SAN FRANCISCO, CA (UroToday.com) - Dr. Danila, spoke about abiraterone acetate (AA), an oral and irreversible inhibitor of CYP17 that decreases testosterone and DHT levels to undetectable. The study presented sought to determine the proportion of patients achieving a PSA decline of >50% and to assess toxicity. It was a multicenter trial using AA 1000mg orally daily and prednisone 5mg daily. Successful AA activity was defined as a PSA decline >50% in >30% of patients. It was not successful if the PSA decline occurs in <10% of patients.
44% met the criteria of >50% PSA decline. Radiological assessment was possible in 26 men who had at least 3 cycles of treatment. No decreases in bone metastasis by bone scans were noted, but some had unchanged bone scans. The addition of prednisone reduced the frequency of adverse events. Circulating tumor cells (CTCs) was used as an additional means to asses response to treatment and did correlate with PSA changes. A total of >5 CTCs prior to treatment that decreased to <3 CTCs correlated with response. To date, 13 of 38 patients continue on therapy. A phase III trial is planned to compare AA and prednisone to placebo and prednisone.
Presented by D.C. Danila at the 2008 Genitourinary Cancers Symposium - A Multidisciplinary Approach - February 14-16, 2008 San Francisco, California, USA
American Society of Clinical Oncology (ASCO)
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