VO Banner
Search: for Help
Vaxjo Home
News and Updates
Vaxjo Query
Selected Adjuvants
adamantylamide dipeptide vaccine adjuvant
aluminum hydroxide vaccine adjuvant
alhydrogel vaccine adjuvant
Data Submission
Data Exchange
Data Download
Contact Us


Vaxjo ID 71
Vaccine Adjuvant Name QS-21
Alternative Names Stimulon™ QS-21 Adjuvant.
Adjuvant VO ID VO_0001310
Description Used in vaccine formulations as a primary adjuvant component for enhancement of both humoral and cell-mediated immunity. Water soluble. No emulsification required. Can be used alone or combined with aluminum hydroxide adjuvant (Vogel and Powell, 1995).
Stage of Development Clinical Trial
Components Natural product of the bark of the Quillaja saponaria Molina tree (species native to Chile and Argentina). Extracted from the bark by aqueous extraction. Purified by normal phase and reverse phase chromatography (Vogel and Powell, 1995).
Molecular Weight Parent: 1990, so
Appearance Solid: white odorless powder. Aqueous solution: clear, colorless solution (Vogel and Powell, 1995).
Storage Store solid QS-21 under low humidity conditions at -20° C. Protect from light. Optimum storage conditions are under evaluation. No apparent degradation under low humidity conditions after storage at 25° C for three years. Aqueous solutions are optimally stable between pH 5 to 7 and in micellar form. Solutions of QS-21 in 0.5 mg/mL solution may be stored in this pH range at 5° C for two or three years. QS-21 is less stable at lower concentrations; HPLC analysis is recommended for analysis of any new vaccine formulation. Protect from light. In aqueous solution, the fatty acid ester bond migrates between the 3 and 4 position on fucose, with the ester at the 4 position being favored. Both forms are active as adjuvants. Primary degradation reaction is alkaline hydrolysis of the fatty acid ester bond at the 3 or 4 position on fucose. Due to alkaline-catalyzed degradation reaction, sterilization should be carried out by membrane filtration instead of autoclaving (Vogel and Powell, 1995).
Function Shown to stimulate humoral immune responses in mice, including antigen-specific IgG1, IgG2b and IgG2a titers. Most QS-21 formulations in mice have been administered by the subcutaneous or intramuscular route, but intranasal and oral administration have also been shown to be effective. Augments production of IgG responses to ganglioside antigen in melanoma vaccine in human Phase I clinical trials. Augments protective benefit of a recombinant malaria vaccine in human Phase I clinical trials.Shown also to stimulate CTL responses in mice (Vogel and Powell, 1995).
Safety QS-21 has been entered in a Phase III trial of a therapeutic melanoma vaccine at 100 μg QS-21 per dose. QS-21 has been evaluated in Phase I and II trials of 31 different vaccines over a QS-21 dose range of 25 to 100 μg. At present, over 1500 individuals have received QS-21 adjuvanted vaccines (Vogel and Powell, 1995).
Related Vaccine(s)
Vogel and Powell, 1995: Vogel FR, Powell MF. A compendium of vaccine adjuvants and excipients. Pharmaceutical biotechnology. 1995; 6; 141-228. [PubMed: 7551218].