Rapamycin (RPM)

Rapamycin is an immunosuppressant drug used to prevent rejection in organ transplantation; it is especially useful in kidney transplants. It prevents activation of T cells and B cells by inhibiting their response to interleukin-2 (IL-2). Sirolimus is also used as a coronary stent coating. Sirolimus works, in part, by eliminating old and abnormal white blood cells.[citation needed] Sirolimus is effective in mice with autoimmunity and in children with a rare condition called autoimmune lymphoproliferative syndrome (ALPS).

Sirolimus was originally developed as an antifungal agent. However, this use was abandoned when it was discovered to have potent immunosuppressive and antiproliferative properties. It has since been shown to prolong the life of mice and might also be useful in the treatment of certain cancers.