This Phase 1 study, conducted in malaria-naïve adults in Shanghai, China, was designed to determine the safety, reactogenicity, and immunogenicity of the chimeric recombinant Plasmodium falciparum vaccine candidate PfCP2.9 formulated with the blood-stage apical membrane antigen-1 (AMA1), merozoite surface protein-1 (MSP1), and water-in-oil adjuvant ISA 720.
Volunteers were randomized into three dose-escalating groups (5 µg, 20 µg, and 50 µg), and received multiple intramuscular vaccinations adjuvanted in ISA 720, with subjects in the control group receiving ISA 720 alone.
The study was designed with two objectives:
- Assess the safety and reactogenicity of PfCP2.9AMA1 in malaria-naïve adults by monitoring for occurrence of solicited signs and symptoms, occurrence of unsolicited symptoms, and the occurrence of serious adverse events during the study period.
- Quantify the humoral immune response via antibody titer, and assess the ability of antibodies to inhibit the growth of parasites.
Outcomes/Next steps: Findings were published in Vaccine in 2008.
PfCP2.9AMA1 was found to be safe and well-tolerated, with low systemic reactogenicity in subjects. Despite its immunogenicity, little growth inhibitory activity was observed in sera for either strain of Plasmodium falciparum.
Malkin E, Hu J, Li Z, Chen Z, Bi X, et al. A Phase 1 trial of PfCP2.9: an AMA1/MSP1 chimeric recombinant protein vaccine for Plasmodium falciparum malaria. Vaccine. 2008;26(52):6864-6873.