abemaciclib + leuprorelin + tamoxifen

This is a combination regimen consisting of three agents used in the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced or metastatic breast cancer. - **Abemaciclib** is a selective cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor that blocks cell cycle progression, thereby inhibiting proliferation of cancer cells. - **Leuprorelin** (also known as leuprolide) is a luteinising hormone-releasing hormone (LHRH) agonist that suppresses ovarian function and reduces estrogen production, effectively inducing medical menopause in premenopausal women. - **Tamoxifen** is a selective estrogen receptor modulator (SERM) that competitively inhibits estrogen binding to its receptor on breast cancer cells, blocking the proliferative action of estrogen. This combination targets multiple pathways involved in the growth and survival of HR+ breast cancer cells—abemaciclib directly inhibits cell cycle progression; leuprorelin suppresses endogenous estrogen production; tamoxifen blocks residual estrogen activity at the tumor site. This regimen may be used particularly for premenopausal women with HR+/HER2- advanced or metastatic breast cancer[2][3][4].