Adaptive Abiraterone Therapy for Metastatic Castration Resistant Prostate Cancer

In this pilot study, 10 black participants and 15 non-black participants will be enrolled after achieving 50% or more decline of their prostatic specific antigen (PSA) while on abiraterone for asymptomatic or minimally symptomatic metastatic castration resistant prostate cancer (mCRPC). Abiraterone will be stopped and will not be re-initiated until there is 50% or more increase of the PSA. Each time abiraterone is stopped, it will be defined as the start of a new adaptive therapy cycle. Participants who cannot achieve a 50% decline of their PSA after restarting abiraterone will continue abiraterone until they develop radiographic disease progression. If the decline in performance status does not occur at the time of radiographic disease progression, participants will be followed until they develop radiographic disease progression. The study will be terminated early if less than 3 of the first 10 enrolled participants can complete 2 cycles of the adaptive abiraterone.