Potent acridone antimalarial against all three life stages of Plasmodium

Antimalarial therapeutics ideally should target all three major Plasmodium life cycle stages. Here we present an acridone antimalarial chemotype that is potent against blood, liver, and mosquito stages of malaria parasites. Attributes of lead candidate T111 include potent in vitro activity against cultured parasites, ex vivo activity against clinical isolates, oral single-dose cure in an asexual blood-stage rodent model, inhibition of sexual blood-stage parasites, activity against relapsing parasites in non-human primate liver cells, prevention of parasite development in mosquitoes, and synergy in combination with tafenoquine against blood- and liver-stage parasites. Analysis of parasites selected for resistance to T111 suggests inhibition of the mitochondrial electron transport chain, with a mechanism distinct from that of other antimalarials in use or under development. The safety profile of T111, including toxicology evaluations in rats, absence of hemolytic toxicity, and low genotoxicity and cardiotoxicity potential, demonstrates a favorable therapeutic index. Overall, T111 emerges as a promising candidate for treatment and prevention of malaria, with potential for single-dose cure of bloodstream infections, radical cure of liver infections, and interruption of transmission to mosquitoes.