Treatment of Metastatic Castration-resistant Prostate Cancer With Abiraterone and Enzalutamide Despite PSA Progression

BACKGROUND/AIM: National guidelines offer little guidance on the use of PSA progression (PSA increase as defined below) as a clinical endpoint in metastatic castration-resistant prostate cancer (mCRPC). The aim of the study was to examine treatment patterns/outcomes with abiraterone (abi)/enzalutamide (enza) throughout PSA progression and near the end of life (EOL). PATIENTS AND METHODS: Cases of mCRPC treated with abi or enza from the New York Veterans Affairs (VA) from 6/2011-8/2017 were reviewed. Regression analyses were conducted to identify factors associated with continuation of abi/enza treatment up to the EOL, and survival. RESULTS: Of 184 patients, 72 received abi alone, 28 received enza alone, and 84 received both. Treatment was changed for PSA progression alone in 39.1% (abi) and 25.7% (enza) of patients. A total of 37 patients (20%) received abi/enza within 1 month before death, 30% of whom were receiving hospice services. Older patients and black patients were less likely to receive abi/enza up to the EOL. CONCLUSION: Abi/enza are frequently discontinued for PSA progression alone and continued at EOL. The clinical benefit of these practices warrants additional study.