Lifespan extension in mice
Rapamycin was first shown to extend lifespan in eukaryotes in 2006. Powers et al.. showed a dose-responsive effect of rapamycin on lifespan extension in yeast cells. Building on this and other work, in a 2009 study, the lifespans of mice fed rapamycin were increased between 28 and 38% from the beginning of treatment, or 9 to 14% in total increased maximum lifespan. Of particular note, the treatment began in mice aged 20 months, the equivalent of 60 human years. This suggests the possibility of an effective antiaging treatment for humans at an already-advanced age, as opposed to requiring a lifelong regimen beginning in youth. Rapamycin has subsequently been shown to extend mouse lifespan in several separate experiments, and is now being tested for this purpose in nonhuman primates (the marmoset monkey), and with an ongoing attempt to organize a study in dogs.
Because rapamycin at high doses can suppress the immune system, people taking rapamycin for transplant or cancer therapy are more susceptible to dangerous infections. Yet paradoxically, rapamycin was shown to enhance the ability of aging mice to mount an immune response to a vaccine against tuberculosis. A similar immunological "rejuvenating" effect was later documented in elderly humans administered a rapamycin analog prior to influenza vaccination), further fueling optimism for the potential of mTOR as a target for anti-aging drugs for humans.
However, is not known whether rapamycin will have similar lifespan-lengthening effects in humans, and study authors caution that the drug should not be used by the general population for this use.