Safety and Immunogenicity of Heterologous Prime-Boost Immunisation with Plasmodium falciparum Malaria Candidate Vaccines,ChAd63 ME-TRAP and MVA ME-TRAP,in Healthy Gambian and Kenyan Adults

Background

Heterologous prime boost immunization with chimpanzee adenovirus 63 (ChAd63) and Modified vaccinia Virus Ankara (MVA) vectored vaccines is a strategy recently shown to be capable of inducing strong cell mediated responses against several antigens from the malaria parasite. ChAd63-MVA expressing the Plasmodium falciparum pre-erythrocytic antigen ME-TRAP (multiple epitope string with thrombospondin-related adhesion protein) is a leading malaria vaccine candidate, capable of inducing sterile protection in malaria naïve adults following controlled human malaria infection (CHMI).

Methodology

We conducted two Phase Ib dose escalation clinical trials assessing the safety and immunogenicity of ChAd63-MVA ME-TRAP in 46 healthy malaria exposed adults in two African countries with similar malaria transmission patterns.

Results

ChAd63-MVA ME-TRAP was shown to be safe and immunogenic, inducing high-level T cell responses (median >1300 SFU/million PBMC).

Conclusions

ChAd63-MVA ME-TRAP is a safe and highly immunogenic vaccine regimen in adults with prior exposure to malaria. Further clinical trials to assess safety and immunogenicity in children and infants and protective efficacy in the field are now warranted.

Trial Registration

Pactr.org PACTR2010020001771828 http://www.pactr.org/ Pactr.org PACTR201008000221638 http://www.pactr.org/ ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01373879","term_id":"NCT01373879"}}NCT01373879 {"type":"clinical-trial","attrs":{"text":"NCT01373879","term_id":"NCT01373879"}}NCT01373879 ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01379430","term_id":"NCT01379430"}}NCT01379430 {"type":"clinical-trial","attrs":{"text":"NCT01379430","term_id":"NCT01379430"}}NCT01379430