Positive results for phase II malaria vaccine
pharmafile | September 16, 2011 | News story | Research and Development | malaria, malaria vaccine
Researchers in the US and West Africa believe they have identified the first effective blood-stage malaria vaccine, a development which would be a major step forward in prevention of the disease.
Scientists from the University of Maryland School of Medicine, working with the University of Bamako in Mali, say such a jab would kill the malaria parasite as it emerges from the liver into the bloodstream.
A phase II trial of the candidate vaccine FMP2.1/AS02A in Mali, reported in the New England Journal of Medicine, found that paediatric patients who received it were well protected against parasites that had a similar genetic make-up to the malaria strain used in the drug.
“This trial is the first good news that we have had in a long while for blood-stage vaccines,” says senior author Christopher Plowe, leader of the malaria group at Maryland.
Malaria is passed on by a parasite injected through the bite of an infected mosquito. This new vaccine is based on a single strain of the Plasmodium falciparum malaria parasite – the most common in Africa – and consists of a malaria protein, AMA1, from its blood stages.
This is combined with an adjuvant compound that boosts the immune response to the vaccine, which was developed and manufactured by GlaxoSmithKline Biologicals.
The vaccine was 64% protective for children in the trial who were infected with a parasite with similar AMA1 to that of the parasite in the vaccine, Plowe explained.
“No other blood-stage vaccine has shown any detectable efficacy against clinical malaria,” he added. “The fact that we saw this partial protection against malaria has reinvigorated the entire field.”
The point of concentrating on the blood stage is to prevent the parasite from multiplying inside red blood cells, thus causing disease and death by sticking to the insides of blood vessels in the brain and other organs.
RTS,S/AS01, the most advanced current malaria vaccine, attacks an earlier stage of the parasite, and has about 50% protective efficacy. Combining it with an effective blood stage vaccine could produce the protection necessary to eradicate the disease, scientists hope.
The trial opens the door to a potential malaria vaccine which might resemble the one currently used to treat polio, which brings together three specific strains of the disease to create broad immunity.
The fight against malaria is ongoing in laboratories across the world: it is one of the diseases high on the agenda at GSK’s own ‘open lab’ near Madrid, for example, while in May Sanofi signed a research deal with the Medicines for Malaria Venture charity.
There are more than 300 million cases of the disease worldwide each year, many of them in Africa, and more than 800,000 people die from it.
Adam Hill
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