SEATTLE/LONDON
(Reuters) - An experimental vaccine from GlaxoSmithKline
halved the rick of African children getting malaria in a major clinical trial,
making it likely to become the world's first shot against the deadly disease.
Final-stage trial data released on Tuesday showed it gave protection
against clinical and severe malaria in 5-17 month-olds in Africa,
where the mosquito-borne disease kills hundreds of thousands of children a
year.
"These
data bring us to the cusp of having the world's first malaria vaccine,"
said Andrew Witty, chief executive of the British drugmaker that developed the
vaccine along with the nonprofit PATH Malaria Vaccine Initiative (MVI).
While
hailing an unprecedented achievement, Witty, malaria scientists and global
health experts stressed that the vaccine, known as RTS,S or Mosquirix, was no
quick fix for eradicating malaria. The new shot is less effective against the
disease than other vaccines are against common infections such as polio and
measles.
"We
would have wished that we could wipe it out, but I think this is going to
contribute to the control of malaria rather than wiping it out," Tsiri
Agbenyega, a principal investigator in the RTS,S trials in Ghana, told Reuters at a Seattle, Washington,
conference about the disease.
Malaria
is endemic in around 100 countries worldwide and killed some 781,000 people in
2009, according to the World Health Organization.
Control
measures such as insecticide-treated bednets, indoor spraying and use of
combination anti-malaria drugs have helped significantly cut the numbers of
malaria cases and deaths in recent years, but experts have said that an
effective vaccine is vital to complete the fight against the disease.
The
new data, presented at the Bill & Melinda Gates Foundation's Malaria Forum
conference in Seattle and published simultaneously in the New England Journal
of Medicine, were the first from a final-stage Phase III clinical trial
conducted at 11 trial sites in seven countries across sub-Saharan Africa.
The
trial is still going on, but researchers who analyzed data from the first 6,000
children found that after 12 months of follow-up, three doses of RTS,S reduced
the risk of children experiencing clinical malaria and severe malaria by 56
percent and 47 percent, respectively.
"We
are very happy with the results. We have never been closer to having a
successful malaria vaccine," said Christian Loucq, director of PATH MVI,
who was at the conference.
Loucq
said widespread use of insecticide-treated bednets in the trial -- by 75
percent of people taking part -- showed that RTS,S can provide significant
protection on top of other existing malaria control methods.
Results
in babies aged six to 12 weeks are expected in a year's time and, if all goes
well, GSK believes the vaccine could reach the market in 2015.
COSTS
Getting
RTS,S to African infants who need it will take a concerted effort from
international funders such as the Gates Foundation, which helped pay for the
research. Health experts have said it must be cheap enough to be
cost-effective.
Gates
said the results were a "huge milestone" in the fight against
malaria.
Witty
declined to say if a course of three shots would cost under $10 but told
reporters RTS,S would be priced as low as possible. The company has previously
said it would charge only the cost of manufacturing it plus a 5 percent
mark-up, which would be reinvested into tropical disease research. "We are
not going to make any money from this project," Witty said.
However,
shares in GSK's small U.S.
biotech partner Agenus, which makes a component of the vaccine, rose more than
40 percent after news of the clinical trial result.
Britain's minister for international development Andrew
Mitchell said the vaccine "offers real hope for the future."
"An
effective, long-lasting and cost-effective vaccine would make a major
contribution to malaria control," he told the conference.
Malaria
is caused by a parasite carried in the saliva of mosquitoes. The RTS,S vaccine
is designed to kick in when the parasite enters the human bloodstream after a
mosquito bite. By stimulating an immune response, it can prevent the parasite
from maturing and multiplying in the liver.
Without
that immune response, the parasite gets back into the bloodstream and infects
red blood cells, leading to fever, body aches and in some cases death.
RTS,S's
co-inventor Joe Cohen said the data were robust and consistent with earlier
trials, which also showed around 50 percent efficacy. Side effects, including
fever and injection-site swelling, were similar in children given RTS,S and a
control vaccine.
After
working for 24 years on developing the shot, he said he was "very proud of
what we have achieved.
Some
external commentators were cautious about the vaccine's potential, but said it
was an important development that should save many lives. Health experts
normally like to see a success rate of 80 percent plus in a vaccine.
"We're
probably not there yet, but this is a really important advance in
science," Peter Agre, director of the John Hopkins Malaria Research
Institute and a former Nobel prize winner, told Reuters at the conference.
In
an editorial in the New England Journal of Medicine, Nicholas White of Thailand's Mahidol University
said, "It is becoming increasingly clear that we really do have the first
effective vaccine against a parasitic disease in humans."
