Biomarkers in asthmatic patients: Has their time come to direct treatment?

Abstract

Asthma is a heterogeneous disease with multiple phenotypes that have variable risk factors and responses to therapeutics. Mild-to-moderate asthma often responds to traditional medications, whereas severe disease can be refractory to inhaled corticosteroids, long-acting β-agonists, and leukotriene receptor antagonists. There is robust research into the variable phenotypes of asthma. Biomarkers help define the specific pathophysiology of different asthma phenotypes and identify potential therapeutic targets. The following review will discuss the current use of biomarkers for the diagnosis of asthma, triaging the severity of a patient's disease, and the potential efficacy of treatments. This information can be used to define certain patient populations that are more likely to respond to inhaled corticosteroids or biologics. As knowledge of patient phenotypes and endotypes and biological agents to target specific classes of asthma emerge, the ability to provide personalized care to asthmatic patients will follow.

Improving the diagnosis of eosinophilic asthma

“…Processing requires time and expertise and results are not readily available. This has led to surrogates to detect airway eosinophilia including blood eosinophils, the fraction of exhaled nitric oxide (FeNO), serum periostin, and serum immunoglobulin E (IgE) [25]. Most of these markers have proven their use in clinical setting.…”

“…So, merely for the diagnosis of 'eosinophilic asthma,' one single measurement of blood eosinophils does not seem to be of great value. The most important role for blood eosinophils is probably its role in identifying patients who are likely to respond to treatment with the new biological agents against Type 2 inflammation [25]. However, they seem to be less suitable to monitor treatment response, given the fact that biologicals such as anti-IL-5 strongly reduce blood eosinophils but affect tissue eosinophils to a much lesser extent [28].…”

Endotypes of allergic diseases and asthma: An important step in building blocks for the future of precision medicine

“…For example, blood eosinophils predict response to anti-IL-4/IL-13, anti-IL-5, and anti-IgE antibodies, as well as CRTH2 antagonists and the clinician will face a challenge of how best to treat severe asthma patients with high blood eosinophils. 3,17 Precision medicine represents a novel approach, embracing four key features: personalized care based on molecular, immunologic and functional endotyping of the disease, with participation of the patient in the decision making process of therapeutic actions, and considering predictive and preventive aspects of the treatment. 1e3,19,20 Asthma, allergic rhinitis (AR), chronic rhinosinusitis (CRS), food allergy (FA) and atopic dermatitis (AD) are ideally suited for precision medicine, because they represent an umbrella of different diseases that partially share biological mechanisms (endotypes) and present similar visible properties (phenotypes) that require an individualized approach for a better selection of treatment responders, risk prediction and design of disease-modifying strategies.…”

Immune monitoring for precision medicine in allergy and asthma

“…Even if there are reproducible biological differences between subcategories of a disease, unless there are meaningful therapeutic options for each subcategory, or other advantages such as improved prognostication of the disease course, the clinical relevance of the classification will be questionable[4,37,38]. Validation of new classification schemes via testing of different therapies, such as monoclonal antibody drugs, will have major clinical and financial consequences for patients, and for companies developing novel therapies and “companion diagnostics” intended to evaluate whether a therapy would be effective in an individual patient.…”