Sanofi Pasteur, the vaccines business of France’s Sanofi-Aventis, has licensed an adjuvant technology from Japan’s Eisai that could boost the efficacy of a broad range of human vaccines.

Adjuvants – used to boost the immunogenicity of vaccine antigens – have been used for decades, but until recently there has been little R&D to find new types of adjuvant. For years, alum was the only vaccine adjuvant approved for human use, although another, GlaxoSmithKline/Corixa’s MPL, reached the market earlier this year in an improved version of its Engerix-B hepatitis B vaccine [[03/03/05c]].

Meanwhile, in addition to boosting immunogenicity, there is a need for new adjuvants to overcome several drawbacks with alum, including irritation and inflammation at the injection site and limited utility in vaccines against intracellular pathogens. And as countries struggle to stockpile vaccines against the threat of a flu pandemic, there has been interest in using adjuvants to boost the number of doses that can be teased out of each production batch of vaccine antigen.

Eisai’s adjuvant, E6020, is a chemically synthesised TLR-4 (Toll-like receptor-4) agonist that stimulates the host's natural immunity. It will be used in Sanofi Pasteur’s new vaccine products. The French company has licensed the adjuvant on a non-exclusive basis around the world, and will pay Eisai upfront, milestone and royalty payments on vaccines that use the ingredient.