“True” Antiandrogens : Selective Non-Ligand-Binding Pocket Disruptors of Androgen Receptor−Coactivator Interactions: Novel Tools for Prostate Cancer

Prostate cancer (PCa) therapy typically involves administration of “classical” antiandrogens, competitive inhibitors of androgen receptor (AR) ligands, dihydrotestosterone (DHT) and testosterone (tes), for the ligand-binding pocket (LBP) in the ligand-binding domain (LBD) of AR. Prolonged LBP-targeting leads to resistance, and alternative therapies are urgently required. We report the identification and characterization of a novel series of diarylhydrazides as selective disruptors of AR interaction with coactivators through application of structure and ligand-based virtual screening. Compounds demonstrate full (“true”) antagonism in AR with low micromolar potency, selectivity over estrogen receptors α and β and glucocorticoid receptor, and partial antagonism of the progesterone receptor. MDG506 (5) demonstrates low cellular toxicity in PCa models and dose responsive reduction of classical antiandrogen-induced prostate specific antigen expression. These data provide compelling evidence for such non-LBP intervention as an alternative approach or in combination with classical PCa therapy