SU086 is an inhibitor of HSP90, binds to HSP90-alpha and HSP90-beta isoforms, decreases HSP90 protein levels in prostate cancer cells.SU086 is a potent inhibitor of prostate cancer cell growth, migration, and invasion in vitro, significantly inhibited growth of AR-positive CRPC cell lines (C4-2), AR-negative (DU145 and PC-3) CRPC cells, and CRPC cells with expression of AR and AR splice variant, AR-V7 (22Rv1) (IC50 <10 uM).SU086 inhibits prostate cancer growth in preclinical models of prostate cancer in vivo.SU086 strongly enhances the anti-tumor activity of standard of care second-generation anti-androgens enzalutamide and abiraterone and inhibits prostate cancer cell growth in vitro and tumor growth in vivo.