Abstract Asthma is prevalent in the United States, affecting up approximately 8% of the population. Among asthmatic patients, up to 60% have poorly controlled asthma despite access to a variety of targeted medications. Eicosanoids are oxidized lipid signaling molecules, derived from arachidonic acid metabolism, and include cysteinyl leukotrienes, prostaglandins and thromboxanes, which play an important role in asthma pathogenesis. Pharmacological targeting of end-products of eicosanoid metabolism, primarily cysteinyl leukotrienes, results in modest benefits in asthma. In this application, we propose to test ROC-0929, a novel small molecule inhibitor that targets secreted phospholipase A2 group X or sPLA2-X. Phospolipases are key enzymes involved in the release of arachidonic acid from phospholipids and have other relevant functions including the release of other free fatty acids and lysophospholipids that serve as regulators of inflammation relevant to asthma. We have shown that sPLA2-X is the phospholipase that is most highly elevated in asthma and that genetic targeting of sPLA2-X is highly protective in a mouse pre-clinical model of asthma, using house dust mite (HDM) sensitization. We hypothesize that targeting sPLA2-X with a small molecule inhibitor will reduce immune responses and airway hyperresponsiveness (AHR). We will test this hypothesis, using a novel small molecule inhibitor, ROC-0929, in two relevant pre-clinical models of asthma and airway hyperresponsiveness. In the first aim, we will test the hypothesis that ROC-0929 alters intrinsic AHR to hyperpnea, using a guinea pig model. We will further test whether ROC-0929 inhibits features of persistent inflammation and indirect AHR in HDM sensitization, using guinea pigs. In the second aim, we will use a novel transgenic mouse in which the human sPLA2-X gene has been knocked into the murine Pla2g10 locus to determine whether ROC-0929 can mitigate features of airway dysfunction after the establishment of persistent airway inflammation by HDM exposure. At the conclusion of these proof-of-concept experiments, we anticipate sufficient data to support further development of an sPLA2-X inhibitor as a new therapeutic for asthma.