Identification and characterization of novel antifungals against Cryptococcus spp

About This Grant

Cryptococcus neoformans and Cryptococcus gattii are major fungal pathogens that cause severe infections, including cryptococcal meningitis, particularly in immunocompromised individuals. The World Health Organization (WHO) has identified C. neoformans as one of the top four highest critical priority fungal pathogens due to its substantial disease burden, increasing drug resistance, and the lack of effective therapies. Even with available treatments, the mortality rate for cryptococcal meningitis often exceeds 50%, highlighting the urgent need for new therapeutic strategies. Dihydroorotate dehydrogenase (DHODH), a pivotal enzyme in the de novo pyrimidine biosynthesis pathway, is a promising antifungal target due to its essential role in fungal survival. The success of olorofim, a selective DHODH inhibitor effective against Aspergillus fumigatus, underscores the therapeutic potential of targeting DHODH. However, olorofim is ineffective against C. neoformans and C. gattii, likely due to structural and sequence differences in their DHODHs. Importantly, studies have shown that pyrimidine biosynthesis in C. neoformans is vital for survival, as serum and cellular pyrimidine levels are insufficient to bypass DHODH inhibition. This makes CneDHODH an attractive and actionable target for antifungal drug development. This proposal focuses on developing selective inhibitors of CneDHODH to address the critical therapeutic gap for cryptococcal infections. High-throughput screening (HTS) will be carried out to identify inhibitors from large compound libraries. Identified hits will be validated for potency, selectivity against human DHODH, and antifungal activity against C. neoformans and other clinically relevant pathogens. Iterative medicinal chemistry will optimize lead compounds to improve their pharmacokinetics, potency, and selectivity. Structural studies, including co-crystallization and molecular modeling, will provide detailed insights into inhibitor binding, enabling rational drug design. Finally, optimized compounds will be tested in animal models of C. neoformans infection to evaluate their in vivo efficacy, pharmacokinetics, and safety. The development of CneDHODH inhibitors will address a critical unmet need for effective antifungal therapies for cryptococcal infections while extending the applicability of DHODH as a drug target to fungal pathogens beyond A. fumigatus. This work has the potential to transform the treatment of invasive fungal infections caused by Cryptococcus spp., significantly improving outcomes for vulnerable patients. By leveraging innovative screening approaches, structural insights, and medicinal chemistry, this project aims to deliver novel antifungal agents that could save lives and reduce the global burden of cryptococcal infections.