Personalized medicine for patients with asthma

Predictors of response to tiotropium versus salmeterol in asthmatic adults

BACKGROUND

Tiotropium has activity as an asthma controller. However, predictors of a positive response to tiotropium have not been described.

OBJECTIVE

We sought to describe individual and differential responses of asthmatic patients to salmeterol and tiotropium when added to an inhaled corticosteroid, as well as predictors of a positive clinical response.

METHODS

Data from the double-blind, 3-way, crossover National Heart, Lung, and Blood Institute's Asthma Clinical Research Network's Tiotropium Bromide as an Alternative to Increased Inhaled Glucocorticoid in Patients Inadequately Controlled on a Lower Dose of Inhaled Corticosteroid (ClinicalTrials.gov number, NCT00565266) trial were analyzed for individual and differential treatment responses to salmeterol and tiotropium and predictors of a positive response to the end points FEV1, morning peak expiratory flow (PEF), and asthma control days (ACDs).

RESULTS

Although approximately equal numbers of patients showed a differential response to salmeterol and tiotropium in terms of morning PEF (n = 90 and 78, respectively) and ACDs (n = 49 and 53, respectively), more showed a differential response to tiotropium for FEV1 (n = 104) than salmeterol (n = 62). An acute response to a short-acting bronchodilator, especially albuterol, predicted a positive clinical response to tiotropium for FEV1 (odds ratio, 4.08; 95% CI, 2.00-8.31; P < .001) and morning PEF (odds ratio, 2.12; 95% CI, 1.12-4.01; P = 0.021), as did a decreased FEV1/forced vital capacity ratio (FEV1 response increased 0.39% of baseline for every 1% decrease in FEV1/forced vital capacity ratio). Higher cholinergic tone was also a predictor, whereas ethnicity, sex, atopy, IgE level, sputum eosinophil count, fraction of exhaled nitric oxide, asthma duration, and body mass index were not.

CONCLUSION

Although these results require confirmation, predictors of a positive clinical response to tiotropium include a positive response to albuterol and airway obstruction, factors that could help identify appropriate patients for this therapy.

Asthma treatment outcome in children is associated with vascular endothelial growth factor A (VEGFA) polymorphisms

BACKGROUND

Asthma is a common chronic disease characterized by airway inflammation and structural remodeling. Vascular endothelial growth factor (VEGF), a major regulator of angiogenesis, is elevated in asthma patients. VEGF contributes to airway responsiveness and remodeling. It has been shown that treatment of asthma patients decreases VEGF levels, and inhibition of VEGF diminishes asthma symptoms in mice. Therefore, polymorphisms in the vascular endothelial growth factor A (VEGFA) gene might be associated with asthma treatment response.

METHODS

This study enrolled 131 children with asthma treated with different therapies - specifically, the inhaled corticosteroid (ICS) fluticasone propionate or the leukotriene receptor antagonist (LTRA) montelukast. We performed an association analysis between improvement of lung function - assessed by measurement of the percentage of the predicted forced expiratory volume in 1 second (%predicted FEV(1)), the ratio between the FEV(1) and the forced vital capacity (FEV(1)/FVC) after 6 and 12 months of treatment, and asthma control after 12 months of treatment - and two polymorphisms, rs2146323 and rs833058, in the VEGFA gene.

RESULTS

Polymorphism rs2146323 A>C in VEGFA was associated with response to ICS therapy. Asthma patients with the AA genotype had a greater improvement in the %predicted FEV(1) than those with the AC or CC genotype (p = 0.018). Conversely, the AA genotype in rs2146323 was associated with uncontrolled asthma in patients regularly receiving LTRA therapy (p = 0.020) and a worse FEV(1)/FVC ratio in patients who episodically used LTRA therapy (p = 0.044). Furthermore, polymorphism rs833058 C>T was associated with treatment response to episodically used LTRA therapy. A subgroup of patients with the TT genotype had an improvement in the %predicted FEV(1), compared with no improvement in patients with the CT or CC genotype (p = 0.029).

CONCLUSIONS

Our results showed that treatment response to commonly used asthma therapies (ICS or LTRA) is associated with polymorphisms rs2146323 and rs833058 in VEGFA. With additional replication of this preliminary study, our findings could contribute to the development of individualized asthma therapy.

The sentinel role of the airway epithelium in asthma pathogenesis

The adoption of the concept that asthma is primarily a disease most frequently associated with elaboration of T-helper 2 (Th2)-type inflammation has led to the widely held concept that its origins, exacerbation, and persistence are allergen driven. Taking aside the asthma that is expressed in non-allergic individuals leaves the great proportion of asthma that is associated with allergy (or atopy) and that often has its onset in early childhood. Evidence is presented that asthma is primarily an epithelial disorder and that its origin as well as its clinical manifestations have more to do with altered epithelial physical and functional barrier properties than being purely linked to allergic pathways. In genetically susceptible individuals, impaired epithelial barrier function renders the airways vulnerable to early life virus infection, and this in turn provides the stimulus to prime immature dendritic cells toward directing a Th2 response and local allergen sensitization. Continued epithelial susceptibility to environmental insults such as viral, allergen, and pollutant exposure and impaired repair responses leads to asthma persistence and provides the mediator and growth factor microenvironment for persistence of inflammation and airway wall remodeling. Increased deposition of matrix in the epithelial lamina reticularis provides evidence for ongoing epithelial barrier dysfunction, while physical distortion of the epithelium consequent upon repeated bronchoconstriction provides additional stimuli for remodeling. This latter response initially serves a protective function but, if exaggerated, may lead to fixed airflow obstruction associated with more severe and chronic disease. Dual pathways in the origins, persistence, and progression of asthma help explain why anti-inflammatory treatments fail to influence the natural history of asthma in childhood and only partially does so in chronic severe disease. Positioning the airway epithelium as fundamental to the origins and persistence of asthma provides a rationale for pursuit of therapeutics that increase the resistance of the airways to environmental insults rather than concentrating all effort on suppressing inflammation.

A call for action: Comparative effectiveness research in asthma

Comparative effectiveness research (CER) has received considerable research attention in recent months, and efforts to promote CER are part of the newly enacted Patient Protection and Affordable Care Act. In this article we define CER and how it complements traditional efficacy research in asthma and discuss how CER can help provide the basis for rational decision making about the care of individual patients with asthma and how best to deliver this care in real-world settings. We present information about the challenges and opportunities to conduct CER, including enhanced patient registries for observational CER and effectiveness trials (also called pragmatic trials). We discuss the urgent need to define the appropriate methodologies for CER and to develop and prioritize a research agenda for CER studies in asthmatic subjects with the help of a diverse group of stakeholders.