AUTHOR=Raju Rachel , Sahu Arvind , Klevansky Myron , Torres Javier 

TITLE=Real-World Data on Outcomes in Metastatic Castrate-Resistant Prostate Cancer Patients Treated With Abiraterone or Enzalutamide: A Regional Experience

JOURNAL=Frontiers in Oncology

VOLUME=Volume 11 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.656146

DOI=10.3389/fonc.2021.656146

ISSN=2234-943X

ABSTRACT=Background
Both abiraterone and enzalutamide have shown to improve overall survival (OS), progression-free survival (PFS) and prostate-specific antigen (PSA) response in patients with metastatic castration-resistant prostate cancer (mCRPC) regardless of previous treatment with chemotherapy (COU-AA3011, COU-AA3022, AFFIRM3 and PREVAIL4). The data regarding the impact of these treatments in regional health services is scarce. This study assessed the survival outcomes in mCRPC patients in a regional health service in Victoria with the use of abiraterone and enzalutamide.  

Methods
This retrospective clinical audit included 75 patients with diagnosis of mCRPC treated with either abiraterone or enzalutamide between 1st of January 2014 to 31st of December 2019 at Goulburn Valley Health. Patients were stratified according to the drug received, Eastern Cooperative Oncology Group (ECOG) performance, Gleason score, burden of disease, presence of visceral metastases and use of previous chemotherapy. The primary end point was PSA response. The secondary outcomes were PSA PFS, radiographic PFS, and OS.

Results
Thirty seven patients received enzalutamide, and the other 38 received abiraterone. Only 20% of patients in either group had visceral metastases. 32% of patients receiving enzalutamide had a high burden of disease, compared to 53% receiving abiraterone. 38% of patients in the enzalutamide group and 53% in the abiraterone group had received prior chemotherapy. PSA response rates were higher in the enzalutamide group than abiraterone group (70.3% vs 37.8%). Both PSA and radiographic PFS were longer in the enzalutamide group than abiraterone group; 7 months vs 5 months for both end points. OS was also found to be longer in patients receiving enzalutamide; 30 months compared to only 13 months in patients receiving abiraterone.

Conclusion
Both abiraterone and enzalutamide have shown to result in significant PSA response rates, as well as PFS and OS benefit in mCRPC patients in the real world setting, as reflected in previous clinical trials. The difference in responses and survival benefit are probably impacted by the unbalanced burden of disease.