Interim analysis of a randomised phase III study of abiraterone acetate in chemotherapy-naive patients with metastatic castration resistant prostate cancer
The first study to show activity of abiraterone acetate in chemotherapy-naive setting
- Date : 27 Jun 2012
- Topic : Genitourinary cancers
In patients with asymptomatic or mildly symptomatic chemotherapy-naive metastatic castration resistant prostate cancer, abiraterone acetate plus prednisone produced a statistically significant benefit in radiographic progression-free survival over placebo plus prednisone, according to a planned interim analysis of the randomised, phase III, multicenter, COUAA-302 study. The results were presented by Dr Charles Ryan of the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, USA at the 48th Annual Meeting of the American Society of Clinical Oncology (ASCO) in Chicago (1 - 5 June 2012).
With 43% of total events reported in the COUAA-302 study, the independent data monitoring committee concluded that the co-primary endpoints of overall survival and radiographic progression-free survival and secondary endpoints all favoured the abiraterone acetate arm and unanimously recommended unblinding the study and crossing patients over from placebo to abiraterone acetate treatment.
Clinically meaningful improvements
The natural history of progressive metastatic castration resistant prostate cancer can be prolonged, and can appear over a period of years. Therefore, several hallmarks of disease progression (time to opiate use as a surrogate for cancer-related pain, time to initiation of chemotherapy, time to Eastern Cooperative Oncology Group performance status deterioration, time to PSA progression) were used as secondary endpoints, to provide a comprehensive assessment of the magnitude of the clinical benefit conferred by abiraterone acetate. Therapy with abiraterone acetate delayed, to a clinically significant degree, the onset of these meaningful events.
The co-primary endpoint included progressive disease as determined by bone scan with blinded review by a central radiologist, progressive disease as determined by soft tissue lesions seen on computed tomography or magnetic resonance imaging, or death from any cause. Despite longer treatment with abiraterone acetate than in the prior study in patients with previous chemotherapy, no new safety signals were seen in the trial.
Abiraterone acetate plus prednisone previously demonstrated a benefit in overall survival over a prednisone control in patients with previous chemotherapy exposure, and these results were used to support the regulatory approval of the drug. In COUAA-302 study, abiraterone acetate plus prednisone delayed disease progression, increased survival, and extended time with minimal or no symptoms. It is the first study to show activity of abiraterone acetate in chemotherapy-naive patients, and the study data merit consideration as providing a new standard approach in this highly prevalent patient population faced with an unmet medical needs
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