EM-800

EM-800 is an orally active, nonsteroidal antiestrogen that acts as a pure antagonist at both estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). It is a high-affinity ligand for ERα and serves as the prodrug of acolbifene (also known as EM-652), its active metabolite. Unlike selective estrogen receptor modulators such as tamoxifen, EM-800 lacks agonist activity in the mammary gland and endometrium. It has demonstrated anticancer activity by inhibiting the growth of breast cancer cells in preclinical models and has shown clinical efficacy in patients with tamoxifen-resistant breast cancer. In phase II studies involving postmenopausal women with advanced or metastatic breast cancer who had relapsed after tamoxifen therapy, EM-800 produced objective responses and was well tolerated without significant adverse events[1][3][5][7]. Its mechanism involves complete antagonism of both activation domains (AF-1 and AF-2) on ERα/ERβ transcriptional functions.

Other names

prodrug of acolbifeneprecursor of acolbifene