The novel bis-1,2,4-triazine MIPS-0004373 demonstrates rapid and potent activity against all blood stages of the malaria parasite

Abstract

Novel bis-1,2,4-triazine compounds with potent in vitro activity against Plasmodium falciparum parasites were recently identified. The bis-1,2,4-triazines represent a unique antimalarial pharmacophore, and are proposed to act by a novel, but as-yet-unknown mechanism of action. This study investigated the activity of the bis-1,2,4-triazine, MIPS-0004373, across the mammalian lifecycle stages of the parasite, and profiled the kinetics of activity against blood and transmission-stage parasites in vitro and in vivo. MIPS-0004373 demonstrated rapid and potent activity against P. falciparum, with excellent in vitro activity against all asexual blood stages. Prolonged in vitro drug exposure failed to generate stable resistance de novo, suggesting a low propensity for the emergence of resistance. Excellent activity was observed against sexually-committed ring stage parasites, but activity against mature gametocytes was limited to inhibiting male gametogenesis. Assessment of liver stage activity demonstrated good activity in an in vitro P. berghei model, but no activity against P. cynomolgi hypnozoites or liver schizonts. The bis-1,2,4-triazine, MIPS-0004373, efficiently cleared an established P. berghei infection in vivo, with efficacy similar to artesunate and chloroquine, and a recrudescence profile comparable to chloroquine. This study demonstrates the suitability of bis-1,2,4-triazines for further development towards a novel treatment for acute malaria.