Early PSA response to antiandrogen therapy in metastatic castration-resistant prostate carcinoma patients: A predictive marker for progression-free survival?

Purpose: Enzalutamide and abiraterone acetate (AA) are the main therapeutic approaches for the treatment of metastatic castration-resistant prostate cancer (mCRPC) after the failure of androgen deprivation therapy during or following docetaxel-based chemotherapy. The aim of the present study was to investigate the role of early prostate-specific antigen (PSA) decline (four weeks after anti-androgen therapy) in predicting long-term progression free survival (PFS). Methods: In this retrospective study, we evaluated 65 patients who had histologically confirmed metastatic prostate cancer and were treated with AA or enzalutamide in the post-docetaxel period. Serum PSA levels were evaluated at 4th and then 12th week The main goal of this study was to demonstrate that an early PSA decline predicts PFS. Results: Between May 2015 and June 2019, the medical records of 65 patients were collected. Of these patients, 38 (58.5%) received AA and 27 (41.5%) enzalutamide. Early PSA response rate (RR; >= 30% and >= 50% from baseline at the 4th week) was identified in 38.5% (n=25) and 15.3% (n=10) of the patients, respectively. In multivariate analysis, we found that PSA RR >= 30% in patients had a statistically significant advantage in terms of PFS (HR: 0.38, 95% CI (0.13-0.71;p =0.03). Conclusion: In conclusion, 30% PSA RR was significantly associated with a better PFS.