Coccidioidomycosis, more commonly known as Valley Fever (VF), is an invasive fungal infection that is endemic to the warm, dry climate found in the Southwestern United States, Infection occurs when airborne spores of the pathogen enter the lungs. The estimated annual incidence of this illness in the U.S. is about 150,000 cases per year. Although about 60% of coccidioidomycosis cases are asymptomatic, the remaining 40% of patients manifest symptoms including self-limiting sore throat, fever, cough, fatigue, and chest pain, with some patients progressing to debilitating, life-threatening disseminated disease. The self-limiting symptoms can persist for weeks or months resulting in a substantial morbidity cost due to work lost and the costs of follow-up physician appointments. Moreover, the annual economic burden in California alone from hospitalizations due to coccidioidomycosis is on average about $190 million and the associated mortality rate for those patients hospitalized is 8%. Recently, Amplyx Pharmaceuticals has in-licensed the entire portfolio of potent Gwt1 inhibitors from Eisai. Several of these compounds show 1) good potency (M100 ? 0.13 g/mL) vs. both C. immitis and C. posadasii; 2) over 45% orally bioavailability in mouse and rat models; 3) low potential for drug-drug interactions based on in vitro P450 assays; 4) no observable toxicity at plasma levels in rodents that should permit strong antifungal activity; and 5) strong i vivo efficacy data. We plan to leverage the extensive structure- activity relationships (SAR) elucidated by the chemistry team at Eisai to refine the properties of our hit compounds employing the following Specific Aims: Aim 1. Create a first generation library of at least 25 analogues of hit compounds from Phase I. Aim 2. Characterize and select compounds for advancement by employing in vitro assays to assess 2a) antifungal potency; 2b) target engagement; 2c) cytotoxicity; 2d-2i) in vitro PK/PD. Aim 3. Characterize and select compounds for advancement by employing in vivo studies to assess a) PK; b) maximum tolerated dose; c) reduction of fungal burden; d) improved survival in VF models.