Cancer Drugs Thwart Ebola In Lab

Cancer Drugs Thwart Ebola In Lab
by Scott Hensley - NPR
March 2, 2012

The Ebola virus causes a hemorrhagic fever that can be deadly.

Ebola is one virus you never want to catch. Ever.

After some aches and a fever, many infected people develop uncontrolled bleeding. The mortality rates from Ebola infection can run as high as 90 percent.

There's no cure for Ebola. But a group of scientists is exploring whether some drugs already approved to treat cancer might help tame the virus.

Sounds wild. But there's a reason — and now some evidence — to think it might work.

To reproduce, the Ebola virus needs the help of cells it invades. And a couple of cancer drugs tweak a human protein that new copies of the virus use to leave their host cells so they can infect others.

The tested drugs — Gleevec and Tasigna, both sold by Novartis — are called tyrosine kinase inhibitors. Tyrosine kinases are enzymes that put a phosphate group on a particular amino acid. Amino acids, as you might remember from high school biology, are the building blocks of proteins.

When a phosphate group gets attached to the right tyrosine block on the right protein, it changes the shape and function of the protein. And that might change everything when it comes to Ebola.

"Proteins are like little machines," says Emory University's Dan Kalman, one of the researchers. "As with a machine, they can be turned or turned off. The switch for turning things on or off is a modification. And one of those modifications is a phosphate group."

In some cancers, the tyrosine kinases help trigger the uncontrolled division of cells. Gleevec and Tasigna help stop that.

When it comes to Ebola, the researchers think drugs like these could turn off a transport protein and could keep new viruses bottled up inside cells.

The Ebola lab work using collections of human cells was published in the latest issue of Science Translational Medicine. It showed that the drugs dramatically decrease the ability of Ebola to replicate. "The effect was quite pronounced," Kalman told Shots.

And, if the theory holds, such a reduction might be enough to allow an infected person's immune system to mop up the Ebola viruses.

"Ebola is a very nasty infection," Kalman says. "The whole concept of containing the disease in a local group before it spreads all over the planet is something clearly we want to do."

The next step will be to see if the drugs can make a difference in animal experiments.