Summary
Eligible participants will be randomly allocated to either the Experimental Arm or the Active Comparator Arm. In the Experimental Arm, participants will start taking abiraterone or enzalutamide (AA/ENZ) daily. Each participant's prostate-specific antigen (PSA) levels will be tested monthly and once PSA has dropped to >50% they will stop treatment. The treatment will remain paused until PSA levels have risen again above the pre-treatment baseline. Once PSA levels decline >50% again, treatment will again be paused. This cycle will continue until criteria for treatment failure have been met. In the Active Comparator Arm, participants will receive standard continuous treatment with abiraterone or enzalutamide (AA/ENZ) daily until criteria for treatment failure are met.