Combining the zebrafish embryo developmental toxicity assay (ZEDTA) with hemoglobin staining to accelerate the research of novel antimalarial drugs for pregnant women

Background: Malaria during pregnancy implies a high risk for the mother and the developing child. However, the

therapeutic options for pregnant women have historically been very limited, especially during the first trimester

of pregnancy due to potential adverse effects on embryo-fetal development. Recently, there has been great

controversy regarding these potential embryo-fetal adverse effects because the results of rodent studies were not

in accordance with the clinical data available, and finally the WHO has changed the recommendations for

pregnant women with uncomplicated P. falciparum malaria to treatment with artemether-lumefantrine during

the first trimester. The discrepancy between pre-clinical and clinical studies has been attributed to speciesdifferences

in the duration of the window of susceptibility of circulating primitive erythroblasts.

Methods: Here we provide a tool based on an alternative method to animal experimentation that accelerates the

research of novel drugs for pregnant women. We have adapted the zebrafish embryo developmental toxicity

assay to include hemoglobin staining in the embryos and two time-points of lethality and dysmorphogenesis

evaluation. These two time-points were selected to include one when the development is independent of and one

when the development is dependent of erythrocytes function. The method was used to test four marketed

antimalarial drugs and three new antimalarial drug candidates.

Results: Our combination of tests can correctly predict the teratogenic and non-teratogenic effects of several

antimalarial marketed drugs (artemisinin, quinine, chloroquine, and dihydroartemisinin + desbutyl-lumefantrine).

Furthermore, we have tested three new drug candidates (GS-GUAN, DONE3TCl, and YAT2150) with novel

mechanisms of action, and different from those of the marketed antimalarial drugs.

Conclusions: We propose a decision tree combining the results of the two time-points of evaluation together with

the information on significant erythrocyte depletion. The aim of this decision tree is to identify compounds with

no or lower hazard on teratogenicity or erythrocyte depletion at an early phase of the drug development process.