“The chemical structure of QS-21, consists of a quillaic acid triterpene (black) substituted with a branched trisaccharide (blue) and a linear tetrasaccharide (green), which is in turn connected to an acyl chain (red) via a hydrolytically labile ester. QS-21 is a 65:35 mixture of the Apiose- and the Xylose-substituted variants of the above molecule”.

QS-21 Overview

QS-21 is the “Gold Standard” adjuvant for enhancing the immune response to vaccine antigens and is supported by over 20 years of scientific research including extensive clinical tested and use in over 1 million humans.

Quillaja saponins are well-known to induce strong activation of both the cell-mediated (Th1) and the humoral arms (Th2) of the immune system. Moreover, quillaja based adjuvants stimulate cytotoxic T-Cell production against exogenous antigens thus providing an enhanced immune response. This is a clear differentiator and significant benefit versus most adjuvants on the market today, including aluminum-based, that mainly activate only humoral immune response. 

QS-21 is currently being utilized and FDA-approved in GSK’s Shingrix® shingles vaccine and GSK’s Mosquirix® malaria vaccine. Its also being used in Novavax’s SARs-CoV-2 (Covid-19) vaccine. 

Additionally, there are three Phase 3 clinical trials for non-small cell lung cancer (NSCLC), herpes zoster and melanoma and is a vital component in more than 17 human vaccine candidates including the following conditions: Alzheimer’s disease, HIV, tuberculosis, Varicella Zoster and other cancer-type vaccine programs.