Sirolimus is a type of medication classified as an immunosuppressant, primarily used to prevent organ rejection after a transplant surgery. It works by suppressing the body's immune response, thus reducing the risk of the body attacking and rejecting the transplanted organ. Sirolimus is also being studied for its potential therapeutic effects in various other medical conditions, such as certain types of cancer, autoimmune diseases, and vascular diseases. Research in the area of sirolimus focuses on its mechanism of action, efficacy, safety, and potential uses in different medical contexts.