Antitumour activity of abiraterone and diethylstilboestrol when administered sequentially to men with castration-resistant prostate cancer

Background: Abiraterone is a standard treatment for men with castration-resistant prostate cancer (CRPC). We evaluated the antitumour activity of abiraterone following the synthetic oestrogen diethylstilboestrol (DES). Methods: Castration-resistant prostate cancer patients treated with abiraterone were identified. Demographics, response variables and survival data were recorded. Results: Two-hundred and seventy-four patients received abiraterone, 114 (41.6%) after DES. Pre-chemotherapy abiraterone resulted in ⩾50% PSA declines in 35/41 (85.4%) DES-naïve and 20/27 (74.1%) DES-treated patients. Post-docetaxel abiraterone resulted in ⩾50% PSA declines in 40/113 (35.4%) DES-naïve and 23/81 (28.4%) DES-treated patients. Time to PSA progression was similar regardless of prior DES. Conclusion: Abiraterone has important antitumour activity in men with CRPC even after DES exposure.