Abstract Idiopathic Pulmonary Fibrosis (IPF) is a rapidly progressing lung disease with no known cure. This therapeutic gap partly reflects the failure of current drug discovery technologies. A common weakness is that they do not provide a holistic assessment of a drug, largely due to the lack of direct evaluation of physiological endpoints relevant to patient wellbeing. Thus, drug candidates can potentially be missed, or hits might ultimately have little impact on patient wellbeing. We propose that parenchymal stiffness, a physical characteristic of tissue, is a suitable target. The reason is that lung stiffness governs ventilation at the macroscale and can drive cellular behaviors that promote and amplify IPF at the microscale. To measure macro- and micro-scale stiffness, we have recently invented a biomechanical method suitable for implementation in human precision cut lung slices (hPCLS). Using this method, our preliminary results show that the median and variance of IPF hPCLS stiffness was ~3 and 30-fold greater than healthy hPCLS, respectively. Empowered by this data, our central hypothesis is that the hPCLS stiffness map is well suited to evaluate whether a drug can therapeutically reduce, preemptively slow, and/or stop IPF progression. To test this hypothesis, we seek to: 1) integrate micro- with macro-scale stiffness measurements with traditional IPF discovery endpoints, and 2) demonstrate proof-of-concept in testing the therapeutic and preventive capabilities of IPF drugs. Aim 1: To establish that hPCLS stiffness can be used to evaluate the therapeutic capability of IPF drugs. We will achieve this by (1) improving stiffness maps to associate local stiffness with specific alveolar structures, and (2) correlating alveolar stiffening with microscale remodeling of alveolar architecture, collagen microstructure, and alpha smooth muscle actin. The measurements will be obtained before and 5 days after treating IPF-derived hPCLS with Nintedanib that reduces type III collagen production or Epigallocatechin Gallate that inhibits both lysyl oxidase (LOX, collagen cross-linking enzyme) and transforming growth factor β1 (TGF β1) kinase. Aim 2: To establish that hPCLS stiffness can be used to evaluate the preventive capability of IPF drugs. A key advantage of our approach is the ability to perform longitudinal and noninvasive assessment of hPCLS stiffness. We will take advantage of this unique capability to monitor spatiotemporal evolution of macro- and micro-scale stiffness together with fibrillar collagen deposition of each hPCLS over 7 days, in the presence or absence of a well-established pro-fibrotic cocktail. The experiments will be repeated after co-treating normal hPCLS samples with either Nintedanib or Epigallocatechin Gallate. Impacts: In this phase I application, we will develop a stiffness-based IPF drug discovery platform. In a Phase II follow- up, we will: 1) integrate the MechanoWell® with state-of-the-art multiomic approaches to bette...