Galeterone (also known as TOK-001) is a synthetic steroidal compound investigated as a potential treatment for prostate cancer, particularly castration-resistant prostate cancer (CRPC). It acts as a multi-target agent by inhibiting CYP17A1 (reducing androgen biosynthesis) and functioning as an androgen receptor antagonist, thereby disrupting androgen receptor signaling essential for prostate cancer cell growth and survival. This leads to reduced cancer cell proliferation and induction of apoptosis. Galeterone was developed for patients resistant to standard androgen deprivation therapies. However, following disappointing results in phase III clinical trials (e.g., ARMOR3-JP), its development was discontinued in 2017 by Tokai Pharmaceuticals. It remains a specialty chemical of interest in pharmaceutical research.