Anti-interleukin-5 antibody treatment (mepolizumab) in active eosinophilic oesophagitis: a randomised, placebo-controlled, double-blind trial

Eosinophilic esophagitis: short and long-term considerations

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) is a relatively new disease but its understanding is evolving over a period of time. This review highlights recent advances in the understanding of pathophysiology, diagnostic modalities, short and long-term goals of therapy and novel therapeutic agents.

RECENT FINDINGS

The prevalence of EoE is increasing. Upper endoscopy and biopsy remains the gold standard for diagnosing EoE but less invasive and more cost-effective testing has been under investigation. Scoring systems to assess symptoms, histology and endoscopic findings can distinguish between active and inactive disease. Step up therapy with 2-4-6 food elimination can result in early identification of triggering foods and reduce frequency of endoscopies. The term proton pump inhibitor (PPI) responsive eosinophilia should be avoided and PPI should be considered a therapeutic modality. Oral viscous budesonide has been more effective than fluticasone in achieving remission. Adrenal suppression should be looked for patients on swallowed steroids. IL-13 antagonists can be a promising therapy for EoE and dilation is a safe and effective treatment modality in patients with EoE but as is expected, does not decrease inflammation.

SUMMARY

EoE has been increasingly recognized as a cause of food impactions and dysphagia. Less invasive methods for diagnosis and to monitor treatment response have been studied but need validation in children. Short-term treatment goals include symptomatic and histological improvement, with prevention of fibrostenotic disease the primary long-term goal. Elemental diet and empiric elimination diet appear to be successful in inducing remission. PPI and swallowed steroids cause symptomatic improvement and histological remission but relapse is common after discontinuation of therapy.

Eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an atopic condition of the esophagus that has become increasingly recognized over the last 15 years. Diagnosis of the disorder is dependent on the patient’s clinical manifestations, and must be confirmed by histologic findings on esophageal mucosal biopsies. Patients with EoE should be referred to an allergist for optimal management, which may include dietary modifications and pharmacologic agents such as corticosteroids, and for the diagnosis and management of comorbid atopic conditions. Mechanical dilation of the esophagus may also be necessary. The epidemiology, pathophysiology, diagnosis, treatment, and prognosis of EoE are discussed in this review.

Eosinophilic Esophagitis and the Eosinophilic Gastrointestinal Diseases: Approach to Diagnosis and Management

The eosinophilic gastrointestinal diseases (EGIDs) represent disorders of the gastrointestinal (GI) tract that result from the local infiltration and aberrant activity of eosinophils and other immune cells. Eosinophilic esophagitis (EoE) is the most well-characterized EGID and is defined by the presence of intraepithelial eosinophils in the esophagus (≥15 eosinophils per high-powered field) and clinical symptoms associated with esophageal dysfunction. The other EGIDs are rare and lack strong data regarding pathogenesis and management. The incidence and prevalence of EoE are increasing, and EoE is now a major cause of upper GI morbidity. Management is multidisciplinary, with collaboration between gastroenterologists, allergists, pathologists, and dieticians, and is aimed at amelioration of symptoms and prevention of long-term complications such as esophageal stricture. Treatment options for EoE include proton pump inhibitors, swallowed topical corticosteroids, and elimination diets. Esophageal dilation is used when esophageal strictures or fibrostenotic changes are present. Additional therapies targeting eosinophils and other mediators of Th2 inflammation are under development and are promising. Treatment options for other EGIDs typically involve corticosteroids or dietary elimination.

Efficacy of Pharmacologic Therapy for Eosinophilic Esophagitis: A Systematic Review and Network Meta-Analysis

GOALS

In order to provide a comparative evaluation of available pharmacologic treatments for eosinophilic esophagitis (EoE), we conducted a network meta-analysis.

BACKGROUND

A variety of pharmacologic treatments for EoE have been reported, however there exists a paucity of direct comparisons.

STUDY

We searched randomized controlled trials using MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials database through December 2014. Studies were analyzed using a random-effects network meta-analysis to identify the most effective therapy. Subgroup analysis was performed among studies that excluded gastroesophageal reflux disease or proton-pump inhibitor responsive esophageal eosinophilia, and also among pediatric and adult populations. The ranking probability for the efficacy of each treatment was analyzed. Consistency of the included randomized controlled trials was checked by applying inconsistency and node-splitting models.

RESULTS

Eleven studies of a total of 456 patients were identified. Six pharmacologic treatments (budesonide suspension and viscous, fluticasone, prednisone, esomeprazole, and mepolizumab) and placebo were included in our analysis. Meta-analysis showed superiority of budesonide viscous, budesonide suspension, and fluticasone over placebo. Network meta-analysis demonstrated the rank order of efficacy as budesonide viscous, esomeprazole, prednisone, budesonide suspension, fluticasone, mepolizumab, and placebo. The results were consistent from the inconsistency model analysis and node-splitting analysis. Subgroup analysis demonstrated prednisone, budesonide suspension, and esomeprazole were the most effective when network meta-analyses were performed among studies that excluded gastroesophageal reflux disease or proton-pump inhibitor responsive esophageal eosinophilia, and among pediatric and adult populations, respectively.

CONCLUSIONS

On the basis of this network meta-analysis, viscous budesonide was shown to be the most effective pharmacologic therapy for EoE among the reported pharmacologic treatments.

Minimally invasive biomarker studies in eosinophilic esophagitis: A systematic review

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic, inflammatory disease of the esophagus that currently requires repeated endoscopic biopsies for diagnosis and monitoring because no reliable noninvasive markers have been identified.

OBJECTIVE

To identify promising minimally invasive EoE biomarkers and remaining gaps in biomarker validation.

METHODS

We performed a systematic review of EMBASE, Ovid MEDLINE, PubMed, and Web of Science from inception to June 6, 2017. Studies were included if patients met the 2007 consensus criteria for EoE diagnosis, a minimally invasive biomarker was assessed, and the study included at least 1 control for comparison.

RESULTS

The search identified 2094 studies, with 234 reviewed at full-text level, and 49 included in the analysis (20 adult, 19 pediatric, 7 pediatric and adult, and 3 not stated). Most (26 of 49) were published after 2014. Thirty-five studies included healthy controls, 9 analyzed atopic controls, and 29 compared samples from patients with active and inactive EoE. Minimally invasive biomarkers were obtained from peripheral blood (n = 41 studies), sponge or string samples (n = 3), oral or throat swab secretions (n = 2), breath condensate (n = 2), stool (n = 2), and urine (n = 2). The most commonly reported biomarkers were peripheral blood eosinophils (n = 16), blood and string eosinophil granule proteins (n = 14), and eosinophil surface or intracellular markers (n = 12). EoE biomarkers distinguished active EoE from healthy controls in 23 studies, atopic controls in 2 studies, and inactive EoE controls in 20 studies.

CONCLUSION

Several promising minimally invasive biomarkers for EoE have emerged; however, few are able to differentiate EoE from other atopic diseases.

Diagnosis, Natural History and Treatment of Eosinophilic Enteritis: a Review

PURPOSE OF REVIEW

To review recent findings regarding eosinophilic enteritis, including epidemiology, pathogenesis, natural history, and treatment.

RECENT FINDINGS

A 2017 population-based study using a US healthcare system database identified 1820 patients with a diagnosis of eosinophilic enteritis among 35,826,830 individuals. The majority of patients with eosinophilic enteritis in this study were women (57.7%), Caucasian (77.5%), and adults (> 18 years of age) (83.5%). The overall prevalence of eosinophilic enteritis was estimated at 5.1/100,000 persons. Eosinophilic enteritis, also known as eosinophilic gastroenteritis, is a rare primary eosinophilic gastrointestinal disorder (EGID) of unknown etiology characterized by the presence of an intense eosinophilic infiltrate on histopathological examination of the intestinal mucosa. The etiology of eosinophilic enteritis remains unknown. However, there is evidence to support the role of allergens in the pathogenesis of this disorder, as children and adults with EGIDs often have positive skin testing to food allergens and a family history of allergic diseases. Recent studies unraveling the role of IgE-mediated but also delayed Th2-type responses have provided insight into the pathogenesis of this disease. Eosinophilic enteritis causes a wide array of gastrointestinal symptoms such as abdominal pain, diarrhea, nausea, vomiting, bloating, or ascites, and its diagnosis requires a high degree of clinical likelihood, given the nonspecific clinical presentation and physical examination findings. Oral corticosteroids are considered to be the mainstay of treatment and are generally used for a short period with good response rates. Antihistamine drugs and sodium cromoglycate have also been used to treat patients with eosinophilic enteritis. Preliminary studies have demonstrated the potential benefit of biological therapies targeting the eosinophilic pathway such as mepolizumab, an anti-IL5 antibody, or omalizumab, an anti-IgE monoclonal antibody. Eosinophilic enteritis is generally considered to be a benign disease without relapse, but up to 50% of patients may present a more complex natural history characterized by unpredictable relapses and a chronic course.

Revisiting the NIH Taskforce on the Research needs of Eosinophil-Associated Diseases (RE-TREAD)

Eosinophil-associated diseases (EADs) are rare, heterogeneous disorders characterized by the presence of eosinophils in tissues and/or peripheral blood resulting in immunopathology. The heterogeneity of tissue involvement, lack of sufficient animal models, technical challenges in working with eosinophils, and lack of standardized histopathologic approaches have hampered progress in basic research. Additionally, clinical trials and drug development for rare EADs are limited by the lack of primary and surrogate endpoints, biomarkers, and validated patient-reported outcomes. Researchers with expertise in eosinophil biology and eosinophil-related diseases reviewed the state of current eosinophil research, resources, progress, and unmet needs in the field since the 2012 meeting of the NIH Taskforce on the Research of Eosinophil-Associated Diseases (TREAD). RE-TREAD focused on gaps in basic science, translational, and clinical research on eosinophils and eosinophil-related pathogenesis. Improved recapitulation of human eosinophil biology and pathogenesis in murine models was felt to be of importance. Characterization of eosinophil phenotypes, the role of eosinophil subsets in tissues, identification of biomarkers of eosinophil activation and tissue load, and a better understanding of the role of eosinophils in human disease were prioritized. Finally, an unmet need for tools for use in clinical trials was emphasized. Histopathologic scoring, patient- and clinician-reported outcomes, and appropriate coding were deemed of paramount importance for research collaborations, drug development, and approval by regulatory agencies. Further exploration of the eosinophil genome, epigenome, and proteome was also encouraged. Although progress has been made since 2012, unmet needs in eosinophil research remain a priority.

Biologic Agents for the Treatment of Hypereosinophilic Syndromes

Hypereosinophilic syndromes (HES) are a heterogeneous group of rare disorders defined by the presence of marked peripheral or tissue eosinophilia resulting in end-organ damage. Although conventional therapies, including glucocorticoids, hydroxyurea, and IFN-α, are initially effective in reducing eosinophilia and symptoms in a majority of patients with platelet-derived growth factor mutation-negative HES, the development of resistance and treatment-related toxicity are common. In contrast, targeted therapy with the tyrosine kinase inhibitor, imatinib, is well tolerated but effective only in the subset of patients with HES with a primary myeloid disorder. Eosinophil-targeted biotherapeutics offer the potential of improved efficacy with few, if any, adverse effects. The aims of this review are to provide an overview of current approaches to the use of conventional HES therapies and a discussion of existing biotherapeutics that target eosinophils and their potential use in the treatment of HES. With the continuing expansion of eosinophil-targeted biotherapeutics, the future for patients with eosinophilic disorders is promising.

Systematic review of histological remission criteria in eosinophilic esophagitis

Elemental diets, dietary elimination, and steroid therapies are the most common therapies in the clinical trials for eosinophilic esophagitis (EoE). Histological findings (usually reported as eosinophils per microscopic high‐powered field [hpf]) remain the most common end‐point used to define response. Yet, the threshold for defining “response” and “remission” are ill‐defined among consensus guidelines and may vary from study to study. We conducted a systematic literature review of articles on eosinophilic esophagitis, published between January 2007 and November 2017, considering histological remission as the primary outcome. We abstracted treatment information and definitions of histological remission or response. A comparison of definitions of histological remission across and within institutions was performed. A total of 61 articles were included in this review, with approximately 60% of the studies published from centers in the United States. Histological definitions of remission of EoE ranged from 0 to ≤20 eosinophils/hpf. The most stringent criteria, ranging from 0 to ≤5 eosinophils/hpf, were commonly used in interventional trial studies that examined the effects of new treatments. We found remarkable variability in definitions between studies, treatment types, and regions. Age or epidemiological distribution of study subjects did not influence the criteria for histological remission. Clinical and histological improvements are important measures of the effects of treatment. Histological findings, the most objective measure of treatment, should provide an optimal method for comparing the effectiveness of various treatments. Yet, our findings suggest a lack of consistent remission criteria in published studies. Considering these inconsistencies, it is difficult to compare the effectiveness of various treatments.

Emerging drugs for eosinophilic esophagitis

INTRODUCTION

Eosinophilic esophagitis (EoE) is rare but incidence and prevalence is increasing. EoE is characterized by eosinophilic inflammation of the esophagus causing gastrointestinal symptoms such as abdominal pain, vomiting, reflux, dysphagia, and food impactions. If untreated, remodeling and fibrosis of the esophagus can occur and stricture formation may result. Current treatment options are limited to food-restriction diets or medications including proton pump inhibitors (PPIs) or swallowed corticosteroids. Significant progress has been made in understanding the underlying mechanisms of EoE allowing for development of drugs that target specific points in EoE pathways. Investigation of these drugs is early with few controlled studies, but many show promise as future treatments. Areas covered: This review will provide an up to date discussion of current therapies and investigational drugs for EoE. Articles used in this review were retrieved from PubMed. Ongoing or completed clinical trials were obtained through clinicaltrials.gov and review of the PharmaProjects database. Expert Opinion: Multiple therapeutic targets have been identified and several have shown efficacy. Work is needed to define appropriate trial outcome measures. Collaboration between government agencies, patient advocacy groups, and investigator-led consortia is critical for completing new clinical trials which should pave the way for new therapies in clinical practice.

Role of the β Common (βc) Family of Cytokines in Health and Disease

The β common ([βc]/CD131) family of cytokines comprises granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3, and IL-5, all of which use βc as their key signaling receptor subunit. This is a prototypic signaling subunit-sharing cytokine family that has unveiled many biological paradigms and structural principles applicable to the IL-2, IL-4, and IL-6 receptor families, all of which also share one or more signaling subunits. Originally identified for their functions in the hematopoietic system, the βc cytokines are now known to be truly pleiotropic, impacting on multiple cell types, organs, and biological systems, and thereby controlling the balance between health and disease. This review will focus on the emerging biological roles for the βc cytokines, our progress toward understanding the mechanisms of receptor assembly and signaling, and the application of this knowledge to develop exciting new therapeutic approaches against human disease.

Biological therapies for eosinophilic gastrointestinal diseases

The scientific basis and the clinical application of mAb therapies that target specific immunologic pathways for eosinophilic gastrointestinal diseases are areas of active interest. There is a growing recognition of a subset of patients with eosinophilic esophagitis whose disease does not respond well to topical steroids or elimination diets. In addition, long-term use of corticosteroids presents possible risks that are currently being evaluated. Systemic therapy with a biologic agent offers potential advantages as a global approach that could limit the need for multiple, locally active medical therapies and allergen avoidance. The identification of novel biologic strategies is ongoing, and the recent validation of instruments and outcome measures to assess disease activity has proved essential in demonstrating efficacy. Studies using biologics that target IL-13 pathways in the treatment of eosinophilic esophagitis have demonstrated substantial promise.

Treatment of eosinophilic esophagitis in the pediatric patient: an evidence-based approach

Eosinophilic esophagitis (EoE) is a unique form of non-IgE-mediated food allergy characterized by esophageal eosinophilic infiltration that commonly causes dysphagia and food impaction in children and adolescents. Assessing the efficacy of dietary restrictions or drug therapies to achieve clinical and histologic resolution of EoE through randomized controlled trials and meta-analyses has resulted in new evidence-based guidelines. Avoiding food triggers is the only therapy targeting the cause of the disease. None of the currently available food allergy tests adequately predict food triggers for EoE. Exclusively feeding with an amino acid-based elemental diet and empiric six-food elimination diet (avoiding the six foods most commonly related with food allergy) has consistently provided the best cure rates, but their high level of restriction and need for multiple endoscopies are deterrents for implementation. Simpler and less restrictive empirical methods, like a four-food (milk, gluten-containing cereals, egg, legumes) or a two-food (milk and gluten) elimination diet, show encouraging results. Proton pump inhibitors are currently a first-line treatment, achieving histological remission and improvement of symptoms in 54.1 and 64.9% of pediatric EoE patients, respectively. The efficacy of topical corticosteroids in EoE assessed in several trials and summarized in meta-analyses indicates that budesonide and fluticasone propionate are significantly superior to placebos, both in decreasing eosinophil mucosal infiltration and in relieving symptoms. Owing to differences in drug delivery, viscous budesonide formulas seem to be the best pharmacological therapy for EoE.

CONCLUSION

Applying evidence-based therapies and a practical management algorithm provide an effective control of EoE. What is Known: • Eosinophilic esophagitis (EoE) now constitutes the main cause of dysphagia and food impaction in children, adolescents, and young adults. • Its chronic course and frequent progression to subepithelial fibrosis leading to strictures and narrow-caliber esophagus indicate the need for treatment. What is New: • Therapeutic goals in children with EoE include resolution of esophageal symptoms, to cure esophageal inflammation (mucosal healing) and restore a proper esophageal caliber in case of fibrostenotic endoscopic findings. Avoiding iatrogenic drug effects and nutritional deficiencies, as well as maintaining an adequate quality of life, is also essential. • Novel evidence-based guidelines, endorsed by several European scientific societies, incorporate recent advances in knowledge from several randomized controlled trials and systematic reviews to provide the best standard of care to pediatric patients, by following simple management algorithms.

New biologics for allergic diseases

INTRODUCTION

Allergic conditions such as asthma and atopic dermatitis have a high prevalence but represent a heterogeneous group of diseases despite similar clinical presentation and underlying pathophysiology. A better understanding of the phenotypes and endotypes of these diseases has driven rapid development of biologic medications targeting many steps of the inflammatory pathways. Areas covered: There are 2 major inflammatory pathways that drive allergic diseases: Type-2 (Th-2) inflammation and non-type 2 inflammation. All of the biologic medications currently approved for use, and most of the biologic medications under development for allergic diseases have focused on the Th-2 inflammatory pathway. Biologic targets along this pathway include Anti-Immunoglobulin E (IgE), Anti-Interleukin 5 (IL-5), Anti-IL 4, and Anti-IL 13. Although the most study has been done in the realm of severe asthma, biologic targets for other allergic diseases including atopic dermatitis, chronic rhinosinusitis with nasal polyposis, chronic idiopathic urticaria, eosinophilic esophagitis, and eosinophilic granulomatosis with polyangiitis are also discussed. Expert commentary: Novel biologic therapies have emerged over the last several years that have revolutionized the management of patients with refractory allergic disease.

Targeting the Interleukin-5 Pathway for Treatment of Eosinophilic Conditions Other than Asthma

Improved understanding of the contribution of eosinophils to various chronic inflammatory conditions, most notably allergic asthma, has encouraged development of monoclonal antibodies specifically targeting mediators and surface receptors involved in eosinophil expansion and activation. The pivotal role of interleukin-5 (IL-5) in eosinophil biology, its high specificity for this leukocyte subset, and its involvement in the majority of eosinophilic conditions make it a very enticing target for treatment of eosinophil-mediated disorders. Two types of antibodies have been developed to target eosinophils: antibodies against IL-5 (mepolizumab and reslizumab), and an antibody against the IL-5-receptor-alpha-chain (IL-5Rα) (benralizumab). Both types of antibodies prevent IL-5 from engaging its receptor and in addition, anti-IL-5Rα antibodies induce target-cell lysis. They have been shown to reduce circulating eosinophil counts rapidly in humans with various disorders. Herein, a brief overview of the role of IL-5 in eosinophil biology will be presented, followed by a description of the development and characteristics of antibodies targeting IL-5 or its receptor. Results of clinical trials evaluating the efficacy and safety of these new antibodies in diseases (other than eosinophilic asthma) with prominent tissue eosinophilia are reviewed, followed by safety considerations and potential future applications.

Targeting Interleukin-5 or Interleukin-5Rα: Safety Considerations

Asthma is a highly prevalent chronic disease of the airways; approximately 10% of patients with asthma will experience a severe form of the disease. New understanding of the pathogenesis of asthma has enabled the development of novel drugs and provided hope for patients with asthma. Interleukin (IL)-5 and IL-5 receptor subunit α (IL-5-Rα) plays a crucial role in the development, maturation, and operation of eosinophils so were the first important therapeutic target of these new drugs. While the results of early clinical trials of these drugs were not promising, results improved once researchers discovered the drugs worked best in patients with high eosinophil levels. Patients treated with both anti-IL-5 and IL-5-Rα experienced significant decreases in exacerbations. Trials have also demonstrated promising safety profiles; adverse events have been few and frequently only observed with placebo or considered unrelated to the study drug. The positive efficacy and safety profiles of these drugs has led to trials with interesting results in other diseases that are also secondary to the action of eosinophils: Churg-Strauss syndrome, hypereosinophilic syndrome, nasal polyposis, chronic obstructive pulmonary disease, atopic dermatitis, and esophagitis. In this review, we explore the main clinical trials of anti-IL-5 and IL-5-Rα, both in asthma and in other pathologies, with particular reference to the interesting safety and efficacy results.

New Developments in the Diagnosis, Therapy, and Monitoring of Eosinophilic Esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) has transformed over the past two decades from a little-known entity to a significant cause of morbidity in the adult and pediatric population. We reviewed the most recent advancements in the diagnosis, therapy, and long-term monitoring of EoE.

RECENT FINDINGS

Based on clinical, endoscopic, histologic, immunologic, and genetic similarities, there is growing consensus to move away from distinguishing proton pump inhibitor responsive esophageal eosinophilia as an entity distinct from EoE. An increasing number of studies have identified duration of untreated disease as an important determinant of esophageal stricture formation. New approaches to the empiric elimination diet including one, two, four, and step-up protocols were developed to reduce the need for repeated endoscopies during reintroduction of food triggers. Topical steroids remain the mainstay of medical therapy but newer formulations are under development to optimize esophageal delivery. Novel, disease activity monitoring techniques are being evaluated that assess esophageal inflammatory activity without the need for endoscopy. Understanding of EoE has increased remarkably from the first identification of the disease. The underlying pathogenesis continues to be explored leading to shifts in diagnostic criteria as well as novel therapeutic targets. Innovative methods to monitor disease are under investigation and more research is needed to understand the natural history of EoE.

TGF-β1 alters esophageal epithelial barrier function by attenuation of claudin-7 in eosinophilic esophagitis

Barrier dysfunction has been implicated in the pathophysiology of eosinophilic esophagitis (EoE). Transforming growth factor-β1 (TGF-β1), a potent pleiotropic molecule, is increased in EoE; however, no study has evaluated its influence on esophageal epithelial barrier. We hypothesized that TGF-β1 regulates barrier dysfunction in EoE. We aimed to determine the role of TGF-β1 in the epithelial barrier in models of EoE. To examine the impact of TGF-β1 on esophageal barrier, immortalized human esophageal epithelial (EPC2-hTERT) cells were exposed to TGF-β1 during the three-dimensional air-liquid interface (3D-ALI) model in vitro. TGF-β1 exposure diminished EPC2-hTERT barrier function as measured by transepithelial electrical resistance (TEER) and 3 kDa Fluorescein isothiocyanate dextran paracellular flux (FITC Flux), and hematoxylin and eosin (H&E) assessment revealed prominent cellular separation. In analysis of epithelial barrier molecules, TGF-β1 led to the specific reduction in expression of the tight-junction molecule, claudin-7 (CLDN7), and this was prevented by TGF-β-receptor I inhibitor. Short hairpin ribonucleic acid (shRNA)-mediated CLDN7 knockdown diminished epithelial barrier function, whereas CLDN7 overexpression resulted in protection from TGF-β1-mediated barrier dysfunction. In pediatric EoE biopsies CLDN7 expression was decreased and altered localization was observed with immunofluorescence analysis, and the TGF-β1 downstream transcription factor, phosphorylated SMAD2/3 (pSMAD2/3), was increased. Our data suggest that TGF-β1 participates in esophageal epithelial barrier dysfunction through CLDN7 dysregulation.

Cytokine-targeting biologics for allergic diseases

OBJECTIVE

Asthma and allergic diseases continue to increase in prevalence, creating a financial burden on the health care system and affecting the quality of life for those who have these diseases. Many intrinsic and extrinsic factors are involved in the initiation and maintenance of the allergic response. Cytokines are proteins with growth, differentiation, and activation functions that regulate and direct the nature of immune responses.

DATA SOURCES

clinicaltrials.gov and PubMed.

STUDY SELECTIONS

Relevant clinical trials and recent basic science studies were chosen for discussion.

RESULTS

Many cytokines have been implicated in the development and perpetuation of the allergic response. Biologics have been and are continuing to be developed that target these molecules for use in patients with asthma and atopic dermatitis where standard treatment options fail. The current state of cytokine-targeting therapies is discussed.

CONCLUSION

This review focused on cytokines involved in the allergic response with an emphasis on those for which therapies are being or have been developed.

Biologics for asthma and allergy

PURPOSE OF REVIEW

The development of monoclonal antibody-based biologics targeted at inhibition of the Th2 cytokines interleukin-4, interleukin-5 and interleukin-13 represent potentially effective treatments for asthma and allergic diseases. This short review is based on English-language original articles in PubMed or MedLine that reported significant clinical findings on the evidence demonstrating the effectiveness or otherwise of the targeting of interleukin-4, interleukin-5 or interleukin-13 in asthma or allergic disease.

RECENT FINDINGS

Asthma exhibits marked heterogeneity both clinically and at the molecular phenotypic level requiring specifically targeted treatments to block the key pathways of the disease. It is becoming apparent that significant clinical effects with anticytokine-based biologic therapies are more likely in carefully selected patient populations that take asthma phenotypes into account. Biologics aimed at interleukin-4/13, interleukin-5 or immunoglobulin E are potentially effective treatments for patients with difficult to treat allergic disease. The development of reproducible and straightforward discriminatory biomarkers may aid identification of those patients most likely to benefit from treatment with these expensive interventions.

SUMMARY

Overall these biologics-based therapies are effective treatments for difficult to treat asthma and allergic disease with a safety profile comparable with placebo in the majority of published studies.

Future Directions in Eosinophilic Esophagitis

Eosinophilic esophagitis advances parallel the increased prevalence. Developments include refining the diagnostic criteria, identifying risk factors, appreciating the contribution of inflammatory pathways, recognizing the importance of subepithelial remodeling, validating trial endpoints, defining a role for biological therapies, and optimizing dietary therapy. Endoscopic outcomes have emerged as endpoints in trials of novel therapeutics. Expanding efforts seek to develop less-invasive methods to assess disease activity thereby reducing the burden of repeated endoscopic procedures during elimination diets. The functional lumen imaging probe is now identified as a determinant of complications with potential utility as a therapeutic endpoint.

Diagnosis and Treatment of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a new disease. It is caused by a T-helper type 2 cell response to food antigens in contact with the esophageal mucosa. Although no single feature defines EoE, a constellation of compatible demographic, clinical, endoscopic, and histologic findings establish the diagnosis. Children present with symptoms and endoscopic patterns characteristic of inflammation, whereas adolescents and adults have manifestations of fibrosis and gross esophageal strictures. Clinical and endoscopic scoring systems have helped to standardize diagnosis. There is controversy in EoE research over the optimal endpoint for treatment. Although the most common endpoint is a reduced number of eosinophils in biopsies, changes in symptoms and endoscopic features are becoming important targets of therapy. We should improve our understanding of EoE progression and the need for maintenance therapy, and continue development of diagnostic tools that avoid endoscopy and biopsy analyses to more easily monitor disease activity.

Pharmacologic Treatment of Eosinophilic Esophagitis: An Update

Eosinophilic esophagitis (EoE) is defined as a chronic, immune-medicated or antigen-mediated, esophageal disease, characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation. Food allergens are identified in most patients. Treatment strategies include elimination diets, drugs, and esophageal dilation. This article focuses on pharmacologic treatment. Currently, there is no pharmacologic treatment that has been approved by regulatory authorities. Established pharmacologic options to treat EoE include proton pump inhibitors and swallowed topical steroids. Several biologic therapies are currently under evaluation and some of them have shown promising results in improving biologic endpoints and patient-reported outcomes.

Eosinophilic Esophagitis: Pathophysiology and Definition

Eosinophilic esophagitis is an adaptive immune response to patient-specific antigens, mostly foods. Eosinophilic esophagitis is not solely IgE-mediated and is likely characterized by Th2 lymphocytes with an impaired esophageal barrier function. The key cytokines and chemokines are thymic stromal lymphopoeitin, interleukin-13, CCL26/eotaxin-3, and transforming growth factor-β, all involved in eosinophil recruitment and remodeling. Chronic food dysphagia and food impactions, the feared late complications, are related in part to dense subepithelial fibrosis, likely induced by interleukin-13 and transforming growth factor-β.

Biomarkers for severe eosinophilic asthma

The last decade has seen the approval of several new biologics for the treatment of severe asthma-targeting specific endotypes and phenotypes. This review will examine how evidence generated from the mepolizumab clinical development program showed that blood eosinophil counts, rather than sputum or tissue eosinophil counts, evolved as a pharmacodynamic and predictive biomarker for the efficacy of treatment with mepolizumab in patients with severe eosinophilic asthma. Based on the available evidence and combined with clinical judgement, a baseline blood eosinophil threshold of 150 cells/μL or greater or a historical blood eosinophil threshold of 300 cells/μL or greater will allow selection of patients with severe eosinophilic asthma who are most likely to achieve clinically significant reductions in the rate of exacerbations with mepolizumab treatment.

Clinical and Biological Markers in Hypereosinophilic Syndromes

Hypereosinophilic syndromes (HES) are rare, heterogeneous syndromes characterized by markedly elevated eosinophil counts in the blood and/or tissue and evidence of eosinophil-associated pathology. Although parasitic infections, drug hypersensitivity, and other disorders of defined etiology can present as HES (associated HES), treatment is directed at the underlying cause rather than the eosinophilia itself. A number of additional subtypes of HES have been described, based on clinical and laboratory features. These include (1) myeloid HES—a primary disorder of the myeloid lineage, (2) lymphocytic variant HES—eosinophilia driven by aberrant or clonal lymphocytes secreting eosinophil-promoting cytokines, (3) overlap HES—eosinophilia restricted to a single organ or organ system, (4) familial eosinophilia—a rare inherited form of HES, and (5) idiopathic HES. Since clinical manifestations, response to therapy, and prognosis all differ between HES subtypes, this review will focus on clinical and biological markers that serve as markers of disease activity in HES (excluding associated HES), including those that are likely to be useful only in specific clinical subtypes.

Biologic Therapies for Immunoglobulin E-mediated Food Allergy and Eosinophilic Esophagitis

Immunoglobulin (Ig) E-mediated food allergy and eosinophilic esophagitis (EoE) are chronic, allergen-mediated disorders characterized by an aberrant TH2 immune response. The development and investigation of biologics for the treatment of IgE-mediated food allergy and eosinophilic esophagitis have provided further insight into the pathophysiology and management of these disorders. This article provides an overview of biologic therapies that are being investigated or have potential as treatments for IgE-mediated food allergy and eosinophilic esophagitis. Identification of EoE phenotypes that are responsive to biologics and investigation of biologics combined with other therapies may help elucidate a role for biologics in EoE.

Eosinophilic Esophagitis in Children

PURPOSE OF REVIEW

EoE is a significant cause of gastrointestinal morbidity affecting 1:2000. Patients with EoE typically have multiple atopic comorbidities, and additionally, many patients with EoE can be controlled well with elimination diets. The purpose of this review is to summarize the care of pediatric eosinophilic esophagitis patients.

RECENT FINDINGS

EoE represents a distinct clinical syndrome which is characterized by esophageal dysfunction and eosinophil-predominant inflammation of the esophageal mucosa. Patients with EoE can present with varying symptoms depending on their age; in this review, we review the presenting features of eosinophilic esophagitis in children as well as a diagnostic algorithm for EoE. The mucosal inflammation in EoE is driven by exposure to food antigens in many patients with EoE. Therefore, for the majority of patients, the mainstays of treatment remain food elimination diets or swallowed steroids. This review summarizes the diagnostic approach to eosinophilic esophagitis (EoE) in pediatric patients, focusing on the importance of accurate diagnosis and selection of appropriate therapy.

Diagnosis and Management of Eosinophilic Esophagitis

Unlike traditional food allergies, immunoglobulin E (IgE) is not a key mediator of eosinophilic esophagitis (EoE). Nonetheless, foods antigens are important triggers of EoE, and allergists play an important role in management of this chronic disease. This review addresses insights into the diagnosis and management as it relates to our evolving understanding about the pathogenesis of EoE.

Current concepts in eosinophilic esophagitis

Background

Eosinophilic esophagitis (EoE) is a disease entity first described in the 1990s, but showing an increasing incidence that is characterized clinically by esophageal dysfunction and histologically by a striking eosinophil infiltration.

Methods

This article discusses new aspects of the pathogenesis, symptoms, diagnosis, and treatment of EoE.

Results

EoE affects both children and adults and is frequently associated with atopic disease and IgE sensitization. Barrier dysfunction and T‑helper 2 inflammation are considered to be pathogenetically important factors. Recently, a proton pump inhibitor (PPI)-sensitive EoE subtype as well as an EoE-like disorder have been described.

Conclusion

Research in recent years has contributed to a better understanding of the disease spectrum and pathogenesis of EoE, including genetic dispositions, thereby laying the foundation for innovative treatment approaches.

Psychometric validation of the Dysphagia Symptom Questionnaire in patients with eosinophilic esophagitis treated with budesonide oral suspension

Background

Eosinophilic esophagitis (EoE) is characterized by high levels of eosinophils in the esophageal mucosa. Patients with the disease present with a range of symptoms, including dysphagia (difficulty swallowing). The aim of this analysis was to assess the psychometric properties of the Dysphagia Symptom Questionnaire (DSQ), a patient-reported outcome (PRO) measure of dysphagia associated with EoE. Psychometric properties of the DSQ were assessed using data collected from a 12-week, phase 2, multicenter, randomized, double-blind, placebo-controlled trial of budesonide oral suspension in adolescents and adults (11–40 years old) with EoE.

Results

The study population comprised 93 patients with EoE; 94.6% of whom were white, 68.8% were male and the mean age (standard deviation) was 21.6 (7.7) years. Patients had been diagnosed with EoE for a mean of 37.6 months before study initiation. The DSQ was feasible to implement with few item-level data missing at baseline. Item discrimination was high, with floor and ceiling effects below the predefined threshold (≤9%). Higher DSQ scores corresponded with presence and increased severity of dysphagia, indicative of strong item discrimination among patients at baseline (threshold >50%). The DSQ was able to detect changes in symptoms over time and produced similar outcomes to those from physician- and other patient-rated measures, supportive of construct validity. The DSQ had strong test–retest reliability (intraclass correlation coefficient, r = 0.82); and was also responsive to disease-level changes, with higher DSQ scores corresponding to increased esophageal eosinophilic burden. Lastly, the percentage changes in the minimal clinically important difference and clinically important difference in DSQ score were estimated at −27.4% and −55.4%, respectively.

Conclusions

These analyses support the DSQ as a valid and reliable measure of dysphagia in patients with EoE. Changes in DSQ scores suggest a level of agreement between clinician, patient and histologic response. The DSQ should therefore be considered a viable PRO measure of dysphagia for use in future therapeutic studies of EoE.

Management of Eosinophilic Esophagitis Based on Pathophysiological Evidence

Over the past decades eosinophilic esophagitis (EoE) has been increasingly diagnosed, and significant progress has been made in our understanding of its pathophysiology. As EoE cannot be cured yet, treatment goals are suppression of disease activity and symptoms as well as the prevention of progression to a more severe disease phenotype. Disease-modifying treatment options can be divided into dietary therapy and immunosuppressive medications, of which topical steroids have been most investigated, yet are still prescribed off-label. In this review, we will summarize recent advances in our understanding of EoE and discuss the mechanisms of action of current treatment options, with emphasis on the role of the esophageal epithelial barrier and the effects of proton-pump inhibitors in the management of patients with EoE.

Management of refractory eosinophilic oesophagitis

The goal of this Review is to discuss the clinical approach to patients who do not respond to treatment for eosinophilic oesophagitis (EoE). Refractory EoE is challenging to manage as there are limited data to guide decision-making. In this Review, refractory EoE is defined as persistent eosinophilia in the setting of incomplete resolution of the primary presenting symptoms and incomplete resolution of endoscopic findings following a PPI trial, and after treatment with either topical steroids or dietary elimination. However, this definition is controversial. This Review will examine these controversies, explore how frequently non-response is observed, and highlight potential explanations and predictors of non-response. Non-response is common and affects a large proportion of patients with EoE. It is important to systematically assess multiple possible causes of non-response, as well as consider treatment complications and an incorrect diagnosis of EoE. If non-response is confirmed, second-line treatments are required. Although the overall response rate for second-line therapy is disappointing, with only half of patients eventually responding, there are several promising agents that are currently under investigation, and the future is bright for new treatment modalities for refractory EoE.

Targeting granulocyte-macrophage colony-stimulating factor in epithelial and vascular remodeling in experimental eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic antigen-mediated clinicopathologic disease of the esophagus characterized by an eosinophil-predominant inflammatory infiltrate. A clinical hallmark is extensive tissue remodeling including basal zone hyperplasia, fibrosis, and angiogenesis. However, the cellular mechanisms responsible for these processes are not fully defined. We hypothesized that targeting granulocyte-macrophage colony-stimulating factor (GM-CSF; an agonist cytokine linked with eosinophil survival and activation) would be protective in a preclinical model of EoE.

METHODS

Eosinophilic esophagitis-like esophageal inflammation was induced in the L2-IL5^OXA EoE mouse model, and GM-CSF production was assessed by mRNA and protein analyses. Granulocyte-macrophage colony-stimulating factor-receptor-alpha expression patterns were examined by flow cytometric and immunofluorescence analysis. L2-IL5^OXA EoE mice were treated with anti-GM-CSF neutralizing antibody or isotype control and assessed for histopathological indices of eosinophilia, epithelial hyperplasia, and angiogenesis by immunohistochemistry and RT-PCR.

RESULTS

Significantly increased levels of esophageal GM-CSF expression was detected in the L2-IL5^OXA mouse EoE model during active inflammation. Granulocyte-macrophage colony-stimulating factor-receptor-alpha was predominantly expressed on esophageal eosinophils during EoE, in addition to select cells within the lamina propria. Anti-GM-CSF neutralization in L2-IL5^OXA EoE mice resulted in a significant diminution of epithelial eosinophilia in addition to basal cell hyperplasia and vascular remodeling. This treatment response was independent of effects on esophageal eosinophil maturation or activation.

CONCLUSION

Granulocyte-macrophage colony-stimulating factor is a potential therapeutic target to reduce esophageal eosinophilia and remodeling.

White Paper AGA: Drug Development for Eosinophilic Esophagitis

Since first characterized in 2 small case series in the early 1990s, eosinophilic esophagitis (EoE) has emerged as a commonly identified cause of esophageal symptoms in children and adults.1,2 Although several highly effectively dietary, pharmacologic, and endoscopic therapies have been reported, none is currently approved by either the US Food and Drug Administration (FDA) or European regulatory authorities. Evolving diagnostic criteria have challenged drug development, in particular the recognition of complex interactions with the most prevalent esophageal disorder, gastroesophageal reflux disease (GERD). Heterogeneity in the clinical presentations of affected children and adults has created difficulties with uniform inclusion criteria and the development of disease-specific, patient-reported outcome (PRO) instruments. Furthermore, controversies regarding the appropriate therapeutic endpoints of EoE have impeded the design of clinical trials. Despite these obstacles, collaborative efforts by investigators, industry, the FDA, and patient advocacy groups have resulted in substantial progress in drug development in EoE over the past 2 decades.3 The purpose of this article is to summarize discussions on EoE based on the 2016 Drug Development Conference sponsored by the Center for Diagnostics and Therapeutics of the American Gastroenterological Association.

Bidirectional Mast Cell-Eosinophil Interactions in Inflammatory Disorders and Cancer

Human mast cells (MCs) and eosinophils were first described and named by Paul Ehrlich. These cells have distinct myeloid progenitors and differ morphologically, ultrastructurally, immunologically, biochemically, and pharmacologically. However, MCs and eosinophils play a pivotal role in several allergic disorders. In addition, these cells are involved in autoimmune disorders, cardiovascular diseases, and cancer. MCs are distributed throughout all normal human tissues, whereas eosinophils are present only in gastrointestinal tract, secondary lymphoid tissues, and adipose tissue, thymus, mammary gland, and uterus. However, in allergic disorders, MCs and eosinophils can form the "allergic effector unit." Moreover, in several tumors, MCs and eosinophils can be found in close proximity. Therefore, it is likely that MCs have the capacity to modulate eosinophil functions and vice versa. For example, interleukin 5, stem cell factor, histamine, platelet-activating factor (PAF), prostaglandin D2 (PGD2), cysteinyl leukotrienes, and vascular endothelial growth factors (VEGFs), produced by activated MCs, can modulate eosinophil functions through the engagement of specific receptors. In contrast, eosinophil cationic proteins such as eosinophil cationic protein and major basic protein (MBP), nerve growth factor, and VEGFs released by activated eosinophils can modulate MC functions. These bidirectional interactions between MCs and eosinophils might be relevant not only in allergic diseases but also in several inflammatory and neoplastic disorders.

A Mathematical Modeling Approach to Understanding the Effect of Anti-Interleukin Therapy on Eosinophils

Emerging T‐helper type 2 (Th₂) cytokine‐based asthma therapies, such as tralokinumab, lebrikizumab (anti‐interleukin (IL)‐13), and mepolizumab (anti‐IL‐5), have shown differences in their blood eosinophil (EOS) response. To better understand these effects, we developed a mathematical model of EOS dynamics. For the anti‐IL‐13 therapies, lebrikizumab and tralokinumab, the model predicted an increase of 30% and 10% in total and activated EOS in the blood, respectively, and a decrease in the total and activated EOS in the airways. The model predicted a rapid decrease in total and activated EOS levels in blood and airways for the anti‐IL‐5 therapy mepolizumab. All model‐based predictions were consistent with published clinical observations. The modeling approach provided insights into EOS response after treatment with Th₂‐targeted therapies, and supports the hypothesis that an increase in blood EOS after anti‐IL‐13 therapy is part of the pharmacological action of these therapies.

Patient profiles and clinical utility of mepolizumab in severe eosinophilic asthma

Mepolizumab (Nucala^®) is an effective and specific anti-eosinophil molecular therapy that has recently been approved as add-on therapy for the management of severe eosinophilic asthma by the US Food and Drug Administration (FDA), European Medicines Agency (EMA; European Union) and more recently National Institute for Health and Care Excellence (NICE; UK). It is one of several molecular therapies in development for this indication and is illustrative of the strategic trajectory for pharmaceutical drug development taken over the past decade in several disease areas. Molecular therapies offer the prospect of improved specificity and effectiveness of biological effect. However, this necessitates a clear understanding of the underlying mechanistic pathways underpinning pathological processes, to inform drug development that yields novel more efficacious treatment options with a better clinical profile than existing agents. For the first time, utilization of molecular therapies in clinical trials is providing a novel in vivo model to characterize the association between specific pathways and clinical disease expression. It is increasingly recognized that asthma exhibits both clinical and pathological heterogeneity. It follows that a one-size-fits-all approach will not be appropriate and cost-effectiveness may only be achieved by identifying responder subgroups. This so-called personalized approach to therapy is being supported by the parallel development of companion biomarkers for clinical application. In this review, the author summarizes the clinical studies, their interpretation and the lessons learnt with mepolizumab that have informed our understanding of the approach to personalized molecular therapy in asthma.

Multi-morbidities of allergic rhinitis in adults: European Academy of Allergy and Clinical Immunology Task Force Report

This report has been prepared by the European Academy of Allergy and Clinical Immunology Task Force on Allergic Rhinitis (AR) comorbidities. The aim of this multidisciplinary European consensus document is to highlight the role of multimorbidities in the definition, classification, mechanisms, recommendations for diagnosis and treatment of AR, and to define the needs in this neglected area by a literature review. AR is a systemic allergic disease and is generally associated with numerous multi-morbid disorders, including asthma, eczema, food allergies, eosinophilic oesophagitis (EoE), conjunctivitis, chronic middle ear effusions, rhinosinusitis, adenoid hypertrophy, olfaction disorders, obstructive sleep apnea, disordered sleep and consequent behavioural and educational effects. This report provides up-to-date usable information to: (1) improve the knowledge and skills of allergists, so as to ultimately improve the overall quality of patient care; (2) to increase interest in this area; and (3) to present a unique contribution to the field of upper inflammatory disease.