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Immunogenicity assessment is vital in clinical trials and is measured through a multi-tiered approach (screening, confirmatory and titer assays). However, recent studies have suggested that titer results could be reported from ADA signal-to-noise ratios (S/N ratios=sample mean signal/negative control mean signal). More data analysis using two clinical trials of adalimumab: SB5-1003 (single-dose, healthy participants) and SB5-4001 (multiple-dose, interchangeability study, patients with plaque psoriasis), therefore, is indispensable whether substituting ADA S/N ratio as an alternative way of reporting titer results has no impact on interpretation on clinical outcome. In this study, we demonstrated that there is a strong correlation between S/N ratios and titers and no impact on overall PK results. Nonetheless, sub-analyses with time or adalimumab level showed a change in the regression between S/N ratios and titers, leading to different titer values from the same S/N ratio. These data demonstrate that S/N ratios may fully replace titers in limited circumstances such as a biosimilar study which goal is to prove equivalence between the originator and candidate product, but need a caution in other cases., Competing Interests: Declarations Conflict of Interest The authors declare no conflicts of interest. Clinical Trial Registry [SB5-1003] 1.Trial registry name: clinicaltrials.gov2.Registration identification number: NCT045147963.The URL for the registry for the clinical trials performed: https://clinicaltrials.gov/study/NCT04514796?intr=SB5&rank=2.[SB5-4001] 1.Trial registry name: clinicaltrials.gov2.Registration identification number: NCT055100633.The URL for the registry for the clinical trials performed: https://clinicaltrials.gov/study/NCT05510063?intr=SB5&rank=4., (© 2024. The Author(s).)

Objective: This post hoc analysis compared the immunogenicity of the biosimilar adalimumab-adbm (Cyltezo) with the adalimumab reference product (RP; Humira) across indications, including rheumatoid arthritis (RA), Crohn's disease (CD) and plaque psoriasis (PsO), and by patient sex in the VOLTAIRE trials programme., Methods: In each active-comparator randomised controlled trial (RCT), immunogenicity was assessed at various time points by the proportion of patients with antidrug antibodies (ADAs) and neutralising antibodies (nAbs), using acid dissociation followed by electrochemiluminescence assay. Assay sensitivity was 50 ng/mL, and drug tolerance was ≥30 µg/mL (free drug) at the low positive control level., Results: Minor differences in immunogenicity parameters (ADAs, ADA titres and nAbs) were evident between adalimumab-adbm and adalimumab RP across these three immune-mediated inflammatory diseases (IMIDs). The proportion of ADA-positive and nAb-positive patients increased from baseline over time in all three RCTs, as expected, and was similar in the RA and CD RCTs but with higher numbers of ADA-positive and nAb-positive patients reported in the PsO trial. Subgroup analysis by patient sex showed the same trend., Conclusions: Differences among the RCTs may partially be explained by concomitant background therapy (methotrexate) in the RA trial, stable doses of azathioprine, 6-mercaptopurine or methotrexate in 36% of patients with CD and absence of background therapy in the PsO RCT. The analyses further confirm the biosimilarity of adalimumab-adbm with the adalimumab RP across IMIDs and provide supporting evidence that adalimumab-adbm is an interchangeable biosimilar with consistent clinical results in patients originally treated with the RP., Trial Registration Numbers: VOLTAIRE-RA (NCT02137226; EudraCT 2012-002945-40); VOLTAIRE-CD (NCT02871635; EudraCT 2016-000612-14); VOLTAIRE-PsO (NCT02850965; EudraCT 2016-000613-79)., Competing Interests: Competing interests: VS reports consulting for AbbVie, Amgen, Aria, AstraZeneca, Bayer, Bioventus, BlackRock, BMS, Boehringer Ingelheim, Celltrion, ChemoCentryx, Equillium, Gilead, Genentech/Roche, Glenmark, GSK, Horizon, Inmedix, Janssen, Kiniksa, Kypha, Lilly, Merck, MiMedx, Novartis, Pfizer, Priovant, Regeneron, Rheos, R-Pharma, Samsung, Sandoz, Sanofi, Scipher, Setpoint, Sorrento, Spherix and Tonix. SB reports previous employment by Boehringer Ingelheim Pharmaceuticals. DM reports previous employment by Boehringer Ingelheim Pharmaceuticals., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Detecting antidrug antibodies (ADAs) against infliximab or adalimumab is useful for therapeutic drug monitoring. Various ADA detection methods exist, and antibody titer is an output in some algorithms. Homogenous mobility shift assay (HMSA) measures relative ADA concentration and determines drug-ADA complex size in vitro. However, the relevance of complex size determination in drug monitoring remains unclear. Hence, the association between complex size, ADA concentration, and sample detectable neutralizing activity was evaluated., Methods: Sera from infliximab-treated and adalimumab-treated patients who tested positive for ADA in the National Screening Service were analyzed using 3 ADA assays. HMSA determined the relative ADA concentrations and complex sizes, competitive ligand-binding assay evaluated the sample neutralizing capacity, and enzyme-linked immunosorbent assay detected immunoglobulin (Ig)G4 ADA., Results: Most ADA-positive samples (>80%) formed drug-ADA dimer complexes, whereas 17% had dimer and multimer complexes, and 3% had multimeric complexes. Multimer presence had 100% positive predictive value for detectable neutralizing activity. ADA concentration and detectable neutralizing activity were moderately correlated (r = 0.65) in adalimumab-treated patients and strongly correlated (r = 0.81) in infliximab-treated patients. In adalimumab-treated patients, multimer presence was a stronger predictor of neutralizing activity than ADA concentration was, but not in infliximab-treated patients. However, in infliximab-treated patient samples, multimer presence revealed a distinct subset with high ADA concentrations, neutralizing activity, and IgG4 ADA., Conclusions: Multimers detected using HMSA had a strong positive predictive value for competitive ligand-binding assay detectable neutralizing activity. Multimeric IgG4-containing ADA-drug complexes revealed a distinct subset of infliximab-treated patient samples, whose clinical relevance merits further investigation., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To review the prevalence, incidence, and risk factors for developing anti-drug antibodies (AAA) in patients with non-infectious uveitis (NIU) treated with Adalimumab (ADA)., Methods: A systematic literature search was performed on PubMed, EMBASE, Virtual Health Library, Cochrane, and medRxiv. Meta-analysis was performed using random effects., Results: Nine out of 2,373 studies were included. The prevalence of AAA in NIU patients treated with ADA was 9% (95% CI: 2% to 37%, I 2  = 95% with a P<0.01), it was significantly higher in real-life scenarios (observational studies) than in clinical trials. The pooled incidence at 12 months was 27% (CI 95% 16%-42% I 2  = 0%). Several factors have been associated with AAA generation in NIU patients, including the non-use of concomitant immunosuppressants, presence of autoimmune systemic disease, female gender, etc., Conclusion: This study showed that AAA prevalence is higher in real-life scenarios compared to clinical trials. Further research is needed to elucidate the factors that trigger AAA generation in NIU patients.

Objectives: Monitoring of therapeutic antibody adalimumab (ADL) and of anti-adalimumab antibodies (AAA) in autoimmune diseases patients' sera has achieved increased attention since several studies showed a correlation between AAA levels and treatment failure. We evaluated a new surface plasmon resonance (SPR)-based method that, with slight changes in the analysis condition and in the ligand immobilized on the chip surface, allows to monitor both AAA and ADL. This new label-free method does not require sample pretreatments, and it is fully automated, only requiring the preparation of the chip, which can be used for multiple analysis, and the preparation of the sample sets., Design & Methods: Sera from ADL-treated patients (n = 47) and controls (n = 13) were included in this study. Quantitative analysis of AAA and ADL were performed separately using a new SPR-biosensor, and a commercially available ELISA kit. Agreement was defined by overall, positive, and negative agreement. Wilson Score was used to calculate confidence intervals (CI) on binomial probability and Spearman's rho and Bland-Altman test were used to assess correlations., Results: ELISA and SPR-based assay were able to identify circulating AAA in ADL-treated patients, with the percentage of positivity varying among the methods, with an overall agreement of 79%. AAA were detected in 18 (38 %) out of the 47 treated patients by the ELISA whereas SPR-based assay detected 10 (21 %) out of 47 samples., Conclusions: Real-time label free SPR-based protocol for both AAA and ADL quantification has been set-up. Although quantitative differences were observed when compared with ELISA, the agreement among methodologies was high, particularly for ADL quantification within the therapeutic window of the drug., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Background: To evaluate the risk of neutropenia during treatment with anti-IL-23 antibodies in patients with psoriasis., Method: We conducted an observational study with cohort design using MID-NET ® in Japan. We identified patients with psoriasis who were newly prescribed anti-IL-23 antibodies, anti-IL-17-antibodies, adalimumab, or apremilast between January 1, 2009, and March 31, 2021. We estimated the adjusted hazard ratio (aHR) of anti-IL-23 antibodies compared to that of anti-IL-17 antibodies, adalimumab, or apremilast, for the risk of grade 2 (neutrophil count < 1,500/μL) or grade 3 (neutrophil count < 1,000/μL) neutropenia., Results: Overall, 287 patients on anti-IL-23 antibodies, 189 patients on anti-IL-17 antibodies, 293 patients on adalimumab, and 540 patients on apremilast were included. Compared with anti-IL-17 antibodies, the aHR (95% confidence interval (CI)) of anti-IL-23 antibodies was 0.83 (0.27-2.51) for grade 2 and 0.40 (0.02-7.60) for grade 3 neutropenia; that when compared with adalimumab was 0.76 (0.28-2.06) for grade 2 but was not calculated for grade 3 as no cases were found; and that compared with apremilast was 3.88 (0.62-24.48) for grade 2 and 0.43 (0.02-11.63) for grade 3 neutropenia., Conclusion: No clear increase in the risk of neutropenia with anti-IL-23 antibodies was observed.

Background: Adalimumab induces the production of anti-drug antibodies (ADA) that may lead to reduced drug concentration and loss-of-response, posing significant clinical challenges. However, traditional immunoassays have limitations in terms of sensitivity and drug-tolerance, hindering the insights of ADA response., Methods: Herein, we developed an integrated immunoassay platform combining the electrochemiluminescence immunoassay with immunomagnetic separation strategy. A longitudinal cohort study involving 49 patients with ankylosing spondylitis was carried out to analyze the dynamic profiles of ADA and to investigate the impact of ADA on adalimumab pharmacokinetics using a population pharmacokinetic model. Additionally, cross-sectional data from 12 patients were collected to validate the correlation between ADA levels and disease relapse., Results: The ADA assay demonstrated high sensitivity (0.4 ng/mL) and drug-tolerance (100 μg/mL), while the neutralizing antibodies (NAB) assay showed a sensitivity of 100 ng/mL and drug-tolerance of 20 μg/mL. Analysis of the longitudinal cohort revealed that a majority of patients (44/49, 90%) developed persistent ADA within the first 24 weeks of treatment. ADA levels tended to plateau over time after an initial increase during the early immune response phase. Further, nearly all of the tested patients (26/27, 96%) were classified as NAB positive, with a strong correlation between ADA levels and neutralization capacity (R 2 = 0.83, P < 0.001). Population pharmacokinetic modeling revealed a significant positive association between model-estimated individual clearance and observed ADA levels. Higher ADA levels were associated with adalimumab clearance and disease relapse in a cross-sectional cohort, suggesting a promising ADA threshold of 10 for potential clinical application. Moreover, the IgG class was the primary contributor to ADA against adalimumab and the apparent affinity exhibited an increasing trend over time, indicating a T-cell dependent mechanism for ADA elicitation by adalimumab., Conclusion: In summary, this integrated immunoassay platform shows promise for in-depth analysis of ADA against biologics, offering fresh insights into immunogenicity and its clinical implications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Ding, Xue, Wang, Zhu, Zhu, Jiang, Wu and Miao.)

Monitoring anti-drug antibodies (ADAs) to infliximab and adalimumab is critical to treatment management in various autoimmune disorders. The growing need for proactive therapeutic monitoring further requires the detection of ADAs in the presence of measurable concentrations of infliximab or adalimumab. To provide robust analytical assays for clinical application, we evaluated two automated immunoassays developed using ImmunoCAP™ technology and based on the bridging format to measure serum ADAs to infliximab and adalimumab respectively. Without an acid-dissociation step, these research prototype assays can detect a positive control monoclonal ADA towards infliximab and adalimumab, ranging from < 25 ng/ml to 10,000 ng/mL. Both assays exhibit imprecision less than 20% at different ADA titer levels and can distinguish ADAs towards different drug targets. In method comparison using authentic patient samples, the quantitative results of the ADA assays are not directly comparable to two existing clinical immunoassays for ADAs (correlation coefficient r s  = 0.673 for infliximab ADAs; r s  = 0.510 for adalimumab ADAs), presumably due to the lack of commutable ADA standards and the polyclonal nature of ADAs. Nevertheless, there is qualitative agreement between the methods when evaluating putative positive and negative patient samples (overall agreement 0.83 for infliximab ADAs; 0.76 for adalimumab ADAs). Biotin and high levels of rheumatoid factors may interfere with the performance of the automated assays due to competitive binding with the biotinylated drug and non-specific formation of bridging complexes. The two ImmunoCAP assays can provide new analytical methods for proactive therapeutic monitoring of adalimumab and infliximab., (© 2024. The Author(s).)

Objective: VOLTAIRE-HCLF compared the relative bioavailability of citrate-free high-concentration and reference formulations of the biosimilar adalimumab-adbm (Cyltezo®), including pharmacokinetic (PK) profiles, immunogenicity, and safety profiles in healthy volunteers., Methods: Healthy volunteers ( N  = 200) aged 18-55 years and with body mass index of 18.5-29.9 kg/m 2 and no prior exposure to adalimumab were randomized in a 1:1 ratio to receive a single subcutaneous injection of either adalimumab-adbm 40 mg/0.4 mL (high-concentration formulation) or 40 mg/0.8 mL (reference formulation). Participants completed 13 follow-up visits over 57 days, followed by a safety follow-up period of up to 70 days., Results: The main PK parameters were similar for the high-concentration and reference groups. For all primary endpoints, the geometric mean ratios and 90% confidence intervals of AUC 0-1344 , AUC 0-∞ , and C max for both groups were entirely within the standard 80-125% bioequivalence acceptance range at 101.88% (93.31-111.23%), 105.38% (95.06-116.81%), and 91.29% (84.38-98.76%), respectively. There were no differences in the proportion of anti-drug antibody-positive participants or in the distribution of anti-drug antibody titers between the two formulations at any time point after drug dosing. Participants who were given the high-concentration formulation of adalimumab-adbm experienced a lower incidence of adverse events and local reactions than those who were given the reference formulation., Conclusions: Overall, the high-concentration and reference adalimumab-adbm formulations had highly similar PK and immunogenicity profiles and were safe and well tolerated., Clinical Trial Registration: NCT05203289.

Objectives: To explore associations between serum adalimumab level, treatment response and drug survival in order to identify optimal drug levels for therapeutic drug monitoring of adalimumab. Also, to assess the occurrence and risk factors of anti-drug antibody (ADAb) formation., Methods: Non-trough adalimumab and ADAb levels were measured by automated fluorescence assays in serum collected after 3 months of adalimumab treatment in patients with RA, PsA or axial SpA (axSpA) included in the observational NOR-DMARD study. Treatment response was evaluated after 3 months and drug survival was evaluated during long-term follow-up., Results: In 340 patients (97 RA, 69 PsA, 174 axSpA), the median adalimumab level was 7.3 mg/l (interquartile range 4.0-10.3). A total of 33 (10%) patients developed ADAbs. Findings were comparable across diagnoses. In RA and PsA, adalimumab levels ≥6.0 mg/l were associated with treatment response [odds ratio (OR) 2.2 (95% CI 1.0, 4.4)] and improved drug survival [hazard ratio 0.49 (95% CI 0.27, 0.80)]. In axSpA, a therapeutic level could not be identified, but higher adalimumab levels were associated with response. Factors associated with ADAb formation were previous bDMARD use, no methotrexate comedication and the use of adalimumab originator compared with GP2017., Conclusion: Higher adalimumab levels were associated with a better response and improved drug survival for all diagnoses, with a suggested lower threshold of 6.0 mg/l for RA/PsA. This finding, the large variability in drug levels among patients receiving standard adalimumab dose and the high proportion of patients developing ADAbs encourages further investigations into the potential role of therapeutic drug monitoring of adalimumab., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

In this work we have generated cattle-derived chimeric ultralong CDR-H3 antibodies targeting tumor necrosis factor α (TNF-α) via immunization and yeast surface display. We identified one particular ultralong CDR-H3 paratope that potently neutralized TNF-α. Interestingly, grafting of the knob architecture onto a peripheral loop of the CH 3 domain of the Fc part of an IgG1 resulted in the generation of a TNF-α neutralizing Fc (Fc knob ) that did not show any potency loss compared with the parental chimeric IgG format. Eventually, grafting this knob onto the CH 3 region of adalimumab enabled the engineering of a novel TNF-α targeting antibody architecture displaying augmented TNF-α inhibition., (© 2024 the author(s), published by De Gruyter, Berlin/Boston.)

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., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Objective: Anti-drug antibodies (ADA) to anti-tumour necrosis factor (anti-TNF) therapy drive treatment loss of response. An association between intestinal microbial composition and response to anti-TNF therapy was noted. We therefore aimed to assess the implications of antibiotic treatments on ADA formation in patients with inflammatory bowel disease (IBD)., Design: We analysed data from the epi-IIRN (epidemiology group of the Israeli IBD research nucleus), a nationwide registry of all patients with IBD in Israel. We included all patients treated with anti-TNF who had available ADA levels. Survival analysis with drug use as time varying covariates were used to assess the association between antibiotic use and ADA development. Next, specific pathogen and germ-free C57BL mice were treated with respective antibiotics and challenged with infliximab. ADA were assessed after 14 days., Results: Among 1946 eligible patients, with a median follow-up of 651 days from initiation of therapy, 363 had positive ADA. Cox proportional hazard model demonstrated an increased risk of ADA development in patients who used cephalosporins (HR=1.97, 95% CI 1.58 to 2.44), or penicillins with β-lactamase inhibitors (penicillin-BLI, HR=1.4, 95% CI 1.13 to 1.74), whereas a reduced risk was noted in patients treated with macrolides (HR=0.38, 95% CI 0.16 to 0.86) or fluoroquinolones (HR=0.20, 95% CI 0.12 to 0.35). In mice exposed to infliximab, significantly increased ADA production was observed in cephalosporin as compared with macrolide pretreated mice. Germ-free mice produced no ADA., Conclusion: ADA production is associated with the microbial composition. The risk of ADA development during anti-TNF therapy can possibly be reduced by avoidance of cephalosporins and penicillin-BLIs, or by treatment with fluoroquinolones or macrolides., Competing Interests: Competing interests: YC received research grants, speaker and advisory fees from AbbVie; speaker and advisory fees from Janssen; grant, speaker and advisory fees from Takeda and consultancy fees from CytoReason. SSO received grant funding from Takeda, holds equity and receives consultancy fees from CytoReason. SG-V declares CytoReason advisory fees for last 3 years. RK received consultation fee, research grant, royalties or honorarium from Takeda and Pfizer. ID received consultation fee, research grant or honorarium from Janssen, AbbVie, Takeda, Pfizer, Roche/Genentech, Celgene/BMS, Arena, Neopharm, Gilead, Gallapagos, Celltrion, Ferring, Falk Pharma, MSD, DSM, Cambridge Healthcare, Sublimity, Sangamo, Nestle, Wild bio, Food Industries Association, Integran Holdings, Abbott, Altman Research, (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Data on outcomes following de-escalation of intensified anti-TNF therapy in inflammatory bowel disease (IBD) are limited and concerns about relapse limit willingness to de-escalate., Aims: To evaluate rates of successful de-escalation at 12 months and to determine factors that may predict success., Methods: Single-centre experience of IBD patients that were de-escalated following deep remission on dose-intensified infliximab (IFX) or adalimumab (ADA) for secondary loss of response. Patients were classified as 'successes' if remaining on reduced anti-TNF or 'failures' if requiring re-escalation, steroids, surgery or enrolment into a clinical trial at 12 months. Patient demographics, disease characteristics, biomarkers (faecal calprotectin, C-reactive protein, albumin) and anti-TNF drug levels were collected 6-monthly., Results: Of 25 patients (20 CD, 5 UC), 16 (64%) were successes 12 months post-de-escalation. Median time to failure was 6 months. Six of the nine failures required anti-TNF re-escalation and three entered a clinical trial. Re-escalation recaptured response in all six patients. There was no significant difference in baseline biomarker activity between the two groups. There was no difference in infliximab levels between successes and failures at the time of de-escalation (5.5 vs. 5.3, p = 0.63) as well as 6 months (3.1 vs. 4.6, p = 0.95) and 12 months (3.2 vs. 4.5, p = 0.58) post-de-escalation., Conclusion: Nearly two-thirds of patients remained on reduced anti-TNF dosing 12 months after de-escalation. All patients who failed de-escalation were recaptured after dose re-escalation. De-escalation with close monitoring may be considered in patients on intensified anti-TNF therapy in sustained remission., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: The objective of this study was to assess the relationship between adalimumab trough concentrations and treatment response in paediatric patients with JIA., Methods: This was a monocentric cohort study of JIA patients treated with adalimumab. Clinical data and samples were collected during routine follow-up. Adalimumab trough concentrations were quantified by a novel liquid chromatography-tandem mass spectrometry assay. Anti-adalimumab antibodies were measured in samples with trough concentrations of ≤5mg/l. Disease activity was evaluated using the clinical Juvenile Arthritis DAS with 71-joint count (cJADAS71). Response to adalimumab was defined according to recent international treat-to-target guidelines., Results: A total of 35 adalimumab trough samples were available from 34 paediatric patients with JIA. Although there was no significant difference in adalimumab dose, trough concentrations were significantly lower in patients with secondary failure [median 1.0 mg/l; interquartile range (IQR) 1.0-5.3] compared with patients with primary failure (median 13.97 mg/l; IQR 11.81-16.67) or an adequate response (median 14.94 mg/l; IQR 10.31-16.19) to adalimumab., Conclusion: Adalimumab trough concentrations were significantly lower in JIA patients with secondary failure compared with patients with primary failure or an adequate response to adalimumab. Our results suggest that trough concentration measurements could identify JIA patients who require increased adalimumab doses to achieve or maintain therapeutic drug concentrations., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Monoclonal antibodies (mAbs) are one of the most significant molecules in protein therapeutics. They are employed in the field of immunology, oncology and organ transplant. They have been also been employed for alleviating several bacterial and viral infections. Moreover, they have revolutionized the area of targeted therapy and improved the quality of treatments, as compared to other cytotoxic drugs and therapies. mAbs bind to specific molecules on the antigen and exhibit specificity towards that molecule, i.e. epitope. Thus, mAbs have immense opportunity to be explored for personalized therapy. The introduction of targeted mAb-based therapeutics has promoted many important scientific achievements in rheumatology. This has warranted additional investigations for developing newer mAb producing clones, to supplement the limited industrial production of certain mAb therapeutics. In this investigation, an integrative approach comprising optimized expression, selection and expansion was adopted to develop a mammalian cell line expressing mAb against TNF-α.The resulting stable clone is anticipated to serve as an economic alternative to the industrial clones, especially for research purposes. The clone was constructed for development of biosimilar of the highly valued therapeutic antibody, Humira., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Immunogenicity related to treatment with TNF inhibitors (TNFi) is one of the causes for the decreased attainment of clinical response in patients with rheumatoid arthritis (RA). The B-cell activating factor (BAFF) may be playing a role in the development of immunogenicity. The objective of this study was to analyse the association of baseline concentration of serum B-cell activating factor (BAFF) with immunogenicity after 6 months of TNFi treatment. A total of 127 patients with RA starting a TNFi (infliximab, adalimumab, certolizumab pegol or golimumab) were followed-up for 6 months. Serum samples were obtained at baseline and at 6 months and anti-drug antibody (ADA) and BAFF concentrations were measured. Logistic regression models were employed in order to analyse the association between BAFF concentrations and immunogenicity. Receiver operating characteristic analysis was performed to determine the BAFF concentrations with a greater likelihood of showing immunogenicity association. At 6 months, 31 patients (24%) developed ADA. A significant interaction between the age and baseline BAFF concentration was found for the development of ADA (Wald chi-square value = 5.30; p = 0.02); therefore, subsequent results were stratified according to mean age (≤ / > 55 years). Baseline serum BAFF concentration was independently associated with ADA development only in patients over 55 years (OR = 1.51; 95% CI 1.03-2.21). Baseline serum BAFF ≥ 1034 pg/mL predicted the presence of ADA at 6 months (AUC = 0.81; 95% confidence interval (CI) 0.69-0.93; p = 0.001; positive likelihood ratio = 3.7). In conclusion, our results suggest that the association of BAFF concentration and immunogenicity depends on the patient's age. Baseline serum BAFF concentration predicts the presence of ADA within 6 months of TNFi therapy in older patients with RA.

Background: Anti-tumor necrosis factor (TNF) drugs have improved the prognosis for juvenile idiopathic arthritis (JIA) significantly. However, evidence for individual treatment decisions based on serum anti-TNF drug levels and the presence of anti-drug antibodies (ADAbs) in children is scarce. We aimed to assess if anti-TNF drug levels and/or ADAbs influenced physician's treatment decisions in children with JIA., Methods: Patients' records in our center were retrospectively screened for measurements of anti-TNF drug levels and ADAbs in children with JIA using etanercept, adalimumab or infliximab. Clinical characteristics and disease activity were retrieved from patient charts., Results: We analyzed 142 measurements of anti-TNF drug levels in 65 children with JIA. Of these, ninety-seven (68.3%) were trough concentrations. N = 14/97 (14.4%) of these showed trough concentrations within the therapeutic drug range known for adults with RA and IBD. ADAbs against adalimumab were detected in seven patients and against infliximab in one patient. Seven (87,5%) of these ADAb-positive patients had non-detectable drug levels. A flowchart was made on decisions including rational dose escalation, stopping treatment in the presence of ADAbs and undetectable drug levels, showing that 45% of measurements influenced treatment decisions, which concerned 65% of patients (n = 42/65)., Conclusions: In the majority of patients, measurement of anti-TNF drug levels led to changes in treatment. A wide variation of anti-TNF drug levels was found possibly due to differences in drug clearance in different age groups. There is need for determination of therapeutic drug ranges and pharmacokinetic curves for anti-TNF and other biologics in children with JIA.

Glycoengineering of therapeutic proteins has been applied to improve the clinical efficacy of several therapeutics. Here, we examined the effect of glycosylation on the properties of the Fab of the therapeutic antibody, adalimumab. An N-glycosylation site was introduced at position 178 of the H chain constant region of adalimumab Fab through site-directed mutagenesis (H:L178N Fab), and the H:L178N Fab was produced in Pichia pastoris. Expressed mutant Fab contained long and short glycan chains (L-glyco Fab and S-glyco Fab, respectively). Under the condition of aggregation of Fab upon pH shift-induced stress, both of L-glyco Fab and S-glyco Fab were less prone to aggregation, with L-glyco Fab suppressing aggregation more effectively than the S-glyco Fab. Moreover, the comparison of the antigenicity of glycosylated and wild-type Fabs in mice revealed that glycosylation resulted in the suppression of antigenicity. Analysis of the pharmacokinetic behaviour of the Fab, L-glyco Fab and S-glyco Fab indicated that the half-lives of glycosylated Fabs in the rats were shorter than that of wild-type Fab, with L-glyco Fab having a shorter half-life than S-glyco Fab. Thus, we demonstrated that the glycan chain influences Fab aggregation and immunogenicity, and glycosylation reduces the elimination half-life in vivo., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.)

The primary objective of this randomized, double-blind, parallel-controlled study (from December 2016 to October 2018) was to evaluate pharmacokinetic (PK) equivalence of adalimumab biosimilar HLX03 and reference adalimumab in healthy volunteers, and to assess safety, and immunogenicity of HLX03. The primary PK endpoints were maximum observed plasma concentration (C max ) and area under the concentration curve from time zero to the last quantifiable concentration (AUC 0-t ). Equivalence was determined if the 90% confidence interval (CI) of geometric least square mean ratio between the two treatment groups were within the predefined range of 80%-125%. Safety and immunogenicity were monitored during the study. Healthy Chinese males (N = 220) were randomized 1:1 to receive a single subcutaneous 40 mg dose of HLX03 or China (CN)-sourced adalimumab. The ratios of the geometric mean of C max and AUC 0-t were 102.2% and 105.7%, respectively, with corresponding 90% CIs falling in the predefined margins, which demonstrated PK equivalence between HLX03 and CN-adalimumab. The incidence of treatment-emergent adverse events (TEAEs) was similar in the two groups (73.8% and 66.0% in the HLX03 and CN-adalimumab groups, respectively). Grade 3-4 TEAEs were reported in 7.5% and 5.7% of participants, respectively. The incidences of participants with antidrug antibodies (HLX03: 96.2%; CN-adalimumab: 93.4%) or neutralizing antibodies (HLX03: 40.6%, CN-adalimumab: 41.4%) were comparable between groups. This study demonstrated PK bioequivalence between HLX03 and CN-adalimumab, with similar safety and immunogenicity profiles. These data support further clinical development of HLX03 as an adalimumab biosimilar., (© 2021 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.)

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  μ g/ml) compared with ADAb-negative patients (median = 6.38  μ g/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., Competing Interests: The authors declare no competing interests., (Copyright © 2021 Po-Ku Chen et al.)

Biologic drugs, especially anti-TNF, are considered as the gold standard therapy in rheumatoid arthritis. However, non-uniform efficacy, incidence of infections, and high costs are major concerns. Novel tissue-specific agents may overcome the current limitations of systemic administration, providing improved potency, and safety. We developed a bispecific antibody (BsAb), combining human arthritic joint targeting, via the synovial-specific single-chain variable fragment (scFv)-A7 antibody, and TNFα neutralization, via the scFv-anti-TNFα of adalimumab, with the binding/blocking capacity comparable to adalimumab -immunoglobulin G (IgG). Tissue-targeting capacity of the BsAb was confirmed on the human arthritic synovium in vitro and in a synovium xenograft Severe combined immune deficient (SCID) mouse model. Peak graft accumulation occurred at 48 h after injection with sustained levels over adalimumab-IgG for 7 days and increased therapeutic effect, efficiently decreasing tissue cellularity, and markers of inflammation with higher potency compared to the standard treatment. This study provides the first description of a BsAb capable of drug delivery, specifically to the disease tissue, and a strong evidence of improved therapeutic effect on the human arthritic synovium, with applications to other existing biologics., Competing Interests: CP is an author in a patent related to the A7 antibody. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ferrari, Onuoha, Fossati-Jimack, Nerviani, Alves, Pagani, Deantonio, Colombo, Santoro, Sblattero and Pitzalis.)

This study aimed to directly analyze the potential relationship of anti-nuclear antibodies (ANA) before and after the administration of TNF-α inhibitors (TNFi) with the appearance of anti-drug antibodies (ADrA) in patients with rheumatoid arthritis (RA). A total of 121 cases, viz., 38, 53, and 30 cases treated with infliximab (IFX), adalimumab (ADA), and etanercept (ETN), respectively, were enrolled. The ANA titers were measured using indirect immunefluorescence assay (IF-ANA) and multiplex flow immunoassay (ANA Screen) before and serially during the therapy. The anti-IFX antibodies (HACA) and anti-ADA antibodies (AAA) were measured with a radioimmunoassay. ADrA turned positive in 14 (36.8%) among 38 patients treated with IFX, and 16 (30.2%) among 53 treated with ADA. All of them were positive for IF-ANA before TNFi administration, while ADrA never appeared in any of the 15 patients negative for IF-ANA (< 40). IF-ANA of high titers (≥ 320 and ≥ 640) before IFX treatment showed a significant association with the appearance of HACA 52 weeks after IFX (P = 0.040 and 0.017, respectively), whereas AAA appearance was not related to IF-ANA titers before treatment. Moreover, IF-ANA of high titers before IFX treatment was significantly associated with inefficacy and discontinuation of the treatment. The positivity of anti-SS-A antibodies before therapy might be a risk factor for ADrA appearance in patients treated with IFX or ADA. The percentage of patients whose IF-ANA titers increased was significantly higher with IFX than with ADA or ETN treatments (P = 0.026 and 0.022, respectively). High ANA titers and positive ANA Screen after IFX therapy showed a significant association with HACA appearance and possibly led to treatment failure. Among the three TNFi, only IFX showed a close relationship with IF-ANA and ADrA appearance, suggesting the interaction of immunogenicity with autoimmunity as well as the advantage of ANA measurement before TNFi therapy., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: SK received research grant from Chugai Pharmaceutical Co., Ono Pharmaceutical Co., Mitsubishi Tanabe Pharma, and Asahikasei Pharma. SK received consigned research fund for developing new test kits from Bio-Rad Laboratories Co. Japan and Sekisui Medical Co. SK has been a consultant of SYSMEX CORPORATION. These do not alter the authors’ adherence to PLOS ONE policies on sharing data and materials. The authors except SK have declared no conflicts of interests for this study.

Patients with rheumatoid arthritis (RA) are frequently treated with anti-tumor necrosis factor- α immunoglobulin therapy but develop neutralizing antibodies against these drugs, necessitating therapeutic monitoring of drug concentrations and anti-drug antibodies. Patients with RA have multiple factors related to their autoimmune disposition that interfere with conventionally used methods to detect anti-drug antibodies. Currently deployed analytical methods have significant limitations that hinder clinical interpretation and/or routine use, and no method can detect immunogenicity and drug levels simultaneously to provide clinically meaningful recommendations. Given these limitations, the objective of this study was to identify sources of and associations with assay interference in patients with RA. We designed a modular immunogenicity and drug concentration detection technology to identify the factors that interfere with the detection of adalimumab and anti-adalimumab antibodies in a cohort of 206 patients with RA. Patients were included from the University of Pittsburgh Rheumatoid Arthritis Comparative Effectiveness Research registry. In this cohort, we analyzed clinical and plasma factors associated with anti-adalimumab and anti-hinge antibodies. A novel flow cytometry-based assay was developed and validated that simultaneously measures adalimumab and anti-adalimumab antibody concentrations, overcoming many of the interference factors that are limitations of conventional assays, including anti-fragment crystallizable (Fc) and anti-hinge antibodies. C-reactive protein ( P = 0.035), Disease Activity Score-28 (DAS28) score ( P = 0.002), and disease activity category ( P = 0.009) were significantly associated with anti-adalimumab antibodies but not with anti-hinge antibodies ( P > 0.05). Anti-hinge antibodies were inversely associated with drug-neutralizing antibodies ( P = 0.002). In patients with RA, anti-hinge antibodies may have a potential protective effect against the development of anti-adalimumab antibodies. SIGNIFICANCE STATEMENT: Using a novel cytometric assay that simultaneously measures drug and anti-drug antibodies, we overcame many interferences that hinder the clinical interpretation of adalimumab immunogenicity testing. Our investigation in patients with RA demonstrated that immunogenicity impaired the pharmacological action of adalimumab via analysis of RA disease severity markers. We also demonstrate that patients with anti-hinge antibodies had lower anti-adalimumab antibody levels and decreased drug neutralization. Our results suggest that anti-hinge antibodies can predict adalimumab immunogenicity before the start of therapy., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2020 by The American Society for Pharmacology and Experimental Therapeutics.)

We report a case of a child with severe psoriasis vulgaris that developed neutralizing anti-drug antibodies against the biologic agent adalimumab 3 months after the first administration of the drug during Streptococcus pyogenes infection of the throat. After replacement of biologic agent, she was unsuccessfully treated with etanercept. Treatment with ustekinumab was the last option and initially it also appeared ineffective, but as we shortened the interval and doubled the dosage our patient's skin condition finally improved.

Aim: This study, FKB327-003, is a phase 3, open-label extension (OLE) study comparing the long-term immunogenicity of an adalimumab biosimilar, FKB327 (F), with the reference product (RP)., Methods: In the OLE, patients completing 24 weeks of an initial randomized, double-blind (DB) study (Period 1) with clinical response and no safety concerns were rerandomized to F or RP, so that two-thirds of patients remained on the same treatment and one-third switched to the alternate treatment for weeks 24 through 54 (OLE weeks 0-30; Period 2), then all received F through week 100 (OLE week 76; Period 3). Treatment sequences were F-F-F (no switch), RP-F-F and RP-RP-F (single switch), and F-RP-F (double switch). Patients who entered the OLE study were evaluated for immunogenicity across switching sequences., Results: The proportion of patients with positive antidrug antibody (ADA) status at the end of Period 1 was 61.7% and 60.0% for F and RP, respectively. The proportion of patients with positive ADA status did not increase throughout Period 1, and was similar for F and RP at all time points. At the end of Period 3, the proportion of patients with positive ADA status was lower in all treatment sequences, at 51.1%, 54.4%, 48.1%, and 42.5% for F-F-F, F-RP-F, RP-F-F, and RP-RP-F, respectively., Conclusion: The RP and F showed comparable immunogenicity characteristics after long-term administration. Development of ADAs with the RP and F was similar, and was not impacted by switching and double switching between F and RP treatment., (© 2020 The Authors. International Journal of Rheumatic Diseases published by Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.)

Background: Immunoassays based on label-free technologies (label-free immunoassay [LFIA]) offer an innovative approach to clinical diagnostics and demonstrate great promise for therapeutic drug monitoring (TDM) of monoclonal antibody (mAb) drugs. An LFIA measures immunocomplex formation in real time and allows for quantification on initial binding rate, which facilitates fast measurement within a few minutes., Methods: Based on thin-film interferometry (TFI) technology, open-access LFIAs were developed for the quantification of the mAb drugs adalimumab (ADL) and infliximab (IFX) and for the detection of the antidrug antibodies (ADAs) to the mAb drugs (ADL-ADAs and IFX-ADAs)., Results: The LFIAs for active mAb drugs (ADL and IFX) and for ADAs (ADL-ADAs and IFX-ADAs) were validated. The analytical measurement range (AMR) for both ADL and IFX was from 2 to 100 μg/mL. The AMR for ADL-ADAs was from 5 to 100 μg/mL and for IFX-ADAs was 10 to 100 μg/mL. In the comparison of LFIAs and reporter gene assays, the correlation coefficient was 0.972 for the quantification of ADL and 0.940 for the quantification of IFX. The concordance rate was 90% for the detection of ADL-ADAs and 76% for the detection of IFX-ADAs., Conclusions: The LFIAs for active mAb drugs and ADAs were appropriate for the TDM of ADL and IFX. The TFI technology has unique advantages compared with other technologies used for the measurement of mAb drugs. Label-free technologies, especially those allowing for open-access LFIAs, have great potential for clinical diagnostics., (© American Association for Clinical Chemistry 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The use of biologic-based therapeutics has revolutionized our ability to treat complex diseases such as cancer- and autoimmune-related disorders. Biologic-based therapeutics are known to generate anti-drug immune responses or immunogenicity in clinical patients which can lead to altered pharmacokinetics, decreased drug efficacy, and unwanted adverse clinical events. Assays designed to detect and assess anti-drug immune responses are used to help monitor patients and improve drug safety. Utilizing a tiered approach, screening assays are developed first to identify patients that are potentially positive for anti-drug-specific antibodies. Patients that screen positive are subjected to additional tiers of testing that include a confirmation assay to confirm the presence of expected anti-drug-specific antibodies, a titer assay to assess relative levels of anti-drug-specific antibodies, and, depending on the drug's mechanism of action or concerns of adverse clinical reactions, further characterization such as drug neutralization and anti-drug antibody isotyping. This tiered approach can prove to be detrimental to clinical samples from exposure to multiple cycles of testing, freeze thaws, and repeated handling by lab personnel. Multiplexing some of these assays together may streamline the characterization of anti-drug immune responses and help reduce the repeated usage of clinical samples. In this study, we combined a screening assay and anti-drug isotyping assays into one multiplexed assay using the Luminex® xMAP® Technology. The multiplexed assay was developed and validated to meet the FDA recommended guidelines for immunogenicity assessments. These results show that multiplexed assays perform comparably to industry standards. This study should encourage labs to explore the use of multiplexing immunogenicity assays to characterize anti-drug antibody responses quickly, with less repeat testing and reduced sample handling.

Background and Aims: Patients' perspectives after switching from originator to biosimilar adalimumab have yet to be assessed. We evaluated the efficacy of switching from the originator adalimumab to a biosimilar compound [SB5] in patients with inflammatory bowel disease [IBD]., Methods: Data on IBD patients who were switched from the originator to biosimilar adalimumab [SB5] at IBD Center ISCARE were analysed. Disease activity was assessed using standard clinical indices (Harvey-Bradshaw index [HBI] for Crohn's disease [CD] and partial Mayo score for ulcerative colitis [UC]), and laboratory parameters (C-reactive protein [CRP] and faecal calprotectin [FC]). Trough levels and anti-drug antibodies were measured. Patients were evaluated 10 weeks [W10] after the switch, and results were compared with the control group of patients on originator compound., Results: A total of 93 patients switched to biosimilar adalimumab were included [CD 86%] and were matched to 93 controls for age, gender, diagnosis, and disease activity. There was no difference in the disease activity in either SWITCH or ORIGINATOR cohorts between Weeks 0 and 10. Similarly, no difference was found between cohorts at both prespecified time points. Moreover, no significant differences in CRP or FC concentrations were seen between W0 and W10 either in the SWITCH, or in the ORIGINATOR cohort [p >0.05]. Adalimumab serum trough levels remained stable after the switch. No new safety signals were detected., Conclusions: Our study confirmed that switching IBD patients from the originator adalimumab to a biosimilar compound [SB5] does not affect treatment efficacy., (Copyright © 2020 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: After adalimumab treatment failure, tumour necrosis factor inhibition (TNFi) and non-TNFi biological disease-modifying anti-rheumatic drugs (bDMARDs) are equally viable options on a group level as subsequent treatment in rheumatoid arthritis (RA) based on the current best evidence synthesis. However, preliminary data suggest that anti-adalimumab antibodies (anti-drug antibodies, ADA) and adalimumab serum levels (ADL) during treatment predict response to a TNFi as subsequent treatment., Objective: To validate the association of presence of ADA and/or low ADL with response to a subsequent TNFi bDMARD or non-TNFi bDMARD. Sub-analyses were performed for primary and secondary non-responders., Methods: A diagnostic test accuracy retrospective cohort study was done in consenting RA patients who discontinued adalimumab after >3 months of treatment due to inefficacy and started another bDMARD. Inclusion criteria included the availability of (random timed) serum samples between ≥8 weeks after start and ≤2 weeks after discontinuation of adalimumab, and clinical outcome measurements Disease Activity Score in 28 joints - C-reactive protein (DAS28-CRP) between 3 to 6 months after treatment switch. Test characteristics for EULAR (European League Against Rheumatism) good response (DAS28-CRP based) after treatment with the next (non-)TNFi bDMARD were assessed using area under the receiver operating characteristic and sensitivity/specificity., Results: 137 patients were included. ADA presence was not predictive for response in switchers to a TNFi (sensitivity/specificity 18%/75%) or a non-TNFi (sensitivity/specificity 33%/70%). The same was true for ADL levels in patients that switched to a TNFi (sensitivity/specificity 50%/52%) and patients that switched to a non-TNFi (sensitivity/specificity 32%/69%). Predictive value of ADA and ADL were similar for both primary and secondary non-responders to adalimumab., Conclusions: In contrast to earlier research, we could not find predictive value for response to a second TNFi or non-TNFi for either ADA or random timed ADL., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: TNF-α blocker therapy is part of the treatment with biologics used in the management of inflammatory joint diseases. In recent years, drug-induced neutralizing antibodies have been shown to have a negative effect on the course of the disease process., Aim: To investigate drug-induced neutralizing antibodies against TNF-α blocking drugs used in patients with inflammatory joint diseases and their effect on the clinical course of the disease., Materials and Methods: The study included 121 (56.8%) patients with rheumatoid arthritis, 50 (23.5%) patients with ankylosing spondylitis, 42 (19.7%) patients with psoriatic arthritis, and 31 sex and age-matched healthy controls. The patients were monitored at 0, 6, 12, and 24 months after initiation of TNF-α blocker treatment. The demographic data, vital signs and the parameters of inflammatory activity (C-reactive protein, erythrocyte sedimentation rate, and disease activity indices) were analyzed in all patients. Drug-induced anti-TNF-α blockers antibodies (adalimumab and etanercept) were analyzed using ELISA. Statistical analysis was performed with SPSS v. 24., Results: Drug-induced neutralizing antibodies against adalimumab were obtained in 11.57% of patients at 6 month, in 17.64% at 12 month, and in 24.8% at 24 month. Drug-induced neutralizing antibodies to etanercept were not demonstrated in patients followed up at 6 months, at 7.77% at 12 months, and at 9.63% at 24 months. Between the presence of neutralizing antibodies to blockers of TNF-α and indices available for disease activity, there is a strong positive correlation and Pearson Correlation = 0.701, p=0.001. Patients with poor clinical response and available antibodies against adalimumab at 12 months were 82.36% and patients treated with etanercept 71.42%. The difference between the two groups was non-significant (U = 0.527, p> 0.05). Patients with poor clinical response and available anti-adalimumab antibodies at 24 month were 75%, and in patients treated with etanercept - 87.50%, the difference between the two groups not being able to reach significance (U = 0.623, p> 0.05)., Conclusion: Drug-induced neutralizing antibodies against TNF-α blockers (adalimumab and etanercept) have a negative effect on the course of inflammatory joint disease and can be used as reliable biomarker to assess the effect of the treatment with these drugs., (This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

This study aimed at exploring the concentration-effect relationship of adalimumab and early adalimumab and anti-adalimumab antibody (AAA) levels in predicting primary nonresponse in a real-world pilot cohort of patients with ankylosing spondylitis. Thirty-one patients were included. The Ankylosing Spondylitis Disease Activity Score improved with increasing adalimumab trough level at week 12 and reached a major improvement with levels between 8 and 12 μg/mL. Moreover, weeks 4 and 2 adalimumab levels below 4.28 and 3.37 μg/mL were predictive of primary nonresponse (area under the curve (AUC) = 0.89, 0.88; P = 0.0003, P = 0.034, respectively). Week 4 AAA signal-to-noise levels were significantly higher among primary nonresponders, and the cutoff for primary nonresponse prediction was above 5.31 (AUC = 0.81; P = 0.004). Adalimumab trough levels in a range of 8-12 μg/mL are optimum to reach major improvement, and lower adalimumab with higher AAA levels at the early stage (week 4) predict primary nonresponse by supporting proactive monitoring to optimize adalimumab therapy., (© 2020 The Authors. Clinical and Translational Science published by Wiley Periodicals, Inc. on behalf of the American Society for Clinical Pharmacology and Therapeutics.)

The immunogenicity of biotherapeutics presents a major challenge during the clinical development of new protein drugs including monoclonal antibodies. To address this, multiple humanization and de-immunization techniques that employ in silico algorithms and in vitro test systems have been proposed and implemented. However, the success of these approaches has been variable and to date, the ability of these techniques to predict immunogenicity has not been systematically tested in humans or other primates. This study tested whether antibody humanization and de-immunization strategies reduce the risk of anti-drug antibody (ADA) development using cynomolgus macaque as a surrogate for human. First human-cyno chimeric antibodies were constructed by grafting the variable domains of the adalimumab and golimumab monoclonal antibodies onto cynomolgus macaque IgG1 and Igκ constant domains followed by framework germlining to cyno to reduce the xenogenic content. Next, B and T cell epitopes and aggregation-prone regions were identified using common in silico methods to select domains with an ADA risk for additional modification. The resultant engineered antibodies had a comparable affinity for TNFα, demonstrated similar biophysical properties, and exhibited significantly reduced ADA levels in cynomolgus macaque compared with the parental antibodies, with a corresponding improvement in the pharmacokinetic profile. Notably, plasma concentrations of the engineered antibodies were quantifiable through 504 hours (chimeric) and 840 hours (germlined/de-immunized), compared with only 336 hours (adalimumab) or 336-672 hours (golimumab). The results point to the significant value in the investment in these engineering strategies as an important guide for monoclonal antibody optimization that can contribute to improved clinical outcomes., (© 2020 John Wiley & Sons, Ltd.)

Biological drugs, such as proteins and immunogens, are increasingly used to treat various diseases, including tumors and autoimmune diseases, and biological molecules have almost completely replaced synthetic drugs in rheumatology. Although biological treatments such as anti-tumor necrosis factor (TNF) drugs seem to be quite safe, they cause some undesirable effects, such as the onset of infections due to weakening of the immune system. Given the biological nature of these drugs, they might be recognized as extraneous; this would induce an immune reaction that neutralizes their effectiveness or lead to more serious consequences. Laboratories play a pivotal role in appropriate therapeutic management. The aim of this review was to underline the production of anti-drug antibodies during treatment with biological drugs and highlight the role of laboratories in ensuring appropriate use of these drugs., Competing Interests: None declared., (© The Korean Society for Laboratory Medicine.)

Objective: To assess the longitudinal production of anti-adalimumab antibody (AAA) and baseline risk factors for this antibody development in juvenile idiopathic arthritis (JIA) patients initiating adalimumab (ADA)., Method: Thirty consecutive JIA patients under ADA therapy were prospectively followed. JIA clinical/laboratorial/treatment data and sera for ADA and AAA assays (ELISA and bridging ELISA) were obtained at baseline (BL), 2 months (2M), 3 months (3M), 6 months (6M), 12 months (12M), and 24 months (24M). Patients with therapy failure requiring ADA withdrawn had their sera evaluated at their last medical visit prior to biologic switch (blinded to ADA and AAA levels)., Results: AAA was absent at BL, first detected at 2M after ADA initiation in 2/30 (7%) patients with a significant increase at 3M (10/29 (34%), p = 0.013) and no major change in 6M (11/30 (37%)) and 12M (9/26 (35%)). Of note, at 3M, AAA levels correlated negatively with ADA levels (r = - 0.781, p = 0.0001). Analysis of BL predictors revealed a significantly higher risk of developing AAA in patients with female gender (OR 21; 95% CI 1.08-406.57; p = 0.044), ESR > 30 mm/1st hour (OR 5.44; 95% CI 1.04-28.53; p = 0.045), and leflunomide use (OR 9.33; 95% CI 1.51-57.66; p = 0.016). In contrast, concomitant use of methotrexate was protective for AAA appearance (OR 0.08; 95% CI 0.01-0.53; p = 0.009). After 12M of ADA, 60% of AAA-positive patients required drug switch for drug failure compared with 15% in AAA-negative group (p = 0.03)., Conclusions: This study provides novel evidence of AAA production kinetics demonstrating a timely significant increase starting at 3M and stable throughout 24M. We also identified female gender, increased ESR, and leflunomide use as relevant risk factors for AAA production at BL, whereas methotrexate was protective. Early systematic monitoring of AAA at 3M may, therefore, guide drug switching in these patients.Key Points• Anti-adalimumab antibodies (AAA) production kinetics demonstrated a timely significant increase starting at 3M in juvenile idiopathic arthritis (JIA) patients under adalimumab therapy• Female gender, increased ESR, and leflunomide use were identified as relevant risk factors for AAA production in JIA, whereas methotrexate was protective.

The generation of anti-drug antibodies (ADAs) is one of the most serious problems in therapy using monoclonal antibodies (mAbs), because ADAs can impact the pharmacokinetics, efficacy, and safety of mAbs. It is therefore important to detect the generated ADAs in patients. For the appropriate detection of ADAs, methods that detect various types of ADAs (e.g., low- and high-affinity ADAs) are needed, but since there are no adequate reference preparations of ADAs relevant to human ADAs in most cases, it is difficult to determine whether or not the developed methods have enough analytical performance. Here, we developed human-rat chimeric ADA panels against the anti-TNF-α therapeutic antibodies infliximab and adalimumab. The developed ADA panels consist of 7 (for infliximab) and 11 (for adalimumab) ADAs with various binding characters, and most of the ADAs are neutralizing antibodies. Using these ADA panels, we compared the detectability of model methods, i.e., binding assays using SPR, BLI, and ECL, and a cell-based assay to detect neutralization activity. Since we obtained ADAs showing low and high responses with the various methods, the ADA panels we developed were shown to be useful for the development of ADA assays., (Copyright © 2019 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.)

Background & Aims: Anti-tumor necrosis factor (anti-TNF) therapies are the most widely used biologic drugs for treating immune-mediated diseases, but repeated administration can induce the formation of anti-drug antibodies. The ability to identify patients at increased risk for development of anti-drug antibodies would facilitate selection of therapy and use of preventative strategies., Methods: We performed a genome-wide association study to identify variants associated with time to development of anti-drug antibodies in a discovery cohort of 1240 biologic-naïve patients with Crohn's disease starting infliximab or adalimumab therapy. Immunogenicity was defined as an anti-drug antibody titer ≥10 AU/mL using a drug-tolerant enzyme-linked immunosorbent assay. Significant association signals were confirmed in a replication cohort of 178 patients with inflammatory bowel disease., Results: The HLA-DQA1*05 allele, carried by approximately 40% of Europeans, significantly increased the rate of immunogenicity (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.60-2.25; P = 5.88 × 10 -13 ). The highest rates of immunogenicity, 92% at 1 year, were observed in patients treated with infliximab monotherapy who carried HLA-DQA1*05; conversely the lowest rates of immunogenicity, 10% at 1 year, were observed in patients treated with adalimumab combination therapy who did not carry HLA-DQA1*05. We confirmed this finding in the replication cohort (HR, 2.00; 95% CI, 1.35-2.98; P = 6.60 × 10 -4 ). This association was consistent for patients treated with adalimumab (HR, 1.89; 95% CI, 1.32-2.70) or infliximab (HR, 1.92; 95% CI, 1.57-2.33), and for patients treated with anti-TNF therapy alone (HR, 1.75; 95% CI, 1.37-2.22) or in combination with an immunomodulator (HR, 2.01; 95% CI, 1.57-2.58)., Conclusions: In an observational study, we found a genome-wide significant association between HLA-DQA1*05 and the development of antibodies against anti-TNF agents. A randomized controlled biomarker trial is required to determine whether pretreatment testing for HLA-DQA1*05 improves patient outcomes by helping physicians select anti-TNF and combination therapies. ClinicalTrials.gov ID: NCT03088449., (Copyright © 2020 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Objectives: To compare the safety, efficacy, and immunogenicity of MSB11022 (acetate-buffered formulation), an adalimumab biosimilar, with the reference product., Method: AURIEL-RA study was a phase 3, multicenter, randomized, double-blind, parallel group trial (NCT03052322). Patients with moderately-to-severely active rheumatoid arthritis (RA) with an inadequate response to methotrexate were randomized 1:1 to MSB11022 or reference adalimumab. The primary endpoint was the incidence of treatment-emergent adverse events of special interest (AESIs) (predefined as hypersensitivity) up to week 52. The key secondary endpoint was ACR20 (≥ 20% improvement in American College of Rheumatology core set measurements from baseline) at week 12. Other efficacy endpoints, quality of life, immunogenicity, and pharmacokinetic parameters were evaluated up to week 52. Secondary safety endpoints were evaluated up to week 52 and at a 4-month safety follow-up., Results: In total, 288 patients were randomized. The proportion of patients experiencing ≥ 1 treatment-emergent AESI up to week 52 was similar between trial arms: 6 patients (4.2%; 95% CI 1.56, 8.91) receiving MSB11022, and 8 patients (5.5%; 95% CI 2.41, 10.58) receiving reference adalimumab. No clinically meaningful differences in efficacy, quality of life, or immunogenicity were seen between treatment arms up to week 52. No notable difference in the incidence of treatment-emergent adverse events was observed between treatment arms up to the end of the follow-up period., Conclusions: These results suggest MSB11022 and reference adalimumab are similar in patients with moderately-to-severely active rheumatoid arthritis in terms of safety, immunogenicity, and efficacy. AURIEL-RA provides evidence to support the similarity of MSB11022 and adalimumab.Key Points• Incidences of hypersensitivity events were similar for MSB11022 (modified buffer) and reference adalimumab.• There was no difference in local reactions between MSB11022 (modified buffer) and reference adalimumab.• AURIEL-RA confirms the equivalence in efficacy and immunogenicity of MSB11022 (modified buffer) and reference adalimumab.

Background: Treatment of pediatric inflammatory bowel disease (IBD) with monoclonal anti- tumor necrosis factor-alpha (TNFα) can result in immunogenicity and formation of anti-drug antibodies (ADAs). ADAs are associated with loss of clinical response and worsening disease progression. Data examining treatment interventions to overcome ADA in pediatric patients with IBD are lacking., Results: Medical records were reviewed from 234 children and adolescents with IBD treated with infliximab or adalimumab who underwent therapeutic drug monitoring (626 tests). All patients who had detectable antibodies were further analyzed. A total 58 patients (24.8%) developed ADA while being treated with infliximab or adalimumab. The incidence of antibody development was 12.9 per 100 person-years of anti-TNF treatment. Twenty-eight patients underwent dose optimization and 54% had undetectable ADA on follow-up monitoring. The mean duration of antibody suppression was 16.8 ± 10.9 months in those who were successfully suppressed with optimization. Patients who switched to a second anti-TNF medication were not more likely to develop antibodies to the second agent., Conclusions: With limited therapies for IBD and the chronicity of the disease, we advocate salvage of the current anti-TNF through dose optimization in pediatric patients with antibody level <10 U/mL.

Background: Loss of response in pediatric inflammatory bowel disease patients treated with biologic medications can be due to development of anti-drug antibodies. Natural history of anti-drug antibodies development has not been well described in pediatric inflammatory bowel disease. The primary aim of this study was to describe a single-center experience for the temporal onset of anti-drug antibodies detection., Methods: We performed a retrospective, single-center chart review of pediatric inflammatory bowel disease patients at the Division of Pediatric Gastroenterology, Hepatology, and Nutrition at Rainbow Babies and Children's Hospital from 2010 to 2015. Patients were treated with infliximab or adalimumab and had at least two evaluations for anti-drug antibodies with the homogenous mobility shift assay. Demographics, laboratory and medication data, and clinical disease activity were collected., Results: A total of 75 subjects are included in the analysis. Eighty-one percent of subjects were treated with infliximab. Eleven subjects developed anti-drug antibodies; average time to anti-drug antibodies detection was 13.2 ± 7.3 months. Longer duration of inflammatory bowel disease, L1 location in Crohn's disease, and not having immunomodulatory therapy before biologic was associated with higher risk of antibody detection. Antibody detection occurred more frequently with infliximab vs. adalimumab. Time-to-antibody detection for infliximab and adalimumab was 14.83 and 23.48 months, respectively., Conclusion: Chances of anti-drug antibodies detection in the infliximab group were higher than the adalimumab group. Time-to-antibody detection was 8.65 months longer in patients who received adalimumab when compared to infliximab. These results may have implications for long-term therapy and help guide use of concomitant immunomodulators.

Background & Aims: Proactive monitoring of drug trough concentrations and antibodies against drugs might help determine whether patients are likely to respond to treatment and increase efficacy. We investigated whether proactive drug monitoring is associated with higher rates of clinical remission in pediatric patients with Crohn's disease (CD)., Methods: We performed a nonblinded, randomized controlled trial of 78 children with CD (6-18 years old; 29% female; mean age, 14.3 ± 2.6 years) who had not received prior treatment with a biologic agent but had responded to adalimumab induction therapy, under scheduled monitoring of clinical and biologic measures (based on clinical factors and levels of C-reactive protein and fecal calprotectin), at pediatric gastroenterology units in Israel from July 2015 through December 2018. The patients were randomly assigned to groups that received proactive monitoring (trough concentrations measured at weeks 4 and 8 and then every 8 weeks until week 72, n = 38) or reactive monitoring (physicians were informed of trough concentrations after loss of response, n = 40). In both groups, doses and intervals of adalimumab were adjusted to achieve trough concentrations of 5 μg/mL. The primary endpoint was sustained corticosteroid-free clinical remission at all visits (week 8 through week 72)., Results: The primary endpoint was achieved by 31 children (82%) in the proactive group and 19 children (48%) in the reactive group (P = .002). Sixteen patients in the proactive monitoring group (42%) achieved a composite outcome of sustained corticosteroid-free remission, C-reactive protein ≤0.5 mg/dL, and level of fecal calprotectin ≤150 μg/g compared with 5 patients in the reactive monitoring group (12%) (P = .003). By week 72 of treatment, 33 patients in the proactive monitoring group had received adalimumab intensification (87%) compared with 24 patients in the reactive monitoring group (60%) (P = .001)., Conclusions: In a randomized controlled trial of pediatric patients with CD, we found that proactive monitoring of adalimumab trough concentrations and adjustment of doses and intervals resulted in significantly higher rates corticosteroid-free clinical remission than reactive monitoring (measuring trough concentration after loss of response). Clinicaltrials.gov no.: NCT02256462., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

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., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objectives: To compare different methods of antidrug antibody (ADA) against adalimumab detection in ankylosing spondylitis (AS) patients and the impact of ADA on adalimumab drug levels and mean ASDAS-CRP., Methods: We used the acid-dissociation-radioimmunoassay (ARIA), antidrug-binding-test (ABT) and a bridging Enzyme-linked Immunosorbent Assay (ELISA) to detect ADA at 4, 12 and 24 weeks of treatment. Patients were divided into groups; all assays negative (All-neg), only ARIA positive (ARIA-only-pos), ARIA and ABT positive, bridging ELISA negative (ARIA/ABT-double-pos) and all assays positive (All-pos)., Results: Eighty-three consecutive AS patient were included. At week 4, 18% compared to 11% and 0% of the patients tested positive for ADA in the ARIA, ABT and bridging ELISA, respectively. At week 12 and 24, cumulative 52% and 69% patients tested positive in the ARIA, compared to 27% and 30% patients in the ABT and 2% patients in the bridging ELISA. Adalimumab levels between All-neg and ARIA-only-pos were 9.1 (5.5-12.5) and 8.5 (5.7-12.3). Drug levels differed between ARIA/ABT-double-pos (2.7 (1.3-4.4)) and All-neg (9.1 (5.5-12.5)). All-pos patients had undetectable drug levels. Mean ASDAS-CRP at week 24 differs between All-neg (1.9 (±1.2)), and All-pos (3.8 (±1.9)) and ARIA/ABT-double-pos (2.0 (±1.1)) and All-pos., Conclusions: The majority of AS patients had detectable ADA against adalimumab in the ARIA. The ARIA detects more ADA compared to the less drug tolerant ABT and bridging ELISA. The clinical relevance depends on the impact on the bio-availability of the drug. A drug level measurement therefore helps to interpret ADA data regardless of type of assay used.

The immunogenicity of protein aggregates has been investigated in numerous studies. Nevertheless, it is still unknown which kind of protein aggregates enhance immunogenicity the most. The ability of the currently used in vitro and in vivo systems regarding their predictability of immunogenicity in humans is often questionable, and results are partially contradictive. In this study, we used a 2D in vitro assay and a complex 3D human artificial lymph node model to predict the immunogenicity of protein aggregates of bevacizumab and adalimumab. The monoclonal antibodies were exposed to different stress conditions such as light, heat, and mechanical stress to trigger the formation of protein aggregates and particles, and samples were analyzed thoroughly. Cells and culture supernatants were harvested and analyzed for dendritic cell marker and cytokines. Our study in the artificial lymph node model revealed that bevacizumab after exposure to heat triggered a TH1- and proinflammatory immune response, whereas no trend of immune responses was seen for adalimumab after exposure to different stress conditions. The human artificial lymph node model represents a new test model for testing the immunogenicity of protein aggregates combining the relevance of a 3D human system with the rather easy handling of an in vitro setup., (Copyright © 2019 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Rapid and versatile methods are needed for evaluation of immunogenicity in early safety studies. The present work presents a generic, simple and easy to use sandwich enzyme-linked immunosorbent assay for quasi-quantitative measurement of circulating immune complexes (CICs) formed by anti-drug antibodies (ADAs) in complex with human IgG in mouse plasma. The assay is suitable for evaluating the presence of in vivo formed CICs in mice exposed to human IgG antibodies independent of target and IgG subtype. The assay is established using commercially available antibodies, and calibrated using CIC mimics based on bis(sulfosuccinimidyl)suberate conjugated human and mouse IgG. The development and qualification process of the generic methodology is described and include acceptance criteria, stability, sensitivity, drug tolerance, spike recovery, precision and cut point determination. In order to demonstrate assay performance, its use is exemplified by quantifying CICs in mice administered with a fully human anti-TNF-α IgG 1 antibody (adalimumab) or a humanized anti-trinitrophenol (TNP) IgG 4 antibody. Results show a well-qualified reproducible assay set-up with adequate sensitivity, easy discrimination between positive and negatives and quasi-quantitative measurement of ADA-human IgG CICs in mice administered with each of two different human/humanized IgG antibodies., (Copyright © 2019 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.)

Objectives: To evaluate the incidence of anti-drug antibody (ADA) occurrences and ADA-related risk factors under adalimumab and infliximab treatment in rheumatoid arthritis (RA) patients., Methods: The study combined retrospective cohorts from the ABIRISK project totaling 366 RA patients treated with adalimumab (n = 240) or infliximab (n = 126), 92.4% of them anti-TNF naive (n = 328/355) and 96.6% of them co-treated with methotrexate (n = 341/353) with up to 18 months follow-up. ADA positivity was measured by enzyme-linked immunosorbent assay. The cumulative incidence of ADA was estimated, and potential bio-clinical factors were investigated using a Cox regression model on interval-censored data., Results: ADAs were detected within 18 months in 19.2% (n = 46) of the adalimumab-treated patients and 29.4% (n = 37) of the infliximab-treated patients. The cumulative incidence of ADA increased over time. In the adalimumab and infliximab groups, respectively, the incidence was 15.4% (5.2-20.2) and 0% (0-5.9) at 3 months, 17.6% (11.4-26.4) and 0% (0-25.9) at 6 months, 17.7% (12.6-37.5) and 34.1% (11.4-46.3) at 12 months, 50.0% (25.9-87.5) and 37.5% (25.9-77.4) at 15 months and 50.0% (25.9-87.5) and 66.7% (37.7-100) at 18 months. Factors associated with a higher risk of ADA development were: longer disease duration (1-3 vs. < 1 year; adalimumab: HR 3.0, 95% CI 1.0-8.7; infliximab: HR 2.7, 95% CI 1.1-6.8), moderate disease activity (DAS28 3.2-5.1 vs. < 3.2; adalimumab: HR 6.6, 95% CI 1.3-33.7) and lifetime smoking (infliximab: HR 2.7, 95% CI 1.2-6.3)., Conclusions: The current study focusing on patients co-treated with methotrexate for more than 95% of them found a late occurrence of ADAs not previously observed, whereby the risk continued to increase over 18 months. Disease duration, DAS28 and lifetime smoking are clinical predictors of ADA development., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Our aim was to assess the relationship between serum adalimumab levels, anti-drug antibodies (ADA) and disease activity in patients with axial spondylarthritis (SpA). We have carried out a single-centre cross-sectional study. adalimumab and ADA levels were analysed with ELISA and correlated with SpA activity using BASDAI and ASDAS scores. Adalimumab cut-off value was calculated to discriminate inactive disease/low disease activity (BASDAI < 4; ASDAS < 2.1) from moderate/high disease activity (BASDAI ≥ 4; ASDAS ≥ 2.1), using a receiver operating characteristic (ROC) curve. Up to January 2016, 51 consecutive patients were included. The median (range) age was 46.6 (18-68) and 47.1% were women. ADA prevalence was 27.5%, with none detected in the 21.6% receiving concomitant disease-modifying antirheumatic drugs (DMARDs) (p = 0.021). Adalimumab level was normal (> 3 mg/l) in 36 patients (70.6%), all without ADA. Fifteen patients (29.4%) had subtherapeutic adalimumab levels (< 3 mg/l), with ADA in 14 (93%). Median adalimumab (mg/l) was significantly higher in patients with inactive disease/low disease activity: BASDAI < 4 vs ≥ 4: 9.5 vs 2.6 (p < 0.01); ASDAS-CRP < 2.1 vs ≥ 2.1: 9.3 vs 0.3 (p < 0.001); ASDAS-ESR < 2.1 vs ≥ 2.1: 9.9 vs 3.0 (p < 0.001), and this finding was consistent with the result of the multivariate model. Patients with inactive disease/low disease activity presented significantly lower ADA levels. The adalimumab level cut-offs and area under the curve (AUC) obtained in the ROC curves were: ASDAS-CRP (< 2.1) 4.6 mg/l (AUC 81.2%; 95% CI 67.5-94.9; p < 0.001); ASDAS-ESR (< 2.1) 7.7 mg/l (AUC 82.4%; 95% CI 69.3-95.5; p < 0.001); BASDAI (< 4) 6.4 mg/l (AUC 73.5%; 95% CI 58.6-88.3; p < 0.01). In conclusion, presence of ADA in axial SpA patients treated with adalimumab was associated with lower serum drug levels. ADA levels were lower and adalimumab levels were higher in patients with inactive disease/low disease activity based on BASDAI and ASDAS indices. Concomitant treatment with MTX reduces de likelihood of finding ADA. Serum adalimumab levels above 4.6 mg/l are recommended to avoid compromising efficacy.