Science

Targeting GPI with SSCVs

A conserved oligosaccharide, chemically synthesised, conjugated to a clinically and commercially validated carrier protein. The target is conserved across complex life-cycle stages, species, and even pathogens from different biological kingdoms — which is why the GPI SSCV platform extends beyond malaria to a pipeline of products with blockbuster potential.

Protein targets vary, GPI — not so much

The efficacy of protein-targeting vaccines is limited by variation — the protein target on the pathogen changes or disappears altogether. Instead of a protein, our GPI target is an oligosaccharide that is less easily varied and more highly conserved across parasites, mycobacteria and fungal pathogens. They have evolved over millennia to exploit GPI as the lynchpin of their strategy to evade our immune systems, but in doing so have exposed their own Achilles’ heel. We target GPI to defeat them.

Competing vaccines target different proteins (A, B, C …) that change. ST101 targets the same GPI tether, that does not change, across infection, replication and disease, and transmission.

Pan-stage by design

Preclinical studies of ST101 show high-titre anti-GPI antibodies, prevention of sporozoite infection, limited blood-stage replication, neutralisation of the dominant GPI toxin, and blockade of sexual-stage transmission — with potent synergy against GPI-anchored protein vaccines, including homologues of RTS,S and R21. Compounding efficacy in all species — across all stages.

Infection

Sporozoite invasion of the liver.

Replication

Parasite expansion inside hepatocytes.

Disease

Blood-stage replication and GPI toxin.

Transmission

Sexual stages taken up by the mosquito.

Chemical synthesis

The saccharide is made by chemical synthesis, not bulk fermentation. Molecular definition, batch consistency, and a path to industrial scale without the need to grow huge cultures of pathogens.

Validated glycoconjugate platform

The GPI glycan is linked to a clinically and commercially proven carrier-protein platform — the same as used for a $25B category of licensed bacterial glycoconjugate vaccines.

Validated correlate of protection

Our published clinical cohort data shows that natural immunity against our GPI target strongly correlates with less infection and less disease.

Fit for rollout

Stability under standard refrigeration, dosing compatible with WHO Expanded Programme on Immunization schedules, and a cost of goods designed for endemic-market access.

Across kingdoms

The same idea, beyond malaria

Mycobacterial phosphatidyl-myo-inositol mannosides share structural kinship with GPI. ST208, a synthetic PIM mannose conjugate, potentiated BCG more than ten-fold in murine tuberculosis — the first saccharide-conjugate vaccine with published in-vivo TB efficacy. Invasive fungi present a further kingdom leap now in discovery as ST300.

See the pipeline

GPI anchor schematic on a parasite membrane.

References

Louis Schofield — publication record — indexed publications (EBSCO).

Miranda-Hernandez S, Sathkumara HD, Zhao G, Schofield L, Kupz A. Co-administration of a synthetic saccharide conjugate vaccine with BCG provides synergistic protection against murine tuberculosis. Vaccine. 2025. DOI
Michon P, Cole-Tobian JL, Dabod E, Schoepflin S, Igu J, Susapu M, Tarongka N, Zimmerman PA, Reeder JC, Beeson JG, Schofield L, King CL, Mueller I. The risk of malarial infections and disease in Papua New Guinean children. Am J Trop Med Hyg. 2007;76(6):997–1008. DOI
Schofield L, Hewitt MC, Evans K, Siomos MA, Seeberger PH. Synthetic GPI as a candidate anti-toxic vaccine in a model of malaria. Nature. 2002;418:785–789. DOI