Development of a new immunoassay for the accurate determination of anti-infliximab antibodies in inflammatory bowel disease

Comparison of the Pharmacokinetics of CT-P13 Between Crohn's Disease and Ulcerative Colitis

BACKGROUND

We aimed to compare trough infliximab levels and the development of antidrug antibody (ADA) for 1 year between Crohn's disease (CD) and ulcerative colitis (UC) patients who were biologic-naive, and to evaluate their impact on clinical outcomes.

METHODS

This was a prospective, multicenter, observational study. Biologic-naive patients with moderate to severe CD or UC who started CT-P13, an infliximab biosimilar, therapy were enrolled. Trough drug and ADA levels were measured periodically for 1 year after CT-P13 initiation.

RESULTS

A total of 267 patients who received CT-P13 treatment were included (CD 168, UC 99). The rates of clinical remission (72% vs. 32.3%, P <0.001) at week 54 were significantly higher in CD than in UC. The median trough drug level (μg/mL) was significantly higher in CD than in UC up to week 14 (week 2, 18.7 vs. 14.7, P <0.001; week 6, 12.5 vs. 8.6, P <0.001; week 14, 3.4 vs. 2.5, P =0.001). The median ADA level (AU/mL) was significantly lower in CD than in UC at week 2 (6.3 vs. 6.5, P =0.046), week 30 (7.9 vs. 11.8, P =0.007), and week 54 (9.3 vs. 12.3, P =0.032). Development of ADA at week 2 [adjusted odds ratio (aOR)=0.15, P =0.026], initial C-reactive protein level (aOR=0.87, P =0.032), and CD over UC (aOR=1.92, P <0.001) were independent predictors of clinical remission at week 54.

CONCLUSION

Infliximab shows more favorable pharmacokinetics, including high drug trough and low ADA levels, in CD than in UC, which might result in better clinical outcomes for 1-year infliximab treatment in CD patients.

A Systematic Review on the interest of Drug Tolerant assay in the monitoring of Inflammatory Bowel Disease

Many patients with inflammatory bowel disease (IBD) are treated with anti-tumor necrosis factor (TNF) therapies, of which infliximab (IFX) is most commonly used. Loss of response (LOR) to anti-TNF therapy due to immunogenic failure accounts for 20% of subsequent medical intervention and is defined, using a drug sensitive assay, as low or undetectable concentration of drug with high titers of anti-drug antibodies (ADAb). We performed a systematic review to investigate the use of a drug tolerant assay during both induction and maintenance to monitor patients treated with anti-TNFs. After the search on PubMed, 90 publications were reviewed. Most ADAb detection methods are drug sensitive, cannot detect ADAb in the presence of drug, and therefore cannot be used close to drug administration, when the drug concentration is too high. To overcome this major limitation, several drug-tolerant techniques have been developed and will be discussed in this review. Using drug-tolerant assays ADAb against infliximab (IFX) or adalimumab (ADM) can be detected during induction and predict primary non-response or LOR. Drug sensitive assays do not allow detection of ADAb during the induction phase as IFX or ADM concentration is typically high.

Atomic Force Microscopy Application for the Measurement of Infliximab Concentration in Healthy Donors and Pediatric Patients with Inflammatory Bowel Disease

The use of infliximab has completely changed the therapeutic landscape in inflammatory bowel disease. However, despite its proven efficacy to induce and maintain clinical remission, increasing evidence suggests that treatment failure may be associated with inadequate drug blood concentrations. The introduction of biosensors based on different nanostructured materials for the rapid quantification of drugs has been proposed for therapeutic drug monitoring. This study aimed to apply atomic force microscopy (AFM)-based nanoassay for the measurement of infliximab concentration in serum samples of healthy donors and pediatric IBD patients. This assay measured the height signal variation of a nanostructured gold surface covered with a self-assembled monolayer of alkanethiols. Inside this monolayer, we embedded the DNA conjugated with a tumor necrosis factor able to recognize the drug. The system was initially fine-tuned by testing known infliximab concentrations (0, 20, 30, 40, and 50 nM) in buffer and then spiking the same concentrations of infliximab into the sera of healthy donors, followed by testing pediatric IBD patients. A good correlation between height variation and drug concentration was found in the buffer in both healthy donors and pediatric IBD patients (p-value < 0.05), demonstrating the promising use of AFM nanoassay in TDM.

Low immunogenicity of vedolizumab determined by a simple drug-tolerant assay in patients with ulcerative colitis

Vedolizumab is a humanized monoclonal antibody against the α4β7 integrin and is approved for treatment of inflammatory bowel diseases. In this study, we evaluated the immunogenicity of vedolizumab using a simple drug-tolerant assay developed in our laboratory. Serum vedolizumab trough levels and anti-vedolizumab antibody (AVA) levels were measured using new immunoassays in 37 patients with ulcerative colitis (UC) under vedolizumab maintenance therapy. The median vedolizumab trough level at week 30 was 16.0 μg/ml (interquartile range, 7.3–24.4). The vedolizumab trough level of the patients with clinical remission (partial Mayo score ≤1) was significantly higher than that of clinically active patients (16.7 μg/ml vs 6.8). The cut-off value of vedolizumab level predicting clinical remission at week 30 was 7.34 μg/ml. The median AVA level of patients under vedolizumab maintenance therapy was similar to that of healthy controls (n = 20) (0.032 μg/ml-c vs 0.022). One of 37 patients (2.7%) was judged to be AVA positive. There was no significant difference in serum AVA and vedolizumab trough levels between biologics-naïve (n = 19) and biologics-switched (prior anti-TNFα-exposed) patients (n = 18). In conclusion, the simple drug-tolerant assay developed in our laboratory demonstrated low immuno­genicity of vedolizumab. Prior use of anti-TNFα drugs did not affect the immunogenicity of vedolizumab.

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.

Clinical relevance of innovative immunoassays for serum ustekinumab and anti-ustekinumab antibody levels in Crohn's disease

BACKGROUND AND AIM

Ustekinumab is a human monoclonal antibody to the p40 subunit of human IL-12/IL-23. The purpose of this report is to verify the newly developed immunoassays for serum ustekinumab and anti-ustekinumab antibody (AUA) concentrations and assess their clinical utility.

METHODS

Serum ustekinumab trough levels and AUA levels were measured using new immunoassays in 38 patients with Crohn's disease under ustekinumab maintenance injection.

RESULTS

Mean ustekinumab trough levels were 2.54 ± 2.1 μg/mL, and 3 of 38 patients (7.9%) were positive for AUAs. There was no association between ustekinumab trough levels and AUA levels. The optimal trough level of ustekinumab to maintain negative C-reactive protein levels (≤ 0.3 mg/dL) was 1.67 μg/mL determined by receiver operating characteristic curve analysis. Ustekinumab trough level negatively but significantly correlated with C-reactive protein, erythrocyte sedimentation rate, and Crohn's disease activity index and positively and significantly correlated with serum albumin levels. Ustekinumab trough levels were significantly higher in biologics-naïve patients than in biologics-experienced patients, although there was no difference in AUA levels.

CONCLUSIONS

We developed new assays for serum ustekinumab trough and AUA levels. These assays might provide new insights into therapeutic drug monitoring-based management of Crohn's disease patients under ustekinumab therapy.

Loss of response to scheduled infliximab therapy for Crohn's disease in adults: A systematic review and meta-analysis

OBJECTIVE

To determine the potential predictors of loss of response (LOR) to infliximab (IFX) maintenance therapy for adult patients with Crohn's disease (CD).

METHODS

We searched for English-language articles published between 1990 and March 2017 in PubMed, Embase, and the Cochrane Library. After identifying eligible studies, data extraction was performed independently by two reviewers. The potential prognostic variables were identified and dichotomized for meta-analysis. Based on the heterogeneity among study variables, random-effects models was used in our meta-analysis.

RESULTS

Twenty-six studies met our eligibility criteria and consolidated drug response data were obtained from 3212 patients. The pooled rate of LOR to IFX maintenance therapy with a median follow-up of 1.1 years was 34%. The incidence of LOR to IFX therapy was increased in CD patients with perianal lesions (odds ratio [OR] 1.69, 95% confidence interval [CI] 1.04-2.75, P = 0.03), colon involvement (OR 2.56, 95% CI 1.20-5.50, P = 0.02) and younger age at CD onset (standardized mean difference -0.79, 95% CI -1.41 to -0.18, P = 0.01).

CONCLUSIONS

The meta-analysis estimates the incidence of LOR among adult CD patients undergoing IFX therapy is 34%. The presence of perianal lesions, younger age at CD onset, and involvement of the colon are relative risk factors of LOR in CD patients received scheduled IFX maintenance therapy.

Current new challenges in the management of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory condition of the gastrointestinal tract. Although the cause of UC is postulated to be multifactorial in nature, including genetic predisposition, epithelial barrier defects, dysregulation of immune responses, and environmental factors, the specific pathogenesis of UC is still incompletely understood. In the treatment of UC so far, a method of suppressing immunity and treating it has been mainstream. Immunosuppressant drugs, including thiopurines (azathioprine or 6-mercaptopurine), anti-tumor necrosis factor-α (anti-TNF-α) antibody (infliximab and adalimumab), and calcineurin inhibitor, can be used in treat patients with corticosteroid-dependent and/or corticosteroid-refractory moderate-to-severe UC. Recently, in addition to such a conventional therapeutic agent, golimumab, which is the first transgenic human monoclonal anti-TNF-α antibody to be fabricated, anti α-4/β-7 integrin antibody, and Janus kinase inhibitor have been reported to novel immunosuppressant therapy. Furthermore, other treatments with unique mechanisms different from immunosuppression, have also been suggested, including fecal microbiota transplantation and Indigo naturalis, which is a Chinese herbal medicine. We compared the features and efficacy of these new treatments. In this issue, the features and treatment options for these new treatments is reviewed.

Verification between Original and Biosimilar Therapeutic Antibody Infliximab Using nSMOL Coupled LC-MS Bioanalysis in Human Serum

Background:

Infliximab (IFX) is a chimeric therapeutic monoclonal antibody targeting tumor necrosis factor alpha (TNFα)-mediated inflammatory immune diseases. However, despite of an initial good clinical response, decrease in response to long-term treatment is a common observation.

Objective:

Recent studies suggest that IFX level in circulation has a correlation with clinical bioavailabil-ity. Therefore, the management of IFX dosage for individual manifestation by IFX monitoring may be valuable for the improvement of therapeutic response and outcomes.

Method:

In order to develop a broad IFX therapeutic monitoring in human serum, we have developed the validated IFX bioanalysis for RemicadeTM and its biosimilar product using our nano-surface and molecu-lar-orientation limited proteolysis (nSMOL) technology coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The nSMOL chemistry has a unique property of Fab-selective prote-olysis, and makes it possible a global bioanalysis for many monoclonal antibodies.

Results:

The quantitation range of IFX in serum was from 0.293 to 300 μg/ml with good linearity. Quan-titation verification at the concentrations of 0.293, 0.879, 14.1 and 240 μg/ml was within 1.56-7.53% of precision and 98.9-111% of accuracy using H-chain signature peptide SINSATHYAESVK. Moreover, cross-verified bioanalysis of Remicade quantitation using biosimilar standard, and its opposite combina-tion, obtained an identical and inter-comparative results.

Conclusion:

The nSMOL strategy has the potential as a practical therapeutic monitoring technology in IFX therapeutic applications.

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

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

Trough level of infliximab is useful for assessing mucosal healing in Crohn's disease: a prospective cohort study

Background/Aims

Decreased trough levels of infliximab (TLI) and antibodies to infliximab (ATI) are associated with loss of response (LOR) in Crohn's disease. Two prospective studies were conducted to determine whether TLI or ATI better correlates with LOR (Study 1), and whether TLI could become a predictor of mucosal healing (MH) (Study 2).

Methods

Study 1 was conducted in 108 patients, including those with LOR and remission to compare ATI and TLI in discriminating the 2 conditions based on receiver operating characteristic (ROC) curve analyses. Study 2 involved 35 patients who were evaluated endoscopically.

Results

In Study 1, there were no differences between the 2 assays in ROC curve analyses; the TLI cutoff value for LOR was 2.6 µg/mL (sensitivity, 70.9%; specificity, 79.2%), and the ATI cutoff value was 4.9 µg/mL (sensitivity, 65.5%; specificity, 67.9%). The AUROC (area under the ROC curve) of TLI was greater than that of ATI. AUROC was useful for discriminating between the 2 conditions. In Study 2, the TLI was significantly higher in the colonic MH group than in the non-MH group (2.7 µg/mL vs. 0.5 µg/mL, P=0.032).

Conclusions

TLI is better than ATI for clinically diagnosing LOR, and a correlation was observed between TLI and colonic MH.

Clinical effectiveness and cost-effectiveness of use of therapeutic monitoring of tumour necrosis factor alpha (TNF-α) inhibitors [LISA-TRACKER® enzyme-linked immunosorbent assay (ELISA) kits, TNF-α-Blocker ELISA kits and Promonitor® ELISA kits] versus standard care in patients with Crohn's disease: systematic reviews and economic modelling

BACKGROUND AND OBJECTIVES

Systematic reviews and economic modelling of clinical effectiveness and cost-effectiveness of therapeutic monitoring of tumour necrosis factor alpha (TNF-α) inhibitors [using LISA-TRACKER^® enzyme-linked immunosorbent assay (ELISA) kits (Theradiag, Marne La Vallee, France, or Alpha Laboratories, Heriot, UK), TNF-α-Blocker ELISA kits (Immundiagnostik AG, Bensheim, Germany) and Promonitor^® ELISA kits (Proteomika, Progenika Biopharma, Bizkaia, Spain)] versus standard care for Crohn's disease (CD).

METHODS

Multiple electronic databases were searched from inception to December 2014 in order to identify primary studies and meta-analyses.

POPULATION

Patients with moderate to severe active CD treated with infliximab (IFX) (Remicade^®, Merck Sharp & Dohme Ltd, Kenilworth, NJ, USA) or adalimumab (ADA) (Humira^®, AbbVie Inc., North Chicago, IL, USA).

INTERVENTION

Monitoring of serum anti-TNF-α (IFX or ADA) and/or of anti-drug antibody levels using test assays with a test-treatment algorithm.

COMPARATOR

Standard care.

OUTCOMES

Any patient-related outcome, test agreement and cost-effectiveness estimates. The quality assessments used recognised checklists (Quality Assessment of Diagnostic Accuracy Studies-2, Cochrane, Philips and Consolidated Health Economic Evaluation Reporting Standards). Evidence was synthesised using narrative review and meta-analysis. A Markov model was built in TreeAge Pro 2013 (TreeAge Software, Inc., Williamstown, MA, USA). The model had a 4-week cycle and a 10-year time horizon, adopted a NHS and Personal Social Services perspective and used a linked evidence approach. Costs were adjusted to 2013/14 prices and discounted at 3.5%.

RESULTS

We included 68 out of 2434 and 4 out of 2466 studies for the clinical effectiveness and cost-effectiveness reviews, respectively. Twenty-three studies comparing test methods were identified. Evidence on test concordance was sparse and contradictory, offering scant data for a linked evidence approach. Three studies [two randomised controlled trials (RCTs) and one retrospective observational study] investigated outcomes following implementation of a test algorithm. None used the specified commercial ELISA immunoassay test kits. Neither of the two RCTs demonstrated clinical benefit of a test-treatment regimen. A meta-analysis of 31 studies to estimate test accuracy for predicting clinical status indicated that 20-30% of test results are likely to be inaccurate. The four cost-effectiveness studies suggested that testing results in small cost reductions. In the economic analysis the base-case analysis showed that standard practice (no testing/therapeutic monitoring with the intervention tests) was more costly and more effective than testing for IFX. Sensitivity and scenario analyses gave similar results. The probabilistic sensitivity analysis indicated a 92% likelihood that the 'no-testing' strategy was cost-effective at a willingness to pay of £20,000 per quality-adjusted life-year.

STRENGTHS AND LIMITATIONS

Rigorous systematic reviews were undertaken; however, the underlying evidence base was poor or lacking. There was uncertainty about a linked evidence approach and a lack of gold standard for assay comparison. The only comparative evidence available for economic evaluation was for assays other than the intervention assays.

CONCLUSIONS

Our finding that testing is not cost-effective for IFX should be viewed cautiously in view of the limited evidence. Clinicians should be mindful of variation in performance of different assays and of the absence of standardised approaches to patient assessment and treatment algorithms.

FUTURE WORK RECOMMENDATIONS

There is substantial variation in the underlying treatment pathways and uncertainty in the relative effectiveness of assay- and test-based treatment algorithms, which requires further investigation. There is very little research evidence on ADA or on drug monitoring in children with CD, and conclusions on cost-effectiveness could not be reached for these.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014015278.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Immunogenicity of biologics in inflammatory bowel disease

Crohn's disease and ulcerative colitis are chronic inflammatory disorders of the gastrointestinal tract. Treatment options include biologic therapies; however, a proportion of patients lose response to biologics, partly due to the formation of anti-drug antibodies (ADAbs). Concomitant immunosuppressive agents reduce the development of ADAbs. This review article aims to assess the immunogenicity of biologic therapies and their clinical implications. A comprehensive literature search was conducted for articles published January 2009 to August 2015 reporting immunogenicity to adalimumab (ADM), certolizumab pegol (CZP), golimumab, infliximab (IFX), ustekinumab, and vedolizumab in inflammatory bowel disease (IBD). Eligible articles were reviewed and quality assessed by independent reviewers. Overall, 122 publications reporting 114 studies were assessed. ADAbs were reported for all agents, but the percentage of patients developing ADAbs was extremely variable, with the highest (65.3%) being for IFX administration to patients with IBD. ADAb presence was frequently associated with a reduction in primary efficacy and a loss of response, and, for IFX, an increase in adverse events (AEs). Lower serum levels of ADM, CZP and IFX were seen in ADAbs-positive rather than ADAbs-negative patients; pharmacokinetic data were unavailable for other therapies. Little information was available regarding the timing of ADAb development; studies reported their detection from as early as 10-14 days up to months after treatment initiation. Biologic therapies carry an intrinsic risk of immunogenicity, although reported rates of ADAbs vary considerably. The clinical implications of immunogenicity are a concern for effective treatment; further research, particularly into the more recently approved biologics, is required.

Effects of Combination Therapy With Immunomodulators on Trough Levels and Antibodies Against Tumor Necrosis Factor Antagonists in Patients With Inflammatory Bowel Disease: A Meta-analysis

BACKGROUND & AIMS

It is not clear whether combination therapy with immunomodulators affects the immunogenicity of tumor necrosis factor (TNF) antagonists in patients with inflammatory bowel disease. We performed a meta-analysis to quantify the effects of combined immunomodulator therapy on the presence of antibodies against TNF antagonists (antidrug antibodies [ADAs]) and trough levels of anti-TNF agents.

METHODS

We systematically searched publication databases for studies that reported prevalence of ADAs in patients who received anti-TNF agents. Raw data from studies that met the inclusion criteria were pooled to determine effect estimates. We performed subgroup and metaregression analyses to determine the level of heterogeneity among study outcomes.

RESULTS

We analyzed findings from 35 studies that met inclusion criteria (results reported from 6790 patients with inflammatory bowel disease). The pooled risk ratio for formation of ADAs in patients receiving combined therapy with immunomodulators, versus that of patients receiving anti-TNF monotherapy, was 0.49 (95% confidence interval, 0.41-0.59; P < .001). However, the pooled analysis did not demonstrate a significant difference in trough levels of anti-TNF agents between patients with versus without concurrent use of immunomodulators (standardized mean difference, 0.11; 95% confidence interval, 0.19-0.41; P = .47). Subgroup analyses of patients treated with different TNF antagonists revealed no difference in the formation of ADAs (P = .50 for interaction); the protective effect of immunomodulators did not differ with type of drug patients were given (methotrexate vs thiopurines), or assay for ADA. We observed heterogeneity only among studies of patients with ulcerative colitis (I² = 76%). Funnel plot and Egger test analyses indicated publication bias in the studies (P = .001).

CONCLUSIONS

In a meta-analysis of published studies, we associated combined treatment with immunomodulators with reduced risk of formation of antibodies against TNF antagonists in patients with inflammatory bowel disease.

Immunogenicity of Biologics in Chronic Inflammatory Diseases: A Systematic Review

OBJECTIVES

A systematic review was conducted to explore the immunogenicity of biologic agents across inflammatory diseases and its potential impact on efficacy/safety.

METHODS

Literature searches were conducted through November 2016 to identify controlled and observational studies of biologics/biosimilars administered for treatment of rheumatoid arthritis (RA), psoriatic arthritis (PsA), juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), non-radiographic axial spondyloarthritis (nr-axSpA), psoriasis (Ps), Crohn's disease, and ulcerative colitis.

RESULTS

Of >21,000 screened publications, 443 were included. Anti-drug antibody (ADAb) rates varied widely among biologics across diseases (and are not directly comparable because of immunoassay heterogeneity); the highest overall rates were reported with infliximab (0-83%), adalimumab (0-54%), and infliximab biosimilar CT-P13 (21-52%), and the lowest with secukinumab (0-1%), ustekinumab (1-11%), etanercept (0-13%), and golimumab (0-19%). Most ADAbs were neutralizing, except those to abatacept and etanercept. ADAb+ versus ADAb- patients had lower rates of clinical response to adalimumab (RA, PsA, JIA, AS, Ps), golimumab (RA), infliximab (RA, PsA, AS, Ps), rituximab (RA), ustekinumab (Ps), and CT-P13 (RA, AS). Higher rates of infusion-related reactions were reported in infliximab- and CT-P13-treated ADAb+ patients. Background immunosuppressives/anti-proliferatives reduced biologic immunogenicity across diseases.

CONCLUSIONS

Based on reviewed reports, biologic/biosimilar immunogenicity differs among agents, with the highest rates observed with infliximab and adalimumab. As ADAb formation in biologic-/biosimilar-treated patients may increase the risk of lost response, the immunogenicity of these agents is an important (albeit not the only) consideration in the treatment decision-making process.

Test accuracy of drug and antibody assays for predicting response to antitumour necrosis factor treatment in Crohn's disease: a systematic review and meta-analysis

OBJECTIVE

To present meta-analytic test accuracy estimates of levels of antitumour necrosis factor (anti-TNF) and antibodies to anti-TNF to predict loss of response or lack of regaining response in patients with anti-TNF managed Crohn's disease.

METHODS

MEDLINE, Embase, the Cochrane Library and Science Citation Index were searched from inception to October/November 2014 to identify studies which reported 2×2 table data of the association between levels of anti-TNF or its antibodies and clinical status. Hierarchical/bivariate meta-analysis was undertaken with the user-written 'metandi' package of Harbord and Whiting using Stata V.11 software, for infliximab, adalimumab,anti-infliximab and anti-adalimumab levels as predictors of loss of response. Prevalence of Crohn's disease in included studies was meta-analysed using a random effects model in MetaAnalyst software to calculate positive and negative predictive values. The search was updated in January 2017.

RESULTS

31 studies were included in the review. Studies were heterogeneous with respect to the type of test used, criteria for establishing response and loss of response, population examined and results. Meta-analytic summary point estimates for sensitivity and specificity were 65.7% and 80.6% for infliximab trough levels and 56% and 79% for antibodies to infliximab, respectively. Pooled results for adalimumab trough levels and antibodies to adalimumab were similar. Pooled positive and negative predictive values ranged between 70% and 80% implying that between 20% and 30% of both positive and negative test results may be incorrect in predicting loss of response.

CONCLUSION

The available evidence suggests that these tests have modest predictive accuracy for clinical status; direct test accuracy comparisons in the same population are needed. More clinical trial evidence from test-treat studies is required before the clinical utility of the tests can be reliably evaluated.

Systematic review with meta-analysis: loss of response and requirement of anti-TNFα dose intensification in Crohn's disease

BACKGROUND

To review the frequency with which anti-TNF-α loses its effect and dose "intensification" is required for Crohn's disease (CD) treatment.

METHODS

Electronic databases were searched for eligible studies. Raw data from studies meeting inclusion criteria were pooled for effect estimates. Subgroup analyses were performed for exploration of heterogeneity regarding all outcomes.

RESULTS

Eighty-six eligible studies were included. Estimates of loss of response (LOR) incidence ranged from 8 to 71%. The random effects pooled incidence of LOR with a median follow-up of 1-year was 33% (95% CI 29-38, 55 studies, n = 6135). The effect estimate based on data from patients with infliximab was 33% (95% CI 27-40), 30% (95% CI 22-39) for adalimumab, and 41% (95% CI 30-53) for certolizumabpegol. Overall, the mean percentage of patients' LOR to anti-TNFs was 38.5%. The annual risk for LOR was 20.9% per patient-year. The random-effects pooled rate of need for dose intensification with a median follow-up of 1 year was 34% (95% CI 28-41, 38 studies, n = 10,690). The effect estimate for infliximab was 38% (95% CI 28-50), 36% (95% CI 30-43) for adalimumab, and 2% (95% CI 2-3) for certolizumab-pegol. The mean percentage of patients who needed an anti-TNF dose escalation was 23% with an annual risk of 18.5% per patient-year. There was no evidence of publication bias for incidence of LOR but not for the dose intensification (p = 0.001).

CONCLUSIONS

Overall, around one-third of CD patients experience a LOR and required dose intensification in primary anti-TNF-α responders.

Clinical correlations of infliximab trough levels and antibodies to infliximab in South Korean patients with Crohn’s disease

AIM

To investigate the clinical implications of infliximab trough levels (IFX-TLs) and antibodies to infliximab (ATI) levels in Crohn’s disease (CD) patients in Asian countries.

METHODS

IFX-TL and ATI level were measured using prospectively collected samples obtained with informed consent from CD patients being treated at Asan Medical Center, South Korea. We analyzed the correlations between IFX-TLs/ATI levels and the clinical activity of CD (quiescent vs active disease) based on the CD activity index, C-reactive protein level, and physician’s judgment of patients’ clinical status at enrollment. The impact of concomitant immunomodulators was also investigated.

RESULTS

This study enrolled 138 patients with CD (84 with quiescent and 54 with active disease). In patients with quiescent and active diseases, the median IFX-TLs were 1.423 μg/mL and 0.163 μg/mL, respectively (P < 0.001) and the median ATI levels were 8.064 AU/mL and 11.209 AU/mL, respectively (P < 0.001). In the ATI-negative and -positive groups, the median IFX-TLs were 1.415 μg/mL and 0.141 μg/mL, respectively (P < 0.001). In patients with and without concomitant immunomodulator use, there were no differences in IFX-TLs (0.632 μg/mL and 1.150 μg/mL, respectively; P = 0.274) or ATI levels (8.655 AU/mL and 9.017 AU/mL, respectively; P = 0.083).

CONCLUSION

IFX-TL/ATI levels were well correlated with the clinical activity in South Korean CD patients. Our findings support the usefulness of IFX-TLs/ATI levels in treating CD patients receiving IFX in clinical practice.

Detection of anti-infliximab antibodies is impacted by antibody titer, infliximab level and IgG4 antibodies: a systematic comparison of three different assays

BACKGROUND

There is scant information on the accuracy of different assays used to measure anti-infliximab antibodies (ADAs), especially in the presence of detectable infliximab (IFX). We thus aimed to evaluate and compare three different assays for the detection of IFX and ADAs and to clarify the impact of the presence of circulating IFX on the accuracy of the ADA assays.

METHODS

Blood samples from 79 ulcerative colitis (UC) patients treated with infliximab were assessed for IFX levels and ADAs using three different assays: an in-house assay and two commercial kits, Immundiagnostik and Theradiag. Sera samples with ADAs and undetectable levels of IFX were spiked with exogenous IFX and analyzed for ADAs.

RESULTS

The three assays showed 81-96% agreement for the measured IFX level. However, the in-house assay and Immundiagnostik assays detected ADAs in 34 out of 79 samples, whereas Theradiag only detected ADAs in 24 samples. Samples negative for ADAs with Theradiag, but ADA-positive in both the in-house and Immundiagnostik assays, were positive for IFX or IgG4 ADAs. In spiking experiments, a low concentration of exogenous IFX (5 µg/ml) hampered ADA detection with Theradiag in sera samples with ADA levels of between 3 and 10 µg/ml. In the Immundiagnostik assay detection interference was only observed at concentrations of exogenous IFX higher than 30 µg/ml. However, in samples with high levels of ADAs (>25 µg/ml) interference was only observed at IFX concentrations higher than 100 µg/ml in all three assays. Binary (IFX/ADA) stratification of the results showed that IFX+/ADA- and IFX-/ADAs+ were less influenced by the assay results than the double-positive (IFX+/ADAs+) and double-negative (IFX-/ADAs-) combination.

CONCLUSIONS

All three methodologies are equally suitable for measuring IFX levels. However, erroneous therapeutic decisions may occur when patients show double-negative (IFX-/ADAs-) or double-positive (IFX+/ADAs+) status, since agreement between assays is significantly lower in these circumstances.

Adalimumab trough serum levels and anti-adalimumab antibodies in the long-term clinical outcome of patients with Crohn's disease

OBJECTIVE

Few data are available on the relevance of adalimumab (ADA) trough serum levels and anti-ADA antibodies (AAA) during long-term follow-up of patients with Crohn's Disease (CD), and their association with disease outcome. In this study, our aim was to assess ADA trough serum levels and the presence of AAA according to disease activity and clinical response during long-term follow-up in a series of patients with CD treated with ADA monotherapy.

MATERIAL AND METHODS

We prospectively evaluated 23 consecutive, infliximab-naïve CD patients who achieved clinical remission/response after induction and were in maintenance treatment with ADA, and who were followed-up for at least 72 weeks. Blood samples were drawn at standardized time points to assess ADA through levels, AAA.

RESULTS

At week 48, we found significantly (p = 0.027) different ADA trough serum levels in patients in remission (10.1 mcg/mL), mild (7.4 mcg/mL), and moderate/severe disease (4.5 mcg/mL). Median ADA trough levels were significantly lower in patients with AAA (3.7 mcg/mL versus 9.3 mcg/mL, p = 0.006). At the end of follow-up (median 102 weeks, range 73-112 weeks), ADA trough serum concentrations were significantly higher (11.9 mcg/mL) as compared to patients with mild and moderate/severe disease (5.5 mcg/mL, p = 0.0002). Furthermore, median ADA trough concentrations showed a trend towards lower levels in AAA positive patients (5.2 mcg/mL versus 7.2 mcg/mL, p = 0.371).

CONCLUSIONS

Our results emphasize the relevance of therapeutic drug monitoring in CD patients on biologic treatment. ADA trough serum levels and the presence of AAA are important features in the management of patients on ADA treatment.

A Systematic Review on Infliximab and Adalimumab Drug Monitoring: Levels, Clinical Outcomes and Assays

BACKGROUND

Immunogenicity to therapeutic proteins has been linked to loss of response by a large percentage of patients taking anti-tumor necrosis factor-alpha agents. Drug monitoring can be extremely useful, allowing physicians to adjust the therapeutic scheme individually. This article aims to systematically review the published data with respect to cutoff levels of infliximab (IFX) and adalimumab (ADA) and relate them to the methodology adopted for quantification of IFX and ADA levels and clinical outcomes.

METHODS

The PubMed database was searched to identify studies focusing on the association between IFX or ADA cutoff levels and clinical outcomes in patients with inflammatory bowel disease.

RESULTS

Of the 1654 articles initially selected by queries, 20 were included. A receiver operating characteristic curve analysis was performed to identify cutoff levels of IFX or ADA that correlated with a clinical outcome, but only 6 studies performed the same analysis for antidrug antibody levels. Cutoff levels were different between studies. The methodology chosen for level quantifications, clinical outcomes, and sample size and characteristics were also different. Nevertheless, measurement of drug levels should be performed during maintenance, and with loss of response, with persistent high levels of C-reactive protein, and when mucosal lesions are still present. In these scenarios, drug and antidrug levels were correlated with clinical outcomes.

CONCLUSIONS

Concerning drug levels monitoring any methodology is adequate. With respect to antidrug antibody levels, it will be necessary to define a gold standard method or to establish different cutoff levels for different methodologies.

Prediction of clinical and endoscopic responses to anti-tumor necrosis factor-α antibodies in ulcerative colitis

Objective In patients with ulcerative colitis (UC), the relationship between the initial endoscopic findings and the response to anti-tumor necrosis factor (TNF)-α antibodies remains unclear. We herein evaluated the potential of endoscopic assessment using the ulcerative colitis endoscopic index of severity (UCEIS) to predict the response to anti-TNF-α antibodies. Methods We enrolled 64 patients with UC undergoing anti-TNF-α maintenance therapy with infliximab (IFX) or adalimumab (ADA) between April 2010 and March 2015. Anti-TNF-α trough levels were determined by ELISA. Endoscopic disease activity was assessed using the UCEIS. Results The clinical response rate at 8 weeks was 77.4% for IFX and 66.7% for ADA. Serum albumin levels were significantly higher and the UCEIS bleeding descriptor before treatment was significantly lower in the responders than in the non-responders (p < 0.05 each). The CRP levels at 2 weeks were significantly lower in the responders (p < 0.001). The serum albumin levels before treatment were significantly higher and the UCEIS erosions and ulcers descriptor was significantly lower in the mucosal healing group than in the non-mucosal healing group (p < 0.05 each). A significant and negative correlation between the trough levels of anti-TNF-α antibodies and the UCEIS descriptors was observed. The trough levels of anti-TNF-α antibodies to achieve mucosal healing were 2.7 μg/mL for IFX and 10.3 μg/mL for ADA. Conclusions The UCEIS score, as well as some clinical markers (serum albumin and CRP levels), is useful for the prediction of the treatment outcome of UC patients in response to anti-TNF-α antibodies.

Clinical Pharmacokinetics and Pharmacodynamics of Monoclonal Antibodies Approved to Treat Rheumatoid Arthritis

Monoclonal antibodies (mAbs) are increasingly used to treat rheumatoid arthritis (RA). At present, anti-tumor necrosis factor-α drugs (infliximab, adalimumab, certolizumab pegol, and golimumab), rituximab, and tocilizumab are approved for RA treatment. This review focuses on the pharmacokinetics and pharmacodynamics of mAbs approved in RA. Being large proteins, mAbs exhibit complex pharmacokinetic and pharmacodynamic properties. In particular, owing to the interactions of mAbs with their antigenic targets, the pharmacokinetics of mAbs depends on target turnover and exhibits non-specific (linear) and target-mediated (often nonlinear) clearances. Their volume of distribution is low (3-4 L) and their elimination half-life usually ranges from 2 to 3 weeks. The inter-individual pharmacokinetic variability of mAbs is usually large and is partly explained by differences in antigenic burden or by anti-drug antibodies, which accelerate mAb elimination. The inter-individual variability of clinical response is large and influenced by the pharmacokinetics. The analysis of mAbs concentration-effect relationship relies more and more often on pharmacokinetic-pharmacodynamic modeling; these models being suitable for dosing optimization. Even if adverse effects of mAbs used in RA are well known, the relationship between mAb concentration and adverse effects is poorly documented, especially for anti-tumor necrosis factor-α mAbs. Overall, RA patients treated with mAbs should benefit from individualized dosing strategies. Because of the complexity of their pharmacokinetics and mechanisms of action, the current dosing strategy of mAbs is not based on sound knowledge. New studies are needed to assess individual dosing regimen, adjusted notably to disease activity.

Therapeutic strategy for Crohn's disease with a loss of response to infliximab: a single-center retrospective study

BACKGROUND/AIMS

Infliximab (IFX) is an effective treatment for maintaining clinical remission in patients with initially moderate-to-severe Crohn's disease (CD). However, a certain number of patients become unresponsive to IFX, subsequently requiring intensified therapy. The aim of this study was to compare the short- and long-term therapeutic efficacy of intensified regimens in CD patients who fail to respond to IFX.

METHODS

The clinical courses of 33 CD patients who failed to respond to treatment with IFX were investigated retrospectively. An intensified regimen involving doubling the dose of IFX was chosen in 13 patients (DD group) versus shortening the IFX interval in 13 patients (SI group) and switching to adalimumab (ADA) in 7 patients (SA group).

RESULTS

The clinical response and rate of clinical remission at 4 weeks were 62 and 54% in the DD group, 77 and 62% in the SI group and 57 and 43% in the SA group, respectively (p = 0.59 for clinical response, p = 0.90 for clinical remission). The rate of sustained remission at 48 weeks was 44% in the DD group, 54% in the SI group and 33% in the SA group (p = 0.88).

CONCLUSION

The short- and long-term efficacy of doubling the dose of IFX, shortening the interval of IFX or switching to ADA is similar for CD patients who no longer respond to IFX.

Antibodies to infliximab are associated with lower infliximab levels and increased likelihood of surgery in pediatric IBD

BACKGROUND

Adult studies suggest antibodies to infliximab (ATI) correlate with loss of response in inflammatory bowel disease but pediatric data are limited.

METHODS

We conducted a cross-sectional study of trough infliximab levels and ATI in 134 pediatric and young adult patients receiving infliximab. At the time serum was obtained demographics, disease phenotype, duration of infliximab therapy, use of combination therapy (methotrexate or 6-mercaptopurine with infliximab), and surgery were recorded.

RESULTS

Assays were performed on 134 subjects currently receiving infliximab (85 male; mean age, 17.3 ± 4.3 years; 114 Crohn's disease and 20 ulcerative colitis). Infliximab use ranged from 12 days to 12 years: median 2.0 (interquartile range [1.1-4.3]) years. Twenty-seven of 134 (20%) patients had ATI ≥5 U/mL. Of patients with ATI ≥5 U/mL, 59% had infliximab levels <5 μg/mL, compared with 14% of patients with ATI <5 U/mL (P < 0.001). Ten (7%) patients (9 Crohn's disease, 1 ulcerative colitis) underwent bowel resections after beginning infliximab infusions. Sixty percent who underwent surgery had ATI ≥12 U/mL; in contrast, only 8% of patients who did not undergo surgery had ATI ≥12 U/mL (P = 0.01). At the time of serum sampling, 50 (37%) patients were receiving combination therapy, compared with 84 (63%) on infliximab alone. Combination therapy at the time of serum sampling did not correlate with either increase infliximab levels or lower ATI compared with infliximab monotherapy. However, prior immunomodulator use was associated with lower antibody levels (P = 0.007).

CONCLUSIONS

ATI correlates with reduction in infliximab level and a higher risk of surgery in patients with inflammatory bowel disease.

Role for therapeutic drug monitoring during induction therapy with TNF antagonists in IBD: evolution in the definition and management of primary nonresponse

: Primary nonresponse and primary nonremission are important limitations of tumor necrosis factor (TNF) antagonists, occurring in 10% to 40% and 50% to 80% of patients with inflammatory bowel disease, respectively. The magnitude of primary nonresponse differs between phase III clinical trials and cohort studies, indicating differences, e.g., in definition, patient population or blinding. The causes of nonresponse can be attributed to the drug (pharmacokinetics, immunogenicity), the patient (genetics, disease activity), the disease (type, location, severity), and/or the treatment strategy (dosing regimen, combination therapy). Primary nonresponse has been attributed to "non-TNF-driven disease" which is an overly simplified and potentially misleading approach to the problem. Many patients with primary nonresponse could successfully be treated with dose optimization during the induction phase or switching to another TNF antagonist. Therefore, primary nonresponse is frequently not a non-TNF-driven disease. Recent studies from rheumatoid arthritis and preliminary data from inflammatory bowel disease evaluating therapeutic drug monitoring have suggested that early measurement of drug and anti-drug antibody concentrations could help to define primary nonresponse and rationalize patient management of this problem. Moreover, a modeling approach including pharmacological parameters and patient-related covariants could potentially be predictive for response to the treatment. We describe an overview of this evolution in thinking, underpinned by previous findings, and assess the potential role of early measurement of drug and antidrug antibody concentrations in the definition and management of primary nonresponse.

Therapeutic drug monitoring in inflammatory bowel disease: current state and future perspectives

Current available anti-inflammatory drugs, in particular monoclonal antibodies directed against the cytokine tumor necrosis factor α (TNF), have greatly enhanced the treatment of inflammatory bowel diseases (IBD). Although many patients respond to ant-TNF therapy, a proportion of patients will not respond (primary non-response) or will lose response to the drug over time (secondary non-response). This loss of response can be caused by patient, TNF-inhibitor, or disease-related factors influencing the pharmacokinetics and pharmacodynamics of the drug. Therefore, monitoring pharmacological parameters (i.e. therapeutic drug monitoring) may help guide therapeutic decisions. This review emphasizes interesting and important new findings, and provides an updated overview, on the subject of therapeutic drug monitoring. While exploring the hypothesis that "one size does not fit all", we focused on the first prospective studies investigating the novel approach in IBD of 'target concentration adjusted dosing' and personalized medicine.

Trough s-infliximab and antibodies towards infliximab in a cohort of 79 IBD patients with maintenance infliximab treatment

BACKGROUND AND AIMS

The anti-TNF antibody infliximab is effective in inducing remission in Crohn's disease as well as in ulcerative colitis and many patients are treated for several years with sustained clinical remission. However, the role of monitoring s-infliximab and antibodies towards infliximab during maintenance treatment remains unclear. Our aim was to correlate serum drug levels and antibodies to clinical activity, CRP, albumin and concomitant immunosuppression in a cohort on maintenance infliximab treatment.

METHODS

We included 79 patients with Crohn's disease or ulcerative colitis who had responded to infliximab and received maintenance treatment (4-69 infusions) in this retrospective study. Infliximab levels and antibodies towards the drug were analyzed with in-house-developed ELISA assays.

RESULTS

The mean s-infliximab was significantly higher in patients in remission (4.1μg/mL) as compared with disease flare (mean 1.8μg/mL); p<0.001. The s-infliximab showed a significant negative correlation with Harvey-Bradshaw index (r=-0.21; p<0.05). Serum-infliximab progressively decreased with the number of accumulated infusions (p<0.05). In patients with undetectable trough levels, 55% of the patients with concomitant immunosuppressive were positive for antibodies against infliximab, as compared with 94% of patients on monotherapy. Patients with undetectable serum-infliximab were in clinical remission at 25% of the visits.

CONCLUSIONS

The trough level 4.1μg/mL may serve as cut-off for clinical remission. Drug trough levels decreased during treatment and almost all patients with undetectable s-infliximab and monotherapy had developed antibodies against the drug.

Biologic therapies in inflammatory bowel disease

Inflammatory bowel disease, including its 2 entities ulcerative colitis and Crohn's disease, is a chronic medical condition characterized by the destructive inflammation of the intestinal tract. Biologics represent a class of therapeutics with immune intervention potential. These agents block the proinflammatory cascade that triggers the activation and proliferation of T lymphocytes at the level of the intestine, therefore reestablishing the balance between the pro- and anti-inflammatory messages. All 7 biologics showing clinical benefits in inflammatory bowel disease are monoclonal antibodies. The following systematic review discusses the pharmacokinetics and efficacy of the tumor necrosis factor blockers infliximab, adalimumab, certolizumab pegol, and golimumab. In addition, we describe the α4 integrin inhibitors natalizumab and vedolizumab, which are directed against cell adhesion molecules, as well as the interleukin 12/23 blocker ustekinumab.

A prospective cohort study to determine the relationship between serum infliximab concentration and efficacy in patients with luminal Crohn's disease

BACKGROUND

Patients with Crohn's disease (CD) may experience disease relapse on maintenance infliximab. Anti-drug antibodies likely contribute to loss of response, and serum infliximab levels likely correlate with efficacy.

AIM

To prospectively evaluate the relationship between trough serum infliximab concentration and disease activity.

METHODS

Adult patients (N = 327) with a diagnosis of CD who had received at least five consecutive infliximab infusions and who planned to receive at least two additional infusions were enrolled. The Crohn's Disease Activity Index (CDAI), serum infliximab, C-reactive protein (CRP) and antibodies-to-infliximab (ATI) were assessed at baseline, week 4 and week 8. Receiver operating characteristic (ROC) analysis examined the relationship between infliximab concentrations and disease activity.

RESULTS

The mean CDAI score, which decreased 1.05 points between infusions, did not correlate with the mean change in trough infliximab concentration (+0.39 μg/mL; r = 0.099, P = 0.083), but was associated with the mean change in CRP concentration (r = 0.19, P < 0.001). Trough infliximab concentrations below 2.8-4.6 μg/mL best predicted a ≥ 70 point increase in the CDAI between infusions, and those below 2.7-2.8 μg/mL best predicted CRP >5 mg/mL at the second infusion. ATI at either visit decreased the proportion of patients with therapeutic infliximab trough levels compared with patients who were ATI negative (17.5% vs. 77.3% at visit 1 and 13.8% vs. 75.6% at visit 3; P < 0.001 for both comparisons).

CONCLUSIONS

This prospective study confirms the relationship between trough infliximab concentrations, inflammation and antibodies-to-infliximab. Infliximab trough concentrations below 3 μg/mL may increase the likelihood of symptoms and inflammation (ClinicalTrials.gov identifier: NCT00676988).

Relationship between serum infliximab trough levels and endoscopic activities in patients with Crohn's disease under scheduled maintenance treatment

BACKGROUND AND AIMS

Few data are available to support the clinical relevance of infliximab (IFX) trough levels for prediction of endoscopic disease activity in Crohn's disease (CD). This study evaluated the endoscopic disease activities in relation to clinical outcome using several laboratory markers including serum IFX trough levels in patients with CD undergoing scheduled IFX maintenance treatment.

MATERIALS AND METHODS

A total of 78 sessions of endoscopy were performed on 45 patients with CD. Endoscopic activity was assessed using the modified Rutgeerts scoring system. IFX trough levels and anti-IFX antibodies (ATIs) were determined by immunoassays.

RESULTS

Endoscopic activity negatively correlated with serum IFX trough levels (Spearman's rank correlation coefficient (ρ) = -0.54, P < 0.0001) and serum albumin levels (ρ = -0.46, P < 0.0001), and positively correlated with CRP (C-reactive protein) levels (ρ = 0.55, P < 0.0001), ESR (erythrocyte sedimentation rate) (ρ = 0.47, P < 0.0001) and fecal calprotectin levels. IFX trough levels and serum albumin levels were significantly elevated in the mucosal healing (MH) group, but ATIs, CRP, ESR and fecal calprotectin levels were significantly elevated in the nonmucosal healing group. Receiver operation curve revealed that the optimal cutoff value of IFX trough levels for identifying normal laboratory markers was 0.6 μg/ml for CRP, 1.0 μg/ml for serum albumin and 1.1 μg/ml for fecal calprotectin. Identification of mucosal healing needed a higher cutoff value of 4.0 μg/ml. Thiopurine treatment did not affect IFX trough and ATI levels.

CONCLUSION

Mucosal healing requires higher IFX trough levels, compared to those to achieve normalization of routine clinical markers.

Characterization of gut microbiota profiles by disease activity in patients with Crohn's disease using data mining analysis of terminal restriction fragment length polymorphisms

The gut microbiota plays a significant role in the pathogenesis of Crohn’s disease (CD). In this study, we analyzed the disease activity and associated fecal microbiota profiles in 160 CD patients and 121 healthy individuals. Fecal samples from the CD patients were collected during three different clinical phases, the active (n=66), remission-achieved (n=51) and remission-maintained (n=43) phases. Terminal restriction fragment length polymorphism (T-RFLP) and data mining analysis using the Classification and Regression Tree (C&RT) approach were performed. Data mining provided a decision tree that clearly identified the various subject groups (nodes). The majority of the healthy individuals were divided into Node-5 and Node-8. Healthy subjects comprised 99% of Node-5 (91 of 92) and 84% of Node-8 (21 of 25 subjects). Node-3 was characterized by CD (136 of 160 CD subjects) and was divided into Node-6 and Node-7. Node-6 (n=103) was characterized by subjects in the active phase (n=48; 46%) and remission-achieved phase (n=39; 38%) and Node-7 was characterized by the remission-maintained phase (21 of 37 subjects; 57%). Finally, Node-6 was divided into Node-9 and Node-10. Node-9 (n=78) was characterized by subjects in the active phase (n=43; 55%) and Node-10 (n=25) was characterized by subjects in the remission-maintained phase (n=16; 64%). Differences in the gut microbiota associated with disease activity of CD patients were identified. Thus, data mining analysis appears to be an ideal tool for the characterization of the gut microbiota in inflammatory bowel disease.

Comparison of techniques for monitoring infliximab and antibodies against infliximab in Crohn's disease

BACKGROUND

Several techniques are used to measure infliximab (IFX) and anti-IFX antibodies (Abs) in Crohn's disease. The aim of this study was to compare different assays for this purpose.

METHODS

Fluid-phase radioimmunoassay (RIA), solid-phase enzyme-linked immunosorbent assay (ELISA), reporter gene assay (RGA), and enzyme immunoassay (EIA; anti-IFX Ab only) were assessed. IFX was added to pooled serum from 13 patients with inactive Crohn's disease to yield concentrations of 0, 1, 3, and 9 µg/mL. Anti-IFX Abs were assessed in 6 patients.

RESULTS

IFX assessments: RIA and RGA had lower limit of detection than ELISA (0.07 µg/mL and 0.13 versus 0.26). Maximal inaccuracies were 39%, 24%, and 23%. Imprecisions (coefficients of variation) were ≤20% within IFX concentrations between 1 and 9 µg/mL. All assays showed linear correlations (R = 0.97-0.99), but sample concentrations differed by up to 1.55 µg/mL for RIA and RGA, 1.41 µg/mL for ELISA and RIA, and 0.48 µg/mL for ELISA and RGA (P < 0.05). Anti-IFX Ab assessments: RGA gave highly reproducible results (coefficients of variation ≤ 7%) compared with all others (24%-26%). All assays had linear correlations (R = 0.71-0.93), except ELISA versus RGA and EIA. Assays disagreed on anti-IFX Ab titers with mean difference -420 (-1200 to 210) in RGA and EIA, and up to 4500 (-2700 to 11,800) in RIA and RGA. A contributing factor to these discrepancies was inability of ELISA to detect IgG4 anti-IFX Abs.

CONCLUSIONS

Performances of assays for IFX and anti-IFX Abs are comparable. However, IFX concentrations and anti-IFX Ab titers show systematic differences, and in individual patients, only the same assay should be used. Problems may arise when different assays are used to manage therapies in the same patient.

Outcomes following infliximab therapy for pediatric patients hospitalized with refractory colitis-predominant IBD

OBJECTIVES

Although randomized trials demonstrated the efficacy of infliximab for both pediatric Crohn disease and ulcerative colitis (UC), few patients in these studies exhibited colitis requiring hospitalization. The aims of this study were to determine the rate of subsequent infliximab failure and dose escalation in pediatric patients who started taking infliximab during hospitalization for colitis-predominant IBD, and to identify potential predictors of these endpoints.

METHODS

This is a single-center retrospective cohort study of patients admitted from 2005 to 2010 with Crohn colitis, UC, or IBD-unspecified (IBD-U) and initiated on infliximab.

RESULTS

We identified 29 patients (12 Crohn colitis, 15 UC, and 2 IBD-U; median age 14 years) with a median follow-up of 923 days. Eighteen patients (62%) required infliximab dose escalation (increased dose or decreased infusion interval). Infliximab failure occurred in 18 patients (62%) because of ineffectiveness in 12 (67%) and adverse reactions in 6 (33%). Twelve patients (41%) underwent colectomy. Subsequent need for infliximab dose escalation was associated with lower body mass index z score (P = 0.01), lower serum albumin (P = 0.03), and higher erythrocyte sedimentation rate (ESR) (P = 0.002) at baseline. ESR predicted subsequent infliximab dose escalation with an area under the curve of 0.89 (95% confidence interval [CI] 0.72-1.00) and a sensitivity and specificity at a cutoff of 38 mm/hour of 0.79 (95% CI 0.49-0.95) and 0.88 (95% CI 0.47-0.99), respectively.

CONCLUSIONS

Most hospitalized pediatric patients with colitis treated with infliximab require early-dose escalation and fail the drug long term. Low body mass index and albumin and high ESR, may identify patients who would benefit from a higher infliximab starting dose.

Clinical utility of newly developed immunoassays for serum concentrations of adalimumab and anti-adalimumab antibodies in patients with Crohn's disease

BACKGROUND/AIM

The appearance of anti-adalimumab antibodies (AAAs) is associated with low serum adalimumab (ADA) trough levels and a decrease of clinical response. The goal of this study was to assess the accuracy and clinical utility of new immunoassays for serum ADA and AAA levels.

PATIENTS AND METHODS

Serum ADA trough levels and AAA levels were measured using new immunoassays in 40 patients with Crohn's disease (CD) receiving ADA maintenance therapy.

RESULTS

Serum ADA trough levels were 12.3 ± 9.6 μg/ml (n = 40) in CD patients, and 14 of 40 patients (35 %) were positive for AAAs. A negative correlation was observed between serum AAA levels and ADA trough levels (y = -6.02x + 18.7, r = -0.54, P < 0.001, n = 40). The ROC (receiver-operator curve) analyses indicated that an ADA trough of 5.9 μg/ml was optimal to maintain negative CRP (C-reactive protein) levels (≤0.3 mg/dl). The ADA trough levels were significantly lower in patients positive for AAAs (5.5 ± 5.4 μg/ml, n = 14) than in patients negative for AAAs (16.0 ± 9.5 μg/ml, n = 26). The CRP and ESR levels were significantly higher in AAA-positive patients than in AAA-negative patients. Serum albumin levels were significantly lower in AAA-positive patients. The positive rate for AAAs in patients who lost a response to infliximab (50 %) was significantly higher than that of anti-TNF-α drug naïve patients (12.5 %).

CONCLUSIONS

These new assays for serum AAA trough and AAA levels are useful for routine clinical use and may help guide selection of optimal management strategies for IBD patients with a loss of response to ADA.

Hepatitis B virus reactivation induced by infliximab administration in a patient with Crohn's disease

A 47-year-old man diagnosed with Crohn's disease was treated with infliximab. He tested negative for hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs) but positive for anti-HB core antibody (anti-HBc). He tested positive for hepatitis B virus (HBV-) DNA 3 months after treatment and was administered entecavir. HBV-DNA test showed negative results 1 month later. ALT was persistently within the normal range, and HBV-DNA was persistently negative thereafter despite the continuation of infliximab every 8 weeks. In our hospital, 14 patients with inflammatory bowel disease, who tested negative for HBsAg, were treated with infliximab; 2 of them tested positive for anti-HBs and/or anti-HBc, and HBV reactivation was observed in 1 patient (the present patient). The present case and these findings highlight that careful follow-up is needed in patients with inflammatory bowel disease treated with infliximab who test positive for anti-HBc and/or anti-HBs.

Impact of antibodies to infliximab on clinical outcomes and serum infliximab levels in patients with inflammatory bowel disease (IBD): a meta-analysis

OBJECTIVES

Antibodies to infliximab (ATIs) have been associated with loss of clinical response and lower serum infliximab (IFX) levels in some studies of patients with inflammatory bowel disease (IBD). This has important implications for patient management and development of novel biologic therapies. The objective of this study was to perform a systematic review and meta-analysis of studies that reported clinical outcomes and IFX levels according to patients' ATI status.

METHODS

MEDLINE, Web of Science, CINAHL, Scopus, and EMBASE were searched for eligible studies. Quality assessment was undertaken using GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria. Raw data from studies meeting inclusion criteria was pooled for meta-analysis of effect estimates. Sensitivity analysis was performed for all outcomes. Funnel plot was performed to assess for publication bias.

RESULTS

Thirteen studies met the inclusion criteria, and reported results in 1,378 patients with IBD. All included studies had a high risk of bias in at least one quality domain. The pooled risk ratio (RR) of loss of clinical response to IFX in patients with IBD who had ATIs was 3.2 (95% confidence interval (CI): 2.0-4.9, P<0.0001), when compared with patients without ATIs. This effect estimate was predominantly based on data from patients (N=494) with Crohn's disease (RR: 3.2, 95% CI: 1.9-5.5, P<0.0001). Data only from patients with ulcerative colitis (n=86) exhibited a non-significant RR of loss of response of 2.2 (95% CI: 0.5-9.0, P=0.3) in those with ATIs. Heterogeneity existed between studies, in both methods of ATI detection, and clinical outcomes reported. Three studies (n=243) reported trough serum IFX levels according to ATI status; the standardized mean difference in trough serum IFX levels between groups was -0.8 (95% CI -1.2, -0.4, P<0.0001). A funnel plot suggested the presence of publication bias.

CONCLUSIONS

The presence of ATIs is associated with a significantly higher risk of loss of clinical response to IFX and lower serum IFX levels in patients with IBD. Published studies on this topic lack uniform reporting of outcomes. High risk of bias was present in all the included studies.

Immunosuppression in inflammatory bowel disease: how much is too much?

PURPOSE OF REVIEW

Current treatment approaches favor the early introduction of immunomodulators and/or antitumor necrosis factor (TNF) agents. There is now strong evidence showing that combination therapy appears to be more effective than monotherapy in both ulcerative colitis and Crohn's disease. However, there are concerns associated with this strategy, and eventually the following questions will emerge when discussing therapeutic options with our patients: is it safe to maintain these therapies for the long-term?; how long should we maintain therapy?; and if we decide to stop or de-escalate therapy, what strategy should we use?

RECENT FINDINGS

During the past year new evidence regarding safety of long-term therapy with anti-TNF and immunomodulators, and predictors of relapse following therapy discontinuation have become available.

SUMMARY

In this review we aim to discuss some of the safety concerns related to the use of immunosuppressive drugs used in inflammatory bowel disease, as well as the possible strategy for de-escalation or discontinuation therapy. Eventually, choosing to stop either the anti-TNF or the immunomodulator is a case-by-case decision based on the estimated risk-benefit ratio. In addition to the identified predictors of relapse after therapy discontinuation, other considerations such as long-term safety, cost, and natural history of the disease must be brought into this discussion.

Development and validation of a homogeneous mobility shift assay for the measurement of infliximab and antibodies-to-infliximab levels in patient serum

Antibody-based drugs such as infliximab (IFX) are effective for the treatment of inflammatory bowel disease (IBD) and other immune-mediated disorders. The development of antibodies against these drugs may result in unfavorable consequences, including the loss of drug efficacy, hypersensitivity reactions, and other adverse events. Therefore, accurate monitoring of serum drug and anti-drug antibody levels should be an important part of therapy for patients being treated with an antibody-based drug. Current methods for the assessment of anti-drug antibodies and drug levels, involving various bridging ELISA and radioimmunoassay techniques, are limited by their sensitivity, interference, and/or complexity. To overcome these limitations, we have developed a non-radiolabeled homogeneous mobility shift assay (HMSA) to measure the antibodies-to-infliximab (ATI) and IFX levels in serum samples. Full method validation was performed on both the ATI- and IFX-HMSA, and the clinical sample test results were also compared with those obtained from a bridging ELISA method to evaluate the difference in performance between the two assays. Validation of the ATI-HMSA revealed a lower limit of quantitation of 0.012 μg/mL in serum. The linear range of quantitation was 0.029-0.54 μg/mL. The intra- and inter-assay precision was less than 20% of coefficient of variation (CV), and the accuracy (% error) of the assay was less than 20%. In serum samples, ATI as low as 0.036 μg/mL can be measured, even in the presence of 60 μg/mL of IFX in the serum. Sera from 100 healthy subjects were tested to determine the cut point of the assay. ATI-positive samples that had been previously analyzed by using a bridging ELISA from 100 patients were also measured by the new method. There was a high correlation between the two methods for ATI levels (p<0.001). Significantly, the new method identified five false-positive samples from the bridging ELISA method. Validation of the mobility shift IFX assay also showed high assay sensitivity, precision and accuracy. The HMSA method may also be applied to other protein-based drugs to accurately detect serum drug and anti-drug antibody levels.