QS-21 is a purified

plant extract An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol, oil or water. Extracts may be sold as tinctures, absolutes or in powder form. The aromatic principles of many spices, nuts, ...

used as a

vaccine adjuvant In immunology, an adjuvant is a substance that increases or modulates the immune response to a vaccine. The word "adjuvant" comes from the Latin word ''adiuvare'', meaning to help or aid. "An immunologic adjuvant is defined as any substance that ...

. It is derived from the

soap bark tree ''Quillaja saponaria'', the soap bark tree or soapbark, is an evergreen tree in the family Quillajaceae, native to warm temperate central Chile. In Chile it occurs from 32 to 40° South Latitude approximately and at up to 2000 m (6500&nbs ...

(''Quillaja saponaria''), which is native to the countries of

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, and

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

. The

crude drug Crude drugs are plant or animal drugs that contain natural substances that have undergone only the processes of collection and drying. The term natural substances refers to those substances found in nature that have not had man-made changes made i ...

(''Quillajae cortex'') is imported from Peru and Chile. The extract contains

water-soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

triterpene Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squale ...

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

s, which are members of a family of plant-based compounds called

saponin Saponins (Latin "sapon", soap + "-in", one of), also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed ...

s. It has been tested as an adjuvant in various

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...

s in attempts to improve their

efficacy Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as ''effectiveness'', and it has often been used synonymously, although in pharmacology a pragmatic clinical trial#Efficacy versu ...

. It is believed to enhance both

humoral Humoral immunity is the aspect of immunity that is mediated by macromolecules - including secreted antibodies, complement proteins, and certain antimicrobial peptides - located in extracellular fluids. Humoral immunity is named so because it invo ...

and

cell-mediated immunity Cell-mediated immunity or cellular immunity is an immune response that does not involve antibodies. Rather, cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in ...

. Isolation of QS-21 destroys the soap bark tree, which has resulted in regulation of the tree by the governments where it is grown. A semi-synthesis strategy relies on purifying the prosapogenin (triterpene and branched trisaccharide) part of the molecule and adding the rest of QS-21 synthetically; this is reported to increase the yield by 2 orders of magnitude. This semi-synthetic approach has also facilitated experimentation with alternative

acyl In chemistry, an acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an alkyl group (). In organic chemistry, the acyl group (IUPAC n ...

chain compositions. QS-21 has undergone clinical evaluation as an additive for various trial vaccines, including those for

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...

and

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

. , it had been tested in more than 3000 patients in 60

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...

s. It is a component of the

Shingrix A zoster vaccine is a vaccine that reduces the incidence of herpes zoster (shingles), a disease caused by reactivation of the varicella zoster virus, which is also responsible for chickenpox. Shingles provokes a painful rash with blisters, and ...

vaccine. QS-21 (Matrix M) is a critical, saponin-derived

immunologic adjuvant In immunology, an adjuvant is a substance that increases or modulates the immune response to a vaccine. The word "adjuvant" comes from the Latin word ''adiuvare'', meaning to help or aid. "An immunologic adjuvant is defined as any substance that ...

for the manufacturing of the

Novavax COVID-19 vaccine The Novavax COVID-19 vaccine, sold under the brand names Nuvaxovid and Covovax, among others, is a subunit COVID-19 vaccine developed by Novavax and the Coalition for Epidemic Preparedness Innovations (CEPI). Full results from Nuvaxovid's pi ...

. The addition of QS-21 triterpene-glycosides in form of

liposome A liposome is a small artificial vesicle, spherical in shape, having at least one lipid bilayer. Due to their hydrophobicity and/or hydrophilicity, biocompatibility, particle size and many other properties, liposomes can be used as drug deliver ...

s is enhancing both humoral and cellular immunogenicity.

Agenus Agenus Inc. is a Lexington, Massachusetts-based biotechnology company focused on immunotherapy including immuno-oncology, a field that uses the immune system to control or cure cancer. The company is developing checkpoint modulators (CPMs), patie ...

Inc. is the sole US-manufacturer of an FDA-approved, patented extract. Supplies are tightly controlled, and the US has invoked the US Defense Production Act to preserve vaccine raw materials for its own companies.Wang Pengfei (March 2021)
"Natural and Synthetic Saponins as Vaccine Adjuvants"
''Vaccines'' 9(3):222. PMID: 33807582 PMCID: PMC8001307 DOI: 10.3390/vaccines9030222.

References

External links

Quillaja extract, other uses
{{Glycosides Adjuvants Saponins Triterpene glycosides

See also

References

External links