Participants receive 5 mg of opevesostat twice daily (BID) via oral tablet plus dexamethasone 1.5 mg by oral tablets once daily (QD) and 0.1 mg fludrocortisone acetate by oral tablet QD until progression or discontinuation.

Participants receive 5 mg of opevesostat BID via oral tablet plus dexamethasone 1.5 mg by oral tablets QD and 0.1 mg fludrocortisone acetate by oral tablet QD, PLUS 300 mg of olaparib BID via oral tablet until progressive disease or discontinuation.

Participants receive 5 mg of opevesostat BID via oral tablet plus dexamethasone 1.5 mg by oral tablets QD and 0.1 mg fludrocortisone acetate by oral tablet QD, PLUS 75 mg/m^2 of docetaxel once every 3 weeks (Q3W) via IV infusion, plus prednisone per approved product label BID by oral tablets until progressive disease or discontinuation.

Participants receive 5 mg of opevesostat BID via oral tablet plus dexamethasone 1.5 mg by oral tablets QD and 0.1 mg fludrocortisone acetate by oral tablet QD, PLUS 20 mg/m^2 of cabazitaxel Q3W via IV infusion, plus prednisone per approved product label BID by oral tablets until progressive disease or discontinuation.

Oral Tablet

The following events, if considered drug related by the investigator, will be considered a DLT: Grade 4 nonhematologic toxicity (not laboratory value); Grade 4 hematologic toxicity lasting >7 days, except thrombocytopenia (Grade 4 thrombocytopenia of any duration, Grade 3 thrombocytopenia associated with clinically significant bleeding); Any nonhematologic adverse event (AE) >Grade 3 in severity should be considered a DLT (with exceptions); Any Grade 3 or Grade 4 nonhematologic laboratory value (if certain criteria are met); Febrile neutropenia Grade 3 or Grade 4; Prolonged delay (>2 weeks) in initiating treatment after the first 28 days due to study intervention-related toxicity; Missing >25% of study intervention doses as a result of drug-related AE(s) during the first 28 days; Grade 5 toxicity.

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.

The Prostate-specific Antigen (PSA) response rate is the percentage of participants who had PSA response defined as a reduction in the PSA level from baseline by ≥50%. The reduction in PSA level will be confirmed by an additional PSA evaluation performed ≥3 weeks from the original response per Prostate Cancer Working Group (PCWG) criteria.

The ORR is defined as the percentage of participants with complete response (CR: disappearance of all target lesions per Response Criteria in Solid Tumors version 1.1 (RECIST 1.1); and no evidence of disease (NED) on base scan per Prostate Cancer Working Group (PCWG) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions per RECIST 1.1; and non-progressive disease, non-evaluable [NE], or NED on bone scan or CR with non-progressive disease or NE bone scan per PCWG). ORR will be assessed by Blinded Independent Central Review (BICR).