Patient characteristics, biomarkers, and exacerbation risk in severe, uncontrolled asthma

[Modern asthma management]

Symptom prevention and remission are the goals of asthma treatment. Precise phenotyping of the patients, including history, lung function, allergology and measurement of type 2 biomarkers, is the essential prerequisite for treatment success. Basic measures, treatment with DMAADs ("disease-modifying anti-asthmatic drugs": predominantly inhaled corticosteroids, biologics, and allergen immunotherapy) and treatment of comorbidities are the cornerstones of modern asthma management. The treatment of upper airway diseases such as allergic rhinitis (often associated with early-onset asthma) or chronic rhinosinusitis (often associated with adult-onset asthma, with 2 forms: either with nasal polyps, CRSwNP, or without nasal polyps, CRSsNP) is of major importance in this regard.

Impact of Clinical Characteristics and Biomarkers on Asthma Impairment and Risk Questionnaire Exacerbation Prediction Ability

BACKGROUND

Complex models combining impairment-based control assessments with clinical characteristics and biomarkers have been developed to predict asthma exacerbations. The composite Asthma Impairment and Risk Questionnaire (AIRQ) with adjustments for demographics (age, sex, race, and body mass index) predicts 12-month exacerbation occurrence similarly to these more complex models.

OBJECTIVE

To examine whether AIRQ exacerbation prediction is enhanced when models are adjusted for a wider range of clinical characteristics and biomarkers.

METHODS

Patients aged 12 years and older completed monthly online surveys regarding exacerbation-related oral corticosteroid use, emergency department or urgent care visits, and hospitalizations. Univariate logistic regressions to predict exacerbations were performed with sociodemographics, comorbidities, exacerbation history, lung function, blood eosinophils, IgE, and FeNO. Significant (P ≤ .05) variables were included in multivariable logistic regressions with and without AIRQ control categories to predict 12-month exacerbations (log odds ratio [95% Wald confidence interval]). Model performances were compared.

RESULTS

Over 12 months, 1,070 patients (70% female; mean [SD] age, 43.9 [19.4] years; 22% non-White; body mass index [SD], 30.6 [8.7]) completed one or more survey (mean [SD], 10.5 [2.8] surveys). In the multivariable analysis, AIRQ control category adjusted for significant clinical characteristics and biomarkers was predictive of one or more exacerbations: odds ratio (95% CI) not well-controlled versus well-controlled: 1.93 (1.41-2.62), very poorly controlled versus well-controlled: 3.81 (2.65-5.47). Receiver operating characteristic area under the curve (AUC) for this more complex model of exacerbation prediction (AUC = 0.72) did not differ from AIRQ (AUC = 0.70). Models with AIRQ performed better than those without AIRQ (AUC = 0.67; P < .05).

CONCLUSION

Costly and time-consuming complex modeling with clinical characteristics and biomarkers does not enhance the strong exacerbation prediction ability of AIRQ.

Burden of Uncontrolled Severe Asthma With and Without Elevated Type-2 Inflammatory Biomarkers

BACKGROUND

Many patients with asthma have type-2 airway inflammation, identified by the presence of biomarkers, including history of allergy, high blood eosinophil (EOS) count, and high fractional exhaled nitric oxide levels.

OBJECTIVE

To assess disease burden in relation to type-2 inflammatory biomarker status (history of allergy, blood EOS count, and fractional exhaled nitric oxide level) in patients with uncontrolled and controlled severe asthma in the NOVEL observational longiTudinal studY (NOVELTY) (NCT02760329).

METHODS

Asthma diagnosis and severity were physician-reported. Control was defined using Asthma Control Test score (uncontrolled <20, controlled ≥20) and/or 1 or more severe physician-reported exacerbation in the previous year. Biomarker distribution (history of allergy, blood EOS count, and fractional exhaled nitric oxide level), symptom burden (Asthma Control Test score, modified Medical Research Council dyspnea scale), health status (St George's Respiratory Questionnaire score), exacerbations, and health care resource utilization were assessed.

RESULTS

Of 647 patients with severe asthma, 446 had uncontrolled and 123 had controlled asthma. Among those with uncontrolled asthma, 196 (44%) had 2 or more positive biomarkers, 187 (42%) had 1 positive biomarker, 325 (73%) had low blood EOS, and 63 (14%) were triple-negative. Disease burden was similarly high across uncontrolled subgroups, irrespective of biomarker status, with poor symptom control (Asthma Control Test score 14.9-16.6), impaired health status (St George's Respiratory Questionnaire total score 46.7-49.4), clinically important breathlessness (modified Medical Research Council grade ≥2 in 47.3%-57.1%), and 1 or more severe exacerbation (70.6%-76.2%).

CONCLUSIONS

Type-2 inflammatory biomarkers did not differentiate disease burden in patients with severe asthma. Patients with low type-2 inflammatory biomarker levels have few biologic therapy options; their needs should be addressed.

Phenotyping of Severe Asthma in the Era of Broad-Acting Anti-Asthma Biologics

Severe asthma is associated with significant morbidity and mortality despite the maximal use of inhaled corticosteroids and additional controller medications, and has a high economic burden. Biologic therapies are recommended for the management of severe, uncontrolled asthma to help to prevent exacerbations and to improve symptoms and health-related quality of life. The effective management of severe asthma requires consideration of clinical heterogeneity that is driven by varying clinical and inflammatory phenotypes, which are reflective of distinct underlying disease mechanisms. Phenotyping patients using a combination of clinical characteristics such as the age of onset or comorbidities and biomarker profiles, including blood eosinophil counts and levels of fractional exhaled nitric oxide and serum total immunoglobulin E, is important for the differential diagnosis of asthma. In addition, phenotyping is beneficial for risk assessment, selection of treatment, and monitoring of the treatment response in patients with asthma. This review describes the clinical and inflammatory phenotypes of asthma, provides an overview of biomarkers routinely used in clinical practice and those that have recently been explored for phenotyping, and aims to assess the value of phenotyping in severe asthma management in the current era of biologics.

Sustained Effectiveness of Benralizumab in Naïve and Biologics-Experienced Severe Eosinophilic Asthma Patients: Results from the ANANKE Study

Purpose

Severe eosinophilic asthma (SEA) patients often present overlapping inflammatory features rendering them eligible for multiple biologic therapies; switching biologic treatment is a strategy adopted to optimize asthma control when patients show partial or no response to previous biologics.

Patients and Methods

ANANKE is a retrospective, multicenter Italian study (NCT04272463). Here, we outline the characteristics and long-term clinical outcomes in naïve-to-biologics and biologics-experienced patients treated with benralizumab for up to 96 weeks. Bio-experienced patients were split into omalizumab and mepolizumab subsets according to the type of biologic previously used.

Results

A total of 124 (76.5%) naïve and 38 (23.5%) bio-experienced patients were evaluated at index date; 13 patients (34.2%) switched from mepolizumab, 21 patients (55.3%) switched from omalizumab, and four patients (10.5%) received both biologics. The mepolizumab subset was characterized by the longest SEA duration (median of 4.6 years), the highest prevalence of chronic rhinosinusitis with nasal polyposis (CRSwNP) (76.5%), and the greatest oral corticosteroid (OCS) daily dosage (median of 25 mg prednisone equivalent). The omalizumab group showed the highest severe annual exacerbation rate (AER) (1.70). At 96 weeks, treatment with benralizumab reduced any and severe AER by more than 87% and 94%, respectively, across all groups. Lung function was overall preserved, with major improvements observed in the mepolizumab group, which also revealed a 100% drop of the median OCS dose. Asthma Control Test (ACT) score improved in the naïve group while its increment was more variable in bio-experienced patients; among these, a marked difference was noticed between omalizumab and mepolizumab subsets (median ACT score of 23.5 and 18, respectively).

Conclusion

Benralizumab promotes durable and profound clinical benefits in naïve and bio-experienced groups, indicating that a nearly complete depletion of eosinophils is highly beneficial in the control of SEA, independently of previous biologic use.

Activated sputum eosinophils associated with exacerbations in children on mepolizumab

BACKGROUND

MUPPITS-2 was a randomized, placebo-controlled clinical trial that demonstrated mepolizumab (anti-IL-5) reduced exacerbations and blood and airway eosinophils in urban children with severe eosinophilic asthma. Despite this reduction in eosinophilia, exacerbation risk persisted in certain patients treated with mepolizumab. This raises the possibility that subpopulations of airway eosinophils exist that contribute to breakthrough exacerbations.

OBJECTIVE

We aimed to determine the effect of mepolizumab on airway eosinophils in childhood asthma.

METHODS

Sputum samples were obtained from 53 MUPPITS-2 participants. Airway eosinophils were characterized using mass cytometry and grouped into subpopulations using unsupervised clustering analyses of 38 surface and intracellular markers. Differences in frequency and immunophenotype of sputum eosinophil subpopulations were assessed based on treatment arm and frequency of exacerbations.

RESULTS

Median sputum eosinophils were significantly lower among participants treated with mepolizumab compared with placebo (58% lower, 0.35% difference [95% CI 0.01, 0.74], P = .04). Clustering analysis identified 3 subpopulations of sputum eosinophils with varied expression of CD62L. CD62Lint and CD62Lhi eosinophils exhibited significantly elevated activation marker and eosinophil peroxidase expression, respectively. In mepolizumab-treated participants, CD62Lint and CD62Lhi eosinophils were more abundant in participants who experienced exacerbations than in those who did not (100% higher for CD62Lint, 0.04% difference [95% CI 0.0, 0.13], P = .04; 93% higher for CD62Lhi, 0.21% difference [95% CI 0.0, 0.77], P = .04).

CONCLUSIONS

Children with eosinophilic asthma treated with mepolizumab had significantly lower sputum eosinophils. However, CD62Lint and CD62Lhi eosinophils were significantly elevated in children on mepolizumab who had exacerbations, suggesting that eosinophil subpopulations exist that contribute to exacerbations despite anti-IL-5 treatment.

Treatable Traits in Pregnant Women with Asthma

BACKGROUND

Asthma is the most common chronic respiratory disease in pregnancy, affecting approximately 8-10% of pregnant women. Uncontrolled asthma is associated with adverse perinatal outcomes, including low birth weight, preterm birth, and maternal complications such as pre-eclampsia.

SUMMARY

A current approach to the management of chronic airway diseases is based on targeting treatable traits. The aim of this review was to define treatable traits in pregnant women with asthma based on recent literature and to determine personalized treatment options according to these traits. Traits addressed in this review that may improve asthma control and pregnancy outcomes are fractional exhaled nitric oxide-based asthma monitoring and treatment, medication adherence and inhalation technique, impaired lung function, smoking cessation and comorbidity including psychological conditions (depression and anxiety), obesity, rhinitis, gastroesophageal reflux disease, chronic rhinosinusitis with or without nasal polyps, and sleep apnea.

KEY MESSAGES

All the treatable traits discussed have the potential to improve asthma control and pregnancy outcomes in pregnant women with asthma. Further research is needed to determine which management approaches are best to improve asthma control during pregnancy, to identify other relevant treatable traits, and to determine whether the treatable trait approach is feasible and beneficial in pregnant women with asthma.

[Precision medicine in the diagnosis and treatment of asthma]

Due to the availability of disease-modifying anti-asthmatic drugs (DMAADs), especially inhaled steroids (alone or in combination with long-acting bronchodilators), biologics and modern allergen immunotherapy, the treatment of asthma has fundamentally changed. The aims of modern asthma precision medicine are prevention of symptoms and the induction and maintenance of asthma remission (long-term asthma control, freedom from exacerbations and stable lung function without the use of systemic steroids). A treat to target approach is used as for other chronic inflammatory diseases in internal medicine: the aim is to achieve remission by an individually tailored treatment with DMAADs; however, the prerequisite for modern asthma precision medicine is asthma phenotyping, including a detailed medical history, lung function testing, allergological diagnostics and measurement of type 2 markers (blood eosinophils and, if available, exhaled nitric oxide, FeNO).

Fractional exhaled nitric oxide-a possible biomarker for risk of obstructive sleep apnea in snorers

STUDY OBJECTIVES

Airway inflammation in patients with obstructive sleep apnea (OSA) has been described and can be assessed by measuring the biomarker fractional exhaled nitric oxide (FeNO). In this pilot study, we investigated FeNO measurements in identification of OSA among persons with snoring.

METHODS

In this study we aimed to investigate (1) if FeNO could be used in screening for OSA, (2) if daytime sleepiness correlated to FeNO levels, and (3) whether asthma affected FeNO levels. Persons with snoring were prospectively included in three primary care ear, nose, and throat clinics. Patients underwent spirometry, FeNO tests, and partial polygraphy. They filled out questionnaires on sinonasal and asthma symptoms, daytime sleepiness, and quality of life. Current smokers, patients with upper airway inflammatory conditions, and patients treated with steroids were excluded.

RESULTS

Forty-nine individuals were included. Median apnea-hypopnea index was 11.4, mean age was 50.9 years, and 29% were females. OSA was diagnosed in 73% of the patients of whom 53% had moderate-severe disease. Patients with moderate-severe OSA had significantly higher FeNO counts than patients with no or mild OSA (P = .024). Patients younger than 50 years with a FeNO below 15 had the lowest prevalence of moderate-severe OSA. No correlation was found between FeNO measurements and daytime sleepiness, and asthma did not affect FeNO levels.

CONCLUSIONS

We found a low prevalence of moderate-severe OSA in persons with snoring when FeNO and age were low. This might be considered in a future screening model, though further studies testing the FeNO cutoff level and the diagnostic accuracy are warranted.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: NO Measurements in Screening for Asthma and OSA, in Patients With Severe Snoring; URL: https://clinicaltrials.gov/study/NCT03964324; Identifier: NCT03964324.

CITATION

Kiaer E, Ravn A, Jennum P, et al. Fractional exhaled nitric oxide-a possible biomarker for risk of obstructive sleep apnea in snorers. J Clin Sleep Med. 2024;20(1):85-92.

Mild asthma is not mild: risk factors and predictive biomarkers for severe acute exacerbations and progression in mild asthma

INTRODUCTION

Asthma is a common chronic respiratory disease characterized by chronic airway inflammation, airway hyperresponsiveness, reversible airflow limitation, and airway remodeling. Mild asthma is the most common type of asthma, but it is the most neglected. Sometimes mild asthma can lead to acute severe exacerbations or even death.

AREAS COVERED

This article reviews the epidemiology, risk factors, and possible predictors of acute severe exacerbations and disease progression in mild asthma to improve the understanding of mild asthma and its severe acute exacerbations and progression.

EXPERT OPINION

There is a necessity to improve asthma patient categorization and redefine mild asthma's concept to heighten patient and physician attention. Identifying mild asthma patients that are highly vulnerable to severe acute exacerbations and researching the mechanisms are future prioritizations.

Phenotyping the Responses to Systemic Corticosteroids in the Management of Asthma Attacks (PRISMA): protocol for an observational and translational pilot study

INTRODUCTION

Asthma and its associated exacerbation are heterogeneous. Although severe asthma attacks are systematically prescribed corticosteroids and often antibiotics, little is known about the variability of response to these therapies. Blood eosinophils and fractional exhaled nitric oxide (FeNO) are type 2 inflammation biomarkers that have established mechanistic, prognostic and theragnostic values in chronic asthma, but their utility in acute asthma is unclear. We speculate that the clinical and biological response to those treatments varies according to inflammometry and microbiological test results.

METHODS AND ANALYSIS

An observational longitudinal pilot study with multimodal clinical and translational assessments will be performed on 50 physician-diagnosed ≥12-year-old asthmatics presenting with an asthma attack and 12 healthy controls, including blood eosinophil count (venous and point-of-care (POC) capillary blood), FeNO and testing for airway infection (sputum cultures and POC nasopharyngeal swabs). People with asthma will be assessed on day 0 and after a 7-day corticosteroid course, with home monitoring performed in between. The primary analysis will be the change in the forced expiratory volume in 1 s according to type 2 inflammatory status (blood eosinophils ≥0.15×109/L and/or FeNO ≥25 ppb) after treatment. Key secondary analyses will compare changes in symptom scores and the proportion of patients achieving a minimal clinically important difference. Exploratory analyses will assess the relationship between clinical, lung function, inflammatory and microbiome parameters; satisfaction plus reliability indices of POC tests; and sex-gender variability in treatment response. Ultimately, this pilot study will serve to plan a larger trial comparing the clinical and biological response to systemic corticosteroids according to inflammatory biomarkers, offering valuable guidance for more personalised therapeutic strategies in asthma attacks.

ETHICS AND DISSEMINATION

The protocol has been approved by the Research Ethics Committee of the CIUSSS de l'Estrie-CHUS, Sherbrooke, Quebec, Canada (#2023-4687). Results will be communicated in an international meeting and submitted to a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT05870215).

Environmental pollutants increase the risks of acute exacerbation in patients with chronic airway disease

Objective

Respiratory infections are a common cause of acute exacerbations in patients with chronic airway disease, however, environmental factors such as air pollution can also contribute to these exacerbations. The study aimed to determine the correlation between pollutant levels and exacerbation risks in areas exposed to environmental pollution sources.

Methods

From 2015 to 2016, a total of 788 patients with chronic airway diseases were enrolled in a study. Their medical records, including hospital visits due to acute exacerbations of varying severity were analyzed. Additionally, data on daily pollutant levels from the Air Quality Monitoring Network from 2014 to 2016 was also collected and analyzed.

Results

Patients with chronic airway disease and poor lung function (FEV1 < 50% or obstructive ventilatory defect) have a higher risk of severe acute exacerbations and are more likely to experience more than two severe acute exacerbations within a year. The study found that in areas exposed to environmental pollution sources, there is a significant correlation between NO2, O3, and humidity with the main causes of severe acute exacerbation. When the levels of NO2 were higher than 16.65 ppb, O3 higher than 35.65 ppb, or humidity higher than 76.95%, the risk of severe acute exacerbation in patients with chronic airway disease increased.

Conclusion

Acute exacerbations of chronic airway disease can be triggered by both the underlying disease state and the presence of air pollution. Computer simulations and early warning systems should be developed to predict acute exacerbations of chronic airway disease based on dynamic changes in air pollution.

Development of an Asthma Exacerbation Risk Prediction Model for Conversational Use by Adults in England

Background

Improving accurate risk assessment of asthma exacerbations, and reduction via relevant behaviour change among people with asthma could save lives and reduce health care costs. We developed a simple personalised risk prediction model for asthma exacerbations using factors collected in routine healthcare data for use in a risk modelling feature for automated conversational systems.

Methods

We used pseudonymised primary care electronic healthcare records from the Clinical Practice Research Datalink (CPRD) Aurum database in England. We combined variables for prediction of asthma exacerbations using logistic regression including age, gender, ethnicity, Index of Multiple Deprivation, geographical region and clinical variables related to asthma events.

Results

We included 1,203,741 patients divided into three cohorts to implement temporal validation: 898,763 (74.7%) in the training sample, 226,754 (18.8%) in the testing sample and 78,224 (6.5%) in the validation sample. The Area under the ROC curve (AUC) for the full model was 0.72 and for the restricted model was 0.71. Using a cut-off point of 0.1, approximately 27 asthma reviews by clinicians per 100 patients would be prevented compared with a strategy that all patients are regarded as high risk. Compared with patients without an exacerbation, patients who exacerbated were older, more likely to be female, prescribed more SABA and ICS in the preceding 12 months, have history of GORD, COPD, anxiety, depression, live in very deprived areas and have more severe disease.

Conclusion

Using information available from routinely collected electronic healthcare record data, we developed a model that has moderate ability to separate patients who had an asthma exacerbation within 3 months from their index date from patients who did not. When comparing this model with a simplified model with variables that can easily be self-reported through a WhatsApp chatbot, we have shown that the predictive performance of the model is not substantially different.

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

[Diagnosis and treatment of asthma: a guideline for respiratory specialists 2023 - published by the German Respiratory Society (DGP) e. V.]

The management of asthma has fundamentally changed during the past decades. The present guideline for the diagnosis and treatment of asthma was developed for respiratory specialists who need detailed and evidence-based information on the new diagnostic and therapeutic options in asthma. The guideline shows the new role of biomarkers, especially blood eosinophils and fractional exhaled NO (FeNO), in diagnostic algorithms of asthma. Of note, this guideline is the first worldwide to announce symptom prevention and asthma remission as the ultimate goals of asthma treatment, which can be achieved by using individually tailored, disease-modifying anti-asthmatic drugs such as inhaled steroids, allergen immunotherapy or biologics. In addition, the central role of the treatment of comorbidities is emphasized. Finally, the document addresses several challenges in asthma management, including asthma treatment during pregnancy, treatment of severe asthma or the diagnosis and treatment of work-related asthma.

Characterization and Factors Associated with Poor Asthma Control in Adults with Severe Eosinophilic Asthma

A study was conducted in 98 adult patients diagnosed with severe eosinophilic asthma (73.5% women, mean age 47.2 years) and followed prospectively for 1 year. The aim of the study was to characterize this population and to identify factors associated with poor prognosis at 1 year of follow-up. At the initial visit, uncontrolled severe asthma was diagnosed in 87.7% of patients. Allergic sensitization was observed in 81.7% (polysensitization in 17.3%), with clinically significant allergic asthma in 45%. The mean percentage of sputum eosinophils was 4.7% (standard deviation(SD) 6.3%) and the mean (SD) blood eosinophil count 467 (225) cells/µL. Almost half of the patients (48.3%) had sputum eosinophilia (>3% eosinophils). Sputum eosinophils correlated significantly with peripheral eosinophilia (p = 0.004) and, to a lesser extent, with fractional exhaled nitric oxide (FeNO) (p = 0.04). After 1 year, 48 patients (49%) had uncontrolled asthma in all visits, and 50 (51%) had controlled asthma in some visits. Airway obstruction (FEV₁ < 80% predicted) was the main reason for uncontrolled asthma. In the multivariate analysis, an obstructive pattern (odds ratio (OR) 7.45, 95% confidence interval (CI) 2.41-23.03, p < 0.0001) and the patient's age (OR 1.045, 95% CI 1.005-1.086, p = 0.026) were independent predictors of poor asthma control. In adult-onset and long-standing asthma, serum interleukin (IL) IL-17 was higher in the uncontrolled asthma group. This study contributes to characterizing patients with severe eosinophilic asthma in real-world clinical practice.

Ethnic variation in asthma healthcare utilisation and exacerbation: systematic review and meta-analysis

Background

Patients from ethnic minority groups (EMGs) frequently report poorer asthma outcomes; however, a broad synthesis summarising ethnic disparities is yet to be undertaken. What is the magnitude of ethnic disparities in asthma healthcare utilisation, exacerbations and mortality?

Methods

MEDLINE, Embase and Web of Science databases were searched for studies reporting ethnic variation in asthma healthcare outcomes (primary care attendance, exacerbation, emergency department (ED) visits, hospitalisation, hospital readmission, ventilation/intubation and mortality) between White patients and those from EMGs. Estimates were displayed using forest plots and random-effects models were used to calculate pooled estimates. We conducted subgroup analyses to explore heterogeneity, including by specific ethnicity (Black, Hispanic, Asian and other).

Results

65 studies, comprising 699 882 patients, were included. Most studies (92.3%) were conducted in the United States of America (USA). Patients from EMGs had evidence suggestive of lower levels of primary care attendance (OR 0.72, 95% CI 0.48-1.09), but substantially higher ED visits (OR 1.74, 95% CI 1.53-1.98), hospitalisations (OR 1.63, 95% CI 1.48-1.79) and ventilation/intubation (OR 2.67, 95% CI 1.65-4.31) when compared to White patients. In addition, we found evidence suggestive of increased hospital readmissions (OR 1.19, 95% CI 0.90-1.57) and exacerbation rates (OR 1.10, 95% CI 0.94-1.28) among EMGs. No eligible studies explored disparities in mortality. ED visits were much higher among Black and Hispanic patients, while Asian and other ethnicities had similar rates to White patients.

Conclusions

EMGs had higher secondary care utilisation and exacerbations. Despite the global importance of this issue, the majority of studies were performed in the USA. Further research into the causes of these disparities, including whether these vary by specific ethnicity, is required to aid the design of effective interventions.

Mild asthma: Lessons learned and remaining questions

Patients living with mild disease represent the largest proportion of asthma patients. There are significant challenges in proposing a definition that would best describe these patients, while also accurately identifying at-risk individuals. Current literature suggests considerable inflammatory and clinical heterogeneity within this group. Research has shown that these patients are at risk of poor control, exacerbations, lung function decline, and death. Despite conflicting data on its prevalence, eosinophilic inflammation appears to be a predictor of poorer outcomes in mild asthma. There is an immediate need to better understand phenotypic clusters in mild asthma. It is also important to understand factors that influence disease progression and remission, as it is evident that both vary in mild asthma. Guided by robust literature that supports inhaled corticosteroid-based strategies over short-acting beta-agonist (SABA) reliant regimens, the management of these patients has evolved considerably. Unfortunately, SABA use remains high in clinical practice despite strong advocacy from the Global Initiative for Asthma. Future mild asthma research should explore the role of biomarkers, develop prediction tools based on composite risk scores, and explore targeted therapies at least for at-risk individuals.

Validation of a Pathological Score for the Assessment of Bronchial Biopsies in Severe Uncontrolled Asthma: Beyond Blood Eosinophils

BACKGROUND

Blood eosinophil count (BEC) is currently used as a surrogate marker of T2 inflammation in severe asthma but its relationship with tissue T2-related changes is elusive. Bronchial biopsy could add reliable information but lacks standardization.

OBJECTIVES

To validate a systematic assessment of the bronchial biopsy for the evaluation of severe uncontrolled asthma (SUA) by standardizing a pathological score.

METHODS

A systematic assessment of submucosal inflammation, tissue eosinophilic count/field (TEC), goblet cells hyperplasia, epithelial changes, basement membrane thickening, prominent airway smooth muscle and submucosal mucous glands was initially agreed and validated in representative bronchial biopsies of 12 patients with SUA by 8 independent pathologists. In a second phase, 62 patients with SUA who were divided according to BEC≥300cells/mm³ or less underwent bronchoscopy with bronchial biopsies and the correlations between the pathological findings and the clinical characteristics were investigated.

RESULTS

The score yielded good agreement among pathologists regarding submucosal eosinophilia, TEC, goblet cells hyperplasia and mucosal glands (ICC=0.85, 0.81, 0.85 and 0.87 respectively). There was a statistically significant correlation between BEC and TEC (r=0.393, p=0.005) that disappeared after correction by oral corticosteroids (OCS) use (r=0.170, p=0.307). However, there was statistically significant correlation between FeNO and TEC (r=0.481, p=0.006) that was maintained after correction to OCS use (r=0.419, p=0.021). 82.4% of low-BEC had submucosal eosinophilia, 50% of them moderate to severe.

CONCLUSION

A standardized assessment of endobronchial biopsy is feasible and could be useful for a better phenotyping of SUA especially in those receiving OCS.

Long-term effectiveness of benralizumab in severe eosinophilic asthma patients treated for 96-weeks: data from the ANANKE study

BACKGROUND

The efficacy of benralizumab has been broadly demonstrated in severe eosinophilic asthma (SEA), but only few real-life studies evaluated its long-term effects. Here we present novel data from the ANANKE study in which a large cohort of SEA patients was treated for up to 96 weeks.

METHODS

ANANKE (NCT04272463) is an observational retrospective Italian study investigating the key characteristics of SEA patients (collected during the 12 months prior to benralizumab initiation) and the clinical outcomes during benralizumab treatment (annual exacerbation rate [AER], lung function, asthma control, OCS use, healthcare resource utilization). A post hoc analysis was also conducted in groups of patients based on history of previous biologic therapy (bio-experienced versus naïve patients). Analyses were descriptive only.

RESULTS

Before benralizumab initiation, evaluable SEA patients (N = 162, 61.1% females, mean age 56.0 ± 12.7) showed a median blood eosinophil count (BEC) of 600 cells/mm³ (IQR: 430-890). Patients experienced frequent exacerbations (annualized exacerbation rate [AER]: 4.10, severe AER: 0.98), with impaired lung function and poor asthma control (median ACT score: 14) despite 25.3% reported oral corticosteroid (OCS) use. Nasal polyposis was present in 53.1% patients; 47.5% patients were atopic. After 96 weeks since the start of benralizumab, nearly 90% patients were still on treatment; benralizumab dramatically decreased exacerbations (AER: - 94.9%; severe AER: - 96.9%), improved respiratory parameters (median increase in pre-bronchodilator forced expiratory volume [pre-BD FEV1]: + 400 mL) and asthma control (median ACT score: 23) while eliminating OCS in 60% patients. Importantly, benralizumab effects were either maintained or progressively improved over time, accompanied by a nearly complete depletion of BEC. Benralizumab reduced AER both in naïve (any AER: - 95.9%; severe AER: - 97.5%) and bio-experienced patients (any AER: - 92.4%; severe AER: - 94.0%).

CONCLUSIONS

Profound and sustained improvements in all asthma outcomes were observed with benralizumab. The correct identification of patients' eosinophilic-driven asthma phenotype was essential to ensure the achievement of such remarkable results.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04272463.

Toward a Predict and Prevent Approach in Obstructive Airway Diseases

Asthma and chronic obstructive pulmonary disease are currently diagnosed and treated after the demonstration of variable airflow limitation and symptoms. Under this framework, undiagnosed and unchecked airway inflammation is associated with recurrent acute attacks, airway remodeling, airflow limitation, adverse effects of corticosteroids, and impaired quality of life, ultimately leading to the collection of side effects termed "people remodeling." This one-size-fits-all damage control approach aims to control symptoms and treat exacerbations rather than modify the underlying disease process. The advent of highly effective therapies targeting proximal drivers of airway inflammation calls for a paradigm shift; upstream-acting therapies offer potential to alter the disease course and achieve clinical remission. We propose moving away from downstream firefighting and toward a "predict and prevent" model, measuring inflammation and providing anti-inflammatory therapy early, without waiting for further clinical deterioration. Much in the same way that high blood pressure and cholesterol are used to predict and prevent heart attacks, in asthma, elevated blood eosinophils and/or exhaled nitric oxide can be used to predict and prevent asthma attacks. We also advocate moving research further upstream by identifying patients with subclinical airway inflammation or disease who may be at risk of progressing to airflow limitation and associated morbidities and intervening early to prevent them. In summary, we call for a predict and prevent approach in obstructive airway disease.

A Multi-Center Study of the Prevalence and Characteristics of Eosinophilic Phenotype and High IgE Levels Among Chinese Patients with Severe Asthma

Background

Patients with severe asthma have higher total- and asthma-related health burden than those whose disease is not severe. Recent medical advances in biologic therapies allow better control of asthma characterized by type 2 inflammation.

Objective

To study the prevalence of eosinophilic phenotype and IgE levels in Chinese with severe asthma, and the relationship of these type 2 characteristics with asthma control, exacerbations and lung function.

Methods

This was a multicenter cross-sectional observational study in Hong Kong, in Chinese adults with asthma on Step 4 or 5 of GINA treatment. Their blood eosinophil counts and total IgE levels were measured, and the relationship of these phenotypic parameters to the number of exacerbations in the past 12 months, and to symptom control in the past 4 weeks, were investigated.

Results

A total of 232 subjects were recruited from 6 centers. The mean age was 53.9±12.9 years, with 86 (37.1%) male, and the duration of diagnosed asthma was 26.2±15.7 years. A T-helper 2 (Th2) phenotype indicated by elevated eosinophils and/or IgE was present in 169 (72.8%) of patients. Of 232 patients, 43% had an eosinophilic phenotype (blood eosinophil count ≥300 cell/mm³), while 59% had high total IgE levels of >100 IU/mL (overlap with eosinophilic phenotype in 30%) and 44% had IgE levels of >150 IU/mL (overlap with eosinophilic phenotype in 22%). Subjects with eosinophilic phenotype and IgE >150 IU/mL had a higher rate (1.8 times) of uncontrolled asthma compared with those without such a combination.

Conclusion

In Chinese adults with severe asthma defined by the use of conventional maintenance medication regimens, the prevalence of Th2 inflammation is comparable to that reported from other ethnic populations. Those with both eosinophil count ≥300 cell/mm³ and high IgE levels >150 IU/mL had a higher rate of uncontrolled asthma compared with those without a combination of these features.

Clinical Trial Design Innovations for Precision Medicine in Asthma

Severe asthma is a spectrum disorder with numerous subsets, many of which are defined by clinical history and a general predisposition for T2 inflammation. Most of the approved therapies for severe asthma have required clinical trial designs with population enrichment for exacerbation frequency and/or elevation of blood eosinophils. Moving beyond this framework will require trial designs that increase efficiency for studying nondominant subsets and continue to improve upon biomarker signatures. In addition to reviewing the current literature on biomarker-informed trials for severe asthma, this chapter will also review the advantages of master protocols and adaptive design methods for establishing the efficacy of new interventions in prospectively defined subsets of patients. The incorporation of methods that allow for data collection outside of traditional study visits at academic centers, called remote decentralized trial design, is a growing trend that may increase diversity in study participation and allow for enhanced resiliency during the COVID-19 pandemic. Finally, reaching the goals of precision medicine in asthma will require increased emphasis on effectiveness studies. Recent advances in real-world data utilization from electronic health records are also discussed with a view toward pragmatic trial designs that could also incorporate the evaluation of biomarker signatures.

Potential determinants of T helper 2 markers and their distribution in school-aged children

BACKGROUND

There is growing data on T helper 2 (Th2) biomarker determinants in adult populations. However, the determinants and typical range of these biomarkers have not been well studied in general populations of children. Therefore, we assessed the determinants and typical range of three Th2 biomarkers, including blood eosinophils, FeNO, and serum total IgE in 9-11-year-old children in a prospective birth cohort.

METHODS

We examined the pre- and postnatal factors associated with Th2 biomarkers using multivariable logistic regression analysis (n = 428) and extended the results to the original cohort (n = 17,009) using inverse probability weighting. We also measured typical Th2 biomarker distribution in all examined children and healthy participants without allergic diseases (n = 180).

RESULTS

At age 9-11, wheeze (odds ratio (OR) 7.63), rhinitis (OR 3.14), and eczema (OR 2.46) were significantly associated with increased blood eosinophils. All three allergic conditions were associated with FeNO and total serum IgE, but the ORs were smaller than those for blood eosinophils. Secondhand smoking was inversely associated with the blood eosinophils (OR, 0.38). Similar results were found in the original cohort. Male sex and prenatal factors (maternal smoking and parental history of allergies) were not independent predictors of high Th2 levels.

CONCLUSIONS

In addition to wheezing and rhinitis, eczema and secondhand smoke exposure are independent factors for Th2 biomarker interpretation in children. Furthermore, the typical values and cutoff values of blood eosinophils in adults may not be applicable to children.

Baseline FeNO Independently Predicts the Dupilumab Response in Patients With Moderate-to-Severe Asthma

BACKGROUND

FeNO may have a role as both a prognostic and predictive biomarker in combination with eosinophils for assessing responsiveness to some biological therapies.

OBJECTIVE

We evaluated the value of baseline FeNO, adjusted for baseline blood eosinophil levels and other clinical characteristics, as an independent predictor of treatment response to dupilumab in patients with uncontrolled moderate-to-severe asthma.

METHODS

We performed a post hoc analysis of LIBERTY ASTHMA QUEST (NCT02414854), a phase 3, double-blind study in patients aged 12 years and older with uncontrolled moderate-to-severe asthma, who received dupilumab 200 or 300 mg, or placebo every 2 weeks up to 52 weeks. We assessed the annualized event rate of severe exacerbations and least-squares mean change from baseline in prebronchodilator FEV₁ at weeks 12 and 52 in relationship to baseline FeNO, adjusted for eosinophils and other clinical characteristics.

RESULTS

The annualized event rate increased with increasing baseline FeNO in placebo and decreased in dupilumab groups. The relative risk of severe exacerbations was 22·7%, 58·3%, and 69·3% lower for dupilumab versus placebo for the FeNO less than 25, 25 to less than 50, and 50 and greater parts per billion subgroups. The magnitude of FEV₁ improvement increased with higher baseline FeNO for dupilumab and was consistent across the continuum of FeNO levels in placebo. Both findings were independent of blood eosinophil levels. Significant differences were observed between FeNO subgroups.

CONCLUSIONS

Increased baseline FeNO was associated with greater clinical effects in dupilumab versus placebo independently of eosinophil levels and other clinical characteristics.

Clinical Features and Efficacy of Benralizumab in Patients with Blood Eosinophil Count Between 300 and 450 Cells/mm3: A Post Hoc Analysis from the ANANKE Study

PURPOSE

Benralizumab effectively reduces severe eosinophilic asthma (SEA) exacerbations in patients with a wide range of baseline blood eosinophil count (BEC). Patients included in real-world studies are often characterized by high mean/median BEC, while patients with BEC close to 300 cells/mm3 are poorly represented. This post hoc analysis from the Italian study ANANKE aims to define the clinical features and corroborate the efficacy of benralizumab in real world in the BEC 300-450 cells/mm3 subset of patients.

PATIENTS AND METHODS

Post hoc analysis of the Italian, multicenter, observational, retrospective real-life study ANANKE (NCT04272463). Baseline clinical and laboratory characteristics were collected in the 12 months prior to benralizumab treatment and presented for a BEC 300-450 cells/mm3 subgroup of patients. Change over time of BEC, annualized exacerbation rate (AER), asthma control (ACT), lung function and oral corticosteroid (OCS) use at 16, 24 and 48 weeks after benralizumab introduction were collected.

RESULTS

A total of 164 patients were analyzed, 34 of whom with a BEC of 300-450 cells/mm3. This subgroup was more likely to be female (64.7%), with lower rates of severe exacerbations at baseline when compared to the total population (0.69 vs 1.01). After 48 weeks of benralizumab treatment, the BEC 300-450 subset showed similar reductions in AER (-94.8% vs -92.2%) and OCS use (median dose reduction of 100% in both groups), as well as improvement in ACT score (median scores 22.5 vs 22) and lung function (pre-BD FEV1: +200 mL vs +300 mL) when compared to the total population. No discontinuations for safety reasons were registered.

CONCLUSION

At baseline, apart from lower severe exacerbation rate, the BEC 300-450 cells/mm3 subset of patients is comparable to the total population prescribed with benralizumab. In this real-life study, benralizumab is as effective in BEC 300-450 patients as in the total population.

Differential role of mucus plugs in asthma: Effects of smoking and association with airway inflammation

BACKGROUND

The physiological importance of mucus plugs in computed tomography (CT) imaging is being increasingly recognized. However, whether airway inflammation and smoking affect the association between mucus plugs and clinical-physiological outcomes in asthma remains to be elucidated. The objective of this study is to examine how airway inflammation and/or smoking affect the correlation of CT-based mucus plug scores with exacerbation frequency and airflow limitation indices in asthma.

METHODS

A total of 168 patients with asthma who underwent chest CT and sputum evaluation were enrolled and classified in eosinophilic asthma (EA; n = 103) and non-eosinophilic asthma (NEA; n = 65) groups based on sputum eosinophil percentage (cut-off: 3%). The mucus plug score was defined as the number of lung segments with mucus plugs seen on CT.

RESULTS

More mucus plugs were detected on CT scans in the EA group than in the NEA group, regardless of smoking status. Mucus plug score and exacerbation frequency during one year after enrollment were significantly associated in the EA group but not in the NEA group after adjusting for demographics, blood eosinophil count, and fractional exhaled nitric oxide. Mucus plug score was associated with percentage of predicted forced expiratory volume in 1 s in non-smoking individuals in the EA and NEA group and in smoking individuals in the EA group but not in the NEA group after adjusting for demographics.

CONCLUSIONS

The association of mucus plug score with exacerbation frequency and reduced lung function may vary due to airway inflammatory profile and smoking status in asthma.

Biologics for chronic severe asthma: a network meta‐analysis

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To evaluate the benefits and harms of biological agents targeting type‐2 inflammation (benralizumab, dupilumab, mepolizumab, omalizumab, reslizumab, tezepelumab) in people with severe asthma, with a network meta‐analysis and to rank agents by effectiveness.

Phenotyping, Precision Medicine, and Asthma

The traditional one-size-fits all approach based on asthma severity is archaic. Asthma is a heterogenous syndrome rather than a single disease entity. Studies evaluating observable characteristics called phenotypes have elucidated this heterogeneity. Asthma clusters demonstrate overlapping features, are generally stable over time and are reproducible. What the identification of clusters may have failed to do, is move the needle of precision medicine meaningfully in asthma. This may be related to the lack of a straightforward and clinically meaningful way to apply what we have learned about asthma clusters. Clusters are based on both clinical factors and biomarkers. The use of biomarkers is slowly gaining popularity, but phenotyping based on biomarkers is generally greatly underutilized even in subspecialty care. Biomarkers are more often used to evaluate type 2 (T2) inflammatory signatures and eosinophils (sputum and blood), fractional exhaled nitric oxide (FeNO) and serum total and specific immunoglobulin (Ig) E reliably characterize the underlying inflammatory pathways. Biomarkers perform variably and clinicians must be familiar with their advantages and disadvantages to accurately apply them in clinical care. In addition, it is increasingly clear that clinical features are critical in understanding not only phenotypic characterization but in predicting response to therapy and future risk of poor outcomes. Strategies for asthma management will need to leverage our knowledge of biomarkers and clinical features to create composite scores and risk prediction tools that are clinically applicable. Despite significant progress, many questions remain, and more work is required to accurately identify non-T2 biomarkers. Adoption of phenotyping and more consistent use of biomarkers is needed, and we should continue to encourage this incorporation into practice.

Plasma immunoglobulin E and risk of exacerbation and mortality in chronic obstructive pulmonary disease: A contemporary population-based cohort

BACKGROUND

Novel biomarkers and targeted treatments are needed for patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To test the hypothesis that high plasma immunoglobulin (Ig)E concentrations associate with increased risk of exacerbation and mortality in individuals with COPD in the general population.

METHODS

Among 46,598 adults in the Copenhagen General Population Study, we included 1559 with COPD, defined as forced expiratory volume in 1 second/forced vital capacity < 0.70 and forced expiratory volume in 1 second < 80% predicted in individuals aged ≥ 40 years with chronic respiratory symptoms and smoking exposure ≥ 10 pack-years, and without asthma. We assessed risk of future severe exacerbation and all-cause mortality according to baseline plasma IgE ≥ 76 IU/mL, a clinical cutoff for omalizumab treatment in severe asthma.

RESULTS

During 14 years of follow-up (median, 6.9; interquartile range, 3.4), we recorded 224 severe exacerbations and 434 deaths in 1559 individuals with COPD. Individuals with COPD with IgE ≥ 76 IU/mL vs those with < 76 IU/mL had a multivariable adjusted hazard ratio (HR) of 1.43 (95% confidence interval, 1.07-1.89) for severe exacerbation and 1.30 (1.05-1.62) for all-cause mortality. Compared with individuals with IgE < 76 IU/mL and blood eosinophils < 300 cells/µL, the multivariable adjusted HR for severe exacerbation was 1.12 (0.76-1.67) for those with IgE < 76 IU/mL and blood eosinophils ≥ 300 cells/µL, 1.62 (1.17-2.24) for IgE ≥ 76 IU/mL and blood eosinophils < 300 cells/µL, and 1.06 (0.63-1.77) for those with IgE ≥ 76 IU/mL and blood eosinophils ≥ 300 cells/µL. Corresponding HRs for all-cause mortality were 1.27 (0.99-1.63), 1.47 (1.14-1.88), and 1.17 (0.83-1.64), respectively.

CONCLUSION

High plasma IgE was associated with an increased risk of severe exacerbation and all-cause mortality in individuals with COPD in the general population, independent of blood eosinophils.

Treatment Resistance in Severe Asthma Patients With a Combination of High Fraction of Exhaled Nitric Oxide and Low Blood Eosinophil Counts

Background: Combining a fraction of exhaled nitric oxide (FeNO) and blood eosinophil count (B-EOS) may be a useful strategy for administration of biologics such as anti-IgE or anti-IL-5 to patients with type 2 inflammatory-predominant severe asthma and is important to be elucidated considering the increasing use of biologics.

Methods: This cross-sectional study analyzed the clinical data from 114 adult patients with severe asthma, who were treated at Saitama Medical University Hospital. The eligible patients were stratified into four subgroups defined by thresholds of FeNO and blood eosinophil (B-EOS) counts to detect sputum eosinophilia, using the receiver operating characteristic curve analysis. A total of 75 patients with optimal samples were stratified into four subtypes defined by thresholds of sputum eosinophilia and neutrophilia. Clinical characteristics, pattern of biologics, and distribution of sputum subtypes were analyzed in the stratified subclasses according to the FeNO and B-EOS thresholds. The asthma exacerbation (AE)-free time of the FeNO/B-EOS subgroups and any biologics treatment including anti-IgE or anti-IL-5 use were examined using the Kaplan–Meier method. The hazard ratios (HRs) for AE-free time were examined using the Cox proportional hazard model.

Results: The optimal cutoff values for prediction of sputum eosinophilia were defined as ≥2.7% wherein for FeNO as ≥27 ppb and B-EOS as ≥265/µL were considered. The high-FeNO subgroups showed significant high total IgE, compared with the low FeNO. The high-FeNO/high-B-EOS and the high-FeNO/low-B-EOS subgroups showed the largest prevalence of mepolizumab and benralizumab use among the other FeNO/B-EOS, respectively. The high-FeNO/low-B-EOS showed the largest frequency of AEs, high HR, and the shortest AE-free time, among the other FeNO/B-EOS. The sputum eosinophil-predominant subtype was the great majority in the high FeNO/high B-EOS. A diverse distribution of sputum leukocyte-predominant subtype was observed in the other FeNO/B-EOS. The subsequent AE-free time and its HR were comparable among the biologics use groups.

Conclusion: The strategy of classifying severe asthma based on the combination of FeNO and B-EOS proposes particular refractory type 2 severe asthma and underlying airway inflammation as a feasible trait for optimal biologics use.

Blood eosinophils, fractional exhaled nitric oxide and the risk of asthma attacks in randomised controlled trials: protocol for a systemic review and control arm patient-level meta-analysis for clinical prediction modelling

INTRODUCTION

The reduction of the risk of asthma attacks is a major goal of guidelines. The fact that type-2 inflammatory biomarkers identify a higher risk, anti-inflammatory responsive phenotype is potentially relevant to this goal. We aim to quantify the relation between blood eosinophils, exhaled nitric oxide (FeNO) and the risk of severe asthma attacks.

METHODS AND ANALYSIS

A systematic review of randomised controlled trials (RCTs) will be conducted by searching MEDLINE from January 1993 to April 2021. We will include RCTs that investigated the effect of fixed treatment(s) regimen(s) on severe asthma exacerbation rates over at least 24 weeks and reported a baseline value for blood eosinophils and FeNO. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and the methodological appraisal of the studies will be assessed by the Cochrane Risk-of-Bias Tool for RCTs. Study authors will be contacted to request anonymised individual participant data (IPD) for patients randomised to the trial's control arm. An IPD meta-analysis will be performed for multivariable prognostic modelling with performance assessment (calibration plots and the c-statistic) in a cross-validation by study procedure. The outcome to predict is the absolute number of severe asthma attacks to occur in the following 12 months if anti-inflammatory therapy is not changed (ie, annualised number of attacks requiring ≥3 days of systemic corticosteroids and/or hospitalisation if the patient was randomised to the control arm of an RCT). A summary prognostic equation and risk stratification chart will be reported as a basis for further analyses of individualised treatment benefit.

ETHICS AND DISSEMINATION

The protocol has been reviewed by the relevant Oxford academic ethics committee and found to comprise fully anonymised data not requiring further ethical approbation. Results will be communicated in an international meeting and submitted to a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42021245337.

Considering biomarkers in asthma disease severity

Amongst patients with asthma, reliance on the type/dose of prescribed medication and symptom control does not adequately capture those at risk of adverse outcomes, and we need biomarkers for risk and treatment stratification which are consistently accurate, readily quantifiable and reproducible. The majority of patients with severe asthma, regardless of age, have predominant type-2 (T2) inflammation mediated disease, making airway/blood eosinophils, FeNO, periostin and/or allergic sensitization potentially important biomarkers for severe disease. In both adult and pediatric asthma, there is scope to improve prediction of severe attacks by using a composite T2 biomarkers of blood eosinophils and FeNO. Technological advances in component-resolved diagnostics (CRD) microarray technologies coupled with the development of interpretation software offer a possibility to use CRD as biomarkers of asthma severity amongst sensitized asthmatics. Genetic predisposition and polygenic risk scores of relevant traits (e.g., lung function, host immune responses, biomarkers of exposure from the indoor and outdoor environment, infection and microbial dysbiosis) may also contribute to prediction algorithms. We challenge the idea that asthma can be accurately defined in an individual patient by a discrete and static "endotype" (e.g., T2-high asthma). As we traverse the new era of molecular endotyping in asthma, we need to understand how relevant mechanisms impact patient outcomes, and in parallel develop new tools and approaches to stratify therapies and define individual patient trajectories.

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.

Derivation of a prototype asthma attack risk scale centred on blood eosinophils and exhaled nitric oxide

Reduction of the risk of asthma attacks is a major goal of current asthma management. We propose to derive a risk scale predicting asthma attacks based on the blood eosinophil count and exhaled nitric oxide (FeNO). Biomarker-stratified trial-level attack rates were extracted and pooled from the control arms of the Novel START, CAPTAIN, QUEST, Benralizumab Phase 2b, PATHWAY, STRATOS 1–2 and DREAM trials (n=3051). These were used to derive rate ratios and the predicted asthma attack rate for different patient groups. The resultant prototype risk scale shows potential to predict asthma attacks, which may be prevented by anti-inflammatory treatment.

How I do it. Work-up of severe asthma

CASE EXAMPLE

A 56-year-old gentleman has difficult to control asthma and a history of four exacerbations in the prior 12 months despite high-dose inhaled corticosteroids (ICS) and additional controller therapies. Is he suitable for more advanced therapeutic options?

SCOPE OF REVIEW

We herein review the clinical assessment of a patient with suspected severe asthma, discuss factors contributing to poor asthma control and how biomarkers assist in disease investigation and stratification.

HOW I DO IT

The key components of our multidisciplinary approach are to confirm an asthma diagnosis and adherence to treatment, to assess any contributing comorbidities or confounding factors, and to stratify what type of asthma our patient has. The combination of spirometry and repeated measures of key biomarkers of type-2 airway inflammation - the blood eosinophil count and fractional exhaled nitric oxide - identifies whether poor disease control is driven by uncontrolled, ICS-resistant type-2 airway inflammation or ongoing airflow obstruction. A failure to elicit evidence of either suggests an alternative driver for the patient's symptoms including chronic airway infection and non-asthma causes. Each phenotype represents a treatable trait that requires a specific targeted approach. Critically, steroids can cause harm and their use should be guided by objective evidence of inflammation rather than symptoms alone.

CASE CONCLUSION

After assessment of treatment adherence and exclusion of relevant comorbidities, the patient was found to have severe asthma with ICS-resistant type-2 airway inflammation. We will consider additional treatment options at our next appointment (Part 2/2 of this How I Do It series).