This Phase 1 study, conducted in malaria-naïve adults in the United States, evaluated the safety, reactogenicity, and immunogenicity of two blood-stage malaria vaccine candidates, merozoite surface protein-1 (MSP142)-FVO P. falciparum strain and MSP142-3D7 strain, both formulated with the aluminum hydroxide adjuvant Alhydrogel®, manufactured by Brenntag Biosector A/S.
Volunteers were divided into three dose-escalating groups (5 µg, 20 µg, and 80 µg), and alternated to receive multiple intramuscular vaccinations of either MSP142-FVO/Alhydrogel or MSP142-3D7/Alhydrogel.
The study was designed with two objectives:
- Assess the safety and reactogenicity of MSP142-FVO/Alhydrogel and MSP142-3D7/Alhydrogel 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 PLoS Clinical Trials in 2007.
Both MSP142-FVO/Alhydrogel and MSP142-3D7/Alhydrogel were found to be safe and well-tolerated, with low systemic reactogenicity in subjects. Despite immunogenicity levels generated by these formulations, little growth inhibitory activity was observed in sera for either FVO or 3D7 strains of Plasmodium falciparum.
Malkin E, Long CA, Stowers AW, Zou L, Singh S, et al. Phase 1 study of two merozoite surface protein 1 (MSP142) vaccines for Plasmodium falciparum malaria. PLoS Clinical Trials. 2007;2(4):e12.