The National Cancer Institute has a need for development, standardization, and validation of assays that can quickly and cheaply determine or predict organ-specific toxicities of potential cancer therapeutic agents. The objective of the proposed project is to develop an in vitro lung cell assay to determine or predict potential dose-limiting pulmonary injury by anticancer agents in humans. Research in the R21 phase will focus on the development, evaluation, and optimization of one or more primary multicell systems that can meet that objective, in particular precision-cut lung slices and co-cultures of lung endothelial and epithelial cells. The assay to be developed will ultimately be able to discriminate between the major types of injury induced in lung by anticancer agents, differences in toxic potency, and interspecies differences in sensitivity. In this work, known and novel indicators will be investigated for assessing the degree and nature of the injury produced by the agents in vitro for correspondence with in vivo response, using the rat as a model and clinical chemistry and advanced proteomic and laser-MS (Jet-REMPI) techniques. Reference compounds used to develop and validate the assay will be anticancer agents with specific, well- defined, representative toxicities in animals and humans. The R33 phase will focus on developing the full capabilities of the assay as an important and critical part of the in vitro toxicity test battery needed by the NCI to screen for target organ toxicities and to aid in predicting safe dose levels and regimens for clinical trials.