A new study provides strong evidence that the experimental drug given to two American aid workers stricken with Ebola in Africa really works and could make a difference in the current outbreak — if more of it could be produced.
In the study, all 18 monkeys exposed to a lethal dose of Ebola virus survived when given the drug, known as ZMapp, even when the treatment was started five days after infection, when the animals were already sick.
Moreover, the monkeys’ symptoms, such as excessive bleeding, rashes and signs of liver toxicity, eventually disappeared. By contrast, all three monkeys in the control group died.
Experts said these were the best monkey results reported to date for any Ebola drug, raising hopes that the drug will work in people.
Graphic | What You Need to Know About the Ebola Outbreak Questions and answers on the scale of the outbreak and the science of the Ebola virus. “I think it strongly supports that concept,” Gary P. Kobinger, the senior author of the study, said in a telephone news conference Friday, shortly before the paper was published by the journal Nature. Still, Dr. Kobinger, a researcher for the Public Health Agency of Canada, cautioned that effectiveness in monkeys was not “proof” that a drug would work in people.
Kartik Chandran, an expert on Ebola who was not involved in the study, said the results were impressive.
“To actually be able to reverse all those symptoms and signs and bring them back to baseline, I think that is pretty astounding,” said Dr. Chandran, an associate professor of microbiology and immunology at the Albert Einstein College of Medicine. “If you are going to give somebody something during this outbreak, this would be it.”
The problem is that the supply of ZMapp is exhausted, according to Mapp Biopharmaceutical, the nine-person San Diego company that is developing the drug. And it is expected to take months to make more of the drug, which is produced in genetically engineered tobacco plants.
ZMapp came to the world’s attention early this month when it appeared to help two American aid workers stricken in Liberia and later flown to Emory University Hospital in Atlanta. The workers, Dr. Kent Brantly and Nancy Writebol, recovered and were discharged from the hospital last week. [eap_ad_1] Doctors say it is impossible to say what role ZMapp played in their recovery. Nonetheless, there has been a clamor for the drug and an ethical debate about who was entitled to the handful of treatment courses available.
The remaining supplies went to a Spanish priest, three doctors in Liberia and, just this week, a British nurse recovering in London. The priest, Miguel Pajares, and one of the Liberians, Dr. Abraham Borbor, died.
Father Pajares received one of the recommended three doses before he died, and the remainder has gone to the British nurse, William Pooley, according to a person involved in the discussions about drug allocation.
Some other experimental drugs have shown the ability to protect monkeys from Ebola if given shortly after infection, up to about two days. That might make such a drug useful for what is called postexposure prophylaxis — for example, after a person is stuck by an infected needle.
But in an outbreak like the one in Africa, most people do not know they are infected until symptoms develop. Most if not all of the people who have received ZMapp, for instance, were already sick. Hence it would be important that a drug could work even if treatment starts after symptoms appear, as was the case in this study.
Dr. Kobinger, who works at the National Microbiology Laboratory in Winnipeg, Manitoba, said it was difficult to know how that aspect of the monkey results would translate in humans..
People can take up to 21 days to develop symptoms. In the study, the monkeys not given ZMapp died by eight days after infection. He said the next step would be to see if the drug can work even if started six or seven days after exposure, though at some point, the organs would be too damaged to allow for recovery.
ZMapp is a cocktail of three monoclonal antibodies, which are immune system proteins that can isolate and neutralize an invading pathogen. The antibodies were initially harvested from mice exposed to a protein from Ebola, then genetically engineered to make them more like human antibodies.