This Phase 1/2a sporozoite challenge trial, conducted in malaria-naïve adults living in Oxford, Southampton, and London, United Kingdom, aimed to determine whether combining partially effective vaccine approaches, primarily targeting induction of pre-erythrocytic cell-mediated immune responses to multiple epitope string and thrombospondin-related adhesion protein (ME-TRAP), circumsporozoite protein (CS), and apical membrane antigen 1 (AMA-1) increased the levels of protective efficacy in controlled human malaria infection studies.
The study was designed with two objectives:
- Assess the safety and efficacy of two prime-boost vaccine approaches in malaria-naïve adults: ChAd63-MVA ME-TRAP/ChAd63-MVA CS, and ChAd63-MVA ME-TRAP/ChAd63-MVA CS/ChAd63-MVA AMA1.
- Assess the immunogenicity of the candidate vaccines against sporozoite challenge with Plasmodium falciparum.
A variety of local and systemic reactions were noted in both groups of subjects, particularly after receiving the MVA boost dose. However, these were found to be in line with reactogenicity experienced in previous studies. No immunological assessments conducted showed a clear correlation with protection against challenge.
Based on the outcomes of this study, the PATH Malaria Vaccine Initiative did not make further investments.
This project was supported by the PATH Malaria Vaccine Initiative through the United States Agency for International Development, Bureau for Global Health, Infectious Disease Division, under the terms of Cooperative Agreement GHS-A-00-04-00016-00.