Monitoring response to treatment in asthma management: food for thought

Biomarkers for severe allergic asthma in children: could they be useful to guide disease control and use of omalizumab?

INTRODUCTION

Although symptom controls in asthmatic children can be achieved through compliant use of conventional medication, some children have uncontrolled severe persistent asthma, especially if they are allergic. For these children, omalizumab (approved by the EMA and FDA in children aged > 6 years) could be a therapeutic option. However, response to omalizumab varies from one child to another. Predictive biomarkers of omalizumab effectiveness could be useful to monitor response to treatment. Area covered: The authors searched in the PubMed database for publications related to the use of biomarkers in allergic asthma. Supported by their own experience in phenotyping asthma in children, they analyzed whether these biomarkers could be useful in assessing response to omalizumab. Expert commentary: Th2 inflammation in children with allergic asthma can be assessed by measuring several biomarkers (blood eosinophil, serum ECP or periostin, FeNO). While a single measurement may be insufficient, a combination of biomarkers assessments may improve the follow-up of children treated by omalizumab.

The clinician's guide on monitoring children with asthma

Based on a review of the evidence on the usefulness of monitoring disease outcome parameters in childhood asthma and the author's 20-yr clinical experience in managing childhood asthma, this article provides the clinician with up-to-date recommendations on how to monitor childhood asthma in everyday clinical practice. Monitoring should be focused on patient-centered outcomes, such as exacerbations and impact on sports and play. Composite asthma control measures, although reasonably validated, do not take exacerbations into account and have a short recall window, limiting their usefulness as a routine monitoring tool in clinical practice. Lung function, airways hyperresponsiveness, exhaled nitric oxide, and inflammatory markers in sputum are surrogate end points, of little if any interest to patients. There is no evidence to support their use as a monitoring tool in clinical practice; office spirometry may be used as additional information. Rather than monitoring surrogate end points, clinicians should focus on showing a genuine interest in the impact of asthma on children's daily lives, and building and maintaining a partnership by monitoring those characteristics of asthma which have the biggest impact on children (exacerbations and limitations in sports and play), and adjusting treatment accordingly.

The metabolomics of asthma: novel diagnostic potential

Asthma is one of the most common chronic illnesses, especially in children. Reaching the diagnosis of asthma and its management are more difficult than for other chronic illnesses. For example, asthma is a heterogeneous syndrome with many clinical classifications based on patient symptoms, lung function, and response to therapy. The symptoms and objective measurements of lung function, often used to guide therapy, are largely based on the inflammation of the airways. Because measuring airway dysfunction and inflammation in a typical clinical setting is difficult, it is often not done. Metabolomics is the study of small molecules generated from cellular metabolic activity. It is possible that the metabolic profile of a patient with a chronic illness such as asthma is different from that of a healthy patient or from a patient with another respiratory illness. Furthermore, if this metabolome could be measured, it might also vary with disease severity. The pattern of metabolites becomes the diagnostic representing the disease. This article outlines the more recent work that has been done to develop the metabolomic profile of asthma.

Metabolomic profiling of asthma: diagnostic utility of urine nuclear magnetic resonance spectroscopy

BACKGROUND

The ability to diagnose and monitor asthma on the basis of noninvasive measurements of airway cellular dysfunction is difficult in the typical clinical setting.

OBJECTIVE

Metabolomics is the study of molecules created by cellular metabolic pathways. We hypothesized that the metabolic activity of children with asthma would differ from healthy children without asthma. Furthermore, children having an asthma exacerbation would be different compared with children with stable asthma in outpatient clinics. Finally, we hypothesized that (1)H-nuclear magnetic resonance (NMR) would measure such differences using urine samples, one of the least invasive forms of biofluid sampling.

METHODS

Children (135 total, ages 4-16 years) were enrolled, having met the criteria of healthy controls (C), stable asthma in the outpatient clinic (AO), or unstable asthma in the emergency department (AED). Partial least squares discriminant analysis was performed on the NMR data to create models of separation (70 metabolites were measured/urine sample). Some NMR data were withheld from modeling to be run blindly to determine possible diagnostic accuracy.

RESULTS

On the basis of the model of AO versus C, 31 of 33 AO samples were correctly diagnosed with asthma (94% accuracy). Only 1 of 20 C samples was incorrectly labeled as asthma (5% misclassification). On the basis of the AO versus AED model, 31 of the 33 AO samples were correctly diagnosed as outpatient asthma (94% accurate).

CONCLUSION

This is the first report suggesting that (1)H-NMR analysis of human urine samples has the potential to be a useful clinical tool for physicians treating asthma.

Endpoints in respiratory diseases

A wide range of outcome measures or endpoints has been used in clinical trials to assess the effects of treatments in paediatric respiratory diseases. This can make it difficult to compare treatment outcomes from different trials and also to understand whether new treatments offer a real clinical benefit for patients. Clinical trials in respiratory diseases evaluate three types of endpoints: subjective, objective and health-related outcomes. The ideal endpoint in a clinical trial needs to be accurate, precise and reliable. Ideally, the endpoint would also be measured with minimal risk and across all ages, easy to perform, and be inexpensive. As for any other disease, endpoints for respiratory diseases must be viewed in the context of the important distinction between clinical endpoints and surrogate endpoints. The association between surrogate endpoints and clinical endpoints must be clearly defined for any disease in order for them to be meaningful as outcome measures. The most common endpoints which are used in paediatric trials in respiratory diseases are discussed. For practical purposes, diseases have been separated into acute (bronchiolitis, acute viral-wheeze, acute asthma and croup) and chronic (asthma and cystic fibrosis). Further development of endpoints will enable clinical trials in children with respiratory diseases with the main objective of improving prognosis and safety.

Tumor necrosis factor-alpha in severe corticosteroid-refractory asthma

Tumor necrosis factor (TNF)-alpha is a proinflammatory cytokine. Blocking TNF-alpha has been demonstrated to be effective in various diseases, including both rheumatoid and psoriatic arthritis. There is evidence to show that levels of TNF-alpha are elevated in patients with severe asthma. TNF-alpha is involved in the initiation and perpetuation of the inflammatory process, epithelial damage and remodeling, and mucin hypersecretion. Furthermore, TNF-alpha polymorphism has also been reported in the asthmatic population. Based on the necessity for alternative treatments for asthmatics with severe disease and those who are particularly resistant to conventional asthma therapy, it has been shown that molecules targeted at blocking the effects of TNF-alpha probably constitute a considerable advance in the management of these difficult patients. This review focuses on the evidence of TNF-alpha axis upregulation in severe corticosteroid-refractory asthma, as well as the role of TNF-alpha inhibition and the adverse effects of treatment.

Control of asthma

Control is the aim of asthma management and clinical trials show that control can be achieved in the majority of patients. However, population surveys show that poorly controlled asthma still imposes a considerable burden. This fact has led to a re-evaluation of the international asthma guidelines and the updated 2006 and 2007 GINA and NAEPP guidelines suggest that the level of control should be used as the key feature for the classification and management of asthma. Furthermore, in the latest guidelines, a clearer definition of control is given and new tools for the assessment and monitoring of control are instituted. In order to achieve asthma control, not only relevant pharmacological treatment but, the establishment of a good patient-doctor relationship, proper education of the asthmatic patient, reduction of exposure to triggers and treatment of co-morbidities are pivotal issues and must be ensured.

Critical appraisal of antileukotriene use in asthma management

PURPOSE OF REVIEW

Recognition of the importance of leukotrienes in the pathogenesis of asthma has led to the development of leukotriene modifiers, the first new class of drugs for asthma treatment to become available since the introduction of inhaled corticosteroids. Nevertheless, despite their widespread use in clinical practice, the role of leukotriene modifiers in the management of asthma remains controversial. In the present article the clinical applications of this class of drugs have been critically reviewed based on recent evidence.

RECENT FINDINGS

In an effort to try and establish the proper place of antileukotrienes in the management of asthma, important systematic reviews have been carried out over these recent years in three critical areas: antileukotrienes as second choice first line agents after inhaled corticosteroids; antileukotrienes as add-on therapy to inhaled corticosteroids; add-on antileukotrienes versus long acting beta-agonists to patients not controlled by inhaled corticosteroids. In addition, novel and useful clinical targets for this class of drugs have been recently explored and include: patients with severe asthma; aspirin-intolerant asthma; asthmatic patients with allergic rhinitis.

SUMMARY

Use of antileukotrienes is not recommended as first-line monotherapy in patients with asthma, except those who have aspirin intolerant asthma. Patients with concomitant allergic rhinitis may be a good target population for therapy with antileukotrienes. Addition of leukotriene modifiers to inhaled corticosteroids produces only a modest improvement in the clinical response, and is not greater to that of add-on long acting beta-agonists. The exact role of antileukotrienes in asthma management guidelines still continues to evolve.

Adenosine receptors: promising targets for the development of novel therapeutics and diagnostics for asthma

Interest in the role of adenosine in asthma has escalated considerably since the early observation of its powerful bronchoconstrictor effects in asthmatic but not normal airways. A growing body of evidence has emerged in support of a proinflammatory and immunomodulatory role for the purine nucleoside adenosine in the pathogenic mechanisms of chronic inflammatory disorders of the airways such as asthma. The fact that adenosine enhances mast cell allergen-dependent activation, that elevated levels of adenosine are present in chronically inflamed airways, and that adenosine given by inhalation cause dose-dependent bronchoconstriction in subjects with asthma emphasizes the importance of adenosine in the initiation, persistence and progression of these common inflammatory disorders of the airways. These distinctive features of adenosine have been recently exploited in the clinical and research setting to identify innovative diagnostic applications for asthma. In addition, because adenosine exerts its multiple biological activities by interacting with four adenosine receptor subtypes, selective activation or blockade of these receptors may lead to the development of novel therapies for asthma.

Beclomethasone dipropionate attenuates airways hyperresponsiveness to neurokinin A and histamine in asthma

BACKGROUND

Inhaled corticosteroids (ICS) are the most effective anti-inflammatory agents available for the treatment of asthma but they produce only modest effects on airway inflammation and non-specific bronchial hyperresponsiveness (BHR). However, little is known about the possibility that treatment with ICS might cause additional protection on BHR to inhaled tachykinins such as neurokinin A (NKA).

OBJECTIVE

Therefore, we compared the effects of beclomethasone dipropionate (BDP) on the degree of BHR to inhaled histamine and NKA in a double-blind, controlled, cross-over study of asthmatic patients.

METHODS

Patients attended the laboratory before and after each 6 weeks treatment period to undertake concentration-response studies with histamine and NKA. Bronchial responsiveness to both funs was expressed as the provocative concentration producing a 20% decrease in FEV(1) from baseline (PC(20)).

RESULTS

BDP therapy attenuated the constrictor response to both agonists to a similar degree, their geometric mean (range) PC(20) values increasing from 0.47 (0.21-1.41) mg/ml to 2.43 (0.51-4.50) mg/ml (P<0.01, post-salb vs. post-BDP treatment) and from 101.7 (27.3-356.1) microg/ml to 666.7 (151.5-1,000) microg/ml (P<0.01, post-salb vs. post-BDP treatment) for histamine and NKA, respectively.

CONCLUSION

Airway responsiveness to histamine and NKA is reduced by BDP to the same extent. As a result of these findings, provocation with NKA is unlikely to provide additional useful information in the assessment of airway inflammation in asthma.

TNF-alpha as a promising therapeutic target in chronic asthma: a lesson from rheumatoid arthritis

TNF-alpha (tumour necrosis factor-alpha) is known to play a critical role in the pathogenic mechanisms of a number of chronic inflammatory diseases, including RA (rheumatoid arthritis), Crohn's disease and psoriasis. The notion that TNF-alpha is released in allergic responses from both mast cells and macrophages via IgE-dependent mechanisms, the demonstration that elevated levels of TNF-alpha are frequently observed in bronchoalveolar fluid of asthmatic subjects undergoing allergen challenge and the results from exposure studies of TNF-alpha in vivo showing increases in airway responsiveness in both normal and asthmatic subjects emphasize the importance of TNF-alpha in the initiation of allergic asthmatic airway inflammation and the generation of airway hyper-responsiveness. Drugs targeting TNF-alpha have been developed to neutralize the deleterious effects of this inflammatory cytokine and have proved to be safe and effective in the treatment of patients with RA, Crohn's disease and psoriasis refractory to conventional treatments. Biological therapies blocking TNF-alpha are likely to constitute a considerable advance in the management of those difficult cases of asthma that are particularly resistant to typical treatment modalities. In this review article, we intend to address the potential role of TNF-alpha in asthma and to put forward the idea that drugs that have been developed to neutralize the deleterious effects of TNF-alpha may also be useful in the management of chronic severe asthma.