Can a pill make you younger? One of the few drug studies ever carried out in an attempt to address this question was reported by Novartis on Christmas Eve 2014. The company had sought to see whether giving low doses of a drug called everolimus to people over 65 increased their response to flu vaccines. It did, by about 20 percent. Yet behind the test was a bigger question about whether any drug can slow or reverse the symptoms of old age. Novartis's study on everolimus, which looked at whether the immune system of elderly people could be made to act younger, has been called the "first human aging trial." Last week a Boston company, PureTech Health, said it was licensing two drug molecules, and the right to use them against aging-related disease, from Novartis and making the research the basis of a startup company, resTORbio. The company says it will further test whether such drugs can rejuvenate aged immune cells. The drug Novartis tested is a derivative of rapamycin, a compound first