Severe asthma is a heterogeneous disease with different phenotypes based on clinical, functional or inflammatory parameters. In particular, the eosinophilic phenotype is associated with type 2 inflammation and increased levels of interleukin (IL)‐4, IL‐5 and IL‐13). Monoclonal antibodies that target the eosinophilic inflammatory pathways (IL‐5R and IL‐5), namely mepolizumab, reslizumab, and benralizumab, are effective and safe for severe eosinophilic asthma. Eosinophils threshold represents the most indicative biomarker for response to treatment with all three monoclonal antibodies. Improvement in asthma symptoms scores, lung function, the number of exacerbations, history of late‐onset asthma, chronic rhinosinusitis with nasal polyposis, low oral corticosteroids use and low body mass index represent predictive clinical markers of response. Novel Omics studies are emerging with proteomics data and exhaled breath analyses. These may prove useful as biomarkers of response and non‐response biologics. Moreover, future biomarker studies need to be undertaken in paediatric patients affected by severe asthma. The choice of appropriate biologic therapy for severe asthma remains challenging. The importance of finding biomarkers that can predict response continuous an open issue that needs to be further explored. This review describes the clinical effects of targeting the IL‐5 pathway in severe asthma in adult and paediatric patients, focusing on predictors of response and non‐response.

Background: The use of anti-interleukin-5 (IL5) for severe asthma is based on criteria from randomised controlled trials (RCTs), but in real-life patients might not fulfil the eligibility criteria but may benefit from biologics. We aimed to characterise patients starting anti-IL5(R) in Europe and evaluate the discrepancies between initiation of anti-IL5(R) in real life and in RCTs.Materials and methods: We performed a cross-sectional analysis with data from the severe asthma patients at the start of anti-IL5(R) in the Severe Heterogeneous Asthma Research collaboration Patient-centred (SHARP Central) registry. We compared the baseline characteristics of the patients starting anti-IL5(R) from 11 European countries within SHARP with the baseline characteristics of the severe asthma patients from 10 RCTs (four for mepolizumab, three for benralizumab and three for reslizumab). Patients were evaluated following eligibility criteria from the RCTs of anti-IL5 therapies.Results: Patients starting anti-IL5(R) in Europe (n=1231) differed in terms of smoking history, clinical characteristics and medication use. The characteristics of severe asthma patients in the SHARP registry differed from the characteristics of patients in RCTs. Only 327 (26.56%) patients fulfilled eligibility criteria of all the RCTs; 24 patients were eligible for mepolizumab, 100 for benralizumab and 52 reslizumab. The main characteristics of ineligibility were: ≥10 pack-years, respiratory diseases other than asthma, Asthma Control Questionnaire score ≤1.5 and low-dose inhaled corticosteroids.Conclusion: A large proportion of patients in the SHARP registry would not have been eligible for anti-IL5(R) treatment in RCTs, demonstrating the importance of real-life cohorts in describing the efficacy of biologics in a broader population of patients with severe asthma.

Surfactant decreases the surface tension of peripheral airways and modulates the immunological responses of the lung. The alterations of surfactant due to the airway inflammation suggest a role in the pathogenesis of asthma. We aim to test the hypothesis that serum levels of SP-A (Surfactant Protein A) and SP-D (Surfactant Protein-D) are altered in patients with mild asthma compared to healthy controls and those alterations are related to functional abnormalities of peripheral airways, which are an early marker of progression of asthma. In this pilot study, we recruited 20 mild asthmatics and 10 healthy controls. We measured serum SP-A and SP-D and all subjects underwent clinical, lung functional and biological assessments. Serum SP-D was significantly higher in asthmatics compared to healthy controls (mean (SD) values: 7.9(4.65) vs 3.31(1.71) ng ml ⁻¹ , p -value: 0.008). In the asthmatic group, serum SP-D was significantly correlated to CalvNO (alveolar NO concentration) ( R -squared: 0.26; p -value: 0.014). These preliminary findings suggest that serum SP-D could be used as a lung-specific biomarker of small airways damage thus predicting the progression to the most severe forms of asthma.

Asthma is a chronic respiratory disease that can lead to exacerbations, defined as acute episodes of worsening respiratory symptoms and lung function. Predicting the occurrence of these exacerbations is an important goal in asthma management. The measurement of exhaled breath by electronic nose (eNose) may allow for the monitoring of clinically unstable asthma and exacerbations. However, data on its ability to perform this is lacking. We aimed to evaluate whether eNose could identify patients that recently had asthma exacerbations. We performed a cross-sectional study, measuring exhaled breath using the SpiroNose in adults with a physician-reported diagnosis of asthma. Patients were randomly divided into a training (n = 252) and validation (n = 109) set. For the analysis of eNose signals, principal component (PC) and linear discriminant analysis (LDA) were performed. LDA, based on PC1-4, reliably discriminated between patients who had a recent exacerbation from those who had not (training receiver operating characteristic (ROC)–area under the curve (AUC) = 0.76,95% CI 0.69–0.82), (validation AUC = 0.76, 95% CI 0.64–0.87). Our study showed that, exhaled breath analysis using eNose could accurately identify asthma patients who recently had an exacerbation, and could indicate that asthma exacerbations have a specific exhaled breath pattern detectable by eNose.

Breath analysis using eNose technology can be used to discriminate between asthma and COPD patients, but it remains unclear whether results are influenced by smoking status. We aim to study whether eNose can discriminate between ever- vs. never-smokers and smoking 24 h before the exhaled breath, and if smoking can be considered a confounder that influences eNose results. We performed a cross-sectional analysis in adults with asthma or chronic obstructive pulmonary disease (COPD), and healthy controls. Ever-smokers were defined as patients with current or past smoking habits. eNose measurements were performed by using the SpiroNose. The principal component (PC) described the eNose signals, and linear discriminant analysis determined if PCs classified ever-smokers vs. never-smokers and smoking 24 h. The area under the receiver–operator characteristic curve (AUC) assessed the accuracy of the models. We selected 593 ever-smokers (167 smoked <24 h before measurement) and 303 never-smokers and measured the exhaled breath profiles of discriminated ever- and never-smokers (AUC: 0.74; 95% CI: 0.66–0.81), and no cigarette consumption <24h (AUC 0.54, 95% CI: 0.43–0.65). In healthy controls, the eNose did not discriminate between ever or never-smokers (AUC 0.54; 95% CI: 0.49–0.60) and recent cigarette consumption (AUC 0.60; 95% CI: 0.50–0.69). The eNose could distinguish between ever and never-smokers in asthma and COPD patients, but not recent smokers. Recent smoking is not a confounding factor of eNose breath profiles.