A Challenge Study to Assess the Blood-stage Efficacy of Full-length SUM-101 Malaria Vaccine Candidate

Full‐length MSP1/GLA‐SE (SUM‐101) malaria vaccine (formerly SumayaVac‐1) has beendeveloped by Sumaya Biotech, a spin‐off from Heidelberg University, Germany. SUM‐101 is avaccine based on the 3D7 strain (D‐form) of full‐length merozoite surface protein 1(full‐length MSP1). The full‐length MSP1 is expressed as a recombinant heterodimericprotein in E. coli and lyophilised at 150 μg/vial. The lyophilised MSP1 protein is storedat 2 ‐ 8°C. The adjuvant, GLA‐SE, was developed by Access to Advanced Health Institute(AAHI), a Washington non‐profit corporation with offices at 1616 Eastlake Ave. E, Suite400, Seattle, WA 98102, USA. It is a stable oil‐in‐water emulsion containing a syntheticanalogue of bacterial glucopyranosyl lipid A and functions as a toll‐like receptor 4agonist. A vial of the adjuvant contains 20μg of GLA‐SE in a 400μl emulsion. GLA‐SEadjuvant and emulsion formulations should be stored at 2 ‐ 8°C.The vaccine (SUM‐101) is prepared before administration by reconstituting the lyophilisedprotein in saline (aqueous 0.9% NaCl) and then combining it with the GLA‐SE adjuvant. Theformulated vaccine is stable at room temperature for up to 60 minutes and administeredintramuscularly.A Phase I first‐in‐human, double‐blinded, randomised trial (PMC6994672) was conducted toassess the safety and immunogenicity of SUM‐101 in healthy malaria‐naïve adult volunteersin Heidelberg, Germany. The trial demonstrated that SUM‐101 is safe, with no seriousadverse events (SAE) reported. Vaccination with SUM‐101 induced MSP1 specific IgG and IgMantibodies that activated Fc‐mediated effector mechanisms and were equally reactiveagainst the vaccine variant (MSP1D/3D7) and a heterologous variant of MSP1 (MSP1F/FCB1).In addition, a Phase Ib trial was conducted in Bagamoyo, Tanzania (NCT05644067, data notyet published) where 20 healthy Tanzanian adults were vaccinated with SUM‐101.Preliminary results indicate that SUM‐101 is safe and well‐tolerated in healthy Africanadults living in malaria‐endemic areas, with ongoing assessments of antibody responses.Concurrently with this trial, a Phase Ib, randomised, controlled age de‐escalation,dose‐finding study to evaluate the safety, reactogenicity and immunogenicity offull‐length MSP1/GLA‐SE (SUM‐101) malaria vaccine in healthy young children, and infants(NCT06618885) will be conducted in Burkina Faso. The protocol has been submitted forethical and regulatory approval in Burkina Faso.