Abiraterone acetate (INN, USAN, BAN, JAN) (brand names Zytiga, Abiratas, Abretone, Abirapro) is a steroidal antiandrogen, specifically an androgen synthesis inhibitor, used in combination with prednisone in metastatic castration-resistant prostate cancer (previously called hormone-resistant or hormone-refractory prostate cancer) – i.