Weiguo Han, Steven M. Keller, Olivier Loudig, Maria Katherine Fernandez, Yousin Suh, Saurabh Gombar, Ali Sadoughi, Kith Pradhan, H. Dean Hosgood, Kenny Ye, Miao Shi, Lizzet DeLaRosa, Taha Siddiqui, D. Patel, Chirag D. Shah, Tao Wang, Jay B. Dobkin, Changcheng Zhu, Robert E. Siegel, Aditi Desai, and Simon D. Spivack
Background: An exhaled microRNA-based lung cancer case-control discriminant biomarker strategy is reported.Methods: A microRNA-seq discovery effort compared paired tumor to non-tumor tissue, was reconciled with analogous TCGA and published literature-based tissue-discriminant microRNA data, yielding a candidate panel of 24 microRNAs that are upregulated in either adenocarcinomas and/or squamous cell carcinomas. The technical feasibility of microRNA-PCR assays in exhaled breath condensate (EBC) was tested. The airway origin of exhaled microRNAs was then topographically “fingerprinted”, using paired EBC and bronchoscopic samples. For initial EBC testing, a clinic-based case-control set of 351 individuals (166 NSCLC cases, 185 non-cancer controls) was interrogated with the 24-candidate microRNA panel by qualitative RT-PCR, and curated by melt curve analysis. Data were analyzed by both logistic regression (LR), and by random-forest (RF) models, validated by iterative resampling.Results: Both feasibility of exhaled microRNA detection, and its origins in part from lower airway sources, were confirmed. LR models adjusted for age, sex, smoking status, pack years, quit-years, and underlying lung disease identified exhaled miR-21, 33b, 212 (p.adj,=0.019, 0.018, 0.033, resp.) as case-control discriminant. For the RF analysis, the combined clinical + microRNA models showed modest added discrimination capacity (1.1–2.5%) beyond the clinical models alone: by subgroup, all subjects 1.1% (p = 8.7e-04)); former smokers 2.5% (p = 3.6e-05); early stage 1.2% (p = 9.0e-03). Sensitivity, specificity, positive- and negative-predictive values of the clinical + microRNA models for the entire cohort were 71%-76%.Conclusion: This work suggests that exhaled microRNAs are measurable qualitatively; reflect in part lower airway signatures; and if improved/refined, can potentially help distinguish lung cancer cases from controls.