Non-toxic adjuvant formulation comprising a monophosphoryl lipid A (MPLA)-containing liposome composition and a saponin
Inventors
Alving, Carl R. • BECK, Zoltan
Assignees
United States Department of the Army
Publication Number
US-10434167-B2
Publication Date
2019-10-08
Expiration Date
2035-03-25
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Abstract
Provided herein is an adjuvant formulation comprising a monophosphoryl lipid A (MPLA)-containing liposome composition to saponin (e.g., QS-21), wherein the liposome composition comprises i) a lipid bilayer comprising phospholipids in which the hydrocarbon chains have a melting temperature in water of ≥23° C. and ii) cholesterol at a mole percent concentration of greater than about 50% (mol/mol), preferably about 55% to about 71% (mol/mol), or more preferably about 55% (mol/mol). The adjuvant formulation displays minimal toxicity of either lipid A or saponin.
Core Innovation
The invention provides an adjuvant formulation comprising a monophosphoryl lipid A (MPLA)-containing liposome composition combined with at least one saponin, preferably QS-21, wherein the liposome composition includes a lipid bilayer of phospholipids with hydrocarbon chains having a melting temperature in water of ≥23° C. and cholesterol at a mole percent concentration greater than about 50% (mol/mol), preferably about 55% to about 71% (mol/mol). The formulation demonstrates minimal toxicity from either lipid A or saponin.
The problem addressed is that while lipopolysaccharides (LPS) and lipid A exhibit strong adjuvanticity, their high toxicity limits their vaccine use. Similarly, saponins like QS-21, though potent adjuvants, cause cytotoxicity notably hemolysis of red blood cells. There exists a need for vaccine delivery compositions and adjuvants that enhance the immune response without these associated toxicities.
This invention contrasts prior adjuvant formulations by providing liposome compositions with a specific phospholipid melting temperature and high cholesterol content that complex with MPLA and saponins to reduce toxicity. The combination modulates membrane biochemistry and results in reduced hemolytic activity and improved safety while maintaining or enhancing immunogenic potency.
Claims Coverage
The patent contains one independent claim defining an adjuvant formulation comprising specific unilamellar liposomes with defined components and characteristics. The main inventive features include the liposome bilayer composition, cholesterol concentration, MPLA presence, saponin type, and their ratios.
Specific liposome bilayer composition with defined phospholipids
The adjuvant formulation comprises unilamellar liposomes having a bilayer consisting of at least one phosphatidylcholine (PC) and/or phosphatidylglycerol (PG) selected from dimyristoyl phosphatidylcholine (DMPC), dipalmitoyl phosphatidylcholine (DPPC), distearyl phosphatidylcholine (DSPC), dimyristoyl phosphatidylglycerol (DMPG), dipalmitoyl phosphatidylglycerol (DPPG), and distearyl phosphatidylglycerol (DSPG).
Cholesterol concentration in liposome bilayer
The mole ratio of cholesterol to phospholipids in the liposome bilayer is about 55:45 to about 71:29, preferably about 55:45, conferring stability and impacting adjuvant properties.
Incorporation of monophosphoryl lipid A (MPLA)
MPLA is incorporated into the liposome bilayer at a mole ratio to phospholipids ranging from about 1:5.6 to about 1:880, with a preferred range of about 1:88 to about 1:220, providing potent immunostimulatory activity.
Inclusion of saponin as adjuvant component
The formulation includes a saponin selected from QS-7, QS-18, QS-21, or mixtures thereof, with QS-21 preferred, at concentrations of about 1 mg/ml or less in the liposome suspension to reduce toxicity while enhancing immune response.
The independent claim covers an adjuvant formulation comprising unilamellar liposomes composed of specified phospholipids, cholesterol at high mole ratio, MPLA at defined mole ratios to phospholipids, and a saponin such as QS-21 at low concentration, together providing enhanced immunogenicity with minimal toxicity.
Stated Advantages
The adjuvant formulation displays minimal toxicity from both MPLA and saponin components.
The specified cholesterol concentration (>50 mol%) in liposomes blocks or reduces hemolytic activity of saponins such as QS-21.
Liposome composition modulates the membrane biochemistry to shield toxic components and reduce adverse effects.
The formulation induces potent immune responses, including strong antibody production and Th1-type immunity with increased INF-γ secretion.
Documented Applications
The adjuvant formulation is used in immunogenic compositions such as vaccines comprising immunogens including proteins, recombinant proteins, glycoproteins, peptides, carbohydrates, haptens, whole viruses, bacteria, protozoan, or virus-like particles.
HIV-1 envelope proteins like gp140 are exemplified as immunogens formulated with the adjuvant to generate neutralizing and binding antibodies.
Vaccines for various pathogens including influenza, HIV-1, hepatitis A and B, human papilloma virus, meningococcal meningitis types A, B, and C, tetanus, diphtheria, pertussis, polio, Haemophilus influenzae type B, dengue, foot and mouth disease, typhoid, pneumococcus, Japanese encephalitis virus, anthrax, shingles, malaria, norovirus, and cancer are indicated as potential use cases for the immunogenic formulations.
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