ESSA Pharma Inc is a pharmaceutical company. The company was focused on the development of small-molecule drugs for the treatment of castration-resistant prostate cancer. It was developing drugs that selectively block the amino-terminal domain of the androgen receptor, potentially overcoming the known AR-dependent resistance mechanisms of CRPC and providing CRPC patients with the potential for increased progression-free and overall survival. Currently, the company has terminated its clinical trials and other studies.