Sirolimus, also known as rapamycin and sold under the brand name Rapamune among others, is a macrolide compound that is used to coat coronary stents, prevent organ transplant rejection, treat a rare lung disease called lymphangioleiomyomatosis, and treat perivascular epithelioid cell tumor (PEComa). It has immunosuppressant functions in humans and is especially useful in preventing the rejection of kidney transplants. It is a mechanistic target of rapamycin kinase (mTOR) inhibitor that inhibits activation of T cells and B cells by reducing their sensitivity to interleukin-2 (IL-2).It is produced by the bacterium Streptomyces hygroscopicus and was isolated for the first time in 1972, 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 U.S. Food and Drug Administration (FDA) in September 1999. Medical uses
Sirolimus is indicated for the prevention of organ transplant rejection and for the treatment of lymphangioleiomyomatosis (LAM).Sirolimus (Fyarro), as protein-bound particles, is indicated for the treatment of adults with locally advanced unresectable or metastatic malignant perivascular epithelioid cell tumor (PEComa). Prevention of transplant rejection
The chief advantage sirolimus has over calcineurin inhibitors is its low toxicity toward kidneys. Transplant patients maintained on calcineurin inhibitors long-term tend to develop impaired kidney function or even kidney failure; this can be avoided by using sirolimus instead.
High-grade dysplasia represents a more advanced progression towards malignant transformation. Carcinoma in situ, meaning "cancer in place", represents the transformation of a neoplastic lesion to one in which cells undergo essentially no maturation, thus may be considered cancer-like. In this state, epithelial cells have lost their tissue identity and have reverted to a primitive cell form that grows rapidly and with abnormal regulation for the tissue type. However, this form of cancer remains localized, and has not invaded past the basement membrane into tissues below the surface. Invasive carcinoma is the final step in this sequence. It is a cancer which has invaded beyond the basement membrane and has potential to spread to other parts of the body. Invasive carcinoma can usually be treated, but not always successfully. However, if it is left untreated, it is almost always fatal. See also
Dysplasia


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