Targeting immunoglobulin E in non-atopic asthma: crossing the red line?

IgE-Mediated Activation of Mast Cells and Basophils in Health and Disease

Type 2-mediated immune responses protect the body against environmental threats at barrier surfaces, such as large parasites and environmental toxins, and facilitate the repair of inflammatory tissue damage. However, maladaptive responses to typically nonpathogenic substances, commonly known as allergens, can lead to the development of allergic diseases. Type 2 immunity involves a series of prototype TH2 cytokines (IL-4, IL-5, IL-13) and alarmins (IL-33, TSLP) that promote the generation of adaptive CD4+ helper Type 2 cells and humoral products such as allergen-specific IgE. Mast cells and basophils are integral players in this network, serving as primary effectors of IgE-mediated responses. These cells bind IgE via high-affinity IgE receptors (FcεRI) expressed on their surface and, upon activation by allergens, release a variety of mediators that regulate tissue responses, attract and modulate other inflammatory cells, and contribute to tissue repair. Here, we review the biology and effector mechanisms of these cells, focusing primarily on their role in mediating IgE responses in both physiological and pathological contexts.

The new biologic drugs: Which children with asthma should get what?

Novel biologics (targeted antibody therapies) have revolutionized the management of severe childhood asthma. However, it is important that the right biologic is selected for the right patient, and understanding the evidence base for each biologic is crucial. Currently, four biologics (all monoclonal antibodies) are licensed in the UK for the treatment of children with severe asthma - omalizumab (Xolair), mepolizumab (Nucala), and dupilumab (Dupixent) in children aged 6 years and over; and tezepelumab (Tezspire), only in children aged 12 years and over. Tezepelumab is the only licensed biological that may be beneficial in severe asthma without evidence of Type 2 inflammation. All have a good safety profile but varying degrees of clinical efficacy in children, with wide variation in treatment responsiveness between individual patients. When selecting biologics for severe asthma, it is essential to remember the limitations of the current pediatric evidence. At present, there are no results from randomized, head-to-head trials of biologics in severe asthma. TREAT is an ongoing trial comparing omalizumab to mepolizumab and will be one of the first to provide such evidence. We must be especially aware of the dangers of extrapolating data from adults to children, because the pathophysiology and role of biomarkers may differ significantly from adult asthma. Given the current level of knowledge, even after treatment has been initiated, children should be regularly reviewed to determine the efficacy of treatment, side-effect profile and consideration of when treatment with the biologic should be discontinued.

Controversies and opportunities in severe asthma

PURPOSE OF REVIEW

Despite currently available treatments, many asthma patients remain inadequately controlled, but identifying distinct patient populations (phenotypes/endotypes) may optimize their management. This review discusses some of the controversies and opportunities for improved disease control in severe asthma.

RECENT FINDINGS

Currently approved anti-immunoglobulin E and anti-interleukin 5 biologics, which target specific pathways instead of using a 'one size fits all' strategy, are efficacious and well tolerated therapies for severe asthma. The appropriate use of these biologics, and of those in development (e.g., benralizumab and dupilumab), should be aided by further understanding of asthma phenotypes and endotypes, utilizing appropriate biomarkers.Oral corticosteroids are often added as maintenance therapy for patients with severe uncontrolled asthma, but their use is associated with significant adverse effects and should be considered a last option. The true cost of this therapy, including the cost of morbidities associated with its use, remains to be determined.Severe asthma in pediatrics poses a unique opportunity for possible prevention strategies and the potential for primary prevention. Although several avenues for primary prevention are being explored and are out of the scope of this review, we focus our discussion on the use of omalizumab, which has been recently explored in clinical trials.

SUMMARY

Appropriate use of biologics in severe asthma should be supported by further understanding of biomarkers predicting response to targeted therapy. Because of their association with significant adverse effects, add-on oral corticosteroids should be considered a last treatment option for patients with uncontrolled severe asthma. Finally, severe asthma in pediatrics poses a unique opportunity for potential prevention strategies.

Prospects for new and emerging therapeutics in severe asthma: the role of biologics

INTRODUCTION

Asthma is a common and heterogeneous disease. While current conventional therapies are effective in the majority of the patients, a significant subgroup remain uncontrolled despite these treatments. Different biological agents are currently approved or undergoing development for treatment of asthma, including anti-IgE, anti-interleukin (IL)-5, anti-IL-13, anti-IL-4 and anti-thymic stromal lymphopoietin agents. This review will focus on the currently available evidence regarding the new and emerging biological agents in severe asthma. Areas covered: A non-systematic review of the available English-language literature regarding severe asthma and biological agents was performed. We summarized and discussed the current evidence about the use of new and emerging biological agents in severe asthma. Expert commentary: Because of the heterogeneity of response to therapy in refractory asthma it is of utmost importance to correctly estimate patient outcomes before starting biological therapy to make patient selection more effective. Currently, the decision of which biologic to initiate in patients with uncontrolled severe asthma should be made based on the atopic status, blood eosinophil and total IgE levels, exacerbation history, safety profile, cost, frequency and route of administration.