Anti-infliximab Antibodies Research Articles

An in vitro comparison of four different immunoassays for the monitoring of Infliximab biosimilars drug levels

BackgroundSB2 (Renflexis®, Merck) and CT-P13 (Inflectra®, Pfizer) are biosimilars of the reference Infliximab (Remicade®, Janssen) and are approved in Canada for use in indications for which Infliximab is approved, including inflammatory bowel disease. These biosimilars are structurally different but exhibit comparable physicochemical characteristics, pharmaceutical effectiveness and immunogenicity compared to Infliximab. Optimal Infliximab therapy currently relies on therapeutic drug monitoring offered by several reference laboratories. ObjectiveBecause the appropriate dosing depends on accurate determination of drug levels and anti-drug antibodies, the ability of current Infliximab assays to measure the biosimilars and corresponding antibodies needs to be demonstrated. MethodsThe correlation between Infliximab and the biosimilars measured with four different enzyme-linked immunosorbent assays for Infliximab detection was evaluated. Spiked serum samples were assayed with kits from (A) Immunodiagnostik/ALPCO Diagnostics, (B) R-Biopharm, (C) Theradiag and (D) Progenika Biopharma. The impact of various concentrations of antibodies to Infliximab on the quantification of biosimilars was also tested. ResultsA good correlation of SB2, CT-P13 and reference Infliximab spiked serum samples was observed with the four assays. The observed bias between the original drug and biosimilars is clinically insignificant and less than the usual analytical variability observed with these methods. The quantification of the biosimilars and Infliximab was equally impacted in serums containing antibodies to Infliximab. The recovery of the drugs was inversely correlated with the concentration of anti-Infliximab antibodies, suggesting common immunodominant epitopes for SB2, CT-P13 and Infliximab. ConclusionThe ability of these assays to properly quantify the biosimilars Renflexis® and Inflectra® has been demonstrated. The therapeutic drug monitoring required for Infliximab therapy can be adequately performed with the biosimilars using the kits currently in use or available in clinical laboratories.

P693 Development and evaluation of i-TRACKER infliximab and i-TRACKER anti-Infliximab kits: fast and innovative chemiluminescent assays for the monitoring of patients treated with infliximab

Abstract Background Infliximab, a monoclonal antibody directed against TNFα, is a drug widely used for the treatment of inflammatory diseases (rheumatoid arthritis, Crohn’s disease, etc.). Therapeutic drug monitoring is currently proposed to provide useful information to clinicians to improve the efficacy of the treatment. Theradiag has just developed the innovative i-TRACKER Infliximab and i-TRACKER Anti-Infliximab kits: fast quantifications of Infliximab and Anti-Infliximab antibodies fully automated on the random access i-TRACK10 chemiluminescent analyser. Methods Analytical performances were assessed using two types of serum samples: human serum spiked with Infliximab or Anti-Infliximab antibodies, and samples from inflammatory bowel disease patients treated with Infliximab (n = 41). On one hand, Infliximab from serum sample was captured by TNFα coupled magnetic microparticles and Anti-Infliximab polyclonal antibodies conjugated to acridinium ester were used for the detection of Infliximab. On the other hand, Anti-Infliximab antibodies were captured according to Infliximab coupled magnetic microparticles and detected with the use of Infliximab conjugated to acridinium ester. Light emission was linked to the quantity of Infliximab, or anti-Infliximab antibodies, presents in the sample. Results Infliximab measurement showed high accuracy (recovery was comprised between 80% and 107%). High precisions were reached for both assays (intra-precision CV were below 8.1% and 2.7% for Infliximab and Anti-Infliximab assays; inter-precision CV were below 11.7% and 4.8% for Infliximab and Anti-Infliximab assays) and no interferences were seen with biologic agents (bilirubin, haemoglobin, lipids, biotin and rheumatoid factors). The dynamic ranges of the assays were 0.3–24 µg/ml for Infliximab quantification and 10–2000 ng/ml for Anti-Infliximab antibodies quantification. i-TRACKER Infliximab and i-TRACKER anti-Infliximab assays were compared with respective LISA-TRACKER assays and showed excellent correlation (R² = 0.94, Slope = 1.04 for Infliximab assay; Spearman’s coefficient correlation was 0.98 for Anti-Infliximab assay). Conclusion i-TRACKER kits are innovative assays which exhibit fast (time to results <40 min), accurate (standardised with NIBSC/WHO international standard Infliximab) and reproducible results for the quantification of princeps and biosimilar molecules (CT-P13, SB2). Excellent agreements were observed with respective LISA-TRACKER assays. i-TRACKER kits are valuable tools for the monitoring of patients treated with Infliximab.

P362 Prospective study of phArmaCokinetics of InFliximab during induction in patients with Crohn’s disease and ulcerative colitis (PACIFIC)

Abstract Background Loss of response (LOR) to infliximab (IFX) remains a challenge in routine management of IBD patients. We evaluated IFX high-resolution pharmacokinetics (PK) during induction with intermediate and peak PK levels. Methods This is a prospective, multicentre (n = 9), interventional study approved by EC (P2017/484). Fourteen blood samples were collected per patient from baseline to week 30. All patients were IFX naïve with active disease according to clinical, biological and endoscopy criteria. The primary outcome evaluated the inter-individual variability of IFX PK during induction and correlation with remission at week 30. In addition to trough levels (TLs), intermediate (ILs) and peak levels (PLs) were also measured and defined as drug level between two infusions and drug level early on after infusion (+2h), respectively. Remission was defined as having a Harvey Bradshaw Index (HBI) ≤ 4 and C-Reactive Protein (CRP) ≤5 for Crohn’s disease (CD), and as a clinical Mayo score ≤2 and faecal calprotectin <250 µg/g for ulcerative colitis (UC). IFX samples were measured by ELISA (Apdia) while a drug-tolerant affinity capture elution anti-infliximab assay was used to measure anti-infliximab antibodies (ATI) at weeks 6, 22 and 30. Results Demographic and baseline data of the study population are presented in Table 1. Among the 62 patients enrolled, 33.9% of patients (n = 21/62) were in remission at week 30. Eight patients dropped out due to disease worsening. Median TLs at week 6 were higher among patients in clinical remission at week 30 (p = 0.02) confirming previous observations. However, ILs at day 3 as well as PLs after the third infusion were also significantly higher in patients in clinical remission at week 30 (Figure 1a–c). ATI were detected as soon as week 6. At week 2, infliximab levels were significantly lower among patients in which ATI developed at a later time point (p = 0.006) and this observation was confirmed when measuring ILs at day 17 (p = 0.002), TLs at week 6 (p = 0.002) and ILs at week 10 (p = 0.001). Conclusion This multicentre prospective study demonstrates that intermediate levels as early as day 3 predict remission at week 30 in IBD patients. Low IFX levels during induction were correlated to future ATI development. PK modelling may allow to better select patients early on for sustained remission with infliximab.

Rapid test detection of anti-infliximab antibodies: performance comparison with three different immunoassays.

Background and Aims:Therapeutic drug monitoring (TDM) of infliximab (IFX) and anti-infliximab antibodies (ATIs) is essential for treatment optimisation in inflammatory bowel disease (IBD) patients. The aim of this study was to estimate and compare the agreement and accuracy between a new rapid test and three established enzyme-linked immunosorbent assays (ELISAs) to quantify ATIs levels, and to evaluate the impact of exogenous IFX on the performance of these assays.Methods:We analysed 200 serum samples from 57 IBD outpatients in IFX induction or maintenance therapy at six IBD centres in Portugal. ATI levels were quantified using the rapid test Quantum Blue® (QB) Anti-Infliximab (Bühlmann) and three established ELISAs: In-House, Theradiag (Lisa Tracker Anti-Infliximab), and Immundiagnostik (IDKmonitor Infliximab). ATIs were quantified in patients’ serum samples and spiked samples with exogenous IFX, based on analytical and clinical cutoffs. Qualitative agreement and accuracy were estimated by Cohen’s kappa (k) with 95% confidence intervals.Results:ATIs quantification with clinical cutoffs showed a slight agreement between QB rapid test and In-House [k = 0.163 (0.051–0.276)] and Immundiagnostik [k = 0.085 (0.000–0.177)]. Regarding IFX/ATIs status, the QB rapid test showed a substantial agreement with Theradiag [k = 0.808 (0.729–0.888)] and a fair agreement with In-House [k = 0.343 (0.254–0.431)] and Immundiagnostik [k = 0.217 (0.138–0.297)]. The QB rapid test could not detect ATI-positive levels in samples with exogenous IFX at 5–300 µg/ml. Interference on ATIs detection was observed at exogenous IFX ⩾30 µg/ml for In-house and Immundiagnostik assays.Conclusion:QB rapid test is only suitable to detect ATI-positive levels in the absence of IFX.

Patient-Led Remote Intracapillary Pharmacokinetic Sampling (Fingerpricks): Validation and Acceptability for Home Therapeutic Drug Monitoring in Patients with Ibd in the COVID-19 Pandemic

Background: During the first wave of the coronavirus (COVID-19) pandemic, restrictive public health measures including prolonged shielding, were recommended by the United Kingdom government for many patients with immune-mediated inflammatory disorders treated with immunosuppressive and biologic drugs. Low-volume intracapillary blood sampling can be undertaken by patients at home and returned by post and may ensure access to therapeutic drug monitoring (TDM) for all patients irrespective of shielding status.Methods: We undertook a cross-sectional blood sampling methods comparison study to assess the clinical validity and acceptability to patients of low volume intracapillary testing for serum TDM enzyme-linked immunosorbent assays (ELISA) compared to conventional venepuncture. Sample types were compared using linear regression and fit-for-purpose equivalence was defined using total allowable error (TEa) rates derived using interassay coefficient of variations from routine clinical practice. Acceptability was assessed using a purpose-designed questionnaire.Findings: The median (IQR) volume of serum obtained using intracapillary sampling was 195µL (130-210). We showed drug level equivalence (slope [95% CI]: TEa vs observed mean % difference) between intracapillary sampling and conventional venepuncture for adalimumab (1·02 [0·90-1·14]: 11·7% vs 2·1%), infliximab (1·08 [0·98-1·18]: 18·3% vs 1·2%), vedolizumab (0·91 [0·85-0·96]: 17·6% vs 4·1%), and ustekinumab (0·92 [0·90-0·94]: 19·4% vs 3·3%). Anti-drug antibody equivalence was observed for anti-adalimumab (0·96 [0·95-0·98]: 24·5% vs 2·1%) and anti-infliximab (0·89 [0·81-0·97]: 17·3% vs 1·3%) antibody levels. Most patients reported that intracapillary testing was easy, convenient, and that they preferred it to conventional venepuncture.Interpretation: Low-volume intracapillary blood sampling was equivalent to conventional venepuncture for the measurement of biologic drug and anti-drug antibodies. Patients preferred intra-capillary testing to conventional venepuncture. Irrespective of future COVID-19 surges, patient-led intracapillary blood sampling is likely to become a key adjunct to telemedicine in patients with immune-mediated inflammatory diseases.Funding: Novo Nordisk Foundation. NIHR Exeter Clinical Research Facility. The Academic Department of Blood Sciences, RDE NHS Trust.Declaration of Interests: All authors have completed the ICMJE Form for Disclosure of Potential Conflicts of Interest and declare: D.C received honoraria from Ferring and Pfizer outside of this work; N.A.K has consulted for Falk and received honoraria from Falk, Allergan, Pharmacosmos and Takeda for unrelated topics and is a deputy editor of Alimentary Pharmacology & Therapeutics Journal; T.A has received unrestricted research grants, advisory board fees, speaker honorariums and support to attend international meetings from AbbVie, Merck, Janssen, Takeda, Ferring, Tillotts, Ferring, Pfizer, NAPP, Celltrion, Hospira for unrelated topics, no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work. R.N, B.H, E.J, S.H, C.R, V.C, K.P, J.R.G and T.J.M have no conflicts of interest to declare.Ethics Approval Statement: The sponsor was the Royal Devon and Exeter NHS Foundation Trust and the South West Research Ethics Committee approved the study (IRAS Reference Number: 286396; July 2020).

Short‐term results of clinical monitoring of biosimilar infliximab in non‐infectious uveitis

AbstractPurposeTo observe the efficacy, safety and immunogenicity of biosimilar infliximab (CT‐P13) in patients with refractory non‐infectious uveitis (NIU).MethodsRetrospective observational study. Indication for treatment was active uveitis unresponsive to classical immunosuppressants. Clinical data were retrospectively analyzed at baseline and 3 months of treatment. The main outcome measures were uveitis activity, adverse effects and serum biosimilar infliximab trough concentrations as well as anti‐infliximab antibodies (ATI).ResultsNine patients received biosimilar IFX after failing classical immunosuppressive treatment. Mean age was 53 years. The most common diagnosis was Birdshot (n = 4), followed by sarcoidosis (n =3 ), Behcet (n = 1), and Sympathetic Ophthalmia (n = 1). The duration of treatment ranged from 18 to 192 weeks. Five patients without active disease and one patient with activity had IFX levels >9 μg/mL. Two patients with active disease and 1 patient in remission had undetectable levels of IFX. Two patients with undetectable levels of IFX had positive anti‐infliximab antibodies (ATI) levels; both patients showed activity. The other patient with undetectable levels of IFX had no ATI and was in remission. None of the patients with IFX levels >9 μg/mL had positive ATI levels. One patient dropped out of treatment due to infusion‐related skin eruptions.ConclusionBiosimilars are pharmacologically highly similar to an approved biological pharmaceutical ‘reference’ product, but are not exact copies. Even if limited to a small group, this study provides evidence that low biosimilar IFX trough levels associate with increased antibodies in most, but not in all cases.The clinical use of measuring biosimilar infliximab (IFX) trough levels and antibodies against IFX (ATIs) remains unclear.

P027 Could Fecal Calprotectin Guide the Therapeutic Regimen of Infliximab in Inflammatory Bowel Disease?

BACKGROUND: Infliximab is a monoclonal antibody against tumor necrosis factor α approved for induction and maintenance of remission in inflammatory bowel disease (IBD). Therapeutic monitoring, with determination of infliximab levels, allows to guide therapeutic decisions and helps to prevent loss of response. AIM: To identify predictive factors of non-therapeutic infliximab levels (<0.50 µg/mL) in IBD patients. METHODS: Retrospective single-center study including patients treated with infliximab with at least one determination of infliximab levels and with a minimum follow-up of six months. Clinical and demographic data obtained included disease phenotype, surgical background, duration of infliximab therapy, presence of anti-infliximab antibodies at the time of analysis, concomitant immunomodulator therapy, compliance, occurrence of an infusion reaction and biochemical assessment at the time of first induction infusion. RESULTS: 104 patients were included, 56 females (53.8%) with a mean age of 38.2 ± 13.1 years. The overall prevalence of non-therapeutic infliximab levels was 29.8%. In the majority (90.4%) of the patients, the first determination was performed during maintenance therapy. 29.0% of the patients with non-therapeutic levels had simultaneously positive antibodies, and of the remainder, 27.3% acquired antibodies in a subsequent analysis. It was found that patients with non-therapeutic levels had significantly higher fecal calprotectin values at the initiation of treatment with infliximab (1184 ± 679 vs 708 ± 621, P = 0.02). No statistically significant association was found with other analytical parameters, like haemoglobin (12.7 ± 1.7 vs 12.9 ± 1.6, P = 0.55), C-reactive protein (11.2 ± 12.2 vs 15.9 ± 20.0, P = 0.22), sedimentation rate (22.4 ± 20.7 vs 23.7 ± 19.3, P = 0.76), ferritin (138.3 ± 128.2 vs 165.5 ± 166.6, P = 0.42) or albumin (3.50 ± 0.45 vs 3.56 ± 0.47, P = 0.54). CONCLUSION(S): Patients with non-therapeutic levels of infliximab have higher values of calprotectin prior to treatment, which may be related to increased inflammatory activity. In these cases infliximab regimens with higher and/or more frequent doses may be considered.

Monitoring of infliximab trough levels and anti-infliximab antibodies in inflammatory bowel diseases: A comparison of three commercially available ELISA kits

BackgroundThere are many studies presenting data of biologics and several ELISA kits commercially available for monitoring infliximab serum trough levels (s-IFXt) and anti-drug antibodies (ADAb). We propose to compare technical characteristics and results of three different assays on a cohort of 35 patients under infliximab (IFX) and suffering from inflammatory bowel disease (IBD). Patients and methodss-IFXt and ADAb were systematically measured with three ELISA kits: Lisa-Tracker® Duo infliximab (Theradiag®), Ridascreen® IFX Monitoring (R-Biopharm AG®) and Promonitor® IFX (Progenika Biopharma SA®). ResultsThe main technical features that differed between kits for measuring s-IFXt were: (i) TNF coating, (ii) immune complexes revelation strategy and/or (iii) interference with other anti-TNFα agents. For kits measuring ADAb, they were revelation steps and unit of results. There was an excellent mathematical correlation of s-IFXt between assays however Bland-Altman analysis denoted (i) s-IFXt were on average 48 to 69% higher in Ridascreen® than in the other two assays, and (ii) elevated s-IFXt were higher with Promonitor® compared to Lisa-Tracker®. As a consequence, there were some substantial discrepancies between assays for classification of s-IFXt into concentration ranges. Despite unstandardized units, pairwise qualitative comparison showed a perfect agreement between the three pairs of ADAb assays. ConclusionOur data show that the evaluated assays are not quantitatively interchangeable due to substantial variations in some results that could lead, for some patients, to divergent therapeutic decisions. We remind to be cautious when comparing study results issued from different kits and recommend using the same assay for the longitudinal follow-up of IBD patients.

Neutralizing effects of anti-infliximab antibodies on synergistically-stimulated human coronary artery endothelial cells

Background and aimsPatients with rheumatic diseases have an increased risk of atherosclerosis with up-regulated serum amyloid A (SAA), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), which were reported to activate human coronary artery endothelial cells (HCAEC). We aimed to investigate the effects of TNF-α inhibitor infliximab and anti-infliximab antibodies on the TNF-α/IL-1β/SAA activated HCAEC. MethodsHCAEC were incubated with TNF-α, IL-1β, SAA, infliximab, anti-infliximab antibodies and their combinations. The protein levels of pro- and anti-atherogenic analytes were measured in supernatants using ELISA and multiplex assays, while mRNA expression was determined by RT-PCR. Anti-infliximab antibodies were purified from sera samples by affinity chromatography. ResultsIL-6, IL-8, GM-CSF and GRO-α were synergistically up-regulated in triple stimulation with TNF-α, IL-1β and SAA, while their levels in solely SAA- or TNF-α-stimulated HCAEC did not increase. IL-1Ra, IL-1α, VCAM-1, MCP-1, IL-10 and IL-17A were increased, but no synergistic responses were observed in triple stimulation. Infliximab was effective in lowering the synergistic effect of IL-6, IL-8, GM-CSF and GRO-α in triple stimulation, while anti-infliximab antibodies restored the levels. The changes were confirmed at the mRNA expression level for IL-6, IL-8 and GM-CSF. ConclusionsTriple stimulation with TNF-α, IL-1β and SAA synergistically elevated IL-6, IL-8, GM-CSF and GRO-α release in supernatants of HCAEC, with infliximab substantially inhibiting their levels. An isolated, enriched fraction of polyclonal anti-infliximab antibodies was capable of neutralizing infliximab, in the presence of TNF-α/IL-1β/SAA. The long-term presence of anti-infliximab antibodies in the circulation of patients with chronic rheumatic diseases is potentially important for promoting the atherosclerotic process.

Anti-infliximab antibodies: How to compare old and new data?

BackgroundAnti-drug-antibodies (ADA) against infliximab are frequently measured in patients receiving infliximab treatment with loss of response and undetectable infliximab concentrations. Different ADA bridging assays (1st generation, 2nd generation and ready-to-use kit) have been developed successively and were applied over the last 10 years, making comparison between ADA concentrations very challenging. A cutoff of 8 μg/ml was established to discriminate low from high ADA concentrations using the 1st generation ADA bridging assay. The objective of this study was to enable comparison of ADA concentrations determined with the different assays that were developed over the years. Methods166 serum samples were collected from patients with inflammatory bowel disease treated with infliximab. 98 samples were measured simultaneously with the 1st and 2nd generation ADA assay, 67 serum samples were measured with the 2nd generation assay and the ready-to-use kit. ResultsFrom our ADA concentration comparison experiments, we deduced that the previously established cutoff of 8 μg/ml with the 1st generation ELISA has a similar impact as the cutoff of 374 ng/ml with the 2nd generation ELISA and a cutoff of 119 ng/ml in the ready-to-use ELISA kit. ConclusionADA concentrations measured with the different assays were compared and a cutoff concentration was determined for each of them to distinguish between low and high ADA concentrations. These cutoff concentrations may serve as a tool for clinicians to make treatment decisions for patients with a loss of response to infliximab and undetectable infliximab serum concentrations.

P058 Serum infliximab and corresponding anti-infliximab antibody: Analysis of over 30,000 patient results using lab developed chemiluminescent immunoassays

BACKGROUND: Assays to measure TNF inhibitors and anti-drug antibodies (ADAb) in patient serum are being utilized to manage failure to respond and loss of response. These monitoring assays may also be used to proactively titrate doses and dosing intervals (1). Here, 37,165 infliximab (IFX) patient results over 4 years were analyzed. METHODS: Measurements of drug and ADAb levels were performed by lab developed chemiluminescent immunoassays (2). The lower limits of quantitation are 0.4 μg/mL for IFX and 22 ng/mL for its ADAb. Drug assays measure free (ADAb-unbound) drug while ADAb assays detect total antibodies (including IgM and IgG subtypes) and are drug- tolerant to the presence of up to &gt;50 μg/mL of drug. Clinical histories and blood collection timing are unknown. RESULTS: Of 37,165 measured IFX samples, 55% (20,359) were ADAb-free and 45% (16,806) had measurable anti-infliximab antibodies, ranging in concentration from 22 to 3.5 million ng/mL. In the absence of ADAb, IFX concentrations were from 0.4 to &gt;50 μg/mL, with the majority (&gt;60%) between 3.0 to 20 μg/mL. In the presence of ADAb, an inverse relationship between IFX concentrations and anti-IFX antibodies was demonstrated. As a baseline reference, an ADAb-free mean drug level from 16,463 samples with IFX between 0.4 and 30 μg/mL was found to be 10.0 μg/mL. Mean IFX concentrations decreased in samples with increasing ADAb. Low ADAb (&lt;200 ng/mL) appears to have minimal impact on mean drug levels while high ADAb (&gt;1,000 ng/mL) is invariably associated with severely diminished IFX (10% or less than the mean). CONCLUSION(S): Upon analysis of 37,165 infliximab patient samples, 45% exhibited anti-infliximab antibodies. Though collection timing and clinical histories are not known, we found that of all ADAb- free samples, about one third (36%) were within the target range of 3–10 μg/mL for infliximab and 36% of samples were subtherapeutic at &lt;3.0 μg/mL. High titer ADAb are almost invariably associated with very low or absent IFX levels. In contrast, low titer antibodies have little or no impact on drug levels. Our findings are consistent with American Gastroenterological Association Critical Care Pathways for Crohn's Disease and Ulcerative Colitis where low and high antibody scenarios are managed very differently (increase drug dose/consider immunomodulatory vs switch within class). It may be possible to treat away low titer ADAb by increasing drug or adding an immunomodulator (3). Therefore, drug-tolerant anti-drug antibody assays that have been designed both (1) to detect low level ADAb and (2) to distinguish low to intermediate to high titers with high resolution (from 22 to 2,000+ ng/mL) may be most helpful in preventing, managing and treating immunogenicity.

Infliximab and biosimilar infliximab in psoriasis: efficacy, loss of efficacy, and adverse events.

Psoriasis is a chronic immune-mediated skin disease affecting multiple systems, and tumor necrosis factor-α (TNF-α) plays a significant role in the initiation and progression of the disease process. Psoriasis has a high prevalence rate in the Western world, especially in the USA and Australia; in China, although the prevalence rate is much lower, there is still a large number of patients suffering from psoriasis and its comorbidities. As TNF-α is thought to be crucial in the pathogenesis of psoriasis, specific therapy blocking TNF-α may be beneficial in the treatment of this disease. Infliximab, a murine–human monoclonal antibody, is highly efficacious in the treatment of moderate-to-severe psoriasis, with better skin clearance and faster onset of action than topical medications such as methotrexate, narrow-band ultraviolet B, and calcipotriol. Lack of adherence to infliximab therapy is mainly due to loss of response (LOR) over time and adverse events, particularly because infusion reactions are usually encountered. Anti-infliximab antibody is thought to be responsible for the LOR and infusion reactions. However, the mechanism underlying the formation of anti-infliximab antibody and its side effects remains unclear. Further studies identifying patients at risk for LOR will probably help clinicians to select the right patients for anti-TNF-α therapy and to increase the durability of the treatment. This review discusses the efficacy of infliximab as demonstrated by various clinical trials, LOR to infliximab, combatting LOR, as well as the adverse events usually faced during the use of infliximab therapy and the infliximab biosimilar Remsima®. We hope that we can discover a better way to use infliximab in the therapy of psoriasis from the current research data.

A Surface Plasmon Resonance-based assay to measure serum concentrations of therapeutic antibodies and anti-drug antibodies

Therapeutic drug and immunogenicity monitoring (TDIM) is increasingly proposed to guide therapy with biologics, characterised by high inter-individual variability of their blood levels, to permit objective decisions for the management of non-responders and reduce unnecessary interventions with these expensive treatments. However, TDIM has not yet entered clinical practice partly because of uncertainties regarding the accuracy and precision of enzyme-linked immunosorbent assays (ELISA). Here we report the characterisation of a novel surface plasmon resonance (SPR)-based TDIM, applied to the measurement of serum concentrations of infliximab, an antibody against tumour necrosis factor α (anti-TNFα), and anti-infliximab antibodies. SPR has the obvious advantages of directly detecting and measuring serum antibodies in minutes, avoiding the long incubation/separation/washing/detection steps of the methods proposed so far, reducing complexity and variability. Moreover, drug and anti-drug antibodies can be measured simultaneously. This new method was validated for sensitivity and reproducibility, and showed cost-effectiveness over commercial ELISA kits. This method may be applied to other biotherapeutics. These data pave the way for the development of SPR-based point-of-care devices for rapid on-site analysis.

Comparison of three commercially-available elisa assays for anti-infliximab antibodies

Comparison of three commercially-available elisa assays for anti-infliximab antibodies

P554 Point of Care detection of anti-infliximab antibodies in inflammatory bowel disease patients treated with the biosimilar SB2: performance comparison with ELISA

P554 Point of Care detection of anti-infliximab antibodies in inflammatory bowel disease patients treated with the biosimilar SB2: performance comparison with ELISA

P202 Quantum blue anti-infliximab: development and evaluation of a point of care rapid test for measuring anti-infliximab antibodies in human serum

P202 Quantum blue anti-infliximab: development and evaluation of a point of care rapid test for measuring anti-infliximab antibodies in human serum

Serum Levels of Infliximab and Anti-Infliximab Antibodies in Brazilian Patients with Crohn's Disease

OBJECTIVES:The aim of this study was to evaluate the quantitative serum level of infliximab (IFX) as well as the detection of anti-infliximab antibodies (ATIs) in patients with Crohn's disease (CD).METHOD:Forty patients with CD under treatment at a tertiary center in southeastern Brazil were evaluated. Their use of infliximab was continuous and regular. We analyzed and compared the differences in the IFX and ATI levels between the patients with active CD (CDA) and those with CD in remission (CDR).RESULTS:There was no difference in the IFX level between the CDA and CDR groups (p>0.05). Eighty percent of all patients had IFX levels above the therapeutic concentration (6-10 μg/mL). Two (9%) of the 22 patients with active disease and four (22.2%) of the 18 patients in remission had undetectable levels of IFX. Four (66.6%) of the six patients with undetectable levels of IFX had positive ATI levels; three of these patients were in remission, and one had active disease. In addition, the other two patients with undetectable levels of IFX presented ATI levels close to positivity (2.7 and 2.8 AU/ml). None of the patients with therapeutic or supratherapeutic IFX levels had positive ATI levels.CONCLUSIONS:The undetectable levels of IFX correlated with the detection of ATIs, which was independent of disease activity. Immunogenicity was not the main factor for the loss of response to IFX in our study, and the majority of patients in both groups (CDA and CDR) had supratherapeutic levels of IFX.

Causes of Treatment Failure in Children With Inflammatory Bowel Disease Treated With Infliximab: A Pharmacokinetic Study.

Anti-tumor necrosis factor antibodies have led to a revolution in the treatment of inflammatory bowel diseases (IBD); however, a sizable proportion of patients does not respond to therapy. There is increasing evidence suggesting that treatment failure may be classified as mechanistic (pharmacodynamic), pharmacokinetic, or immune-mediated. Data regarding the contribution of these factors in children with IBD treated with infliximab (IFX) are still incomplete. The aim was to assess the causes of treatment failure in a prospective cohort of pediatric patients treated with IFX. This observational study considered 49 pediatric (median age 14.4) IBD patients (34 Crohn disease, 15 ulcerative colitis) treated with IFX. Serum samples were collected at 6, 14, 22 and 54 weeks, before IFX infusions. IFX and anti-infliximab antibodies (AIA) were measured using enzyme linked immunosorbent assays. Disease activity was determined by Pediatric Crohn's Disease Activity Index or Pediatric Ulcerative Colitis Activity Index. Clinical remission, defined as a clinical score <10, was obtained by 76.3% of patients at week 14 and by 73.9% at week 54. Median trough IFX concentration was higher at all time points in patients achieving sustained clinical remission. IFX levels during maintenance correlated also with C-reactive protein, albumin, and fecal calprotectin. After multivariate analysis, IFX concentration at week 14 >3.11 μg/mL emerged as the strongest predictor of sustained clinical remission. AIA concentrations were correlated inversely with IFX concentrations and directly with adverse reactions. Most cases of therapeutic failure were associated with low serum drug levels. IFX trough levels at the end of induction are associated with sustained long-term response.

Serum levels of infliximab in Brazilian patients with Crohn's disease: what are the reasons for differences from previous studies?

Dear Sir, It was with significant interest that we read the manuscript, entitled “Serum Levels of Infliximab and Anti-Infliximab Antibodies in Brazilian Patients with Crohn’s Disease”, recently published in this distinguished journal by Gomes et al. (). In this study, the authors measured the serum infliximab (IFX) levels of 40 patients with Crohn’s disease (CD) and correlated their findings with disease activity. There was no difference in the IFX level between patients with active disease and those with remission (p

Clinical relevance of detecting anti-infliximab antibodies with a drug-tolerant assay: post hoc analysis of the TAXIT trial

目的 评估在药物谷浓度（trough concentration，TC）调整后的英夫利昔单抗治疗随机对照试验（TAXIT）事后分析中，使用药物耐受性检测法测定药物抗体水平的临床相关性。 研究设计 本研究共纳入76名已入组TAXIT试验的，初筛时英夫利昔单抗药物谷浓度<3 μg/ml的患者血清样本（n=221）在进行优化处理后对血清样本进行了再分析，研究末亦进行了药物耐受性法检测。随机化分组前这些患者们接受了更高剂量的药物治疗，提升英夫利昔单抗药物谷浓度至治疗浓度范围即（3~7）μg/ml。根据测定的抗药抗体滴度将患者分组（四分位分组法，Q1~4）。 结果 应用药物耐受性检测法，初筛时免疫原性检测阳性率从21%（药物敏感性检测法）提升至63%，优化处理后自0%升至51%，而TAXIT试验末这一组数字为3%与42%。抗药抗体第4四分位组患者为达药物谷浓度目标范围需更大的英夫利昔单抗累积用药剂量[2 390 mg（880~2 998）]，从而导致更高的药物相关花费[10 712欧元（4 120~13 596）]。而抗药抗体阴性患者及抗药抗体第1/第2四分位组患者药物相关花费低至平均2 060欧元（1 648~3 296）与2 060欧元（1 648~4 120）/2 060欧元（1 751~3 296），P<0.001。然而，除1名抗药抗体第4四分位组的患者外，所有的患者药物敏感性检测中抗药抗体均阳性。 结论 强化药物剂量后，随着时间推移，药物敏感性测定法无法检出的低浓度抗药抗体在超过半数的患者中消失，且与临床无相关性。相反，在药物敏感性测定中亦可检测出的高浓度抗药抗体，不会随着时间推移消失，且以上患者需更高的药物累积剂量及更多的药物相关性花费。在这样的患者中，主动更换药物可能更具成本效益。 临床试验登记 2011-002061-38；事后结果。