Nov. 23 (Bloomberg) -- A combination of two drugs may alleviate sickness in people who are exposed to high levels of radiation, even when given as much as 24 hours later, a Harvard University study suggests.
Scientists gave radiation-exposed mice an antibiotic and a synthetic version of the human infection-fighting protein BPI, and 80 percent of the animals lived, according to a study published in the journal Science Translational Medicine. The level of radioactivity was fatal to about 95 percent of the rodents within 30 days without treatment.
The research may point toward new treatments for victims of nuclear disasters, such as Ukraine’s Chernobyl and Japan’s Fukushima, or a nuclear attack, the Harvard researchers said. Radiation sickness can increase the body’s susceptibility to bacteria, while decreasing its ability to make white blood cells that help fight off infection. The mice who received both drugs not only had higher survival rates than those receiving one or the other, they also began generating new blood cells more quickly, the study showed.
“That was not expected and quite dramatic,” said study lead author Eva Guinan, an associate professor of radiation oncology at Dana-Farber Cancer Institute and Harvard Medical School in Boston. A rebound in the body’s ability to generate blood means “you limit hospital time, the need for transfusions, and the need for donors, all the difficult logistics.”
The mice were exposed to about 14 times the annual limit of radiation that an adult human should intake each year. Then, 24 hours later, some of the animals were treated with the combination therapy, while others were treated with either an antibiotic or the protein BPI.
The doses the animals received would kill more than half of all humans exposed at that level within 60 days, mostly from infections. Some of that is because the gut lining breaks down, enabling gut bacteria into the bloodstream. The skin also loses its ability to protect against infection, Guinan said.
Because it would be unethical to expose people to the levels of radiation required to test the drugs in humans, the scientists are using the so-called animal rule for approval of new therapies, which require safety studies in a wide variety of animals.
The combination treatment consists of two drugs already used in people, Guinan said. That’s good because it’s impossible to measure how much radiation exposure someone gets afterwards, meaning that many people who are treated with the combo drugs may be healthy.
“If you and I are farmers near Fukushima and we’re worried about how much radiation we’ve had, the hospital can’t tell whether we’ve had trivial radiation or enough that we’ll die, or something in the middle,” Guinan said. “There’s no established means for determining how much radiation you got after the fact.”
--Editors: Bruce Rule, Angela Zimm
To contact the reporter on this story: Elizabeth Lopatto in New York at firstname.lastname@example.org.
To contact the editor responsible for this story: Reg Gale at email@example.com.