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Objective: Primary non-response to infliximab in Crohn's disease is still incompletely understood. Our aim was to further characterize the role of inflammatory burden during infliximab induction therapy., Materials and Methods: We studied a well-characterized cohort of 201 anti-TNF naive Crohn's disease patients treated with infliximab 5mg/kg at week 0, 2, 6 and 14 who had serum samples drawn just before every infusion. All serum samples were analyzed for CRP, albumin, TNF, IFN-γ, IL-6, IL-8, IL-10, infliximab trough concentrations (in-house-developed ELISA) and antibodies to infliximab (HMSA, Prometheus Laboratories Inc., San Diego, CA). Primary non-response was defined as the absence of clinical improvement at week 14., Results: The incidence of primary non-response to infliximab was 8% (n = 16). IL-8 concentrations at baseline were higher (p = .01) and albumin at week 6 was lower in primary non-responders (p = .01) compared to responders. During induction, IFN-γ and IL-6 concentrations decreased significantly at week 2 and week 6 in responders compared to primary non-responders (p < .05). Serum TNF increased significantly after each infliximab infusion and this increase from week 0 to week 14 was more pronounced in responders (p = .03). Multiple logistic regression identified TNF/CRP ratio at baseline as predictive for primary non-response to infliximab at week 14 (OR 2.8 (95% CI 1.4-5.5; p = .003))., Conclusions: In this intensively sampled cohort of Crohn's disease patients, we demonstrate that inflammatory burden is more determining for primary non-response than drug exposure or immunogenicity. Our findings furthermore suggest that the contribution of TNF in inflammation might be higher in primary non-response, contradicting the non-TNF-driven concept.

Objectives: Ample evidence exists that Anti-tumor necrosis factor (TNF) concentrations during induction determine short and long-term outcome in inflammatory bowel disease (IBD). We investigated if a variable number of tandem repeats (VNTR) polymorphism in the neonatal Fc-receptor (FcRn), responsible for extending half-life of IgG, influences anti-TNF concentrations in patients with IBD., Methods: Retrospective single-center study, including a cohort of 395 infliximab (IFX) naive IBD patients treated with IFX 5 mg/kg on weeks 0, 2, and 6 and a second cohort of 139 adalimumab naive patients, treated with adalimumab 160-80-40 mg on weeks 0, 2, and 4. Area under the serum anti-TNF concentration-time curve (AUC), from week 2 and 6 for IFX and week 2 and 4 for adalimumab, was used to identify factors influencing these drug concentrations., Results: The VNTR2/VNTR3 genotype was associated with a 14% lower IFX AUC compared with patients homozygous for VNTR3/VNTR3 (P=0.03), although this effect became apparent only when immunogenicity (26% lower concentrations, P=9 × 10 -5 ) was not present. Prior anti-TNF use predicted a 27% lower IFX AUC (P=0.002). Similarly, VNTR2/VNTR3 patients had a 24% predicted lower adalimumab AUC than VNTR3/VNTR3 patients (P=0.005). The combined presence of VNTR2/VNTR3 genotype, male gender, and prior IFX use predicted a 41% lower adalimumab AUC concentration (P=0.04)., Conclusions: The VNTR2/3 genotype in the FcRn gene is associated with lower IFX but also lower adalimumab drug exposure during induction in patients with IBD. Previously identified pharmacokinetic modifying factors were confirmed. Identifying risk factors in patients is important as higher induction doses may be needed to ensure optimal disease outcome.

Background and Aims: We studied the long-term outcome of patients with ulcerative colitis [UC] and primary non response [PNR] to infliximab and searched for predictors of colectomy in these patients., Methods: This retrospective, multi-centre study included UC patients from three European referral centres, with PNR to infliximab defined as a lack of clinical improvement after the induction therapy, leading to drug discontinuation. Relapse, for patients who continued on biologicals after PNR to infliximab, was defined as drug discontinuation for PNR, loss of response, or serious adverse event. Serum infliximab concentrations at Weeks 2 and 6 were evaluated using an enzyme-linked immunosorbent assay [ELISA] developed in house., Results: The study population consisted of 99 anti-tumour necrosis factor [TNF]-naïve patients with UC and PNR to infliximab. At the end of follow-up (median: 3.2 [interquartile range 1-6.3] years), 55 [55.6%] of these patients underwent colectomy. Multiple Cox regression analysis identified acute severe UC (hazard ratio [HR]: 24; 95% confidence interval [CI]: 2.5-231; p = 0.006], baseline C-reactive protein [CRP] > 5mg/l [HR: 11; 95% CI: 2.1-58.8; p = 0.005], baseline albumin < 40g/l [HR: 9.5; 95% CI: 1.3-71.4; p = 0.026], and infliximab concentration at Week 2 < 16.5 μg/ml [HR: 5.6; 95% CI: 1.1-27.8; p = 0.034] as independent predictors of colectomy. Regarding patients who continued on biologicals after PNR to infliximab, there was a marginally higher cumulative probability for relapse in patients switching to another anti-TNF agent compared with those swapping to vedolizumab [p logrank = 0.08]., Conclusions: About half of UC patients with PNR to infliximab will undergo colectomy. Patients with severe inflammation and low serum infliximab concetrations during the induction phase are at greatest risk., (Copyright © 2016 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Prediction of primary non-response [PNR] to anti-tumour necrosis factors [TNFs] in inflammatory bowel disease [IBD] is direly needed to select the optimal therapeutic class for a given patient. We developed a matrix-based prediction tool to predict response to infliximab [IFX] in Crohn's disease [CD] patients., Methods: This retrospective single-centre study included 201 anti-TNF naïve CD patients who started with IFX induction therapy. PNR occurred in 16 [8%] patients. Clinical, biological [including serum TNF and the IBD serology 6 panel and genetic [the 163 validated IBD risk loci] markers were collected before start. Based on the best fitted regression model, probabilities of primary response to IFX were calculated and arranged in a prediction matrix tool., Results: Multiple logistic regression withheld three final independent predictors [p < 0.05] for PNR: age at first IFX, {odds ratio (OR) (95% confidence interval [CI] of 1.1 (1.0-1.1)}, body mass index [BMI] (0.86 [0.7-1.0]), and previous surgery (4.4 [1.2-16.5]). The accuracy of this prediction model did not improve when the genetic markers were added (area under the curve [AUC] from 0.80 [0.67-0.93] to 0.78 [0.65-0.91]). The predicted probabilities for PNR to IFX increased from 1% to 53% depending on the combination of final predictors., Conclusions: Readily available clinical factors [age at first IFX, BMI, and previous surgery] outperform serological and IBD risk loci in prediction of primary response to infliximab in this real-life cohort of CD patients. This matrix tool could be useful for guiding physicians and may avoid unnecessary or inappropriate exposure to IFX in IBD patients unlikely to benefit., (Copyright © 2015 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: The formation of anti-infliximab antibodies (ATI) is associated with loss of response and adverse events in patients with inflammatory bowel diseases, leading to the introduction of ATI monitoring for guiding treatment adjustments. However, a lack of standardization among current available assays exists, hampering comparison of results from different studies. This study aimed to improve the harmonization of clinically validated ATI enzyme-linked immunosorbent assays (ELISAs) by introducing a monoclonal anti-infliximab antibody (MA-IFX)., Methods: A panel of MA-IFX was evaluated as calibrator in the first generation ATI ELISA. After selection of 1 MA-IFX, assay conditions were optimized and biotin-streptavidin-enhanced detection of bound infliximab was introduced. The novel second generation ELISA was used for reanalysis of 127 serum samples from a cohort of 12 patients with inflammatory bowel disease, previously identified as ATI positive., Results: Of 55 MA-IFX, MA-IFX10F9 was selected as calibrator in the ATI ELISA. After optimization of the assay conditions, a 4-fold improvement in sensitivity was obtained. Reanalysis of 127 serum samples revealed that in 5 of 12 patients (46%), ATI were detected at least 1 time point earlier with the second generation ELISA compared with the first generation ELISA. In 1 patient, the second generation ELISA allowed to detect ATI before the reinitiation of IFX after a drug holiday., Conclusions: In addition to the improved sensitivity and specificity of the second generation ATI ELISA, MA-IFX10F9 can serve as a universal calibrator to achieve assay harmonization. Moreover, the superiority of the second generation assay in analyzing serum of restarters was demonstrated.

Introduction: The advent of tumor necrosis factor (TNF) antagonists represented a radical change in the management of inflammatory bowel disease (IBD). Both in short- and long-term, anti-TNF therapy has been shown to reduce symptoms, heal mucosal ulcers, reduce hospitalizations and surgeries and spare corticosteroids., Areas Covered: A literature search to August 2013 was performed to identify the most relevant reports on the use of TNF antagonists in IBD. First, the authors focused on the mechanism of action of TNF antagonists. Second, they evaluated different indications, contraindications, the optimal time to start and the role of combining TNF antagonists with immunomodulators. Third, they explored the importance of mucosal healing, followed by the controversial topic on when TNF antagonists should be stopped. This is followed by the subjects of treatment failure, immunogenicity and therapeutic drug monitoring. Last, they analyzed safety issues including exposure to TNF antagonists during pregnancy., Expert Opinion: TNF antagonists have become indispensable in the management of IBD. Efforts to focus on treatment of inflammatory signs only and on optimization of treatment with therapeutic drug monitoring are underway. The advent of several new compounds and "biosimilars" will further challenge the position of TNF antagonists in the treatment algorithm of IBD.