December 14, 2001
Antigenics' Immune Adjuvant Shows
Benefit In Preventing Malaria In Randomized Trial
- Antigenics Inc. announced today the publication of clinical results of a
malaria vaccine containing the company's immune response enhancer, QS-21,
which showed significant protection against the most widespread and
dangerous forms of malaria. The study, published in the December 8 issue of
The Lancet, is titled "Efficacy of RTS,S/AS02 malaria vaccine against
Plasmodium falciparum infection in semi-immune adult men in The Gambia: a
GlaxoSmithKline Biologicals (GSKB) is developing the vaccine for the
treatment of malaria. Currently named RTS,S/AS02, it is produced by
combining a malaria antigen with an adjuvant formulation that contains
In the 250 men who completed the study in The Gambia, West Africa, the
vaccine was found safe and immunogenic. It induced strong antibody responses
to circumsporozoite protein and strong T-cell responses. This is the first
pre-erythrocytic vaccine to show significant protection against natural P.
The effectiveness of QS-21 has been evaluated in approximately 50 Phase I,
II and III trials involving more than 3,000 patients. QS-21 has been shown
to enhance the quality and quantity of the immune response to a variety of
antigens including those associated with malaria. Specifically, in a study
published in the New England Journal of Medicine, January 9, 1997,
researchers from the Walter Reed Army Institute of Research in Washington,
DC and SmithKline Beecham Biologicals found that the RTS,S vaccine combined
with QS-21 protected against experimental challenge with P falciparum
parasites in six of seven patients. The RTS,S vaccine alone protected only
two of seven patients and the vaccine combined with alum (another adjuvant)
only protected one patient of eight from contracting malaria.
QS-21 is also a key component in several other vaccines under development
including Elan/American Home Product's AN-1792 for Alzheimer's Disease and
VaxGen's product for HIV.
Malaria is an acute and chronic parasitic disease caused by the protozoan
parasites of the genus Plasmodium and spread by the bite of the female
Anopheles mosquito. P falciparum is the most widespread and dangerous of the
malaria parasites, as it is responsible for most of the severe forms of the
disease, as well as the majority of the deaths. The incidence of malaria is
estimated to be between 300 and 500 million clinical cases each year.
Furthermore, malaria accounts for more than 1 million deaths each year. In
particular, malaria is a significant cause of infant and juvenile mortality,
causing approximately 800,000 deaths in children under the age of five
annually. Although the disease was previously widespread, malaria now occurs
primarily in Africa, Asia and South and Central America.