A synthetic GNRHR antagonist (IC50 = 3 nM in HEK293 cells expressing the human receptor); inhibits the growth of WPMY-1, WPE1-NA22, BPH-1, and LNCaP prostate cell lines via caspase activation and induction of apoptosis (10 μM); decreases plasma testosterone levels in rats to castrate levels for the first 49 days post treatment (2 mg/kg); decreases tumor volume of Dunning R3327H prostate tumor flank implants in rats (1 mg/kg per month),