A formulation containing an androgen receptor (AR) antagonist with potential antineoplastic activity. AR antagonist ODM-201 binds to ARs in target tissues; subsequently, inhibiting androgen-induced receptor activation and facilitating the formation of inactive complexes that cannot translocate to the nucleus. This prevents binding to and transcription of AR-responsive genes that regulate prostate cancer cell proliferation. This ultimately leads to an inhibition of growth in AR-expressing prostate cancer cells.