Efficacy of Androgen Receptor-targeted Drugs After Prostate Cancer Recurrence With Bone Metastases: PROSTAT-BSI Sub-analysis.

Background/aim: This study aimed to evaluate the therapeutic benefit of novel androgen receptor-targeted agents (ARTAs) in castration-resistant prostate cancer (CRPC) with bone metastases in Japan.

Patients And Methods: In followup to our prospective observational study (PROSTAT-BSI) from 2012 to 2018 on metastatic hormone-sensitive prostate cancer (mHSPC) and metastatic CRPC (mCRPC) before docetaxel initiation, we conducted this sub-analysis to investigate the benefit of ARTAs after clinical recurrence on overall survival (OS) in the real-world clinical setting in Japan. In this study, we compared patients who were treated with ARTA with those who received only vintage hormone therapy including docetaxel after clinical recurrence.

Results: In the mHSPC group, 69 patients became mCRPC and were treated with or without ARTAs. No significant difference was observed in prostate-specific antigen (PSA) progression-free survival between the ARTA (+) and ARTA (-) groups; however, OS after clinical recurrence was significantly better in the ARTA (+) group than in the ARTA (-) group (median OS 31.9 vs. 23.0 months; p<0.01).

Conclusion: The ARTAs are beneficial even after mHSPC recurrence in Japanese patients in the real-world clinical setting. Since ARTAs are beneficial after clinical recurrence, it may be better to switch to ARTAs whenever necessary based on PSA response after combined androgen blockade therapy, considering the adverse effects and cost. This approach may be suitable to reduce overtreatment in Japanese patients with mHSPC.