Safety and Immunogenicity of Pfs25-EPA/Alhydrogel®, a Transmission Blocking Vaccine against Plasmodium falciparum: An Open Label Study in Malaria Naïve Adults

Kawsar R. Talaat, Ruth D. Ellis, Janet Hurd, Autumn Hentrich, Erin Gabriel, Noreen A. Hynes, Kelly M. Rausch, Daming Zhu, Olga Muratova, Raul Herrera, Charles Anderson, David Jones (+11 others)
2016 PLoS ONE  
Transmission-blocking vaccines (TBVs) that target sexual stage parasite development could be an integral part of measures for malaria elimination. Pfs25 is a leading TBV candidate, and previous studies conducted in animals demonstrated an improvement of its functional immunogenicity after conjugation to EPA, a recombinant, detoxified ExoProtein A from Pseudomonas aeruginosa. In this report, we describe results of an open-label, doseescalating Phase 1 trial to assess the safety and
more » ... of Pfs25-EPA conjugates formulated with Alhydrogel 1 . Thirty malaria-naïve healthy adults received up to four doses of the conjugate vaccine, with 8, 16, or 47 μg of conjugated Pfs25 mass, at 0, 2, 4, and 10 months. Vaccinations were generally well tolerated. The majority of solicited adverse events were mild in severity with pain at the injection site the most common complaint. Anemia was the most common laboratory abnormality, but was considered possibly related to the study in only a minority of cases. No vaccine-related serious adverse events occurred. The peak geometric mean anti-Pfs25 antibody level in the highest dose group was 88 (95% CI 53, 147) μg/mL two weeks after the 4 th vaccination, and declined to near baseline one year later. Antibody avidity increased over successive vaccinations. Transmission blocking activity demonstrated in a standard membrane feeding assay (SMFA) also increased from the second to the third dose, and correlated with antibody titer and, after the final dose, with PLOS ONE |
doi:10.1371/journal.pone.0163144 pmid:27749907 pmcid:PMC5066979 fatcat:a244rn3stzhjnlxuh5wlkayqgu