Efficacy of Novel Hormone Agents in the Treatment of Metastatic Castration-resistant Prostate Cancer: A Real-world Retrospective Study

Abstract

Background/Aim: Novel hormone agents (NHA) have become important tools for the treatment of advanced prostate cancer. Among them, abiraterone and enzalutamide are two major regimens in the treatment of metastatic castration-resistant prostate cancer (MCRPC). The aim of this study was to evaluate the efficacy of both drugs in patients who had disease progression after androgen deprivation therapy (ADT), using our real-world database. Patients and Methods: We retrospectively analyzed MCRPC patients who received abiraterone and enzalutamide between October 2010 and October 2021. The associations between baseline demographics and clinical outcomes were evaluated. ADT was defined as luteinizing hormone-releasing hormone (LHRH) agonists, antagonists, or orchiectomy. Results: Of the 324 included patients, the median age was 77 years. Amongst them, 81 patients received chemotherapy-naïve abiraterone, 141 received post-chemotherapy abiraterone, 64 patients received chemotherapy-naïve enzalutamide and 38 patients received post-chemotherapy enzalutamide. The median overall survival was 43.6 months among all NHA-treated MCRPC patients. Pre-MCRPC ADT duration >25.31 months and enzalutamide use were each associated with a decreased risk of death (HR=0.54, 95% CI=0.39-0.75, p<0.001, and HR=0.53, 95% CI=0.33-0.87, p=0.012, respectively), while high-volume disease was associated with an increased risk of death (HR=1.53, 95% CI=1.10-2.21, p=0.007). Upfront chemotherapy and pre-MCRPC ADT duration of >21.03 months were each associated with an increased prostate-specific antigen (PSA) response after NHA treatment (OR=3.18, 95% CI=1.33-7.63, p=0.010, and OR=2.72, 95% CI=1.63-4.54, p<0.001, respectively). Conclusion: Our real-world data revealed the effectiveness of using both abiraterone and enzalutamide in the treatment of MCRPC patients. Long pre-MCRPC ADT duration and enzalutamide use were both associated with a decreased risk of death regardless of four different treatment sequences. Upfront docetaxel and longer pre-MCRPC ADT duration were each associated with an increased NHA PSA response rate.