MDV3100 (Enzalutamide) is an orally-available thioxoimidazoline androgen receptor antagonist approved in August, 2012, for the treatment of castration-resistant prostate cancer (CRPC). In LNCaP/AR cells, MDV3100 has a potency of 36 nM. [1] MDV3100 blocks testosterone binding to AR and has approximately 5-fold higher binding affinity for AR than bicalutamide. In contrast to bicalutamide, MDV3100 does not promote translocation of AR to the nucleus and also prevents AR binding to DNA and other coactivator proteins. In contrast to bicalutamide in LNCaP cell lines, MDV3100 downregulates expression of PSA and TMPRSS2 genes and is an antagonist of the W741C mutant androgen receptor.

Early preclinical studies also indicate that MDV3100 may be a potential treatment for breast cancer; enrollment for Phase I trials are underway.