Experimental Ebola
drug heals all monkeys in study
An experimental Ebola drug healed all
18 monkeys infected with the deadly virus in a study, boosting hopes that the
treatment might help fight the outbreak raging through West Africa-once more of
it can be made.
The monkeys were given the drug, ZMapp, three to
five days after they were infected with the virus and when most were showing
symptoms. That is several days later than any other experimental Ebola treatment
tested so far.
The drug also completely protected six other
monkeys given a slightly different version of it three days after infection in
a pilot test. These two studies are the first monkey tests ever done on ZMapp.
"The level of improvement was utterly beyond
my honest expectation," said one study leader, Gary Kobinger of the Public
Health Agency of Canada in Winnipeg.
"For animal data, it's extremely
impressive," said Dr. Anthony Fauci, director of the National Institute of
Allergy and Infectious Diseases, which had a role in the work.
It's not known how well the drug would work in
people, who can take up to 21 days to show symptoms and are not infected the
way these monkeys were in a lab.
Several experts said it's not possible to
estimate a window of opportunity for treating people, but that it was
encouraging that the animals recovered when treated even after advanced disease
developed.
The study was published online Friday by the
journal Nature.
ZMapp had never been tested in humans before two
Americans aid workers who got Ebola while working in Africa were allowed to try
it. The rest of the limited supply was given to five others.
There is no more ZMapp now, and once a new batch
is ready, it still needs some basic tests before it can be tried again during
the African outbreak, Fauci said. "We do need to know what the proper dose
is" in people and that it's safe, he said.
Ebola has killed more than 1,500 people this year
and the World Health Organization says there could be as many as 20,000 cases
before the outbreak is brought under control. On Friday, it spread to a fifth
African country — Senegal, where a university student who traveled there from
Guinea was being treated.
There is no approved vaccine or specific
treatment, just supportive care to keep them hydrated and nourished. Efforts
have focused on finding cases and tracking their contacts to limit the disease,
which spreads through contact with blood and other fluids.
ZMapp is three antibodies that attach to cells
infected with Ebola, helping the immune system kill them.
Of the seven people known to have been treated
with ZMapp, two have died — a Liberian doctor and a Spanish priest. The priest
received only one of three planned doses. The two Americans recovered, as have
two Africans who received ZMapp in Liberia — a Congolese doctor and a Liberian
physician's assistant who were expected to be released from a treatment center
on Saturday. A British nurse also got the drug, reportedly the two unused doses
left over from treating the Spanish priest.
Doctors have said there is no way to know whether
ZMapp made a difference or the survivors recovered on their own, as about 45
percent of people infected in this outbreak have.
ZMapp's maker, Mapp Biopharmaceutical Inc., of
San Diego, has said the small supply of the drug is now exhausted and that it
will take several months to make more. The drug is grown in tobacco plants and
was developed with U.S. government support.
Kobinger said it takes about a month to make 20
to 40 doses at a Kentucky plant where the drug is being produced. Officials
have said they are looking at other facilities and other ways to ramp up
production, and Kobinger said there were plans for a clinical trial to test
ZMapp in people early next year.
The monkey study involved scientists from the
Canada health agency, Mapp Biopharmaceutical, the U.S. National Institutes of
Health and the United States Army Medical Research Institute of Infectious
Disease.
Eighteen monkeys were given lethal amounts of
Ebola in a shot, then received three intravenous doses of ZMapp, given three
days apart starting three to five days after they were infected. Some were
showing severe symptoms such as excessive bleeding, rashes and effects on their
liver.
All treated with ZMapp survived; three other
infected monkeys who did not get the drug died within eight days.
Primates have been good stand-ins for people for
many viral diseases, but how well they predict human responses to Ebola,
"we just don't know," said Dr. Cameron Wolfe, a Duke University infectious
disease specialist. The study also "tells us nothing about side
effects" people might have, he added.
Still, it was encouraging that even monkeys with
severe symptoms got better, said Wolfe and Erica Ollmann Saphire, a Scripps
Research Institute professor who has worked with some of the study leaders on
antibodies to Ebola.
"The treatment window in humans needs to be
established in a well-controlled trial" that also would explore the
correct dose of ZMapp in people, Saphire wrote in an email. "Given its
tremendous efficacy in the nonhuman primates, I don't see how it couldn't be
helpful in people."
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