If you cut a mouse's daily calorie intake by 30%, it will live at least 30% longer than its normal two-year life span. Some say this is because the body under stress produces protective substances. The trick works with worms and fruit flies, too, and would probably extend life in humans, scientists believe. But we'd all have to learn how to eat just enough to stay alive. This isn't about forgoing Girl Scout Cookies or three-course meals: A true anti-aging diet could be pure torture.
A handful of biotech companies are developing drugs that produce the effects of such "caloric restriction" in the body without depriving people of food. Anti-aging doctors would love to prescribe a medication that would extend their patients' life spans to 125 years -- extrapolating from mice. But companies would have no avenue for seeking Food & Drug Administration approval for such a treatment. "It would be undoable," says Stephen J. Hoffman, an investor in anti-aging biotech Sirtris Pharmaceuticals in Cambridge, Mass., who also sits on its board.
That's because it would take a half-century and countless billions of dollars to prove that the drugs extend life in healthy people, he says. Instead, Sirtris and other startups plan to test their products in diseases common in older people, such as diabetes and obesity, where it's relatively easy to obtain data that the FDA can scrutinize.
Sirtris is focusing on genes that make enzymes called sirtuins, hence the company name. Scientists have found that by making sirtuins more active, they can mimic the effects of caloric restriction. The company hopes to start testing pills containing sirtuin-enhancing chemicals on patients with diabetes, Huntington's disease, and other ailments as early as 2007.
Elixir Pharmaceuticals, also in Cambridge, hopes to reap the benefits of caloric restriction by turning off part of the fat-gathering mechanism. Specifically, the biotech is attacking ghrelin, a protein released in the stomach that makes us feel the urge to eat. A drug that prevents the body from using ghrelin may help patients lose weight, process sugar more effectively, and raise their ratio of muscle to fat.
Elixir cannot go to the FDA with an anti-aging proposition any more than Sirtris can. So the company's more practical goal is to get its drugs approved to treat diabetes and obesity. Human trials could start within two years. "We weren't out to discover the fountain of youth, though lots of people would like us to do that," says Peter DiStefano, Elixir's chief scientific officer.
Regardless of what diseases the FDA approves these drugs to treat, the links between the worlds of biotech and anti-aging medicine are likely to become more intimate. The biotech drug human growth hormone is already a favorite tool of anti-aging doctors. Of the new treatments, "90% will have applications to anti-aging medicine," predicts Dr. Ronald M. Klatz, president of the American Academy of Anti-Aging Medicine. "They're not youth pills, but they offer ways of intervening in the specific mechanisms of aging."
Venture capitalists are taking notice. Sirtris, founded in 2004, has raised $45 million in private funding so far. Six-year-old Elixir has picked up $56 million. Both firms say they've detected some interest on the part of Big Pharma, although no deals have been signed yet. The pioneers of this new science hate to be painted as the Ponce de Leóns of the drug industry. For one thing, the explorer never managed to find his precious fountain. Perhaps he was a few hundred years ahead of his time.