Saturday, July 14, 2018

Drug to Treat Smallpox Approved by F.D.A., a Move Against Bioterrorism

Drug to Treat Smallpox Approved

Drug to Treat Smallpox Approved by F.D.A., a Move Against Bioterrorism

The Food and Drug Administration on Friday approved the primary drug intended to treat smallpox — a move that would halt a lethal pandemic if the virus were to be released as a terrorist bioweapon or through a laboratory accident.

The antiviral pill, tecovirimat, also referred to as Tpoxx, has never been tested in humans with smallpox because the disease was declared eradicated in 1980, three years after the last known case.

But it had been very effective at protecting animals deliberately infected with monkeypox and rabbitpox, two related diseases which will be lethal.

It also caused no severe side effects when safety-tested in 359 healthy human volunteers, the F.D.A. said.

“This new treatment affords us a further option should smallpox ever be used as a bioweapon,” said Dr. Scott Gottlieb, the F.D.A.’s commissioner.

Having a drug that sometimes cures smallpox is a crucial medical breakthrough, according to several doctors not related to the F.D.A. or the corporate making the drug.

F.D.A. approval is “definitely an honest thing,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.

Research on tecovirimat — originally designated ST-246 — began at the institute after the 9/11 surprise attack on the planet Trade Center, Dr. Fauci said.

The research accompanied efforts to stretch the national stockpile of smallpox vaccine by safely diluting it.

“It all started some time past, but developing a licensed product took until today,” he added.

The F.D.A. approval of the drug visited Siga Technologies of Corvallis, Ore., a private company that developed the drugs under a federal biomedical defense contract.

Although circulating smallpox has been eradicated, two known stores of the virus exist in laboratory freezers — one in Russia and one at the Centers for Disease Control and Prevention in Atlanta.

Bioterrorism experts fear that other stocks may exist; for instance, in 2014 several forgotten vials containing smallpox were found at the National Institutes of Health.

More worrisome, experts say, is that the possibility that a terrorist lab or maybe a classy amateur could use modern gene-editing techniques to rebuild the virus then unleash it, deliberately or accidentally, on an unprepared world.

Because routine smallpox vaccination stopped after 1980, almost everyone under the age of 40 is unprotected. The disease kills almost a 3rd of individuals who catch on and is even more lethal to babies.

Finding a drug was vital because — unlike, for instance, measles or pertussis vaccine — smallpox vaccine is just too dangerous to offer everyone, said Dr. Peter J. Hotez, former president of the Sabin vaccine Institute and dean of the National School of Tropical Medicine at Baylor College of Drugs.

The vaccine is now routinely given only to some members of the military, lab workers, and others likely to return in touch with the virus during a bioterrorism event.

It can't be given to pregnant women, or anyone with H.I.V., under cancer treatment or with any other immunosuppressive condition; nor can the vaccine tend to anyone with eczema or several other skin diseases, Dr. Hotez said.

So drugs like tecovirimat would be useful for treating anyone infected within the first wave of any release of the virus, also because of the many Americans who can't be vaccinated.

Dr. William Schaffner, a professor of medicine at Vanderbilt University Medical School, noted tecovirimat also might be useful for treating monkeypox, which infects humans and has been increasing rapidly in Africa since smallpox vaccination ended.

Monkeypox sometimes travels internationally; in 2003, there was an epidemic of 47 confirmed and suspected cases within us.

consistent with the C.D.C., the virus arrived during a shipment of 800 small mammals from Ghana, including African giant pouched rats and cord squirrels intended for the pet trade.

They infected prairie dogs at an Illinois pet warehouse; the prairie dogs successively infected children who bought them as pets.

Despite its fearsome reputation, smallpox spreads slowly compared with more common diseases like measles or chickenpox, Dr. Schaffner said.

Symptoms like fever, exhaustion, and headache typically begin 10 to 14 days after infection. These are followed by a rash of small bumps that become pus-filled sores, which can cause permanent scarring.

In severe cases, the infection causes the loss of huge areas of skin and bleeding. The virus can also reach the brain, resulting in encephalitis, and may cause blindness by blistering the eyeballs.

When tecovirimat was tested in humans, the foremost common side effects it caused were headache, nausea, and abdominal pain, the F.D.A. said.

Results of testing by Siga Technologies were published in the New England Journal of Medicine on July 5.

The F.D.A. gave Siga several valuable incentives toward its application for approval, including fast-track and priority review designations.

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