17β-Hydroxy exemestane

17β-Hydroxy exemestane (17-H-EXE) is the primary active metabolite of Exemestane (HY-13632). 17β-Hydroxy exemestane is an aromatase inhibitor (IC50 = 69 nM) and an androgen receptor (AR) agonist (IC50 = 39.6 nM) that is selective for AR over estrogen receptor α (ERα; IC50 = 21.2 μM). 17β-Hydroxy exemestane stimulates growth of AR- and ERα-positive MCF-7 (EC50= 2.7 μM) and T47D breast cancer cells (EC50s = 0.43 and 1500 nM for AR- and ER-mediated growth, respectively) and inhibits proliferation of testosterone-treated aromatase-overexpressing MCF-7 cells. 17β-Hydroxy exemestane inhibits increases in serum cholesterol and LDL levels and prevents decreases in bone mineral density in the lumbar vertebrae and femur, as well as femoral bending strength and compressive strength of the fifth lumbar vertebrae in ovariectomized rats[3][4][5].