Evaluation of sputum eosinophil count as a predictor of treatment response to mepolizumab

Biomarker-driven drug development for allergic diseases and asthma: An FDA public workshop

The US Food and Drug Administration (FDA) hosted a workshop on February 22, 2024, to discuss the status of biomarkers in drug development for allergic asthma and food allergy. The workshop provided a forum for open discussion among regulators, academicians, National Institutes of Health staff and industry to inform stakeholders of the requirements for the FDA to adopt a biomarker as a surrogate end point for a clinical trial, and to inform FDA of the status of various biomarkers in development. The workshop was divided into 3 sessions: (1) FDA and European Union regulators discussing regulatory perspectives on use of biomarkers in drug development programs, (2) investigators discussing biomarkers for pediatric and adult asthma, and (3) investigators discussing biomarkers for food allergy. In this report, we review the information presented at the workshop and summarize the current status of potential biomarkers for these allergic diseases.

Type-2 Inflammation in Health and Disease: Prevalence, Risk Factors and Multimorbidity

Background: In patients with airflow obstruction, the levels of biomarkers of Type-2 (T2) inflammation serve to predict the effectiveness of inhaled corticosteroid and biological therapies. Elevated biomarkers of T2 inflammation, including fractional exhaled nitric oxide (FeNO, ≥20 ppb) and blood eosinophil counts (BEC, ≥300 cells/µL), were investigated in a population-based cohort of the Austrian LEAD study. Methods: A total of 4976 individuals (aged 18-82 years) were categorised into four groups based on their FeNO and BEC levels: normal with FeNO < 20 ppb and BEC < 300 cells/µL (n = 2634); FeNO ≥ 20 ppb only (n = 1623); BEC ≥ 300 cells/µL only (n = 340); and FeNO ≥ 20 ppb and BEC ≥ 300 cells/µL (n = 379). Results: In age- and sex-adjusted regression models, individuals with elevated BEC only were most associated with chronic cough and sputum production (odds ratios [95% CI]: 1.22 [0.78, 1.84] and 1.37 [1.13, 2.62], respectively), whilst individuals with both elevated T2 biomarkers were most associated with wheezing, dyspnoea and asthma (odds ratios [95% CI]: 2.27 [1.56, 3.26], 1.32 [0.64, 2.50] and 3.63 [2.69, 4.88] respectively). Elevated levels of both FeNO and BEC presented an additive effect in extrapulmonary conditions, particularly in allergy, eczema and rhino conjunctivitis (odds ratios [95% CI]: 2.30 [1.84, 2.88], 1.37 [1.03, 1.81] and 2.95 [2.34, 3.70], respectively). Conclusions: T2 inflammation marked by elevated levels of FeNO and/or BEC is not only associated with respiratory conditions but also extends to extrapulmonary characteristics, with an additive effect.

Breath and Sputum Analyses in Asthmatic Patients: An Overview

Recent advancements in asthma management include non-invasive methodologies such as sputum analysis, exhaled breath condensate (EBC), and fractional exhaled nitric oxide (FeNO). These techniques offer a means to assess airway inflammation, a critical feature of asthma, without invasive procedures. Sputum analysis provides detailed insights into airway inflammation patterns and cellular composition, guiding personalized treatment strategies. EBC collection, reflecting bronchoalveolar lining fluid composition, provides a non-invasive window into airway physiology. FeNO emerges as a pivotal biomarker, offering insights into eosinophilic airway inflammation and aiding in asthma diagnosis, treatment monitoring, and the prediction of exacerbation risks. Despite inherent limitations, each method offers valuable tools for a more comprehensive assessment of asthma. Combining these techniques with traditional methods like spirometry may lead to more personalized treatment plans and improved patient outcomes. Future research is crucial to refine protocols, validate biomarkers, and establish comprehensive guidelines in order to enhance asthma management with tailored therapeutic strategies and improved patient outcomes.

Pulmonology for the rhinologist

PURPOSE OF REVIEW

The upper and lower airways are inter-related despite serving different functions and can no longer be considered separately. Rhinologists are becoming increasingly aware of the role the lower airway plays in optimizing outcomes for their patients. This review highlights recent developments in pulmonology that impact rhinologic conditions.

RECENT FINDINGS

The unified airway concept now supports the multidisciplinary management of respiratory and rhinologic pathologies. Biomarkers, biologics and the concept of treatable traits have permitted the development of personalized and precise treatment of the entire respiratory tract. The concept of corticosteroid stewardship, the introduction of steroid sparing agents for the treatment of respiratory diseases and the development of biomarkers, now forces us to be more considerate and precise with oral corticosteroid (OCS) prescribing and to consider reduction regimens. Finally, current research on climate change and vaping will allow us to better educate and prepare our patients to improve adherence and avoid exacerbations to maintain optimal global respiratory health.

SUMMARY

The inter-relatedness of the upper and lower airway has encouraged a multidisciplinary focus in respiratory medicine. More research is required to improve the precision respiratory medicine model, particularly in the realm of biomarkers and endotyping. These developments must also consider the impact of climate change, pollution and toxins for us to provide optimum care for our patients.

Eosinophils-from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion

Over the past years, eosinophils have become a focus of scientific interest, especially in the context of their recently uncovered functions (e.g. antiviral, anti-inflammatory, regulatory). These versatile cells display both beneficial and detrimental activities under various physiological and pathological conditions. Eosinophils are involved in the pathogenesis of many diseases which can be classified into primary (clonal) and secondary (reactive) disorders and idiopathic (hyper)eosinophilic syndromes. Depending on the biological specimen, the eosinophil count in different body compartments may serve as a biomarker reflecting the underlying pathophysiology and/or activity of distinct diseases and as a therapy-driving (predictive) and monitoring tool. Personalized selection of an appropriate therapeutic strategy directly or indirectly targeting the increased number and/or activity of eosinophils should be based on the understanding of eosinophil homeostasis including their interactions with other immune and non-immune cells within different body compartments. Hence, restoring as well as maintaining homeostasis within an individual's eosinophil pool is a goal of both specific and non-specific eosinophil-targeting therapies. Despite the overall favourable safety profile of the currently available anti-eosinophil biologics, the effect of eosinophil depletion should be monitored from the perspective of possible unwanted consequences.

Super-responders to anti-IL-5/anti-IL-5R are characterised by high sputum eosinophil counts at baseline

Several clinical trials have demonstrated that anti-IL-5(R) biologics were able to improve lung function, asthma control and chronic oral corticosteroid exposure and reduce exacerbations among eosinophilic asthmatic patients. However, a certain variability in clinical responses to anti-IL-5(R) biologics was brought to light. Our study aimed at evaluating the role of baseline sputum eosinophils in identifying super-responders to mepolizumab and benralizumab. Our study reinforces the importance to examine sputum eosinophils in patients suffering from severe asthma before starting a biologic as it is associated with the intensity of response to mepolizumab and benralizumab.

Omalizumab Transitions in Severe Asthma: Factors Influencing Switching Decisions and Timing for Optimal Response

OBJECTIVE

The objective of this study was to assess the effectiveness of switching from omalizumab to another biologic therapy for patients with severe asthma and evaluate factors that influenced the decision to switch and determined the optimal time for a good biologic response.

SUBJECTS AND METHODS

A retrospective study of severe asthma patients was conducted at Al-Rashed Allergy Center, a tertiary center in Kuwait. After meeting the eligibility criteria, patients were divided into two comparative groups: those continuing with omalizumab and those who started with omalizumab but switched to another biologic.

RESULTS

One hundred sixteen patients with severe asthma were recruited, and only 33 had access to multiple biological treatments. Approximately 22.4% switched from omalizumab. Male patients with a history of ischemic heart disease, chronic rhinosinusitis, and nasal polyps were more likely to switch if they had higher levels of eosinophils in the sputum. This study showed that every 1% increase in sputum eosinophils doubled the likelihood of a switch. Patients with access to alternative biological options had a much shorter mean duration of omalizumab therapy before switching compared to those with only affordable omalizumab: 4.9 ± 1.5 years versus 8.9 ± 1.3 years (p < 0.001). The optimal time to predict the likelihood of a good response was less than 5.5 years, with an area under the curve of 0.91 and p = 0.003. This cutoff point provided a sensitivity and specificity of approximately 89% and 100%, respectively.

CONCLUSION

An early transition from omalizumab, specifically within the first 5 years of treatment, in patients with severe asthma and higher sputum eosinophils may enhance the likelihood of a good response if other biological therapies were available.

Personalized and Precision Medicine in Asthma and Eosinophilic Esophagitis: The Role of T2 Target Therapy

The role of type 2 inflammation has been progressively associated with many diseases, including severe asthma, atopic dermatitis, nasal polyposis, eosinophilic granulomatosis with polyangiitis, and, recently, eosinophilic esophagitis. Despite this, the association between asthma and esophagitis is still poorly known, and this is probably because of the low prevalence of each disease and the even lower association between them. Nonetheless, observations in clinical trials and, subsequently, in real life, have allowed researchers to observe how drugs acting on type 2 inflammation, initially developed and marketed for severe asthma, could be effective also in treating eosinophilic esophagitis. For this reason, clinical trials specifically designed for the use of drugs targeted to type 2 inflammation were also developed for eosinophilic esophagitis. The results of clinical trials are presently promising and envisage the use of biologicals that are also likely to be employed in the field of gastroenterology in the near future. This review focuses on the use of biologicals for type 2 inflammation in cases of combined severe asthma and eosinophilic esophagitis.

Upper airway disease diagnosis as a predictive biomarker of therapeutic response to biologics in severe asthma

Asthma is a heterogeneous disease sharing airway instability but with different biology, risk factors, and response-to-therapy patterns. Biologics have revolutionized the one-size-fits-to-all approach to personalized medicine in severe asthma (SA), which relies on the identification of biomarkers that define distinct endotypes. Thus, blood eosinophils and, to some extent, exhaled nitric oxide (FeNO) can predict the response to approved anti-type 2 (T2) biologics (anti-IgE, anti-IL-5, and anti-IL-4R alpha), whereas age at onset and comorbidities such as anxiety/depression, obesity, reflux, and upper airway disease (UAD) also influence therapeutic responses in SA. In this article, focusing on the predictive value of biomarkers for the therapeutic response to biologics in SA, we first summarize the level of prediction achieved by T2 biomarkers (blood eosinophils, FeNO) and then review whether data support the predictive value of upper airway diagnosis on such outcomes. Post hoc analysis of most studies with T2 biologics suggests that chronic rhinosinusitis with nasal polyps (CRSwNP) and, to a lower extent, allergic rhinitis may help in predicting clinical response. Considering that T2 biologics are now also approved for the treatment of severe CRSwNP, diagnosis of upper airway disease is a key step in determining eligibility for such therapy.

Galectin-10 as a Potential Biomarker for Eosinophilic Diseases

Galectin-10 is a member of the lectin family and one of the most abundant cytoplasmic proteins in human eosinophils. Except for some myeloid leukemia cells, basophils, and minor T cell populations, galectin-10 is exclusively present in eosinophils in the human body. Galectin-10 forms Charcot–Leyden crystals, which are observed in various eosinophilic diseases. Accumulating studies have indicated that galectin-10 acts as a new biomarker for disease activity, diagnosis, and treatment effectiveness in asthma, eosinophilic esophagitis, rhinitis, sinusitis, atopic dermatitis, and eosinophilic granulomatosis with polyangiitis. The extracellular release of galectin-10 is not mediated through conventional secretory processes (piecemeal degranulation or exocytosis), but rather by extracellular trap cell death (ETosis), which is an active cell death program. Eosinophils undergoing ETosis rapidly disintegrate their plasma membranes to release the majority of galectin-10. Therefore, elevated galectin-10 levels in serum and tissue suggest a high degree of eosinophil ETosis. To date, several studies have shown that galectin-10/Charcot–Leyden crystals are more than just markers for eosinophilic inflammation, but play functional roles in immunity. In this review, we focus on the close relationship between eosinophils and galectin-10, highlighting this protein as a potential new biomarker in eosinophilic diseases.

Recent insights in the role of biomarkers in severe asthma management

Contemporary asthma management requires a proactive and individualized approach, combining precision diagnosis and personalized treatment. The introduction of biologic therapies for severe asthma to everyday clinical practice, increases the need for specific patient selection, prediction of outcomes and monitoring of these costly and long-lasting therapies. Several biomarkers have been used in asthma in disease identification, prediction of asthma severity and prognosis, and response to treatment. Novel advances in the area of personalized medicine regarding disease phenotyping and endotyping, encompass the development and application of reliable biomarkers, accurately quantified using robust and reproducible methods. The availability of powerful omics technologies, together with integrated and network-based genome data analysis, and microbiota changes quantified in serum, body fluids and exhaled air, will lead to a better classification of distinct phenotypes or endotypes. Herein, in this review we discuss on currently used and novel biomarkers for the diagnosis and treatment of asthma.