Person:

Wu, Ann

Aim: To identify the clinical and economic circumstances under which a pharmacogenomic test that predicts response to inhaled corticosteroids might be a cost-effective option for individuals with asthma.

Materials & methods: We synthesized published data on clinical and economic outcomes to project 10-year costs, quality-adjusted life-years and cost–effectiveness of pharmacogenomic testing for inhaled corticosteroid response. We assumed the pharmacogenomic test cost was $500 with a sensitivity and specificity of 84 and 98%, respectively. These were varied in sensitivity analyses.

Results: Both strategies, pharmacogenomic testing for inhaled corticosteroid response and no testing conferred 7.1 quality-adjusted life-years. Compared with no testing, pharmacogenomic testing costs less. Conclusion: Pharmacogenomic testing for asthma is cost-saving and noninferior in improving health.

Background: Single nucleotide polymorphisms (SNPs) influence a patient's response to inhaled corticosteroids and β2-agonists, and the effect of treatment with inhaled corticosteroids is synergistic with the effect of β2-agonists. We hypothesized that use of inhaled corticosteroids could influence the effect of SNPs associated with bronchodilator response.

Objective: To assess whether, among asthma subjects, the association of SNPs with bronchodilator response is different between those treated with inhaled corticosteroids vs. those on placebo.

Methods: A genome-wide association analysis was conducted using 581 white subjects from the Childhood Asthma Management Program (CAMP). Using data for 449,540 SNPs, we conducted a gene by environment analysis in PLINK with inhaled corticosteroid treatment as the environmental exposure and bronchodilator response as the outcome measure. We attempted to replicate the top 12 SNPs in the Leukotriene Modifier Or Corticosteroid or Corticosteroid-Salmeterol (LOCCS) Trial.

Results: The combined P-value for the CAMP and LOCCS populations was 4.81E-08 for rs3752120, which is located in the zinc finger protein gene ZNF432, and has unknown function.

Conclusions: Inhaled corticosteroids appear to modulate the association of bronchodilator response with variant(s) in the ZNF432 gene among adults and children with asthma.

Clinical Implications: Clinicians who treat asthma patients with inhaled corticosteroids should be aware that the patient's genetic makeup likely influences response as measured in lung function.

Capsule Summary: Our study suggests that inhaled corticosteroids could influence the effect of multiple SNPs associated with bronchodilator response across the genome.

Abstract Inhaled corticosteroids (ICS) are the most effective controller medications for asthma, and variability in ICS response is associated with genetic variation. Despite ICS treatment, some patients with poor asthma control experience severe asthma exacerbations, defined as a hospitalization or emergency room visit. We hypothesized that some individuals may be at increased risk of asthma exacerbations, despite ICS use, due to genetic factors. A GWAS of 237,726 common, independent markers was conducted in 806 Caucasian asthmatic patients from two population‐based biobanks: BioVU, at Vanderbilt University Medical Center (VUMC) in Tennessee (369 patients), and Personalized Medicine Research Project (PMRP) at the Marshfield Clinic in Wisconsin (437 patients). Using a case–control study design, the association of each SNP locus with the outcome of asthma exacerbations (defined as asthma‐related emergency department visits or hospitalizations concurrent with oral corticosteroid use), was evaluated for each population by logistic regression analysis, adjusting for age, gender and the first four principal components. A meta‐analysis of the results was conducted. Validation of expression of selected candidate genes was determined by evaluating an independent microarray expression data set. Our study identified six novel SNPs associated with differential risk of asthma exacerbations (P < 10−05). The top GWAS result, rs2395672 in CMTR1, was associated with an increased risk of exacerbations in both populations (OR = 1.07, 95% CI 1.03–1.11; joint P = 2.3 × 10−06). Two SNPs (rs2395672 and rs279728) were associated with increased risk of exacerbations, while the remaining four SNPs (rs4271056, rs6467778, rs2691529, and rs9303988) were associated with decreased risk. Three SNPs (rs2395672, rs6467778, and rs2691529) were present in three genes: CMTR1, TRIM24 and MAGI2. The CMTR1 mRNA transcript was significantly differentially expressed in nasal lavage samples from asthmatics during acute exacerbations, suggesting potential involvement of this gene in the development of this phenotype. We show that genetic variability may contribute to asthma exacerbations in patients taking ICS. Furthermore, our studies implicate CMTR1 as a novel candidate gene with potential roles in the pathogenesis of asthma exacerbations.