Clinical Development of Mepolizumab for the Treatment of Severe Eosinophilic Asthma: On the Path to Personalized Medicine

Eosinophil-targeted treatment strategies for long-term outcomes in severe eosinophilic asthma

BACKGROUND

Airway eosinophilic inflammation is a key pathobiologic trait of severe asthma, a complex chronic disease which affects about 5-10% of asthmatic patients worldwide. Therefore, an in-depth knowledge of the immunopathologic mechanisms underlying severe eosinophilic asthma (SEA) is essential to understand the beneficial effects of currently available, eosinophil-targeted anti-asthma treatments, as well as to develop new therapeutic strategies.

AREAS COVERED

This narrative review article aims to provide a concise coverage of the pathophysiology of severe eosinophilic asthma, followed by an updated overview of current and newly emerging therapeutic approaches capable of counteracting airway eosinophilic inflammation. All information reported comes from an extensive literature search conducted on PubMed.

EXPERT OPINION

The recent advances regarding our understanding of the proinflammatory pathways characterizing the various SEA endotypes are allowing to shape effective therapeutic options, driven by the accurate selection of relevant molecular targets. Such successful developments are at the basis of the sustained clinical remission of eosinophilic asthma, which today represents a realistic goal for many severe asthmatic patients.

A real-world study to evaluate effectiveness of mepolizumab in treating severe asthma in Taiwan (REMIT)

BACKGROUND

REMIT is the first real-world study of mepolizumab effectiveness in patients with severe asthma (SA) in Taiwan.

OBJECTIVES

The primary objective evaluated changes in clinically significant exacerbations (CSEs; defined as use of oral corticosteroids (OCS) or emergency department (ED) visits and/or hospitalizations) in the 12 months pre- and post-mepolizumab treatment. Secondary objectives assessed changes in the number of CSEs requiring ED visits/hospitalizations and daily maintenance OCS (mOCS) dosage 12 months pre- and post-mepolizumab treatment. Three- and four-component clinical remissions were analyzed based on OCS-free, exacerbation-free, and asthma control (± stability in lung function).

DESIGN

REMIT was a retrospective, observational, self-controlled study analyzing patients in Taiwan with SA who were newly prescribed subcutaneous mepolizumab 100 mg Q4W.

METHODS

Data were extracted from records of 15 medical centers in Taiwan for patients indexed between November 1, 2018 and October 31, 2020.

RESULTS

A total of 170 patients were included: mean age at index date, 58.7 years; 53.5% female; 100% Chinese; 7.1% with chronic rhinosinusitis with nasal polyps, 1.8% with eosinophilic granulomatosis with polyangiitis, 1.2% with hypereosinophilic syndrome; and 55.7% with blood eosinophil count >300/µL. Pre-treatment, 71.2% had ⩾2 exacerbations, and 28.7% were on mOCS; 75.3% had no prior biologic treatment, and 24.7% had switched from other biologics. Most patients (80.0%) completed ⩾10 mepolizumab doses. Following the first mepolizumab administration (index date), CSEs reduced by 46.0% (rate ratio (RR): 0.545, 95% confidence interval (CI): 0.418-0.710; p < 0.0001) in the 12 months post-index. Exacerbations requiring ED visits/hospitalization reduced by 46.9% (RR: 0.531, 95% CI: 0.349-0.808; p = 0.0031). Median mOCS dose reduced by 100% by end of study and 81.8% of patients discontinued mOCS post-treatment. After 1 year of mepolizumab treatment, 28% and 23% patients achieved three- and four-component clinical remission, respectively.

CONCLUSION

Mepolizumab use in a patient population in Taiwan with SA significantly reduced CSEs and mOCS use in routine clinical practice.

Long-term safety of mepolizumab for up to ∼10 years in patients with severe asthma: open-label extension study

OBJECTIVES

Long-term safety monitoring of mepolizumab is necessary to support real-world use for the treatment of severe asthma. This Long-Term Access Program assessed the safety and benefit:risk of mepolizumab in pediatric, adolescent, and adult patients with severe asthma.

MATERIALS AND METHODS

This was a multicenter, Phase IIIb safety, open-label extension study of multiple prior studies assessing mepolizumab in addition to standard of care (Aug 2015 - Aug 2022). Adults/adolescents (≥12 years of age) received mepolizumab 100 mg subcutaneously (SC) every 4 weeks until mepolizumab was commercialized. Pediatric patients (6-11 years of age) received mepolizumab 40 mg or 100 mg SC (bodyweight <40 or ≥40 kg, respectively) every 4 weeks. Safety was assessed every 4 weeks and benefit:risk every 12 weeks.

RESULTS

Of the 514 patients enrolled, 57% were female and the mean age was 51.1 (standard deviation: 14.9) years; 24 (5%) patients were 6-17 years of age. Total cumulative mepolizumab exposure across all mepolizumab studies included in this analysis was 1500.59 patient-years; median exposure was 2.03 (range, 0.08 to 9.97) years. Overall, 37 (7%) patients experienced on-treatment serious adverse events (SAEs): 34/502 (7%) in the 100 mg SC group and 3/7 (43%) in the 40 mg SC pediatric group. Two patients experienced SAEs considered to be treatment-related by the investigator. Infections were the most common SAEs of special interest (9 [2%] patients). Physician-assessed benefit:risk of mepolizumab supported continued treatment over the study period.

CONCLUSIONS

This long-term safety analysis of mepolizumab was consistent with previous reports, with no emerging safety concerns; most patients had a favorable benefit:risk up to ∼10 years.

CLINICAL TRIAL IDENTIFIER

NCT00244686 (GSK ID 201956).

Therapeutic monoclonal antibodies in allergy: Targeting IgE, cytokine, and alarmin pathways

The etiology of allergy is closely linked to type 2 inflammatory responses ultimately leading to the production of allergen-specific immunoglobulin E (IgE), a key driver of many allergic conditions. At a high level, initial allergen exposure disrupts epithelial integrity, triggering local inflammation via alarmins including IL-25, IL-33, and TSLP, which activate type 2 innate lymphoid cells as well as other immune cells to secrete type 2 cytokines IL-4, IL-5 and IL-13, promoting Th2 cell development and eosinophil recruitment. Th2 cell dependent B cell activation promotes the production of allergen-specific IgE, which stably binds to basophils and mast cells. Rapid degranulation of these cells upon allergen re-exposure leads to allergic symptoms. Recent advances in our understanding of the molecular and cellular mechanisms underlying allergic pathophysiology have significantly shaped the development of therapeutic intervention strategies. In this review, we highlight key therapeutic targets within the allergic cascade with a particular focus on past, current and future treatment approaches using monoclonal antibodies. Specific targeting of alarmins, type 2 cytokines and IgE has shown varying degrees of clinical benefit in different allergic indications including asthma, chronic spontaneous urticaria, atopic dermatitis, chronic rhinosinusitis with nasal polyps, food allergies and eosinophilic esophagitis. While multiple therapeutic antibodies have been approved for clinical use, scientists are still working on ways to improve on current treatment approaches. Here, we provide context to understand therapeutic targeting strategies and their limitations, discussing both knowledge gaps and promising future directions to enhancing clinical efficacy in allergic disease management.

Quantifying corticosteroid burden in chronic rhinosinusitis with nasal polyps: A retrospective US database study

BACKGROUND

Real-world burden data on systemic corticosteroid (SCS) use in chronic rhinosinusitis with nasal polyps (CRSwNP) are limited.

OBJECTIVE

To describe the real-world burden of SCS in CRSwNP.

METHODS

This retrospective cohort study included commercial/Medicare Advantage with Part D health plan members from the Optum Research Database with a first medical claim (index) for CRSwNP (January 2015-July 2020). Primary outcomes/variables included SCS use, health care resource utilization, and costs during the 12-month follow-up period. Outcomes were analyzed overall (N = 21,172) and stratified by baseline comorbid asthma status and sinus surgeries during follow-up.

RESULTS

Overall, 64.7% and 41.0% of patients used all-cause and CRSwNP-related SCS, respectively, and 36.0% had ≥1 oral corticosteroid (OCS) burst (≥20 mg for 3-28 days); SCS use was higher in patients with asthma and those with a NP-related surgery (1, 2, and ≥3) vs without. The mean (SD) all-cause cumulative oral corticosteroid dose was 303.3 (675.0) mg/year and 23.5% had a cumulative annual dose ≥400 mg; these values were higher (P < .001) in patients with vs without comorbid asthma (514.9 [956.1] vs 247.5 [567.0]; 36.9% vs 19.9%). All-cause and CRSwNP health care resource utilization and costs increased with increasing number of surgeries; mean (SD) all-cause total medical costs were $14,472 (38,915), $26,909 (40,800), $29,816 (41,677), and $31,558 (37,143) with 0, 1, 2, and ≥3 surgeries, respectively.

CONCLUSION

These data highlight the significant burden of SCS use in CRSwNP, particularly in patients with comorbid asthma, and suggest a need to reduce SCS exposure.

Single-cell proteomics and transcriptomics capture eosinophil development and identify the role of IL-5 in their lineage transit amplification

The activities, ontogeny, and mechanisms of lineage expansion of eosinophils are less well resolved than those of other immune cells, despite the use of biological therapies targeting the eosinophilia-promoting cytokine interleukin (IL)-5 or its receptor, IL-5Rα. We combined single-cell proteomics and transcriptomics and generated transgenic IL-5Rα reporter mice to revisit eosinophilopoiesis. We reconciled human and murine eosinophilopoiesis and provided extensive cell-surface immunophenotyping and transcriptomes at different stages along the continuum of eosinophil maturation. We used these resources to show that IL-5 promoted eosinophil-lineage expansion via transit amplification, while its deletion or neutralization did not compromise eosinophil maturation. Informed from our resources, we also showed that interferon response factor-8, considered an essential promoter of myelopoiesis, was not intrinsically required for eosinophilopoiesis. This work hence provides resources, methods, and insights for understanding eosinophil ontogeny, the effects of current precision therapeutics, and the regulation of eosinophil development and numbers in health and disease.

Mepolizumab in Patients With Severe Asthma and Comorbidities: 1-Year REALITI-A Analysis

BACKGROUND

Severe asthma is complex; comorbidities may influence disease outcomes.

OBJECTIVE

To assess mepolizumab effectiveness in patients with severe asthma and comorbidities.

METHODS

REALITI-A was a 2-year international, prospective study enrolling adults with asthma newly prescribed mepolizumab (100 mg subcutaneously) at physician's discretion. This post hoc analysis assessed 1-year outcomes stratified by comorbidities at enrollment: chronic rhinosinusitis with nasal polyps (CRSwNP), gastroesophageal reflux disease (GERD), depression/anxiety, and chronic obstructive pulmonary disease (COPD). Outcomes included the rate of clinically significant asthma exacerbations (CSEs; requiring systemic corticosteroids and/or hospital/emergency room admission) between the 12 months pre- and post-mepolizumab treatment and changes from baseline in daily maintenance oral corticosteroid dose (mo 12), Asthma Control Questionnaire-5 score (mo 12) and forced expiratory volume in 1 second (FEV1; mo 9-12).

RESULTS

At enrollment (n = 822), 321 of 822 (39%), 309 of 801 (39%), 203 of 785 (26%), and 81 of 808 (10%) patients had comorbid CRSwNP, GERD, depression/anxiety, and COPD, respectively. Post- versus pre-treatment across all comorbidity subgroups: the rate of CSEs decreased by 63% or more; among 298 (39%) patients on maintenance oral corticosteroids at baseline, median dose decreased by 50% or more; Asthma Control Questionnaire-5 score decreased by 0.63 or more points; FEV1 increased by 74 mL or more. Patients with versus without CRSwNP had the greatest improvements (eg, rate of CSEs decreased by 75%). Patients without GERD, depression/anxiety, or COPD had greater improvements than those with the respective comorbidities, except for FEV1 in patients with COPD.

CONCLUSIONS

Mepolizumab improved disease outcomes in patients with severe asthma irrespective of comorbidities, with additional benefit for patients with CRSwNP.

Safety and Efficacy of Dexpramipexole in Eosinophilic Asthma (EXHALE): A randomized controlled trial

BACKGROUND

There is a need for new and effective oral asthma therapies. Dexpramipexole, an oral eosinophil-lowering drug, has not previously been studied in asthma.

OBJECTIVE

We sought to evaluate the safety and efficacy of dexpramipexole in lowering blood and airway eosinophilia in subjects with eosinophilic asthma.

METHODS

We performed a randomized, double-blind, placebo-controlled proof-of-concept trial in adults with inadequately controlled moderate to severe asthma and blood absolute eosinophil count (AEC) greater than or equal to 300/μL. Subjects were randomly assigned (1:1:1:1) to dexpramipexole 37.5, 75, or 150 mg BID (twice-daily) or placebo. The primary end point was the relative change in AEC from baseline to week 12. Prebronchodilator FEV1 week-12 change from baseline was a key secondary end point. Nasal eosinophil peroxidase was an exploratory end point.

RESULTS

A total of 103 subjects were randomly assigned to dexpramipexole 37.5 mg BID (N = 22), 75 mg BID (N = 26), 150 mg BID (N = 28), or placebo (N = 27). Dexpramipexole significantly reduced placebo-corrected AEC week-12 ratio to baseline, in both the 150-mg BID (ratio, 0.23; 95% CI, 0.12-0.43; P < .0001) and the 75-mg BID (ratio, 0.34; 95% CI, 0.18-0.65; P = .0014) dose groups, corresponding to 77% and 66% reductions, respectively. Dexpramipexole reduced the exploratory end point of nasal eosinophil peroxidase week-12 ratio to baseline in the 150-mg BID (median, 0.11; P = .020) and the 75-mg BID (median, 0.17; P = .021) groups. Placebo-corrected FEV1 increases were observed starting at week 4 (nonsignificant). Dexpramipexole displayed a favorable safety profile.

CONCLUSIONS

Dexpramipexole demonstrated effective eosinophil lowering and was well tolerated. Additional larger clinical trials are needed to understand the clinical efficacy of dexpramipexole in asthma.

Management of eosinophil-associated inflammatory diseases: the importance of a multidisciplinary approach

Elevated eosinophil counts in blood and tissue are a feature of many pathological processes. Eosinophils can migrate and accumulate in a wide variety of tissues and, by infiltrating a target organ, can mediate the development of several inflammatory diseases. The normalization of eosinophilia is a common biomarker of a treatable trait and can also be used as a prognostic and predictive biomarker since it implies a reduction in type 2 inflammation that contributes to disease pathogenesis. Biological therapies targeting this cell type and its proinflammatory mediators have been shown to be effective in the management of a number of eosinophilic diseases, and for this reason they constitute a potential common strategy in the treatment of patients with various multimorbidities that present with type 2 inflammation. Various biological options are available that could be used to simultaneously treat multiple target organs with a single drug, bearing in mind the need to offer personalized treatments under the umbrella of precision medicine in all patients with eosinophil-associated diseases (EADs). In addition to reviewing these issues, we also discuss a series of perspectives addressing the management of EAD patients from a multidisciplinary approach, with the collaboration of health professionals from different specialties who manage the different multimorbidities that frequently occur in these patients. We examine the basic principles of care that this multidisciplinary approach must cover and present a multidisciplinary expert opinion regarding the ideal management of patients with EADs, from diagnosis to therapeutic approach and follow-up.

Diagnosis and Assessment of the Asthmas

Optimizing asthma diagnosis is an essential part of global strategies to reduce the excessive illness burden from asthma. New understanding about how to address the complexity and heterogeneity of the different forms of asthma means that asthma diagnosis now requires a compound diagnostic approach and label. Eliciting the typical symptoms and abnormal physiology of variable airflow limitation permits the recognition of asthma, and the identification of further features, such as eosinophilic or type 2 inflammation, allows a compound diagnostic label of eosinophilic asthma. This conveys key information about future exacerbation risk and likely treatment responsiveness. Treatable traits are a useful way to implement this new approach to diagnosis. Targeted assessment is used to inform a specific treatment plan in a pragmatic and iterative process.

Asthma Management in Adults

Management of asthma in adults has advanced in the past 10 years. Central to these advances has been further clarification of type (T) 2 mechanisms of airway inflammation and utilization of T2 biomarkers, that is, eosinophils and fractional exhaled nitric oxide. In addition, epithelial cells are emerging as significant contributors to inflammation through generation of alarmins to initiate local injury as well as downstream pathways. Five new biologics, mepolizumab, benralizumab, reslizumab, dupilumab, and tezepelumab, were approved to join omalizumab and revolutionize severe asthma treatment. These biologics significantly prevent exacerbations to spare systemic corticosteroids use and their side effects. Guidelines attest to the effectiveness of inhaled corticosteroids/long-acting β-agonists (formoterol) for both maintenance and rescue therapy. Focused updates to the Expert Panel Report addressed limited but specific questions relevant to asthma control. Future guidelines should include phenotype/endotype-directed therapeutics to gain more precision-directed treatment.

Suppression of airway allergic eosinophilia by Hp-TGM, a helminth mimic of TGF-β

Type 2-high asthma is a chronic inflammatory disease of the airways which is increasingly prevalent in countries where helminth parasite infections are rare, and characterized by T helper 2 (Th2)-dependent accumulation of eosinophils in the lungs. Regulatory cytokines such as TGF-β can restrain inflammatory reactions, dampen allergic Th2 responses, and control eosinophil activation. The murine helminth parasite Heligmosomoides polygyrus releases a TGF-β mimic (Hp-TGM) that replicates the biological and functional properties of TGF-β despite bearing no structural similarity to the mammalian protein. Here, we investigated if Hp-TGM could alleviate allergic airway inflammation in mice exposed to Alternaria alternata allergen, house dust mite (HDM) extract or alum-adjuvanted ovalbumin protein (OVA). Intranasal administration of Hp-TGM during Alternaria exposure sharply reduced airway and lung tissue eosinophilia along with bronchoalveolar lavage fluid IL-5 and lung IL-33 cytokine levels at 24 h. The protective effect of Hp-TGM on airway eosinophilia was also obtained in the longer T-cell mediated models of HDM or OVA sensitisation with significant inhibition of eotaxin-1, IL-4 and IL-13 responses depending on the model and time-point. Hp-TGM was also protective when administered parenterally either when given at the time of allergic sensitisation or during airway allergen challenge. This project has taken the first steps in identifying the role of Hp-TGM in allergic asthma and highlighted its ability to control lung inflammation and allergic pathology. Future research will investigate the mode of action of Hp-TGM against airway allergic eosinophilia, and further explore its potential to be developed as a biotherapeutic in allergic asthma.

From DREAM to REALITI-A and beyond: Mepolizumab for the treatment of eosinophil-driven diseases

Effective treatment of inflammatory diseases is often challenging owing to their heterogeneous pathophysiology. Understanding of the underlying disease mechanisms is improving and it is now clear that eosinophils play a complex pathophysiological role in a broad range of type 2 inflammatory diseases. Standard of care for these conditions often still includes oral corticosteroids (OCS) and/or cytotoxic immune therapies, which are associated with debilitating side effects. Selective, biological eosinophil‐reducing agents provide treatment options that improve clinical symptoms associated with eosinophilic inflammation and reduce OCS use. Mepolizumab is a humanized monoclonal antibody that binds to and neutralizes interleukin‐5, the major cytokine involved in eosinophil proliferation, activation, and survival. Mepolizumab is approved for the treatment of severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome. Additionally, the efficacy of add‐on mepolizumab has been observed in patients with severe chronic rhinosinusitis with nasal polyposis and chronic obstructive pulmonary disease with an eosinophilic phenotype. Here, we review the development, approval, and real‐world effectiveness of mepolizumab for the treatment of patients with severe eosinophilic asthma, from the DREAM to REALITI‐A studies, and describe how knowledge from this journey extended to the use of mepolizumab and other biologics across a broad spectrum of eosinophilic diseases.

[Practical guide for the follow-up and management of patients with severe asthma treated with biologics]

The management of severe uncontrolled asthma with biologics is an area of extreme difficulty given the scarcity of information regarding their starting criteria, the variables to be evaluated to determine the efficacy and safety of their management, the cut-off points to determine the timing to change or add another biological and the process to decrease or withdraw steroids. This review incorporates the latest information and makes a proposal based on it.

Phenotyping in acute respiratory distress syndrome: state of the art and clinical implications

PURPOSE OF REVIEW

Decades of research in acute respiratory distress syndrome (ARDS) have led to few interventions that impact clinical outcomes. The pandemic of patients with ARDS due to the novel SARS-CoV-2 infection has stressed the need for more effective therapies in ARDS. Phenotyping may enable successful trials and precision therapeutics in this patient population.

RECENT FINDINGS

Clinical phenotypes that group patients by shared cause, time-course or radiographic presentation are of prognostic value, but their use is limited by misclassification. Physiological phenotypes, including the P/F ratio, ventilatory ratio and dead space fraction, predict poor outcomes but can rapidly change, making them unstable over time. Biologic phenotypes have prognostic value with composite clinical and biomarker sub-phenotypes additionally impacting treatment response but are yet to be prospectively validated.

SUMMARY

Although much progress has been made in ARDS phenotyping, implementation of precision medicine practices will depend on conducting phenotype-aware trials using rapid point of care assays or machine learning algorithms. Omics studies will enhance our understanding of biologic determinants of clinical outcomes in ARDS sub-phenotypes. Whether biologic ARDS sub-phenotypes are specific to this syndrome or rather more broadly identify endotypes of critical illness remains to be determined.

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.

Blood eosinophils in managing preschool wheeze: Lessons learnt from a proof-of-concept trial

BACKGROUND

Management of preschool wheeze is based predominantly on symptom patterns.

OBJECTIVE

To determine whether personalizing therapy using blood eosinophils or airway bacterial infection results in fewer attacks compared with standard care.

METHODS

A proof-of-concept, randomized trial to investigate whether the prescription of inhaled corticosteroids (ICS) guided by blood eosinophils, or targeted antibiotics for airway bacterial infection, results in fewer unscheduled healthcare visits (UHCVs) compared with standard care. Children aged 1-5 years with ≥2 wheeze attacks in the previous year were categorized as episodic viral wheeze (EVW) or multiple trigger wheeze (MTW). The intervention group was prescribed ICS if blood eosinophils ≥3%, or targeted antibiotics if there is positive culture on induced sputum/cough swab. The control group received standard care. The primary outcome was UHCV at 4 months.

RESULTS

60 children, with a median age of 36.5 (range 14-61) months, were randomized. Median blood eosinophils were 5.2 (range 0-21)%, 27 of 60 (45%) children were atopic, and 8 of 60 (13%) had airway bacterial infection. There was no relationship between EVW, MTW and either blood eosinophils, atopic status or infection. 67% in each group were prescribed ICS. 15 of 30 control subjects and 16 of 30 patients in the intervention group had UHCV over 4 months (p = .8). The time to first UHCV was similar. 50% returned adherence monitors; in those, median ICS adherence was 67%. There were no differences in any parameter between those who did and did not have an UHCV.

CONCLUSION

Clinical phenotype was unrelated to allergen sensitization or blood eosinophils. ICS treatment determined by blood eosinophils did not impact UHCV, but ICS adherence was poor.

Eosinophils as Drivers of Severe Eosinophilic Asthma: Endotypes or Plasticity?

Asthma is now recognized as a heterogeneous disease, encompassing different phenotypes driven by distinct pathophysiological mechanisms called endotypes. Common phenotypes of asthma, referred to as eosinophilic asthma, are characterized by the presence of eosinophilia. Eosinophils are usually considered invariant, terminally differentiated effector cells and have become a primary therapeutic target in severe eosinophilic asthma (SEA) and other eosinophil-associated diseases (EADs). Biological treatments that target eosinophils reveal an unexpectedly complex role of eosinophils in asthma, including in SEA, suggesting that "not all eosinophils are equal". In this review, we address our current understanding of the role of eosinophils in asthma with regard to asthma phenotypes and endotypes. We further address the possibility that different SEA phenotypes may involve differences in eosinophil biology. We discuss how these differences could arise through eosinophil "endotyping", viz. adaptations of eosinophil function imprinted during their development, or through tissue-induced plasticity, viz. local adaptations of eosinophil function through interaction with their lung tissue niches. In doing so, we also discuss opportunities, technical challenges, and open questions that, if addressed, might provide considerable benefits in guiding the choice of the most efficient precision therapies of SEA and, by extension, other EADs.

Anti-IL-5 mepolizumab minimally influences residual blood eosinophils in severe asthma

Neutralising antibodies against the cytokine interleukin (IL)-5 have become widely used for the control of severe eosinophilic asthma. Remarkably, patients receiving neutralising anti-IL5 biological therapies retain a very stable population of residual blood eosinophils. Whether these residual eosinophils are endowed with particular biological activity has not yet been studied but is of importance in predicting potential long-term effects of IL5 neutralisation in patients. To tackle the effect of IL5 depletion on residual eosinophils, we used a comparative RNA-sequencing approach and compared the gene expression program of eosinophils arising in IL5-depleted or IL5-replete human or murine hosts, at steady-state in vivo and following in vitro stimulation with the eosinophil-activating alarmin IL33. We compared blood eosinophils from patients with severe allergic eosinophilic asthma treated with anti-IL5 mepolizumab therapy to those of healthy controls and matched asthma patients receiving anti-IgE omalizumab therapy. We made similar comparisons on bone marrow eosinophils from mice genetically deficient or not for IL5. We report that restriction of IL5 availability did not elicit any detectable transcriptional response in steady-state residual eosinophils in mepolizumab-treated patients or IL5-deficient mice, and influenced only a handful of genes in their response to IL33. Together, these results support the notion that treatment with IL5 neutralising antibodies spares a pool of circulating residual eosinophils largely resembling those of healthy individuals.

Precision Medicine for Paediatric Severe Asthma: Current Status and Future Direction

Asthma is a heterogeneous disease, characterised by different phenotypes and endotypes. Precision medicine in asthma refers to the implementation of a targeted therapy for each individual child, based on the identification of treatable traits, including environmental, immunological and genetic factors. Severe asthma in children is associated with increased hospitalisation rates, a lower quality of life, increased healthcare costs and an increased mortality. In the era of new molecular biologics treatments, it is essential to improve deep phenotyping of children with severe asthma in order to deliver the most effective treatment to each individual child. In this review, we discuss the personalised approach to the assessment and management of severe asthma. We explore the indications and use of the currently licensed biologics, as well as the potential of other emerging treatments.

Structured histopathology for endotyping and planning rational treatment in chronic rhinosinusitis

In chronic rhinosinusitis (CRS), endotyping, being based on the pathogenic mechanism, provides a precise picture appropriate for use in clinical practice. Structured histopathological examination of CRS is considered a necessary step in efforts to establish its pathogenesis and improve our endotyping capabilities. Herein we discuss the associations between histopathology and clinical characteristics of CRS patients to assist medical and surgical treatment choices.