Conference Agenda

Combating malaria caused by Plasmodium falciparum requires strategies to mitigate drug resistance. The clinical candidates cipargamin and SJ733 target the Na⁺ pump PfATP4. A G358S mutation in PfATP4, identified in 68% of recrudescent cases in a cipargamin clinical trial, confers high-level resistance to both compounds while simultaneously increasing parasite sensitivity to PfATP4 inhibitors belonging to two distinct chemical classes (‘I’ and ‘II’). To investigate whether collateral sensitivity could be leveraged in preserving cipargamin efficacy, we exposed ‘hypermutator’ parasites to class I and II compounds in combination with a high (20× IC₅₀) concentration of cipargamin. The cipargamin/class I combination led to an L354V mutation in PfATP4, while for cipargamin/class II, no viable parasites emerged across 6 selections. However, exposure of PfATP4^G358S parasites to a class II compound drove the acquisition of an additional PfATP4 mutation (N355Y). The N355Y+G358S mutants exhibited > 2000-fold and 650-fold resistance to cipargamin and SJ733, respectively. The PfATP4-G358A mutation was also associated with treatment failure in the clinical trial. We show that this mutation confers 500-fold resistance to cipargamin, confirming its clinical significance. Together, these findings highlight that while multiple PfATP4 mutations can compromise cipargamin efficacy, combining certain PfATP4 inhibitors increases the barrier for resistance.