giredestrant + palbociclib + luteinizing hormone-releasing hormone agonist

This is a three-drug **combination regimen** consisting of **giredestrant** (an oral, next-generation selective estrogen receptor degrader [SERD]), **palbociclib** (an oral cyclin-dependent kinase 4 and 6 [CDK4/6] inhibitor), and a **luteinizing hormone-releasing hormone agonist** (LHRH agonist; also known as a gonadotropin-releasing hormone agonist). The regimen is under investigation for the treatment of **estrogen receptor-positive (ER+), HER2-negative breast cancer**, particularly in premenopausal and peri-menopausal women or men, where the LHRH agonist serves to medically induce suppression of ovarian/testicular steroid hormone production. Giredestrant antagonizes and degrades estrogen receptors, blocking estrogen-driven cancer cell proliferation. Palbociclib inhibits CDK4/6, blocking progression through the cell cycle, thus further suppressing cancer growth. The LHRH agonist reduces endogenous estrogen (and testosterone) production by downregulating pituitary gonadotropin signaling. The combination is intended to maximize endocrine blockade and cell cycle arrest in hormone receptor-dependent breast cancers[4][7][9].