Dual-Activity Inhibitors Targeting Aspergillus fumigatus PanK for Antifungal Therapy

About This Grant

Research Summary Invasive aspergillosis (IA), primarily caused by Aspergillus fumigatus, is a life-threatening infection that predominantly affects immunocompromised individuals. Despite advancements in antifungal treatments, IA is associated with high mortality rates; for instance, among solid organ transplant recipients, mortality rates range from 65% to 92%, with IA contributing to approximately 9.3%–16.9% of all deaths within the first-year post- transplantation. A. fumigatus is also an important cause of fungal keratitis (FK), a site-threatening corneal infection that occurs in otherwise healthy patients that experience corneal trauma. As with IA, visual outcomes associated with FK are also poor, with 70% of all patients experiencing reduced or complete loss of vision in the affected eye. These statistics underscore the urgent need for novel therapeutic strategies for both pulmonary and corneal A. fumigatus infection. Pantothenate kinases are essential enzymes involved in the biosynthesis of coenzyme A (CoA and Acetyl-CoA (AcCoA) (The PCA pathway). Our studies have demonstrated that inhibition of PanK activity and the PCA pathway not only impedes fungal growth but also disrupts vacuolar function, compromising the pathogen's ability to detoxify antifungal agents. This dual mechanism suggests that PanK inhibitors can serve both as standalone drugs and as potentiators of existing antifungal drugs. We previously screened a library of 256,000 compounds against A. fumigatus AfPanK and identified pyrimidone triazoles (PTZs) as potent and selective inhibitors of this essential enzyme. Using structure-activity relationship (SAR) studies we designed and synthesized a focused library of 113 PTZ analogs. The goal of this R21/R33 proposal is to evaluate the biochemical activity, pharmacological properties and in vitro and in vivo efficacy of these compounds and identify potent dual-activity PTZ molecules to develop as novel antifungal agents against A. fumigatus infection. In the R21 phase, we will screen this focused library of PTZ analogs against purified AfPanK and a CDC collection of drug-sensitive and -resistant A. fumigatus clinical isolates. Potent candidate inhibitors will be further evaluated for their ability to augment the antifungal activity of clinically-approved anti-A. fumigatus agents including azoles, liposomal amphotericin B, and echinocandins. Transition milestones include the identification of lead compounds with defined inhibitory profiles and synergistic effects with existing drugs. In the R33 phase, we will conduct advanced in vitro efficacy and safety studies on the lead compounds, perform detailed pharmacological analyses, and assess the in vivo efficacy of lead compounds alone and in combination with approved antifungals using animal models of IA and FK A. fumigatus infections to validate their therapeutic potential. Successful completion of this project will yield novel AfPanK inhibitors that alone or when combined with approved antifungal drugs, can kill both sensitive and resistant A. fumigatus isolates. This therapeutic approach aims to reduce toxicity and improve treatment outcomes, potentially revolutionizing antifungal therapy.