An orally bioavailable androgen receptor (AR) antagonist, with potential antineoplastic activity. Upon oral administration, AR antagonist TRC253 specifically binds to both wild-type and certain mutant forms of AR, thereby preventing 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, inhibits the expression of genes that regulate prostate cancer cell proliferation, and may lead to an inhibition of growth of tumor cells in which AR is overexpressed and/or mutated. AR is often overexpressed and/or mutated in prostate cancers and plays a key role in proliferation, survival and chemoresistance of tumor cells.