Dual plasmepsin IX and X inhibitors are refractory to development of resistance

Favuzza, P; Dans, MG; Su, W; Thompson, JK; Hodder, AN; Ngo, A; Penington, JS; Marapana, DS; Dziekan, JM; Papenfuss, AT; de Lera Ruiz, M; Coyle, R; Lee, MCS; McCauley, JA; Lowes, K; Olsen, DB; Sleebs, BE; Cowman, AF

Author(s): Favuzza, P; Dans, MG; Su, W; Thompson, JK; Hodder, AN; Ngo, A; Penington, JS; Marapana, DS; Dziekan, JM; Papenfuss, AT; de Lera Ruiz, M; Coyle, R; Lee, MCS; McCauley, JA; Lowes, K; Olsen, DB; Sleebs, BE; Cowman, AF;
Details: Publication Year 2026-09,Volume 22,Issue #9,Page e1014068
Journal Title: PLOS Pathogens
Abstract: Artemisinin-based combination therapies (ACTs) remain the cornerstone of malaria treatment, but emerging resistance threatens their efficacy. The potential for the development of drug resistance against plasmepsin X (PMX)-selective inhibitors and dual plasmepsin IX/X (PMIX/X) inhibitors was investigated in Plasmodium falciparum. A series of PMX-selective (WM4, WM76, WM92) and PMIX/X dual inhibitors (WM382, WM09, WM42) were characterised for potency against parasite growth and enzyme inhibition. In vitro selection experiments showed that all compounds had a high barrier to resistance, although parasites with reduced sensitivity to PMX‑selective inhibitors could still be selected. Resistance mechanisms involved pmx gene amplification and point mutations (D245N, S315P, S359P, I363L) that alter inhibitor binding. Recombinant expression and Michaelis-Menten kinetics demonstrated that these mutations impair drug binding whilst preserving PMX catalytic function. Reverse genetics confirmed that introducing these mutations into the pmx gene resulted in decreased potency of the inhibitors. In this study, resistance to the PMIX/X dual inhibitors evaluated here could not be selected, despite prolonged selection pressure. Antimalarial Resistome Barcoding (AReBar) assays confirmed the absence of pre-existing resistance to either inhibitor class. Critically, PMIX/X dual inhibitors maintained efficacy against parasites with decreased sensitivity to PMX-selective compounds. These findings demonstrate that dual PMIX/X inhibitors present a substantially higher barrier to resistance than PMX-selective inhibitors, informing antimalarial drug development strategies and highlighting dual-target inhibition as a promising approach to mitigate resistance risks.
Publisher: PLOS
Keywords: *Aspartic Acid Endopeptidases/antagonists & inhibitors/genetics/metabolism; *Plasmodium falciparum/drug effects/genetics/enzymology; *Drug Resistance/drug effects/genetics; *Antimalarials/pharmacology; Humans; *Protozoan Proteins/antagonists & inhibitors/genetics/metabolism; *Malaria, Falciparum/drug therapy/parasitology
Research Division(s): Infection and Global Health; New Medicines and Diagnostics; Bioinformatics and Computational Biology
PubMed ID: 42709875
Publisher's Version: https://doi.org/10.1371/journal.ppat.1014068
Open Access at Publisher's Site: https://doi.org/10.1371/journal.ppat.1014068
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 2026-09-14 08:56:32

Last Modified: 2026-09-14 08:56:54