Is abiraterone acetate well tolerated and effective in the treatment of castration-resistant prostate cancer?

This Practice Point commentary discusses the findings of the first phase I trial to evaluate abiraterone acetate (an inhibitor of the androgen-regulating enzyme CYP17) in the treatment of castration-resistant prostate cancer. This open-label, dose-escalation study by Attard et al. showed that abiraterone was well tolerated but often induced a syndrome of secondary mineralocorticoid excess that improved with eplerenone (a mineralocorticoid receptor antagonist). Abiraterone is a potent suppressor of adrenal androgen synthesis, and produced lasting prostate-specific antigen responses in approximately half of the patients. A few patients had partial regression of distant metastases. Although promising, these results should be interpreted with caution owing to the small sample size and because the study was not primarily designed to examine drug efficacy. Multi-institutional, prospective trials should provide additional information on the tolerability and activity of this compound and further define the population most likely to benefit from this endocrine approach.