Venkatraman, N., et al. R21 in Matrix-M adjuvant in UK malaria-naive adult men and non-pregnant women aged 18-45 years: an open-label, partially blinded, phase 1-2a controlled human malaria infection study.
Lancet Microbe, 2025 Mar, 6(3):100867. PMID: 39805301
The study evaluates the efficacy and safety of the R21 malaria vaccine candidate (Jenner Institute, University of Oxford) formulated with the Matrix-M adjuvant (Novavax) in a phase 1–2a malaria sporozoite challenge study among healthy, malaria-naïve volunteers.
The results demonstrate that R21/MM induces humoral immunogenicity similar to the RTS,S/AS01 vaccine at lower antigen doses, accompanied by significantly reduced reactogenicity. The three-dose regimen of R21/MM elicited robust IgG antibody responses against the circumsporozoite protein (CSP) NANP repeat region, with significant antibody responses measured by ELISA. However, a fractional third dose did not enhance antibody levels or protection compared to the standard regimen. T-cell responses to CSP were generally weak and transient, although increased interferon-gamma (IFN-γ) production was observed in response to CSP peptides.
The study supports further development of R21/MM for field efficacy trials in young children in malaria-endemic regions, particularly in sub-Saharan Africa.
Comments from Desert King International: Notably, R21/MM is now prequalified and recommended by WHO for pediatric use as a cost-effective malaria prevention strategy.
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