QS-21 Stimulon® Adjuvant
QS-21 Stimulon is designed to turbocharge vaccines by strengthening and broadening immune responses (both T cell and antibody mediated) to a vaccine’s antigens. It is a key component of the most advanced next-generation adjuvant systems being developed by our corporate partners.
QS-21 Stimulon is a saponin extracted from the bark of the Quillaja saponaria (soap bark) evergreen tree native to warm temperate central Chile and purified using Agenus’ proprietary process. The adjuvant has been widely studied in over 120 clinical trials involving approximately 50,000 healthy volunteers and patients, and has consistently demonstrated powerful immune responses and a favorable safety profile.
In October 2015, results of GlaxoSmithKline’s (GSK’s) malaria vaccine study containing Agenus’ QS-21 Stimulon, reported a 50% risk reduction for children under five years of age. Most of the nearly 600,000 estimated annual deaths from malaria are African children under five years of age. In July 2015, GSK received a positive opinion for its malaria vaccine candidate from the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA). The vaccine candidate, named Mosquirix™ (RTS,S) contains Agenus’ QS-21 Stimulon and is the first product containing QS-21 Stimulon to receive a positive regulatory decision. The positive opinion signals that Mosquirix meets the necessary quality, safety and efficacy requirements according to EU standards. Mosquirix is currently awaiting final clearances from the World Health Organization and African Health authorities. Clinical data supporting the vaccine’s safety, efficacy and quality profile were primarily observed in GSK’s Phase 3 clinical program involving more than 16,000 infants and young children.
In October 2015, GSK reported that its shingles vaccine candidate, which contains Agenus’ QS-21 Stimulon® adjuvant, demonstrated 90% overall efficacy against shingles compared to placebo in a second pivotal Phase III trial. In this trial, the GSK vaccine candidate, Shingrix™ was studied in adults aged 70 years and older. These results are consistent with the first pivotal Phase III trial, ZOE-50, which demonstrated an efficacy of 97.2% in adults age 50 years and older. In ZOE-50, 53% of the subjects were over 60, and almost 24% were over 70 years of age. Risk of developing shingles – a painful, itchy rash caused by reactivation of latent chicken pox virus that can result in serious complications – rises sharply after age 50. Lifetime risk is approximately one in three people. GSK plans to begin regulatory submissions for Shingrix for the prevention of shingles in people aged 50 years and above in the second half of 2016.
In September 2015, Agenus partially monetized its potential royalty stream from GSK through a $100M non-dilutive royalty transaction with an investor group led by Oberland Capital.