Pharmacokinetic Features and Presence of Antidrug Antibodies Associate With Response to Infliximab Induction Therapy in Patients With Moderate to Severe Ulcerative Colitis

First United Arab Emirates consensus on diagnosis and management of inflammatory bowel diseases: A 2020 Delphi consensus

Ulcerative colitis and Crohn’s disease are the main entities of inflammatory bowel disease characterized by chronic remittent inflammation of the gastrointestinal tract. The incidence and prevalence are on the rise worldwide, and the heterogeneity between patients and within individuals over time is striking. The progressive advance in our understanding of the etiopathogenesis coupled with an unprecedented increase in therapeutic options have changed the management towards evidence-based interventions by clinicians with patients. This guideline was stimulated and supported by the Emirates Gastroenterology and Hepatology Society following a systematic review and a Delphi consensus process that provided evidence- and expert opinion-based recommendations. Comprehensive up-to-date guidance is provided regarding diagnosis, evaluation of disease severity, appropriate and timely use of different investigations, choice of appropriate therapy for induction and remission phase according to disease severity, and management of main complications.

Optimization of azathioprine dose in combined treatment with anti-TNF-alpha in inflammatory bowel disease

INTRODUCTION

The dose of thiopurine drugs in combined treatments with anti-TNF in inflammatory bowel disease (IBD) has not been clearly established. The purpose of this study is to assess whether the dose of azathioprine influences clinical and biochemical response/remission rates, and anti-TNF drug levels/antibody formation.

MATERIAL AND METHODS

Patients with IBD on combined maintenance treatment with azathioprine and infliximab or adalimumab were selected. Based on the dose of azathioprine, two groups were defined (standard: 2-2.5mg/kg/day; and decreased: less than 2mg/kg/day).

RESULTS

In the IFX group, there were no statistically significant differences (p=0.204) in the rates of remission (39% vs 41.3%), response (10% vs 21.7%) or failure (51.5% vs 37%) depending on the dose of thiopurine drugs. No differences were found between AZA-dose dependent IFX levels (2.46 vs 3.21μg/mL; p=0.211). In the adalimumab group, there were no statistically significant differences (p=0.83) in the rates of remission (66% vs 56%), response without remission (15.38% vs 25%) or failure (18% vs 18%) depending on the dose of thiopurines. With respect to ADA-levels, no differences were found in both groups (7.69 vs 8.23μg/mL; p=0.37).

CONCLUSION

In our experience, no statistically significant differences were found in either anti-TNF levels or clinical-biological response/remission rates based on doses of azathioprine.

Optimizing biologic therapy in IBD: how essential is therapeutic drug monitoring?

Proposed treatment targets for the management of inflammatory bowel disease (IBD) have moved beyond symptomatic improvement towards more objective end points, such as healing of the intestinal mucosa. This treat-to-target approach has been associated with improved disease outcomes such as diminished bowel damage, surgery and hospitalizations. Many patients with IBD require biologic therapy to achieve and maintain clinical and endoscopic remission, and antitumour necrosis factor antibodies remain the first-line biologic therapy in most areas of the world. Unfortunately, up to one-third of patients receiving this treatment are primary non-responders, and some patients that show an initial response can also lose response over time. Therapeutic drug monitoring (TDM) has been suggested as a useful tool to manage patients on antitumour necrosis factor treatment, including monitoring for dose escalation, de-escalation or to switch treatment. In this Perspective, we aim to summarize evidence and guidelines related to TDM in IBD management and also discuss potential strategies to optimize biologic treatment where TDM is not available.

Thiopurines in Pediatric Inflammatory Bowel Disease: Current and Future Place

Thiopurines have been widely used to maintain steroid-free remission in children with inflammatory bowel disease (IBD). However, within the expanding treatment armamentarium, the role of these non-selective immunomodulators has been questioned, especially in pediatric patients, who often present with a more aggressive disease course, which can impact growth and development. The less favorable safety but also inferior efficacy profile associated with thiopurines, in contrast to the newer biological therapies, has interfered with their use. The future place of thiopurines in the management of childhood IBD, therefore, needs revisiting. This review provides a practical overview on the historical and current use of thiopurines in pediatric IBD with specific attention for thiopurine S-methyltransferase testing and monitoring of thiopurine metabolite levels as an approach to improve outcomes. We also give a personal expert opinion on the future role of these drugs in childhood IBD.

Optimization of biologics to reduce treatment failure in inflammatory bowel diseases

Moderate to severe inflammatory bowel disease patients can fail to respond to conventional therapy and/or to biologic treatment. In the era of TNFα antagonists and other non-anti-TNF biologic drugs, it is important to review the literature on biologic treatment failure, which could be defined as primary non-response, secondary loss of response and intolerance. Therapeutic drug monitoring (TDM), that is, drug trough level and antidrug antibodies, should enable to determine the mechanisms of treatment failure and to optimize drug efficacy. There is a consensus on reactive TDM at the time of loss of response. Proactive TDM could be of interest during induction and/or maintenance, but randomized controlled trials are required.

Therapeutic thresholds and mechanisms for primary non-response to infliximab in inflammatory bowel disease

BACKGROUND

Primary non-response to infliximab (IFX) inherits a poor prognosis in inflammatory bowel disease (IBD). We explored underlying mechanisms and therapeutic thresholds in an effort to provide basis for optimizing therapy.

METHODS

A prospectively followed cohort of 166 IBD patients having received standard IFX induction therapy (5 mg/kg at weeks 2, 6, and 14) had trough IFX and anti-IFX antibodies (Abs) retrospectively assessed at weeks 2 (n = 148) and 6 (n = 108). Circulating TNFα was measured in matched primary non-responders (n = 29) and responders (n = 21) at baseline and weeks 6 and 14. Clinical outcome at week 14 was supported by disease activity scores in half of patients.

RESULTS

In all, 18 patients (11%) had primary non-response. Infliximab was consistently lower throughout the induction phase in non-responders as compared to responders (Week 2: IFX median 18.9 μg/mL vs. 23.3, p < .05. Week 6: 8.4 vs. 17.0, p < .05). Optimal IFX thresholds associated with response was 22.9 μg/mL at week 2 (sensitivity 51%, specificity 80%, AUC_ROC 0.67, p < .05) and 11.8 at week 6 (72%, 77%, 0.71, p < .05). Anti-IFX Abs occurred in 28% of primary non-responders and associated with low IFX and treatment failure (OR 13.7 [2.8-67.5], p < .01). Markers of disease activity (disease activity scores, albumin, CRP) also associated with low IFX. Circulating TNFα was higher throughout induction in non-responders with ulcerative colitis but not Crohn's disease.

CONCLUSION

IBD patients with primary IFX failure generally have lower IFX trough than responders during early induction phase. Pharmacokinetic failure seems common in ulcerative colits, whereas pharmacodynamic failure appears common in Crohn's disease.

Exposure-Response Relationship of Certolizumab Pegol and Achievement of Low Disease Activity and Remission in Patients With Rheumatoid Arthritis

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.

Therapeutic Drug Monitoring of Biologics During Induction to Prevent Primary Non-Response

Biologic therapies have revolutionized the management of inflammatory bowel disease [IBD], but primary and secondary non-responses occur in a significant proportion of patients. Therapeutic drug monitoring [TDM] now has an established role in the treatment algorithm for managing secondary loss of response to anti-tumour necrosis factor [anti-TNF] agents during maintenance therapy. Data to support the use of TDM in the management of secondary loss of response to vedolizumab and ustekinumab are emerging. The potential to prevent primary non-response to biologic agents during induction is of equal, and potentially greater, clinical importance. Again, most data supporting the use of 'proactive' TDM during induction pertains to the use of anti-TNF agents, but signals of efficacy for the use of TDM during induction with other biologic classes are now appearing. This review aims to summarize data on the use of TDM during induction to prevent pharmacokinetic primary non-response to all three classes of biologic therapy currently available for the treatment of IBD.

How, When, and for Whom Should We Perform Therapeutic Drug Monitoring?

The implementation of therapeutic drug monitoring (TDM) in the inflammatory bowel disease practice has evolved over the years. In the early days, the focus was merely on measuring and reporting drug concentrations. Later, these concentrations were considered in light of target concentrations that are related to clinical response. This not only allowed passively predicting a patient's future response, but it also triggered physicians and pharmacists to actively use the information to optimize the drug dosage to induce and maintain a clinical response in the future. Although reactive TDM, testing at time of loss of response, is widely accepted in practice, especially for anti-tumor necrosis factor antibodies, there are less data for the other monoclonal antibodies belonging to other classes. Besides reactive testing, there is a movement toward proactively adjusting biologic dosing to prevent loss of response, in keeping with the tight control philosophy of inflammatory bowel disease care. This review highlights the various assays available to measure drug concentrations and antidrug antibodies, as well as algorithmic approaches to TDM, the unmet needs and required studies to enable pharmacokinetics principles to be applied in the future.

Usefulness of therapeutic drug monitoring of infliximab during the induction period in patients with inflammatory bowel disease

INTRODUCTION

previous studies have shown that higher infliximab trough levels are associated with favorable short-term and long-term therapeutic outcomes in inflammatory bowel disease. There is a need to determine which patients could benefit from proactive therapeutic drug monitoring in the induction phase. The aim of this study was to evaluate the pharmacokinetic variability of infliximab, determine the factors associated with achieving target infliximab trough levels in the induction phase and analyze the clinical and biochemical response at week 26 of treatment.

PATIENTS AND METHODS

a retrospective observational study was performed of patients with inflammatory bowel disease and data available on serum levels of infliximab during the induction period. The percentage of patients that achieved target infliximab trough levels at week 6 was determined. Clinical remission and response and biochemical remission were evaluated at week 26.

RESULTS

thirty patients were included and only 13 (43.3 %) had infliximab trough levels > 15 µg/mL at week 6. A clinical response was observed during the maintenance period in 71.4 % of patients, their infliximab levels were significantly higher than in non-responders (6.3 µg/mL [IQR: 6.7] vs 1.0 µg/mL [IQR: 5.0], respectively; p = 0.016). Likewise, 53.6 % of patients achieved biochemical remission (responders 6.2 µg/mL [IQR: 5.2] vs non-responders 3.2 µg/mL [IQR: 5.0]; p = 0.031).

CONCLUSION

less than half of patients had target infliximab levels during the induction period. Therapeutic drug monitoring during this period is related to the achievement of therapeutic levels of infliximab and may lead to a better clinical response in these patients.

Reversal of anti-drug antibodies against tumor necrosis factor inhibitors with addition of immunomodulators: A systematic review and meta-analysis

BACKGROUND

The development of anti-drug antibodies (ADA) to tumor necrosis factor (TNF-α) inhibitors is a significant result contributing to the loss of clinical response in inflammatory bowel disease (IBD).

AIMS

We performed a systematic review and meta-analysis to assess whether the addition of immunomodulators to TNF-α inhibitors lead to reversal of antibody formation in TNF-α inhibitor-treated IBD patients.

METHODS

We conducted a comprehensive search of electronic databases from inception through October 2018 in order to identify specific studies describing clinical response in IBD patients following the addition of immunomodulators (methotrexate or thiopurines) to TNF-α inhibitors. Clinical response was expressed as an improvement of symptoms, with a noted decrease or complete elimination of ADA against TNF-α inhibitors. The meta-analysis was performed using the DerSimonian and Laird random-effect model.

RESULTS

Four studies were included in our final meta-analysis, which reported outcomes in 72 patients receiving TNF-α inhibitors. Forty-nine of the seventy-two (68%) patients received either methotrexate (19) or thiopurines (30). The average follow up period was 13.5 months. The overall pooled clinical response was 73.86% (95% confidence interval [CI] = 47.36-94.38, I² = 60.77%).

CONCLUSION

In our meta-analysis, addition of immunomodulators to TNF-α inhibitors was shown to restore the clinical response in 74% of the patients by either decreasing or completely eliminating anti-drug antibody levels. Further long-term multicenter studies are needed to validate these findings.

Improved Population Pharmacokinetic Model for Predicting Optimized Infliximab Exposure in Pediatric Inflammatory Bowel Disease

BACKGROUND

Many pediatric patients with inflammatory bowel disease (IBD) lose response to infliximab (IFX) within the first year, and achieving a minimal target IFX trough concentration is associated with higher remission rates and longer durability. Population pharmacokinetic (PK) modeling can predict trough concentrations for individualized dosing. The object of this study was to refine a population PK model that accurately predicts individual IFX exposure during maintenance therapy using longitudinal real-practice data.

METHODS

We exported data from the electronic health records of pediatric patients with IBD treated with originator IFX at a single center between January 2011 and March 2017. Subjects were divided into discovery and validation cohorts. A population PK model was built and then validated.

RESULTS

We identified 228 pediatric patients with IBD who received IFX and had at least 1 drug concentration measured, including 135 and 93 patients in the discovery and validation cohorts, respectively. Weight, albumin, antibodies to IFX (ATI) detected by a drug-tolerant assay, and erythrocyte sedimentation rate (ESR) were identified as covariates significantly associated with IFX clearance and incorporated into the model. The model exhibited high accuracy for predicting target IFX trough concentrations with an area under the receiver operating characteristic curve (AUROC) of 0.86 (95% confidence interval [CI], 0.81-0.91) for population-based predictions without prior drug-level input. Accuracy increased further for individual-based predictions when prior drug levels were known, with an AUROC of 0.93 (95% CI, 0.90-0.97).

CONCLUSIONS

A population PK model utilizing weight, albumin, ordinal drug-tolerant ATI, and ESR accurately predicts IFX trough concentrations during maintenance therapy in real-practice pediatric patients with IBD. This model, which incorporates dynamic clinical information, could be used for individualized dosing decisions to increase response durability.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) of unknown etiology, probably caused by a combination of genetic and environmental factors. The treatment of patients with active UC depends on the severity, localization and history of IBD medication. According to the classic step-up approach, treatment with 5-aminosalicylic acid compounds is the first step in the treatment of mild to moderately active UC. Corticosteroids, such as prednisolone are used in UC patients with moderate to severe disease activity, but only for remission induction therapy because of side effects associated with long-term use. Thiopurines are the next step in the treatment of active UC but monotherapy during induction therapy in UC patients is not preferred because of their slow onset. Therapeutic drug monitoring (TDM) of the pharmacologically active metabolites of thiopurines, 6-thioguanine nucleotide (6-TGN), has proven to be beneficial. Thiopurine S-methyltransferase (TMPT) plays a role in the metabolic conversion pathway of thiopurines and exhibits genetic polymorphism; however, the clinical benefit and relevance of TPMT genotyping is not well established. In patients with severely active UC refractory to corticosteroids, calcineurin inhibitors such as ciclosporin A (CsA) and tacrolimus are potential therapeutic options. These agents usually have a rather rapid onset of action. Monoclonal antibodies (anti-tumor necrosis factor [TNF] agents, vedolizumab) are the last pharmacotherapeutic option for UC patients before surgery becomes inevitable. Body weight, albumin status and antidrug antibodies contribute to the variability in the pharmacokinetics of anti-TNF agents. Additionally, the use of concomitant immunomodulators (thiopurines/methotrexate) lowers the rate of immunogenicity, and therefore the concomitant use of anti-TNF therapy with an immunomodulator may confer some advantage compared with monotherapy in certain patients. TDM of anti-TNF agents could be beneficial in patients with primary nonresponse and secondary loss of response. The potential benefit of applying TDM during vedolizumab treatment has yet to be determined.

Factors Influencing Drug Disposition of Monoclonal Antibodies in Inflammatory Bowel Disease: Implications for Personalized Medicine

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.

Comparable Long-Term Outcomes of Cyclosporine and Infliximab in Patients With Steroid-Refractory Acute Severe Ulcerative Colitis: A Meta-Analysis

Background: In steroid-refractory acute severe ulcerative colitis (ASUC), cyclosporine (CYS) or infliximab (IFX) may be considered as a second-line alternative to avoid colectomy. There are short-term data reported, but until now, there is no meta-analysis regarding long-term outcomes of CYS and IFX in patients with ASUC.

Aim: To compare long-term efficacy and safety of CYS and IFX in a meta-analysis.

Methods: Three electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials) were searched for studies which compared CYS vs. IFX in adults with ASUC. Long-term colectomy-free rate from 1 to 10 years during CYS or IFX therapy was collected, last updated up to 22nd May 2019. Primary outcome was long-term colectomy-free rate, secondary outcomes were adverse events (AE), serious adverse events (SAE), and mortality. Long-term colectomy-free survival and safety measures were pooled with the random-effect model. Odds ratios (OR) with 95% confidence intervals (CI) were calculated.

Results: Data from 1,607 patients in 15 trials were extracted. In the first 3 years, pooled OR for colectomy-free survival was higher with IFX than with CYS (OR = 1.59, 95% CI: 1.11–2.29, p = 0.012; OR = 1.57, 95% CI: 1.14–2.18, p = 0.006; and OR = 1.75, 95% CI: 1.08–2.84, p = 0.024; at 1, 2, and 3 years, respectively). However, the significant difference remained undetected from the fourth year of follow-up and in subgroup of RCTs (OR = 1.35, 95% CI: 0.90–2.01, p = 0.143; OR = 1.41, 95% CI: 0.94–2.12, p = 0.096; and OR = 1.34, 95% CI: 0.89–2.00, p = 0.157; at 1, 2, and 3 years, respectively). No significant difference was detected regarding adverse events, serious adverse events and mortality between the groups. The neutral associations proved to be underpowered with trial sequential analysis.

Conclusion: However observational studies show IFX as a better choice, according to the RCTs, choosing either CYS or IFX as rescue therapy for ASUC, the long-term outcomes are not different, although further large RCTs are warranted.

Management of Acute Severe Colitis in the Era of Biologicals and Small Molecules

Acute severe ulcerative colitis (ASUC) is a medical emergency which occurs in about 20%–30% of patients with ulcerative colitis during their lifetime, and does carry a mortality risk of 1%. The management of inflammatory bowel diseases has evolved with changes in objective patient monitoring, as well as the availability of new treatment options with the development of new biological and small molecules; however, data is limited regarding their use in the context of ASUC. This review aims to discuss the emerging data regarding biologicals and small molecules therapies in the context of ASUC.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

Inpatient Management of Acute Severe Ulcerative Colitis

Acute severe ulcerative colitis (ASUC) is a potentially life-threatening presentation of ulcerative colitis that in nearly all cases requires inpatient management and coordinated care from hospitalists, gastroenterologists, and surgeons. Even with ideal care, a substantial proportion of patients will ultimately require colectomy, but most patients can avoid surgery with intravenous corticosteroid treatment and if needed, appropriate rescue therapy with infliximab or cyclosporine. In-hospital management requires not only therapies to reduce the inflammation at the heart of the disease process, but also to avoid complications of the disease and its treatment. Care for ASUC must be anticipatory, with patient education and evaluation starting at the time of admission in advance of the possible need for urgent medical or surgical rescue therapy. Here we outline a general approach to the treatment of patients hospitalized with ASUC, highlighting the common pitfalls and critical points in management.

Serum γ-globulin and albumin concentrations predict secondary loss of response to anti-TNFα in inflammatory bowel disease patients

BACKGROUND

Loss of response to anti-TNFα treatment occurs frequently in IBD- patients. We evaluatedthe predictive value of serum albumin and γ-globulin concentrations for treatment failure.

METHODS

Prospectively, all patients treated for the first time with either infliximab or adalimumab for IBD between 2007 and 2018 were included. All patients were tested for serum albumin and γ-globulin concentrations and were followed up until June 2018.

RESULTS

128 patients (95 Crohn's disease, 67 females, age 40.1 ± 13.7 years) were included in the study. 81patients (63.3%) received infliximab and 47 (36.7%) adalimumab first line. Eight patients (6.3%) were primary non-responders, 50 patients (39.0%) showed a sustained clinical remission and 70 patients (54.7%) developed a secondary loss of response. Meantime to develop secondary loss of response was 24.5 ± 20.5 months. Albumin serum concentrations in the clinical response group were significantly higher than in the secondary loss of response group (39.8 ± 5.7 g/L vs. 35.0 ± 5.4 g/L). γ-globulin serum concentrations in the sustained response group were significantly lower than in the secondary loss of response group (11.8 ± 2.8 g/L vs. 14.7 ± 4.5 g/L). Hypoalbuminemia and hypergammaglobulinemia were associated with the loss of response. Immunosuppressant co-medication in patients with high γ-globulin serum concentrations reduced the risk of secondary loss of response.

CONCLUSION

Low albumin and increased γ-globulin serum concentrations are strongly associated with a higher risk for loss of response to an anti-TNFα treatment. Increased serum γ-globulin concentrations may have a higher risk to produce anti-drug antibodies or a different phenotype of disease less responsive to anti-TNFα treatment.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

Practical Aspects of Proactive TDM for Anti-TNF Agents in IBD: Defining Time Points and Thresholds to Target

Serum biologic drug concentrations have been associated with favorable therapeutic outcomes in inflammatory bowel diseases, while low or undetectable drug levels have been linked to immunogenicity and treatment failure. Therapeutic drug monitoring (TDM) in the context of clinical relapse can guide decision making and is supported by professional groups. Proactive TDM consists of measurement of trough concentration with the goal of optimizing drug concentration in patients with clinical response/remission. Recent findings suggest that this approach can improve the efficacy of antitumor necrosis factor agents (anti-TNF). In this article, we summarize the rationale for proactive TDM for anti-TNF agents in practice, identify limitations in this evidence base, and provide practical advice for use in the clinic.

Clinical Pharmacokinetics and Pharmacodynamics of Infliximab in the Treatment of Inflammatory Bowel Disease

Infliximab was the first monoclonal antibody to be approved for the treatment of pediatric and adult patients with moderately to severely active Crohn's disease (CD) and ulcerative colitis (UC). It has been shown to induce and maintain both clinical remission and mucosal healing in pediatric and adult patients with inflammatory bowel disease (IBD) who are unresponsive or refractory to conventional therapies. The administration of infliximab is weight-based and the drug is administered intravenously. The volume of distribution of infliximab is low and at steady state ranges from 4.5 to 6 L. Therapeutic monoclonal antibodies, such as immunoglobulins, are cleared from the circulation primarily by catabolism. Median infliximab half-life is approximately 14 days. Infliximab concentration-time data in patients with CD and UC have been shown to be highly variable within an individual patient over time and between individuals by multiple population pharmacokinetic models. Covariates that have been identified to account for a part of the observed inter- and intra-individual variability in clearance are the presence of antidrug antibodies, use of concomitant immunomodulators, degree of systemic inflammation, serum albumin concentration, and body weight, which can affect the pharmacodynamic response. This article provides a comprehensive review of the clinical pharmacokinetics and pharmacodynamics of infliximab, as well as the role of therapeutic drug monitoring in the treatment of IBD.

An approach to acute severe ulcerative colitis

Introduction: Despite the introduction of novel therapies and treatment strategies for ulcerative colitis (UC), many patients develop acute, severe episodes, warranting prompt care and aggressive management. There is a significant unmet need to improve outcomes in these patients. Clinicians must be able to identify those that will have worse prognosis and plan an aggressive therapy with an early/proactive adjustments in management if needed.Areas covered: The aim of this review is to evaluate the most recent evidence on the assessment and management of patients with acute severe ulcerative colitis. We searched the mainstream literature search engines for the most recent evidence on diagnosis and management of acute UC.Expert Opinion: The approach to patients with severe UC includes clinical and endoscopic assessment of disease severity and ruling out over-infections. While intravenous corticosteroids remain the first line therapy for acute severe colitis, many patients do not respond and require escalation to calcineurin inhibitors or infliximab, and may ultimately require colectomy. Even though several novel therapies are available or in development, their role in acute severe episodes of colitis is unknown.

Achieving Mucosal Healing in Inflammatory Bowel Diseases: Which Drug Concentrations Need to Be Targeted?

Biologicals introduced a major shift in the treatment of patients suffering from inflammatory bowel diseases. Despite providing a tight disease control for many patients, a considerable proportion of patients will fail to respond favorably to treatment or will lose response over time. Therapeutic drug monitoring emerged as a valuable tool to guide clinical decision making as serum drug concentrations have been linked to outcomes. Focusing on mucosal healing as the ultimate treatment goal, different drug concentration thresholds to achieve this outcome have been identified in the literature and are summarized in this review. For therapeutic drug monitoring to be successful in guiding clinical decision making, the used assay, the sampling time point, and the outcome that is aimed for should be taken into account when interpreting drug concentration thresholds. Awareness of these essential aspects among clinicians will improve the implementation of therapeutic drug monitoring and aid in making an evidence‐based decision.

Tumor necrosis factor-mediated disposition of infliximab in ulcerative colitis patients

Ulcerative Colitis (UC) is an inflammatory bowel disease typically affecting the colon. Patients with active UC have elevated tumor necrosis factor (TNF) concentrations in serum and colonic tissue. Infliximab is a monoclonal antibody directed against TNF and binds with high affinity. Target-mediated drug disposition (TMDD) is reported for monoclonal antibodies meaning that their pharmacokinetics are affected by high target affinity. Here, a TMDD model is proposed to describe the interaction between infliximab and TNF in UC patients. Data from 20 patients with moderate to severe UC was used. Patients received standard infliximab induction therapy (5 mg kg⁻¹) at week 0, followed by infusions at week 2 and 6. IFX, anti-drug antibodies and TNF serum concentrations were measured at day 0 (1 h after infusion), 1, 4, 7, 11, 14, 18, 21, 28 and 42. A binding model, TMDD model, and a quasi-steady state (QSS) approximation were evaluated using nonlinear mixed effects modeling (NONMEM). A two-compartment model best described the concentration–time profiles of infliximab. Typical clearance of infliximab was 0.404 L day⁻¹ and increased with the presence of anti-drug antibodies and with lower albumin concentrations. The TMDD-QSS model best described the pharmacokinetic and pharmacodynamics data. Estimate for TNF baseline (B_max was 19.8 pg mL⁻¹ and the dissociation constant (K_ss) was 13.6 nM. This model could eventually be used to investigate the relationship between suppression of TNF and the response to IFX therapy.

Intensified Infliximab Induction is Associated with Improved Response and Decreased Colectomy in Steroid-Refractory Paediatric Ulcerative Colitis

BACKGROUND

Infliximab pharmacokinetics in steroid-refractory [SR] ulcerative colitis [UC] suggest a need for higher dosing, but data concerning efficacy of intensification in this setting are lacking in children and inconsistent overall.

METHODS

Paediatric patients [N = 125] treated with infliximab for SR or steroid-dependent UC were retrospectively reviewed. Outcomes [clinical response and remission, colectomy, mucosal healing, safety] with standard vs intensified induction [mean induction dose ≥7 mg/kg or interval ≤5 weeks between doses 1 and 3] were compared.

RESULTS

Among 125 patients [median age 14 years, median UC duration 0.7 years, 74 SR], 73 [58%] received standard induction and 52 [42%] received intensified induction. Overall, 73 [58%] achieved remission (judged by physician global assessment [PGA] and paediatric UC activity index [PUCAI]≤10]. Among patients in remission, 7 [10%] experienced secondary loss of response by a median of 0.7 [IQR 0.4-1.0] years. Of the 74 SR patients, 17 [23%] underwent colectomy, and of the 51 steroid-dependent patients, 12 [24%] underwent colectomy. Intensified induction in SR patients was associated with a higher chance of remission (hazard ratio [HR] 3.2, p = 0.02) and a lower chance of colectomy [HR 0.4, p = 0.05], but did not improve outcomes in steroid-dependent patients. During follow-up, 46/73 [63%] patients in remission had regimen individualization, with similar rates of return to standard dosing after 1 year between those with initial intensified or standard induction. Follow-up endoscopy, performed in 35/73 patients in remission, demonstrated mucosal healing for 66%. Adverse events were rare, despite use of intensified regimens.

CONCLUSIONS

These data suggest a benefit from intensified infliximab induction specifically among children with steroid-refractory UC. Prospective studies comparing dosing regimens and incorporating therapeutic drug monitoring should be undertaken.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Actual Anti-TNF Trough Levels Relate to Serum IL-10 in Drug-Responding Patients With Crohn's Disease

BACKGROUND

Patients with Crohn's disease (CD) responding to anti-tumor necrosis factor (anti-TNF) show great variability in serum drug levels, even within the therapeutic range. We aimed at exploring the role of inflammatory, genetic, and bacterial variables in relation to anti-TNF through levels in CD patients.

METHODS

Consecutive CD patients receiving stable doses of infliximab or adalimumab were included. Clinical and analytical parameters were recorded. Cytokine response, bacterial DNA translocation, and several immune-related genes' genotypes were evaluated, along with serum through anti-TNF drug levels. A linear regression analysis controlled by weight and drug regimen was performed.

RESULTS

One hundred nineteen patients were initially considered. Five patients on infliximab and 2 on adalimumab showed antidrug antibodies in serum and were excluded. One hundred twelve patients were finally included (62 on infliximab, 50 on adalimumab). Fourteen patients on infliximab and 15 on adalimumab (22.6% vs 30%, P = 0.37) were receiving an intensified drug regimen. C-reactive protein (CRP), fecal calprotectin, Crohn's Disease Activity Index, leukocyte count, and albumin levels in plasma were not significantly associated with infliximab or adalimumab levels in the multivariate analysis. Serum interleukin-10 (IL-10) levels were directly related to infliximab (Beta = 0.097, P < 0.0001) and adalimumab levels (Beta = 0.069, P = 0.0241). The best multivariate regression model explaining the variability of serum infliximab and adalimumab levels included IL-10. Predicted drug levels by this model robustly fitted with actual drug levels (R2 = 0.841 for infliximab, R2 = 0.733 for adalimumab).

CONCLUSION

Serum IL-10 is significantly related to serum anti-TNF levels in CD patients, showing how the disposition of anti-TNF drugs is significantly influenced by the degree of immunological activation.

Therapeutic drug monitoring in inflammatory bowel disease: for every patient and every drug?

PURPOSE OF REVIEW

The current review provides an updated overview on the role of therapeutic drug monitoring (TDM) of biological therapies in inflammatory bowel disease (IBD). We examine the data behind TDM for the antitumor necrosis factor agents, vedolizumab and ustekinumab, in patients with IBD. In addition, we discuss reactive vs. proactive TDM.

RECENT FINDINGS

There is a positive correlation between biologic drug concentrations and favorable therapeutic outcomes in IBD, although the majority of data refer to antitumor necrosis factor therapy. Reactive TDM has rationalized the management of patients with IBD with loss of response to biological therapy. Moreover, reactive TDM of infliximab has been proven to be more cost-effective when compared with empiric dose optimization. Preliminary data suggest that proactive TDM of infliximab and adalimumab applied in patients with clinical response/remission is associated with better therapeutic outcomes compared with standard of care (empiric treatment and/or reactive TDM).

SUMMARY

For all biologics in IBD, there is a positive correlation between drug concentrations and favorable therapeutic outcomes. Reactive TDM is the new standard of care for optimizing biologic therapies in IBD, whereas recent data suggest an important role of proactive TDM for optimizing antitumor necrosis factor therapy in IBD.

Systematic Review and Meta-analysis: Optimal Salvage Therapy in Acute Severe Ulcerative Colitis

BACKGROUND

Infliximab is an effective salvage therapy in acute severe ulcerative colitis; however, the optimal dosing strategy is unknown. We performed a systematic review and meta-analysis to examine the impact of infliximab dosage and intensification on colectomy-free survival in acute severe ulcerative colitis.

METHODS

Studies reporting outcomes of hospitalized steroid-refractory acute severe ulcerative colitis treated with infliximab salvage were identified. Infliximab use was categorized by dose, dose number, and schedule. The primary outcome was colectomy-free survival at 3 months. Pooled proportions and odds ratios with 95% confidence intervals were reported.

RESULTS

Forty-one cohorts (n = 2158 cases) were included. Overall colectomy-free survival with infliximab salvage was 79.7% (95% confidence interval [CI], 75.48% to 83.6%) at 3 months and 69.8% (95% CI, 65.7% to 73.7%) at 12 months. Colectomy-free survival at 3 months was superior with 5-mg/kg multiple (≥2) doses compared with single-dose induction (odds ratio [OR], 4.24; 95% CI, 2.44 to 7.36; P < 0.001). However, dose intensification with either high-dose or accelerated strategies was not significantly different to 5-mg/kg standard induction at 3 months (OR, 0.70; 95% CI, 0.39 to 1.27; P = 0.24) despite being utilized in patients with a significantly higher mean C-reactive protein and lower albumin levels.

CONCLUSIONS

In acute severe ulcerative colitis, multiple 5-mg/kg infliximab doses are superior to single-dose salvage. Dose-intensified induction outcomes were not significantly different compared to standard induction and were more often used in patients with increased disease severity, which may have confounded the results. This meta-analysis highlights the marked variability in the management of infliximab salvage therapy and the need for further studies to determine the optimal dose strategy.

A comparison of short-term therapeutic efficacy between infliximab and tacrolimus for moderate to severe ulcerative colitis

INTRODUCTION

Both infliximab (IFX) and tacrolimus (Tac) are effective for inducing clinical remission in patients with ulcerative colitis (UC). However, no randomized study has addressed the relative efficacies of IFX and Tac for patients with moderate to severe UC. This study aimed to conduct a retrospective study on the relative efficacy of IFX and Tac in patients with moderate to severe UC, using an inverse probability of treatment weighting (IPTW) technique to adjust background factors statistically.

METHODS

Between July 2009 and March 2016, data obtained from 122 patients with moderate to severe UC who were treated with either IFX (n = 58) or Tac (n = 64) were analyzed retrospectively. We compared the short-term therapeutic efficacy between the IFX group and Tac group using IPTW technique.

RESULTS

The clinical remission rate at 14 weeks after treatment was 37.9% (22/58) in the IFX group and 50% (32/64) in the Tac group, respectively. The efficacy of IFX and Tac for clinical remission rate was not different according to univariate (Odds ratio [OR] 1.64, 95% confidence interval [CI] 0.80-3.37 P = 0.18) and multivariate analyses (OR 2.19, 95% CI 0.85-5.61, P = 0.10). After the background and confounders factors were adjusted by using IPTW based on propensity score, the efficacy of IFX and Tac for clinical remission rate was not differed statistically (OR, 1.483; 95% CI, 0.581-3.785; P = 0.409) Conclusion. IFX and Tac have equivalent short-term efficacies for induction in patients with moderate to severe UC.

Systematic Review: Efficacy and Safety of Accelerated Induction Regimes in Infliximab Rescue Therapy for Hospitalized Patients with Acute Severe Colitis

BACKGROUND

Pharmacokinetic data suggest that standard induction dosing schedules may not be sufficient in patients with acute severe colitis (ASUC). Hence, intensified induction regimes are increasingly used in the rescue treatment of hospitalized patients with ASUC to avoid the need for colectomy although the evidence for this is uncertain.

AIM

To conduct a systematic review of short- and long-term efficacy outcomes from accelerated infliximab induction studies.

METHODS

Systematic search of relevant databases (MEDLINE, EMBASE, Cochrane Database of Systematic Reviews) and relevant conference proceedings (Digestive Diseases Week, European Colitis and Crohn's Organisation Congress, United European Gastroenterology Week) was done.

RESULTS

We identified ten relevant studies with a total of 705 patients, of whom 308 received an intensified infliximab regime. Pooled analysis showed no difference in short-term or long-term colectomy rates in those receiving accelerated induction regimes when compared to standard induction. No significant differences in complication rates were identified.

CONCLUSIONS

The available uncontrolled studies so far do not suggest short-term or long-term benefit in using accelerated induction in hospitalized ASUC. The overall poor quality of available studies with confounding variables indicates the need for a randomized controlled trial with personalized risk stratification.

Early vedolizumab trough levels at induction in inflammatory bowel disease patients with treatment failure during maintenance

BACKGROUND

Vedolizumab (VDZ) is effective as an induction and maintenance treatment for Crohn's disease and ulcerative colitis, but, as observed with antitumour necrosis factor-α (anti-TNFα) agents, some patients are nonetheless experiencing loss of response.

OBJECTIVE

The aim of this study was to investigate the impact of the pharmacokinetics of VDZ during induction on long-term treatment response.

PATIENTS AND METHODS

This study focused on a single cohort of 103 inflammatory bowel disease patients treated with VDZ. VDZ trough levels (TLs) were measured by enzyme-linked immunosorbent assay (n=536 samples), and thereafter correlated to clinical, biological, endoscopic and serological data. For patients exposed previously to infliximab, antibodies to infliximab were measured at baseline. On the basis of the outcome at the end of follow-up, patients were then categorized into long-term response, optimized and treatment failure groups.

RESULTS

During VDZ induction, at week 6, inflammatory bowel disease patients with long-term response had higher TLs compared with patients in the treatment failure group (33 vs. 24 µg/ml, P=0.02). A cut-off TL of 28 µg/ml predicted a sustained response in the follow-up with an area under curve of 0.723 (95% confidence interval=0.567-0.878, P=0.02). Patients with mucosal healing in maintenance had higher TLs at week 6 (41.65 µg/ml) compared with patients with mild (26 µg/ml) or severe endoscopic activity (20.8 µg/ml), P=0.009. Positive perinuclear antineutrophil cytoplasmic antibody serology was associated with lower TLs. Patients previously exposed to anti-TNFα had lower TLs than naive patients (22.5 vs. 36 µg/ml, P=0.03) without any impact of detectable antibodies to infliximab. Finally, the presence of an immunomodulator at induction did not impact on VDZ TLs at induction.

CONCLUSION

We confirmed that a drug exposure-efficacy association was found early on at induction. This study emphasizes that previous exposure to anti-TNFα and positive perinuclear antineutrophil cytoplasmic antibody serology are important factors influencing VDZ TLs at induction.

ACG Clinical Guideline: Ulcerative Colitis in Adults

Ulcerative colitis (UC) is an idiopathic inflammatory disorder. These guidelines indicate the preferred approach to the management of adults with UC and represent the official practice recommendations of the American College of Gastroenterology. The scientific evidence for these guidelines was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process. In instances where the evidence was not appropriate for GRADE, but there was consensus of significant clinical merit, "key concept" statements were developed using expert consensus. These guidelines are meant to be broadly applicable and should be viewed as the preferred, but not only, approach to clinical scenarios.

Optimising infliximab induction dosing for patients with ulcerative colitis

AIMS

The therapeutic failure of infliximab therapy in patients with ulcerative colitis remains a challenge even 2 decades after its approval. Therapeutic drug monitoring (TDM) has shown value during maintenance therapy, but induction therapy has still not been explored. Patients may be primary nonresponders or underexposed with the standard dosing regimen. We aimed to: (i) develop a population pharmacokinetic-pharmacodynamic model; (ii) identify the best exposure metric that predicts mucosal healing; and (iii) build an exposure-response (ER) model to demonstrate model-based dose finding during induction therapy with infliximab.

METHODS

Data were retrospectively collected from a clinical database. A total of 583 samples, from 204 patients, was used to develop a population pharmacokinetic model to generate exposure metrics for subsequent ER modelling. A subset of 159 patients was used to develop a logistic regression ER model, describing the relationship between infliximab exposure and ordered transitions between Mayo endoscopic subscore (MES) 3, 2 and ≤1 (baseline to post-induction).

RESULTS

A 1-compartment population pharmacokinetic model with interindividual and interoccasion variability was found to fit the data best. Covariates influencing exposure were C-reactive protein, albumin, baseline MES, fat-free mass, concomitant corticosteroid use and pancolitis. The cumulative area under the infliximab concentration-time curve until endoscopy (CAUC_endoscopy ) was found to be the best exposure metric for predicting mucosal healing (baseline MES >1 and post-induction MES ≤1). The model predicted that 70% of patients will attain mucosal healing with infliximab administered at days 0, 14 and 42 and a target CAUC_endoscopy of 3752 mg/L*day at day 84.

CONCLUSIONS

TDM-based dose individualisation targeting CAUC_endoscopy has the potential to improve the effectiveness of infliximab during induction therapy.

Advances in Therapeutic Drug Monitoring for Small-Molecule and Biologic Therapies in Inflammatory Bowel Disease

PURPOSE OF REVIEW

Therapeutic drug monitoring (TDM) is increasingly utilized as a strategy to optimize inflammatory bowel disease (IBD) therapeutics. As management paradigms have evolved towards treat-to-target strategies, there has been growing interest in expanding the role of TDM to guide drug optimization for achieving objective endpoints. This review summarizes the evidence for using TDM with biologic and oral small-molecule therapies, evaluates the role of reactive versus proactive TDM in treatment algorithms, and identifies potential future applications for TDM.

RECENT FINDINGS

Achieving therapeutic drug concentrations has been associated with important clinical, endoscopic, and histologic outcomes in IBD. However, the optimal drug concentration varies by therapeutic agent, disease phenotype, inflammatory burden, phase of treatment, and target outcome. Traditionally, TDM has been used reactively to define pharmacokinetic versus mechanistic failures after loss of response to a tumor necrosis factor-α (TNF) antagonist and while observational data suggests a benefit to proactive TDM, this has not been definitively confirmed in prospective randomized controlled trials. The role of TDM in optimizing vedolizumab, ustekinumab, and tofacitinib remains unclear, given differences in pharmacokinetics and immunogenicity compared to TNF antagonists. Measuring drug action at the site of inflamed tissue may provide additional insights into treatment optimization. The use of TDM offers the possibility of a more personalized treatment approach for patients with IBD. High-quality studies are needed to delineate the role of proactive TDM for maintaining remission, for optimizing induction regimens, and for novel agents.

Optimal management of acute severe ulcerative colitis

Acute severe ulcerative colitis is a life-threatening medical emergency, which can be associated with significant morbidity and is preventable through prompt and effective management. Corticosteroids remain the cornerstone of initial therapy, although a third of patients will not respond. Further management hinges on timely decisions with use of rescue therapy with ciclosporin or infliximab, without compromising the health or safety of the patient, or timely surgery. Although such patients need specialist care, it is imperative that emergency care physicians are aware of the important principles of management of this condition to achieve successful outcomes. Risk stratification and the use of predictive models using clinical parameters have reduced the morbidity associated with this condition.We discuss current evidence and present a clinical approach to clinicians involved in the emergency care of patients with acute severe ulcerative colitis in this review.

Contemporary Medical Management of Acute Severe Ulcerative Colitis

Acute severe ulcerative colitis is a medical emergency that requires prompt recognition, evaluation, and intervention. Patients require hospital admission with laboratory, radiographic, and endoscopic evaluation with initiation of corticosteroid treatment. Despite early intervention, many patients require salvage medical therapy, with some progressing to colectomy. Here we review important concepts and recent advances in the evaluation and medical management of adult and pediatric patients with acute severe ulcerative colitis.

Higher Infliximab Trough Levels Are Associated With Better Outcome in Paediatric Patients With Inflammatory Bowel Disease

BACKGROUND

The role of therapeutic drug monitoring for infliximab [IFX] therapy in children with inflammatory bowel disease [IBD] is poorly investigated. We determined if IFX exposure correlates with long-term remission in children.

METHODS

In this retrospective study, all children with Crohn's disease [CD] and ulcerative colitis [UC], receiving maintenance IFX at our centre, were included. Serum trough levels and cumulative drug exposure were correlated with clinical, biological, and endoscopic remission. All children received proactive drug monitoring and dose adaptation aiming to target a therapeutic window of 3-7 µg/mL. All data are presented as median [interquartile range].

RESULTS

A total of 686 serum levels during IFX maintenance in 52 paediatric patients [33 CD and 19 UC] were included (median 9 [4-18] per patient). With a median of 17 [8-36] months under IFX therapy, 39/52 [75%] patients were in clinical remission and 29/40 [73%] patients were in endoscopic remission. Median IFX trough levels were significantly higher when children achieved clinical remission (5.4 [3.8-8.0] µg/mL versus 4.2 [2.6-6.7] µg/mL), biological remission (5.2 [3.7-7.7] µg/mL versus 4.2 [2.6-6.5] µg/mL), combined clinical and biological remission (5.7 [4.0-8.2] µg/mL versus 4.4 [2.7-6.8] µg/mL) and endoscopic remission (6.5 [4.2-9.5] µg/mL versus 3.2 [2.3-5.6] µg/mL) compared with not meeting these criteria [all p ≤ 0.001].

CONCLUSIONS

In this large paediatric cohort, children with clinical and/or endoscopic remission had significantly higher IFX exposure during maintenance therapy. We showed excellent outcome data using serial and systematic measurements of drug levels. This could provide a rationale for the use of proactive drug monitoring in children in order to improve long-term outcomes.

Wide variation in the use and understanding of therapeutic drug monitoring for anti-TNF agents in inflammatory bowel disease: an inexact science?

BACKGROUND

We aimed to understand the way in which therapeutic drug monitoring (TDM) is used, understood and interpreted for anti-TNF agents in IBD.

RESEARCH DESIGN AND METHODS

We designed an 18-question survey that included 5 TDM-based clinical scenarios, for which the 'most appropriate' responses were based on the BRIDGe groups 'Anti-TNF Optimizer'. This resource combines TDM evidence with expert consensus.

RESULTS

We received 110 complete responses: 50 (45%) consultants, 30 (27%) trainees, 25 (23%) IBD nurse specialists and 5 (5%) gastroenterology pharmacists. Over half (61, 55%) only carry out TDM in non-response. The remainder use TDM routinely, including during stable maintenance therapy for patients in remission. Lower therapeutic thresholds used were variable. Most (82, 75%) were unsure whether their laboratory uses a drug-tolerant or drug-sensitive antidrug antibody assay and few (15, 14%) understand the difference. Consultants, high-frequency users (> 3requests/month) and clinicians with larger anti-TNF cohorts (> 100) were significantly more likely to select the 'most appropriate' answer to at least 1 of the 5 TDM-based clinical scenarios.

CONCLUSIONS

There exists marked heterogeneity in the practical use, understanding and interpretation of biologic TDM. Biologic decision-making, informed by TDM, should involve consultation with experienced clinicians who are frequent TDM users, ideally, as part of a multidisciplinary, biologics-focused IBD meeting.

ABBREVIATIONS

TDM: therapeutic drug monitoring; CNS: clinical nurse specialist; ELISA: enzyme-linked immunosorbent assay; RIA: radioimmunoassays; HMSA: homogenous mobility shift assays; BSG: British Society of Gastroenterology.

Severe endoscopic lesions are not associated with more infliximab fecal loss in acute severe ulcerative colitis

BACKGROUND

It has been observed that early infliximab (IFX) fecal excretion in patients with acute severe ulcerative colitis (ASUC) was associated with low treatment response.

AIM

The objective was to assess if severe endoscopic lesions (SEL) were associated with IFX loss in the stool as well as low IFX concentrations in plasma at day 1 and 2 in a cohort of patients admitted for ASUC.

METHODS

Consecutive patients admitted for a steroid-refractory ASUC requiring IFX and who underwent flexible sigmoidoscopy before starting the drug were included in a case-control, prospective, two-center study. Cases were patients with SEL and controls those without SEL. Plasmatic and fecal IFX concentrations were measured at day 1 and 2.

RESULTS

Among the 15 patients analyzed (10 men; median age: 49 years), 6 were cases harboring SEL at baseline. IFX was detected in the stool in 2/6 (33%) of cases and 4/9 (44%) of controls (p = 1) and no difference was observed between the two groups regarding plasmatic concentrations at day 1 or 2 (p = 1).

CONCLUSION

In ASUC, SEL were not associated with more loss of IFX in the stool or lower plasmatic levels. Early IFX pharmacokinetics in this setting does not seem related to endoscopic severity.

Proactive Therapeutic Drug Monitoring of TNF Antagonists in Inflammatory Bowel Disease

BACKGROUND

Proactive therapeutic drug monitoring (TDM) to titrate tumor necrosis factor (TNF) antagonists has emerged recently as a tool to routinely monitor drug concentration to achieve target levels in patients with quiescent inflammatory bowel disease (IBD).

METHODS

The purpose of the present review article was to present available data exploring the concept of proactive TDM.

RESULTS

While several observational studies have identified an association between proactive TDM and better IBD outcomes, 2 randomized controlled studies did not confirm this advantage.

CONCLUSIONS

Based on the evidence to date, proactive TDM cannot be recommended in daily practice. However, analysis is hampered by the low level of evidence for the cutoffs used and the need for point-of-care assays. Regarding economic issues and de-escalating strategies, proactive TDM may have several future indications in IBD. Exploratory studies on proactive TDM with newly available biologic agents in IBD are also awaited.

CRP/Albumin Ratio: An Early Predictor of Steroid Responsiveness in Acute Severe Ulcerative Colitis

INTRODUCTION

Identifying hospitalized patients with acute severe ulcerative colitis (ASUC) who will be refractory to corticosteroid therapy and require rescue therapy remains difficult. Hypoalbuminemia worsens with time during hospitalization and is associated with rapid clearance of and reduced response to infliximab (IFX) rescue. Early use of rescue therapy may therefore be more effective. Simple clinical and laboratory predictors of corticosteroid responsiveness would facilitate earlier use of rescue therapy.

MATERIALS AND METHODS

Retrospective study of a prospectively maintained database of 3600 patients attending a single center was conducted. Patients with histologically confirmed ulcerative colitis admitted with ASUC over a 5-year period from January 2010 to December 2014 were identified. All patients initially received intravenous corticosteroids. Patient demographics were collected; C-reactive protein (CRP) and albumin levels were recorded at baseline and during admission. Receiver operating characteristic statistics were used to determine the optimal stool frequency, CRP, albumin, and CRP/albumin ratio (CAR) to predict steroid response.

RESULTS

A total of 124 ASUC patients were admitted during a 5-year period. Median follow-up was 2.3 years. A total of 62 patients (50%) were steroid responsive, 55 patients (44%) received rescue IFX, 22 patients (18%) required colectomy within 30 days of admission, whereas a further 14 (11%) required colectomy during follow-up. By receiver operating characteristic statistics, day 3 CAR was a more accurate marker of steroid responsiveness than day 3 CRP or day 3 albumin alone [area under curve=0.75 (P<0.001)]. The optimal CAR to predict response to steroids on day 3 was 0.85 (sensitivity 70%, specificity 76%). When combined with D3 stool frequency, specificity improved to 83%. If at day 3, CAR was >0.85 and stool frequency was >3, the relative risk of steroid nonresponse was significantly raised at 3.9 (95% confidence interval, 2.1-7.2).

CONCLUSIONS

Raised D3 CAR is an early predictor of steroid-refractory ASUC. When combined with D3 stool frequency, its predictive ability improves. In patients with predicted steroid nonresponse, early introduction of rescue IFX at this stage may be more effective, before serum albumin falls profoundly.

Accounting for Pharmacokinetic Variability of Certolizumab Pegol in Patients with Crohn's Disease

BACKGROUND

Certolizumab pegol is an effective biologic for patients with Crohn's disease (CD). Individual differences in certolizumab pegol apparent clearance (CL/F) affect exposure and possibly efficacy. A previously developed population pharmacokinetic (PK) model did not account for dynamic changes in clinical parameters during therapy.

OBJECTIVE

The aim of this study was to refine the existing PK model to capture the time-varying influence of covariates.

METHODS

Data collected from 2157 Crohn's disease patients in nine studies were analyzed using nonlinear mixed-effects modeling software (NONMEM). Certolizumab pegol concentration-time data were described by a one-compartment PK model with first-order absorption, and one-compartment disposition with linear, time-dependent elimination using antidrug antibody (ADAb) concentration as a continuous variable.

RESULTS

The final dataset consisted of 12,926 analyzable records. Parameter estimates were absorption rate constant 1.83/day, CL/F 0.527 L/day, and apparent volume of distribution (V/F) 8.33 L. ADAb concentration (2.5-214 units/mL) increased the median CL/F by 142-174%. For a typical patient, body weight (46.8-100.5 kg) increased the median CL/F and V/F from 82 to 120%. Albumin (32-48 g/L) decreased and C-reactive protein (0.5-54.0 mg/L) increased the median CL/F from 123 to 85% and from 83 to 113%, respectively. Between-patient variability of CL/F was 19.6%.

CONCLUSIONS

By incorporating time-varying covariates, this population PK model reduces between-patient variability on CL/F estimates, and the relative influence of ADAb can now be assessed. As Crohn's disease patient covariates are often time-dependent, this model is more reflective of patient drug exposure with sustained treatment.

Prospective Observational Evaluation of Time-Dependency of Adalimumab Immunogenicity and Drug Concentrations: The POETIC Study

OBJECTIVES

Adalimumab is usually self-injected at home, making prospective serial-sampling studies challenging and scarce. This has led to a gap in knowledge about evolution of anti-adalimumab antibodies (AAAs) over time and its correlation with clinical and inflammatory outcomes.

METHODS

A program for home visits by physicians at induction, every 3 months and at event of relapse, was established prospectively for Crohn's disease (CD) patients. At each visit, patients' clinical scores were determined and sera were obtained for C-reactive protein, drug, and AAA levels. This cohort was compared to a parallel prospective cohort of infliximab-treated CD patients. In a subgroup of 29 patients, trough and in-between-trough levels were compared, to elucidate the importance of timing of sampling during the injection cycle.

RESULTS

Ninety-eight CD patients starting adalimumab were prospectively followed (median follow-up 44 weeks) and 621 serum samples were analyzed. Thirty-three patients (32%) developed AAA; 18/33 (55%) of them as early as week 2, and 26/33 (79%) by week 14. Induction period AAAs were strongly associated with primary non-response (odds ratio (OR) = 5.4, 95% confidence interval (CI): 1.6-17.8, p = 0.005). As compared to antibodies-to-infliximab (ATI), AAA formation rate over time was significantly lower (p = 0.01) and AAA were much more specific-85% of AAA events were associated with loss-of-response compared with 58% rate for ATI (p = 0.01). In 29 patients sampled serially during an injection cycle, levels of drug and AAA seemed comparable between four time-points during a single cycle both in patients with or without AAA (n = 8, n = 21, respectively).

CONCLUSIONS

When followed prospectively and serially, AAAs are found to arise earlier than previously appreciated and their impact may be more pronounced for primary rather than secondary, non-response. Drug and AAA levels were similar both at trough and in-between injections, enabling to simplify therapeutic drug monitoring of adalimumab.

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

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