in order to not overlook any possible unexpected adverse effects.

Consensus-based recommendations for the management of uveitis associated with juvenile idiopathic arthritis: the SHARE initiative

BACKGROUND

In 2012, a European initiative called Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) was launched to optimise and disseminate diagnostic and management regimens in Europe for children and young adults with rheumatic diseases. Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in children and uveitis is possibly its most devastating extra-articular manifestation. Evidence-based guidelines are sparse and management is mostly based on physicians' experience. Consequently, treatment practices differ widely, within and between nations.

OBJECTIVES

To provide recommendations for the diagnosis and treatment of JIA-associated uveitis.

METHODS

Recommendations were developed by an evidence-informed consensus process using the European League Against Rheumatism standard operating procedures. A committee was constituted, consisting of nine experienced paediatric rheumatologists and three experts in ophthalmology from Europe. Recommendations derived from a validated systematic literature review were evaluated by an Expert Committee and subsequently discussed at two consensus meetings using nominal group techniques. Recommendations were accepted if >80% agreement was reached (including all three ophthalmologists).

RESULTS

In total, 22 recommendations were accepted (with >80% agreement among experts): 3 on diagnosis, 5 on disease activity measurements, 12 on treatment and 2 on future recommendations.

CONCLUSIONS

The SHARE initiative aims to identify best practices for treatment of patients suffering from JIA-associated uveitis. Within this remit, recommendations for the diagnosis and treatment of JIA-associated uveitis have been formulated by an evidence-informed consensus process to suggest a standard of care for JIA-associated uveitis patients throughout Europe.

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

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

Current Practices for Therapeutic Drug Monitoring of Biopharmaceuticals in Pediatrics

Biopharmaceuticals have recently emerged as effective treatments for refractory pediatric autoimmune conditions. Several reports have shown a relationship between drug concentration, antidrug antibodies, and clinical response in these patients, strongly suggesting the potential interest, usefulness, and reliability of therapeutic drug monitoring (TDM) in children. This article reviews the current state of research in juvenile idiopathic arthritis, pediatric inflammatory bowel disease, and pediatric psoriasis from a TDM point of view. There is a remarkable lack of evidence-based data in pediatric patients, which is reflected throughout the article. Most investigations of TDM are focused on research of tumor necrosis factor alpha antagonists in inflammatory bowel disease, albeit preliminary publications are emerging from pediatric rheumatologists and dermatologists. To date, immunogenicity has been a primary concern, particularly regarding infliximab and adalimumab therapy in children, as it may lead to a loss of therapeutic response. Preliminary investigations show that adjusting the dose according to blood drug concentrations improves disease outcomes by overcoming antidrug antibodies, suggesting a crucial role for TDM. Patients who receive other drugs, such as etanercept, abatacept, or tocilizumab, could benefit from TDM because dosage can be optimized by adjusting it to the minimum effective dose.

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.