Benralizumab Completely Depletes Gastrointestinal Tissue Eosinophils and Improves Symptoms in Eosinophilic Gastrointestinal Disease

Therapeutic Challenges and Emerging Strategies for T674I and PTPN11 Mutations in a FIP1L1-PDGFRA-Positive Myeloproliferative Neoplasm: A Case Report

Myeloproliferative neoplasm (MPN) with eosinophilia associated with FIP1L1-PDGFRA is a rare eosinophilic disorder typically treated with imatinib. However, resistance due to the T674I mutation poses a significant challenge. This case presents the first reported instance of concurrent FIP1L1-PDGFRA T674I and PTPN11 (p.E76D) mutations in a 38-year-old male patient with MPN and eosinophilia. The patient initially responded to imatinib but developed resistance after ten months, leading to severe spinal cord compression caused by granulocytic sarcoma. Despite undergoing radiotherapy, chemotherapy, and allogeneic hematopoietic stem cell transplantation (allo-HSCT), the disease progressed. Although full donor chimerism was achieved post-transplant, the patient relapsed shortly afterward with eosinophilia, splenomegaly, and constitutional symptoms. Further treatments, including sorafenib and decitabine, failed to control the disease, and the patient ultimately died from multiorgan failure. This case illustrates the therapeutic challenges associated with FIP1L1-PDGFRA T674I-positive eosinophilic disorder, especially when compounded by the PTPN11 mutation. Resistance to standard treatments underscores the urgent need for novel therapies to manage this rare and aggressive disease.

Effect of Biologics against Interleukin-5 Administered to Patients with Eosinophilic Gastroenteritis1

Biologics against interleukin-5 were administered to five patients with eosinophilic gastroenteritis (EGE) and bronchial asthma (BA). BA and abdominal symptoms as well as changes in steroid dose and the blood eosinophil count were examined. The man-to-woman ratio was 1:4. The average age of onset was 63 years old. The duration of the disease was three to nine years. Four patients showed improved BA symptoms with mepolizumab or benralizumab, and three successfully discontinued steroids. Regarding abdominal symptoms, mepolizumab was effective in one of three cases, while benralizumab improved symptoms in three of four cases. Biologics targeting interleukin-5 are effective in some patients with EGE accompanied by BA.

Efficacy of anti-interleukin 5 therapy in hypereosinophilic syndrome: An updated systematic review and meta-analysis

Background: Hypereosinophilic syndromes (HES) are marked by persistent eosinophilia, absence of a primary cause, and evidence of eosinophil-mediated organ damage. HES presents a spectrum of clinical manifestations, with prognosis and treatment varying based on the subtype, including myeloid/lymphoid neoplasms and chronic eosinophilic leukemia, not otherwise specified. The primary treatment goal is to reduce eosinophil levels to prevent organ damage, typically by using glucocorticoids and immunosuppressive agents. However, these treatments often have limited efficacy and considerable adverse effects. Objective: Given the central role of interleukin (IL) 5 in eosinophil development and survival, this study aimed to assess the efficacy and safety of anti-IL-5 therapies in patients with HES. Methods: A systematic literature search was conducted on two data bases. The primary outcome was the reduction in absolute eosinophil count, and secondary outcomes included the incidence of flares and adverse events. Data Analysis was conducted, and forest plots were made for each outcome. Results: Four trials were included in the analysis. Ninety-five percent of the patients in the anti-IL-5 group showed a reduction in the absolute eosinophil count compared with 41% in the placebo group (risk ratio [RR] 2.32 [95% confidence interval {CI}, 1.67-3.22]; p = <0.00001; tau statistic (I²) = 0%). Anti-IL-5 therapy was associated with a lower incidence of disease flares, with 15% of the patients in the anti-IL-5 group who experienced flares compared with 30% in the placebo group (RR 0.50 [95% CI, 0.31-0.86]; p = 0.01; I² = 0%). The incidence of adverse events was similar between the two groups (RR 0.99 [95% CI, 0.91-1.07]; p = 0.81; I² = 0%). Conclusion: Anti-IL-5 therapies are effective in reducing eosinophil count and preventing disease flares in patients with HES.

Single-center off-label benralizumab use for refractory hypereosinophilic syndrome demonstrates satisfactory safety and efficacy

Introduction

Benralizumab is an interleukin 5-receptor-blocking drug registered for the treatment of eosinophilic asthma. It has proven efficient and safe in a small phase-II trial in hypereosinophilic syndrome and is currently being investigated in a larger, randomized phase-III trial. We report on real-world experience with benralizumab in 15 patients with severe Hypereosinophilic syndrome (HES) that were refractory to other treatments or on unacceptable steroid doses.

Methods

Fifteen patients with severe HES were treated with compassionate need benralizumab. The measured endpoints were a reduction in peripheral eosinophil count, a reduction of corticosteroid use, adverse events, and clinical response.

Results

All subgroups of HES were represented in this cohort and in the case of reactive HES, treatment of the primary cause did not lead to resolution of the eosinophilia. The median time of follow-up was 38 months. Twelve patients reached a normalized peripheral eosinophil count (< 0.05 × 109/L), while the remaining three patients also had a significant reduction from baseline.Of the eight patients initially treated with steroids, five patients were off steroids completely, and three patients had reduced dosages. Eight patients experienced complete symptom resolution, and five partial resolution. No serious adverse events were observed.

Conclusion

In conclusion, benralizumab is safe and effective for the treatment of HES.

Successful novel use of dupilumab for gastrointestinal involvement of idiopathic hypereosinophilic syndrome: case report and review of the literature

Hypereosinophilic syndrome (HES) is characterized by blood and tissue hypereosinophilia leading to organ damage. Gastrointestinal involvement is the third most common manifestation. We present a patient with idiopathic HES with secondary eosinophilic esophagitis (EoE), gastritis, and enteritis, corticosteroids-dependent, azathioprine- and mepolizumab-refractory. The patient achieved clinical and histopathologic remission following dupilumab treatment. A 28 year-old female presented with chronic episodic nausea and emesis since childhood and initial diagnosis of primary eosinophilic gastrointestinal disease (EGID), improved with corticosteroids, refractory to azathioprine. She was found to have peripheral eosinophilia and multifactorial anemia, with iron, B12, and folate deficiencies. Esophageal, gastric, duodenal, and terminal ileum biopsies showed significant eosinophilic infiltrate. Bone marrow biopsy at age 31 confirmed HES diagnosis. By age 32, she became total parental nutrition (TPN)-dependent. She failed trials of benralizumab and mepolizumab [anti-interleukin (IL)-5 inhibitors], and cromolyn (mast-cell stabilizer). After developing new esophageal stricture, we initiated dupilumab (IL-4/13 inhibitor), recently FDA-approved for EoE. After 9 weeks, esophageal stricture, gut tissue eosinophilia, and prior intestinal ulcerations resolved. She ceased TPN and is tolerating a non-restricted diet, with complete symptom resolution. Our patient's complete remission with dupilumab shows promise for broadening its use in treating GI involvement in HES, along with primary EGIDs.

Hypereosinophilic syndrome response to mepolizumab in the setting of a compassionate use program

Mepolizumab, an anti-interleukin-5 antibody, has been proven a safe and effective glucocorticoid (GC)-sparing drug for many patients with nonclonal hypereosinophilic syndrome (HES) and is now approved in many countries. It remains unclear, however, which patients are most likely to benefit from therapy and whether the currently approved dosing regimen is appropriate for all. This observational retrospective study included all patients with HES who were enrolled in the MHE104317 compassionate use program (CUP) in our center. Patient and disease characteristics, mepolizumab dosing, and both clinical and hematological responses to treatment were collected from medical files. Treatment responses and mepolizumab dosing requirements were analyzed according to disease characteristics. Eighteen patients with HES were enrolled in the CUP, of whom nine are still on treatment. The median duration of exposure to mepolizumab was 45 mo (maximum 18 yr). A lower number of affected organs, requirement for GC dosing ≤10 mg prednisone-equivalent, and single-organ HES were associated with a higher likelihood of complete response. Lymphocytic variant HES (L-HES) was less treatment-responsive, leading to withdrawal and/or requiring higher mepolizumab dosing to achieve some degree of disease control. In contrast, all patients with single-organ disease had a complete response that could often be maintained despite increasing between-dose intervals. Few potentially treatment-related adverse events were observed despite prolonged exposure. This study confirms the efficacy and safety of mepolizumab in HES, although patients with L-HES rarely experience a complete response. In contrast, patients with single-organ disease affecting the lungs are often super-responders, and decreasing mepolizumab dosing may be attempted.

Eosinophils respond to, but are not essential for control of an acute Salmonella enterica serovar Typhimurium infection in mice

Eosinophils are a highly abundant cell type in the gastrointestinal tract during homeostatic conditions, where they have recently been reported to take on an activated phenotype following colonization by the bacterial microbiota. To date, there have been few studies investigating whether eosinophils respond to infection with enteric bacterial pathogens and/or investigating the requirements for eosinophils for effective bacterial pathogen control. In this study, we investigated the response of eosinophils to an acute enteric infection of mice with the bacterial pathogen Salmonella enterica serovar Typhimurium. We also assessed whether eosinophil deficiency impacted Salmonella burdens in the intestinal tract or impacted the systemic dissemination of Salmonella following an oral infection of littermate wild-type BALB/cJ and eosinophil-deficient ΔdblGATA BALB/cJ mice. We found comparable Salmonella burdens in the intestinal tract of wild-type and eosinophil-deficient mice and no significant differences in the levels of Salmonella disseminating to systemic organs within 3 days of infection. Despite our evidence suggesting that eosinophils are not an essential cell type for controlling bacterial burdens in this acute infection setting, we found higher levels of eosinophils in gut-draining lymph nodes following infection, indicating that eosinophils do respond to Salmonella infection. Our data contribute to the growing evidence that eosinophils are responsive to bacterial stimuli, yet the influence of and requirements for eosinophils during bacterial infection appear to be highly context-dependent.

Interleukin-5 as a pleiotropic cytokine orchestrating airway type 2 inflammation: Effects on and beyond eosinophils

Interleukin (IL)-5 is the key cytokine in the maturation, activation, proliferation, migration and survival of eosinophils, which are key effector cells in many upper and lower airway diseases. Through its effects on eosinophils, IL-5 indirectly contributes to various pathophysiological processes including tissue damage, repair and remodelling. Understanding the importance of IL-5 in eosinophil-associated diseases led to the development of anti-IL-5 therapies, which provide clinical benefits across a range of conditions. However, recent evidence suggests that eosinophil-depletion alone may not account for all of the therapeutic effects of anti-IL-5 therapy and that IL-5 may also contribute to disease independently of its effects on eosinophils. Indeed, evidence from ex vivo studies and targeted therapy in vivo demonstrates that IL-5 and its inhibition affects a much broader range of cells beyond eosinophils, including epithelial cells, plasma cells, mast cells, basophils, neutrophils, type 2 innate lymphoid cells, T regulatory cells and fibroblasts. This review will provide an update on the evidence supporting the breadth of IL-5 biology relevant to disease pathogenesis beyond eosinophil-associated inflammation, where there is a need for additional insight, and the clinical implications of a more central role of IL-5 in type 2 inflammation.

Treatment-Refractory Eosinophilic Esophagitis Successfully Managed with benralizumab: A Case Presentation and literature review

Eosinophilic Esophagitis is a widely-recognized immune-mediated esophagus disease with distinct clinical and histopathological features, exhibiting an increased global incidence. Therapeutic options encompass either dietary measures or pharmacological approaches, including proton pump inhibitors and topical corticosteroids. The use of monoclonal antibodies is currently under comprehensive evaluation, with a plethora of ongoing clinical trials designed to determine their clinical efficacy. The present case report demonstrates an exceptional case of refractory Eosinophilic Esophagitis, unresponsive to conventional treatment, achieving both clinical and histopathological remission subsequent to initiation of benralizumab treatment. Concurrently, our case underscores the necessity for continued research in the field of monoclonal antibodies for their use as a future treatment approach against Eosinophilic Esophagitis.

Pediatric eosinophilic gastritis treated with benralizumab: A case report

We report one of the first cases of eosinophilic gastritis (EoG) in a child under 12 years treated with benralizumab. At 7 years, our patient was started on benralizumab after failing to respond to various combinations of high-dose omeprazole, milk elimination diet, oral viscous budesonide, and oral systemic steroids. He had a complete depletion of gastrointestinal tissue eosinophils with improved symptoms but had symptomatic flares with tapering of background therapy. However, after 4 years on benralizumab he became symptomatic again. Benralizumab may be a viable option for EoG refractory to systemic steroids but only as a short-term adjunct therapy. More robust studies with long-term data are needed, especially in this younger population.

Biologic therapy in rare eosinophil-associated disorders: remaining questions and translational research opportunities

Rare eosinophil-associated disorders (EADs), including hypereosinophilic syndrome, eosinophilic granulomatosis with polyangiitis, and eosinophilic gastrointestinal disorders, are a heterogeneous group of conditions characterized by blood and/or tissue hypereosinophilia and eosinophil-related clinical manifestations. Although the recent availability of biologic therapies that directly and indirectly target eosinophils has the potential to dramatically improve treatment options for all EADs, clinical trials addressing their safety and efficacy in rare EADs have been relatively few. Consequently, patient access to therapy is limited for many biologics, and the establishment of evidence-based treatment guidelines has been extremely difficult. In this regard, multicenter retrospective collaborative studies focusing on disease manifestations and treatment responses in rare EADs have provided invaluable data for physicians managing patients with these conditions and helped identify important questions for future translational research. During the Clinical Pre-Meeting Workshop held in association with the July 2023 biennial meeting of the International Eosinophil Society in Hamilton, Ontario, Canada, the successes and limitations of pivotal multicenter retrospective studies in EADs were summarized and unmet needs regarding the establishment of guidelines for use of biologics in rare EADs were discussed. Key topics of interest included (1) clinical outcome measures, (2) minimally invasive biomarkers of disease activity, (3) predictors of response to biologic agents, and (4) long-term safety of eosinophil depletion. Herein, we report a summary of these discussions, presenting a state-of-the-art overview of data currently available for each of these topics, the limitations of the data, and avenues for future data generation through implementation of multidisciplinary and multicenter studies.

Benralizumab does not elicit therapeutic effect in patients with chronic spontaneous urticaria: results from the phase IIb multinational randomized double-blind placebo-controlled ARROYO trial

BACKGROUND

Chronic spontaneous urticaria (CSU) is a relatively common skin disease associated with hives and angio-oedema. Eosinophils play a role in CSU pathogenesis. Benralizumab, an anti-interleukin-5 receptor-α monoclonal antibody, has been shown to induce nearly complete depletion of eosinophils.

OBJECTIVES

To determine the clinical efficacy and safety of benralizumab in patients with CSU who were symptomatic despite H1 antihistamine treatment.

METHODS

The 24-week, randomized, double-blind, placebo-controlled, phase IIb portion of the ARROYO trial enrolled adult patients with CSU who were currently on H1 antihistamine treatment. Patients were randomized to one of five treatment groups according to benralizumab dose and regimen for a 24-week treatment period. The primary endpoint was change from baseline in Itch Severity Score (ISS)7 at week 12. The key secondary endpoint was change from baseline in Urticaria Activity Score (UAS)7 at week 12. Additional secondary endpoints included other metrics to assess CSU at week 24, blood eosinophil levels, and pharmacokinetics and immunogenicity assessments. Exploratory subgroup analyses were conducted to explore responses according to demographics, clinical features and biomarkers. Safety was assessed in all treatment groups.

RESULTS

Of 155 patients, 59 were randomized to benralizumab 30 mg, 56 to benralizumab 60 mg and 40 to placebo. Baseline and disease characteristics were consistent with what was expected for patients with CSU. There were no significant differences in change from baseline in ISS7 score at week 12 between benralizumab and placebo [benralizumab 30 mg vs. placebo, least-squares mean difference -1.01, 95% confidence interval (CI) -3.28 to 1.26; benralizumab 60 mg vs. placebo, least-squares mean difference -1.79, 95% CI -4.09 to 0.50] nor in change from baseline in UAS7 score at week 12 between benralizumab and placebo (benralizumab 30 mg vs. placebo, P = 0.407; benralizumab 60 mg vs. placebo, P = 0.082). Depletion of blood eosinophil levels was observed at week 24 in patients treated with benralizumab. All other secondary endpoints and exploratory/subgroup analyses indicated no significant differences between benralizumab and placebo. Safety results were consistent with the known profile of benralizumab.

CONCLUSIONS

Although benralizumab resulted in near-complete depletion of blood eosinophils, there was no clinical benefit over placebo.

Eosinophil Depletion with Benralizumab for Eosinophilic Esophagitis

BACKGROUND

Benralizumab is an eosinophil-depleting anti-interleukin-5 receptor α monoclonal antibody. The efficacy and safety of benralizumab in patients with eosinophilic esophagitis are unclear.

METHODS

In a phase 3, multicenter, double-blind, randomized, placebo-controlled trial, we assigned patients 12 to 65 years of age with symptomatic and histologically active eosinophilic esophagitis in a 1:1 ratio to receive subcutaneous benralizumab (30 mg) or placebo every 4 weeks. The two primary efficacy end points were histologic response (≤6 eosinophils per high-power field) and the change from baseline in the score on the Dysphagia Symptom Questionnaire (DSQ; range, 0 to 84, with higher scores indicating more frequent or severe dysphagia) at week 24.

RESULTS

A total of 211 patients underwent randomization: 104 were assigned to receive benralizumab, and 107 were assigned to receive placebo. At week 24, more patients had a histologic response with benralizumab than with placebo (87.4% vs. 6.5%; difference, 80.8 percentage points; 95% confidence interval [CI], 72.9 to 88.8; P<0.001). However, the change from baseline in the DSQ score did not differ significantly between the two groups (difference in least-squares means, 3.0 points; 95% CI, -1.4 to 7.4; P = 0.18). There was no substantial between-group difference in the change from baseline in the Eosinophilic Esophagitis Endoscopic Reference Score, which reflects endoscopic abnormalities. Adverse events were reported in 64.1% of the patients in the benralizumab group and in 61.7% of those in the placebo group. No patients discontinued the trial because of adverse events.

CONCLUSIONS

In this trial involving patients 12 to 65 years of age with eosinophilic esophagitis, a histologic response (≤6 eosinophils per high-power field) occurred in significantly more patients in the benralizumab group than in the placebo group. However, treatment with benralizumab did not result in fewer or less severe dysphagia symptoms than placebo. (Funded by AstraZeneca; MESSINA ClinicalTrials.gov number, NCT04543409.).

Histopathology of Eosinophilic Gastrointestinal Diseases Beyond Eosinophilic Esophagitis

Eosinophilic gastrointestinal diseases (EGID), such as eosinophilic gastritis (EoG), eosinophilic enteritis, and eosinophilic colitis (EoC), are chronic inflammatory conditions characterized by persistent gastrointestinal symptoms and elevated levels of activated eosinophils in the gastrointestinal tract. EoG and eosinophilic duodenitis (EoD) are strongly associated with food allergen triggers and TH2 inflammation, whereas EoC shows minimal transcriptomic overlap with other EGIDs. The level of expression of certain genes associated with TH2 immune response is associated with certain histopathologic findings of EoG, EoD, and EoC. Current immune therapy for EoG depletes tissue eosinophilia with persistence of other histopathologic features of disease.

Pharmacologic Management of Non-Eosinophilic Esophagitis Eosinophilic Gastrointestinal Diseases

Data for pharmacologic treatments for non-eosinophilic esophagitis (EoE) eosinophilic gastrointestinal diseases (EGIDs) are limited. Nevertheless, because of the increasing understanding of EGID pathogenesis, a number of medications are used to treat EGIDs, though all are currently off-label. Initial therapy generally starts with corticosteroids, and "topical" delivery is preferred over systemic due to long-term side effects. A number of other small molecules could potentially be used, ranging from allergy medications to immunosuppressants. Biologics are also being used and investigated for EGIDs and represent promising targeted therapies. Multiple therapeutic targets have also been identified, many of which overlap with EoE targets.

Pharmacologic Management of Eosinophilic Esophagitis

Proton pump inhibitors (PPIs), swallowed topical corticosteroids (STSs), and dupilumab are highly effective therapies for the treatment of eosinophilic esophagitis. Shared decision-making informs the choice of therapy and factors such as ease of use, safety, cost, and efficacy should be addressed. PPIs are the most common medication utilized early in the disease course; however, for nonresponders, STSs are an excellent alternative. Dupilumab is unlikely to replace PPIs or STSs as first-line therapy, except in highly specific circumstances. Identification of novel biologic pathways and the development of small molecules may lead to a wider range of treatment options in the future.

World Health Organization and International Consensus Classification of eosinophilic disorders: 2024 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of non-hematologic (secondary or reactive) and hematologic (primary or clonal) disorders with the potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 109/L, and may be associated with tissue damage. After the exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of various tests. They include morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, molecular testing and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2022 World Health Organization and International Consensus Classification endorse a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions" (MLN-eo-TK), and the MPN subtype, "chronic eosinophilic leukemia" (CEL). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., <1.5 × 109/L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Pemigatinib was recently approved for patients with relapsed or refractory FGFR1-rearranged neoplasms. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, is approved by the U.S Food and Drug Administration for patients with idiopathic HES. Cytotoxic chemotherapy agents, and hematopoietic stem cell transplantation have been used for aggressive forms of HES and CEL, with outcomes reported for limited numbers of patients. Targeted therapies such as the IL-5 receptor antibody benralizumab, IL-5 monoclonal antibody depemokimab, and various tyrosine kinase inhibitors for MLN-eo-TK, are under active investigation.

Clinical and Therapeutic Intervention of Hypereosinophilia in the Era of Molecular Diagnosis

Hypereosinophilia (HE) presents with an elevated peripheral eosinophilic count of >1.5 × 109/L and is composed of a broad spectrum of secondary non-hematologic disorders and a minority of primary hematologic processes with heterogenous clinical presentations, ranging from mild symptoms to potentially lethal outcome secondary to end-organ damage. Following the introduction of advanced molecular diagnostics (genomic studies, RNA sequencing, and targeted gene mutation profile, etc.) in the last 1-2 decades, there have been deep insights into the etiology and molecular mechanisms involved in the development of HE. The classification of HE has been updated and refined following to the discovery of clinically novel markers and targets in the 2022 WHO classification and ICOG-EO 2021 Working Conference on Eosinophil Disorder and Syndromes. However, the diagnosis and management of HE is challenging given its heterogeneity and variable clinical outcome. It is critical to have a diagnostic algorithm for accurate subclassification of HE and hypereosinophilic syndrome (HES) (e.g., reactive, familial, idiopathic, myeloid/lymphoid neoplasm, organ restricted, or with unknown significance) and to follow established treatment guidelines for patients based on its clinical findings and risk stratification.

[Clinical characteristics of 267 children with eosinophilic gastrointestinal disease: a multicenter study]

OBJECTIVES

To explore the clinical manifestations, endoscopic findings, histopathological changes, treatment, and prognosis of eosinophilic gastrointestinal disease (EGID) in children, with the aim of enhancing awareness among pediatricians about this condition.

METHODS

Data of 267 children with EGID were prospectively collected from January 2019 to July 2022 at Jiangxi Children's Hospital, Hunan Children's Hospital, and Henan Children's Hospital. The age of onset, symptoms, physical signs, laboratory examination results, endoscopic findings, histopathological changes, and treatment outcomes were observed.

RESULTS

Among the 267 children with EGID, the majority had mild (164 cases, 61.4%) or moderate (96 cases, 35.6%) clinical severity. The disease occurred at any age, with a higher prevalence observed in school-age children (178 cases). The main symptoms in infants were vomiting and hematemesis, while in toddlers, vomiting and bloody stools were prominent. Abdominal pain and vomiting were the primary symptoms in preschool and school-age children. Nearly half (49.4%) of the affected children showed elevated platelet counts on hematological examination, but there was no significant difference in platelet counts among children with mild, moderate, and severe EGID (P>0.05). Endoscopic findings in EGID children did not reveal significant specificity, and histopathological examination showed no specific structural damage. Among them, 85.0% (227 cases) received acid suppression therapy, 34.5% (92 cases) practiced dietary avoidance, 20.9% (56 cases) received anti-allergic medication, and a small proportion (24 cases, 9.0%) were treated with prednisone. Clinical symptoms were relieved in all patients after treatment, but three cases with peptic ulcers experienced recurrence after drug discontinuation.

CONCLUSIONS

Mild and moderate EGID are more common in children, with no specific endoscopic findings. Dietary avoidance, acid suppression therapy, and anti-allergic medication are the main treatment methods. The prognosis of EGID is generally favorable in children.

Successful Introduction of Benralizumab for Eosinophilic Ascites

Eosinophilic ascites is a rare disorder, reported in both adult and pediatric patients, characterized by high eosinophil counts in the peritoneal fluid. Eosinophilic ascites appears as a manifestation of various diseases such as parasitic and fungal infections, malignancy, and hypereosinophilic syndrome. It also represents an uncommon manifestation of eosinophilic gastroenteritis, usually treated with corticosteroids. We present the case of a 16-year-old woman with abdominal distention related to abundant ascites. Further work-up concluded that it was eosinophilic gastroenteritis complicated with eosinophilic ascites. The patient was on oral steroids for three weeks, but various abdominal relapses were observed, leading to the introduction of benralizumab, as a steroid-sparing therapy with a favorable outcome.

Vectorized Human Antibody-Mediated Anti-Eosinophil Gene Therapy

Chronic hypereosinophilia, defined as persistent elevated blood levels of eosinophils ≥1,500/μL, is associated with tissue infiltration of eosinophils and consequent organ damage by eosinophil release of toxic mediators. The current therapies for chronic hypereosinophilia have limited success, require repetitive administration, and are associated with a variety of adverse effects. As a novel approach to treat chronic hypereosinophilia, we hypothesized that adeno-associated virus (AAV)-mediated delivery of an anti-human eosinophil antibody would provide one-time therapy that would mediate persistent suppression of blood eosinophil levels. To assess this hypothesis, we first generated a human monoclonal antibody (mAb) directed against Siglec8, a sialic-acid binding immunoglobulin-like lectin, expressed at high levels on the cell surface of human eosinophils. Transgenic mice with a human immunoglobulin repertoire were immunized with human Siglec8 protein or DNA encoding human Siglec8. Based on target binding assessments, the 08C07 mAb was chosen for further study. The human variable regions of 08C07 were joined to the human Ig constant region, creating H08C07 (hAntiEos), a fully human anti-human eosinophil mAb. Using the gene sequence of hAntiEos, we created AAVrh.10hAntiEos, an AAVrh.10-based vector expressing the heavy and light chains of H08C07. Intravenous administration of AAVrh.10hAntiEos (1011 genome copies or gc) to C57Bl/6 mice resulted in persistent elevated serum levels of hAntiEos. In vivo gene therapy generated hAntiEos bound to recombinant human Siglec8 protein in a dose-dependent manner and to human eosinophils, mediated apoptosis of human eosinophils, and antibody-dependent cellular cytotoxicity activity against human eosinophils. Consistent with these data, administration of AAVrh.10hAntiEos to human CD34+ transplanted NSG-SGM3 immunodeficient mice suppressed levels of human eosinophils in vivo. AAVrh.10hAntiEos holds the potential to offer therapeutic benefit to patients with chronic hypereosinophilia.

Successful Treatment of Steroid-resistant Eosinophilic Gastrointestinal Disease with Mepolizumab

We experienced a case of treatment-resistant eosinophilic gastrointestinal disease (EGID). The patient, a 46-year-old man, presented with a fever, persistent abdominal pain, and an elevated peripheral eosinophil count. Eosinophil infiltration of the intestinal mucosa was also observed, and EGID was diagnosed. Corticosteroid therapy was initiated, but no improvement was seen. However, after mepolizumab (anti-interleukin 5 antibody) was administered, the patient's disease was controlled. Currently, the indications for mepolizumab are limited to bronchial asthma and paraneoplastic eosinophilic polyangiitis, but the experience herein reported suggests its usefulness in the treatment of EGID.

Current and Novel Therapies for Eosinophilic Gastrointestinal Diseases

Eosinophilic gastrointestinal diseases (EGIDs) are an emerging group of pathological entities characterized by an eosinophil-predominant infiltration of different tracts of the gut in the absence of secondary causes of eosinophilia. According to the specific tract of the gut involved, EGIDs can be classified into eosinophilic esophagitis (EoE), eosinophilic gastritis (EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). The epidemiology of EGIDs is evolving rapidly. EoE, once considered a rare disease, now has an incidence and prevalence of 7.7 new cases per 100,000 inhabitants per years and 34.4 cases per 100,000 inhabitants per year, respectively. Fewer data are available regarding non-EoE EGIDs, whose prevalence are estimated to range between 2.1 and 17.6 in 100,000 individuals, depending on age, sex, and ethnicity. Diagnosis requires the presence of suggestive symptoms, endoscopic biopsies showing abnormal values of eosinophils infiltrating the gut, and exclusion of secondary causes of eosinophilia. EoE typically presents with dysphagia and episodes of food bolus impactions, while EoG, EoN, and EoC may all present with abdominal pain and diarrhea, with or without other non-specific symptoms. In addition, although different EGIDs are currently classified as different entities, there may be overlap between different diseases in the same patient. Despite EGIDs being relatively novel pathological entities, the research on possible treatments is rapidly growing. In this regard, several randomized controlled trials are currently ongoing to investigate novel molecules, including ad-hoc steroid formulations, immunosuppressants, and mostly monoclonal antibodies that target the specific molecular mediators of EGIDs. This narrative review provides an up-to-date overview of available and investigational drugs for different EGIDs.

Stem cell factor inhibition reduces Th2 inflammation and cellular infiltration in a mouse model of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a T helper (Th)2-mediated inflammatory disorder characterized endoscopically by eosinophilic infiltration leading to fibrosis of the esophagus. Stem cell factor (SCF), a multifunctional cytokine, is upregulated in several allergic diseases, including in patients with EoE. Mast cells and eosinophils express c-kit, the cell surface receptor for SCF, and have been found to play an important role in EoE. Therefore, we investigated whether blocking SCF represents a potential therapeutic approach for EoE. Esophageal inflammation was induced in mice using peanut allergen. In mice with experimental EoE, we found that SCF was upregulated in the esophageal tissue. In EoE mice injected with a polyclonal antibody specific for SCF, we observed a decrease in both mast cells and eosinophils by histological and flow cytometric analysis. Furthermore, Th2 cytokines in the esophagus were decreased in anti-SCF treated mice, as were levels of Th2 cytokines from lung-draining and esophageal lymph nodes. Serum levels of peanut-specific immunoglobulin E were reduced following treatment with anti-SCF. In Kitlf/f-Col1-Cre-ERT mice, which have SCF deleted primarily in myofibroblasts that develop in EoE, we observed similar results as the anti-SCF treated animals for inflammatory cell accumulation, cytokines, and histopathology. These results indicate that therapeutic treatments targeting SCF can reduce allergic inflammation in EoE.

Discrepancy between Abdominal Symptoms and Endoscopic Findings in Patients with Gastro-duodenal Eosinophilia: A Case Series

Some patients present gastro-duodenal eosinophilia without abdominal symptoms. Nine cases with gastro-duodenal eosinophilia were seen at the Tohoku University Hospital between January 2011 and June 2022. Seven (78%) patients had a background of allergic or hyper-eosinophilic disease. Esophagogastroduodenoscopy showed erosions (n=6), discoloration (n=4), ulcers (n=3), erythema (n=3), muskmelon-like appearance (n=2), and cracks (n=1). Two cases were asymptomatic with eosinophilic gastroenteritis (EGE)-like endoscopic findings, and two were symptomatic with normal endoscopic findings. The discrepancy between the abdominal symptoms and esophagogastroduodenoscopy findings suggests that clinicians should assess patients for background allergic disease, regardless of abdominal symptoms.

The minichromosome maintenance complex drives esophageal basal zone hyperplasia

Eosinophilic esophagitis (EoE) is a chronic gastrointestinal disorder characterized by food antigen-driven eosinophilic inflammation and hyperproliferation of esophageal mucosa. By utilizing a large-scale, proteomic screen of esophageal biopsies, we aimed to uncover molecular drivers of the disease. Proteomic analysis by liquid chromatography-tandem mass spectrometry identified 402 differentially expressed proteins (DEPs) that correlated with the EoE transcriptome. Immune cell-related proteins were among the most highly upregulated DEPs in EoE compared with controls, whereas proteins linked to epithelial differentiation were primarily downregulated. Notably, in the inflamed esophageal tissue, all 6 subunits of the minichromosome maintenance (MCM) complex, a DNA helicase essential for genomic DNA replication, were significantly upregulated at the gene and protein levels. Furthermore, treating esophageal epithelial cells with a known inhibitor of the MCM complex (ciprofloxacin) blocked esophageal epithelial proliferation. In a murine model of EoE driven by overexpression of IL-13, ciprofloxacin treatment decreased basal zone thickness and reduced dilated intercellular spaces by blocking the transition of epithelial cells through the S-phase of the cell cycle. Collectively, a broad-spectrum proteomic screen has identified the involvement of the MCM complex in EoE and has highlighted MCM inhibitors as potential therapeutic agents for the disease.

Do General Pathologists Assess Gastric and Duodenal Eosinophilia?

CONTEXT.—

Eosinophilic diseases of the gastrointestinal tract (EGIDs), eosinophilic gastritis (EoG), and eosinophilic duodenitis (EoD) are rarely suspected clinically and infrequently detected by pathologists.

OBJECTIVE.—

To determine whether histories of allergic or eosinophilic disorders and requests to rule out EoG and EoD affect pathologists' awareness of eosinophils in gastrointestinal biopsies.

DESIGN.—

Thirty-one community-based pathologists were given 16 sets of biopsies from gastric and duodenal mucosa with elevated eosinophils, Helicobacter pylori gastritis, atrophic gastritis, normal stomach and duodenum, lymphocytosis, and celiac disease. Participants were assigned to 3 groups: group A did not receive histories of allergic or eosinophilic conditions; group B received similar histories plus a clue of possible allergic or eosinophilic conditions; and group C received the same histories as B and was asked to rule out EoG/EoD. A list of gastric and duodenal diagnoses and a space for comments were provided. Results were analyzed descriptively.

RESULTS.—

Pathologists correctly diagnosed most noneosinophilic gastrointestinal disorders, indicating competence in gastrointestinal pathology. With respect to EoG and EoD, pathologists in group C performed significantly better that those in groups A and B. The combined odds ratio with 95% CI was 12.34 (2.87-53.04), P < .001, for A versus C and 4.02 (1.60-10.09), P < .02, for B versus C.

CONCLUSIONS.—

Most pathologists neither reported gastric/duodenal eosinophilia nor diagnosed EoG/EoD, even when provided histories of eosinophilic disorders. Requests to rule out EoG/EoD resulted in only 4 of 11 participants evaluating and counting eosinophils in some cases. Simple evidence-based histopathologic criteria are needed before pathologists can be expected to consider and diagnose EGIDs.

Benralizumab for eosinophilic gastritis: a single-site, randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

In eosinophilic gastrointestinal diseases, the role of eosinophils in disease pathogenesis and the effect of eosinophil depletion on patient outcomes are unclear. Benralizumab, an eosinophil-depleting monoclonal antibody that targets the interleukin-5 receptor α, might eliminate gastric tissue eosinophils and improve outcomes in eosinophilic gastritis. We aimed to assess the efficacy and safety of benralizumab in patients with eosinophilic gastritis.

METHODS

We conducted a single-site, randomised, double-blind, placebo-controlled, phase 2 trial at Cincinnati Children's Hospital Medical Center (Cincinnati, OH, USA). Individuals aged 12-60 years with symptomatic, histologically active eosinophilic gastritis (peak gastric eosinophil count ≥30 eosinophils per high-power field [eos/hpf] in at least five hpfs) and blood eosinophilia (>500 eosinophils per μL [eos/μL]) were randomly assigned (1:1, block size of four) to benralizumab 30 mg or placebo, stratified by the use of glucocorticoids for gastric disease. Investigators, study staff, and study participants were masked to treatment assignment; statisticians were unmasked when analysing data. Treatments were administered subcutaneously once every 4 weeks for a 12-week double-blind period (three total injections). The primary endpoint was the proportion of patients who achieved histological remission (peak gastric eosinophil count <30 eos/hpf) at week 12. Key secondary endpoints were the changes from baseline to week 12 in peak gastric eosinophil count, blood eosinophil count, eosinophilic gastritis histology (total, inflammatory, and structural feature scores), Eosinophilic Gastritis Endoscopic Reference System (EG-REFS) score, and patient-reported outcome symptom measures (Severity of Dyspepsia Assessment [SODA] and Patient-Reported Outcome Measurement Information System [PROMIS] short-form questionnaire). After the 12-week double-blind period, patients were eligible for entry into two open-label extension (OLE) periods up to week 88, in which all patients received benralizumab. Efficacy was analysed in the intention-to-treat (ITT) population and safety was assessed in all patients who received at least one dose of study drug. The trial was registered on ClinicalTrials.gov, NCT03473977, and is completed.

FINDINGS

Between April 23, 2018, and Jan 13, 2020, 34 patients were screened, and 26 were subsequently randomly assigned to benralizumab (n=13) or placebo (n=13) and included in the ITT and safety populations (mean age 19·5 years [SD 7·3]; 19 [73%] male patients and seven [27%] female patients). At week 12, ten (77% [95% CI 50 to 92]) of 13 patients who received benralizumab and one (8% [1 to 33]) of 13 who received placebo achieved histological remission (difference 69 percentage points [95% CI 32 to 85]; p=0·0010). Changes from baseline to week 12 were significantly greater in the benralizumab group versus the placebo group for peak gastric eosinophil counts (mean -137 eos/hpf [95% CI -186 to -88] vs -38 eos/hpf [-94 to 18]; p=0·0080), eosinophilic gastritis histology total score (mean -0·31 [-0·42 to -0·20] vs -0·02 [-0·16 to 0·12]; p=0·0016), histology inflammatory score (mean -0·46 [-0·60 to -0·31] vs -0·04 [-0·22 to 0·13]; p=0·0006), and blood eosinophil counts (median -1060 eos/μL [IQR -1740 to -830] vs -160 eos/μL [-710 to 120]; p=0·0044). Changes were not significantly different between the groups for eosinophilic gastritis histology structural score (mean -0·07 [95% CI -0·19 to 0·05] vs 0·03 [-0·09 to 0·15]; p=0·23), EG-REFS score (mean -1·0 [-2·3 to 0·3] vs -0·5 [-2·0 to 1·0]; p=0·62), or in patient-reported outcomes (SODA and PROMIS). During the double-blind period, treatment-emergent adverse events occurred in 11 (85%) of 13 patients in the benralizumab group and six (46%) of 13 in the placebo group; the most common treatment-emergent adverse events were headache (six [46%] vs two [15%] patients), nausea (three [23%] vs two [15%]), and vomiting (two [15%] vs three [23%]). There were no treatment-related deaths. Two patients had serious adverse events (dizziness and rhabdomyolysis in one patient; aspiration in one patient) during the OLE periods, which were considered unrelated to study treatment.

INTERPRETATION

Benralizumab treatment induced histological remission, as defined by absence of tissue eosinophilia, in most patients with eosinophilic gastritis. However, the persistence of histological, endoscopic, and other features of the disease suggest a co-existing, eosinophil-independent pathogenic mechanism and the need for broader targeting of type 2 immunity.

FUNDING

AstraZeneca and the Division of Intramural Research (National Institute of Allergy and Infectious Diseases, US National Institutes of Health).

Biologics and Hypereosinophilic Syndromes: Knowledge Gaps and Controversies

Hypereosinophilic syndromes (HES) are a heterogeneous group of disorders defined by blood and/or tissue hypereosinophilia and clinical manifestations attributable to the eosinophilia. Although various clinical subtypes of HES have been described, the general approach to therapy in all subtypes has focused on the reduction of blood and tissue eosinophilia to improve symptoms and halt disease progression. Until recently, this typically involved the use of corticosteroids and/or other immunosuppressive or cytotoxic drugs with significant toxicity. Whereas imatinib, the first targeted therapy approved for treatment of HES, has dramatically changed the prognosis of patients with primary (myeloid) forms of HES, it is ineffective in patients with other HES subtypes. For these nonmyeloid patients with HES, the development of eosinophil-targeting biologics (most notably, mepolizumab, the first biologic approved for the treatment of HES) has been transformative. Nevertheless, important issues remain with respect to the efficacy and safety of these biologics in the treatment of the varied subtypes of HES. Moreover, with the increasing number of commercially available biologics with direct or indirect effects on eosinophils, questions related to the choice of initial biologic, potential reasons for biologic failure, and treatment options in the setting of incomplete response are becoming increasingly common.

Non-esophageal eosinophilic gastrointestinal diseases: a narrative review

Eosinophilic gastrointestinal disorders are a group of rare diseases characterized by the infiltration of eosinophils in the gastrointestinal wall in a greater amount than in homeostatic conditions. 'Non-esophageal eosinophilic gastrointestinal disorders' is the umbrella term for all eosinophilic gastrointestinal disorders outside of the well known eosinophilic esophagitis. This includes eosinophilic gastritis, eosinophilic enteritis and eosinophilic colitis. The clinical presentation is atypical and not very different for the three disorders. The depth of infiltration has a bigger influence on the presenting symptoms than the disease location. Although the frequency of diagnosis and research in this subject is increasing over time, non-esophageal eosinophilic disorders are rare and high quality evidence is limited to date. In this narrative review, we provide an overview of the latest insights in the pathophysiology, diagnostic approach and available treatment options. Transcriptome studies have found the pathogenesis to be T helper type 2 driven. Various laboratory findings can be used to trigger raised suspicion and investigation with endoscopy. As the endoscopic appearance of the mucosa is normal in most cases, multiple biopsies in each segment are needed to quantify the amount of eosinophils in the tissue. Eosinophilic cut-offs for diagnosis are a controversial topic and a consensus is still lacking. A recently developed tissue based diagnostic platform which measures differentially expressed genes might be available in the future to classify patients with intermediate eosinophilic tissue levels under the cut-off. For the treatment, corticosteroids are still the cornerstone of treatment but promising research suggests a role of biologicals, such as Lirentelimab (anti-siglec 8) in particular.

The Role of Benralizumab in Eosinophilic Immune Dysfunctions: A Case Report-Based Literature Review

In the past years, the knowledge of eosinophils playing a primary pathophysiologic role in several associated conditions has led to the development of biologics targeting therapies aiming at normalizing the immune response, reducing chronic inflammation, and preventing tissue damage. To better illustrate the potential relationship between different eosinophilic immune dysfunctions and the effects of biological therapies in this scenario, here, we present a case of a 63-year-old male first referred to our department in 2018 with a diagnosis of asthma, polyposis, and rhinosinusitis and presenting a suspicion of nonsteroidal anti-inflammatory drugs' allergy. He also had a past medical history of eosinophilic gastroenteritis/duodenitis (eosinophilia counts >50 cells/high-power field HPF). The use of multiple courses of corticosteroid therapy failed to completely control these conditions. In October 2019, after starting benralizumab (an antibody directed against the alpha chain of the IL-5 cytokine receptor) as add-on treatment for severe eosinophilic asthma, important clinical improvements were reported both on the respiratory (no asthma exacerbations) and gastrointestinal systems (eosinophilia count 0 cells/HPF). Patients' quality of life also increased. Since June 2020, systemic corticosteroid therapy was reduced without worsening of gastrointestinal symptoms or eosinophilic inflammation. This case warns of the importance of early recognition and appropriate individualized treatment of eosinophilic immune dysfunctions and suggests the conduction of further larger studies on the use of benralizumab in gastrointestinal syndromes aiming at better understanding its relying mechanisms of action in the intestinal mucosa.

The role of biologics in pediatric food allergy and eosinophilic gastrointestinal disorders

Continuing insight into the molecular mechanisms of atopic disorders has enabled the development of biologics to precisely target these diseases. Food allergy (FA) and eosinophilic gastrointestinal disorders (EGIDs) are driven by similar inflammatory molecular mechanisms and exist along the same atopic disease spectrum. Therefore, many of the same biologics are being investigated to target key drivers of mechanisms shared across the disease states. The enormous potential of biologics for the treatment of FA and EGIDs is highlighted by the significant increases in the number of ongoing clinical trials (more than 30) evaluating their use in these disease states, as well as by the recent US Food and Drug Administration approval of dupilumab for the treatment of eosinophilic esophagitis. Here we discuss past and current research into the use of biologics in FA and EGIDs and their potential role in improving treatment options in the future, with the need to have biologics widely clinically available.

Dupilumab Leads to Clinical Improvements including the Acquisition of Tolerance to Causative Foods in Non-Eosinophilic Esophagitis Eosinophilic Gastrointestinal Disorders

A recent report showed that most pediatric cases of non-eosinophilic esophagitis (EoE) eosinophilic gastrointestinal disorders (EGIDs) (non-EoE EGIDs) are persistent and severe compared with those of EoE, thus requiring further effective therapeutic approaches. In this study, we present the first case based on a systematic search of non-EoE EGID for which tolerance to causative foods and histological and symptomatic improvements were achieved following dupilumab administration, after elimination diets and omalizumab and mepolizumab treatments. Driven by this case, we investigated the efficacies of biological treatments in non-EoE EGID cases based on the patient studied herein, and other patients identified in the conducted systematic review. Seven articles, including five different biologics, were reviewed. Both clinical efficacies and impact differences among the targeted molecules are demonstrated in this study. Our findings show that dupilumab may affect mechanisms that can suppress symptoms induced by offending foods that are different from those induced by other biologics as identified in the conducted systematic review. Additional studies are required to address the unmet needs of non-EoE EGID treatments.

Current state of biologics in treating eosinophilic esophagitis

OBJECTIVE

Eosinophilic esophagitis (EoE) is a chronic, allergen-mediated, eosinophil-predominant, type 2 inflammatory disease that progresses to fibrostenosis of the esophagus if left untreated. This review focuses on biologics therapy in EoE.

DATA SOURCES

Manuscripts on EoE treatments are identified on PubMed.

STUDY SELECTIONS

Original research, randomized controlled trials, retrospective studies, meta-analyses, case series, and case reports of high relevance are selected and reviewed.

RESULTS

Biologics have been used as investigational therapies for EoE in clinical studies over the years, based on earlier work that identified key cytokines and mediators of eosinophilic inflammation and, more recently, type 2 inflammation that underlie EoE pathogenesis. Dupilumab, a monoclonal antibody that targets the interleukin (IL)-4Rα chain, thereby interfering with IL-4 and IL-13 binding with the receptor, was recently approved by the Food and Drug Administration for EoE. Dupilumab improved clinical symptoms, endoscopic scores, histologic inflammation, and esophageal distensibility. Several clinical trials that target key cytokines such as IL-5, IL-13, and thymic stromal lymphopoietin in EoE are still ongoing.

CONCLUSION

Topical corticosteroid, proton pump inhibitor therapy, elimination diet, and dilation are widely accepted treatment modalities for EoE. Dupilumab is the first Food and Drug Administration-approved therapy for EoE. Other studies evaluating biologics that target eosinophils, key cytokines, and inflammatory pathways in EoE are ongoing. Treatment algorithms are needed to position EoE therapies as they emerge.

Living without eosinophils: evidence from mouse and man

The enduring view of eosinophils, as immune effector cells whose primary function is host defence against infection by helminths and other microbial pathogens, sets the stage for a fundamental question regarding the safety of therapeutic eosinophil depletion. If eosinophils are significantly reduced or altogether depleted in an effort to alleviate the negative effects of tissue eosinophilia and eosinophilic inflammation in conditions such as asthma, COPD, chronic rhinosinusitis with nasal polyps, eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome, would these patients become susceptible to infection or another illness? Development of mouse models in which the eosinophil lineage has been ablated, observations in patients naturally lacking eosinophils and data from studies of eosinophil-depleting medical therapies indicate that the absence of eosinophils is not detrimental to health. The evidence available to date, as presented in this review, supports the conclusion that even if certain homeostatic roles for the eosinophil may be demonstrable in controlled animal models and human in vitro settings, the evolution of the human species appears to have provided sufficient immune redundancy such that one may be hale and hearty without eosinophils.

Urine eosinophil-derived neurotoxin: A potential marker of activity in select eosinophilic disorders

BACKGROUND

Biomarkers of eosinophilic disease activity, especially in the context of novel therapies that reduce blood eosinophil counts, are an unmet need. Absolute eosinophil count (AEC) does not accurately reflect tissue eosinophilia or eosinophil activation. Therefore, the aims of this study were to compare the reliability of plasma and urine eosinophil major basic protein 1, eosinophil cationic protein, eosinophil-derived neurotoxin (EDN), and eosinophil peroxidase measurement and to evaluate the usefulness of eosinophil granule protein (EGP) measurement for the assessment of disease activity in patients with eosinophil-associated diseases treated with mepolizumab, benralizumab, or dexpramipexole.

METHODS

Eosinophil granule protein concentrations were measured in serum, plasma, and urine from healthy volunteers and patients with hypereosinophilic syndrome (HES), eosinophilic granulomatosis with polyangiitis (EGPA), and eosinophilic asthma using a multiplex assay.

RESULTS

Urine EGP concentrations remained stable, whereas serum and plasma EGP concentrations increased significantly with delayed processing. Plasma (p) EDN, but not urine (u) EDN, concentration correlated with AEC and negatively correlated with prednisone dose. Both pEDN and uEDN decreased significantly following treatment of HES patients with benralizumab and EGPA patients with mepolizumab. uEDN appeared to increase with clinical relapse in both patient groups.

CONCLUSIONS

Measurement of EGP in urine is noninvasive and unaffected by cellular lysis. Although plasma and urine EDN concentrations showed a similar pattern following benralizumab and mepolizumab treatment, the lack of correlation between AEC or prednisone dose and uEDN concentrations suggests that measurement of uEDN may provide a potential biomarker of disease activity in patients with HES and EGPA.

Biologics in eosinophilic gastrointestinal diseases

Eosinophilic gastrointestinal diseases are a constellation of conditions categorized by the location of eosinophilic infiltration in the gastrointestinal tract. Symptoms vary based on location of eosinophils and age of the patient. There are no approved medications at the current time with individuals using off-label steroids or dietary therapy. Translational research has identified potential pathways to target in the treatment of eosinophilic esophagitis (EoE), gastritis (EoG), and enteritis (EoN), including type 2 pathways, mast cells, and eosinophils. Preliminary studies found cendakimab (anti-interleukin [IL]-13) and dupilumab (anti-IL-4 receptor alpha) to have an effect on eosinophil count and symptoms with dupilumab recently approved. In addition, mepolizumab (anti-IL-5), reslizumab (anti-IL-5), and lirentelimab (anti-Siglec 8) were found to have reduction in eosinophils without reduction of symptoms. For EoG and EoN, both benralizumab (anti-IL-5 receptor) and lirentelimab were found to have histologic and symptom improvement. There are no agents studied for eosinophilic colitis. Results of ongoing phase 3 trials in EoE and EoG/EoN are also anticipated.

Food Allergy and Eosinophilic Gastrointestinal Diseases-The Next 10 Years

The first report of food allergy desensitization was in 1908, at least a few years before the first published description of a diagnostic test for food allergy. It has taken almost 100 years for food allergy to move from passive management of avoidance to a more proactive approach including prevention and treatment. In parallel, this has been matched by recognition of eosinophil gastrointestinal diseases, which were first described in the 1980s (although eosinophilic esophagitis was itself described in 1978). As we celebrate 10 years of The Journal of Allergy and Clinical Immunology: In Practice, we take the opportunity to look into the future and speculate how our practice may develop over the next decade.

The new indications for biologicals in type 2 diseases: perspectives

PURPOSE OF REVIEW

To provide a literature review of what is on the market and under study for some diseases treated with drugs targeting type 2 (T2) inflammation.

RECENT FINDINGS

Literature data have shown that drugs targeting type 2 inflammation are effective in asthma and nasal polyposis, conditions for which they are on the market, and have promising expectations in the case of eosinophilic esophagitis, especially using anti-IL-5/IL-5 receptor and IL-4 receptor antibodies, while concerning eosinophilic granulomatosis with polyangitis (EGPA), mepolizumab (MEP) was approved by FDA and EMA as a drug for the treatment of this condition because of the promising results obtained in trials and in real life.

SUMMARY

The use of these drugs is certainly an important achievement in the treatment of complex diseases such as those mentioned above, which are too often orphaned from innovative treatments and limited to the use of immunosuppressants and systemic corticosteroid for their control.

Eosinophilic Gastrointestinal Diseases Beyond the Esophagus: An Evolving Field and Nomenclature

The eosinophilic gastrointestinal diseases (EGIDs) are a group of chronic, immune-mediated gastrointestinal (GI) diseases characterized by GI symptoms and pathologic eosinophilic infiltration of specific areas within the GI tract in the absence of secondary causes of eosinophilia. The non-eosinophilic esophagitis EGIDs remain understudied and likely underdiagnosed, owing in part to the lack of clarity in the terminology previously used to describe these diseases. The newly established EGID nomenclature framework includes a first-tier description of the specific location of GI tract involvement and a second-tier description with more granular characterizations of disease involvement. EGIDs can involve any segment or layer of the GI tract, so patients can present with a wide array of common, nonspecific GI symptoms. Diagnosing EGIDs requires endoscopic evaluation and biopsies showing increased eosinophilic tissue infiltration in the correct clinical context after ruling out other causes of eosinophilia. Although the pathogenesis is not yet fully understood, EGIDs are likely allergic conditions triggered by food antigen exposure. Most patients are currently treated with corticosteroids, but investigations of other pharmacologic and dietary therapies are ongoing. This article highlights the recently updated EGID nomenclature and summarizes the current understanding of the diagnosis, pathogenesis, and treatment of EGIDs.