In vitro activity: In AR-HEK293 cells stably expressing full-length hAR, ODM-201 inhibits human AR (hAR) with IC50 of 26 nM. ODM-201 inhibits VCaP cell proliferation with IC50 of 230 nM, while has no effect on the viability of AR-negative cell lines tested, DU-145 prostate cancer cells and H1581 lung cancer cells.

Kinase Assay: AR binding affinities of test compounds are studied in cytosolic lysates obtained from ventral prostates of castrated rats by a competition binding assay. Fresh prostates are minced and homogenized with Buffer A containing protease inhibitors. The homogenates are centrifuged and the resultant supernatants are treated with a dextran-coated charcoal solution to remove endogenous steroids. The dissociation constant of the radio ligand [3H]mibolerone for isolated rat ARs is determined in a saturation binding experiment. For the determination of Ki values, prostate cytosol preparations and 1 nM [3H]mibolerone are incubated with increasing concentrations of test compounds overnight. After the incubation, bound and free steroids are separated by treatment with 100 μL of dextran-coated charcoal suspension. Bound radioactivity is determined by counting 100 μL of supernatant fraction in 200 μL of scintillation fluid using a microbeta counter. All procedures are carried out at 0–4 °C.

Cell Assay: VCaP cells are treated with a submaximal concentration of mibolerone (0.1 nM) and increasing concentrations of test compounds in steroid-free assay medium supplemented with 4 mM GlutaMAX. After a 4-day incubation with the compounds, cell viability is measured using a WST-1 cell proliferation assay. To rule out non-AR –mediated toxicity, AR-negative PC cells (DU-145) and lung cancer cells (H1581) are treated with an increasing concentration of ODM-201, and cell viability is measured as described above.