In a late-stage trial of 6,000 children, three doses of GlaxoSmithKline's malaria vaccine RTS,S (also known as Mosquirix) cut the risk of children contracting malaria in a follow-up conducted 12-months after subjects received the last dose of the vaccine. The results set RTS,S up to become the world's first vaccine against the disease, which kills 800,000 people each year.
The vaccine reduced the risk of children experiencing clinical malaria by 56% and severe malaria by 47%. Data were collected from children between 5 and 17 months old; the study is still ongoing in babies 6 to 12 weeks old, with data expected by the end of 2012. More information on the longer-term protective effects of the vaccine after 30 months will be availably by the end of 2014. The data were presented at the Malaria Forum hosted by the Bill & Melinda Gates Foundation and published in The New England Journal of Medicine.
RTS,S, developed in GSK's labs in the late 1980s, works by alerting the immune system to defend against the Plasmodium falciparum malaria parasite when it first enters the bloodstream and/or when the parasite infects liver cells. The PATH Malaria Vaccine initiative, with the help of funding from the Gates Foundation, partnered with GSK in 2001 to study the vaccine in children in sub-Saharan Africa.
GSK's announcement was also good news for Lexington, MA-based Agenus, whose immune-boosting plant extract GSK used in the development of RTS,S.
"These data bring us to the cusp of having the world's first malaria vaccine, which has the potential to significantly improve the outlook for children living in malaria endemic regions across Africa," noted GSK CEO Andrew Witty in a release. "The addition of a malaria vaccine to existing control interventions such as bed nets and insecticide spraying could potentially help prevent millions of cases of this debilitating disease."