Photo Credit: Christoph Burgstedt
The following is a summary of “Recombinant full-length Plasmodium falciparum circumsporozoite protein-based vaccine adjuvanted with GLA-LSQ: Results of Phase 1 testing with malaria challenge,” published in the February 2024 issue of Infectious Diseases by Friedman-Klabanoff et al.
Researchers conducted a retrospective study to develop more effective malaria vaccines with higher efficacy than RTS, S, the first marketed malaria vaccine aiming to eradicate the disease and its devastating impact.
They conducted an open-label Phase 1 study, escalating the dosage of a recombinant full-length circumsporozoite protein vaccine (rCSP) with adjuvant GLA-LSQ, administered to malaria-naïve adults on days 1, 29, and 85 or days 1 and 490. Primary objectives were to assess safety and reactogenicity, while secondary goals included evaluating antibody responses and monitoring Plasmodium falciparum parasitemia following controlled human malaria infection (CHMI).
The results showed that participants were divided into four groups, each receiving rCSP/GLA-LSQ: 10 µg x 3 (n = 20), 30 µg x 3 (n = 10), 60 µg x 3 (n = 10) or 60 µg x 2 (n = 9); ten participants received 30 µg rCSP alone x 3; and six served as infectivity controls. No serious AEs were reported. Rates of solicited and unsolicited adverse events were similar across all groups. Following CHMI, which was conducted 28 days after the final vaccinations, all 26 participants developed malaria. While increasing vaccine doses led to higher IgG titers, they did not reach the established benchmarks set by RTS, S.
Investigators concluded that while the rCSP/GLA-LSQ vaccine showed good safety, further optimization of adjuvants or dosing schedules is needed to achieve protective immunity against malaria.
