Inclusion criteria:

          -  Diagnosis of prostate adenocarcinoma

          -  Must have appropriate deleterious homologous recombination repair (HRR) gene
             alteration

          -  Metastatic disease as documented by at least one bone lesion

          -  Androgen deprivation therapy (either medical or surgical castration) must have been
             started >=14 days prior to randomization and willing to continue through the treatment
             phase.

          -  Other allowed prior therapy for metastatic castration-sensitive prostate cancer
             (mCSPC): (a) maximum of 1 course of radiation or surgical intervention to manage
             symptoms of prostate cancer. Radiation with curative intent is not allowed. Radiation
             must be completed prior to randomization (b) <= 6 months of androgen deprivation
             therapy (ADT) prior to randomization; and (c) 30 days of abiraterone acetate +
             prednisone (AA-P) allowed if required

        Exclusion criteria:

          -  Prior treatment with a poly (adenosine diphosphate-ribose) polymerase (inhibitor)
             (PARP) inhibitor- History of adrenal dysfunction

          -  Long-term use of systemically administered corticosteroids (greater than [>] 5
             milligrams [mg] of prednisone or the equivalent) during the study is not allowed.
             Short-term use (<=4 weeks, including taper) and locally administered steroids (for
             example, inhaled, topical, ophthalmic, and intra-articular) are allowed, if clinically
             indicated

          -  History or current diagnosis of myelodysplastic syndrome (MDS)/ acute myeloid leukemia
             (AML)