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Introduction: Exposure-outcome relationship data show that higher infliximab concentrations are associated with better outcomes in patients with Crohn's disease (CD). However, most of these data were derived from adult patients on maintenance therapy. We aimed to investigate the association of infliximab concentrations during and early after induction therapy of infliximab with short-term and long-term clinical outcomes in a pediatric CD population., Methods: We conducted a post hoc analysis of the REACH trial which included pediatric patients with moderate-to-severe CD treated with infliximab (n = 103). The investigated outcomes were early clinical remission (CR) defined as a pediatric CD activity index score of ≤ 10, assessed at week 10, and long-term clinical response (LTCR) defined as a decrease from baseline in the pediatric CD activity index score of at least 15 points, with a total score of ≤ 30 and no need for drug discontinuation, assessed at weeks 30 and 54., Results: Based on multivariable logistic regression analysis, higher week 10 infliximab concentrations were independently associated with CR at week 10 (odds ratio: 1.54; 95% confidence interval: 1.06-2.22; P = 0.022) and LTCR at week 30 (odds ratio: 1.62; 95% confidence interval: 1.12-2.36; P = 0.010). Receiver operating characteristic analysis identified week 10 infliximab concentration thresholds of ≥7.1 μg/mL and ≥6.5 μg/mL to be associated with CR at week 10 and LTCR at week 30, respectively., Discussion: Higher postinduction infliximab concentrations are associated with both short-term and long-term favorable clinical outcomes in pediatric patients with CD. Tailoring dosing during induction to achieve higher infliximab exposure may lead to better outcomes in pediatric patients with CD., (Copyright © 2022 by The American College of Gastroenterology.)

Background & Aims: End points to determine the efficacy and safety of medical therapies for Crohn's disease (CD) and ulcerative colitis (UC) are evolving. Given the heterogeneity in current outcome measures, harmonizing end points in a core outcome set for randomized controlled trials is a priority for drug development in inflammatory bowel disease., Methods: Candidate outcome domains and outcome measures were generated from systematic literature reviews and patient engagement surveys and interviews. An iterative Delphi process was conducted to establish consensus: panelists anonymously voted on items using a 9-point Likert scale, and feedback was incorporated between rounds to refine statements. Consensus meetings were held to ratify the outcome domains and core outcome measures. Stakeholders were recruited internationally, and included gastroenterologists, colorectal surgeons, methodologists, and clinical trialists., Results: A total of 235 patients and 53 experts participated. Patient-reported outcomes, quality of life, endoscopy, biomarkers, and safety were considered core domains; histopathology was an additional domain for UC. In CD, there was consensus to use the 2-item patient-reported outcome (ie, abdominal pain and stool frequency), Crohn's Disease Activity Index, Simple Endoscopic Score for Crohn's Disease, C-reactive protein, fecal calprotectin, and co-primary end points of symptomatic remission and endoscopic response. In UC, there was consensus to use the 9-point Mayo Clinic Score, fecal urgency, Robarts Histopathology Index or Geboes Score, fecal calprotectin, and a composite primary end point including both symptomatic and endoscopic remission. Safety outcomes should be reported using the Medical Dictionary for Regulatory Activities., Conclusions: This multidisciplinary collaboration involving patients and clinical experts has produced the first core outcome set that can be applied to randomized controlled trials of CD and UC., (Copyright © 2022 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: ERELATE was a phase 4, multinational, retrospective, observational study., Aim: To evaluate the relationship between intravenous vedolizumab exposure and treatment outcomes over 52 weeks in adults with ulcerative colitis (UC) or Crohn's disease (CD)., Methods: Real-world data from patients with UC or CD treated with intravenous vedolizumab in nine centres in six countries were collected retrospectively. Treatment outcomes were collected at Weeks 14, 26 and 52. An established population pharmacokinetic model (incorporating observed vedolizumab concentrations based on a Bayesian approach) was used to predict individual vedolizumab exposure. Vedolizumab exposure-response relationship was evaluated overall, by indication and based on baseline characteristics., Results: The study population (n = 695; UC, n = 304; CD, n = 391) had a median age of 39 years; 47.9% were male and 86.9% had prior tumour necrosis factor antagonist exposure. By Week 14, clinical, endoscopic, deep (clinical plus endoscopic) and biologic remission was achieved by 47.3%, 59.6%, 30.7% and 19.0% of patients respectively. Higher vedolizumab trough concentration early in treatment was consistently associated with clinical remission at later time points. Clinical remission at Week 14 and Week 52 was associated with Week 6 trough concentrations of ≥31.0 and ≥32.0 μg/ml respectively. Importantly, multivariable analysis identified baseline clearance as the only exposure measure predictive of clinical and deep remission at Week 52., Conclusions: In this real-world study, a positive exposure-response relationship was observed for vedolizumab. Vedolizumab concentration during induction may be an important predictor of short- and long-term outcomes, and similarly, vedolizumab baseline clearance may be an important predictor of remission., (© 2022 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

Immune cell trafficking is a critical element of the intestinal immune response, both in homeostasis and in pathological conditions associated with inflammatory bowel disease (IBD). This process involves adhesion molecules, chemoattractants and receptors expressed on immune cell surfaces, blood vessels and stromal intestinal tissue as well as signalling pathways, including those modulated by sphingosine 1-phosphate (S1P). The complex biological processes of leukocyte recruitment, activation, adhesion and migration have been targeted by various monoclonal antibodies (vedolizumab, etrolizumab, ontamalimab). Promising preclinical and clinical data with several oral S1P modulators suggest that inhibition of lymphocyte egress from the lymph nodes to the bloodstream might be a safe and efficacious alternative mechanism for reducing inflammation in immune-mediated disorders, including Crohn's disease and ulcerative colitis. Although various questions remain, including the potential positioning of S1P modulators in treatment algorithms and their long-term safety, this novel class of compounds holds great promise. This Review summarizes the critical mediators and mechanisms involved in immune cell trafficking in IBD and the available evidence for efficacy, safety and pharmacokinetics of S1P receptor modulators in IBD and other immune-mediated disorders. Further, it discusses potential future approaches to incorporate S1P modulators into the treatment of IBD., (© 2022. Springer Nature Limited.)

In patients with Crohn's disease and ulcerative colitis, poor correlation between symptoms and active luminal inflammation has been well established. As a result, the field has moved towards the use of endoscopic assessment to evaluate inflammatory activity. Numerous endoscopic indices have been used for this purpose although none are completely validated. The Simple Endoscopic Score for Crohn's Disease and the Crohn's Disease Endoscopic Index of Severity have been used most frequently; however in addition to incomplete validation, they have important limitations for clinical use, including complexity of scoring and poor reliability of items such as stenosis. The Rutgeerts' score for postoperative Crohn's disease was developed primarily as a prognostic rather than evaluative tool and also requires additional validation. In ulcerative colitis, the Mayo endoscopic subscore has been used as the regulatory standard, although the Ulcerative Colitis Endoscopic Index of Severity may provide a more granular assessment of individual components of disease activity. The use of combined outcomes with patient reported outcomes (PROs) and endoscopic indices has received favor by regulatory bodies but require further validation. This review describes the indications for endoscopic assessment in trials, the indices most frequently utilized for these purposes, and potential future approaches to assessment of disease activity., (Copyright © 2022 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Introduction: Preliminary data indicates that proactive therapeutic drug monitoring (TDM) is associated with better outcomes compared with empiric dose escalation and/or reactive TDM, and that pharmacokinetic (PK) modelling can improve the precision of individual dosing schedules in Crohn's disease (CD). However, there are no data regarding the utility of a proactive TDM combined PK-dashboard starting early during the induction phase, when disease activity and drug clearance are greatest. The aim of this randomised, controlled, multicentre, open-label trial is to evaluate the efficacy and safety of a proactive TDM combined PK dashboard-driven infliximab dosing compared with standard of care (SOC) dosing in patients with moderately to severely active CD., Methods and Analysis: Eligible adolescent and adult (aged ≥16-80 years) patients with moderately to severely active CD will be randomised 1:1 to receive either infliximab monotherapy with proactive TDM using a PK dashboard (iDose, Projections Research) or SOC infliximab therapy, with or without a concomitant immunomodulator (IMM) (thiopurine or methotrexate) at the discretion of the investigator. The primary outcome of the study is the proportion of subjects with sustained corticosteroid-free clinical remission and no need for rescue therapy from week 14 throughout week 52. Rescue therapy is defined as any IFX dose escalation other than what is forecasted by iDose either done empirically or based on reactive TDM; addition of an IMM after week 2; reintroduction of corticosteroids after initial tapering; switch to another biologic or need for CD-related surgery. The secondary outcomes will include both efficacy and safety end points, such as endoscopic and biological remission, durability of response and CD-related surgery and hospitalisation., Ethics and Dissemination: The protocol has been approved by the Institutional Review Board Committee of the Beth Israel Deaconess Medical Center (IRB#:2021P000391). Results will be disseminated in peer-reviewed journals and presented at scientific meetings., Trial Registration Number: NCT04835506., Competing Interests: Competing interests: ASC: reports consultancy fees from Janssen, AbbVie, Artugen, Procise, Prometheus, Arena, Grifols, Bacainn, Bristol Myers Squibb. VJ has received consulting/advisory board fees from AbbVie, Alimentiv (formerly Robarts Clinical Trials), Arena Pharmaceuticals, Asieris, Bristol Myers Squibb, Celltrion, Eli Lilly, Ferring, Fresenius Kabi, Galapagos, GlaxoSmithKline, Genetech, Gilead, Janssen, Merck, Mylan, Pandion, Pendopharm, Pfizer, Reistone Biopharma, Roche, Sandoz, Takeda, Teva, Topivert; speaker’s fees from, AbbVie, Ferring, Galapagos, Janssen Pfizer Shire, Takeda. CS: reports consultancy fees from AbbVie, BMS, Lilly, Janssen, Pfizer, Prometheus, Takeda, Trellus Health; speaker's fees for CME activities for AbbVie, Janssen, Pfizer, Takeda; grant support from the Crohn’s and Colitis Foundation, Leona M. and Harry B. Helmsley Charitable Trust, AbbVie, Janssen, Pfizer, Takeda; intellectual property owned by MiTest Health (Software Company) and ColonaryConcepts; equity interest and co-founder of MiTest Health and ColonaryConcepts. KP reports lecture fees from Mitsubishi Tanabe Pharma and Physicians Education Resource; consultancy fee from Prometheus Laboratories and scientific advisory board fees from ProciseDx and Scipher Medicine Corporation. JFV: reports research support from Roche/Genentech, Takeda, Applied Molecular Transport, Celgene/Bristol Myers Squibb, AbbVie, Arena Pharmaceuticals. GZ: reports consulting fees from Alimentiv. BC: reports financial support for advisory boards and consultancy from AbbVie, Celgene-Bristol Myers Squibb, Pfizer, Sublimity Therapeutics, Takeda, TARGET RWE; CME Companies: Cornerstones, Vindico; speaker's fees from AbbVie; educational grant from Pfizer. MD: reports consultancy fees from AbbVie, Arena Pharmaceuticals, Boehringer Ingelheim International, Bristol Myers Squibb, Cengene, Eli Lilly and Company, F. Hoffmann-La Roche, Genentech, Gilead, Janssen Global Services, Pfizer, Prometheus Biosciences, Takeda Pharmaceuticals USA, UCB SA; research grants from AbbVie, Janssen Global Services, Pfizer, Prometheus Biosciences; ownership interest (stocks) Trellus Health and holds licensing fee with Takeda Pharmaceuticals USA. TR: reports speaker's fees from Takeda Pharmaceuticals, Janssen, Pfizer, Bristol Myers Squibb; data adjudication committee fees from Ferring/Rebiotix; advisory boards fees from AbbVie, Arena, Boehringer Ingelheim, Bristol Myers Squibb/Celgene, Coral Genomics (and shareholder), Ferring, Genentech/Roche, Gilead, Gossamer, Intercept, Janssen, Lilly, Pfizer, Prometheus, Sanofi, Takeda. BES: discloses research grants from Takeda, Pfizer, Theravance Biopharma R&D, Janssen; consulting fees from 4D Pharma, Abivax, AbbVie, Alimentiv, Allergan, Amgen, Arena Pharmaceuticals, AstraZeneca, Bacainn Therapeutics, Boehringer-Ingelheim, Boston Pharmaceuticals, Bristol yers Squibb, Calibr, Capella Bioscience, Celgene, Celltrion Healthcare, ClostraBio, Enthera, F. Hoffmann-La Roche, Ferring, Galapagos, Gilead, GlaxoSmithKline, GossamerBio, Immunic, Index Pharmaceuticals, Innovation Pharmaceuticals, Ironwood Pharmaceuticals, Janssen, Kaleido, Kallyope, Lilly, MiroBio, Morphic Therapeutic, Oppilan Pharma, OSE Immunotherapeutics, Otsuka, Palatin Technologies, Pfizer, Progenity, Prometheus Biosciences, Prometheus Laboratories, Protagonist Therapeutics, Q32 Bio, Redhill Biopharma, Rheos Medicines, Salix Pharmaceuticals, Seres Therapeutics, Shire, Sienna Biopharmaceuticals, Sun Pharma, Surrozen, Takeda, Target PharmaSolutions, Teva Branded Pharmaceutical Products R&D, Thelium, Theravance Biopharma R&D, TLL Pharma, USWM Enterprises, Ventyx Biosciences, Viela Bio, Vivante Health, Vivelix Pharmaceuticals; and stock for Vivante Health and Ventyx Biosciences. NVC: received research grants from R-Biopharm, Takeda and UCB; and personal fees from AcelaBio, Alimentiv, Celltrion, ProciseDX, Prometheus, R-Biopharm, Takeda, UCB, Ventyx and Vividion. The remaining authors declare no conflict of interest., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Patients treated with immune checkpoint inhibitors (ICIs) may develop ICI-associated enterocolitis, for which there is no approved treatment., Aims: We aimed to systematically review the efficacy and safety of medical interventions for the prevention and treatment of ICI-associated enterocolitis., Methods: MEDLINE, EMBASE, and the Cochrane Library were searched to identify randomized controlled trials (RCTs), cohort and case-control studies, and case series/reports, evaluating interventions (including corticosteroids, biologics, aminosalicylates, immunosuppressants, and fecal transplantation) for ICI-associated enterocolitis. Clinical, endoscopic, and histologic efficacy endpoints were evaluated. The Grading of Recommendations, Assessment, Development, and Evaluation criteria were used to assess overall quality of evidence., Results: A total of 160 studies (n = 1514) were included (one RCT, 3 retrospective cohort studies, 156 case reports/case series). Very low quality evidence from one RCT suggests budesonide is not effective for prevention of ICI-associated enterocolitis in ipilimumab-treated patients (relative risk 0.93 [95% confidence interval 0.56, 1.56]). Very low quality evidence suggests that corticosteroids, infliximab, and vedolizumab may be effective for treatment of ICI-associated enterocolitis by inducing clinical response and remission. No validated indices for measuring disease activity were used. Biologic treatment was used in 42% (641/1528) of patients, as reported in 97 studies. ICIs were discontinued in 65% (457/702) of patients, as reported in 63 studies., Conclusions: Current treatment recommendations for ICI-associated enterocolitis are based on very low quality evidence, primarily from case reports and case series. Large-scale prospective cohort studies and RCTs are needed to develop prophylactic and therapeutic treatments to minimize interruption or discontinuation of oncological therapies., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Eosinophils have been implicated in the pathogenesis of ulcerative colitis and have been associated with disease course and therapeutic response. However, associations between eosinophil density, histologic activity, and clinical features have not been rigorously studied., Methods: A deep learning algorithm was trained to identify eosinophils in colonic biopsies and validated against pathologists' interpretations. The algorithm was applied to sigmoid colon biopsies from a cross-sectional cohort of 88 ulcerative colitis patients with histologically active disease as measured by the Geboes score and Robarts histopathology index (RHI). Associations between eosinophil density, histologic activity, and clinical features were determined., Results: The eosinophil deep learning algorithm demonstrated almost perfect agreement with manual eosinophil counts determined by 4 pathologists (interclass correlation coefficients: 0.805-0.917). Eosinophil density varied widely across patients (median 113.5 cells per mm2, interquartile range 108.9). There was no association between eosinophil density and RHI (P = 0.5). Significant differences in eosinophil density were seen between patients with Montreal E3 vs E2 disease (146.2 cells per mm2 vs 88.2 cells per mm2, P = 0.005). Patients on corticosteroids had significantly lower eosinophil density (62.9 cells per mm2 vs 124.1 cells per mm2, P = 0.006). No association between eosinophil density and biologic use was observed (P = 0.5)., Conclusions: We developed a deep learning algorithm to quantify eosinophils in colonic biopsies. Eosinophil density did not correlate with histologic activity but did correlate with disease extent and corticosteroid use. Future studies applying this algorithm in larger cohorts with longitudinal follow-up are needed to further elucidate the role of eosinophils in ulcerative colitis., (© 2021 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Artificial intelligence [AI] techniques are quickly spreading across medicine as an analytical method to tackle challenging clinical questions. What were previously thought of as highly complex data sources, such as images or free text, are now becoming manageable. Novel analytical methods merge the latest developments in information technology infrastructure with advances in computer science. Once primarily associated with Silicon Valley, AI techniques are now making their way into medicine, including in the field of inflammatory bowel diseases [IBD]. Understanding potential applications and limitations of these techniques can be difficult, in particular for busy clinicians. In this article, we explain the basic terminologies and provide a particular focus on the foundations behind state-of-the-art AI methodologies in both imaging and text. We explore the growing applications of AI in medicine, with a specific focus on IBD to inform the practising gastroenterologist and IBD specialist. Finally, we outline possible future uses of these technologies in daily clinical practice., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background and Aims: Quantifying placebo rates and the factors influencing them are essential to inform trial design. We provide a contemporary summary of clinical, endoscopic, histological and safety placebo rates in induction and maintenance clinical trials of ulcerative colitis, and identify factors influencing them., Methods: MEDLINE, EMBASE and the Cochrane library were searched from April 2014 to April 2020, updating a prior meta-analysis that searched from inception to April 2014. We included placebo-controlled trials of aminosalicylates, corticosteroids, immunosuppressives, small-molecules and biologics in adults with ulcerative colitis. Placebo rates were pooled using random-effects and mixed-effects meta-regression models to assess the associated study-level., Results: In 119 trials [92 induction, 27 maintenance] clinical, endoscopic and histological remission placebo rates for induction trials were 11% (95% confidence interval [CI] 9-13%), 19% [95% CI 15-23%] and 15% [95% CI 11-19%], respectively; for maintenance trials, clinical and endoscopic placebo remission rates were 18% [95% CI 12-25%] and 20% [95% CI 15-25%], respectively. Higher endoscopic subscore and a higher rate of exposure to prior biologic therapy at enrolment were associated with lower clinical and endoscopic placebo remission rates. Absence of central reading was associated with an increase in placebo endoscopic response and remission rates. More follow-up visits and increasing trial duration were associated with higher clinical placebo rates., Conclusions: Placebo rates in ulcerative colitis trials vary according to the endpoint assessed, whether it is for assessment of response or remission, and whether the trial is designed for induction or maintenance. These contemporary rates across different endpoints and drug classes will help to inform trial design., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Therapeutic drug monitoring (TDM) with measurement of serum drug and antidrug antibodies (ADAb) is used widely to confirm therapeutic exposure, rule out immunogenicity, and optimize treatment of biologics in patients with inflammatory bowel diseases. 1 A recent genome-wide association study found the variant HLA-DQA1∗05 to increase the risk of development of antibodies against infliximab (IFX) and adalimumab (ADM) 2-fold, regardless of concomitant immunomodulator use. 2 , 3 However, there is currently limited evidence showing whether patients who develop antibodies to 1 anti-tumor necrosis factor (TNF) are prone to develop antibodies to the subsequent anti-TNF. Our aim was to investigate the risk of subsequent antibody development in cases (with ADAb to prior anti-TNF) versus control subjects (without ADAb to prior anti-TNF) using a large cohort of patients with inflammatory bowel diseases who underwent TDM with a drug-tolerant assay., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Therapeutic drug monitoring (TDM) has emerged as a useful tool for optimising the use of biologics, and in particular anti-tumour necrosis factor (anti-TNF) therapy, in inflammatory bowel disease (IBD). However, challenges remain and are hindering the widespread implementation of TDM in clinical practice. These barriers include identification of the optimal drug concentration to target, the lag time between sampling and results, and the proper interpretation of anti-drug antibody titres among different assays. Solutions to overcome these barriers include the harmonisation of TDM assays and the use of point-of-care testing. Other unmet needs include well designed prospective studies and randomised controlled trials focusing on proactive TDM, particularly during induction therapy. Future studies should also investigate the utility of TDM for biologics other than anti-TNF therapies in both IBD and other immune-mediated inflammatory diseases such as rheumatoid arthritis and psoriasis, and the use of pharmacokinetic modelling dashboards and pharmacogenetics towards individual personalised medicine., Competing Interests: Declaration of interests KP has received a lecture fee from Mitsubishi Tanabe Pharma and Physicians Education Resource; a consultancy fee from Prometheus Laboratories; and scientific advisory board fees from ProciseDx and Scipher Medicine Corporation. NVC has received research grants and personal fees from R-Biopharm, Takeda, and UCB; and personal fees from Alimentiv (formerly Robarts Clinical Trials), Celltrion, and Prometheus Laboratories. ASC has received consultancy fees from AbbVie, Janssen, Takeda, Bacainn, Arena Pharmaceuticals, Grifols, Prometheus Laboratories, Samsung, Bristol Myers Squibb, and Pfizer; and research support from Inform Diagnostics. SV has received grants from AbbVie, Johnson and Johnson, Pfizer, and Takeda; consultancy fees from AbbVie, Arena Pharmaceuticals, Avaxia, Boehringer Ingelheim, Celgene, Dr Falk Pharma, Ferring, Galapagos, Genentech (Roche), Gilead, Hospira, Janssen, Mundipharma, Merck Sharp & Dohme, Pfizer, Prodigest, Progenity, Prometheus Biosciences, Alimentiv, Second Genome, Shire, Takeda, Theravance, and Tillots Pharma; and speaker fees from AbbVie, Dr Falk Pharma, Ferring, Galapagos, Genentech-Roche, Janssen, Pfizer, Shire, Takeda, and Tillots Pharma. NA has received a grant from Pfizer and lecture fees from Janssen, Pfizer, and Takeda. TK reports personal fees from Alfresa Pharma, Covidien, Eli Lilly, Ferring Pharmaceuticals, Janssen, Kyorin Pharmaceutical, Mochida Pharmaceutical, Nippon Kyaku, Pfizer, Takeda Pharmaceutical, Thermo Fisher Scientific, AbbVie, Astellas, Celltrion, EA Pharma, Nippon Kyaku, Mochida Pharmaceutical, Mitsubishi Tanabe Pharma, Zeria Pharmaceutical, Gilead Sciences, Janssen, and JIMRO; and grants from AbbVie, EA Pharma, Otsuka Holdings, Zeria Pharmaceutical, Kyorin Pharmaceutical, Mochida Pharmaceutical, Thermo Fisher Scientific, Alfresa Pharma, and Nippon Kyaku. WJS reports research grants from AbbVie, Abivax, Arena Pharmaceuticals, Boehringer Ingelheim, Celgene, Genentech, Gilead Sciences, GlaxoSmithKline, Janssen, Lilly, Pfizer, Prometheus Biosciences, Seres Therapeutics, Shire, Takeda, and Theravance Biopharma; consultancy fees from AbbVie, Abivax, Admirx, Alfasigma, Alimentiv, Alivio Therapeutics, Allakos, Amgen, Applied Molecular Transport, Arena Pharmaceuticals, Salix (Bausch Health), Beigene, Bellatrix Pharmaceuticals, Boehringer Ingelheim, Boston Pharmaceuticals, Bristol Myers Squibb, Celgene, Celltrion, Cellularity, Cosmo Pharmaceuticals, Escalier Biosciences, Equillium, Forbion, Genentech (Roche), Gilead Sciences, Glenmark Pharmaceuticals, Gossamer Bio, Immunic, Index Pharmaceuticals, Intact Therapeutics, Janssen, Kyverna Therapeutics, Landos Biopharma, Lilly, Oppilan Pharma, Otsuka, Pandion Therapeutics, Pfizer, Progenity, Prometheus Biosciences, Prometheus Laboratories, Protagonists Therapeutics, Provention Bio, Reistone Biopharma, Seres Therapeutics, Shanghai Pharma Biotherapeutics, Shire, Shoreline Biosciences, Sublimity Therapeutics, Surrozen, Takeda, Theravance Biopharma, Thetis Pharmaceuticals, Tillotts Pharma, UCB, Vendata Biosciences, Ventyx Biosciences, Vimalan Biosciences, Vivelix Pharmaceuticals, Vivreon Biosciences, and Zealand Pharma; and stock or stock options from Allakos, BeiGene, Gossamer Bio, Oppilan Pharma, Prometheus Biosciences, Prometheus Laboratories, Progenity, Shoreline Biosciences, Ventyx Biosciences, Vimalan Biosciences, and Vivreon Biosciences. PMI reports lecture fees from AbbVie, Bristol Myers Squibb, Celgene, Falk Pharma, Ferring, Gilead, Merck Sharp & Dohme, Janssen, Pfizer, Takeda, Tillotts, Sapphire Medical, Sandoz, Shire, and Warner Chilcott; financial support for research from Merck Sharp & Dohme, Pfizer, and Takeda; and advisory fees from AbbVie, Arena Pharmaceuticals, Genentech, Gilead, Hospira, Janssen, Lilly, Merck Sharp & Dohme, Pfizer, Pharmacosmos, Procise, Prometheus Biosciences, Roche, Sandoz, Samsung Bioepis, Takeda, Topivert, VHsquared, Vifor Pharma, and Warner Chilcott. MF reports financial support for research from AbbVie, Amgen, Biogen, Janssen, Pfizer, and Takeda; consultancy fees from AbbVie, Boehringer-Ingelheim, Celltrion, Janssen, Lilly, Medtronic, Merck Sharp & Dohme, Pfizer, Sandoz, Takeda, and Thermo Fisher Scientific; and speaker fees from AbbVie, Amgen, Biogen, Boehringer-Ingelheim, Falk, Ferring, Janssen, Lamepro, Merck Sharp & Dohme, Mylan, Pfizer, Sandoz, Takeda, and Truvion Healthcare. PGK has received consultancy and speaker fees from AbbVie, Janssen, Pfizer, Takeda, Ferring, and Novartis; and scientific grants from Takeda and Pfizer. DD has served as a speaker, a consultant, and an advisory board member for Merck Sharp & Dohme, AbbVie, Takeda, Pfizer, Janssen, Amgen, Biogen, and Krka. JL has received unrestricted grants from AbbVie, Almirall, Celgene, Eli Lilly, Janssen-Cilag, LEO Pharma, Novartis, and UCB; speaker fees for AbbVie, Almirall, BMS, Janssen-Cilag, Pfizer, and UCB; and consultancy fees for AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen-Cilag, LEO Pharma, Novartis, and UCB. NK has received speaker fees from Janssen. WA has received consultancy fees from AbbVie, Amgen, Arena Pharmaceuticals, Dynacare, Janssen, Merck, Novartis, Pfizer, Sandoz, and Takeda. AJY has received consultant or advisory board fees from Prometheus Laboratories, Takeda, Arena Pharmaceuticals, and Bristol Myers Squibb. SD has served as a speaker, consultant, and advisory board member for Schering-Plough, AbbVie, Merck Sharp & Dohme, UCB, Ferring, Cellerix, Takeda, Nycomed, Pharmacosmos, Actelion, Alphawasserman, Genentech, Grunenthal, Pfizer, AstraZeneca, Novo Nordisk, Cosmo Pharmaceuticals, Vifor Pharma, Johnson and Johnson, Nikkiso Europe, and Theravance. MCD has received consultancy fees from Janssen, AbbVie, Pfizer, Takeda, UCB, Celgene, Bristol Myers Squibb, Prometheus Biosciences, Arena Pharmaceuticals, and Lilly; and grant support from AbbVie, Pfizer, and Janssen. LPB has received grant support from AbbVie, Merck Sharp & Dohme, and Takeda; consulting fees from AbbVie, Janssen, Genentech, Ferring, Tillots, Pharmacosmos, Celltrion, Takeda, Boerhinger-Ingelheim, Pfizer, Index Pharmaceuticals, Sandoz, Celgene, Biogen, Samsung Bioepis, Alma, Sterna, Nestle, Enterome, Allergan, Merck Sharp & Dohme, Roche, Arena Pharmaceuticals, Gilead, Hikma, Amgen, Bristol Myers Squibb, Vifor, Norgine, Mylan, Lilly, Fresenius, Oppilan Pharma, Sublimity Therapeutics, Applied Molecular Transport, OSE Immunotherapeutics, and Enthera; and stock or stock options from Clinical Trials Mobile Application. All other authors declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Certolizumab pegol (CZP) is effective for moderately to severely active Crohn's disease (CD). Higher plasma concentrations are associated with better outcomes and increased drug clearance is the driver of subtherapeutic CZP concentrations., Objective: We aimed to develop a prediction model incorporating predicted CZP clearance and patient variables to allow estimation of the probability for remission prior to initiating therapy., Methods: A population pharmacokinetic model estimated baseline CZP clearance in patients with CD from nine phase II and III trials. Multivariable prediction models were developed and validated using the PRECiSE 1 and PRECiSE 2 datasets to identify candidate predictors for a composite remission outcome (Crohn's Disease Activity Index ≤ 150 and fecal calprotectin concentration ≤ 250 μg/g) at Weeks 6 or 26. An online clinical decision support tool (CDST) was developed., Results: Baseline predicted CZP clearance ≥ 0.5 L/day was associated with subtherapeutic Week 6 CZP plasma concentrations. Baseline weight (odds ratio [OR] 1.04; 95% confidence interval [CI] 1.02-1.07), calculated CZP clearance (OR 0.92; 95% CI 0.87-0.96), hematocrit (OR 2.55; 95% CI 1.43-4.54), and fecal calprotectin (OR 0.66; 95% CI 0.54-0.80) were associated with Week 6 remission (p ≤ 0.0015 for all predictors). Baseline weight (OR 1.04; 95% CI 1.02-1.07), calculated CZP clearance (OR 0.93; 95% CI 0.88-0.97), and Patient-Reported Outcome-2 (PRO2) (OR 0.93; 95% CI 0.87-0.99) were associated with Week 26 remission (p ≤ 0.033 for all predictors)., Conclusions: Patients who are predicted to have accelerated baseline CZP clearance are at risk of subtherapeutic CZP concentrations. Patient-level probabilities for a composite remission outcome can be predicted for patients with CD by entering commonly available patient- and disease-related factors into an online CDST ( https://premedibd.com ) incorporating predicted CZP clearance., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Although there is interest in developing pharmacotherapies for the treatment of immune checkpoint inhibitor-associated enterocolitis (ICIC), there is currently no consensus on how to optimally measure disease activity in this condition., Aims: To identify all scoring indices used for the measurement of disease activity in ICIC, assess their operating properties, and explore their potential utility as outcome measures., Methods: We searched MEDLINE, EMBASE and the Cochrane Library from inception to November 2020 to identify studies that evaluated disease activity and severity in patients with ICI-associated enterocolitis. These scoring tools could be designed specifically for ICIC or adapted from other diseases, and assessed clinical, endoscopic, or histologic disease activity., Results: Sixty-four studies were included. The Common Terminology Criteria for Adverse Events is commonly used to describe symptoms, although has only been partially validated and was not designed as a disease activity index. Endoscopic and histologic indices used in inflammatory bowel disease have been adopted for ICIC including the Mayo Endoscopic Subscore, Ulcerative Colitis Endoscopic Index of Severity, Simple Endoscopic Score for Crohn's Disease, Nancy Histological Index, Robarts Histopathological Index, and Geboes Score, among others. None of these indices has been validated for use in ICIC, and all lacked content validity and responsiveness., Conclusions: There are no validated clinical, endoscopic, or histologic outcomes to assess disease activity in ICIC. Development and validation of reliable and responsive outcome measures that can be used to measure disease activity will be paramount for both clinical practice and for the development of treatments., (© 2021 John Wiley & Sons Ltd.)

Background: The aim of this study was to assess the relationship between serum vedolizumab (VDZ) concentrations and antibodies to VDZ (ATV) in a large cohort of patients with inflammatory bowel diseases. Furthermore, we evaluated the association between serum VDZ concentrations and a novel serum-based biomarker panel designated as the endoscopic healing index (EHI), developed and validated for identifying mucosal inflammation in patients with Crohn's disease (CD)., Methods: Retrospective study where results from patient samples submitted to a commercial clinical laboratory were included. Serum VDZ and ATV levels were analyzed using a drug-tolerant assay. In CD patients for whom both VDZ and EHI were available, VDZ concentrations were correlated with EHI. serum VDZ threshold analysis was performed using ROC curves, and the serum VDZ concentrations that best differentiated EHI < 20 (previously associated with endoscopic remission) were chosen., Results: A total of 9356 patients were included in the VDZ/ATV analysis. Detectable ATV was observed in 2.9% patients with significantly lower serum VDZ concentrations when compared to those with undetectable ATV [3.9 µg/mL (0-9.0) vs. 11.3 µg/mL (5.9-20.6), p < 0.0001]. Of the patients with serum VDZ result, 287 patients had a concomitant EHI test. An inverse correlation was observed between VDZ concentration and EHI (rho = - 0.20, p < 0.001). A serum VDZ concentration ≥ 15.7 µg/ml was best correlated wi th an EHI < 20 [AUROC: 0.67 (95% CI 0.57-0.77)]., Conclusions: Incidence of ATVs was low, but significantly associated with lower VDZ levels. A serum VDZ concentration threshold of ≥ 15.7 µg/ml was associated with endoscopic remission as defined by an EHI < 20., (© 2020. The Author(s).)

Publicly available ulcerative colitis (UC) gene expression datasets from observational studies and clinical trials include inherently heterogeneous disease characteristics and methodology. We used meta-analysis to identify a robust UC gene signature from inflamed biopsies. Eight gene expression datasets derived from biopsy tissue samples from noninflammatory bowel disease (IBD) controls and areas of active inflammation from patients with UC were publicly available. Expression- and meta-data were downloaded with GEOquery. Differentially expressed genes (DEG) in individual datasets were defined as those with fold change > 1.5 and a Benjamini-Hochberg adjusted P value < .05. Meta-analysis of all DEG used a random effects model. Reactome pathway enrichment analysis was conducted. Meta-analysis identified 946 up- and 543 down-regulated genes in patients with UC compared to non-IBD controls (1.2 and 1.7 times fewer up- and down-regulated genes than the median of the individual datasets). Top-ranked up- and down-regulated DEG were LCN2 and AQP8. Multiple immune-related pathways (e.g., 'Chemokine receptors bind chemokine' and 'Interleukin-10 signaling') were significantly up-regulated in UC, while 'Biological oxidations' and 'Fatty acid metabolism' were downregulated. A web-based data-mining tool with the meta-analysis results was made available ( https://premedibd.com/genes.html ). A UC inflamed biopsy disease gene signature was derived. This signature may be an unbiased reference for comparison and improve the efficiency of UC biomarker studies by increasing confidence for identification of disease-related genes and pathways., (© 2021. The Author(s).)

Therapeutic drug monitoring (TDM) is the measurement of drug and antidrug antibody concentrations in individuals to guide treatment decisions. In patients with Crohn disease (CD), TDM, used either reactively or proactively, is emerging as a valuable tool for optimization of tumor necrosis factor (TNF) antagonist therapy. Reactive TDM is carried out in response to treatment failure, whereas proactive TDM involves the periodic monitoring of patients responding to TNF antagonist therapy to allow treatment optimization. In patients with CD, most of the available data for TDM relate to the first-to-market TNF antagonist infliximab and, to a lesser extent, to adalimumab and certolizumab pegol. Several gastroenterology associations, including the American Gastroenterology Association, have endorsed the use of reactive TDM in patients with active CD. However, fewer recommendations currently exist for the use of proactive TDM, although several new prospective randomized controlled trials evaluating proactive TDM strategies have been published. In this review, the current evidence for reactive and proactive TDM is discussed, and a proactive treatment algorithm for certolizumab pegol based on previously published threshold concentrations is proposed., (© 2020 Crohn’s & Colitis Foundation. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation.)

Introduction: Perianal fistulising Crohn's disease (pfCD) can be somewhat treatment refractory. Higher infliximab trough levels (TLIs) may improve fistula healing rates; however, it remains unclear whether escalating infliximab therapy to meet higher TLI targets using proactive, or routine, therapeutic drug monitoring (TDM) improves outcomes. This randomised controlled trial aimed to assess whether infliximab therapy targeting higher TLIs guided by proactive TDM improves outcomes compared with standard therapy., Methods and Analysis: Patients with active pfCD will be randomised 1:1 to either the proactive TDM arm or standard dosing arm and followed up for 54 weeks. Patients in the proactive TDM arm will have infliximab dosing optimised to target higher TLIs. The targets will be TLI ≥ 25 µg/mL at week 2, ≥ 20 µg/mL at week 6 and ≥ 10 µg/mL during maintenance therapy. The primary objective will be fistula healing at week 32. Secondary objectives will include fistula healing, fistula closure, radiological fistula healing, patient-reported outcomes and economic costs up to 54 weeks. Patients in the standard dosing arm will receive conventional infliximab dosing not guided by TLIs (5 mg/kg at weeks 0, 2 and 6, and 5 mg/kg 8 weekly thereafter). Patients aged 18-80 years with pfCD with single or multiple externally draining complex perianal fistulas who are relatively naïve to infliximab treatment will be included. Patients with diverting ileostomies or colostomies and pregnant or breast feeding will be excluded. Fifty-eight patients per arm will be required to detect a 25% difference in the primary outcome measure, with 138 patients needed to account for an estimated 6.1% primary non-response rate and 10% dropout rate., Ethics and Dissemination: Results will be presented in peer-reviewed journals and international conferences. Ethics approval has been granted by the South Western Sydney Local Health District Human Research Ethics Committee in Australia., Trial Registration Number: Australian New Zealand Clinical Trials Registry (ACTRN12621000023853); Pre-results., Competing Interests: Competing interests: NVC reports grants and personal fees from Takeda, grants and personal fees from UCB, grants from R-Biopharm, personal fees from Celltrion, personal fees from Prometheus, outside the submitted work. JA reports lecture fees, grants, Boards, Consultancies for Abbott, AbbVie, Allergan, Anatara, AstraZeneca, Bayer, Celegene, Ferring, Gilead, Hospira, Immuninc, ImmunsanT, Janssen, MSD, Nestle, Progenity, Pfizer, Shire, Takeda and Vifor, grants from the Royal Adelaide Hospital Research Fund, outside the submitted work. JB reports personal fees from Abbvie, personal fees from Pfizer, personal fees from BMS, grants and personal fees from Janssen, personal fees from Takeda, personal fees from Gilead, personal fees from Microba, grants and personal fees from Ferring, outside the submitted work. ALH has served as consultant, advisory board member or speaker for AbbVie, Arena, Atlantic, Bristol-Myers Squibb, Celgene, Celltrion, Falk, Ferring, Janssen, MSD, Napp Pharmaceuticals, Pfizer, Pharmacosmos, Shire and Takeda and serves on the Global Steering Committee for Genentech, outside the submitted work. DL reports consultancy fees from AbbVie, Astellas, AstraZeneca, Bristol-Myers Squibb, Novartis, Pfizer and Sanofi, grants from AbbVie, Astellas, AstraZeneca, Bristol-Myers Squibb, CSL-Behring, Novartis, Pfizer, Sanofi and Shire, and travel expenses from AstraZeneca and Bayer; outside the submitted work. GR-S reports fees to his institute from Ferring Australia, grants and fees to his institute from Janssen, fees to his institute from Takeda, fees to his institute from Pfizer, fees to his institute from AbbVie, outside the submitted work. JR reports grants from AbbVie, personal fees from Takeda, personal fees from Gilead, grants from Genentech, personal fees from Alimentiv, personal fees from Janssen, during the conduct of the study. TS reports personal fees from Seimens Workshop, personal fees from Bayer, outside the submitted work. CT reports grants from Janssen, grants from Pfizer, grants from MSD, outside the submitted work; and is a director of laboratory that performs therapeutic drug monitoring for infliximab. A-JW reports grants and personal fees from Ferring, personal fees and non-financial support from AbbVie, personal fees from Janssen, personal fees and non-financial support from Takeda, outside the submitted work. WN received grants from Janssen and Pfizer, during the conduct of the study; grants and personal and speaker fees from AbbVie, Takeda, Grants from Ferring and Shire unrelated to the submitted work. NSD reports personal fees from AbbVie, personal fees from Pfizer, personal fees from BMS, personal fees from Janssen, outside the submitted work. SC reports grants from Janssen, grants from Pfizer, during the conduct of the study; grants and personal fees from AbbVie, educational support from Aspen/Orphan Australia, grants and personal fees from Ferring, personal fees from Gilead, grants and personal fees from Janssen, personal fees from Novartis, grants, personal fees and educational support from Pfizer, grants, personal fees and educational support from Shire/Takeda, outside the submitted work., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Aims: Therapeutic drug monitoring (TDM) with measurement of serum drug and antidrug antibody concentrations is used to optimize tumor necrosis factor antagonists (anti-TNF). The endoscopic healing index (EHI) is a validated serum-based assay to measure mucosal inflammation in adults with Crohn disease (CD). Our objectives were to evaluate the relationship between EHI and TDM results and to determine the anti-TNF concentration range associated with EHI <20 (consistent with endoscopic remission)., Methods: Adult and pediatric patients with CD (N = 1731) were selected retrospectively from a clinical laboratory cohort. Patients were selected if they had an ICD-10 code for CD and if results for EHI and TDM were available within 30 days of each other. The relationship between EHI and TDM results was examined and the anti-TNF concentration range associated with EHI <20 vs >50 was evaluated., Results: Median anti-TNF concentration was higher in patients with EHI <20 vs >50 for infliximab (N = 796): 11.1 vs 3.4 µg/mL and for adalimumab (N = 935): 9.2 vs 5.0 µg/mL ( P < 0.0001 both drugs). Patients with antibodies to infliximab (12.8%) or adalimumab (14.9%) had lower anti-TNF concentrations ( P < 0.001 both drugs) and higher EHI ( P < 0.01 both drugs). The concentration range for infliximab: 5-15 µg/mL (5-9 µg/mL in pediatric patients) and for adalimumab: 5-10 µg/mL (8 µg/mL in pediatric patients) best discriminated EHI <20 vs >50., Conclusions: We report the anti-TNF concentration range associated with EHI <20. Combined testing of EHI and TDM is proposed as a noninvasive approach for treat-to-target management which could improve the ability to monitor disease and optimize anti-TNF therapy., (© The Author(s) 2021. Published by Oxford University Press on behalf of Crohn's & Colitis Foundation.)

Background & Aims: Histopathology is an emerging treatment target in ulcerative colitis (UC) clinical trials. Our aim was to provide guidance on standardizing biopsy collection protocols, identifying optimal evaluative indices, and defining thresholds for histologic response and remission after treatment., Methods: An international, interdisciplinary expert panel of 19 gastroenterologists and gastrointestinal pathologists was assembled. A modified RAND/University of California, Los Angeles appropriateness methodology was used to address relevant issues. A total of 138 statements were derived from a systematic review of the literature and expert opinion. Each statement was anonymously rated as appropriate, uncertain, or inappropriate using a 9-point scale. Survey results were reviewed and discussed before a second round of voting., Results: Histologic measurements collected using a uniform biopsy strategy are important for assessing disease activity and determining therapeutic efficacy in UC clinical trials. Multiple biopsy strategies were deemed acceptable, including segmental biopsies collected according to the endoscopic appearance. Biopsies should be scored for architectural change, lamina propria chronic inflammation, basal plasmacytosis, lamina propria and epithelial neutrophils, epithelial damage, and erosions/ulcerations. The Geboes score, Robarts Histopathology Index, and Nancy Index were considered appropriate for assessing histologic activity; use of the modified Riley score and Harpaz Index were uncertain. Histologic activity at baseline should be required for enrollment, recognizing this carries operational implications. Achievement of histologic improvement or remission was considered an appropriate and realistic therapeutic target. Current histologic indices require validation for pediatric populations., Conclusions: These recommendations provide a framework for standardized implementation of histopathology in UC trials. Additional work is required to address operational considerations and areas of uncertainty., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Infliximab is an effective treatment for moderate to severe ulcerative colitis (UC). Little is known about patient-related factors that might be used to predict endoscopic healing with infliximab therapy., Methods: We analyzed data from 484 patients included in the randomized trials of the effects of infliximab therapy for patients with UC (Active Ulcerative Colitis Trials [ACT]-1 and ACT-2). We used a 2-compartment population pharmacokinetic model to calculate baseline infliximab clearance. Two multivariable regression models were derived and validated for their ability to identify patients with endoscopic healing (Mayo endoscopic score, ≤1) at weeks 8 and 30, using only baseline variables. We developed a clinical decision support tool (CDST) and calculator to determine the probability of endoscopic healing in patients starting infliximab., Results: Higher baseline infliximab clearance, stool frequency, and rectal bleeding scores were associated negatively with endoscopic healing at week 8. In the validation set, a CDST score of 9 points or fewer identified patients without endoscopic healing at week 8 with 82% sensitivity (95% CI, 76%-88%), whereas a CDST score of 16 points or more identified patients with endoscopic healing at week 8 with 87% specificity (95% CI, 81%-94%). Higher baseline infliximab clearance, stool frequency score, white blood cell count, and lower body weight were associated negatively with endoscopic healing at week 30. In the validation set, CDST scores of 17 points or fewer identified patients without endoscopic healing at week 30 with 90% sensitivity (95% CI, 85%-95%), whereas scores greater than 22 points identified patients with endoscopic healing at week 30 with 80% specificity (95% CI, 73%-87%). External validation models had a modest predictive value, with an area under of the curve of 0.67 (95% CI, 0.61-0.74). Patient-level probabilities of endoscopic healing at weeks 8 or 30 can be calculated online (www.premedibd.com)., Conclusions: Using data from 2 clinical trials of patients receiving infliximab therapy for UC, we developed and validated the CDST, which uses data on infliximab clearance and baseline patient and disease measures to identify patients most likely to have endoscopic healing. This tool will facilitate therapy decision making and precision medicine., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Introduction: There are only limited data regarding the role of therapeutic drug monitoring in fistulizing Crohn's disease (CD). We investigated the association between both induction and maintenance serum infliximab concentrations and favorable therapeutic outcomes in patients with fistulizing CD., Methods: This was a post hoc analysis of the ACCENT-II trial evaluating patients with fistulizing CD receiving induction (n = 282) and maintenance infliximab therapy (n = 139). Investigated therapeutic outcomes at both week 14 and week 54 included fistula response, complete fistula response, C-reactive protein (CRP) normalization (≤5 mg/L) in patients with an elevated baseline CRP, and a more stringent outcome of composite remission, defined as combined complete fistula response and CRP normalization. Associations between serum infliximab concentrations and outcomes were assessed by multivariable logistic regression models., Results: Higher week 14 infliximab concentrations were independently associated with week 14 fistula response (odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.02-1.32; P = 0.019), and composite remission (OR: 2.32; 95% CI: 1.55-3.49; P < 0.001). Higher week 14 infliximab concentrations were also independently associated with week 54 composite remission (OR: 2.05; 95% CI: 1.10-3.82; P = 0.023). Based on receiver operating characteristic curve analysis, week 14 infliximab concentrations thresholds with combined maximal sensitivity and specificity of ≥20.2 μg/mL at week 2, ≥15 μg/mL at week 6, and ≥7.2 μg/mL at week 14 were associated with week 14 composite remission., Discussion: Higher post-induction infliximab concentrations are associated with early and long-term favorable therapeutic outcomes in patients with fistulizing CD., (Copyright © 2021 by The American College of Gastroenterology.)

Comparison data regarding anti-tumor necrosis factor drug concentrations in inflammatory bowel disease (IBD) between the enzyme-linked immunosorbent assay (ELISA) and the homogenous mobility shift assay (HMSA) are scarce. 1-3 As decisions in clinical practice depend on the thresholds that define a therapeutic drug concentration, it is important to determine if this varies based on the type of assay used for therapeutic drug monitoring. 4 We recently showed a discrepancy between a commercially available ELISA and the HMSA for both infliximab and adalimumab concentrations in patients with IBD. 5 Based on the results of the study, Prometheus Laboratories (San Diego, CA) initiated a comprehensive review of their HMSA assays and found that there was an upward drift for both infliximab (from December 2017 to May 2019) and adalimumab (from August 2017 to May 2019), including when our study was performed. Prometheus Laboratories corrected the errant values and reported the revised drug concentrations to physicians (Supplementary Methods). We aimed to compare the corrected infliximab and adalimumab concentrations with the original ELISA values., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Hospitalized patients with acute severe ulcerative colitis (ASUC) often require surgery. Although the tumor necrosis factor antagonist infliximab is an effective salvage therapy to prevent colectomy in patients with ASUC, optimal dosing is unclear. Calculated infliximab clearance has been associated with important outcomes in patients with ulcerative colitis, but its utility in patients with ASUC has not been established. We assessed the relationship between calculated the baseline infliximab clearance before infliximab salvage therapy and the requirement for colectomy in patients hospitalized for ASUC., Methods: We obtained data from hospitalized patients with ASUC who initiated infliximab therapy. We then calculated the baseline infliximab drug clearance in these patients based on an existing formula. The primary aim was to compare clearance between patients who required colectomy 6 months later and patients who did not require colectomy. Receiver operating characteristic curve analyses evaluated clearance thresholds for colectomy. Multivariable logistic regression analysis evaluated factors associated with colectomy., Results: In 39 patients with ASUC, the median baseline calculated clearance was higher in patients requiring colectomy at 6 months than in patients without colectomy (0.733 vs 0.569 L/d; P = .005). An infliximab clearance threshold of 0.627 L/d identified patients who required colectomy with 80.0% sensitivity and 82.8% specificity (area under the curve, 0.80). A higher proportion of patients with infliximab clearance of 0.627 L/d or more underwent colectomy within 6 months (61.5%) than patients with lower infliximab clearance values (7.7%) (P = .001). Multivariable analysis identified baseline infliximab clearance as the only factor associated with colectomy. The infliximab dose in the hospital was higher in patients who required colectomy. Results were similar at 30 days and 1 year., Conclusions: In patients hospitalized with ASUC, higher values of calculated infliximab clearance before infliximab administration is associated with higher rates of colectomy. Although patients who required colectomies received higher doses, data on infliximab concentrations are lacking. Infliximab pharmacokinetic models are needed for patients with ASUC to allow comparative trials on clearance-based vs standard dosing., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Aims: Mesalamine is the first-line therapy for treating mild-to-moderate ulcerative colitis. Multiple mesalamine formulations are available, with similar safety and efficacy profiles. Mesalamine is commonly administered as divided dosing, although once-daily dosing may provide benefits for patients. We evaluated the pharmacokinetics of three dosing regimens of two oral delayed-release mesalamine formulations in healthy adult volunteers., Methods: A randomised, open-label, parallel-group study of mesalamine pharmacokinetics following Lialda 2 × 1.2 g once daily (QD) (dose A), Asacol 6 × 400 mg QD (dose B), or Asacol 2 × 400 mg three times daily (TID) (dose C) over 7 days. Assessments included 5-aminosalicylic acid (5-ASA) and N-acetyl 5-aminosalicylic acid (N-Ac-5-ASA, primary metabolite) pharmacokinetics (A e (%), AUC 0-24 and C max ), safety and tolerability., Results: All enrolled volunteers (n = 37) completed the study. Steady state was achieved for all treatments by day 4. Ratios (95% CI) of means for steady-state AUC 0-24 (dose A vs B 90.3% [39.8, 204.8], dose A vs C 123.5% [55.3, 275.7], dose B vs C 136.8% [61.3, 305.5]) and C max (dose A vs B 106.0% [46.4, 242.2], dose A vs C 133.0% [59.1, 299.0], dose B vs C 125.5% [55.8, 282.1]) were similar for all 5-ASA treatments. Mean urinary excretion of 5-ASA plus N-Ac-5-ASA was comparable between treatments (dose A 21.3%, dose B 20.2%, dose C 17.9%). All treatment regimens were well tolerated; no safety issues were observed., Conclusions: Plasma and urine pharmacokinetics for Asacol TID, Asacol QD, and Lialda QD are similar, suggesting similar daily systemic exposures can be obtained with either TID or QD dosing. NCT00751699., (© 2020 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Our expanding knowledge of the pathophysiology of inflammatory bowel disease (IBD) has led to the development of a multitude of new therapies, including parenterally administrated biologic agents and new oral small molecules. Tofacitinib is the first compound of a promising class of new small molecules approved for the treatment of IBD. This pan-Janus kinase (JAK) inhibitor (JAKi) targets the four isoforms of cytokine associated JAKs (JAK1, JAK2, JAK3 and TYK2). Next generations JAKi with marked selectivity for specific JAK isoforms or gut-restricted effect are in development, with promising results in phase I and II clinical trials. Whether increased JAK selectivity will translate into more favorable clinical efficacy and safety profiles remains to be demonstrated in larger clinical trials. Here we provide an overview of the clinical and pharmacological aspects of these drugs and discuss how they may be incorporated in the current treatment paradigm for Crohn's disease and ulcerative colitis., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background & Aims: We created and validated a clinical decision support tool (CDST) to predict outcomes of vedolizumab therapy for ulcerative colitis (UC)., Methods: We performed logistic regression analyses of data from the GEMINI 1 trial, from 620 patients with UC who received vedolizumab induction and maintenance therapy (derivation cohort), to identify factors associated with corticosteroid-free remission (full Mayo score of 2 or less, no subscore above 1). We used these factors to develop a model to predict outcomes of treatment, which we called the vedolizumab CDST. We evaluated the correlation between exposure and efficacy. We validated the CDST in using data from 199 patients treated with vedolizumab in routine practice in the United States from May 2014 through December 2017., Results: Absence of exposure to a tumor necrosis factor (TNF) antagonist (+3 points), disease duration of 2 y or more (+3 points), baseline endoscopic activity (moderate vs severe) (+2 points), and baseline albumin concentration (+0.65 points per 1 g/L) were independently associated with corticosteroid-free remission during vedolizumab therapy. Patients in the derivation and validation cohorts were assigned to groups of low (CDST score, 26 points or less), intermediate (CDST score, 27-32 points), or high (CDST score, 33 points or more) probability of vedolizumab response. We observed a statistically significant linear relationship between probability group and efficacy (area under the receiver operating characteristic curve, 0.65), as well as drug exposure (P < .001) in the derivation cohort. In the validation cohort, a cutoff value of 26 points identified patients who did not respond to vedolizumab with high sensitivity (93%); only the low and intermediate probability groups benefited from reducing intervals of vedolizumab administration due to lack of response (P = .02). The vedolizumab CDST did not identify patients with corticosteroid-free remission during TNF antagonist therapy., Conclusions: We used data from a trial of patients with UC to develop a scoring system, called the CDST, which identified patients most likely to enter corticosteroid-free remission during vedolizumab therapy, but not anti-TNF therapy. We validated the vedolizumab CDST in a separate cohort of patients in clinical practice. The CDST identified patients most likely to benefited from reducing intervals of vedolizumab administration due to lack of initial response. ClinicalTrials.gov no: NCT00783718., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Vedolizumab, an α4β7 integrin antagonist, is an effective therapy for Crohn's disease (CD). Biomarkers are needed to guide therapy and predict outcomes. This study evaluated biomarker concentrations and outcomes in patients with CD undergoing vedolizumab treatment., Methods: Sera at weeks 0, 2, 6, 14, and ⩾26 were collected from vedolizumab-treated, refractory CD patients. Concentrations of soluble (s)-Vascular Cell Adhesion Molecule (VCAM)-1, s-Intercellular Cell Adhesion Molecule (ICAM)-1, s-Mucosal Addressin Cell Adhesion Molecule (MAdCAM)-1, and s-α4β7 integrin were evaluated for associations with achieving endoscopic remission., Results: A total of 22 patients with CD were included. In all patients, s-MAdCAM-1 decreased significantly and s-α4β7 increased compared with baseline. s-VCAM-1 and s-ICAM-1 changed differentially in patients who achieved remission. At week 6, median s-VCAM-1 (859.6 ng/ml versus 460.3 ng/ml, p  = 0.03) and s-ICAM-1 (545.7 ng/ml versus 286.2 ng/ml, p  = 0.03) concentrations were higher in patients who achieved endoscopic remission compared with those who did not, and similar differences were observed for s-ICAM-1 concentrations in patients who achieved clinical remission, compared with those who did not (669.1 ng/ml versus 291.0 ng/ml, p  = 0.04). Week 14 s-α4β7 concentrations were lower in patients who achieved endoscopic remission, compared with those who did not (7.5 ng/ml versus 17.6 ng/ml, p  = 0.020)., Conclusion: In all vedolizumab-treated CD patients, s-MAdCAM-1 decreased significantly and s-α4β7 increased. However, higher concentrations of s-ICAM-1 and s-VCAM-1 at week 6 and lower concentrations of s-α4β7 at week 14 differentiated patients who achieved endoscopic remission. These findings may help identify early predictors of response to vedolizumab treatment in patients with CD. Further validation in less refractory CD patients is needed., Competing Interests: Conflict of interest statement: AKH reports no conflicting interests. RB reports no conflicting interests. PSD reports research support and/or consulting from Takeda, Abbvie, Pfizer, Janssen, Buhlmann, Polymedco, Prometheus Biosciences. NVC reports research grants from R-Biopharm, grants and personal fees from Takeda and UCB, personal fees from Celltrion and Prometheus Biosciences. NN reports no conflicting interests. AJ is an employee of and reports stock options from Prometheus Biosciences. AM reports no conflicting interests. JN reports no conflicting interests. HL reports no conflicting interests. SS has received research grants from AbbVie and Janssen. JRN reports no conflicting interests. WJS reports research grants from Atlantic Healthcare Limited, Amgen, Genentech, Gilead Sciences, Abbvie, Janssen, Takeda, Lilly, Celgene/Receptos,Pfizer, Prometheus Laboratories (now Prometheus Biosciences); consulting fees from Abbvie, Allergan, Amgen, Arena Pharmaceuticals, Avexegen Therapeutics, BeiGene, Boehringer Ingelheim, Celgene, Celltrion, Conatus, Cosmo, Escalier Biosciences, Ferring, Forbion, Genentech, Gilead Sciences, Gossamer Bio, Incyte, Janssen, Kyowa Kirin Pharmaceutical Research, Landos Biopharma, Lilly, Oppilan Pharma, Otsuka, Pfizer, Progenity, Prometheus Biosciences (merger of Precision IBD and Prometheus Laboratories), Reistone, Ritter Pharmaceuticals, Robarts Clinical Trials (owned by Health Academic Research Trust, HART), Series Therapeutics, Shire, Sienna Biopharmaceuticals, Sigmoid Biotechnologies, Sterna Biologicals, Sublimity Therapeutics, Takeda, Theravance Biopharma, Tigenix, Tillotts Pharma, UCB Pharma, Ventyx Biosciences, Vimalan Biosciences, Vivelix Pharmaceuticals; and stock or stock options from BeiGene, Escalier Biosciences, Gossamer Bio, Oppilan Pharma, Prometheus Biosciences (merger of Precision IBD and Prometheus Laboratories), Progenity, Ritter Pharmaceuticals, Ventyx Biosciences, Vimalan Biosciences. Spouse: Opthotech - consultant, stock options; Progenity - consultant, stock; Oppilan Pharma - employee, stock options; Escalier Biosciences - employee, stock options; Prometheus Biosciences (merger of Precision IBD and Prometheus Laboratories) - employee, stock options; Ventyx Biosciences – employee, stock options; Vimalan Biosciences - employee, stock options. BSB reports research grant from Prometheus Biosciences and consulting fees from Pfizer., (© The Author(s), 2020.)

Background: The optimal ulcerative colitis biopsy protocol is unclear., Aim: To evaluate the number of biopsies required to accurately assess microscopic disease activity in ulcerative colitis METHODS: Biopsies from patients with ≥4 rectosigmoid samples, and clinical and endoscopic data, were retrospectively obtained from a prospective biobank. Histology and endoscopic videos were read blindly. A 4-biopsy Robarts Histopathology Index (RHI) reference score, consisting of the worst item-level ratings from four biopsies, was compared to 1-, 2- and 3-biopsy estimates. Agreement was determined using bivariate errors-in-variable regression analysis (acceptance interval: ±8.25). Endoscopic activity and disease location subgroup analyses were also performed., Results: Forty-six patients had ≥4 rectosigmoid biopsies available (N = 287). The 2-biopsy (tolerance interval: -7.66, 4.79) and 3-biopsy (tolerance interval: -4.86, 3.46) RHI scores demonstrated acceptable agreement with 4-biopsy scores. One-biopsy scores demonstrated unacceptable agreement (tolerance interval: -13.99, 7.78). Mean RHI scores using the 2-, 3- and 4-biopsy approaches were similar (6.1 ± 9.6 P = 0.36; 6.8 ± 10.5, P = 0.7; 7.5 ± 11.2), whereas the 1-biopsy estimate was lower (4.4 ± 8.1, P = 0.06). Histological remission rates were identical for the 2-, 3- and 4-biopsy methods (65.2%, P = 1.0). Subgroup analysis demonstrated that three biopsies were required in patients with endoscopically active disease. Sampling additional colonic locations yielded lower histological remission rates compared to rectosigmoid sampling alone (33.3% vs 61.9%, P = 0.1)., Conclusions: A minimum of two - conservatively, three - biopsies are required to reliably assess disease activity in a single colonic segment using the RHI. Further studies are needed of endoscopically active patients and sampling locations. These results have implications for biopsy strategies in clinical trials and practice., (© 2020 John Wiley & Sons Ltd.)

Inflammatory bowel disease, including ulcerative colitis and Crohn's disease, are chronic inflammatory disorders of the gastrointestinal tract which are characterised, in part, by an imbalance in the production of several pro- and anti-inflammatory cytokines. Although various agents are effective for inducing and maintaining remission, approximately 20% of patients are treatment-refractory and require surgery. Parenterally administered monoclonal antibody-based biologics are associated with adverse effects resulting in treatment discontinuation and/or immunogenicity, leading to loss of response to therapy. Approximately 50% of patients who initially respond to treatment with tumour necrosis factor antagonists lose response to therapy within the 1st year of treatment. Incidence of immunogenicity tends to decrease over time, but once present can persist for years, even after treatment discontinuation. Nonimmunogenic oral small molecule therapies, including Janus kinase inhibitors, are currently being developed and have demonstrated efficacy in early phase clinical trials, which has already led to regulatory approval of tofacitinib for the treatment of patients with moderate-to-severe ulcerative colitis. Differentiation of T cells into T helper cells, which are mediators of the inflammatory response in inflammatory bowel disease, is mediated by the Janus kinase signal transducer and activator of the transcription signalling pathway. Absorption and distribution of Janus kinase inhibitors occurs at the site of action in the gastrointestinal tract, and newer compounds are being developed with limited systemic absorption, potentially reducing the risk of adverse effects. The current review describes the clinical pharmacology of approved Janus kinase inhibitors, as well as those in clinical development for the treatment of inflammatory bowel disease., (© European Crohn’s and Colitis Organisation (ECCO) 2020.)

Anti-tumor necrosis factor (anti-TNF) drugs are often prescribed for the treatment of rheumatoid arthritis (RA) and other immune-mediated inflammatory diseases. Although this treatment has been shown to be effective in many patients, up to 40% of patients do not achieve disease control. Drug concentration in plasma may be a factor affecting the observed variability in therapeutic response. In this study, we aimed to identify the plasma concentrations of the anti-TNF certolizumab pegol (CZP), associated with improvement in disease activity in patients with RA. Data were pooled from three randomized, controlled clinical trials with a combined total of 1,935 patients analyzed. Clinical outcomes of low disease activity (LDA) and remission were defined as Disease Activity Score in 28 joints with C-reactive protein (DAS28(CRP)) ≤ 2.7 and < 2.3, respectively. Quartile analysis results indicated that there may be an exposure-response relationship between CZP concentration and LDA/remission outcomes at weeks 12 and 24; the association was strongest for LDA (P < 0.05). Receiver operating characteristic (ROC) analysis showed that CZP concentrations ≥ 28.0 μg/ml at week 12, and ≥ 17.6 μg/ml at week 24, were associated with a greater likelihood of achieving LDA/remission outcomes. Although confirmatory studies are warranted to define the optimal CZP therapeutic range at weeks 12 and 24, these data indicate that CZP concentrations may be associated with improvement of disease activity., (© 2020 The Authors. Clinical and Translational Science published by Wiley Periodicals, Inc. on behalf of the American Society for Clinical Pharmacology and Therapeutics.)

Cytokines are involved in intestinal homeostasis and pathological processes associated with inflammatory bowel disease (IBD). The biological effects of cytokines, including several involved in the pathology of Crohn's disease and ulcerative colitis, occur as a result of receptor-mediated signalling through the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) DNA-binding families of proteins. Although therapies targeting cytokines have revolutionized IBD therapy, they have historically targeted individual cytokines, and an unmet medical need exists for patients who do not respond to or lose response to these treatments. Several small-molecule inhibitors of JAKs that have the potential to affect multiple pro-inflammatory cytokine-dependent pathways are in clinical development for the treatment of IBD, with one agent, tofacitinib, already approved for ulcerative colitis and several other agents with demonstrated efficacy in early phase trials. This Review describes the current understanding of JAK-STAT signalling in intestinal homeostasis and disease and the rationale for targeting this pathway as a treatment for IBD. The available evidence for the efficacy, safety and pharmacokinetics of JAK inhibitors in IBD as well as the potential approaches to optimize treatment with these agents, such as localized delivery or combination therapy, are also discussed.

Introduction: We applied the Grading of Recommendations, Assessment, Development, and Evaluation framework to evaluate the performance of fecal calprotectin (FC) as an alternative to endoscopy in patients with moderate-to-severe ulcerative colitis (UC) treated with a biologic agent or tofacitinib., Methods: Individual participant data from the trials of infliximab, golimumab, vedolizumab, and tofacitinib for UC were pooled to generate prevalence of endoscopic activity (Mayo endoscopy score) across different combinations of the rectal bleeding score (RBS) and stool frequency score (SFS). These estimates were then combined with the data from an updated systematic review of the operating properties of FC to generate clinical scenario-specific assessments of the performance of FC as a predictor of endoscopic disease activity. A prespecified threshold of acceptability for false-negative (FN) and false-positive (FP) test results was set at 5%., Results: For patients with UC achieving RBS 0 + SFS 0/1, FC ≤ 50 μg/g may avoid endoscopy in 50% patients with a FN rate <5%. Similarly, for patients with RBS 2/3 + SFS 2/3, FC ≥ 250 μg/g potentially avoids endoscopy in approximately 50% patients with an FP rate <5%. The greatest uncertainty in the diagnostic performance for FC was observed in patients with UC achieving RBS 0 but having SFS 2/3, where FN and FP rates were consistently >10%, and endoscopic evaluation may be warranted., Discussion: Two clinical scenarios were identified where FC can be used with confidence for monitoring treatment response to biologics or tofacitinib in patients with UC without the requirement for endoscopy.

Background: Biologic therapies in patients with Crohn's disease often yield low clinical and endoscopic remission rates. After multiple failed therapies, combining two biologic therapies is possibly the sole medical alternative to recurrent surgery. However, data on this approach are limited., Aims: To assess the efficacy and safety of concomitant use of two biologic therapies in the largest cohort to date of refractory Crohn's disease patients., Methods: Data were extracted from Crohn's disease patients started on dual biologic therapy at two referral centres. Biologics utilised include infliximab, adalimumab, vedolizumab, ustekinumab, certolizumab and golimumab. The primary outcome was endoscopic improvement (>50% reduction in Simplified Endoscopic Score-Crohn's disease [SES-CD] or explicitly stated). Endoscopic remission (SES-CD < 3 or stated), clinical response (Crohn's disease-patient-reported outcome-2 score [PRO2] reduced by 8), clinical remission (PRO2 < 8), and C-reactive protein (CRP) were also assessed., Results: A total of 22 patients with 24 therapeutic trials of dual biologic therapy were identified. The majority of patients had prior surgical resections (91%), stricturing (59%) or penetrating (36%) phenotype, and perianal fistulas (50%). Median number of prior failed biologics was 4. Endoscopic improvement occurred in 43% of trials and 26% achieved endoscopic remission. Fifty per cent had clinical response and 41% achieved clinical remission. There were significant post-treatment reductions in median SES-CD (14.0 [12.0-17.5] to 6.0 [2.5-8.0], P = 0.0005], PRO-2 (24.1 [20.3-27.0] to 13.4 [4.6-21.8], P = 0.002] and CRP (17.0 [11.0-24.0] to 9.0 [4.0-14.0], P = 0.02). Presence of perianal fistulas decreased from 50% to 33%. Adverse events occurred in 13% of trials., Conclusion: Dual biologic therapy was associated with clinical, biomarker and endoscopic improvements in selected patients with refractory Crohn's disease who failed multiple biologics. Further studies are needed to validate this approach., (© 2020 John Wiley & Sons Ltd.)

Background: Data on the association of ustekinumab (UST) drug concentrations and clinical outcomes are conflicting. We assessed serum UST drug and anti-UST antibody concentrations using three commercially available assays., Methods: Sixty-one blood samples were analyzed for serum UST drug and anti-UST antibody concentrations using three assays: one homogeneous mobility shift assay (HMSA, Prometheus, Assay A), and two enzyme-linked immunosorbent assays (ELISA; Progenika, Dynacare, Assay B and Theradiag, Assay C)., Results: The median (IQR) serum UST concentrations for the three assays were: Assay A 7.50 (5.35 to 12.88) µg/mL, Assay B 4.02 (2.46 to 6.95) µg/mL and Assay C 4.35 (2.62 to 7.50) µg/mL. A Kruskal-Wallis test confirmed a statistically significant difference between the different assays, X 2 (2) = 30.606, p < 0.001. Linear regression showed near twofold increased difference in the absolute drug concentrations between the HMSA and either ELISA. Linear quantitative correlation was observed for all three assays ( r = 0.836 for A versus B, r = 0.792 for A versus C, r = 0.936 for B versus C; p < 0.01). The intraclass correlation coefficient (ICC) between assay A and B was 0.649 (95% confidence interval [CI] -0.208 to 0.874); assay A and C was 0.671 (95% CI -0.165 to 0.878); and assay B and C was 0.958 (95% CI 0.928 to 0.975); p < 0.001. No anti-UST antibodies were detected., Conclusion: A good correlation was observed for serum UST drug concentrations and a good agreement was observed between the ELISA tests. However, agreement was poor between the HMSA and each ELISA tests. Clinical recommendations regarding drug concentrations should be based on assay type used., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Canadian Association of Gastroenterology.)

Background: Treatment targets for ulcerative colitis are evolving towards achievement of endoscopic improvement and remission in addition to symptom resolution. It remains to be accurately quantified what proportion of patients with symptom resolution have residual endoscopic activity that might warrant treatment modification., Aim: To quantify the prevalence of endoscopic improvement and remission amongst ulcerative colitis patients with various permutations of patient-reported outcomes., Methods: Individual participant data from active intervention and placebo arms of clinical trials of infliximab, golimumab, vedolizumab and tofacitinib were pooled to estimate the prevalence of endoscopic improvement (Mayo endoscopic sub-score [MES] 0 or 1) and remission (MES 0) scores with various permutations of the rectal bleeding sub-score (RBS) and stool frequency sub-score (SFS) of the Mayo score, following induction (6-8 weeks) and maintenance (30-54 weeks) therapy. Subgroup analyses were performed by year of publication and centrally read endoscopy scoring., Results: Data from 2586 trial participants were analysed. Using locally scored endoscopy, the prevalence of endoscopic improvement and remission was highest among participants with a RBS 0 + SFS 0 post-induction (MES 0/1:81%, [95% CI 78-84]; MES 0:29% [26-33]) and during maintenance (MES 0/1:91% [87-93]; MES 0:57% [52-62]). Prevalence estimates were lower for more recently performed trials (P < .01). In comparison to locally scored endoscopy, when using central endoscopy scoring, the prevalence of endoscopic improvement and remission was lower post-induction (MES 0/1 57% [50-64], P < .001; MES 0 15% [11-21], P = .09) and during maintenance (MES 0/1 74% [67-81], P = .001; MES 0 31% [24-38], P = .001) for participants achieving a RBS 0 + SFS 0., Conclusions: Approximately 8 of 10 patients with normalisation of rectal bleeding and stool frequency have improvement in endoscopic disease activity, whereas approximately only half of these patients have endoscopic remission., (© 2019 John Wiley & Sons Ltd.)

Crohn's disease (CD) is an inflammatory bowel disease that can involve any region of the gastrointestinal tract. First described in 1932 as terminal ileitis or regional enteritis, it predominately involves the ileum with or without colonic involvement. Isolated colonic CD was first described in 1960 and since then the phenotypic classification of CD has evolved to stratify patients into isolated ileal, ileocolonic, or isolated colonic involvement. In the current review we evaluate the published literature regarding differences in epidemiology, natural history, pathogenesis, response to therapy, and disease monitoring, when stratified by disease location. Based on the available evidence consideration could be given to a new classification for CD, which splits it into ileum dominant (isolated ileal and ileocolonic) and isolated colonic disease. This may allow for a more optimized approach to clinical care and scientific research for CD., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Patients with Crohn's disease (CD) often have bile acid diarrhea (BAD), due to bile acid malabsorption following ileal resection (IR). Bile acid malabsorption increases production of 7α-hydroxy-4-cholesten-3-one (C4), a bile acid precursor. We investigated relationships between serum concentrations of C4 and BAD in patients with CD., Methods: We collected demographic data, serum samples, and information on the presence of diarrhea (>3 liquid bowel movements/day), as well as clinical, endoscopic, and histologic scores from 26 patients with CD and IR, 21 patients with CD without IR, and 37 patients with ulcerative colitis (UC). We compared serum concentrations of C4 and fibroblast growth factor 19 (FGF19) between groups. We performed area under the receiver operating characteristic curve (AUROC) analysis to identify the optimal cutoff C4 concentrations for the diagnosis of diarrhea attributable to bile acid malabsorption (BAD), defined as diarrhea and a serum concentration of FGF19 <60 pg/mL., Results: Patients with UC had a median serum C4 concentration of 11.8 ng/mL, whereas patients with CD and IR with ileitis (documented endoscopically) had a median concentration of 100.0 ng/mL (P compared to UC < .0001) and patients with CD and IR without ileitis had a median concentration of 51.6 ng/mL (P compared to UC < .001). Patients with CD without IR did not have a significantly higher median concentration of C4 than patients with UC (P = .71), regardless of ileitis (P = .34). When endoscopic findings were confirmed histologically, similar results were found to analyses using endoscopic findings alone. A higher proportion of patients with active UC had diarrhea (72.0% vs 0 patients with inactive UC; P < .001), but their median concentrations of C4 did not differ significantly from that of patients with inactive UC (12.1 ng/mL vs 9.7 ng/mL; P = .3). A cutoff concentration of C4 of 48.3 ng/mL or greater identified patients with diarrhea attributable to bile acid malabsorption with 90.9% sensitivity, 84.4% specificity, and an AUROC 0.94. A significantly higher proportion of patients with concentrations of C4 above this cutoff had BAD (50.0%) than below this cutoff (1.8%) (P < .001). When we analyzed only patients with diarrhea, a C4 cutoff of 48.3 ng/mL identified those with low FGF19 concentrations (<60 pg/mL) with 91% sensitivity and 95.5% specificity (AUROC, 0.99). Above this cutoff, 83.3% of patients had a serum concentration of FGF19 <60 pg/mL compared to 4.5% below this threshold (P < .0001). C4 concentrations correlated with the number of daily bowel movements (r = 0.41; P = .004) and correlated inversely with FGF19 concentrations (r = -0.72; P<.0001)., Conclusion: We observed significantly increased serum concentrations of C4 in patients with CD with IR, compared to patients with UC. A cutoff concentration of C4 above 48.3 ng/mL identifies patients with diarrhea likely attributable to bile acid malabsorption (BAD) with an AUROC value of 0.94. Increased serum levels of bile acid precursors identify patients with diarrhea and a low serum concentration of FGF19, and concentrations of C4 correlate with daily liquid bowel movements and correlate inversely with FGF19 concentrations. C4 may be a biomarker to identify patients with diarrhea attributable to bile acid malabsorption., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Monoclonal antibody (mAb) therapies have revolutionized the treatment of several chronic inflammatory diseases, including the inflammatory bowel diseases (IBD), Crohn's disease, and ulcerative colitis. While efficacious, responses to these therapies vary considerably from patient to patient, due in part to inter- and intra-individual variability in pharmacokinetics (PK) and drug exposure. The concept of personalized medicine to monitor drug exposure and to adjust dosing in individual patients is consequently gaining acceptance as a powerful tool to optimize mAb therapy for improved outcomes in IBD. This review provides a brief overview of the different mAbs currently approved or in development for the treatment of IBD, including their presumed mechanisms of action and PK properties. Specifically described are (1) the factors known to affect mAb PK and drug exposure in patients with IBD, (2) the value of population PK/pharmacodynamic (PD) modeling to identify and understand the influence of these factors on drug exposure and effect, and (3) the clinical evidence for the potential of therapeutic drug monitoring (TDM) to improve IBD outcomes in response to mAb-based therapy. Incorporation of PK/PD parameters into clinical decision support tools has the potential to guide therapeutic decision making and aid implementation of personalized medicine strategies in patients with IBD.

Background: There has been limited evaluation of the association between vedolizumab trough concentration and clinical outcomes in patients with inflammatory bowel diseases (IBD)., Aim: To perform a systematic review and meta-analysis to evaluate the potential role of therapeutic drug monitoring (TDM) for vedolizumab., Methods: Through a systematic literature search through 28 February 2019, we identified five cohort studies (558 patients, 42% with ulcerative colitis) reporting the association between vedolizumab trough concentration and clinical outcomes in patients with IBD. We calculated mean difference (MD) in vedolizumab trough concentration in patients achieving vs not achieving clinical outcomes, and qualitatively synthesized thresholds associated with favourable outcomes., Results: In patients with UC, median vedolizumab trough concentrations were consistently higher in patients achieving clinical remission (median, 14.3 μg/mL vs 10.5 μg/mL; MD, 5.1 μg/mL, 95% CI, 2.8-7.4) or endoscopic remission (median, 13.0 μg/mL vs 9.7; MD, 5.1 μg/mL, 95% CI, 2.2-7.9). In patients with CD, there was no significant difference in median vedolizumab trough concentrations in patients achieving vs not achieving clinical remission (MD, 2.0 μg/mL; 95% CI, -0.5 to 4.5) or endoscopic remission (MD, 3.6 μg/mL; 95% CI, -1.4 to 8.6). In patients with UC, week 6 vedolizumab trough concentrations ≥18.5-20.8 μg/mL, and maintenance trough concentrations ≥9.0-12.6 μg/mL were associated with favourable clinical outcomes. Antibodies to vedolizumab were reported in 1.7%-3.0% patients on maintenance therapy., Conclusion: Based on meta-analysis, patients with UC who achieve endoscopic and clinical remission have significantly higher vedolizumab trough concentration during maintenance therapy. Vedolizumab trough concentration >20 μg/mL at week 6, and >12 μg/mL during maintenance may be associated with better outcomes, though cause-effect relationship remains unclear. Prospective studies on reactive and proactive therapeutic drug monitoring of vedolizumab (vs empiric dose escalation) are warranted., (© 2019 John Wiley & Sons Ltd.)

Background and Aim: Therapeutic drug monitoring is used to optimise adalimumab therapy in patients with Crohn's disease [CD]. However, the interindividual variability in drug absorption and the quantitative effect on drug clearance of anti-adalimumab antibodies [AAA], measured with a drug-resistant assay, are unclear. We aimed to characterise adalimumab population pharmacokinetics [PopPK] and identify determinants of interindividual variability in patients with CD., Methods: In a prospective multicentre open-label cohort study in 28 patients with CD starting adalimumab therapy peak, intermediate, and trough serum samples were analysed for adalimumab and AAA concentrations using a drug resistant assay. Adalimumab concentration-time data were analysed by non-linear mixed effects modelling and were adequately described by a PopPK model with first-order absorption and one-compartment disposition with linear elimination. Clinical remission at Week 12 [W12] was defined as a Harvey-Bradshaw index ≤4., Results: The absorption rate, volume of distribution, and clearance estimates of a typical patient were respectively 0.343 /day, 7.8 L, and 0.330 L/day. A 4-fold difference in the range of adalimumab concentrations was observed 7 days after the first dose and found to be inversely correlated with baseline lean body weight [LBW], soluble tumour necrosis factor [s-TNF], and s-TNF receptor-1 whereas positive AAA and higher LBW were found to be important predictors of accelerated clearance. An adalimumab concentration at W12 of >7.3 µg/mL was significantly associated with achieving clinical remission at W12., Conclusion: Variability in subcutaneous drug absorption is an important contributor to the observed interindividual variability in adalimumab concentrations, in addition to drug clearance [ClinicalTrials.gov NCT02450513]., (Copyright © 2019 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)