On-target, dual aminopeptidase inhibition provides cross-species antimalarial activity

Abstract

ABSTRACTTo combat the global burden of malaria, development of new drugs to replace or complement current therapies are urgently required. As drug resistance to existing treatments and clinical failures continue to rise, compounds targeting multiple life cycle stages and species need to be developed as a high priority. Here we show that the compoundMMV1557817is a nanomolar inhibitor of bothPlasmodium falciparumandPlasmodium vivaxaminopeptidases M1 and M17, leading to inhibition of end stage haemoglobin digestion in asexual parasites. Multi-stage analysis confirmed thatMMV1557817can also kill sexual stageP. falciparum, while cross-resistance studies confirmed the compound targets a mechanism of action distinct to current drug resistance mechanisms. Analysis of cross reactivity to homologous human enzymes shows the compound exhibits a high level of selectivity, whilst safety as well as druggability was confirmed in the murine modelP. berghei.MMV1557817-resistantP. falciparumparasites displayed only low-level resistance (<3-fold) and exhibited a slow growth rate that was quickly outcompeted by wild type parasites.MMV1557817-resistant parasites digest significantly more haemoglobin and possess a mutation inPfA-M17 that induces partial destabilisation of thePfA-M17 homohexamer, resulting in high-level resistance to specificPfA-M17 inhibition, but enhanced sensitivity to specificPfA-M1 inhibition, and importantly, these parasites were highly sensitive to artemisinin. Overall, these results confirmMMV1557817as a potential lead compound for further drug development and highlight the potential of dual inhibition of M1 and M17 as an effective multi-species drug targeting strategy.