Mutations in the P-Type Cation-Transporter ATPase 4, PfATP4, Mediate Resistance to Both Aminopyrazole and Spiroindolone Antimalarials

Abstract

Aminopyrazoles are a new class of antimalarial compounds identified in a cellular antiparasitic screen with potent activity against Plasmodium falciparum asexual and sexual stage parasites. To investigate their unknown mechanism of action and thus identify their target, we cultured parasites in the presence of a representative member of the aminopyrazole series, GNF-Pf4492, to select for resistance. Whole genome sequencing of three resistant lines showed that each had acquired independent mutations in a P-type cation-transporter ATPase, PfATP4 (PF3D7_1211900), a protein implicated as the novel Plasmodium spp. target of another, structurally unrelated, class of antimalarials called the spiroindolones and characterized as an important sodium transporter of the cell. Similarly to the spiroindolones, GNF-Pf4492 blocks parasite transmission to mosquitoes and disrupts intracellular sodium homeostasis. Our data demonstrate that PfATP4 plays a critical role in cellular processes, can be inhibited by two distinct antimalarial pharmacophores, and supports the recent observations that PfATP4 is a critical antimalarial target.

New developments in anti-malarial target candidate and product profiles

“…Other PfATP4 inhibitors are in development, with SJ733 (+−SJ00557733; [86, 87]) recently starting phase I studies. A concern with targeting PfATP4 is that mutations in this gene confer resistance against aminopyrazoles, dihydroisoquinolones and spiroindolones [42, 88, 89]. The developmental pathway could be to demonstrate safety and tolerability of a parenteral formulation whilst assessing activity in adults with moderately severe malaria (hyperparasitemic cases; [85]).…”

Antimalarial drug resistance: linking Plasmodium falciparum parasite biology to the clinic

“…A complementary approach could be to pre-emptively block DSM265-resistance pathways by choosing as a partner another DHODH inhibitor against which DSM265-resistant parasites would be hypersensitive 109 . A similar phenomenon, whereby resistance to one class of inhibitors causes the mutated target to become hypersensitive to another inhibitor, has also been described for some PfATP4 mutants 110 .…”

Open Source Drug Discovery: Highly Potent Antimalarial Compounds Derived from the Tres Cantos Arylpyrroles

“…The relevant experiments measure the effect of a compound on the cytosolic [Na + ] ([Na + ] i ) in isolated (trophozoite-stage) parasites preloaded with the Na + -sensitive fluorescent indicator SBFI. PfATP4 is important since it is the proposed target of the antimalarial compound KAE609 116 that has recently successfully completed phase 2 trials, 117 as well as that of a pyrazoleamide 118 a dihydroisoquinolone ((+)-SJ-733), 119 various aminopyrazoles, 120 28 of the 400 potent antiplasmodial compounds comprising the MMV Malaria Box, 121 and a triazolopyrazine series being investigated by the Open Source Malaria Consortium. 122 All of these compounds cause an immediate increase in parasite [Na + ] i on addition to isolated parasites.…”