The duration of prior hormonal treatment can predict responses to subsequent therapy in patients with metastatic castration-resistant prostate cancer (mCRPC).
To determine if prior endocrine therapy duration is an indicator of abiraterone acetate (AA) sensitivity.
Post-hoc exploratory analysis of randomised phase 3 studies examining post-docetaxel (COU-AA-301) or chemotherapy-naïve mCRPC (COU-AA-302) patients receiving AA. The treatment effect on overall survival (OS), radiographic progression-free survival (rPFS), and prostate-specific antigen (PSA) response analysed by quartile duration of prior gonadotropin-releasing hormone agonists (GnRHa) or androgen receptor (AR) antagonist.
Patients were randomised to AA (1000mg, orally once daily) plus prednisone (5mg, orally twice daily) or placebo plus prednisone. Prior endocrine therapy was GnRHa (COU-AA-301, n=1127 [94%]; COU-AA-302, n=1057 [97%], 45. 1 mo or 36. 7 mo median duration, respectively) and/or orchiectomy (COU-AA-301, n=78 [7%] COU-AA-302, n=44 [4%]); castrated patients received prior AR antagonists (COU-AA-301, n=1015 [85%]; COU-AA-302, n=1078 [99%], 15. 7 mo or 16. 1 mo median duration, respectively).
Cox model was used to obtain hazard ratio and associated 95% confidence interval with statistical inference by log rank statistic.
Clinical benefit with AA was observed for OS, rPFS, and PSA response for nearly all quartiles with GnRHa or AR antagonists in both COU-AA-301 and COU-AA-302. In COU-AA-301, patients with a longer duration of prior endocrine therapy tended to have greater AA OS, rPFS, and PSA response benefit, with lead-time chemotherapy bias potentially impacting COU-AA-301 results. Time to castration resistance was not captured. This analysis is limited as a post-hoc exploratory analysis.
In the COU-AA-301 and COU-AA-302 studies, AA produced clinical benefits regardless of prior endocrine therapy duration in patients with mCRPC.
Metastatic castration-resistant prostate cancer patients derived clinical benefits with abiraterone acetate regardless of prior endocrine therapy duration.
European urology. 2015 Oct 24 [Epub ahead of print]
Joaquim Bellmunt, Thian Kheoh, Margaret K Yu, Matthew R Smith, Eric J Small, Peter F A Mulders, Karim Fizazi, Dana E Rathkopf, Fred Saad, Howard I Scher, Mary-Ellen Taplin, Ian D Davis, Dirk Schrijvers, Andrew Protheroe, Arturo Molina, Peter De Porre, Thomas W Griffin, Johann S de Bono, Charles J Ryan, Stéphane Oudard
Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA. Janssen Research & Development, San Diego, CA, USA. , Janssen Research & Development, Los Angeles, CA, USA. , Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. , Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA. , Radboud University Medical Centre, Nijmegen, The Netherlands. , Institut Gustave Roussy, University of Paris Sud, Villejuif, France. , Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, NY, USA. , University of Montréal, Montréal, Québec, Canada. , Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, NY, USA. , Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA. , Monash University and Eastern Health, Victoria, Australia. , ZNA Middelheim Oncology Clinic, Medical Oncology, Antwerp, Belgium. , Churchill Hospital, Oxford, UK. , Janssen Research & Development, Menlo Park, CA, USA. , Janssen Research & Development, Beerse, Belgium. , Janssen Research & Development, Los Angeles, CA, USA. , The Institute of Cancer Research and The Royal Marsden Hospital, Sutton, UK. , Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA. , Georges Pompidou Hospital, University René Descartes, Paris, France.