Efficacy and Safety of Abiraterone Acetate in Elderly (≥75 Years) Chemotherapy-Naïve Patients with Metastatic Castration-Resistant Prostate Cancer.

Metastatic castration resistant prostate cancer primarily affects elderly men. In this post hoc analysis we investigated the safety andefficacy of abiraterone acetate in elderly (age 75 years or greater) and younger (less than 75 years) patient subgroups at the prespecified interim analysis (55% of total overall survival events) for the COU-AA-302 (Abiraterone Acetate in Asymptomatic or Mildly Symptomatic Patients with Metastatic Castration-Resistant Prostate Cancer) trial.

MATERIALS AND METHODS: Patients were stratified and randomized 1:1 to abiraterone acetate 1,000 mg plus prednisone/prednisolone 5 mg bid (abiraterone-prednisone) vs placebo plus prednisone/prednisolone 5 mg bid (prednisone alone) Co-primary end points were radiographic progression-free survival (rPFS) and OS Median time to event and hazard ratio (HR) were estimated using Kaplan-Meier method and Cox model, respectively

RESULTS: A total of 350 elderly patients treated with abiraterone-prednisone had significant improvements in overall and radiographic progression-free survival vs those with prednisone alone (HR 0.71, 95% CI 0.53-0.96 vs HR 0.63, 95% CI 0.48-0.83), similar to 738 younger patients (HR 0.81, 95% CI 0.63-1.03 vs HR 0.49, 95% CI 0.40-0.59). All secondary end points favored the abiraterone-prednisone arm for both age subgroups. Specific adverse events with abiraterone-prednisone were similar between the age subgroups. Elderly patients in both treatment arms had higher rates of fluid retention and cardiac disorders than younger patients, although rates of dose reduction or treatment interruptions due to adverse events were low in both age subgroups.

CONCLUSIONS: Abiraterone acetate demonstrated clinical benefit and was well tolerated in elderly and younger men with chemotherapy naïve,metastatic castration resistant prostate cancer. Thus, findings support it as a treatment option for elderly patients who may not tolerate other therapies with greater toxicity.

The Journal of urology 2015 Jul 04 [Epub ahead of print]

Matthew R Smith, Dana E Rathkopf, Peter F A Mulders, Joan Carles, Hendrik Van Poppel, Jinhui Li, Thian Kheoh, Thomas W Griffin, Arturo Molina, Charles J Ryan

Department of Genitourinary Oncology, Massachusetts General Hospital Cancer Center, Boston, Massachusetts Electronic address: smith matthew@mgh harvard edu , Department of Oncology and Internal Medicine, Memorial Sloan Kettering Cancer Center, New York, New York , Department of Urology, Radboud University Medical Centre, Nijmegen, The Netherlands , Department of Oncology, Vall d'Hebron University Hospital, Barcelona, Spain , Department of Urology, University Hospitals of KU Leuven, Leuven, Belgium , Department of Biostatistics Oncology, Janssen Research & Development, Raritan, New Jersey , Department of Biostatistics & Programming, Janssen Research & Development, San Diego , Department of WC Clinical Oncology , Department of Oncology, Janssen Research & Development, Los Angeles , Helen Diller Family Comprehensive Cancer Center, University of California San Francisco (CJR), San Francisco, California

Video Lecture presentation Journal Club: Abiraterone in Elderly mCRPC patients - Presenter Charles J. Ryan, MD.