Initial development and testing of an exhaled microRNA detection strategy for lung cancer case-control discrimination.

For detecting field carcinogenesis non-invasively, early technical development and case-control testing of exhaled breath condensate microRNAs was performed. In design, human lung tissue microRNA-seq discovery was reconciled with TCGA and published tumor-discriminant microRNAs, yielding a panel of 24 upregulated microRNAs. The airway origin of exhaled microRNAs was topographically "fingerprinted", using paired EBC, upper and lower airway donor sample sets. A clinic-based case-control study (166 NSCLC cases, 185 controls) was interrogated with the microRNA panel by qualitative RT-PCR. Data were analyzed by logistic regression (LR), and by random-forest (RF) models. Feasibility testing of exhaled microRNA detection, including optimized whole EBC extraction, and RT and qualitative PCR method evaluation, was performed. For sensitivity in this low template setting, intercalating dye-based URT-PCR was superior to fluorescent probe-based PCR (TaqMan). In application, adjusted logistic regression models identified exhaled miR-21, 33b, 212 as overall case-control discriminant. RF analysis of combined clinical + microRNA models showed modest added discrimination capacity (1.1-2.5%) beyond clinical models alone: all subjects 1.1% (p = 8.7e-04)); former smokers 2.5% (p = 3.6e-05); early stage 1.2% (p = 9.0e-03), yielding combined ROC AUC ranging from 0.74 to 0.83. We conclude that exhaled microRNAs are qualitatively measureable, reflect in part lower airway signatures; and when further refined/quantitated, can potentially help to improve lung cancer risk assessment.

Antitussive effect of the leukotriene receptor antagonist zafirlukast in subjects with cough-variant asthma.

Cough-variant asthma (CVA) occurs in a subgroup of asthmatics whose sole or predominant respiratory symptom is cough. Although bronchodilators are often sufficient to treat CVA, refractory cough may require therapy with inhaled or systemic corticosteroids. In a randomized, double-blind, placebo-controlled, crossover study, we examined the effect of a 14-day course of the leukotriene receptor antagonist zafirlukast on subjective cough score and cough-reflex sensitivity to inhaled capsaicin in eight subjects with CVA refractory to inhaled beta agonists, and in five subjects refractory to inhaled corticosteroids. Seven of eight subjects experienced significant subjective and objective improvement in cough after treatment with zafirlukast. Mean (+/- SEM) cough score improved from 7.75 +/- 0.56 to 3.25 +/- 0.84 (p = 0.0006). Cough sensitivity to capsaicin was suppressed by zafirlukast in all subjects. Patients with CVA may represent a distinct subgroup of asthmatics whose afferent cough receptors within the respiratory epithelium are hypersensitive relative to those of patients with the typical form of asthma. Zafirlukast appears to be particularly effective in treating CVA by inhibiting the sensitivity of these receptors. Leukotriene receptor antagonists may offer an alternative to corticosteroids for the treatment of CVA refractory to inhaled bronchodilators.