Background: Plasmodium falciparum Apical Membrane Antigen 1 Diversity Covering (PfAMA1-DiCo) candidate vaccine is a formulation of three recombinant variants of AMA1 designed to provide broader protection against parasites with varying AMA1 sequences.
Methods: In this staggered phase Ia/Ib randomized, double blind trial, healthy French adults received AMA1-DiCo with either Alhydrogel® (n=15) or GLA-SE (n=15). Following a safety assessment in French volunteers, GLA-SE was chosen for the phase Ib trial where healthy Burkinabe adults received either AMA1-DiCo/GLA-SE (n=18) or placebo (n=18). AMA1-DiCo (50µg) was administered intramuscularly at baseline, Week 4 and 26.
Results: AMAI-DiCo was safe, well tolerated either with Alhydrogel® or GLA-SE. In European volunteers, the ratios of IgG increase from baseline were about 100 fold in Alhydrogel® group and 200-300 fold in GLA-SE group for the three antigens. In African volunteers, immunization resulted in IgG levels exceeding those observed for the European volunteers with a 4-fold increase. DiCo-specific IgG remained higher 26weeks after the third immunization than at baseline in both European and African volunteers. Induced antibodies were reactive against whole parasite derived from different strains.
Conclusion: AMA1-DiCo vaccine was safe and immunogenic whatever the adjuvant although GLA-SE appeared more potent than Alhydrogel® at inducing IgG responses.
Clinical trials registration: ClinicalTrials.gov NCT02014727; PACTR201402000719423.
Keywords: Adjuvants; Apical membrane antigen 1; Immunogenicity; Malaria; Plasmodium falciparum; Safety; Vaccine trial.
Copyright © 2017. Published by Elsevier Ltd.