Mepolizumab in refractory eosinophilic asthma

Subsets of Eosinophils in Asthma, a Challenge for Precise Treatment

The existence of eosinophils was documented histopathologically in the first half of the 19th century. However, the term “eosinophils” was first used by Paul Ehrlich in 1878. Since their discovery and description, their existence has been associated with asthma, allergies, and antihelminthic immunity. Eosinophils may also be responsible for various possible tissue pathologies in many eosinophil-associated diseases. Since the beginning of the 21st century, the understanding of the nature of this cell population has undergone a fundamental reassessment, and in 2010, J. J. Lee proposed the concept of “LIAR” (Local Immunity And/or Remodeling/Repair), underlining the extensive immunoregulatory functions of eosinophils in the context of health and disease. It soon became apparent that mature eosinophils (in line with previous morphological studies) are not structurally, functionally, or immunologically homogeneous cell populations. On the contrary, these cells form subtypes characterized by their further development, immunophenotype, sensitivity to growth factors, localization, role and fate in tissues, and contribution to the pathogenesis of various diseases, including asthma. The eosinophil subsets were recently characterized as resident (rEos) and inflammatory (iEos) eosinophils. During the last 20 years, the biological therapy of eosinophil diseases, including asthma, has been significantly revolutionized. Treatment management has been improved through the enhancement of treatment effectiveness and a decrease in the adverse events associated with the formerly ultimately used systemic corticosteroids. However, as we observed from real-life data, the global treatment efficacy is still far from optimal. A fundamental condition, “sine qua non”, for correct treatment management is a thorough evaluation of the inflammatory phenotype of the disease. We believe that a better understanding of eosinophils would lead to more precise diagnostics and classification of asthma subtypes, which could further improve treatment outcomes. The currently validated asthma biomarkers (eosinophil count, production of NO in exhaled breath, and IgE synthesis) are insufficient to unveil super-responders among all severe asthma patients and thus give only a blurred picture of the adepts for treatment. We propose an emerging approach consisting of a more precise characterization of pathogenic eosinophils in terms of the definition of their functional status or subset affiliation by flow cytometry. We believe that the effort to find new eosinophil-associated biomarkers and their rational use in treatment algorithms may ameliorate the response rate to biological therapy in patients with severe asthma.

Should we apply a treatable traits approach to asthma care?

OBJECTIVE

To explore the evidence for adopting a "treatable traits" approach to asthma management.

DATA SOURCES

PubMed, Medline, and Google Scholar.

STUDY SELECTIONS

The above-mentioned databases were searched for randomized, controlled phase III or IV trials of adults containing the word "asthma" in the title published in the previous 10 years and for all articles containing the title words "treatable AND trait(s)," "asthma AND biomarker(s) OR smoking OR obesity OR laryngeal OR management" published within the previous 5 years. Articles were excluded if they were not published in English. Our search identified 257 articles for consideration. We also manually searched the reference lists of studies identified and searched the websites of the British Thoracic Society, European Respiratory Society, National Institute for Health and Care Excellence, and Global Initiative for Asthma for specific guidance related to asthma management.

RESULTS

The "treatable traits" are described within 3 domains of pulmonary, extrapulmonary, or behavioral and lifestyle traits. We consider whether treatment should be targeted toward these traits where they are present in asthma patients, based on currently available evidence, rather than increasing treatment in response to symptoms in line with current step-up, step-down asthma management guidelines.

CONCLUSION

We advocate that a treatable traits approach should be applied more broadly to the assessment and management of inadequately controlled asthma, rather than a step-up, step-down approach based on patient symptoms. This approach should be focused on the 2 treatable pulmonary traits of T_H2 inflammation and airflow obstruction along with smoking cessation, in the first instance.

Controversies in Allergy: Choosing a Biologic for Patients with Severe Asthma

The availability of a range of new biological treatments targeting type-2 inflammation has provided new opportunities for patients with more severe asthma. Treatment has a bigger effect on exacerbations than day-to-day symptoms, and efficacy increases with increasing intensity of type-2 airway inflammation as reflected by the blood eosinophil count and fractional exhaled nitric oxide. The similarity of the clinical effects and target populations coupled with the absence of direct head-to-head comparative data makes it difficult to choose the right biologic for a given patient. In this review, we summarize the key efficacy data from phase 3 trials; discuss indirect comparisons; review clinical and laboratory variables that may be associated with a differential response to treatment; outline practical considerations that might be important to individual patients; and suggest an algorithm for choosing the most appropriate biologic to start with and the first choice to switch to.

Balancing the needs of the many and the few: where next for adult asthma guidelines?

Asthma differs from many other chronic conditions in that most key management decisions are made in non-specialist settings, such as general practitioner surgeries and accident and emergency departments. Diagnosis in primary care relies on recognition of a characteristic pattern of symptoms and the occurrence of asthma attacks, sometimes supplemented by basic lung function tests. Ongoing management is guided by the assessment of symptoms and simple lung function measures of airflow obstruction, with little attempt made to personalise management. This approach is flawed because the inadequate specificity of symptoms, as well as the low sensitivity of variable airflow obstruction, means that a diagnosis of asthma is often difficult to exclude with confidence. Moreover, even if diagnosed correctly, dissociation between inflammation, airflow obstruction, and symptoms means that a generalised stepwise approach to managing asthma on the basis of symptoms is unlikely to be successful in a substantial proportion of patients. As a result, effective treatments are used inefficiently, and outcomes are often worse than they could be. Rather than use of either a population-based or personalised approach for the diagnosis and management of asthma, we recommend a new combined approach, in which treatment decisions are driven by objective assessment of key treatable mechanistic traits.

Eosinophil Development, Disease Involvement, and Therapeutic Suppression

Human eosinophils have characteristic morphologic features, including a bilobed nucleus and cytoplasmic granules filled with cytotoxic and immunoregulatory proteins that are packaged in a specific manner. Eosinophil production in the bone marrow is exquisitely regulated by timely expression of a repertoire of transcription factors that work together via collaborative and hierarchical interactions to direct eosinophil development. In addition, proper granule formation, which occurs in a spatially organized manner, is an intrinsic checkpoint that must be passed for proper eosinophil production to occur. In eosinophil-associated disorders, eosinophils and their progenitors can be recruited in large numbers into tissues where they can induce proinflammatory organ damage in response to local signals. Eosinophils are terminally differentiated and do not proliferate once they leave the bone marrow. The cytokine IL-5 specifically enhances eosinophil production and, along with other mediators, promotes eosinophil activation. Indeed, eosinophil depletion with anti-IL-5 or anti-IL-5Rα is now proven to be clinically beneficial for several eosinophilic disorders, most notably severe asthma, and several therapeutics targeting eosinophil viability and production are now in development. Significant progress has been made in our understanding of eosinophil development and the consequences of tissue eosinophilia. Future research efforts focused on basic eosinophil immunobiology and translational efforts to assist in the diagnosis, treatment selection, and resolution of eosinophil-associated disorders will likely be informative and clinically helpful.

Predictors of enhanced response with benralizumab for patients with severe asthma: pooled analysis of the SIROCCO and CALIMA studies

BACKGROUND

Benralizumab is an anti-eosinophilic, anti-interleukin-5 receptor α monoclonal antibody that has been shown to significantly reduce asthma exacerbations and improve lung function for patients with severe, uncontrolled asthma. We further explored the efficacy of benralizumab for patients with different baseline blood eosinophil thresholds and exacerbation histories.

METHODS

This study is a pooled analysis of the results from the randomised, double-blind, placebo-controlled SIROCCO (NCT01928771) and CALIMA (NCT01914757) phase 3 studies. In these studies, patients with severe, uncontrolled asthma were randomly assigned (1:1:1) to receive subcutaneous benralizumab 30 mg, either every 4 weeks or every 8 weeks (with first three doses given every 4 weeks), or placebo every 4 weeks. The primary endpoint was annual exacerbation rate (AER) ratio versus placebo, analysed by baseline eosinophil counts (≥0, ≥150, ≥300, or ≥450 cells per μL) and by number of exacerbations (two vs three or more) during the year before enrolment. The analyses were done in accordance with the intention-to-treat principle.

FINDINGS

Of 2295 patients, 756 received benralizumab every 4 weeks, 762 received benralizumab every 8 weeks, and 777 patients received placebo. AER among patients with baseline blood eosinophil counts of at least 0 cells per μL was 1·16 (95% CI 1·05-1·28) in patients who received placebo versus 0·75 (0·66-0·84) in patients who received benralizumab every 8 weeks (rate ratio 0·64, 0·55-0·75; p<0·0001). In patients who received benralizumab every 4 weeks who had eosinophil counts of 0 or more cells per μL, AER was 0·73 (0·65-0·82); rate ratio versus placebo was 0·63 (0·54-0·74; p<0·0001). The extent to which exacerbation rates were reduced increased with increasing blood eosinophil thresholds and with greater exacerbation history in patients in the 4-weekly and 8-weekly benralizumab groups. Greater improvements in AER were seen with benralizumab compared with placebo for patients with a combination of high blood eosinophil thresholds and a history of more frequent exacerbations.

INTERPRETATION

These results will help to guide clinicians when they are deciding whether to use benralizumab to treat patients with severe, uncontrolled, eosinophilic asthma.

FUNDING

AstraZeneca.

Transcription Factors in Eosinophil Development and As Therapeutic Targets

Dynamic gene expression is a major regulatory mechanism that directs hematopoietic cell fate and differentiation, including eosinophil lineage commitment and eosinophil differentiation. Though GATA-1 is well established as a critical transcription factor (TF) for eosinophil development, delineating the transcriptional networks that regulate eosinophil development at homeostasis and in inflammatory states is not complete. Yet, recent advances in molecular experimental tools using purified eosinophil developmental stages have led to identifying new regulators of gene expression during eosinophil development. Herein, recent studies that have provided new insight into the mechanisms of gene regulation during eosinophil lineage commitment and eosinophil differentiation are reviewed. A model is described wherein distinct classes of TFs work together via collaborative and hierarchical interactions to direct eosinophil development. In addition, the therapeutic potential for targeting TFs to regulate eosinophil production is discussed. Understanding how specific signals direct distinct patterns of gene expression required for the specialized functions of eosinophils will likely lead to new targets for therapeutic intervention.

An early innate response underlies severe influenza-induced exacerbations of asthma in a novel steroid-insensitive and anti-IL-5-responsive mouse model

BACKGROUND

Acute worsening of asthma symptoms (exacerbation) is predominantly triggered by respiratory viruses, with influenza causing the most severe exacerbations. The lack of an adequate animal model hampers mechanistic insight and the development of new therapeutics.

AIM

We developed and characterized a robust, consistent, and reproducible mouse model of severe exacerbation of chronic allergic asthma.

METHODS

Chronic allergic airway inflammation was induced following a house dust mite (HDM) sensitization protocol. HDM-sensitized mice and controls were infected with influenza virus A/X31 H3N2 and either or not treated with inhaled fluticasone propionate (FP), systemic corticosteroids (Pred), or anti-IL-5. Mice were killed at different time points after infection: Cellular accumulation and cytokines levels in the airways, PenH as a measure of airway hyper-responsiveness (AHR), and lung histology and viral replication were assessed.

RESULTS

Infection with low-dose A/X31 H3N2 led to prolonged deterioration of lung function, aggravated mucus production, peri-vascular, peri-bronchial, and allergic inflammation that was unresponsive to inhaled corticosteroids, but responsive to systemic corticosteroids. The exacerbation was preceded at 14 h after virus exposure by a marked innate, but no Th2 and Th1 response subsequently followed by enhanced numbers of eosinophils, neutrophils, dendritic, and T cells into the lung lumen, parenchyma, and draining lymph nodes in HDM-sensitized mice. Anti-IL-5 treatment attenuated eosinophils and prevented the X31-induced exacerbation.

CONCLUSIONS

Together, these findings indicate that an early innate response that involves eosinophils underlies the exacerbation. This model recapitulates all major features of severe asthma exacerbations and can serve to discern driving mechanisms and promote the development of novel therapeutics.

Omalizumab Is Equally Effective in Persistent Allergic Oral Corticosteroid-Dependent Asthma Caused by Either Seasonal or Perennial Allergens: A Pilot Study

Omalizumab is marketed for chronic severe asthma patients who are allergic to perennial allergens. Our purpose was to investigate whether omalizumab is also effective in persistent severe asthma due to seasonal allergens. Thirty patients with oral corticosteroid-dependent asthma were treated with Omalizumab according to the dosing table. For each patient with asthma due to seasonal allergens, we recruited the next two consecutive patients with asthma due to perennial allergens. The dose of oral methyl prednisolone (MP) was tapered at a rate of 2 mg every two weeks after the start of treatment with omalizumab depending on tolerance. At each monthly visit, a forced spirometry and fractional exhaled nitric oxide (FeNO) measurement were performed and the accumulated monthly MP dose was calculated. At entry, there were no differences between groups in terms of gender, body mass index or obesity, year exacerbation rate, monthly dose of MP, FeNO and blood immunoglobuline E (IgE) values, or spirometry (perennial: FVC: 76%; FEV₁: 62%; seasonal: FVC: 79%; FEV₁: 70%). The follow-up lasted 76 weeks. One patient in each group was considered a non-responder. Spirometry did not worsen in either group. There was a significant intragroup reduction in annual exacerbation rate and MP consumption but no differences were detected in the intergroup comparison. Omalizumab offered the same clinical benefits in the two cohorts regardless of whether the asthma was caused by a seasonal or a perennial allergen. These results strongly suggest that allergens are the trigger in chronic asthma but that it is the persistent exposure to IgE that causes the chronicity.

Changing Paradigms in the Treatment of Severe Asthma: The Role of Biologic Therapies

Cytokine antagonists are monoclonal antibodies that offer new treatment options for refractory asthma but will also increase complexity because they are effective only for patients with certain asthma subtypes that remain to be more clearly defined. The clinical and inflammatory heterogeneity within refractory asthma makes it difficult to manage the disease and to determine which, if any, biologic therapy is suitable for a specific patient. The purpose of this article is to provide a data-driven discussion to clarify the use of biologic therapies in patients with refractory asthma. We first discuss the epidemiology and pathophysiology of refractory asthma. We then interpret current evidence for biomarkers of eosinophilic or type 2-high asthma so that clinicians can determine potential treatments for patients based on knowledge of their effectiveness in specific asthma phenotypes. We then assess clinical data on the efficacy, safety, and mechanisms of action of approved and pipeline biologic therapies. We conclude by discussing the potential of phenotyping or endotyping refractory asthma and how biologic therapies can play a role in treating patients with refractory asthma.

Eosinophil resistance to glucocorticoid-induced apoptosis is mediated by the transcription factor NFIL3

The mainstay of asthma therapy, glucocorticoids (GCs) exert their therapeutic effects through the inhibition of inflammatory signaling and induction of eosinophil apoptosis. However, laboratory and clinical observations of GC-resistant asthma suggest that GCs' effects on eosinophil viability may depend on the state of eosinophil activation. In the present study we demonstrate that eosinophils stimulated with IL-5 show impaired pro-apoptotic response to GCs. We sought to determine the contribution of GC-mediated transactivating (TA) and transrepressing (TR) pathways in modulation of activated eosinophils' response to GC by comparing their response to the selective GC receptor (GR) agonist Compound A (CpdA) devoid of TA activity to that upon treatment with Dexamethasone (Dex). IL-5-activated eosinophils showed contrasting responses to CpdA and Dex, as IL-5-treated eosinophils showed no increase in apoptosis compared to cells treated with Dex alone, while CpdA elicited an apoptotic response regardless of IL-5 stimulation. Proteomic analysis revealed that both Nuclear Factor IL-3 (NFIL3) and Map Kinase Phosphatase 1 (MKP1) were inducible by IL-5 and enhanced by Dex; however, CpdA had no effect on NFIL3 and MKP1 expression. We found that inhibiting NFIL3 with specific siRNA or by blocking the IL-5-inducible Pim-1 kinase abrogated the protective effect of IL-5 on Dex-induced apoptosis, indicating crosstalk between IL-5 anti-apoptotic pathways and GR-mediated TA signaling occurring via the NFIL3 molecule. Collectively, these results indicate that (1) GCs' TA pathway may support eosinophil viability in IL-5-stimulated cells through synergistic upregulation of NFIL3; and (2) functional inhibition of IL-5 signaling (anti-Pim1) or the use of selective GR agonists that don't upregulate NFIL3 may be effective strategies for the restoring pro-apoptotic effect of GCs on IL-5-activated eosinophils.

[New drugs for severe asthma]

Asthma is a very frequent disease with complex and heterogenous immunological and clinical features. Daily inhaled steroids are the cornerstone of the current therapeutics sometimes associated with long-acting β2-agonist. This controller treatment is effective and allows to control asthma symptoms for the vast majority of the patients. Severe asthma is characterized by a poor level of control of symptoms, with recurrent exacerbations or a chronic airflow limitation despite an optimal management. Severe asthma remains a difficult diagnosis but we have now studies proving the clinical efficacy or promising data about monoclonal antibodies targeting IgE, IL-5, IL-4 or IL-13. Most of these monoclonal antibodies target the Th2 type eosinophilic inflammation without any treatment against non-eosinophilic or Th1 inflammation. Last, it will be essential to assess accurately the cost effectiveness of these expensive treatments, to identify and to qualify the target population for each molecule and to assess its financial impact for the community.

Severe asthma: anti-IgE or anti-IL-5?

Severe asthma is a discrete clinical entity characterised by recurrent exacerbations, reduced quality of life and poor asthma control as ordinary treatment regimens remain inadequate. Difficulty in managing severe asthma derives partly from the multiple existing phenotypes and our inability to recognise them. Though the exact pathogenetic pathway of severe allergic asthma remains unclear, it is known that numerous inflammatory cells and cytokines are involved, and eosinophils represent a key inflammatory cell mediator. Anti-IgE (omalizumab) and anti-IL-5 (mepolizumab) antibodies are biological agents that interfere in different steps of the Th2 inflammatory cascade and are licensed in severe asthma. Both exhibit a favourable clinical outcome as they reduce exacerbation rate and improve asthma control and quality of life, while mepolizumab also induces an oral steroid sparing effect. Nevertheless, it is still questionable which agent is more suitable in the management of severe allergic asthma since no comparable studies have been conducted. Omalizumab's established effectiveness in clinical practice over a long period is complemented by a beneficial effect on airway remodelling process mediated mainly through its impact on eosinophils and other parameters strongly related to eosinophilic inflammation. However, it is possible that mepolizumab through nearly depleting eosinophils could have a similar effect on airway remodelling. Moreover, to date, markers indicative of the patient population responding to each treatment are unavailable although baseline eosinophils and exacerbation rate in the previous year demonstrate a predictive value regarding anti-IL-5 therapy effectiveness. On the other hand, a better therapeutic response for omalizumab has been observed when low forced expiratory volume in 1 sec, high-dose inhaled corticosteroids and increased IgE concentrations are present. Consequently, conclusions are not yet safe to be drawn based on existing knowledge, and additional research is necessary to unravel the remaining issues for the severe asthmatic population.

Benralizumab, an anti-interleukin-5 receptor α monoclonal antibody, as add-on treatment for patients with severe, uncontrolled, eosinophilic asthma (CALIMA): a randomised, double-blind, placebo-controlled phase 3 trial

BACKGROUND

Benralizumab is a humanised, afucosylated, anti-interleukin-5 receptor α monoclonal antibody that induces direct, rapid, and nearly complete depletion of eosinophils. We aimed to assess the efficacy and safety of benralizumab as add-on therapy for patients with severe, uncontrolled asthma and elevated blood eosinophil counts.

METHODS

In this randomised, double-blind, parallel-group, placebo-controlled, phase 3 study (CALIMA) undertaken at 303 sites in 11 countries, we enrolled patients aged 12-75 years with severe asthma uncontrolled by medium-dosage to high-dosage inhaled corticosteroids plus long-acting β₂-agonists (ICS plus LABA) and a history of two or more exacerbations in the previous year. Patients were randomly assigned (1:1:1) to receive 56 weeks of benralizumab 30 mg every 4 weeks (Q4W), benralizumab 30 mg every 8 weeks (Q8W; first three doses 4 weeks apart), or placebo (all subcutaneous injection). Patients were stratified (2:1) by baseline blood eosinophil counts 300 cells per μL or greater and less than 300 cells per μL, respectively. Patients and study centre staff were masked to treatment allocation. The primary endpoint was annual exacerbation rate ratio versus placebo for patients receiving high-dosage ICS plus LABA with baseline blood eosinophils 300 cells per μL or greater (intention-to-treat analysis). Key secondary endpoints were pre-bronchodilator forced expiratory volume in 1 s (FEV₁) and total asthma symptom score. This study is registered with ClinicalTrials.gov, number NCT01914757.

FINDINGS

Between Aug 21, 2013, and March 16, 2015, 2505 patients were enrolled, of whom 1306 patients were randomised; 425 patients were randomly assigned to and received benralizumab 30 mg Q4W, 441 to benralizumab 30 mg Q8W, and 440 to placebo. 728 patients were included in the primary analysis population. Benralizumab resulted in significantly lower annual exacerbation rates with the Q4W regimen (rate 0·60 [95% CI 0·48-0·74], rate ratio 0·64 [95% CI 0·49-0·85], p=0·0018, n=241) and Q8W regimen (rate 0·66 [95% CI 0·54-0·82], rate ratio 0·72 [95% CI 0·54-0·95], p=0·0188, n=239) compared with placebo (rate 0·93 [95% CI 0·77-1·12], n=248). Benralizumab also significantly improved pre-bronchodilator FEV₁ (Q4W and Q8W) and total asthma symptom score (Q8W only) in these patients. The most common adverse events were nasopharyngitis (90 [21%] in the Q4W group, 79 [18%] in the Q8W group, and 92 [21%] in the placebo group) and worsening asthma (61 [14%] in the Q4W group, 47 [11%] in the Q8W group, and 68 [15%] in the group).

INTERPRETATION

Benralizumab significantly reduced annual exacerbation rates and was generally well tolerated for patients with severe, uncontrolled asthma with blood eosinophils 300 cells per μL or greater. Our data further refine the patient population likely to receive the greatest benefit from benralizumab treatment.

FUNDING

AstraZeneca and Kyowa Hakko Kirin.

Benralizumab: a unique IL-5 inhibitor for severe asthma

The presence of eosinophilic inflammation is a characteristic feature of chronic and acute inflammation in asthma. An estimated 5%–10% of the 300 million people worldwide who suffer from asthma have a severe form. Patients with eosinophilic airway inflammation represent approximately 40%–60% of this severe asthmatic population. This form of asthma is often uncontrolled, marked by refractoriness to standard therapy, and shows persistent airway eosinophilia despite glucocorticoid therapy. This paper reviews personalized novel therapies, more specifically benralizumab, a humanized anti-IL-5Rα antibody, while also being the first to provide an algorithm for potential candidates who may benefit from anti-IL-5Rα therapy.

Novel strategies for the treatment of asthma

Novel treatment strategies are currently emerging for patients with inadequately controlled asthma despite good adherence and trigger avoidance. These strategies serve primarily to reduce or completely avoid long-term oral corticosteroid therapy. A number of these options have already been implemented in practice or will soon be authorized for the treatment of asthma, while others still need to prove their clinical practicability, safety and efficacy. The present article provides an overview of the broad spectrum of novel inhaled, oral, systemic, and invasive treatment strategies for asthma.

Cluster analysis and characterization of response to mepolizumab. A step closer to personalized medicine for patients with severe asthma

RATIONALE

Detailed characterization of asthma phenotypes is essential for identification of responder populations to allow directed personalized medical intervention.

OBJECTIVES

The aim of this study was to identify distinctive patient characteristics within subgroups of a well-characterized severe asthma population at risk for exacerbations and to determine the treatment response within each subgroup.

METHODS

A supervised cluster analysis with recursive partitioning approach was applied to data from the Dose Ranging Efficacy And safety with Mepolizumab (DREAM) study to identify characteristics that maximized the differences across subgroups. Exacerbation rate ratios were calculated for each cluster comparing mepolizumab versus placebo.

MEASUREMENTS AND MAIN RESULTS

Three predictors were identified in four primary clusters: blood eosinophils, airway reversibility, and body mass index. The reduction in exacerbations was significantly greater in patients who received mepolizumab (clusters 2, 3, and 4) with raised eosinophils (responder population). Cluster 2 with low airway reversibility (mean, 11%) had a 53% reduction in exacerbations. These patients more frequently reported sinusitis and nasal polyposis. Those with higher airway reversibility (mean, 28%) were further split by body mass index. The nonobese versus obese (clusters 3 and 4) had a 35 and 67% reduction in exacerbations, respectively. Cluster 4 also had patients with more comorbidities, including hypertension, weight gain, and anxiety.

CONCLUSIONS

Using supervised cluster analysis helped identify specific patient characteristics related to disease and therapeutic response. Patients with eosinophilic inflammation received significant therapeutic benefit with mepolizumab, and responses differed within clusters. Clinical trial registered with www.clinicaltrials.gov (NCT01000506).

A randomized trial of benralizumab, an antiinterleukin 5 receptor α monoclonal antibody, after acute asthma

BACKGROUND

Patients with frequent asthma exacerbations resulting in emergency department (ED) visits are at increased risk for future exacerbations. We examined the ability of 1 dose of benralizumab, an investigational antiinterleukin 5 receptor α monoclonal antibody, to reduce recurrence after acute asthma exacerbations.

METHODS

In this randomized, double-blind, placebo-controlled study, eligible subjects presented to the ED with an asthma exacerbation, had partial response to treatment, and greater than or equal to 1 additional exacerbation within the previous year. Subjects received 1 intravenous infusion of placebo (n = 38) or benralizumab (0.3 mg/kg, n = 36 or 1.0 mg/kg, n = 36) added to outpatient management. The primary outcome was the proportion of subjects with greater than or equal to 1 exacerbation at 12 weeks in placebo vs the combined benralizumab groups. Other outcomes included the time-weighted rate of exacerbations at week 12, adverse events, blood eosinophil counts, asthma symptom changes, and health care resource utilization.

RESULTS

The proportion of subjects with greater than or equal to 1 asthma exacerbation at 12 weeks was not different between placebo and the combined benralizumab groups (38.9% vs 33.3%; P = .67). However, compared with placebo, benralizumab reduced asthma exacerbation rates by 49% (3.59 vs 1.82; P = .01) and exacerbations resulting in hospitalization by 60% (1.62 vs 0.65; P = .02) in the combined groups. Benralizumab reduced blood eosinophil counts but did not affect other outcomes, while demonstrating an acceptable safety profile.

CONCLUSIONS

When added to usual care, 1 dose of benralizumab reduced the rate and severity of exacerbations experienced over 12 weeks by subjects who presented to the ED with acute asthma.

Targeting interleukins to treat severe asthma

Severe asthma is thought to be a heterogeneous disease with different phenotypes predicated primarily on the nature of the inflammatory cell infiltrate and response to corticosteroid therapy. This group of patients often has refractory disease with an associated increase in morbidity and mortality, and there remains a need for better therapies for severe asthmatics. Inflammatory changes in asthma are driven by immune mechanisms, within which interleukins play an integral role. Interleukins are cell-signaling cytokines that are produced by a variety of cells, predominantly T cells. Knowledge about their actions has improved the understanding of the pathogenesis of asthma and provided potential targets for novel therapies. To date, this has not translated into clinical use. However, there are ongoing clinical trials that use monoclonal antibodies for various interleukins, some of which have shown to be promising in Phase II studies.

[Pulmonary allergic reactions]

Allergic diseases of the lungs may affect the airways, the pulmonary parenchyma and the pulmonary vessels. The most relevant representatives are allergic asthma, hypersensitivity pneumonitis, bronchopulmonary aspergillosis and the Churg-Strauss syndrome. The type of allergic reaction and the pathophysiological consequences vary considerably between these entities. New drugs target specific mechanisms based on new insights into the pathogenetic processes of the underlying disease.

Complex airway disease: an approach to assessment and management

Research into new treatments for airway disease focuses on severe disease because morbidity, mortality, and health-care costs are substantial and the unmet need is greatest. One reason why outcomes are poor in these patients could be that the clinical expression of disease is heterogeneous and difficult to classify. As a result, guideline-based management algorithms fail. Additionally, difficulties with disease classification and misconceptions about the relation between different aspects of severe airway disease have hindered new drug development. A potential solution is to use a new approach to assess severe airway disease, which moves the diagnostic focus from categorisation of patients to identification and characterisation of the main drivers of disease. This approach will help rather than hinder identification of clinically important phenotypes of disease and will facilitate the development of new phenotype-specific treatment options.

Mepolizumab treatment for asthma

INTRODUCTION

Five percent of asthmatics have severe symptoms despite high doses of inhaled (ICS) or additional oral corticosteroids (OCS): these patients have high morbidity, risk for asthma death, and account for half of asthma healthcare spending. A subgroup (20 - 40%) of these has persistent airway eosinophilia and frequent exacerbations. Mepolizumab is a humanized monoclonal antibody that blocks binding of the key cytokine implicated specifically in eosinophil maturation and survival, interleukin-5, to its receptor.

AREAS COVERED

Pharmacology, Phase I/IIa and Phase II/III studies of mepolizumab for asthma. Mepolizumab depleted blood and sputum eosinophils and partially reduced airway and bone marrow eosinophils. It also reduced airway remodeling. In unselected patients with moderate/severe asthma there was no clinically significant effect on lung function, but a trend to reduced exacerbation rates. When patients were selected for persistent sputum eosinophilia despite high-dose ICS/OCS, and frequent exacerbations, mepolizumab reduced exacerbations by 50%.

EXPERT OPINION

Mepolizumab can reduce exacerbation rates in the severe asthma cohort who have eosinophilic airway inflammation despite corticosteroid treatment. This may be 30% of severe asthmatics and represents a new and important treatment option. Further studies need to confirm efficacy and indications for asthma (and other eosinophilic airway disease), and to examine clinical consequences of reducing remodeling.

Mepolizumab for severe eosinophilic asthma (DREAM): a multicentre, double-blind, placebo-controlled trial

BACKGROUND

Some patients with severe asthma have recurrent asthma exacerbations associated with eosinophilic airway inflammation. Early studies suggest that inhibition of eosinophilic airway inflammation with mepolizumab-a monoclonal antibody against interleukin 5-is associated with a reduced risk of exacerbations. We aimed to establish efficacy, safety, and patient characteristics associated with the response to mepolizumab.

METHODS

We undertook a multicentre, double-blind, placebo-controlled trial at 81 centres in 13 countries between Nov 9, 2009, and Dec 5, 2011. Eligible patients were aged 12-74 years, had a history of recurrent severe asthma exacerbations, and had signs of eosinophilic inflammation. They were randomly assigned (in a 1:1:1:1 ratio) to receive one of three doses of intravenous mepolizumab (75 mg, 250 mg, or 750 mg) or matched placebo (100 mL 0·9% NaCl) with a central telephone-based system and computer-generated randomly permuted block schedule stratified by whether treatment with oral corticosteroids was required. Patients received 13 infusions at 4-week intervals. The primary outcome was the rate of clinically significant asthma exacerbations, which were defined as validated episodes of acute asthma requiring treatment with oral corticosteroids, admission, or a visit to an emergency department. Patients, clinicians, and data analysts were masked to treatment assignment. Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01000506.

FINDINGS

621 patients were randomised: 159 were assigned to placebo, 154 to 75 mg mepolizumab, 152 to 250 mg mepolizumab, and 156 to 750 mg mepolizumab. 776 exacerbations were deemed to be clinically significant. The rate of clinically significant exacerbations was 2·40 per patient per year in the placebo group, 1·24 in the 75 mg mepolizumab group (48% reduction, 95% CI 31-61%; p<0·0001), 1·46 in the 250 mg mepolizumab group (39% reduction, 19-54%; p=0·0005), and 1·15 in the 750 mg mepolizumab group (52% reduction, 36-64%; p<0·0001). Three patients died during the study, but the deaths were not deemed to be related to treatment.

INTERPRETATION

Mepolizumab is an effective and well tolerated treatment that reduces the risk of asthma exacerbations in patients with severe eosinophilic asthma.

FUNDING

GlaxoSmithKline.

Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's βc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common βc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

Animal models of asthma: value, limitations and opportunities for alternative approaches

Asthma remains an area of considerable unmet medical need. Few new drugs have made it to the clinic during the past 50 years, with many that perform well in preclinical animal models of asthma, failing in humans owing to lack of safety and efficacy. The failure to translate promising drug candidates from animal models to humans has led to questions about the utility of in vivo studies and to demand for more predictive models and tools based on the latest technologies. Following a workshop with experts from academia and the pharmaceutical industry, we suggest here a disease modelling framework designed to better understand human asthma, and accelerate the development of safe and efficacious new asthma drugs that go beyond symptomatic relief.