ORLANDO, FL, USA (UroToday.com) - Despite castrate levels of circulating androgens, stimulation of the androgen receptor is a critical pathway for castration-resistant prostate cancer (CRPC). Abiraterone acetate (AA), which irreversibly inhibits the enzyme CYP17, is a potent antiandrogen. Dr. Reid et al. investigated the effect of AA in 47 patients with CRPC who failed androgen deprivation therapy and had previously been treated with docetaxel.
AA was administered orally at a dose of 1000 mg daily in 28 day cycles. The median age, baseline serum PSA, prior number of hormonal therapies and prior chemotherapy agents was 67 years (range: 48-87), 403 ng/ml (range: 9.9-10,325), 3 (range: 1-4) and 1 (range: 1-4) respectively. 57% of patients had an ECOG performance status of 1 and 9% had a performance status of 2. Total maximal PSA declines with AA at any point on study of >30%, >50%, and >90% were observed in 69%, 51% and 15% of patients respectively. 23% of patients had improvement in their ECOG performance status and 53% maintained their performance status. Median duration of treatment was 167 days and 17 patients received >6 cycles of AA.
AA demonstrated anti-tumor activity in patients previously treated with docetaxel in this Phase II clinical trial as evidenced by declines in serum PSA and improvement in performance status. A Phase III trial is currently underway for patients with CRPC who have failed docetaxel.
Presented by A. H. Reid, MD, et al. at the 45th Annual Meeting of the American Society of Clinical Oncology (ASCO) - May 29 - June 2, 2009 - Orange County Convention Center, Orlando, Florida USA.
Written by UroToday.com Contributing Medical Editor Thomas J. Guzzo, MD, MPH, James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions.
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