A high throughput screen to identify broad-spectrum, mold-active antifungals

About This Grant

PROJECT SUMMARY Invasive mold infections (IMIs) are a major cause of morbidity and mortality among susceptible populations worldwide. Risk factors for IMIs include immunomodulatory therapies such as chemotherapy, long- term corticosteroid use, viral infections, and diabetic ketoacidosis. IMIs are caused by a handful of environmental molds, but the most common are Aspergillus fumigatus and Zygomycetes, including Mucor and Rhizopus spp. Currently, there are three classes of antifungals used to treat IMIs; however, despite available treatments, mortality rates are typically ~50% but reach 80-100% for some mold species and patient cohorts. A major challenge in treating IMIs is lack of efficacy of current antifungals against molds due to intrinsic and acquired resistance of mold species to clinical antifungals. To address the need for mold-active antifungals, we developed and validated a resazurin-based screening assay to screen directly with the Zygomycete Mucor circinelloides, representing the first high throughput screen against a non-Aspergillus mold. In Aim 1A, we will utilize this assay to screen 150,000 drug like molecules. Our primary hits will be prioritized in Aim 1B to identify those with broad spectrum activity and acceptable in vitro mammalian toxicity. Next, in Aim 1C, we will test the bioavailability of each compound with murine pharmacokinetic studies to identify the best candidates for in vivo use. In Aim 2, we will narrow our focus to one scaffold that will be subject to mechanism-driven SAR studies. We will utilize several approaches to define the mode and mechanism of action including chemical genomics, phenotyping and generation of resistant mutants. Iterative rounds of chemical optimization and compound testing will enable identification of potent antifungal molecules with limited toxicity. Finally, in Aim 3, the top compounds from our optimized series will be tested in murine models of fungal disease including disseminated mucormycosis. The completion of this award will result in a novel, mold-active compound for IND-enabling studies for the treatment of life-threatening IMIs.