Pan-active imidazolopiperazine antimalarials target thePlasmodium falciparumintracellular secretory pathway

Abstract

<jats:title>A<jats:sc>bstract</jats:sc></jats:title><jats:p>One of the most promising new compound classes in clinical development for the treatment of malaria is the imidazolopiperazines (IZPs) class. Human trials have demonstrated that members of the IZP series, which includes KAF156 (Ganaplacide) and GNF179, are potent and effective against <jats:italic>Plasmodium</jats:italic> symptomatic asexual blood-stage infections. Unlike other commonly used antimalarials, they also prevent transmission and block future infection in animal models. Despite the identification of several <jats:italic>Plasmodium falciparum</jats:italic> resistance mechanisms including mutations in ER-localized PfCARL (PfEMP65), Acetyl-coA transporter, and PfUGT transporter, IZP’s mechanism of action remains unknown.</jats:p><jats:p>To investigate, we combined <jats:italic>in vitro</jats:italic> evolution and whole-genome analysis in the model organism <jats:italic>Saccharomyces cerevisiae</jats:italic> with molecular, metabolomic, and chemogenomic methods, in <jats:italic>P. falciparum</jats:italic>. <jats:italic>S. cerevisiae</jats:italic> clones that resist IZP activity carry multiple mutations in genes that encode endoplasmic reticulum(ER)-based lipid homeostasis and autophagy including <jats:italic>elo2</jats:italic>, <jats:italic>elo3</jats:italic>, <jats:italic>sur2</jats:italic>, <jats:italic>atg15</jats:italic> and <jats:italic>lcb4</jats:italic>, as well as ER-based <jats:italic>sec66.</jats:italic> In <jats:italic>Plasmodium</jats:italic>, IZPs cause inhibition of protein trafficking, block the establishment of new permeation pathways and result in ER expansion. We also observe sensitization with other secretion inhibitors such as brefeldin A and golgicidin as well as synthetic lethality with PfSEC62. Our data show that IZPs target the secretory pathway and highlight a novel mechanism for blocking parasite growth and development that is distinct from those of standard compounds used to treat malaria. In addition, we provide physiological signatures and hallmarks for inhibitors that work through this mechanism of action and show that IZPs are tool compounds for studying ER-dependent protein processing in different species.</jats:p>

MalDA, Accelerating Malaria Drug Discovery

“…The latter is a novel imidazolopiperazine-based antimalarial that is pan-active against Plasmodium parasites [13,14]. This compound exerts its function by inhibiting protein trafficking and causes endoplasmic reticulum (ER) expansion in parasites, though its specific target is unknown [15]. It has good pharmacokinetic properties and is orally available [16].…”

“…Additionally, 4-and 8-animoquinolines, the arylamino alcohols, and artemisinins may also be considered targetless. A combination of approaches can be applied to identify targets for compounds for which using a single strategy proved insufficient [15].…”