SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate

Abstract In the aim of designing and developing a novel saponin-based adjuvant system, we combined the QS21 saponin with low microgram amounts of the fully synthetic TLR4 agonist, E6020, in cholesterol-containing liposomes. The resulting adjuvant system, termed SPA14, appeared as a long-term stable...

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Main Authors: Ernesto Luna, Sophie Ruiz, Marie Garinot, Cyril Chavagnac, Pankaj Agrawal, John Escobar, Laurent Revet, Marie-Jeanne Asensio, Fabienne Piras, Francis G. Fang, Donald R. Drake, Bachra Rokbi, Daniel Larocque, Jean Haensler
Format: Article
Language:English
Published: Nature Portfolio 2024-12-01
Series:npj Vaccines
Online Access:https://doi.org/10.1038/s41541-024-01046-0
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author Ernesto Luna
Sophie Ruiz
Marie Garinot
Cyril Chavagnac
Pankaj Agrawal
John Escobar
Laurent Revet
Marie-Jeanne Asensio
Fabienne Piras
Francis G. Fang
Donald R. Drake
Bachra Rokbi
Daniel Larocque
Jean Haensler
author_facet Ernesto Luna
Sophie Ruiz
Marie Garinot
Cyril Chavagnac
Pankaj Agrawal
John Escobar
Laurent Revet
Marie-Jeanne Asensio
Fabienne Piras
Francis G. Fang
Donald R. Drake
Bachra Rokbi
Daniel Larocque
Jean Haensler
author_sort Ernesto Luna
collection DOAJ
description Abstract In the aim of designing and developing a novel saponin-based adjuvant system, we combined the QS21 saponin with low microgram amounts of the fully synthetic TLR4 agonist, E6020, in cholesterol-containing liposomes. The resulting adjuvant system, termed SPA14, appeared as a long-term stable and homogeneous suspension of mostly unilamellar and a few multilamellar vesicles, with an average hydrodynamic diameter of 93 nm, when formulated in citrate buffer at pH 6.0-6.5. When compared in an in vitro human innate immunity construct to AS01B, the QS21/MPL® liposomal adjuvant system of GSK, and with QS21-Liposomes used as benchmarks, SPA14 displayed the strongest immunostimulatory potential based on antigen-presenting cell (APC) activation and cytokine secretion, which was essentially driven by the highly active E6020 agonist in this assay. When tested as an adjuvant in vivo with human cytomegalovirus glycoprotein B (gB) and pentamer complex (PC) as test antigens, SPA14 was generally well tolerated and as active as AS01B for the induction of long-lasting CMV-neutralizing antibodies in mice and non-human primates (NHPs). Both adjuvants promoted the induction of Th-1 responses based on IgG2c production in mice and IFN-γ production in mice and NHPs, but in mice, a higher level of Th-2 cytokines (IL-5) and higher IgG1 over IgG2c secreting cells ratios were obtained with SPA14 indicating that the adjuvant profile of SPA14 could be less Th-1 biased than that of AS01B. From a developability standpoint, SPA14 could be manufactured by a simple and scalable ethanol injection method, owing to the high solubility in ethanol of all its lipidic components, including E6020. Furthermore, E6020 is a single molecule, well-characterized fully synthetic TLR4 agonist constructed in eight synthetic steps from entirely crystalline starting materials and intermediates via an optimized high-yield synthetic route. Overall, our data suggest that SPA14 is a viable, easy-to-manufacture, potent novel adjuvant system that could be broadly applicable as a ready-to-mix adjuvant in the form of a long-term stable liquid formulation.
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spelling doaj-art-f69c1b5a209a490bb730978a1721d9772025-02-09T12:11:03ZengNature Portfolionpj Vaccines2059-01052024-12-019111510.1038/s41541-024-01046-0SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidateErnesto Luna0Sophie Ruiz1Marie Garinot2Cyril Chavagnac3Pankaj Agrawal4John Escobar5Laurent Revet6Marie-Jeanne Asensio7Fabienne Piras8Francis G. Fang9Donald R. Drake10Bachra Rokbi11Daniel Larocque12Jean Haensler13Sanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DEisai IncSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DSanofi Vaccines business unit, R&DAbstract In the aim of designing and developing a novel saponin-based adjuvant system, we combined the QS21 saponin with low microgram amounts of the fully synthetic TLR4 agonist, E6020, in cholesterol-containing liposomes. The resulting adjuvant system, termed SPA14, appeared as a long-term stable and homogeneous suspension of mostly unilamellar and a few multilamellar vesicles, with an average hydrodynamic diameter of 93 nm, when formulated in citrate buffer at pH 6.0-6.5. When compared in an in vitro human innate immunity construct to AS01B, the QS21/MPL® liposomal adjuvant system of GSK, and with QS21-Liposomes used as benchmarks, SPA14 displayed the strongest immunostimulatory potential based on antigen-presenting cell (APC) activation and cytokine secretion, which was essentially driven by the highly active E6020 agonist in this assay. When tested as an adjuvant in vivo with human cytomegalovirus glycoprotein B (gB) and pentamer complex (PC) as test antigens, SPA14 was generally well tolerated and as active as AS01B for the induction of long-lasting CMV-neutralizing antibodies in mice and non-human primates (NHPs). Both adjuvants promoted the induction of Th-1 responses based on IgG2c production in mice and IFN-γ production in mice and NHPs, but in mice, a higher level of Th-2 cytokines (IL-5) and higher IgG1 over IgG2c secreting cells ratios were obtained with SPA14 indicating that the adjuvant profile of SPA14 could be less Th-1 biased than that of AS01B. From a developability standpoint, SPA14 could be manufactured by a simple and scalable ethanol injection method, owing to the high solubility in ethanol of all its lipidic components, including E6020. Furthermore, E6020 is a single molecule, well-characterized fully synthetic TLR4 agonist constructed in eight synthetic steps from entirely crystalline starting materials and intermediates via an optimized high-yield synthetic route. Overall, our data suggest that SPA14 is a viable, easy-to-manufacture, potent novel adjuvant system that could be broadly applicable as a ready-to-mix adjuvant in the form of a long-term stable liquid formulation.https://doi.org/10.1038/s41541-024-01046-0
spellingShingle Ernesto Luna
Sophie Ruiz
Marie Garinot
Cyril Chavagnac
Pankaj Agrawal
John Escobar
Laurent Revet
Marie-Jeanne Asensio
Fabienne Piras
Francis G. Fang
Donald R. Drake
Bachra Rokbi
Daniel Larocque
Jean Haensler
SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate
npj Vaccines
title SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate
title_full SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate
title_fullStr SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate
title_full_unstemmed SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate
title_short SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate
title_sort spa14 liposomes combining saponin with fully synthetic tlr4 agonist provide adjuvanticity to hcmv vaccine candidate
url https://doi.org/10.1038/s41541-024-01046-0
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