Leuprolide (leuprorelin) is a peptide analog of gonadotropin-releasing hormone (GnRH) that binds and activates the GnRH1 receptor. Leuprorelin modulates fertility by stimulating release of reproductive hormones. Leuprorelin also prevents stress-induced immunosuppression in animal models. Additionally, leuprorelin exhibits anticancer activity, inhibiting proliferation of prostate cancer cells in vitro. Leuprorelin also inhibits proliferation of endometrial cancer cells by suppressing expression of human telomerase reverse transcriptase (hTERT). In endometrial cells, leuprorelin induces apoptosis by increasing levels of Bax and FasL and decreasing levels of Bcl-2. Leuprorelin also exhibits anti-angiogenic activity, decreasing production of VEGF-A and IL-1β in endothelial cells.