What Predicts Minimal Response to Abiraterone in Metastatic Castrate-resistant Prostate Cancer?

Background: Several treatments have been shown to prolong survival in metastatic castrate-resistant prostate cancer (mCRPC); the optimum sequencing of these is not established. We investigated methods of identifying patients with mCRPC unlikely to respond to abiraterone. Patients and Methods: A retrospective analysis was carried-out in 47 consecutive patients with mCRPC treated sequentially with androgen deprivation (LHRH alpha), bicalutamide, docetaxel then abiraterone. Results: The median progression-free survival in patients treated with abiraterone was shorter in those with <= 18 months' response to LHRH alpha (118 vs. 279 days; p=0.018), bicalutamide non-responders (91 vs. 196 days; p=0.003) and patients with <= 6 months' response to docetaxel (102 vs. 294 days; p<0.001). The median overall survival was also shorter (348 vs. 815 days, p=0.016; 413 vs. 752 days, p=0.009; and 325 vs. 727 days, p<0.04, respectively). Conclusion: A response of <= 18 months' to LHRH alpha, non-response to bicalutamide and <= 6 months' response to docetaxel predicted poor response to abiraterone.