Ustekinumab as Induction and Maintenance Therapy for Crohn's Disease

Ustekinumab: A Review in Moderate to Severe Crohn's Disease

Ustekinumab (Stelara^®) has been recently approved in the EU and the USA as intravenous induction and subcutaneous maintenance therapy for adult patients with moderately to severely active Crohn's disease who have failed or were intolerant to treatment with immunomodulators, corticosteroids or at least one tumour necrosis factor (TNF) antagonist. Ustekinumab, a monoclonal antibody to the shared p40 subunit of the proinflammatory interleukin (IL)-12 and IL-23 cytokines, has a unique mechanism of action distinct from that of TNF antagonists. In pivotal phase III trials, compared with placebo, ustekinumab induction therapy improved clinical response and remission rates in patients who had previously failed or were intolerant to conventional therapies or at least one TNF antagonist. When administered as subcutaneous maintenance therapy, ustekinumab continued to offer benefits over placebo for clinical response and remission in patients who had clinically responded to the induction therapy. Ustekinumab was generally well tolerated as both induction and maintenance therapy; serious infections and malignancies were rare. Thus, ustekinumab presents a promising alternative treatment option in patients with moderately to severely active Crohn's disease who have failed or are intolerant to treatment with conventional therapies or TNF antagonists.

The Future of Janus Kinase Inhibitors in Inflammatory Bowel Disease

Inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, are disabling conditions characterised by chronic, relapsing inflammation of the gastrointestinal tract. Current treatments are not universally effective or, in the case of therapeutic antibodies, are hampered by immune responses. Janus kinase inhibitors are orally delivered small molecules that target cytokine signalling by preventing phosphorylation of Janus kinases associated with the cytokine receptor. Subsequently, phosphorylation of signal transducers and activators of transcription that relay Janus kinase signalling and transcription of cytokines in the nucleus will be diminished. Key cytokines in the pathogenesis of inflammatory bowel diseases are targeted by Janus kinase inhibitors. Several Janus kinase inhibitors are in development for the treatment of inflammatory bowel diseases. Tofacitinib, inhibiting signalling via all Janus kinase family members, was effective in phase 2 and 3 trials in moderate-severe ulcerative colitis. GSK2586184, a Janus kinase 1 selective inhibitor, induced clinical and endoscopic response in ulcerative colitis; however, the study was discontinued at an early stage due to liver toxicity observed in systemic lupus patients receiving the drug. Filgotinib, a Janus kinase 1 selective inhibitor investigated in treatment of Crohn's disease, was superior to placebo. As adverse events associated with the broad immunological effect of these agents have been reported, the future application of these drugs is potentially limited. We will discuss the treatment efficacy of Janus kinase inhibition in inflammatory bowel diseases, how current Janus kinase inhibitors available target immune responses relevant in inflammatory bowel disease, and whether more specific kinase inhibition could be effective.

Etiopathogenesis of inflammatory bowel disease: today and tomorrow

PURPOSE OF REVIEW

Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), represent chronic diseases of unknown cause, and they are regarded as prototypical complex diseases. Despite all the recent advances, a complete appreciation of the pathogenesis of IBD is still limited. In this review, we present recent information contributing to a better understanding of mechanisms underlying IBD.

RECENT FINDINGS

Here, we attempt to highlight novel environmental triggers, data on the gut microbiota, its interaction with the host, and the potential influence of diet and food components. We discuss recent findings on defective signaling pathways and the potential effects on the immune response, and we present new data on epigenetic changes, inflammasome, and damage-associated molecular patterns associated with IBD.

SUMMARY

The continuing identification of several epigenetic, transcriptomic, proteomic, and metabolomic alterations in patients with IBD reflects the complex nature of the disease and suggests the need for innovative approaches such as systems biology for identifying novel relevant targets in IBD.

Frontiers in Drug Research and Development for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is idiopathic, lifelong, immune-mediated diseases, for which curative therapies are not yet available. In the last 15 years, the introduction of monoclonal antibodies targeting tumor necrosis factor-α, a cytokine playing a key role in bowel inflammation, has revolutionized treatment paradigms for IBD. Despite their proven long-term efficacy, however, many patients do not respond or progressively lose response to these drugs. Major advances of knowledge in immunology and pathophysiology of intestinal inflammatory processes have made possible the identification of new molecular targets for drugs, thus opening several new potential therapeutic opportunities for IBD. The abnormal response of intestinal immunity to unknown antigens leads to the activation of T helper lymphocytes and triggers the inflammatory cascade. Sphingosine 1-phosphate receptor agonists negatively modulate the egress of lymphocytes, inducted by antigen-presenting cells, from secondary lymphoid tissues to intestinal wall. Leukocyte adhesion inhibitors (both anti-integrin and anti-Mucosal Vascular Addressin Cell Adhesion Molecule 1) interfere with the tissue homing processes. Activated T helper lymphocytes increase the levels of pro-inflammatory cytokines, such as interleukin 12, 23, and 6, offering several potential pharmacological interventions. The Janus kinases, intracellular enzymes mediating the transduction of several cytokine signals, are other explored targets for treating immune-mediated diseases. Finally, the impact of modulating Smad7 pathway, which is responsible for the down-regulation of the immunosuppressive cytokine transforming growth factor-β signaling, is currently under investigation. The purpose of this review is to discuss the most promising molecules in late-stage clinical development, with a special emphasis on pharmacological properties.

New treatment strategies for ulcerative colitis

INTRODUCTION

Therapeutic strategies in ulcerative colitis are evolving. A personalized and optimal use of available drugs and the integration of new drug classes are the cornerstones underpinning the new treatment paradigms. Areas covered: A structured literature search in Medline and PubMed, Cochrane meta-analyses, and abstracts of international congresses has been performed to review therapeutic approaches to ulcerative colitis. The primary therapeutic objective of therapy is to achieve clinical remission since persistence of active disease, even if mild, leads to a significant reduction in quality of life. Current treatment paradigms of ulcerative colitis are based on the use of 5-aminosalycilates, corticosteroids, thiopurines, TNF-α inhibitors and α4ß7 integrin blockers. The main determinants for drug class selection are disease extension, disease severity, and previous drug history. New drug classes that will likely become available in the foreseeable future include inhibitors of Janus kinases, modulators of sphingosine-1-phosphate receptors, SMAD-7 antisense oligonucleotides, interleukin-12/23 blockers, and fecal microbiota transplantation. Expert commentary: Increasing therapeutic options for ulcerative colitis make predictors of response highly relevant. While these are not available, judicious use of therapies, avoidance of underdosing, or persistent therapy when criteria for drug failure are met are essential.

Pharmacokinetic drug evaluation of budesonide in the treatment of Crohn's disease

INTRODUCTION

Crohn's disease (CD) is a chronic inflammatory disorder that commonly affects the terminal ileum and proximal colon. Although systemic corticosteroids such as prednisone and methylprednisolone are widely used for treatment of CD, these agents have a high incidence of adverse drug reactions due to off-target effects. Budesonide is a locally acting corticosteroid with enhanced formulation properties that offer a superior therapeutic index in comparison to conventional members of the class. Areas covered: This review focuses on budesonide for the treatment of CD. The pharmacological and pharmacokinetics of the drug are summarized, along with clinical efficacy and safety data. We also indicate the role of budesonide in therapeutic algorithms. Expert opinion: Budesonide has an important role as an induction therapy in patients with mild to moderately active CD of the ileum and proximal colon. The most distinctive advantage of budesonide over conventional corticosteroids is a substantially reduced risk of corticosteroid-related side effects.

Management of Crohn's disease in Taiwan: consensus guideline of the Taiwan Society of Inflammatory Bowel Disease

Crohn's disease (CD) is a chronic relapsing and remitting inflammatory disease of the gastrointestinal tract. CD is rare in Taiwan and other Asian countries, but its prevalence and incidence have been steadily increasing. A steering committee was established by the Taiwan Society of Inflammatory Bowel Disease to formulate statements on the diagnosis and management of CD taking into account currently available evidence and the expert opinion of the committee. Thorough clinical, endoscopic, and histological assessments are required for accurate diagnosis of CD. Computed tomography and magnetic resonance imaging are complementary to endoscopic evaluation for disease staging and detecting complications. The goals of CD management are to induce and maintain remission, reduce the risk of complications, and improve quality of life. Corticosteroids are the mainstay for inducing re-mission. Immunomodulating and biologic therapies should be used to maintain remission. Patients should be evaluated for hepatitis B virus and tuberculosis infection prior to treatment and receive regular surveillance for cancer. These consensus statements are based on current local evidence with consideration of factors, and could be serve as concise and practical guidelines for supporting clinicians in the management of patients with CD in Taiwan.

Management of Inflammatory Bowel Disease in the Elderly Patient: Challenges and Opportunities

The population of older patients with inflammatory bowel disease (IBD) continues to grow, partly reflecting the aging global population in general. The debilitating effects of IBD compound age-related decrements in health and functional capacity, and make the medical management of older patients with Crohn's disease and ulcerative colitis distinctly challenging to clinicians. Here, we review the recent literature describing the pharmacologic management of IBD in this population, with focus on the safety, tolerability, and efficacy of common treatment options, such as steroids, immunomodulators, tumor necrosis factor-α antagonists, and integrin antagonists; surgical interventions in older patients are also discussed. Few studies have systematically and prospectively evaluated the clinical challenges in the medical management of IBD in this patient population, leaving a limited evidence base to which clinicians can turn to for guidance. Treatment patterns may thus be suboptimal. For example, prolonged steroid use in the elderly was found to be common, causing significant morbidity from side effects in a particularly vulnerable population. Finally, within the context of a limited evidence base, we discuss common treatment scenarios to define the parameters within which physicians can individualize care for older patients with IBD. Overall, older patients with IBD are at higher risk of adverse events and less treatment responsiveness compared with younger patients, underscoring the need for future studies to fully characterize appropriate treatment courses for this population.

Developments in therapy with monoclonal antibodies and related proteins

Monoclonal antibody therapeutics have been approved for over 30 targets and diseases, most commonly cancer. Antibodies have become the new backbone of the pharmaceutical industry, which previously relied on small molecules. Compared with small molecules, monoclonal antibodies (mAbs) have exquisite target selectivity and hence less toxicity as a result of binding other targets. The clinical value of both mAbs and ligand traps has been proven. New applications of mAbs are being tested and mAbs have now been designed to target two (bi-specific, eg TNF-α and IL-17) or more targets simultaneously, augmenting their therapeutic potential. Because of space limitations and the wide ranging scope of this review there are regrettably, but inevitably, omissions and missing citations. We have chosen to highlight the first successes in inflammatory diseases and cancer, but a broader overview of approved mAbs and related molecules can be found in Table 1.

[Second Korean Guidelines for the Management of Crohn's Disease]

Crohn's disease (CD) is a chronic, progressive, and disabling inflammatory bowel disease (IBD) with an uncertain etiopathogenesis. CD can involve any site of the gastrointestinal tract from the mouth to the anus, and is associated with serious complications, such as bowel strictures, perforations, and fistula formation. The incidence and prevalence rates of CD in Korea are still lower compared with those in Western countries, but they have been rapidly increasing during the recent decades. Although there are no definitive curative modalities for CD, various medical and surgical therapies have been applied for the treatment of this disease. Concerning CD management, there have been substantial discrepancies among clinicians according to their personal experience and preference. To suggest recommendable approaches to the diverse problems of CD and to minimize the variations in treatment among physicians, guidelines for the management of CD were first published in 2012 by the IBD Study Group of the Korean Association for the Study of the Intestinal Diseases. These are the revised guidelines based on updated evidence, accumulated since 2012. These guidelines were developed by using mainly adaptation methods, and encompass induction and maintenance treatment of CD, treatment based on disease location, treatment of CD complications, including stricture and fistula, surgical treatment, and prevention of postoperative recurrence. These are the second Korean guidelines for the management of CD and will be continuously revised as new evidence is collected.

Incidence, Prevention and Management of Anti-Drug Antibodies Against Therapeutic Antibodies in Inflammatory Bowel Disease: A Practical Overview

The introduction of biologic therapy has revolutionized the treatment of inflammatory bowel disease (IBD). However, like all therapeutic proteins, monoclonal antibodies have immunogenic potential which is influenced by multiple drug- and patient-related factors. The reported incidence of anti-drug antibodies (ADAs) towards biologic drugs in IBD varies greatly in the literature and depends not only on differences in sensitization but also on the assay methodology and the timepoint of measurement. Sensitization with formation of ADAs is associated with an increased risk of infusion reactions, accelerated drug clearance, and a loss of response (LOR) to drug. Recently, a greater understanding of the pharmacokinetics of therapeutic antibodies has led to the development of new strategies to reduce immunogenicity and more efficient use of these drugs. These preventive strategies include regular scheduled dosing with maintenance of stable therapeutic trough drug concentrations, and co-administration of an immunosuppressive. Sub-therapeutic drug concentrations with low levels of ADAs can generally be overcome with dose escalation, whereas the presence of high concentrations of ADAs requires a switch to another therapeutic agent.

Combination therapy for inflammatory bowel disease

Biologic therapies such as infliximab and adalimumab have become mainstays of treatment for inflammatory bowel disease. Early studies suggested that combination therapy (CT) with infliximab and an immunomodulator drug such as azathioprine may help optimize biologic pharmacokinetics, minimize immunogenicity, and improve outcomes. The landmark SONIC trial in Crohn's disease and the UC SUCCESS trial in ulcerative colitis demonstrated CT with infliximab and azathioprine to be superior to monotherapy with either agent alone at inducing clinical remission in treatment naïve patients with moderate to severe disease. However, many unanswered questions linger. The role of CT in non-naive patients as well as the optimal duration of CT remains unknown. The effectiveness of CT with alternate biologics and/or alternate immunomodulators is not as clear, and it is unknown whether SONIC's conclusions can be extrapolated beyond infliximab and azathioprine. Also looming are the risks of CT including opportunistic infection and malignancy; specifically, lymphoma. This review lays out the evidence as it pertains to the risks and benefits of CT as well as the areas that require further research. With this information in hand, the practitioner may develop a treatment strategy that best suits each individual patient.

Current and emerging therapeutic targets for IBD

Various therapeutic advances have led to a paradigm shift in the clinical management of patients with IBD. The introduction of immunosuppressive (such as azathioprine) and biologic agents (such as TNF blockers) has markedly reduced the need to use corticosteroids for therapy. Furthermore, the α4β7 integrin blocker vedolizumab has been introduced for clinical IBD therapy. Moreover, various new inhibitors of cytokines (for example, IL-6-IL-6R and IL-12-IL-23 blockers or apremilast), modulators of cytokine signalling events (for example, JAK inhibitors or SMAD7 blocker), inhibitors of transcription factors (for example, GATA3 or RORγt) and new anti-adhesion and anti-T-cell-activation and migration strategies (for example, β7 integrin, sphingosine 1-phosphate receptors and MAdCAM1 inhibitors, regulatory T-cell therapy and stem cells) are currently being evaluated in controlled clinical trials. This Review aims to provide a comprehensive overview about current and future therapeutic approaches for IBD therapy. Furthermore, potential mechanisms of action of these therapeutic approaches and their implications for clinical therapy in IBD are discussed.

Clinical, endoscopic and radiographic outcomes with ustekinumab in medically-refractory Crohn's disease: real world experience from a multicentre cohort

BACKGROUND

Ustekinumab is a monoclonal antibody targeting interleukins-12 and -23, with efficacy in Crohn's disease (CD) demonstrated in clinical trials.

AIM

To assess the real-world clinical, endoscopic and radiographic response and remission outcomes achieved with ustekinumab in medically-refractory CD.

METHODS

A retrospective multicentre cohort study was performed on CD patients receiving ustekinumab between 2011 and 2016. The primary outcome was achievement of clinical and objective steroid-free response and remission at 3, 6 and 12 months. Clinical response and remission were defined by reduction in Harvey Bradshaw Index (HBI) of ≥3 points and an HBI ≤4 points respectively. Objective response was defined by improvement in endoscopic or radiographic CD, as assessed by ileocolonoscopy, contrast-enhanced ultrasound or CT/MR enterography. Objective remission was defined by endoscopic mucosal healing or complete resolution of inflammatory parameters on radiographic assessment.

RESULTS

A total of 167 CD patients were treated with ustekinumab. 95.2% (159/167) previously failed anti-TNF therapy. Median follow-up was 45.6 weeks (IQR: 24.4-88.9). At 3 months, clinical response was achieved in 38.9% (65/167) and remission in 15.0% (25/167) of patients. At 6 months, clinical response was achieved in 60.3% (91/151) and remission in 25.2% (38/151) of patients. At 12 months, clinical response was achieved in 59.5% (66/111) and remission in 27.9% (31/111) of patients. Endoscopic or radiographic response was demonstrated in 54.5% (67/123) at 6 months and 55.8% (48/86) of patients at 12 months.

CONCLUSIONS

Ustekinumab is an effective therapeutic option for inducing and maintaining clinical, endoscopic and radiographic response in patients with Crohn's disease failing anti-TNF therapy.

Long-term Maintenance of Clinical, Endoscopic, and Radiographic Response to Ustekinumab in Moderate-to-Severe Crohn's Disease: Real-world Experience from a Multicenter Cohort Study

BACKGROUND

Ustekinumab is a monoclonal antibody targeting interleukins 12 and 23. While effective in clinical trials for Crohn's disease (CD), long-term maintenance of response in the real-world setting is unclear. We aim to assess the efficacy of ustekinumab for maintaining clinical, endoscopic, and radiographic response in CD.

METHODS

A retrospective multicenter cohort study was performed on patients with CD achieving steroid-free clinical response to ustekinumab induction, and advanced onto a regularly scheduled maintenance ustekinumab regimen between 2011 and 2016. The primary outcome was loss of response, defined by an increase in Harvey Bradshaw Index of >3 points from baseline requiring ustekinumab dose escalation, reinduction, rescue corticosteroids, immunomodulators, surgery, or ustekinumab discontinuation. Multivariate Cox proportional hazards regression was used to identify clinical factors associated with loss of response.

RESULTS

One hundred four patients with CD achieving steroid-free response with ustekinumab induction were included; 92.3% (96/104) had previously failed antitumor necrosis factor therapy. Median follow-up was 57.2 weeks (interquartile range (IQR): 36.7-103.4). Cumulative probability of maintained response at 52 weeks was 71.8%. Sixty-seven patients (64.4%) maintained endoscopic or radiographic response. Thirty-five patients (33.7%) lost response at a median time of 47.4 weeks (IQR: 35.3-68.4). Dose escalation was required in 17 patients (16.3%); response was recaptured in 9/17 (52.9%). Nine patients (8.7%) required surgery. In Cox multivariate regression, concurrent immunomodulation was associated with reduced risk of loss of response (hazards ratio 0.39 (95% CI, 0.17-0.92)).

CONCLUSIONS

Subcutaneous ustekinumab is an effective treatment option for maintaining long-term clinical, endoscopic, and radiographic response in patients with moderate-to-severe CD failing antitumor necrosis factor therapy.

Oncostatin M drives intestinal inflammation and predicts response to tumor necrosis factor-neutralizing therapy in patients with inflammatory bowel disease

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are complex chronic inflammatory conditions of the gastrointestinal tract that are driven by perturbed cytokine pathways. Anti-tumor necrosis factor-α (TNF) antibodies are mainstay therapies for IBD. However, up to 40% of patients are nonresponsive to anti-TNF agents, which makes the identification of alternative therapeutic targets a priority. Here we show that, relative to healthy controls, inflamed intestinal tissues from patients with IBD express high amounts of the cytokine oncostatin M (OSM) and its receptor (OSMR), which correlate closely with histopathological disease severity. The OSMR is expressed in nonhematopoietic, nonepithelial intestinal stromal cells, which respond to OSM by producing various proinflammatory molecules, including interleukin (IL)-6, the leukocyte adhesion factor ICAM1, and chemokines that attract neutrophils, monocytes, and T cells. In an animal model of anti-TNF-resistant intestinal inflammation, genetic deletion or pharmacological blockade of OSM significantly attenuates colitis. Furthermore, according to an analysis of more than 200 patients with IBD, including two cohorts from phase 3 clinical trials of infliximab and golimumab, high pretreatment expression of OSM is strongly associated with failure of anti-TNF therapy. OSM is thus a potential biomarker and therapeutic target for IBD, and has particular relevance for anti-TNF-resistant patients.

Induction therapy with the selective interleukin-23 inhibitor risankizumab in patients with moderate-to-severe Crohn's disease: a randomised, double-blind, placebo-controlled phase 2 study

BACKGROUND

The interleukin-23 pathway is implicated genetically and biologically in the pathogenesis of Crohn's disease. We aimed to assess the efficacy and safety of risankizumab (BI 655066, Boehringer Ingelheim, Ingelheim, Germany), a humanised monoclonal antibody targeting the p19 subunit of interleukin-23, in patients with moderately-to-severely active Crohn's disease.

METHODS

In this randomised, double-blind, placebo-controlled phase 2 study, we enrolled patients at 36 referral sites in North America, Europe, and southeast Asia. Eligible patients were aged 18-75 years, with a diagnosis of Crohn's disease for at least 3 months, assessed as moderate-to-severe Crohn's disease at screening, defined as a Crohn's Disease Activity Index (CDAI) of 220-450, with mucosal ulcers in the ileum or colon, or both, and a Crohn's Disease Endoscopic Index of Severity (CDEIS) of at least 7 (≥4 for patients with isolated ileitis) on ileocolonoscopy scored by a masked central reader. Patients were randomised 1:1:1 using an interactive response system to a double-blind investigational product, and stratified by previous exposure to TNF antagonists (yes vs no). Patients received intravenous 200 mg risankizumab, 600 mg risankizumab, or placebo, at weeks 0, 4, and 8. The primary outcome was clinical remission (CDAI <150) at week 12 (intention-to-treat population). Safety was assessed in patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT02031276.

FINDINGS

Between March, 2014, and September, 2015, 213 patients were screened, and 121 patients randomised. At baseline, 113 patients (93%) had been previously treated with at least one tumour necrosis factor (TNF) antagonist (which had failed in 96 [79%]). At week 12, 25 (31%) of 82 risankizumab patients (pooled 41 patients in 200 mg and 41 patients in 600 mg arms) had clinical remission versus six (15%) of 39 placebo patients (difference vs placebo 15·0%, 95% CI 0·1 to 30·1; p=0·0489). Ten (24%) of 41 patients who received 200 mg risankizumab had clinical remission (9·0%, -8·3 to 26·2; p=0·31) and 15 (37%) of 41 who received the 600 mg dose (20·9%, 2·6 to 39·2; p=0·0252). 95 (79%) patients had adverse events (32 in the placebo group, 32 randomised to 200 mg risankizumab, 31 randomised to 600 mg risankizumab); 18 had severe adverse events (nine, six, three); 12 discontinued (six, five, one); 24 had serious adverse events (12, nine, three). The most common adverse event was nausea and most common serious adverse event was worsening of underlying Crohn's disease. No deaths occurred.

INTERPRETATION

In this short-term study, risankizumab was more effective than placebo for inducing clinical remission in patients with active Crohn's disease. Therefore, selective blockade of interleukin-23 via inhibition of p19 might be a viable therapeutic approach in Crohn's disease.

FUNDING

Boehringer Ingelheim.

Uncovering Pathogenic Mechanisms of Inflammatory Bowel Disease Using Mouse Models of Crohn's Disease-Like Ileitis: What is the Right Model?

Crohn's disease and ulcerative colitis, together known as inflammatory bowel disease, are debilitating chronic disorders of unknown cause and cure. Our evolving understanding of these pathologies is enhanced greatly by the use of animal models of intestinal inflammation that allow in vivo mechanistic studies, preclinical evaluation of new therapies, and investigation into the causative factors that underlie disease pathogenesis. Several animal models, most commonly generated in mice, exist for the study of colitis. The appropriateness of their use often can be determined by their mode of generation (ie, chemical induction, T-cell transfer, targeted genetic manipulation, spontaneously occurring, and so forth), the type of investigation (mechanistic studies, pathogenic experiments, preclinical evaluations, and so forth), and the type of inflammation that occurs in the model (acute vs chronic colitis, tissue injury/repair, and so forth). Although most murine models of inflammatory bowel disease develop inflammation in the colon, Crohn's disease most commonly occurs in the terminal ileum, where a very limited number of mouse models manifest disease. This review discusses appropriate experimental applications for different mouse models of colitis, and highlights the particular utility of 2 highly relevant models of Crohn's-like ileitis-the spontaneous SAMP1/YitFc inbred mouse strain and the genetically engineered Tnf^{ΔAU-rich element/+} mouse model of tumor necrosis factor overexpression, both of which bear strong resemblance to the human condition. Similar to patients with Crohn's disease, SAMP1/YitFc ileitis develops spontaneously, without chemical, genetic, or immunologic manipulation, making this model particularly relevant for studies aimed at identifying the primary defect underlying the occurrence of Crohn's ileitis, as well as preclinical testing of novel treatment modalities.

Pathogenesis of Inflammatory Bowel Disease and Recent Advances in Biologic Therapies

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory disorder with an unknown etiology. IBD is composed of two different disease entities: Crohn's disease (CD) and ulcerative colitis (UC). IBD has been thought to be idiopathic but has two main attributable causes that include genetic and environmental factors. The gastrointestinal tract in which this disease occurs is central to the immune system, and the innate and the adaptive immune systems are balanced in complex interactions with intestinal microbes under homeostatic conditions. However, in IBD, this homeostasis is disrupted and uncontrolled intestinal inflammation is perpetuated. Recently, the pathogenesis of IBD has become better understood owing to advances in genetic and immunologic technology. Moreover, new therapeutic strategies are now being implemented that accurately target the pathogenesis of IBD. Beyond conventional immunesuppressive therapy, the development of biological agents that target specific disease mechanisms has resulted in more frequent and deeper remission in IBD patients, with mucosal healing as a treatment goal of therapy. Future novel biologics should overcome the limitations of current therapies and ensure that individual patients can be treated with optimal drugs that are safe and precisely target IBD.

Genetics of inflammatory bowel disease: beyond NOD2

The study of the genetic underpinnings of inflammatory bowel disease has made great progress since the identification of NOD2 as a major susceptibility gene. Novel genotyping and sequencing technologies have led to the discovery of 242 common susceptibility loci, 45 of which have been fine-mapped to statistically conclusive causal variants; 50 genes associated with very-early-onset inflammatory disease have been identified. The evolving genetic architecture of inflammatory bowel disease has deepened our understanding of its pathogenesis through identification of major disease associated pathways-knowledge that has the potential to indicate novel drug targets or markers for personalised medicine. However, many causal variants have yet to be identified, and a large proportion of missing heritability still needs to be accounted for. In addition, the medical and scientific communities are probably not yet fully harnessing the power of these genetic discoveries.

Crohn's disease for the general physician: management

Crohn's disease presents to general physicians in a variety of ways. The previous article outlined clinical features and initial investigations, and this article covers management of Crohn's disease, including monitoring and drug toxicity.

Lessons Learned From Trials Targeting Cytokine Pathways in Patients With Inflammatory Bowel Diseases

Insights into the pathogenesis of inflammatory bowel diseases (IBDs) have provided important information for the development of therapeutics. Levels of interleukin 23 (IL23) and T-helper (Th) 17 cell pathway molecules are increased in inflamed intestinal tissues of patients with IBD. Loss-of-function variants of the IL23-receptor gene (IL23R) protect against IBD, and, in animals, blocking IL23 reduces the severity of colitis. These findings indicated that the IL23 and Th17 cell pathways might be promising targets for the treatment of IBD. Clinical trials have investigated the effects of agents designed to target distinct levels of the IL23 and Th17 cell pathways, and the results are providing insights into IBD pathogenesis and additional strategies for modulating these pathways. Strategies to reduce levels of proinflammatory cytokines more broadly and increase anti-inflammatory mechanisms also are emerging for the treatment of IBD. The results from trials targeting these immune system pathways have provided important lessons for future trials. Findings indicate the importance of improving approaches to integrate patient features and biomarkers of response with selection of therapeutics.

Second Korean guidelines for the management of Crohn's disease

Crohn's disease (CD) is a chronic, progressive, and disabling inflammatory bowel disease (IBD) with an uncertain etiopathogenesis. CD can involve any site of the gastrointestinal tract from the mouth to the anus, and is associated with serious complications, such as bowel strictures, perforations, and fistula formation. The incidence and prevalence rates of CD in Korea are still lower compared with those in Western countries, but they have been rapidly increasing during the recent decades. Although there are no definitive curative modalities for CD, various medical and surgical therapies have been applied for the treatment of this disease. Concerning CD management, there have been substantial discrepancies among clinicians according to their personal experience and preference. To suggest recommendable approaches to the diverse problems of CD and to minimize the variations in treatment among physicians, guidelines for the management of CD were first published in 2012 by the IBD Study Group of the Korean Association for the Study of Intestinal Diseases. These are the revised guidelines based on updated evidence, accumulated since 2012. These guidelines were developed by using mainly adaptation methods, and encompass induction and maintenance treatment of CD, treatment based on disease location, treatment of CD complications, including stricture and fistula, surgical treatment, and prevention of postoperative recurrence. These are the second Korean guidelines for the management of CD and will be continuously revised as new evidence is collected.

Pneumocystis jirovecii Pneumonia in Pediatric Inflammatory Bowel Disease: A Case Report and Literature Review

Immunosuppressive therapy is a known risk factor for opportunistic infections. We report the first case of severe Pneumocystis jirovecii infection requiring intensive care in a pediatric patient with inflammatory bowel disease (IBD). The literature was reviewed and there were 92 reported cases of Pneumocystis pneumonia (PCP) in patients with IBD. Most sources were case reports and there was likely reporting bias toward patients receiving immunomodulators, anti-tumor necrosis factor (anti-TNF) therapy, and those who died. Overall, 56% of patients were males and 58% had Crohn's disease. The median age was 45 years (interquartile range 30-68, range 8-78) and 86% of patients were lymphopenic. The case-fatality rate was 23%. Corticosteroids were used as IBD treatment in 88% of patients who subsequently developed PCP, 42% received thiopurines, 44% used anti-TNF therapy, and 15% received either cyclosporine or tacrolimus. Rates of mono, dual, triple, and quadruple immunosuppression therapy were 35, 35, 29, and 2%, respectively. This report highlights the importance of considering PCP in immunosuppressed lymphopenic pediatric IBD patients who present with unusual symptoms. Moreover, it should give gastroenterologists the impetus to limit immunosuppressive therapy to its minimal effective dose and consider options such as exclusive enteral nutrition wherever possible. Although there is no place for global PCP prophylaxis in IBD given the low incidence, in an era when there is increasing use of biologic agents with combination immunosuppressive therapy, the risk-benefit profile of PCP chemoprophylaxis should be revisited in selected cohorts such as patients on triple immunosuppression with corticosteroids, thiopurines, and a biological agent or calcineurin inhibitor, especially in lymphopenic individuals.

Anti-IL-12/23p40 antibodies for induction of remission in Crohn's disease

BACKGROUND

Ustekinumab (CNTO 1275) and briakinumab (ABT-874) are monoclonal antibodies that target the standard p40 subunit of the cytokines interleukin-12 and interleukin-23 (IL-12/23p40), which are involved in the pathogenesis of Crohn's disease.

OBJECTIVES

The objectives of this review were to assess the efficacy and safety of anti-IL-12/23p40 antibodies for induction of remission in Crohn's disease.

SEARCH METHODS

We searched the following databases from inception to 12 September 2016: PubMed, MEDLINE, EMBASE, and the Cochrane Library (CENTRAL). References and conference abstracts were searched to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs) trials in which monoclonal antibodies against IL-12/23p40 were compared to placebo or another active comparator in patients with active Crohn's disease were included.  DATA COLLECTION AND ANALYSIS: Two authors independently screened  studies for inclusion and extracted data. Methodological quality was assessed using the Cochrane risk of bias tool. The primary outcome was failure to induce clinical remission, defined as a Crohn's disease activity index (CDAI) of < 150 points. Secondary outcomes included failure to induce clinical improvement, adverse events, serious adverse events, and withdrawals due to adverse events. Clinical improvement was defined as decreases of > 70 or > 100 points in the CDAI from baseline. We calculated the risk ratio (RR) and 95% confidence intervals (95% CI) for each outcome. Data were analyzed on an intention-to-treat basis. The overall quality of the evidence supporting the outcomes was evaluated using the GRADE criteria.

MAIN RESULTS

Six RCTs (n = 2324 patients) met the inclusion criteria. A low risk of bias was assigned to all studies. The two briakinumab trials were not pooled due to differences in doses and time points for analysis. In both studies there was no statistically significant difference in remission rates. One study (n = 79) compared doses of 1 mg/kg and 3 mg/kg to placebo. In the briakinumab group 70% (44/63) of patients failed to enter clinical remission at 6 or 9 weeks compared to 81% (13/16) of placebo patients (RR 0.86, 95% CI 0.65 to 1.14). Subgroup analysis revealed no significant differences by dose. The other briakinumab study (n = 230) compared intravenous doses of 200 mg, 400 mg and 700 mg with placebo. Eighty-four per cent (154/184) of briakinumab patients failed to enter clinical remission at six weeks compared to 91% (42/46) of placebo patients (RR 0.92, 95% CI 0.83 to 1.03). Subgroup analysis revealed no significant differences by dose. GRADE analyses of the briakinumab studies rated the overall quality of the evidence for the outcome clinical remission as low. Based on the results of these two studies the manufacturers of briakinumab stopped production of this medication. The ustekinumab studies were pooled despite differences in intravenous doses (i.e. 1mg/kg, 3 mg/kg, 4.5 mg/kg, and 6 mg/kg), however the subcutaneous dose group was not included in the analysis, as it was unclear if subcutaneous was equivalent to intravenous dosing. There was a statistically significant difference in remission rates. At week six, 84% (764/914) of ustekinumab patients failed to enter remission compared to 90% (367/406) of placebo patients (RR 0.92, 95% CI 0.88 to 0.96; 3 studies; high-quality evidence). Subgroup analysis showed a statistically significant difference for the 6.0 mg/kg dose group (moderate-quality evidence). There were statistically significant differences in clinical improvement between ustekinumab and placebo-treated patients. In the ustekinumab group, 55% (502/914) of patients failed to improve clinically (i.e. 70-point decline in CDAI score), compared to 71% (287/406) of placebo patients (RR 0.78, 95% CI 0.71 to 0.85; 3 studies). Subgroup analysis revealed significant differences compared to placebo for the 1 mg/kg, 4.5 mg/kg and 6 mg/kg dosage subgroups. Similarly for a 100-point decline in CDAI, 64% (588/914) of patients in the ustekinumab group failed to improve clinically compared to 78% (318/406) of placebo patients (RR 0.82, 95% CI 0.77 to 0.88; 3 studies; high-quality evidence). Subgroup analysis showed a significant difference compared to placebo for the 4.5 mg/kg and 6.0 mg/kg (high-quality evidence) dose groups. There were no statistically significant differences in the incidence of adverse events, serious adverse events or withdrawal due to adverse events. Sixty-two per cent (860/1386) of ustekinumab patients developed at least one adverse event compared to 64% (407/637) of placebo patients (RR 0.97, 95% CI 0.90 to 1.04; 4 studies; high-quality evidence). Five per cent (75/1386) of ustekinumab patients had a serious adverse event compared to 6% (41/637) of placebo patients (RR 0.83, 95% CI 0.58 to 1.20; 4 studies; moderate-quality evidence). The most common adverse events in briakinumab patients were injection site reactions and infections. Infections were the most common adverse event in ustekinumab patients. Worsening of Crohn's disease and serious infections were the most common serious adverse events.

AUTHORS' CONCLUSIONS

High quality evidence suggests that ustekinumab is effective for induction of clinical remission and clinical improvement in patients with moderate to severe Crohn's disease. Moderate to high quality evidence suggests that the optimal dosage of ustekinumab is 6 mg/kg. Briakinumab and ustekinumab appear to be safe. Moderate quality evidence suggests no increased risk of serious adverse events. Future studies are required to determine the long-term efficacy and safety of ustekinumab in patients with moderate to severe Crohn's disease.

Ustekinumab in treatment of Crohn's disease: design, development, and potential place in therapy

Crohn’s disease is characterized by a dysregulation of both innate and adaptive immunity responses. Interleukin-12/23 (IL-12/23) pathway has been found to be a major driver of inflammation in adaptive immune responses. Ustekinumab is a fully human immunoglobulin G1 kappa monoclonal antibody that blocks the p40 subunit of IL-12 and IL-23 and prevents their interaction with their cell surface receptor and further cytokine activation. It is currently approved in the management of plaque psoriasis and psoriatic arthritis. Very promising data have emerged through phase II and phase III trials (UNITI-1, UNITI-2, and IM-UNITI) for both induction and maintenance of clinical response and remission in moderate-to-severe Crohn’s disease, resulting in approval by the Food and Drug Administration for this condition. This article reviews the immunology of the IL-12/23 pathway, available data regarding the initial designing of ustekinumab, drug development through clinical trials including pharmacokinetics, efficacy, and safety, and its potential place in the treatment of Crohn’s disease.