«Sirolimus, also known as rapamycin, is a macrolide compound that is used to coat coronary stents, prevent organ transplant rejection and to treat a rare lung disease called lymphangioleiomyomatosis. It has immunosuppressant functions in humans and is especially useful in preventing the rejection of kidney transplants. It inhibits activation of T cell and B cell by reducing their sensitivity to interleukin-2 (IL-2) through mTOR inhibition.
It is produced by the bacteriumStreptomyces hygroscopicus and was isolated for the first time in 1972 by Surendra Nath Sehgal and colleagues from samples of Streptomyces hygroscopicus found on Easter Island. The compound was originally named rapamycin after the native name of the island, Rapa Nui. Sirolimus was initially developed as an antifungal agent. However, this use was abandoned when it was discovered to have potent immunosuppressive and antiproliferative properties due to its ability to inhibit mTOR. It was approved by the US Food and Drug Administration in September 1999 and is marketed under the trade name Rapamune by Pfizer (formerly by Wyeth).» (wikipedia)