An Examination of the Mechanisms Involved in Secondary Clinical Failure to Adalimumab or Etanercept in Inflammatory Arthropathies:

Next-Generation Anti-TNFα Agents: The Example of Ozoralizumab

Biologic therapy involving anti-tumor necrosis factor-α (anti-TNFα) agents has fundamentally changed the management of patients with immune-mediated inflammatory diseases, including rheumatoid arthritis, thus benefiting many patients. Nevertheless, the inability of some patients to achieve low disease activity or clinical remission remains a major concern. To address such concerns, next-generation anti-TNFα agents that differ from the immunoglobulin G-format anti-TNFα agents that have been used to date are being developed using antibody-engineering technology. Their unique design employing novel molecular characteristics affords several advantages, such as early improvement of clinical symptoms, optimization of drug bioavailability, enhancement of tissue penetration, and a reduction in side effects. This holds promise for a new paradigm shift in biologic therapy via the use of next-generation anti-TNFα agents. Ozoralizumab, a next-generation anti-TNFα agent that was recently approved in Japan, comprises a variable region heavy-chain format. It has a completely different structure from conventional therapeutic antibodies, such as a small molecular size, an albumin-binding module, and a unique format that produces an avidity effect. Ozoralizumab exhibited rapid biodistribution into joints, provided attenuation of Fcγ receptor-mediated inflammatory responses, and had a high binding affinity to TNFα in non-clinical studies. In clinical trials, ozoralizumab yielded an early improvement in clinical symptoms, a sustained efficacy for up to 52 weeks, and an acceptable tolerability in patients with rheumatoid arthritis. This review focuses on the results of pre-clinical and clinical trials for ozoralizumab and outlines the progress in next-generation antibody development.

No Correlation between Anti-drug Antibodies and Therapeutic Response in Tunisian Patients with Chronic Inflammatory Diseases Treated by TNF Blockers

INTRODUCTION

Tumor necrosis factor alpha (TNF alpha) blockers such as infliximab (IFX) and adalimumab (ADA) had significantly changed the course of inflammatory diseases such as rheumatoid arthritis (RA), spondyloarthritis (SpA) and Crohn's disease (CD). However, about 30% of patients do not respond to these treatments. This lack of response may be due to the formation of antibodies against these drugs (anti-drug antibodies: ADAbs). The aim of this study was to determine the prevalence of ADAbs against IFX and ADA, and the trough serum concentration of IFX and ADA in RA, SpA or CD patients and to assess their impact on the therapeutic response.

METHODS

A cross sectional, multi-centric study was conducted, including patients with RA, SpA or CD treated with IFX or ADA as a first biotherapy for at least 6 months. ADAbs and trough levels were measured by an Enzyme Linked Immunosorbent assay (ELISA).

RESULTS

197 patients were included (57 RA, 73 SpA and 67 CD). ADAbs were positive in 40% of cases for IFX and 25% for ADA. They were positive in 40% of SpA, 35% of RA, and 21% of CD. The presence of ADAbs was inversely correlated to the trough levels of IFX and ADA during RA (p = 0.01 and p < 0.0001), SpA (p < 0.01 and p < 0.0001) and CD (p = 0.001 and p = 0.04). For all pathologies, the presence of ADAbs was not correlated with disease activity. Concomitant methotrexate significantly reduced immunogenicity.

CONCLUSION

In our study, the presence of ADAb and low trough levels seem to not affect the therapeutic response in patients on TNF alpha antagonists. Other tracks more than immunogenicity should be investigated to explain the loss of response to these biotherapies.

Management of patients with inflammatory rheumatic diseases after treatment failure with a first tumour necrosis factor inhibitor: A narrative review

The emergence of biologics with different modes of action (MoAs) and therapeutic targets has changed treatment patterns in patients with inflammatory rheumatic diseases. While tumour necrosis factor inhibitors (TNFis) are often utilized as the first biologic disease-modifying antirheumatic drug, some patients may not respond adequately (primary failure), fail to sustain response over time (secondary failure), or experience intolerable adverse events. Whether these patients would benefit more from cycling to a different TNFi or switching to a biologic with a different MoA is still unclear. We discuss here treatment outcomes of TNFi cycling versus MoA switching after treatment failure with a first TNFi in patients with inflammatory rheumatic diseases, focusing specifically on rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, and juvenile idiopathic arthritis. Treatment guidelines for these patients are ambiguous and, at times, contradictory in their recommendations. However, this is due to a lack of high-quality head-to-head data to definitively support cycling between TNFis after failure to a first-line TNFi over switching to a different MoA.

Treatment Failure in Axial Spondyloarthritis: Insights for a Standardized Definition

Axial spondyloarthritis is a chronic inflammatory rheumatic disease that affects the axial skeleton and causes severe pain and disability. It may be also associated with extra-articular manifestations. Early diagnosis and appropriate treatment can reduce the severity of the disease and the risk of progression. The biological disease-modifying antirheumatic drugs (bDMARDs) tumor necrosis factor alpha (TNFα) inhibitors (TNFi) and the anti-interleukin (IL)-17A antibodies secukinumab and ixekizumab are effective agents to reduce disease activity and minimize the inflammation that damages the joints. New alternatives such as Janus kinase (JAK) inhibitors are also available. Unfortunately, response rates to bDMARDs are far from optimal, and many patients experience so-called treatment failure. The definition of treatment failure definition is often vague and may depend on the rigorousness of the therapeutic goal, the inclusion or not of peripheral symptoms/extra-articular manifestations, or patients' overall health. After an exhaustive bibliographic review, we propose a definition based on loss of the following status: low disease activity assessed by Ankylosing Spondylitis Disease Activity Score (ASDAS)-CRP, absence of extra-articular manifestations, and low disease impact on the patients' general health. Apart from discontinuing the therapy because of safety or intolerance reasons, two types of treatment failure can be differentiated depending on when it occurs: primary failure (no response within 6 months after treatment initiation, or lack of efficacy) and secondary failure (response within 6 months but lost thereafter, or loss of efficacy over time). Physicians should carefully consider the moment and the reason for the treatment failure to decide the next therapeutic step. In the case of primary failure on a first TNFi, it seems reasonable to switch to another class of drugs, i.e., an anti-IL-17 agent, as phase III trials showed that the response to IL-17 blockade was higher than to placebo in patients previously exposed to TNFi. When secondary failure occurs, and loss of efficacy is suspected to be caused by antidrug antibodies (ADAs), it is advisable to analyze serum TNFi and ADAs concentrations, if possible; in the presence of ADAs and low TNFi levels, changing the TNFi is rational as it may restore the TNFα blocking capacity. If ADAs are absent/low with adequate drug therapeutic levels, switching to another target might be the best strategy.

Biologic use in psoriatic arthritis and ankylosing spondylitis patients: a descriptive epidemiological study using linked, routine data in Wales, UK

OBJECTIVES

PsA and AS are chronic diseases associated with significant morbidities. National and international management guidelines include treatment with biologic therapies to improve outcomes and quality of life. There are limited real-world data on the patients' journey from symptom onset to diagnosis and treatment in the UK. We use real-life, linked health data to explore patient pathways and the impact of biologics on patient outcomes.

METHODS

Data from the Secure Anonymised Information Linkage databank in Wales were used to assess diagnosis and treatment of patients ≥18 years of age with at least one International Classification of Diseases, Tenth Revision code present for PsA/AS in rheumatology clinic data and at least one Read code present in primary care records. We investigated the use of biologics while exploring demographics, comorbidities and surgical procedures of 641 AS patients and 1312 PsA patients.

RESULTS

AS patients were significantly younger at diagnosis and were predominantly male. The average time from presenting symptoms to diagnosis of AS and PsA was 7.9 (s.d. 5.5) and 9.3 (s.d. 5.5) years, respectively. The proportion of patients receiving biologic treatment was significantly higher in AS (46%) compared with PsA patients (28.8%); of these, 23.1% of AS and 22.2% of PsA patients stopped/switched a biologic. There was a significant reduction in primary care involvement, sick notes and disability living allowance for both AS and PsA patients following biologic initiation.

CONCLUSION

This real-world descriptive study confirms that patients treated with biologics have reduced disability and time off work despite being initiated ∼13 years after the first symptoms and 6 years after diagnosis.

Impact of immunogenicity on clinical efficacy and toxicity profile of biologic agents used for treatment of inflammatory arthritis in children compared to adults

The treatment of inflammatory arthritis has been revolutionised by the introduction of biologic treatments. Many biologic agents are currently licensed for use in both paediatric and adult patients with inflammatory arthritis and contribute to improved disease outcomes compared with the pre-biologic era. However, immunogenicity to biologic agents, characterised by an immune reaction leading to the production of anti-drug antibodies (ADAs), can negatively impact the therapeutic efficacy of biologic drugs and induce side effects to treatment. This review explores for the first time the impact of immunogenicity against all licensed biologic treatments currently used in inflammatory arthritis across age, and will examine any significant differences between ADA prevalence, titres and timing of development, as well as ADA impact on therapeutic drug levels, clinical efficacy and side effects between paediatric and adult patients. In addition, we will investigate factors associated with differences in immunogenicity across biologic agents used in inflammatory arthritis, and their potential therapeutic implications.

Anti-TROVE2 Antibody Determined by Immune-Related Array May Serve as a Predictive Marker for Adalimumab Immunogenicity and Effectiveness in RA

Anti-drug antibody (ADAb) development is associated with secondary therapeutic failure in biologic-treated rheumatoid arthritis (RA) patients. With a treat-to-target goal, we aimed to identify biomarkers for predicting ADAb development and therapeutic response in adalimumab-treated patients. Three independent cohorts were enrolled. In Cohort-1, 24 plasma samples (6 ADAb-positive and 6 ADAb-negative patients at baseline and week 24 of adalimumab therapy, respectively) were assayed with immune-related microarray containing 1,636 correctly folded functional proteins. Next, we executed statistically powered autoantibody profiling analysis of 50 samples in Cohort-2 (24 ADAb-positive and 26 ADAb-negative patients). Subsequently, immunofluorescence assay was performed on 48 samples in Cohort-3 to correlate with ADAb titers and drug levels. The biomarkers were identified for predicting ADAb development and therapeutic response using the immune-related microarray and machine learning approach. ADAb-positive patients had lower drug levels at week 24 (median = 0.024 μg/ml) compared with ADAb-negative patients (median = 6.38 μg/ml, p < 0.001). ROC analysis based on the ADAb status revealed the top 20 autoantibodies with AUC ≥ 0.7 in differentiating both groups in Cohort-1. Analysis of Cohort-2 dataset identified a panel of 8 biomarkers (TROVE2, SSB, NDE1, ZHX2, SH3GL1, CARD9, PTPN20, and KLHL12) with 80.6% specificity, 77.4% sensitivity, and 79.0% accuracy in discriminating poor from EULAR responders. Immunofluorescence assay validated that anti-TROVE2 antibody could highly predict ADAb development and poor EULAR response (AUC 0.79 and 0.89, respectively). Multivariate regression analysis proved anti-TROVE2 antibody to be an independent predictor for developing ADAb. Immune-related protein microarray and replication analysis identified anti-TROVE2 antibody as a useful biomarker for predicting ADAb development and therapeutic response in adalimumab-treated patients.

Exposure-Response Relationship of Certolizumab Pegol and Achievement of Low Disease Activity and Remission in Patients With Rheumatoid Arthritis

Anti-tumor necrosis factor (anti-TNF) drugs are often prescribed for the treatment of rheumatoid arthritis (RA) and other immune-mediated inflammatory diseases. Although this treatment has been shown to be effective in many patients, up to 40% of patients do not achieve disease control. Drug concentration in plasma may be a factor affecting the observed variability in therapeutic response. In this study, we aimed to identify the plasma concentrations of the anti-TNF certolizumab pegol (CZP), associated with improvement in disease activity in patients with RA. Data were pooled from three randomized, controlled clinical trials with a combined total of 1,935 patients analyzed. Clinical outcomes of low disease activity (LDA) and remission were defined as Disease Activity Score in 28 joints with C-reactive protein (DAS28(CRP)) ≤ 2.7 and < 2.3, respectively. Quartile analysis results indicated that there may be an exposure-response relationship between CZP concentration and LDA/remission outcomes at weeks 12 and 24; the association was strongest for LDA (P < 0.05). Receiver operating characteristic (ROC) analysis showed that CZP concentrations ≥ 28.0 μg/ml at week 12, and ≥ 17.6 μg/ml at week 24, were associated with a greater likelihood of achieving LDA/remission outcomes. Although confirmatory studies are warranted to define the optimal CZP therapeutic range at weeks 12 and 24, these data indicate that CZP concentrations may be associated with improvement of disease activity.

The Effect of Tumor Necrosis Factor-Alpha Inhibitors on Uveitis in Patients with Ankylosing Spondylitis

BACKGROUND

Tumor necrosis factor-alpha (TNF-α) inhibitors (TNFis), which are the main treatment for ankylosing spondylitis (AS), have been reported not only to reduce the incidence of anterior uveitis (AU) but also to induce it, and these effects differ among the various types of TNFis in clinical use. The present study investigated the effect of TNFis on uveitis by analyzing the long-term clinical course of AU in AS patients treated with TNFi therapy.

METHODS

Patients treated with at least one TNFi between January 2007 and July 2017 were reviewed, and 54 patients with at least one episode of AU were included in this study. The TNFis included anti-TNF-α antibodies (adalimumab, infliximab, and golimumab), and a soluble TNF receptor molecule (etanercept). The effect of prevention of AU, the likelihood of new-onset uveitis after the initiation of TNFi therapy, and the effects of drug switching and dose escalation were assessed.

RESULTS

The first uveitis flare was observed before TNFi therapy in 39 patients and after TNFi therapy in 15 patients. Anti-TNF-α antibodies were more efficacious in decreasing the recurrence of AU than etanercept. Among patients in which uveitis first occurred after beginning TNFi therapy, patients on etanercept tended to first develop AU less than 1 year after starting the drug, and their AS tended to be well-controlled at the time of uveitis flares. Patients with a uveitis flare before their medication was switched did not recur afterwards, and five of eight patients showed no relapse after dose escalation.

CONCLUSION

TNFis have various effects on AU. TNFis, particularly anti-TNF-α antibodies, should be considered in patients with AS and frequent AU relapse. Additionally, clinicians should consider whether AU is due to an absence of a therapeutic response of AS to TNFi treatment or to TNFi treatment itself, and appropriate treatment changes should be made accordingly.

How to Get the Most from Methotrexate (MTX) Treatment for Your Rheumatoid Arthritis Patient?-MTX in the Treat-to-Target Strategy

Methotrexate (MTX) is a remarkable drug with a key role in the management of rheumatoid arthritis (RA) at every stage of its evolution. Its attributes include good overall efficacy for signs and symptoms, inhibition of structural damage and preservation of function with acceptable and manageable safety, a large dose-titratable range, options for either an oral or parenteral route of administration, and currently unrivalled cost-effectiveness. It has a place as a monotherapy and also as an anchor drug that can be safely used in combination with other conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or used concomitantly with biological DMARDs or targeted synthetic DMARDs. MTX is not without potential issues regarding toxicity, notably hepatotoxicity and bone marrow toxicity, as well as tolerability problems for some, but not all, patients. But many of these issues can be mitigated or managed. In the face of a welcome expansion in available targeted therapies for the treatment of RA, MTX looks set to remain at the foundation of pharmacotherapy for the majority of people living with RA and other inflammatory rheumatic diseases. In this article, we provide an evidence-based discussion as to how to achieve the best outcomes with this versatile drug in the context of a treat-to-target strategy for the management of RA.

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

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

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Safety and tolerability of adalimumab for the treatment of psoriasis: a review summarizing 15 years of real-life experience

Biologic therapies like adalimumab are the gold standard for psoriasis treatment with efficacy and safety profiles allowing for long-term treatment. However, adalimumab cannot be used in all patients and may cause adverse drug reactions. This study reviews conditions that might limit the use of adalimumab under real-life conditions. Local injection site reactions affect 12-37% of patients but rarely require specific therapy. Dermatological adverse events (AEs) include the paradoxical psoriasis and tend to respond to adequate therapy without adalimumab discontinuation. Adalimumab increases the risk for infections; latent chronic infections like tuberculosis or hepatitis B/C impose the highest risk for serious AEs. However, administration of adalimumab may still be possible under appropriate monitoring or prophylactic therapy. Some studies indicate an increased risk of malignancies in patients with psoriasis exposed to adalimumab. Here, the causal relationship is unclear since both psoriasis and some first-line therapies increase the risk of malignancies. Depression frequently coincides with psoriasis and may respond to adalimumab as well. Cardiovascular diseases are contraindications for adalimumab, but evidence suggests that adalimumab may still be a treatment option. Overall AE rates range from 245 to 399 per 100 patient years (serious AEs: 6-23; death: 1-2). Thus, adalimumab is slightly less safe than ustekinumab and infliximab but exhibits superior effectiveness and drug survival. Adalimumab is safe for pregnant women during the first trimester, for children up to 4 years and for the elderly. Thus, in spite of several conditions that require specific attention, the favourable safety and tolerability of adalimumab for the treatment of psoriasis is confirmed.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Essential Medicines List Implementation Dynamics: A Case Study Using Brazilian Federal Medicines Expenditures

The aim was to analyse the implementation dynamics of the essential medicines list (EML). We used the government expenditures on medicines and Brazil as a case study. Drug purchases were considered as a proxy for utilization. The essential medicines (EMs) expenditures were followed over time by Brazilian National EMLs life-time and defined by broad therapeutic categories and by specific medicines. Brazil increased the number of the medicines during the last four editions of Brazilian National EMLs and the federal government expenditures on them. The EML implementation dynamics changed the distribution of expenditures on EMs. We identified a common set of 404 EMs present in all four editions of the Brazilian National EMLs. There was a proportional decrease in expenditures on anti-infectives for systemic use, blood and blood-forming organs and alimentary tract and metabolism, and increase in expenditures on antineoplastic and immunomodulating agents. The expenditures distribution per specific medicines revealed that a small set of EMs was responsible for 50% or more of expenditures considering Brazilian National EML life-time for all four periods. The increase in expenditures on EMs in Brazil was a consequence of the newer medicines incorporated over time in the Brazilian National EMLs. The use of the medicines expenditures as a source of data and the definition of an EML life-time permitted follow-up of the implementation dynamics of different versions of the Brazilian National EMLs. Our results have implications for policymakers and stakeholders to gain a better understanding of the role EMLs play in health system sustainability and in the provision of the most beneficial heath care.

Whole genome analysis on the genetic backgrounds associated with the secondary failure to etanercept in patients with rheumatoid arthritis

OBJECTIVES

Etanercept is effective for the treatment of rheumatoid arthritis (RA). However, some of the patients eventually lose efficacy (secondary failure) despite the absence of neutralizing antibodies. We aimed to explore single nucleotide polymorphisms (SNPs) associated with secondary failure.

METHODS

We recruited RA patients given etanercept at 50 mg/week for ≥6 months from the Matsubara Mayflower Hospital RA registry. They were assigned to responders, secondary failure patients, and non-responders according to Disease Activity Score. Genome-wide association study (GWAS) was performed using Illumina HumanHAP300k BeadChips and the results were analyzed with Plink software. Clinical backgrounds were compared by ANOVA and contingency table analysis. The protocol was approved by IRB and written informed consent was obtained.

RESULTS

Ninety, 27 and 17 patients were assigned to responders, secondary failure patients, and non-responders, respectively. No significant differences were observed regarding clinical backgrounds among the groups. GWAS revealed that six and 37 SNPs may be associated with secondary failure to etanercept with p< 10^-6 and <10^-5, respectively.

CONCLUSION

While our preliminary results with borderline significance should be validated by studies with a greater population size, some of the SNPs detected by our GWAS may be involved in the development of secondary failure to etanercept.

Antibodies to infliximab in Remicade-treated rheumatic patients show identical reactivity towards biosimilars

OBJECTIVES

The aim of this study was to determine whether antibodies to infliximab (IFX) in Remicade-treated patients cross-react with the biosimilar CT-P13.

METHODS

250 consecutive patients with rheumatic diseases under Remicade and 77 controls were retrospectively selected for the study. Anti-IFX antibodies at drug through levels were measured in parallel with three different bridging ELISA assays: Promonitor-ANTI-IFX kit, which uses Remicade to detect antibodies, and two more assays that use either Inflectra or Remsima with the same format. Correlation and association between each assay was studied.

RESULTS

50.4% of patients were tested positive with Promonitor-ANTI-IFX. All were antibodies to IFX (ATI)-positive when either Inflectra or Remsima assays were used. In all comparisons positive and negative percentage agreements were 100%, and correlation coefficients were ≥0.995. No differences between rheumatoid arthritis and spondyloarthritis, or between concomitant immunosuppressives, were observed.

CONCLUSIONS

Anti-IFX antibodies of Remicade-treated patients cross-react with either Inflectra or Remsima. Although additional epitopes may be present in the biosimilar, results suggest that epitopes influencing the immune response to IFX are also present in the biosimilar. Antibody-positive patients treated with Remicade should not be switched to the biosimilar, since antibodies will interact with the new drug and potentially lead to loss of response. This finding supports the utility for therapeutic drug monitoring before a switching strategy is considered.