Transplant drug helps mice live longer

WASHINGTON - By Maggie Fox, Health and Science Editor

An antibiotic pill originally developed to help prevent rejection in organ transplant patients helps mice live longer and might offer a route to fighting age-related disease in people, U.S. researchers reported on Monday.

The drug, called rapamycin or sirolimus and marketed under the brand name Rapamune by Wyeth, suppresses the immune system but also fights inflammation, which underlies cancer, heart disease, Alzheimer's disease and a range of other ills.

"Rapamycin may extend lifespan by postponing death from cancer, by retarding mechanisms of aging, or both," David Harrison of The Jackson Laboratory in Bar Harbor, Maine and colleagues wrote in their report, published in the journal Nature.

Overall, it extended the lives of adult female mice by 14 percent and males by 9 percent, they found.

"We believe this is the first convincing evidence that the aging process can be slowed and lifespan can be extended by a drug therapy starting at an advanced age," said Randy Strong, of the University of Texas Health Science Center at San Antonio, who worked on the study.

That does not mean people can start taking the powerful drug as an anti-aging pill, said Dr. Lynne Cox of Britain's University of Oxford.

"While the lab mice were protected from infection, that's simply impossible in the human population," Cox said in a statement.

Mice also live much shorter lives than human beings and do not always age in the same way biologically.

FIGHTING AGING

But the finding could help researchers find better ways to fight the diseases of aging and perhaps the process itself.

"What the study does is to highlight an important molecular pathway that new, more specific drugs might be designed to work on," Cox said.

The researchers at several U.S. centers fed rapamycin capsules to the mice daily starting at the age of 600 days, an age equivalent to 60 years old in humans.

All the mice lived longer, they reported. Some lived as much as 55 percent longer, but the effects varied.

"I never thought we would find an anti-aging pill for people in my lifetime; however, rapamycin shows a great deal of promise to do just that," said Arlan Richardson, director of the Barshop Institute at the University of Texas.

Rapamycin was found in soil from Easter Island, the Pacific Ocean island best known for its giant stone carved heads. Its name comes from the island's Polynesian name, Rapa Nui.

Rapamycin shuts down the same molecular pathway as restricting food intake or reducing growth factors, via mTOR -- for mammalian target of rapamycin, a cell protein that helps control metabolism and responses to stress.

"If rapamycin, or drugs like rapamycin, works as envisioned, the potential reduction in overall health cost for the U.S. and the world will be enormous," Strong said.

Rapamycin is used on stents, the mesh tubes that help hold open previously clogged arteries, and is being investigated as a treatment for cancer and autism.

In January GlaxoSmithKline signed a deal with privately held British biotech company Biotica Technology, that works with compounds known as rapamycin analogs. Wyeth is being acquired by Pfizer Inc..

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