"Long before it's in the papers"
February 10, 2016


Promising safety results for “lifespan-boosting” drug

Feb. 10, 2016
Courtesy of the Texas 
Biomedical Research Institute
and World Science staff

A drug that has re­cently drawn sci­en­tif­ic at­ten­tion as a life­span-booster—at least in mice—seems to be safe in mon­keys as well, ac­cord­ing to new find­ings that re­search­ers call “en­cour­ag­ing.”

But while the drug, ra­pa­my­cin, may be prom­is­ing, some re­search­ers have cau­tioned against run­away ex­cite­ment.

A Ger­man study from 2013 sug­gested that the com­pound ex­tend­ed life­span only by keep­ing the mice health­ier—not more youth­ful, based on most meas­ures. On the oth­er hand, the orig­i­nal find­ing that ra­pa­my­cin could ex­tend mouse life­span, pub­lished in the July 2009 is­sue of the jour­nal Na­ture, al­so re­ported that the treated mice showed bet­ter phys­i­cal en­dur­ance. 

Re­ported life­span in­creases in mice have ranged from about 3 per­cent to 10.5 per­cent.

Since the 2009 re­port, oth­er re­search has made it un­clear wheth­er the drug is safe as a long-term treat­ment—though it’s already approved by the U.S. Food and Drug Ad­minis­tration to treat organ trans­plant re­jec­tion.

The safety con­cerns helped mo­ti­vate the new stu­dy, us­ing an­i­mals more closely re­lat­ed to peo­ple. This work found that mar­mosets, a spe­cies of mon­key, gen­er­ally tol­er­ated ra­pa­my­cin in cap­sules well af­ter a long-term treat­ment, show­ing min­i­mal met­a­bol­ic side ef­fects.

“This in­i­tial study with mar­mosets as a mod­el for hu­man ag­ing has al­lowed us to eval­u­ate the ef­fi­ca­cy of a new in­ter­ven­tion treat­ment that looked prom­is­ing in oth­er an­i­mal mod­el spe­cies for both healthspan and life­span ex­ten­sion,” said Co­rin­na Ross, lead au­thor of the stu­dy, from Tex­as A&M Un­ivers­ity San An­to­nio.

The stu­dy, by re­search­ers at The Un­ivers­ity of Tex­as Health Sci­ence Cen­ter at San An­to­nio and the South­west Na­t­ional Pri­mate Re­search Cen­ter at Tex­as Bi­o­med­i­cal Re­search In­sti­tute, ap­pears in the No­vem­ber is­sue of the jour­nal Ag­ing.

“The re­sults are encourag­ing,” said Suzette Tardif, As­so­ci­ate Di­rec­tor of the pri­mate re­search cen­ter, a co-in­vest­iga­tor. Based on them, the re­search­ers have also won a $2.7 mil­lion grant from the Na­t­ional In­sti­tute on Ag­ing for a fur­ther stu­dy, look­ing at ra­pa­my­cin’s ef­fects on life­span and mark­ers of healthy ag­ing for mid­dle-aged mar­mosets. 

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A drug that has recently drawn scientific attention as a lifespan-booster—at least in mice—seems to be safe in monkeys as well, according to new findings that researchers call “encouraging.” But while the drug, rapamycin, may be promising, some researchers have cautioned against runaway excitement. A German study from 2013 suggested that the compound extended lifespan only by keeping the mice healthier—not more youthful, based on most measures. On the other hand, the original finding that rapamycin could extend mouse lifespan, published in the July 2009 issue of the journal Nature, also reported that the treated mice showed better physical endurance. Reported lifespan increases in mice have ranged from about 3 percent to 10.5 percent. Since the 2009 report, other research has made it unclear whether the drug is safe as a long-term treatment. This concern helped motivate the new study, using animals more closely related to people. This work found that marmosets, a species of monkey, generally tolerated rapamycin in capsules well after a long-term treatment, showing minimal metabolic side effects. “This initial study with marmosets as a model for human aging has allowed us to evaluate the efficacy of a new intervention treatment that looked promising in other animal model species for both healthspan and lifespan extension,” said Corinna Ross, lead author of the study, from Texas A&M University San Antonio. The study, by researchers at The University of Texas Health Science Center at San Antonio and the Southwest National Primate Research Center at Texas Biomedical Research Institute, appears in the November issue of the journal Aging. “The results are encouraging,” said Suzette Tardif, Associate Director of the primate research center, a co-investigator. “Marmosets also offer a unique non-human primate model that will allow us to further evaluate not just the safety but the effectiveness of treatment with rapamycin.” The researchers have received a $2.7 million grant from the National Institute on Aging for a further study, looking at rapamycin’s effects on lifespan and markers of healthy aging for middle-aged marmosets.