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

Comparative study of a point-of-care test and an enzyme-linked immunosorbent assay (ELISA) for infliximab levels

BACKGROUND

Proactive therapeutic drug monitoring (TDM) is often challenged by long turnaround time when using enzyme-linked immunosorbent assays (ELISAs), especially when analyses are centralised. Point-of-care tests (POCTs) allow rapid assessments, but data on their agreement with existing in-house methodologies are scarce.

OBJECTIVE

To examine the agreement between a POCT by ProciseDx (San Diego, CA) and the most frequently used in-house ELISA for infliximab (IFX) quantification in Sweden.

METHODS

Serum samples were analysed using the in-house ELISA, Karolinska University Hospital, Stockholm, Sweden and a POCT by ProciseDx (San Diego, CA). Agreement was assessed and differences were examined.

RESULTS

Samples from 61 inflammatory bowel disease (IBD) patients were analysed with a median IFX concentration of 7.9 μg/mL (interquartile range (IQR) 5.5-13) for the POCT and 7.9 μg/mL (IQR 5.2-12) for the ELISA (Pearson's correlation coefficient = 0.95 (95% CI 0.92-0.97, p < .01)). A Passing-Bablok regression yielded an intercept of -0.44 and a slope of 1.09. The Bland-Altman plot showed a systemic bias of -0.77 μg/mL (95% CI -0.18 to -1.4) between the methods. The upper limit of agreement was 3.7 (95% CI 2.7-4.8) (μg/mL), whereas the lower limit agreement was -5.3 (95% CI -6.3 to -4.3) (μg/mL). An excellent reliability was observed, intraclass correlation showed = 0.94 (95% CI 0.89-0.96, p < .0001). When defining IFX concentration as subtherapeutic (<3.0 μg/mL), therapeutic (3.0-7.0 μg/mL) or supratherapeutic (>7.0 μg/mL) drug levels, Kappa statistics showed a substantial agreement (0.79).

CONCLUSIONS

The POCT by ProciseDx (San Diego, CA) demonstrated a good agreement with the in-house ELISA, supporting its use for rapid IFX quantification.

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

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

Infliximab trough levels are associated with endoscopic healing but not with transmural healing at one year treatment with infliximab in pediatric patients with Crohn's disease

Introduction

It is well known that infliximab (IFX) trough levels (TLs) are associated with endoscopic healing (EH) in Crohn's disease (CD). We investigated whether IFX TLs are associated with transmural healing (TH) in pediatric patients with CD following 1-year treatment.

Methods

Pediatric patients with CD treated with IFX were included in this single-center prospective study. IFX TL tests, magnetic resonance enterography (MRE), and colonoscopies were simultaneously conducted after 1-year IFX treatment. TH was defined as a wall thickness of ≤3 mm without inflammatory signs evaluated using MRE. EH was defined as a Simple Endoscopic Score for Crohn's disease of <3 points on colonoscopy.

Results

Fifty-six patients were included. EH and TH were observed in 60.7% (34/56) and 23.2% (13/56) of patients, respectively. IFX TLs were higher in patients with EH (median, 5.6 vs. 3.4 µg/mL, P = 0.002), whereas IFX TLs showed no significant difference in patients with and without TH (median, 5.4 vs. 4.7 µg/mL, P = 0.574). No significant difference was observed in EH and TH between patients whose intervals were shortened or not. Multivariate logistic regression analysis showed that IFX TLs and disease duration to IFX initiation were associated with EH (odds ratio [OR] = 1.82, P = 0.001, and OR = 0.43, P = 0.02, respectively).

Discussion

In pediatric patients with CD, IFX TLs were associated with EH but not with TH. Further studies investigating long-term TH and proactive dosing based on therapeutic drug monitoring may clarify whether an association between IFX TLs and TH exists.

Free antibodies-to-infliximab are biomarker for predicting the effect of dose intensification in pediatric Crohn's disease patients with secondary loss of response

Background

Immunogenicity to antitumor necrosis factor alpha agents, such as infliximab (IFX), may lead to therapeutic failure.

Objectives

This study evaluated the relationship between free and total antibodies-to-infliximab (ATIs), trough levels (TLs) of IFX, and the response to dose intensification.

Design

We performed a prospective, observational study including pediatric patients with Crohn's disease (CD) receiving IFX maintenance therapy without dose intensification.

Methods

We compared clinical and laboratory outcomes according to the presence of free and total ATIs. Factors associated with response to IFX dose intensification were investigated by analyzing IFX TLs and free and total ATIs.

Results

Of the 98 patients, 9 patients had detectable free ATIs and 38 patients had total ATIs. Patients with free ATIs had significantly lower TLs (0.7 versus 5.1 µg/mL, p < 0.001) than patients without free ATIs. However, there was no difference in the IFX TLs according to the presence of total ATIs (p = 0.2523). Analysis of the 38 samples with total ATIs showed that response to dose intensification was significantly lower in patients with free ATIs than those without free ATIs (22.2% versus 65.5%, p < 0.001). In addition, free ATIs were the only factor with poor response to dose intensification [odds ratio (OR): 14.15, 95% confidence interval (CI): 1.31-151.97, p = 0.0140]. According to the receiver operating characteristic analysis, the optimal cutoff level indicating non-response to IFX dose intensification was 30.0 AU/mL for free ATIs concentration (area under curve, 0.792; 95% CI: 0.590-0.942; sensitivity, 60.0%; specificity, 96.7%; p = 0.0241).

Conclusion

Free ATIs, but not total ATIs, have a negative impact on the course of CD. Free ATIs are potential reliable biomarker for predicting the effect of dose intensification in patients with loss of response to IFX. Future studies based on serial and proactive therapeutic drug monitoring are required in the future.

The inhibitory effect of oral administration of lentinan on DSS-induced inflammation is exerted by the migration of T cells activated in the ileum to the colon

Oral administration of lentinan ameliorated dextran sulfate sodium (DSS)-induced colitis through Dectin-1 receptor on intestinal epithelial cells. However, it is unclear where lentinan affects in the intestine to prevent the inflammation. We found that the administration of lentinan has induced migration of CD4+ cells from the ileum to the colon by using Kikume Green-Red (KikGR) mice in this study. This result suggests that the oral lentinan treatment could accelerate the migration of Th cells in lymphocyte from ileum into the colon during lentinan intake. Then, C57BL/6 mice were administered 2% DSS to induce colitis. The mice were administered lentinan daily via oral or rectal route before DSS administration. Its rectal administration also suppressed DSS-induced colitis, but its suppressive effects were lower compared to when orally administered, indicating that the biological responses to lentinan in the small intestine contributed to the anti-inflammatory effects. In normal mice (without DSS treatment), the expression of Il12b was significantly increased in the ileum by the oral administration of lentinan, but not by rectal one. On the other hand, no change was observed in the colon by either administration method. In addition, Tbx21 was significantly increased in the ileum. These suggested that IL-12 was increased in the ileum and Th1 cells differentiated in dependence on it. Therefore, Th1 predominant condition in the ileum could influence immunity in the colon and improve the colitis.

THE EVALUATION OF INFLIXIMAB TROUGH LEVEL FAVORS MAINTENANCE THERAPY OF PATIENTS WITH INFLAMMATORY BOWEL DISEASE

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are chronic diseases that result from the deregulation of the mucosal immune system of the gastrointestinal tract. The use of biological therapies, including infliximab (IFX), is one of the strategies to treat both CD and UC. The IFX treatment is monitored by complementary tests, namely: fecal calprotectin (FC); C-reactive protein (CRP); and endoscopic and cross-sectional imaging. Besides, serum IFX evaluation and antibody detection are also used.

OBJECTIVE

To evaluate trough levels (TL) and antibodies in a population with inflammatory bowel (IBD) disease undergoing treatment with IFX, and the factors that might impact the treatment effectiveness.

METHODS

Retrospective, cross-sectional study with patients with IBD that were assessed for TL and antibody (ATI) levels in a southern Brazilian hospital, from June 2014 to July 2016.

RESULTS

The study assessed 55 patients (52.7% female) submitted to serum IFX and antibody evaluations (95 blood samples, 55 first test; 30 second test, and 10 as third testing. Forty-five (47.3%) cases were diagnosed with CD (81.8%), and ten with UC (18.2%). Serum levels were adequate in 30 samples (31.57%), subtherapeutic in 41 (43.15%), and supratherapeutic in 24 (25.26%). IFX dosages were optimized for 40 patients (42.10%), maintained for 31 (32.63%), and discontinued for 7 (7.60%). The intervals between infusions were shortened in 17.85% of the cases. In 55 tests (55.79%), the therapeutic approach was exclusively defined according to IFX and/or serum antibody levels. The assessment of patients one year later indicated that: the approach was maintained with IFX for thirty-eight patients (69.09%); the class of biological agent was changed for eight (14.54%); changes using the same class of biological agent occurred for two patients (3.63%); the medication was discontinued and not replaced for three patients (5.45%), and four patients (7.27%) were lost to follow-up.

CONCLUSION

There were no differences in TL between groups with or without immunosuppressants, serum albumin (ALB), erythrocyte sedimentation rate (ESR), FC, CRP, and endoscopic and imaging examinations. Current therapeutic approach could be maintained for almost 70% of patients. Thus, serum and antibody levels are a useful tool in the follow-up of patients undergoing maintenance therapy and after treatment induction in patients with inflammatory bowel disease.

Utility, promise, and limitations of liquid chromatography-mass spectrometry-based therapeutic drug monitoring in precision medicine

Therapeutic drug monitoring (TDM) is typically referred to as the measurement of the concentration of drugs in patient blood. Although in the past, TDM was restricted to drugs with a narrow therapeutic range in order to avoid drug toxicity, TDM has recently become a major tool for precision medicine being applied to many more drugs. Through compensating for interindividual differences in a drug's pharmacokinetics, improved dosing of individual patients based on TDM ensures maximum drug effectiveness while minimizing side effects. This is especially relevant for individuals that present a particularly high intervariability in pharmacokinetics, such as newborns, or for critically/severely ill patients. In this article, we will review the applications for and limitations of TDM, discuss for which patients TDM is most beneficial and why, examine which techniques are being used for TDM, and demonstrate how mass spectrometry is increasingly becoming a reliable and convenient alternative for the TDM of different classes of drugs. We will also highlight the advances, challenges, and limitations of the existing repertoire of TDM methods and discuss future opportunities for TDM-based precision medicine.

Impact of infliximab therapeutic drug level monitoring on outcomes of patients with inflammatory bowel disease: A real-world experience from a Middle Eastern cohort

BACKGROUND AND STUDY AIM

Therapeutic drug monitoring (TDM) through measurement of infliximab (IFX) trough levels and antibodies to infliximab (ATI) is performed to guide IFX intensification strategies and improve its efficacy. We conducted this study to explore the relationship between clinical and endoscopic/radiological remission and IFX and ATI levels in patients with inflammatory bowel disease (IBD) treated with IFX and to evaluate the appropriateness of treatment decision post TDM.

PATIENTS AND METHODS

This was a cross-sectional study of a cohort of adult patients with IBD. Serum IFX trough concentrations and ATI were measured.

RESULTS

A total of 129 patients [104] with ulcerative colitis (UC) and 25 with Crohn's disease (CD)] were included in this study, of whom 61.2% were men. The mean disease duration was 6.7 years, and 72% of patients with UC had extensive colitis. The mean serum IFX trough level was 4.1 µg/mL; the IFX trough levels were subtherapeutic in 75 patients (58%), therapeutic in 37 patients (29%), and supratherapeutic in 17 patients (13%). Positivity to ATI was found in 16 patients (12.4%). Only 43 patients (33.3%) underwent an appropriate change in therapy after TDM, patients with penetrating CD disease had low IFX levels and higher C-reactive protein levels at 12 months before TDM.

CONCLUSIONS

Patients with IBD with therapeutic IFX levels tend to have increased endoscopic/radiological remission rates. However, an appropriate change in management based on TDM was absent in the majority of patients, potentially reflecting the need to have a dashboard to support and guide clinicians in decision-making.

Drug Tolerant Anti-drug Antibody Assay for Infliximab Treatment in Clinical Practice Identifies Positive Cases Earlier

A subgroup of patients treated with infliximab lose response to the treatment and one reason for this is the development of anti-drug antibodies (ADA). If used optimally, measuring drug and ADA level could lead to a more personalized and efficient treatment regime, and enable identification of ADA-positive patients before the underlying disease flares or allergic reactions occur. With the use of a drug-tolerant ADA assay which can detect ADA irrespective of drug levels in the sample, we determined the impact of ADA on treatment failure to infliximab. The aims of this study were to estimate the real-life optimal serum infliximab (sIFX) level and set a clinical threshold value for a drug-tolerant ADA assay. Trough levels of sIFX were measured with ELISA. Free ADA was measured with two drug-sensitive methods (ELISA and a bioassay) and one drug-tolerant method (PandA). Two real-life cohorts treated with infliximab were included; a cross-sectional cohort including patients with inflammatory rheumatic diseases (n = 270) and a prospective cohort of rheumatoid arthritis (RA) patients (n = 73) followed for 1 year. Normal range of sIFX was estimated from the prospective cohort and an arbitrary optimal drug level was set to be between 1 and 6 μg/mL. Using this range, optimal sIFX was found in only 60% (163/270) of the patients in the cross-sectional cohort. These patients had significantly better treatment response than those with a drug level under 1 μg/mL, who had an ADA frequency of 34% (19/56) using the drug-tolerant method. In the prospective cohort, the drug-tolerant assay could identify 34% (53/155 samples) as ADA positive in samples with sIFX level >0.2 μg/mL. ADA were seldom detected in patients with >1 μg/mL sIFX, with three interesting exceptions. A clinically relevant ADA threshold was determined to be >3 RECL as measured with the drug-tolerant assay. In a real-life setting, there was a substantial number of patients with suboptimal drug levels and a proportion of these had ADA. Both too low and too high drug levels correlated with worse disease, but for different reasons. Adding a drug-tolerant assay enabled detection of ADA earlier and regardless of drug level at time of sampling.

Usefulness of monitoring antitumor necrosis factor serum levels during the induction phase in patients with Crohn's disease

AIMS

The aims of this study were (a) to know the kinetics of antitumor necrosis factor (TNF) drug serum levels during the induction phase in patients with Crohn's disease; (b) to identify variables associated with these levels; and (c) to assess the relation between these levels and short-term effectiveness in Crohn's disease patients.

METHODS

Patients with Crohn's disease naïve to anti-TNF treatment were prospectively included. Remission was defined as a Crohn's disease activity index (CDAI) score <150 after 14 weeks of treatment. Blood samples were obtained at baseline and at weeks 4, 8, and 14. Adalimumab and infliximab levels were measured, receiver operating characteristic (ROC) curves were constructed, and the area under the ROC curve was calculated.

RESULTS

One-hundred fifty patients with Crohn's disease were included, 79 (53%) received infliximab and 71 (47%) had CDAI > 150 at study entry. At week 14, 52 out of 71 patients with CDAI > 150 at baseline (73%) had clinical remission. There were no differences in infliximab levels between patients with and without remission (8 vs. 9.1 μg/mL, P > 0.05) or with and without response (7 vs. 11 μg/mL, P > 0.05) at week 14. There was a trend to higher levels of adalimumab concentration in responders in comparison with nonresponders (13 vs. 6.7 μg/mL, P = 0.05) and in patients who achieved remission in comparison with nonremitters (13.5 vs. 8.4 μg/mL, P = 0.06). In the multivariate analysis, no variable was predictive of short-term remission, including infliximab and adalimumab serum levels.

CONCLUSION

Determining anti-TNF serum levels during the induction phase is not useful for predicting short-term remission in patients with Crohn's disease.

Review article: determination of the therapeutic range for therapeutic drug monitoring of adalimumab and infliximab in patients with inflammatory bowel disease

BACKGROUND

Clinical application of therapeutic drug monitoring (TDM) to optimise anti-TNF therapies in patients with IBD depends upon target ranges.

AIMS

To review methodology used to determine therapeutic ranges and critically compare and contrast its application to infliximab and adalimumab.

METHODS

A systematic review was performed, and relevant literature was summarised and critically examined.

RESULTS

Upper limits of the therapeutic range are determined by toxicity, a plateau response and cost. Lower limits are determined by optimal concentration on the target of action in vitro and/or in vivo, or by correlation of drug levels with clinical efficacy using area-under-receiver-operator-curve (AUROC) analysis. In 43 studies, there were huge variations in time at which infliximab and adalimumab levels were measured, the end-points used (clinical remission to mucosal healing), the clinical setting (active disease vs maintenance phase) and the reason for TDM (proactive vs reactive). In the maintenance phase for infliximab, lower trough limits 2.8-5.7 µg/mL are reported depending upon end-points used, with consistent AUROC 0.68-0.77. Adalimumab TDM targets are even less consistent with a lower limit 5.9-11.8 µg/mL (AUROC 0.66-0.83) in some studies, but no cut-off can be identified that is significantly associated with outcome in others, related to inherent pharmacokinetic and pharmacodynamic differences, and heterogeneity of study design.

CONCLUSIONS

Evidence for exposure-response relationship is stronger for infliximab than adalimumab. Due to heterogeneity in settings for drug level measurements, therapeutic ranges vary. These factors need to be taken into account when interpreting the evidence and extending this to therapeutic strategies for IBD patients.

Appropriate Therapeutic Drug Monitoring of Biologic Agents for Patients With Inflammatory Bowel Diseases

BACKGROUND & AIMS

Therapeutic drug monitoring (TDM) is widely available for biologic therapies in patients with inflammatory bowel disease (IBD). We reviewed current data and provided expert opinion regarding the clinical utility of TDM for biologic therapies in IBD.

METHODS

We used a modified Delphi method to establish consensus. A comprehensive literature review was performed regarding the use of TDM of biologic therapy in IBD and presented to international IBD specialists. Subsequently, 28 statements on the application of TDM in clinical practice were rated on a scale of 1 to 10 (1 = strongly disagree and 10 = strongly agree) by each of the panellists. Statements were accepted if 80% or more of the participants agreed with a score ≥7. The remaining statements were discussed and revised based on the available evidence followed by a second round of voting.

RESULTS

The panel agreed on 24 (86%) statements. For anti-tumor necrosis factor (anti-TNF) therapies, proactive TDM was found to be appropriate after induction and at least once during maintenance therapy, but this was not the case for the other biologics. Reactive TDM was appropriate for all agents both for primary non-response and secondary loss of response. The panellists also agreed on several statements regarding TDM and appropriate drug and anti-drug antibody (ADA) concentration thresholds for biologics in specific clinical scenarios.

CONCLUSION

Consensus was achieved towards the utility of TDM of biologics in IBD, particularly anti-TNF therapies. More data are needed especially on non-anti-TNF biologics to further define optimal drug concentration and ADA thresholds as these can vary depending on the therapeutic outcomes assessed.

Association of female sex and positive rheumatoid factor with low serum infliximab and anti-drug antibodies, related to treatment failure in early rheumatoid arthritis: results from the SWEFOT trial population

Objective: Infliximab-treated patients with rheumatoid arthritis (RA) may respond insufficiently due to low serum infliximab (sIFX) levels, caused by anti-drug antibodies (ADAs). However, monitoring of sIFX and ADAs is not routinely implemented, and levels for optimal outcome have not been validated. We searched for predictors for sIFX < 0.2 μg/mL and ADA development in a randomized setting. Methods: In the SWEFOT trial, of 128 patients randomized to methotrexate + IFX therapy, 101 had serum samples at 3, 9, and 21 months that were analysed for sIFX [enzyme-linked immunosorbent assay (ELISA)] and ADAs [ELISA, and precipitation and acid dissociation (PandA) when sIFX > 0.2 μg/mL]. The primary and secondary outcome measures were low disease activity [LDA = 28-joint Disease Activity Score (DAS28) ≤ 3.2] and remission (DAS28 < 2.6). Baseline characteristics were assessed as potential predictors of sIFX < 0.2 μg/mL or ADA positivity, using logistic regression. Results: Categorization of sIFX levels into < 0.2, 0.2-2.9, 3.0-7.0, and > 7.0 μg/mL showed a dose-response association with LDA (30%, 64%, 67%, and 79%, respectively, p = 0.008) and remission (10%, 45%, 39%, and 66%, p = 0.004) at trial cessation (21 months). Female patients had sIFX < 0.2 μg/mL more often than males (35% vs 7%, p = 0.006), with a similar trend for rheumatoid factor (RF)-positive vs RF-negative patients (34% vs 16%, p = 0.059). ADA positivity showed similar patterns, also after adjustment for potential confounders (female sex: p = 0.050; RF positivity: p = 0.067). PandA captured four highly ADA-reactive patients with sIFX > 0.2 μg/mL, of whom three were ADA positive at other time-points, all with high DAS28 at follow-up. Conclusion: In early RA patients receiving IFX as a second-line agent, sIFX < 0.2 μg/mL and ADA development were associated with treatment failure and were more common in females, with a similar trend for RF positivity. Our findings support the use of therapeutic drug monitoring, and PandA in ADA-negative non-responders. Trial registration: SWEFOT NCT00764725 ( https://clinicaltrials.gov/ct2/show/NCT00764725 ).

Switching from originator infliximab to the biosimilar CT-P13 in 313 patients with inflammatory bowel disease

BACKGROUND

As the patents of originator biologics are expiring, biosimilar versions are becoming available for the treatment of inflammatory bowel disease (IBD). However, published switch studies of the first infliximab biosimilar, CT-P13, have delivered ambiguous results that could be interpreted as showing a trend towards inferior effectiveness in Crohn's disease (CD) compared with ulcerative colitis (UC). The aim of this study was to investigate the effectiveness and safety of switching IBD patients from treatment with Remicade to CT-P13.

METHODS

In this prospective observational cohort study, all adult IBD patients on Remicade treatment, at four hospitals, were switched to CT-P13. The primary endpoint was change in clinical disease activity at 2, 6, and 12 months after the switch. Secondary endpoints were subgroup analyses of patients with and without concomitant immunomodulators; changes in biomarkers, quality of life, drug trough levels and anti-drug antibodies (ADAbs); and adverse events.

RESULTS

A total of 313 IBD patients were switched (195 CD; 118 UC). There were no significant changes in clinical disease activity, quality of life, biomarkers (except a small but significant increase in albumin in CD) including F-calprotectin, drug trough levels, or proportion of patients in remission. Disease worsening rates were 14.0% for CD and 13.8% for UC; and 2.7% developed ADAbs and 2.2% developed serious adverse events.

CONCLUSIONS

This is the largest study of switched IBD patients published to date, and it demonstrates that switching from Remicade to CT-P13 may be done with preserved therapeutic effectiveness and safety in both CD and UC.

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.

Subtherapeutic concentrations of infliximab and adalimumab are associated with increased disease activity in Crohn's disease

BACKGROUND

Low anti-tumor necrosis factor α (TNFα) serum concentrations may result in lack of treatment response in patients with inflammatory bowel disease. We determined the anti-TNFα drug concentrations in patients with inflammatory bowel disease and investigated whether or not subtherapeutic drug concentrations were associated with increased levels of disease activity.

METHODS

In a single-center cross-sectional study, we included patients with ulcerative colitis or Crohn's disease who were receiving infliximab or adalimumab maintenance therapy. Demographic data, disease activity symptom scores (Partial Mayo Score, Harvey Bradshaw Index), inflammatory markers [C-reactive protein (CRP), fecal calprotectin], antidrug antibodies and serum drug concentrations were recorded. Therapeutic drug concentrations were defined as 3-8 mg/liter for infliximab and 5-12 mg/liter for adalimumab.

RESULTS

Of 210 patients included, 137 (65.2%) had Crohn's disease. In the adalimumab group, subtherapeutic drug concentrations were measured in 16.7% of patients with ulcerative colitis and in 27.7% of patients with Crohn's disease. In the infliximab group, subtherapeutic drug concentrations were found in 23% (ulcerative colitis) and 30.3% (Crohn's disease) of patients. In Crohn's disease, subtherapeutic adalimumab concentrations were associated with higher fecal calprotectin and CRP concentrations compared with therapeutic concentrations. Subtherapeutic infliximab concentrations in patients with Crohn's disease were also associated with higher CRP concentrations compared with therapeutic concentrations.

CONCLUSIONS

The prevalence of subtherapeutic drug levels ranged from 17% to 30%. In patients with Crohn's disease, subtherapeutic serum drug concentrations were associated with significantly higher disease activity with both anti-TNFα agents. These findings were not observed in patients with ulcerative colitis. Clinicaltrials.gov identifier [NCT02134054].

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.

Evaluation of Infliximab Therapy in Children with Crohn's Disease Using Trough Levels Predictors

BACKGROUND

In adults, infliximab (IFX) levels correlate with disease activity, and antibodies to IFX (ATIs) predict treatment failure. We aimed to determine the association of IFX levels and ATIs with disease activity in a paediatric population. We prospectively collected blood, stool, and clinical data from 65 patients (age 10.5-15.1 years) with Crohn's disease (CD) before IFX administration, and measured IFX trough levels, ATIs, and faecal calprotectin levels (CPT). Samples were collected during maintenance therapy. We used multivariate analysis to identify the predictors of IFX levels.

SUMMARY

Lower levels of IFX were associated with ATIs positivity (OR 0.027, 95% CI 0.009-0.077). Higher C-reactive protein (CRP) level, erythrocyte sedimentation rate, and CPT levels were found in patients with lower IFX levels. The optimal combination of sensitivity (0.5) and specificity (0.74) for disease activity was calculated for IFX levels ≥1.1 µg/mL using CRP level <5 mg/L as a marker of laboratory remission. In a model that used CPT ≤100 µg/g as the definition of remission, the optimal IFX trough level was 3.5 µg/mL. No independent association between remission and ATIs was found in our study population. However, we found an independentz association between IFX levels and serum albumin levels (OR 1.364, 95% CI 1.169-1.593), p < 0.001. Key Messages: The paediatric population was similar to adult populations in terms of the association between IFX and ATIs as well as between IFX and disease activity.

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.

Proposal for an anti-TNF-exit strategy based on trough serum level

BACKGROUND AND AIMS

The aim of the study was to evaluate, if the strategy to stop anti-TNF treatment after determination of low trough serum levels and exclusion of inflammation is associated with lower relapse rates.

METHODS

Since 2013 we followed an exit strategy in patients treated with anti-TNF treatment for inflammatory bowel disease based on trough serum levels. The relapse rates were observed prospectively, data analysis was performed in a retrospective manner of the collected clinical data.

RESULTS

Forty patients were enrolled, who stopped anti-TNF therapy. 13 Patients followed the clinical algorithm, 27 patients were used as control group (13 patients with ulcerative colitis and 14 patients with Crohn's disease). 19 patients received Infliximab, 21 Adalimumab. The median follow-up time after discontinuation was 19 months (IQR 18). Relapses were observed in 22/40 patients (55%). Among the 13 patients with a targeted discontinuation of therapy based on the algorithm, three relapses were observed (23%), compared to 19/27 (70%) from the non-algorithm group (OR: 7.9; 95%-CI: 1.7-36.5). Relapse-free-survival after anti-TNF discontinuation was significantly higher in patients treated by the algorithm compared to the non-algorithm group (p = 0.032).

CONCLUSION

An exit strategy based on trough serum levels significantly reduces the relapse rate.

Serum-Infliximab Trough Levels in 45 Children with Inflammatory Bowel Disease on Maintenance Treatment

The role of trough serum infliximab (s-IFX) and antibodies toward IFX (ATI) during maintenance treatment remains unclear in children. The aim of the present study was to investigate trough s-IFX and ATI to identify any correlation with inflammatory activity and clinical response in a pediatric inflammatory bowel disease (IBD) cohort. We investigated the s-IFX trough levels in pediatric IBD patients (n = 45) on maintenance IFX treatment. Ninety-three blood samples were collected and demographics, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and albumin were recorded. The mean s-IFX trough level was 5.2 µg/mL. The mean trough s-IFX level was significantly higher in the samples taken during remission (7.2 µg/mL) compared to active disease (4.5 µg/mL, p < 0.05). The trough s-IFX levels correlated with ESR, CRP, and albumin. S-IFX was undetectable in eight of the patients, all with positive ATI and active disease. Surprisingly, clinical and biochemical remission was observed at only 26 of the 93 visits. The correlation between dose variations and changes in trough s-IFX was not evident. In line with studies in adults, the s-IFX trough levels correlated with response to infliximab.

Clinical impact of immunomonitoring in the treatment of inflammatory bowel disease

Despite improvement in outcomes, loss of response (LOR) to tumor necrosis factor-alpha (TNFα) therapies is a big concern in the management of inflammatory bowel disease. LOR is associated with flares of disease, increased hospitalisation rates, need for surgical interventions, and decline in quality of life. LOR may be multifactorial, but immunogenicity makes a significant contribution. Traditionally doses of anti-TNFα have been adjusted based on clinical response, using a standard approach. Immunomonitoring involves the measurement of anti-TNFα trough and antibody levels. It takes into account the underlying pharmacokinetics of anti-TNFα therapies. Expanding on this a treat to target approach may be used, where doses are intensified, or tailored to the individual based on the measurement of anti-TNFα trough and antibody levels. This review looks at the history, evolution, and clinical impact that immunomonitoring is having in the treatment of inflammatory bowel disease. It will focus on the role of immunomonitoring in helping to achieve long lasting deep remission and mucosal healing. It will explore the different options in terms of best measuring trough and antibody levels, explore possible advantages of immunomonitoring, and discuss its role in best optimising response, at induction, during the maintenance phase of treatment, as well as a role in withdrawing or switching therapy.

Therapeutic Drug Monitoring and Clinical Outcomes in Immune Mediated Diseases: The Missing Link

As the incidence of inflammatory bowel diseases and the number of patients treated with anti-TNF agents keep on increasing so are the phenomena of primary non response (PNR) and secondary loss of response (SLR) to these medications. Traditionally PNR and SLR have been managed empirically-that is, switching medications for PNR and increasing the anti-TNF dose for SNR. More recently an approach based on testing drug levels and antibodies to the drug (therapeutic drug monitoring) has gained increasing popularity in the management of inflammatory bowel diseases. However, while this strategy might offer an insight into the mechanisms leading to PNR/SLR it often falls short of providing a simple, reproducible method to manage these issues in clinical practice. Here, we will review the currently recommended therapeutic strategies when using therapeutic drug monitoring; the evidence for and against such approach and the current standard strategies in Rheumatology (the specialty with the largest and longest experience with anti-TNF agents). We will then discuss the possible reasons of the shortcomings of therapeutic drug monitoring and the rationale and need to move the therapeutic target to the disease burden in inflammatory bowel diseases-along with the supporting preliminary evidence. Finally, we will focus on future crucial studies that need to be done to make approaches to PNR/SLR more rigorous and at the same time user-friendly for the practicing gastroenterologist.

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.

Emerging therapeutic targets and strategies in Crohn's disease

Crohn's disease (CD) is an immune-mediated inflammatory bowel disease, in which inflammation is driven by a complex interaction between the microbiota, immune cells, genes and mediators. New mechanisms of action and several cytokines have been identified as factors involved in the inflammatory process in CD, and many new molecules have been developed to treat this complex disease. New agents have been developed that target leukocyte trafficking, block or adhesion molecules for example, as well as the development of antibodies against classic inflammatory cytokines or therapies directed against IL-12/23 and Janus kinases. The development of selective mechanisms of action and targeting of different cytokines or inflammatory mediators for each patient presents the biggest challenge for the future in CD therapy. Such agents are currently at different phases of development. We aim to review the current literature data on a targeted approach in CD, which could be promising alternative approach for CD patients in the near future.

Serum Infliximab, Antidrug Antibodies, and Tumor Necrosis Factor Predict Sustained Response in Pediatric Crohn's Disease

BACKGROUND

Serum infliximab (s-IFX) levels, antibodies to IFX (ATI), and inflammatory markers are important in predicting clinical outcomes in adults, but their roles in pediatric Crohn's disease (CD) require further study. The primary aim of this study was to determine the association between serologic parameters during induction and ongoing IFX therapy at 12 months in pediatric CD.

METHODS

S-IFX, ATI, serum tumor necrosis factor alpha (s-TNF-α), and C-reactive protein were measured at IFX initiation, 10 weeks, 6 months, and 12 months in a prospective cohort study of children with CD at a single tertiary care center.

RESULTS

At 12 months, 60 of 77 participants (78%) remained on IFX. Participants who completed 12 months of IFX had higher 10-week median s-IFX levels (20.40 μg/mL; interquartile range [IQR], 11.20-35.00] versus 8.70 μg/mL; IQR 0.90-16.90; P = 0.01), a greater proportion with undetectable 10-week ATI (P = 0.008), and a greater median change in s-TNF-α between baseline and week 10 (-5.96 pg/mL; IQR, -8.73 to -4.17 versus -1.76 pg/mL; IQR, -5.60 to 0.30; P = 0.006). Receiver operating characteristic analysis to predict ongoing IFX at 12 months showed area under the curve (95% confidence interval) for 10-week s-IFX and change in s-TNF-α from baseline to 10 weeks to be 0.71 (0.54-0.88) and 0.74 (0.58-0.91), respectively. C-reactive protein was not associated with ongoing therapy.

CONCLUSIONS

ATI, s-IFX, and s-TNF-α during IFX induction are associated with 12-month clinical outcomes in pediatric CD. Future studies are needed to further define the clinical role of s-TNF-α measurement and to compare the clinical utility of 10 and 14-week ATI and s-IFX levels.

Practical Use of Infliximab Concentration Monitoring in Pediatric Crohn Disease

OBJECTIVES

Therapeutic drug monitoring (TDM) that guides infliximab (IFX) intensification strategies has been shown to improve IFX efficacy. We conducted a review to evaluate the utility of TDM in the assessment and subsequent management of IFX loss of response in our pediatric population with Crohn disease (CD).

METHODS

Single-center retrospective study of patients with CD receiving IFX that had TDM from December 2009 to September 2013. We defined subtherapeutic trough as a drug level below the detection limit of the Prometheus enzyme-linked immunoabsorbant assay and Anser reference values (1.4 and 1 μg/mL, respectively) or a mid-interval level <12 μg/mL.

RESULTS

One hundred ninety-one IFX concentration tests were performed on 72 patients with CD with loss of response to therapy as the primary indication (72%). 34% of all TDM were subtherapeutic. After initial TDM, 25 of the 72 patients received regimen intensification with 72% in clinical remission at 6 months. Including all of the TDM that resulted in IFX dose intensification, we found a significant improvement in 6-month remission rates whether intensification followed mid-interval (88% remission) or trough (56% remission) testing (P = 0.026). Antibody to infliximab was found in 14 patients with 5 occurring in the first year of therapy. Furthermore, 71% of patients with antibody to infliximab that were switched to an alternative anti-tumor necrosis factor achieved clinical remission at six months. In multivariable regression analysis, we found IFX dose (mg/kg), IFX dosing frequency (weeks), and the erythrocyte sedimentation rate at the previous infusion were significantly associated with the IFX concentration.

CONCLUSIONS

TDM in our pediatric population with CD led to informed clinical decisions and improved rates of clinical remission.

Anti-TNF drug and antidrug antibody level monitoring in IBD: a practical guide

The antitumour necrosis factor (TNF) medications, adalimumab and infliximab, play an important role in the management of both Crohn's disease and ulcerative colitis. For those in whom anti-TNF is effective, the therapy is associated with fewer symptoms, improved quality of life and disease and surgery-free survival. Unfortunately, up to 30% of patients will fail to respond to anti-TNF drugs while up to 50% of those who do see an initial response will lose response at some point. The introduction of drug monitoring for anti-TNFs, including drug level and antidrug antibody level testing allows a more personalised management of patients and improves patient outcomes. This article reviews the data for the use of anti-TNF monitoring and presents a 'how to' guide for clinicians.

The association of infliximab trough levels with disease activity in pediatric inflammatory bowel disease

OBJECTIVE

Low serum trough levels (TLs) of infliximab (IFX) and antibodies to IFX (ATIs) are associated with the loss of therapeutic response in adults with inflammatory bowel disease (IBD) receiving IFX. Until now, pediatric data are scarce. Therefore, we aimed to cross-sectionally investigate the association between ATIs and IFX TLs, and clinical and biochemical disease activity in children receiving IFX for IBD.

MATERIAL AND METHODS

Children aged <18 years receiving IFX maintenance treatment for Crohn's disease (CD) or ulcerative colitis (UC) at three Dutch hospitals were included. Prior to two consecutive IFX infusions, IFX TLs and ATI levels were measured. Clinical disease activity was determined by Pediatric Crohn's Disease Activity Index (PCDAI) and Pediatric Ulcerative Colitis Activity Index (PUCAI), for CD and UC, respectively. Biochemical disease activity was assessed by serum C-reactive protein (CRP) and fecal calprotectin (FC). Clinical remission was defined as a PUCAI or PCDAI score of <10. Therapeutic range of IFX was considered 3-7 µg/ml.

RESULTS

Thirty-nine patients were included (31 CD; 16 females). Median age was 15 years. Median IFX TL was 3.5 µg/ml [IQR 2-7]. Subtherapeutic and supratherapeutic TLs were found in 38% and 23% of children, respectively. ATIs were detected in four patients. A correlation was found between IFX TL and CRP [rs = -0.51; p < 0.01] and FC [rs = -0.49; p < 0.01]. However, when only clinical disease activity was considered, no difference in median TL was found between remission and active disease (resp. 3.5 µg/ml [IQR 2-5] and 2.3 µg/ml [IQR 0.3-4.6]; p = 0.2).

CONCLUSIONS

IFX TLs are related to biochemical markers of disease activity. This could provide a rationale for monitoring TLs in children receiving IFX for IBD.

Clinical relevance and inter-test reliability of anti-infliximab antibodies and infliximab trough levels in patients with inflammatory bowel disease

BACKGROUND

Treatment with infliximab is a common option for inflammatory bowel disease (IBD) patients. Therapeutic drug monitoring could improve treatment management.

AIMS

To test inter-test reliability of two commercially available diagnostic kits for infliximab trough levels and infliximab antibodies, and their association with treatment outcomes.

METHODS

86 IBD outpatients on infliximab maintenance treatment were enrolled in a prospective cross-sectional study, 115 samples were available for inter-test reliability.

RESULTS

Inter-test agreement was good both for trough levels (concordance correlation coefficient 0.78, weighted κ 0.60, Sperman's ρ 0.937) and for infliximab antibodies (weighted κ 0.79) measurement, when comparing Promonitor and ImmunDiagnostik kits. According to manufacturers' cut-off values, trough levels were classified as undetectable (17%), low (21%) or in range (63%). The only significant associations were: mucosal healing (p=0.026; OR 6.50), infliximab antibody status (p=0.0015; OR 0.031) and adverse events (p=0.009; OR 0.115). Higher trough levels were observed among patients on concomitant steroid/immunosuppressive therapy and among patients with dose-intensification. Infliximab antibodies were significantly associated to treatment-related adverse events (p=0.0003, OR 30.42), and to lower trough levels, but not to other clinical variables.

CONCLUSION

The two tests performed equally well. Infliximab antibodies were associated to adverse events, while trough levels were not associated to treatment outcomes.

Therapeutic drug monitoring is predictive of loss of response after de-escalation of infliximab therapy in patients with inflammatory bowel disease in clinical remission

BACKGROUND

There is no evidence that therapeutic drug monitoring is helpful in patients with inflammatory bowel disease patients in clinical remission with infliximab therapy.

METHODS

Eighty consecutive inflammatory bowel disease patients in clinical remission on infliximab maintenance therapy were included and followed-up for at least one year. Infliximab trough level and antibody to infliximab concentration were measured prior to enrollment. At the time of enrollment, physicians in charge were free to alleviate infliximab therapy. Discrepancies between blind and therapeutic drug monitoring-based adjustments were assessed at the end of the follow-up period. Relapse-free survival was analyzed using univariate and multivariate analyses.

RESULTS

The mean infliximab trough level was 3.1 μg/mL. Antibody to infliximab was found in 15 (19%) patients. At the end of the follow-up period, 18 (22.5%) patients experienced a relapse. The 3, 6, 9 and 12-month relapse-free rates were 98%, 87%, 86% and 80%, respectively. In our multivariate analysis, relapse-free survival was negatively associated with discrepancies between therapeutic drug monitoring-based and blind adjustments of infliximab therapy, absence of concomitant immunomodulator, the absence of mucosal healing, prior use of infliximab, infliximab therapy duration>2 years and C-reactive protein levels>5mg/L at the time of enrollment.

CONCLUSION

In patients with inflammatory bowel disease in clinical remission on infliximab therapy, de-escalation of infliximab therapy should be considered based on therapeutic drug monitoring rather than according to symptoms and CRP.

IgE antibodies and skin tests in immediate hypersensitivity reactions to infliximab in inflammatory bowel disease: impact on infliximab retreatment

BACKGROUND

Infliximab (IFX) is used for the treatment of inflammatory bowel diseases (IBD). Immediate hypersensitivity reactions (HR) to IFX are frequently reported.

OBJECTIVES

We investigated immunoglobulin E (IgE)-mediated mechanisms underlying immediate HR to IFX. We also evaluated the clinical utility of allergological tests as well as the tolerability of IFX retreatment in these patients.

METHODS

This was a prospective single-center study including IBD patients with previous immediate HR to IFX. Skin tests to IFX, including prick tests and intradermal tests, and measurement of anti-IFX IgE antibodies were performed at least 4 weeks after HR. In case of negative skin tests and absence of IgE antibodies, readministration of IFX was performed with a twice-reduced infusion rate. In case of positive tests or recurrence of HR during readministration of IFX, a 12-step desensitization or induction of tolerance protocol was proposed.

RESULTS

A total of 24 IBD patients were included (Crohn's disease: n=20). Prick tests to IFX were all negative. Intradermal test was positive in one patient. Anti-IFX IgE antibodies were not detected in 21 patients and were detected in three patients (significant level in one patient and intermediate level in two patients). No relationship was observed between positive skin tests and the presence of anti-IFX IgE antibodies. Switch to adalimumab was well tolerated in 10/11 patients. The readministration of IFX was well tolerated in 4/11 patients. Desensitization to IFX was successful in three out of four patients.

CONCLUSION

The vast majority of immediate HR to IFX is not IgE-mediated. Allergological tests are of poor clinical utility. Desensitization or induction of tolerance protocol may allow continuation of IFX therapy in IBD patients with a history of immediate HR.

Successful Treatment with Infliximab for Refractory Uveitis in a Hemodialysis Patient with Behçet's Disease and a Review of the Literature for Infliximab Use in Patients on Hemodialysis

A 36-year-old man with a 16-year history of refractory Behçet's disease (BD)-associated uveitis and chronic renal failure requiring hemodialysis suffered from frequent ocular attacks despite treatment with systemic corticosteroids and cyclosporine A. Following infliximab administration, the patient's BD ocular attack score 24 and visual acuity improved. Although he developed mild acute gastroenteritis, he did not experience any other adverse events. In our review of the literature, we identified seven patients on hemodialysis with inflammatory disease successfully treated with infliximab. Infliximab may be effective and safe in cases of BD and other diseases, including in patients under hemodialysis.

Safety of biological therapies for psoriasis: effects on reproductive potential and outcomes in male and female patients

The effects of biological therapies for psoriasis on pregnancy outcomes and lactation, and male fertility and mutagenicity are common concerns in the clinical setting. There is relatively little evidence to guide the clinician and patient. Here, we review the safety profile of the commonly used biological therapies for psoriasis in individuals of reproductive potential. Safety data were derived from large-scale registries, adverse event reporting databases, clinical trials and case reports. We assessed the effect of each therapy on adverse pregnancy outcomes including congenital malformations, and lactation with maternal administration, and male fertility and potential mutagenicity with paternal administration. We provide applicable guidance to inform clinician and patient before and after conception.