BIOMARKER DISCOVERY LAB ABSTRACT Increases in the use of computed tomography (CT) for lung cancer (LC) screening and other indications has dramatically multiplied the detection of indeterminate pulmonary nodules (IPNs), resulting in a clinical management challenge. The estimated annual US prevalence of incidentally detected pulmonary nodules was 1.57 million persons. The number of nodules will continue to increase given the widespread use of CT and the new recommendations that expand the screen-eligible population for annual low-dose CT screening. In patients presenting with screen or incidentally detected IPNs, the goal is to rapidly identify and treat malignant nodules while avoiding unnecessary follow-up or invasive procedures. However, discriminating between benign and malignant nodules is challenging especially among intermediate-risk IPNs where the clinical management is the most variable and false positivity rates are high. There is an urgent and unmet need to develop biomarkers to better risk-stratify intermediate risk IPNs to improve and standardize clinical management. The focus of this Biomarker Discovery Lab (BDL) is to develop, refine, and validate non-invasive nasal gene expression, circulating tumor cell (CTC), and CT image-based biomarkers in both screen and incidentally detected IPNs of intermediate-risk. The goal of the BDL biomarkers is to transition a subset of intermediate-risk IPNs to 1) low- risk where they can be followed with CT surveillance or 2) high-risk where histologic sampling is commonly performed. We hypothesize that integrated biomarkers combining clinical, molecular, and imaging data as well as longitudinal measurement of biomarkers (during follow-up surveillance) will maximize the stratification of patients with intermediate-risk IPNs into these clinically actionable groups. To achieve our goals, we have partnered via the Biomarker Reference Lab with two industrial partners and an academic advanced image analysis laboratory. Each of the industrial partners have CLIA-LDT tests for early detection of lung cancer that will be further validated in the setting of intermediate-risk IPN and tested as longitudinal biomarkers in large and unique cohorts of screen and incidentally detected IPNs. The BDL collaboration is designed to meet the goal of significantly changing the risk stratification and clinical management of IPNs.