Drug Interaction Studies of Cabamiquine:Ganaplacide Combination against Hepatic Plasmodium berghei

Abstract

New antimalarial combination therapies with novel modes of action are required to counter the emergence and spread of Plasmodium drug resistance against existing therapeutics. Here, we present a study to evaluate the preventive activity of a combination of clinical antimalarial drug candidates, cabamiquine and ganaplacide, that have multistage activity against the liver and blood stages of Plasmodium infection. Cabamiquine (DDD107498, M5717) inhibits parasite protein synthesis, and ganaplacide (KAF156) inhibits protein trafficking, blocks the establishment of new permeation pathways, and causes endoplasmic reticulum expansion. The pharmacodynamic parameters of a combination of the two compounds were assessed employing a pharmacometrics approach in conjunction with in vitro-in silico checkerboard analysis. The in vitro study was performed on a previously established 3D infection platform based on human hepatic cell lines that sustain infection by rodent P. berghei parasites. The in vivo efficacy of this drug combination was assessed against the liver stage of the P. berghei. Our results show that the combination of both drugs at the tested concentrations does not interfere with the drugs respective mode of action or affect hepatocyte cell viability. The drug combination was fully effective in preventing the appearance of blood stage parasites when a systemic plasma C_av0-24/EC₅₀ ratio >2 for ganaplacide and >5 for cabamiquine was achieved. These findings demonstrate that chemoprevention using a combination of cabamiquine and ganaplacide has the potential to target the asymptomatic liver stage of Plasmodium infection and prevent the development of parasitemia.

Keywords: Antimalarial; Cabamiquine; Combination therapy; Ganaplacide; Liver stage infection; Preclinical.

Figure 1

Individual model fits for cabamiquine:ganaplacide combination for thein vitro dug-drug-PD interaction assay data using P. berghei parasites. Model predictions from the final model (lines) and original data (points) for each study (colors); each facet displays a studied scenario for cabamiquine (A1) and ganaplacide (A2). The numbers in each facet present the concentration of either cabamiquine or ganaplacide in nM in each well.

Figure 2

Heat map of the additive interaction (Bliss Independence) of cabamiquine and ganaplacide. (A) Read–out–heat map and (B) Zoomed read–out–heat map. Color gradient visualizes the assay read out at 24 h, the gray lines represent the isoboles of identical effects.

Figure 3

Evaluation of ganaplacide and cabamiquine drug combination in the P. berghei mouse model. (A) Schematic representation of the infection strategy and mode of exposure to the drug combination. (B) Representative ventral view images of NMRI mice at 48 h after administration of P. berghei sporozoites and after 24 h exposure to cabamiquine and ganaplacide as monotherapies and in combination (as indicated). Heat maps of mice represent intensity of bioluminescence, radiance as indicated by pseudocolor scale.