ACT-451840 is a new compound with potent activity against sensitive and resistant Plasmodium falciparum strains. ACT-451840 has been used in trials studying malaria. ACT-451840 appears to have a distinct mode of action that sets it apart from current antimalarial drugs, including artemisinins. It has a rapid onset of action as well as activity on all blood-borne (erythrocytic) stages, which is retained against multiple resistant parasites, including artemisinin-resistant strains. Unlike the majority of antimalarial agents, ACT-451840 has the potential to block disease transmission due to its activity on gametocytes. he antimalarial activity of ACT-451840 was studied in an experimental induced blood stage malaria clinical trial performed in collaboration with MMV Medicines for Malaria Ventures at the laboratories of Professor James McCarthy, MBBS, MD of the Royal Brisbane and Women's Hospital in Herston, Australia. In the trial, ACT-451840 was safe and well tolerated and showed clinical efficacy against the early stages of P. falciparum infections. The PK/PD model developed from this proof-of-concept study with eight healthy subjects enabled prediction of therapeutic effects, with cure rates following 1 week of therapy (single daily doses) predicted to be equivalent to artesunate monotherapy.