Optimized Synthetic Flavonols Support Senescence Clearance and Lung Fibrosis Resolution

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease with undefined etiology and minimally effective therapies. The greatest risk factor for developing IPF is aging. The central paradigm to developing antifibrotic drugs for the last half century has focused on directly targeting proliferative lung fibroblasts. However, recent high-resolution analyses of IPF patient lungs suggests disease unique populations of resident lung cells are enriched for markers of senescence. Published work by our group and others further supports that senescent cells are key drivers of fibrosis and may provide an opportunity to develop an effective antifibrotic drug. Multiple naturally derived flavonoids can selectively induce apoptosis in senescent cells (senolytic) and improve end points in models of lung fibrosis; however, these natural phytochemicals are not structurally optimized to maximize their translational potential. Inspired by this opportunity we have performed hit-to-lead studies and medicinal chemistry optimization to generate a novel synthetic flavanoid (F-4N) with ∼ 50× greater senolytic potency in vitro- compared to fisetin or quercetin, two naturally derived senolytic flavonols. Furthermore, in bleomycin injury models of lung fibrosis we have shown treatment with F-4N (10 mg/kg-30 mg/kg, daily) promotes reduced senescence burden, resolution of chronic lung fibrosis, and markers of enhanced alveolar epithelial repair.