A Phase Ia Clinical Trial to Assess the Safety and Immunogenicity of New Plasmodium Vivax Malaria Vaccine Candidates ChAd63 PvDBP Alone and With MVA PvDBP
This Phase Ia clinical trial is designed to assess the safety and immunogenicity of the chimpanzee adenovirus 63 (ChAd63) P. vivax Duffy Binding Protein (PvDBP) vaccine with or without Modified Vaccinia Ankara (MVA) PvDBP in healthy volunteers.
An important element of Plasmodium vivax infection is the protein that it uses to invade red blood cells, known as Duffy-binding protein (PvDBP). Whilst Plasmodium falciparum utilizes a range of erythrocyte-binding ligands and therefore has multiple red blood cell invasion pathways available to it, it is believed that P. vivax primarily uses a pathway whereby region II of PvDBP (PvDBP_RII) binds to CD71+ reticulocytes via the human Duffy antigen receptor for chemokines (DARC). This Phase Ia clinical trial to assess the safety and efficacy of two vaccines that target this invasion pathway, with the aim of inducing the formation of antibodies against PvDBP and inhibiting red blood cell invasion by the parasite.
To test the vaccines, 24 healthy, malaria-naïve volunteers were divided into four groups. Group 1 received an initial dose of ChAd63 PvDBP. With the safety of this dose established, group 2 received a higher dose. Groups 3 and 4 also received the higher dose ChAd63 PvDBP, with group 3 then receiving a low dose prime-boost of MVA PvDBP at day 56 and group 4 receiving a higher dose of MVA PvDBP at day 56, again having established the safety of the lower dose previously.
Primary outcome: The safety in healthy volunteers of two new candidate malaria vaccines, ChAd63 PvDBP administered alone, and with MVA PvDBP, in a prime-boost regime.
Secondary outcome:The humoral and cellular immunogenicity of ChAd63 PvDBP, when administered to healthy volunteers alone and with MVA PvDBP.
ClinicalTrials.gov Identifier: NCT01816113
Study Phase: Ia
Study Type : Interventional
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Prevention