Rapamycin has been shown to modestly extend life in mice, though there is some ongoing debate as to whether this is an effect caused by cancer risk reduction rather than a slowing of aging. Some researchers are now intending to embark on a small study using dogs:
Yeast, worms and mice: all have lived longer when treated with various chemical compounds in laboratory tests. But many promising leads have failed when tried in humans. This week, researchers are proposing a different approach to animal testing of life-extending drugs: trials in pet dogs. Their target is rapamycin, which is used clinically as part of an anti-rejection drug cocktail after kidney transplants and which has also been shown to extend the lives of mice by 13% in females and 9% in males.
The compound's effect on lifespan has not yet been tested in people - human trials are expensive and it takes a long time to learn whether a drug can extend a human life. Furthermore, rapamycin is no longer patentable, so pharmaceutical companies are unwilling to invest effort in it. The drug can also cause some serious side effects that might rule it out as a pharmaceutical fountain of youth. It has, for example, been linked to an increased risk of diabetes in people who have had kidney transplants. But at low doses, researchers suspect that the drug will not be a problem for healthy dogs.
[Molecular biologists] propose to give low doses of rapamycin to dogs in a study that would also test whether the drug can extend the animals' lives. The researchers hope to test rapamycin in large dogs that typically live for eight to ten years; they would start giving the drug to animals aged six to nine. A pilot trial would involve about 30 dogs, half of which would receive the drug, and would allow the researchers to dose the dogs for a short time and observe effects on heart function and some other health measures. The trial could be completed in as little as three years, but researchers will know long before that - perhaps in months - whether rapamycin improves cardiac function or other aspects of health.