ESSA Pharma was a clinical-stage pharmaceutical company developing treatments for prostate cancer, with no approved products or commercial revenue. Its lead asset was masofaniten (EPI-7386), a small molecule designed to inhibit the N-terminal domain (NTD) of the androgen receptor (AR) — the protein that drives prostate cancer growth. Existing approved drugs target the ligand-binding domain (LBD) of the AR, and ESSA's thesis was that blocking the NTD could bypass resistance mechanisms that cause those drugs to eventually fail. The intended use case was metastatic castration-resistant prostate cancer (mCRPC), a late-stage form of the disease that no longer responds to standard hormone therapy. ESSA's business model was entirely contingent on advancing masofaniten through clinical development and eventually commercializing or licensing the drug to a larger pharmaceutical company. In October 2024, ESSA terminated all clinical trials after a Phase 2 interim review showed no meaningful efficacy benefit for masofaniten plus enzalutamide over enzalutamide alone in mCRPC patients. All other studies, including combinations with abiraterone and darolutamide in partnership with Janssen and Bayer, were also terminated. ESSA has since withdrawn its regulatory filings, terminated its university license agreement, and is conducting a strategic review of options including a merger, asset sale, shareholder distribution, or wind-down. The company has no remaining assets in active development and no path to revenue.