Anti-drug Antibody Concentrations Research Articles

Interference from anti-drug antibodies on the quantification of insulin: a comparison of an LC-MS/MS assay and immunoassays.

Aim: This study aims to compare the anti-drug antibody (ADA) interference in four pharmacokinetic (PK) assays across different platforms (AlphaLISA, Gyrolab, LC-MS/MS) and to devise a strategy for ADA interference mitigation to improve the accuracy of measured drug in total PK assays.Materials & methods: Spiked test samples, created to achieve different ADA concentrations in human serum also containing an insulin analogue, were analyzed alongside pooled clinical samples using four assays.Results & conclusion: Interference was observed in all platforms. A novel approach using the Gyrolab mixing CD, including acid dissociation in the PK assay, significantly reduced interference and thereby improved relative error from >99% to ≤20% yielding measurements well within the acceptance criteria. Clinical sample results reinforced findings from the test samples.

Population Pharmacokinetics of Adalimumab in Juvenile Idiopathic Arthritis Patients: A Retrospective Cohort Study Using Clinical Care Data.

Juvenile idiopathic arthritis (JIA) is a chronic autoimmune disorder that primarily affects the joints in children. Notably, it is known to co-occur with uveitis. Adalimumab, a monoclonal anti-TNF antibody, is effective in treating both conditions. A deeper understanding of the pharmacokinetics (PK) of adalimumab in JIA is crucial to advance in more personalized treatment approaches. The objective of this study is to evaluate the population PK profile of adalimumab in JIA and to explain causes for its variability. Adalimumab and antidrug antibody concentrations were retrospectively retrieved from the charts of patients with JIA. Initially, five literature-based population PK models of adalimumab were evaluated to assess their ability to describe the observed concentration-time profiles in the JIA cohort. These models included one specifically for the pediatric Crohn's disease population and four derived from studies in adult populations in healthy subjects and rheumatoid arthritis patients. Subsequently, a novel population PK model tailored to the JIA population was developed using NONMEM software. Monte Carlo simulations were then conducted utilizing the final PK model to visualize the concentration-time profile of adalimumab in patients with JIA and the impact of covariates. A cohort of 50 patients with JIA with 78 available adalimumab samples was assessed. The mean age was 11.8±3.9years, with a median body weight of 49kg (interquartile range 29.4-59.8kg). All literature models adequately described the concentration-time profiles in JIA. The best model, which was developed in patients with rheumatoid arthritis during the maintenance phase of treatment, served as a basis for estimating clearance in JIA, resulting in a value of 0.37L per day per 70kg. Patient body weight, antidrug antibodies, methotrexate use, CRP level, and comorbidity of uveitis were found to have a significant impact on adalimumab clearance, and these reduced the inter-patient variability from 58.6 to 28.0%. On steady state in the simulated patient population, the mean trough level was 7.4±5.5mg/L. The two dosing regimens of 20 and 40mg every other week, based on patients' body weight, resulted in comparable simulated overall drug exposure. Five literature models effectively described adalimumab PK in this pediatric cohort, highlighting the potential for extrapolating existing models to the pediatric population. The new JIA model confirmed the effect of several known covariates and found a novel association for drug clearance with methotrexate use (lower) and uveitis (higher), which might have clinical relevance for personalized dosing in JIA.

Evaluation of the Homogenous Mobility Shift Assay for Infliximab and Adalimumab Anti-drug Antibody Detection in the Clinical Laboratory.

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. 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. 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. 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.

P897 The association of HLA-DQA1*05 carriage with immunogenicity to anti-tumour necrosis factor therapy and drug persistence in Asian patients with inflammatory bowel disease

Abstract Background HLA-DQA1*05 carriage increases anti-tumour necrosis factor (TNF) immunogenicity and lowers drug persistence in European inflammatory bowel disease (IBD) patients. There is a paucity of data for Asian patients. We hypothesize that the HLA-DQA1*05 allele is present in our local IBD population and may be associated with similar clinical and pharmacokinetic outcomes as European cohorts. Methods A single-centre retrospective study of consecutive IBD patients on Infliximab (IFX) or Adalimumab (ADM) was performed. HLA-DQA1*05 carriage was tested with Sanger sequencing. Serum anti-drug antibody (ADA) levels were analysed at each IFX infusion and per physician discretion for ADM. Concomitant immunomodulator (IM) therapy with Azathioprine or Methotrexate was recorded. Primary outcome was immunogenicity to IFX or ADM, defined as ADA concentration ≥10 AU/ml at any time point. Secondary outcomes were loss of response (LOR), defined as IBD symptom-related treatment intensification, and persistence, defined as anti-TNF continuation at end of follow-up. The effects of HLA-DQA1*05 carriage on outcomes and predictors of persistence were analysed. Results 39 patients (28 Crohn’s disease, 11 ulcerative colitis) were included (mean age 39 years, median disease duration 10 years). 24 patients had IFX as first anti-TNF agent (21 with IM, 3 as monotherapy), 7 of whom had second-line ADM with IM. 15 patients had ADM as first anti-TNF agent (13 with IM, 2 as monotherapy), 2 of whom had second-line IFX (1 with IM). 15/39 (38.5%) patients were positive for HLA-DQA1*05. 42/48 (87.5%) of anti-TNF exposures were on IM. In HLA-DQA1*05 carriers compared to non-carriers, development of ADA (61.1% vs 47.8%, p=0.397) and LOR (42.1% vs 31.0%, p=0.433) was numerically higher but not statistically different. Persistence of first anti-TNF agent was similar between carriers and non-carriers at the end of follow-up (median 28.0 months vs 21.5 months, p=0.364) (Figure 1). ADA development was not associated with LOR (p=0.07) or persistence (p=0.29). 19/48 (39.6%) of anti-TNF exposures discontinued treatment at the end of follow-up, 13 of whom experienced LOR. 10/13 (76.9%) of patients with LOR were female. Female sex was significantly associated with anti-TNF non-persistence on univariable (OR 4.82, 95% CI 1.38-16.75, p=0.01) and multivariable logistic regression (OR 7.24, 95% CI 1.35-38.90, p=0.02), after adjusting for HLADQA1*05 carriage, presence of ADA and anti-TNF order (first versus second-line) (Table 1). Conclusion In Asian IBD patients, HLA-DQA1*05 carriage may not affect immunogenicity nor treatment persistence, especially with proactive therapeutic drug monitoring and concurrent IM. Female sex negatively affects persistence. Larger prospective studies are needed.

Efficacy and Safety of Biosimilar QL1207 vs. the Reference Aflibercept for Patients with Neovascular Age-Related Macular Degeneration: A Randomized Phase 3 Trial.

This trial aimed to compare the efficacy and safety between biosimilar QL1207 and the reference aflibercept for the treatment of neovascular age-related macular degeneration (nAMD). This randomized, double-blind, phase 3 trial was conducted at 35 centers in China. Patients aged ≥ 50years old with untreated subfoveal choroidal neovascularization secondary to nAMD and best-corrected visual acuity (BCVA) letter score of 73-34 were eligible. Patients were randomly assigned to receive intravitreous injections of QL1207 or aflibercept 2mg (0.05ml) in the study eye every 4weeks for the first 3months, followed by 2mg every 8weeks until week 48, stratified by baseline BCVA ≥ or < 45 letters. The primary endpoint was BCVA change from baseline at week 12. The equivalence margin was ± 5 letters. The safety, immunogenicity, pharmacokinetics (PK), and plasma vascular endothelial growth factor (VEGF) concentration were also evaluated. A total of 366 patients were enrolled (QL1207 group, n = 185; aflibercept group, n = 181) from Aug 2019 to Jan 2022 with comparable baseline characteristics. The least-squares mean difference in BCVA changeswas - 1.1 letters(95% confidence interval - 3.0 to 0.7; P = 0.2275) between the two groups, within the equivalence margin. The incidences of treatment-emergent adverse events (TEAE; QL1207: 71.4% [132/185] vs. aflibercept: 71.8% [130/181]) and serious TEAE (QL1207: 14.1% [26] vs. aflibercept: 12.7% [23]) appeared comparable between treatment groups, and no new safety signal was found. Anti-drug antibody, PK profiles, and VEGF concentration were similar between the two groups. QL1207 has equivalent efficacy to aflibercept for nAMD with similar safety profiles. It could be used as an alternative anti-VEGF agent for clinical practice. ClinicalTrials.gov: NCT05345236 (retrospectively registered on April 25, 2022); National Medical Products Administration of China: CTR20190937 (May 20, 2019).

Development and validation of enzyme-linked immunosorbent assays for the measurement of infliximab and anti-drug antibody levels

Infliximab and its anti-drug antibody (ADA) serum concentrations exhibit a strong correlation with clinical response and loss of response. The use of therapeutic drug monitoring to measure the concentration of infliximab and ADA can facilitate clinical decision-making, helping patients attain optimal therapeutic effects. However, there are still limitations to the existing infliximab and its ADA detection methods. Therefore, this study aimed to develop and validate enzyme-linked immunosorbent assay (ELISA)-based methods for measuring infliximab and its ADA levels in human plasma according to the general recommendations for immunoassays. Free infliximab is bound by recombinant TNF-α and detected using HRP-labeled anti-human antibody. The ADA is captured by on-plate-coated infliximab and recognized by biotin-labeled infliximab. Two bridging ELISA assays were developed and after assay optimization and validation, these assays have been applied in ten patients with inflammatory bowel disease (IBD). In infliximab detection assay, a standard curve ranging from 0.10 μg/mL to 8.0 μg/mL with great precision and accuracy has been established. Drug tolerance of the ADA assay was that 100 ng/mL ADA could tolerate at least 5.0 μg/mL infliximab in the plasma using a commercially available monoclonal anti-infliximab antibody as the positive control. The ADA screening and confirmatory assays achieved a sensitivity of 36.74 ng/mL and 37.15 ng/mL, respectively. All other assay characteristics met the requirements. The mean concentration of infliximab in eight patients with IBD was 7.88 (1.87–21.1) μg/mL, and the ADA levels were all negative. Moreover, the concentrations of infliximab in the remaining two patients were below the LLOQ and the ADAs were positive. Thus, accurate and sensitive ELISA methods have been developed and validated for the detection of infliximab and its ADA concentrations and have been successfully applied to clinical therapeutic drug monitoring.

Reduced Graphene Oxide Electrolyte-Gated Transistor Immunosensor with Highly Selective Multiparametric Detection of Anti-Drug Antibodies.

The advent of immunotherapies with biological drugs has revolutionized the treatment of cancers and auto-immune diseases. However, in some patients the production of anti-drug antibodies (ADAs) hampers the drug efficacy. The concentration of ADAs is typically in the range of 1-10 pM, hence their immunodetection is challenging. We focus here on ADAs towards Infliximab (IFX), a drug used to treat rheumatoid arthritis and other auto-immune diseases. We report an ambipolar electrolyte-gated transistor (EGT) immunosensor based on reduced graphene oxide (rGO) channel and IFX bound to the gate electrode as the specific probe. The rGO-EGTs are easy to fabricate, exhibit low voltage operations (≤ 0.3V), a robust response within 15min, and ultra-high sensitivity (10 aM limit of detection). We propose a multiparametric analysis of the whole rGO-EGT transfer curves based on the type-I generalized extreme value distribution. We demonstrate that it allows us to selectively quantify ADAs also in the co-presence of its antagonist tumour necrosis factor alpha (TNF-α), the natural circulating target of IFX. This article is protected by copyright. All rights reserved.

Optimization of a Quantitative Anti-Drug Antibodies against Infliximab Assay with the Liquid Chromatography-Tandem Mass Spectrometry: A Method Validation Study and Future Perspectives.

Monoclonal antibodies (mAbs), such as infliximab, are important treatment options for different diseases. Immunogenicity is a major risk, resulting in anti-drug antibodies (ADAs), being associated with adverse events and loss of response, influencing long-term outcomes. The development of ADAs against infliximab is primarily measured by immunoassays like radioimmunoassay (RIA). Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) is increasingly utilized across different fields, this technique is currently not used for ADAs against infliximab measurements. Therefore, we developed the first LC-MS/MS method. Stable isotopically labeled infliximab antigen-binding fragments (SIL IFX F(ab')2) were used to bind and measure ADAs indirectly. Protein A magnetic beads were used to capture IgG, including ADAs, whereafter SIL IFX F(ab')2 was added for labeling. After washing, internal standard addition, elution, denaturation and digestion samples were measured by LC-MS/MS. Internal validation showed good linearity between 0.1 and 16 mg/L (R2 > 0.998). Sixty samples were used for cross-validation with RIA, and no significant difference between ADA concentrations was found. The methods had high correlation (R = 0.94, p < 0.001) and excellent agreement, intraclass correlation coefficient = 0.912 (95% confidence interval 0.858-0.947, p < 0.001). We present the first ADA against the infliximab LC-MS/MS method. The method is amendable for quantifying other ADAs, making it applicable as a template for future ADA methods.

Measuring Serum Vedolizumab and Vedolizumab Antibodies: Comparison of Commercial Assays with the Vedolizumab Clinical Development Assay.

Vedolizumab (VDZ) is an anti-α 4 β 7 integrin monoclonal antibody approved for inflammatory bowel disease treatment. VDZ serum and antidrug antibody (ADA) concentrations may be used for treatment optimization. In this article, the results of 5 commercial assays (Grifols, Immundiagnostik, Progenika, Sanquin, and Theradiag) measuring VDZ concentration and ADA were compared with those of the reference assays used in VDZ clinical studies. Our findings will assist clinicians in interpreting commercial assay results in the context of VDZ clinical trial data. VDZ-treated patient samples were used to evaluate the agreement between commercial assays and the reference VDZ serum concentration assay, based on linear regression, Bland-Altman, and qualitative agreement analyses. VDZ ADAs were detected using qualitative assays. Specificity, selectivity, accuracy, and precision were assessed using serum samples from healthy donors or patients with IBD (VDZ serum concentration <0.5 mcg/mL) spiked with VDZ, with/without other biologics (identical sample sets per assay). All assays were specific and selective for VDZ. Overall, the commercial assay results for VDZ-spiked samples correlated well with those of the reference serum concentration assay (R 2 ≥ 0.98). Compared with the Immundiagnostik and Theradiag assays, the Grifols, Sanquin, and Progenika assays had the best reference assay agreement (based on regression analysis, Bland-Altman plots, and qualitative agreement [Cohen's kappa ≥0.92]). All immunogenicity assays detected VDZ ADAs; only the reference assay detected VDZ ADAs in the presence of 15 mcg/mL VDZ, advising caution with commercial ADA assays if VDZ is present. All 5 commercial assays are suitable for VDZ therapeutic monitoring and ADA testing. However, the absolute values from the reference assays and the different commercial assays were not comparable, indicating that the same assay must be used for repeated monitoring of VDZ serum concentrations.

In dogs diagnosed with osteoarthritis, how safe and effective is long-term treatment with bedinvetmab in providing analgesia?

PICO question In dogs diagnosed with osteoarthritis (OA), how safe is treatment with bedinvetmab, when compared to a placebo and how effective in long-term reduction of the severity of the clinical signs associated with OA-related pain? Clinical bottom line Category of research Treatment. Number and type of study designs reviewed Two papers were critically reviewed. One was a randomised, blinded, multi-arm laboratory safety study; the other a multi-center field trial consisting of a block-randomised, double blind, placebo-controlled phase, followed by a non-comparative, open-label case series study. Strength of evidence Weak. Outcomes reported One study rated the reduction of the severity of clinical signs associated with OA pain using owner Canine Brief Pain Inventory (CBPI) ratings and non-validated veterinary clinical assessments (VCAs). Safety was addressed by evaluating adverse health effects (AHEs), concentration of antidrug antibodies (ADAs), and clinical pathology. Significant improvements in pain scores and VCAs were reported in this treatment study. The second safety-only study used clinical observation to evaluate AHEs. Both studies reported AHEs. Conclusion A single study suggests that treatment with bedinvetmab is effective. Two studies support the drug having few AHEs. Both studies have significant design limitations preventing the evaluation of bedinvetmab effectiveness. There is weak / inconclusive evidence for long-term efficacy and short-term safety of OA treatment with bedinvetmab. The decision to use bedinvetmab remains dependent on the judgement and experience of the clinician. How to apply this evidence in practice The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources. Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.

A phase Ia dose-escalation trial of Ametumumab (a fully human monoclonal antibody against epidermal growth factor receptor) in patients with advanced solid malignancies.

Epidermal growth factor receptor (EGFR) is a well-known target for cancer treatment. However, the authorized anti-EGFR monoclonal antibodies generally cause several toxic effects, especially severe cutaneous toxicities as well as infusion reactions, and the clinical indications are limited. Here we developed Ametumumab, a fully human recombinant anti-EGFR monoclonal antibody. To assess the safety, tolerability, pharmacokinetics (PK), and immunogenicity of Ametumumab. A first-in-human phase Ia dose escalation study of Ametumumab in patients with advanced solid malignancies. An open-label, first-in-human dose escalation study was done in 22 patients with advanced malignancies who received six ascending dosages ranging from 75 to 750 mg/m2. Following a single dosage and a 28-day dose-limiting toxicity (DLT) monitoring period, patients were given repeated doses weekly. Blood samples were taken to determine the PK parameters of Ametumumab and anti-drug antibody concentrations. Every 8 weeks, radiographic tumor evaluations were conducted. In this trial, no DLT was observed, and the maximum tolerated dose was not reached at doses up to 750 mg/m2. There were no severe adverse events but mild and moderate adverse effects, such as headache, proteinuria, and rash. Single-dose PK results demonstrated a straightforward linear relationship with dosage escalation. The medication concentrations accumulated and attained steady-state after four rounds of injections. It was calculated that 10 patients with disease control would be observed in the 22 evaluable patients. The disease control rate was 45.5%. The Ametumumab was well tolerated and safe in patients with advanced solid malignancies, exhibiting minimal immunogenicity, a long half-life, high levels of drug exposure in the blood, and preliminary effectiveness. The trial was registered with CTR20170343 on 10 April 2017, The China Center for Drug Evaluation.

Determination of Anti-drug Antibody Affinity in Clinical Study Samples Provides a Tool for Evaluation of Immune Response Maturation

Characterization of clinical anti-drug antibody (ADA) responses to biotherapeutics can be important to understanding the consequences of immunogenicity. ADA are expected to be polyclonal, with composition and affinities that evolve over time. Measuring ADA binding affinity can be complicated by the polyclonal nature of response, residual drug in sample, and low ADA levels. We developed a novel workflow to determine the apparent ADA affinity (KD) against a monoclonal antibody biotherapeutic, PF-06480605. An affinity capture elution pre-treatment step was used to isolate ADA and remove residual drug interference from samples. Solution-phase equilibrium incubation was performed using drug and sample ADA as variable and fixed binding interactants, respectively. Unbound ADA concentration was measured using a Singulex Erenna ligand-binding assay (LBA) method. Apparent ADA KD values were calculated using a custom R Shiny algorithm. KD values determined for ADA positive samples showed good correlation with other immunogenicity parameters, including titers and neutralizing antibody (NAb) activity with a general increase in affinity over time, indicative of a maturing immune response. Time of onset of high affinity responses (KD < 100 pM) varied between patients, ranging from 16 to 24 weeks. Antibody responses appeared monophasic at earlier time points, trending towards a biphasic response with a variable transition time and general increase in proportion of high affinity ADA over time. Herein, we provide a novel, sensitive bioanalytical method to determine the KD of ADA in clinical samples. The observed decrease in ADA KD is consistent with evidence of a maturing immune response.Graphical

Intérêt du suivi immunologique des biothérapies anti-TNF

AbstractUtility of therapeutic drug monitoring of anti-TNF biologicsDespite a good clinical efficacy, treatments targeting the tumor necrosis factor alpha (anti-TNF) are frequently confronted with primary non-response or secondary loss of response most often due to a poor choice of the therapeutic target, a suboptimal dosing of the drug or the appearance of anti-drug antibodies (ADAbs). In order to help the clinician in managing these primary or secondary resistances, algorithms have been developed based on therapeutic drug monitoring (TDM) with measurement of the serum trough concentration and detection of anti-drug antibodies. The reactive use of these algorithms during a disease flare allows restoration of the therapeutic efficacy at a lower cost compared to an empirical optimization approach. However, the clinical benefit remains more controversial, as well as the proactive use of TDM in order to prevent relapses by maintaining the serum concentration of the biologic within a therapeutic range. Despite these limitations, TDM of anti-TNF is now proposed in several international guidelines, particularly for the management of inflammatory bowel disease.

Therapeutic drug monitoring in inflammatory bowel disease treatments.

Recently, biological drugs have played a leading role in the treatment of inflammatory bowel disease, and therapeutic drug monitoring (TDM) may be useful in maximizing their effectiveness. TDM involves the measurement of serum drug and anti-drug antibodies concentrations as the basis for dosage adjustments or drug conversions to achieve a higher response rate. We believe that concentration thresholds should be individualized based on patients’ disease severity, extent and phenotype, and therapeutic purposes should also be considered, with higher cut-offs mainly needed for endoscopic and fistula healing than for symptomatic remission. Proactive and reactive TDM can help optimize treatment, especially in patients receiving anti-tumour necrosis factor, and guide dose adjustment or drug conversion with lower cost. TDM is a promising approach to achieve precision medicine and targeted medicine in the future.

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.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12325-022-02064-x.

P184 Relationship Between Patient Sex and Serum Tumor Necrosis Factor Antagonist Drug and Anti-Drug Antibody Concentrations in Inflammatory Bowel Disease; A Nationwide Cohort Study

Abstract Background Anti-drug antibodies to infliximab (ATI) and adalimumab (ATA) are associated with loss of response to tumor necrosis factor antagonist (anti-TNF) therapy in inflammatory bowel disease (IBD). We evaluated the relationship between patient sex and serum TNF antagonist drug and antibody concentrations in inflammatory bowel disease Methods A nationwide multicenter retrospective cohort study was conducted by evaluating patients’ charts from July 2018 until September 2021. The effect of patient sex on anti-drug antibodies and serum drug concentration in patients with IBD across 7 hospitals was investigated. A subgroup analysis also investigated the effect of anti-TNF combination therapy. Geometric means were calculated, and multiple linear regression was used to estimate the adjusted ratio of geometric means (RoGM) and their 95% confidence intervals (CI). Results In the total study sample (n = 1093), males receiving infliximab had higher anti-drug antibody concentrations (38.3 vs. 22.3 AU/ml; aRoGM = 1.72, 95% CI: 1.30–2.27, p-value &amp;lt;0.001) compared to females. Additionally, infliximab serum drug concentrations among males were lower compared to females (2.6 vs. 4.1 ug/ml; aRoGM = 0.62, 95% CI: 0.44–0.88, p-value = 0.007). In the subgroup analysis (n = 359), male compared to female patients on combination therapy with infliximab and immunomodulators had similar anti-drug antibody concentrations (30.2 vs. 21.9 AU/ml; aRoGM = 1.38, 95% CI: 0.79–2.40, p-value = 0.254). There was no difference in the anti-drug antibody and serum drug concentrations among males and females on adalimumab. Conclusion In patients receiving infliximab, anti-drug antibodies were higher in males than females. Consistent with this, serum drug concentrations were lower in males than females on infliximab. There was no difference in anti-drug antibody and serum drug concentrations among males and females on adalimumab. In addition, no difference in anti-drug antibodies between males and females receiving anti-TNF combination therapy was observed

P395 Proactive Therapeutic Drug Monitoring May Reduce the Need for Combination Therapy in Inflammatory Bowel Disease Patients Treated with Infliximab

Abstract Background Combination therapy with an immunomodulator [IM] is recommended by ECCO guidelines for patients with moderate-to-severe inflammatory bowel disease (IBD) treated with infliximab [IFX]. Combination therapy reduce anti-drug antibody (ATI) formation. Maintenance of adequate trough IFX levels is also known to reduce ATI formation. Methods We hypothesised that the use of proactive TDM in patients receiving IFX monotherapy would result in equivalent therapy outcomes compared with patients receiving IFX in combination with an immunomodulator. A pilot study using proactive TDM was undertaken at our unit with IFX and ATI levels, assessed at trough, in all IBD patients receiving IFX. We retrospectively evaluated the outcome of proactive IFX TDM on IFX therapy outcome. Baseline demographics, IFX dosing schedules and use of concomitant immunomodulators were documented. The study primary endpoint was time to infliximab discontinuation in IFX monotherapy and combination therapy groups. Results 109 IBD patients receiving IFX with proactive TDM assessment were included. Median age, 36 years, 46% were female and, 36% UC., 37% and, 67% of patients were receiving IFX combination and monotherapy respectively. There was no significant difference in mean time to drug discontinuation between IFX combination and monotherapy groups, 2.33 [95% CI, 2.2–2.5] versus, 2.32 [95% CI, 2.0 –, 2.6] years respectively, p = 0.63. ATI concentrations [median] did not differ significantly between IFX combination and monotherapy groups, 2.9 AU/mL versus, 11.6 AU/mL, p = 0.54. In a multivariate analysis disease activity [p=0.005], low IFX levels [p=0.01] and elevated ATIs [p=0.001] were all independently associated with IFX discontinuation. There was no association between the use of IFX combination therapy and rates of IFX discontinuation, p=0.42. Conclusion Infliximab persistence, which is a proxy for successful therapy outcome, was similar in IFX monotherapy and combination therapy groups when proactive TDM was utilised. In the absence of concomitant immunomodulatory therapy, proactive TDM may improve IFX monotherapy outcomes, by maintaining higher IFX concentrations.

Relationship Between Patient Sex and Serum Tumor Necrosis Factor Antagonist Drug and Anti-drug Antibody Concentrations in Inflammatory Bowel Disease; A Nationwide Cohort Study.

Background: Anti-drug antibodies to infliximab (ATI) and adalimumab (ATA) are associated with loss of response to tumor necrosis factor antagonist (anti-TNF) therapy in inflammatory bowel disease (IBD). We evaluated the relationship between patient sex and serum TNF antagonist drug and antibody concentrations in inflammatory bowel disease.Methods: A nationwide multicenter retrospective cohort study was conducted by evaluating patients' charts from July 2018 until September 2021. The effect of patient sex on anti-drug antibodies and serum drug concentration in patients with IBD across seven hospitals was investigated. A subgroup analysis also investigated the effect of anti-TNF combination therapy. Geometric means were calculated, and multiple linear regression was used to estimate the adjusted ratio of geometric means (RoGM) and their 95% confidence intervals (CI).Results: In the total study sample (n = 1093), males receiving infliximab had higher anti-drug antibody concentrations (38.3 vs. 22.3 AU/ml; aRoGM = 1.72, 95% CI: 1.30–2.27, p < 0.001) compared to females. Additionally, infliximab serum drug concentrations among males were lower compared to females (2.6 vs. 4.1 ug/ml; aRoGM = 0.62, 95% CI: 0.44–0.88, p = 0.007). In the subgroup analysis (n = 359), male compared to female patients on combination therapy with infliximab and immunomodulators had similar anti-drug antibody concentrations (30.2 vs. 21.9 AU/ml; aRoGM = 1.38, 95% CI: 0.79–2.40, p = 0.254). There was no difference in the anti-drug antibody and serum drug concentrations among males and females on adalimumab.Conclusion: In patients receiving infliximab, anti-drug antibodies were higher in males than females. Consistent with this, serum drug concentrations were lower in males than females on infliximab. There was no difference in anti-drug antibody and serum drug concentrations among males and females on adalimumab. In addition, no difference in anti-drug antibodies between males and females receiving anti-TNF combination therapy was observed.

Noninvasive Targeted Crohn Disease Management by Combining Endoscopic Healing Index and Therapeutic Drug Monitoring.

Therapeutic drug monitoring (TDM) with measurement of serum drug and antidrug antibody concentrations is used to optimize tumor necrosis factor antagonists (anti-TNF). The endoscopic healing index (EHI) is a validated serum-based assay to measure mucosal inflammation in adults with Crohn disease (CD). Our objectives were to evaluate the relationship between EHI and TDM results and to determine the anti-TNF concentration range associated with EHI <20 (consistent with endoscopic remission). Adult and pediatric patients with CD (N = 1731) were selected retrospectively from a clinical laboratory cohort. Patients were selected if they had an ICD-10 code for CD and if results for EHI and TDM were available within 30 days of each other. The relationship between EHI and TDM results was examined and the anti-TNF concentration range associated with EHI <20 vs >50 was evaluated. Median anti-TNF concentration was higher in patients with EHI <20 vs >50 for infliximab (N = 796): 11.1 vs 3.4 µg/mL and for adalimumab (N = 935): 9.2 vs 5.0 µg/mL (P < 0.0001 both drugs). Patients with antibodies to infliximab (12.8%) or adalimumab (14.9%) had lower anti-TNF concentrations (P < 0.001 both drugs) and higher EHI (P < 0.01 both drugs). The concentration range for infliximab: 5-15 µg/mL (5-9 µg/mL in pediatric patients) and for adalimumab: 5-10 µg/mL (8 µg/mL in pediatric patients) best discriminated EHI <20 vs >50. We report the anti-TNF concentration range associated with EHI <20. Combined testing of EHI and TDM is proposed as a noninvasive approach for treat-to-target management which could improve the ability to monitor disease and optimize anti-TNF therapy.

Albumin-to-Globulin Ratio at 1 Year after Anti-Tumor Necrosis Factor α Therapy Can Serve as a Prognostic Biomarker in Pediatric Crohn's Disease Patients.

Background/AimsThe efficacy of biologics for the treatment of Crohn’s disease (CD) is affected by the drug concentrations. We aimed to evaluate the importance of albumin and globulin which are known to be associated with drug concentrations as prognostic biomarkers in CD.MethodsIn total, 121 pediatric patients with CD who had received anti-tumor necrosis factor (TNF)-α therapy were retrospectively examined between January 2010 and February 2019.ResultsRelapse was observed in 48.8% of patients (59/121). The level of calprotectin (odds ratio, 2.13; p=0.03) and the albumin-to-globulin ratio (AGR) at 1 year after anti-TNF-α therapy (odds ratio, 0.0002; p=0.003) were associated with relapse. The AGR at 1 year after anti-TNF-α therapy was the only factor associated with the time-to-relapse (hazard ratio, 0.02; p<0.001). The optimal AGR cutoff value for the prediction of relapse was 1.47 (area under the curve, 0.916; p<0.001). The median infliximab trough level (TL) was lower in patients with AGRs <1.47 than in those with AGRs ≥1.47. Anti-drug antibody (ADA) concentrations were negatively correlated with the AGR at 1 year of anti-TNF-α therapy (r=–0.413, p=0.032).ConclusionsAGR can be used to predict relapse. Patients with AGRs <1.47 at 1 year after anti-TNF-α therapy are more likely to have low drug TLs and develop ADAs, which increase the possibility of relapse than those with AGRs ≥1.47. Therefore, if the AGR at 1 year after anti-TNF-α therapy is less than 1.47, clinicians should monitor disease activity, assess the TLs of the anti-TNF-α agents, test for ADAs and determine the appropriate therapeutic strategies.