Here is a link to another article about the drug. It is already an FDA approved drug used to treat rejection in transplant patients, which should make it easier for studies to be done.
Rapamycin is a powerful immunosuppressant and would cause more problems than it would cure in its present form if given in significant doses. It is also not new. It was introduced in the late 90's by Wyeth (now part of Pfizer) to prevent transplant rejection... mostly for kidney transplants. It is also used to treat stents that are used to keep arteries open (it prevents platelets from clinging to them).