The study for each participant consists of a Screening period (28 days), a treatment period, a post-treatment safety follow-up (30 days) followed by a long-term follow-up period.
During the treatment period:
* JSB462 is administered from randomization, orally, daily and continuously (100 mg or 300 mg QD) until disease progression per PCWG3-modified RECIST 1.1 as assessed by the investigator, the occurrence of unacceptable toxicities, death, participant decision or investigator decision.
* Abiraterone 1000 mg or enzalutamide 160 mg are administered from randomization, orally, daily, and continuously until disease progression per PCWG3-modified RECIST 1.1 as assessed by the investigator, the occurrence of unacceptable toxicities, death, participant decision or investigator decision.
During the post-treatment follow up period:
* Safety follow-Up: After discontinuation of study treatment, all participants will be followed for at least 1 safety follow-up visit (30 days \[+/- 7 days\] after treatment discontinuation). Subsequent lines of therapy may be administered according to investigator's discretion after treatment discontinuation.
* Long-term follow-up: Starts after the Safety follow-up period and lasts until the end of study. Safety, efficacy and survival information may be collected from participants during this period.
