A Study of Niraparib Combination Therapies for the Treatment of Metastatic Castration-Resistant Prostate Cancer

Inclusion Criteria for Combination 3: * Diagnosed with mCRPC, who in the opinion of the investigator may benefit from treatment in Combination 3 of this study * Able to continue gonadotropin releasing hormone analogue (GnRHa) therapy during the study if not surgically castrate (that is, subjects who has not undergone bilateral orchiectomy). * Eastern Cooperative Oncology Group Performance Status (ECOG PS) of less than or equal to (\<=) 1 * Toxicity associated with prior chemotherapy or radiotherapy has resolved to Grade \<= 1 (except alopecia or Grade \<= 2 neuropathy) at screening * Participant must agree not to donate sperm while on study treatment, and for 3 months following the last dose of study treatment Exclusion Criteria: * History or current diagnosis of myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) * Active malignancies (that is, progressing or requiring treatment change in the last 24 months) other than the disease being treated under study. The only allowed exceptions are: non-muscle invasive bladder cancer; skin cancer (non-melanoma or melanoma); breast cancer; malignancy that is considered cured with minimal risk of recurrence * Active infection requiring systemic therapy * Allergies, hypersensitivity, or intolerance to niraparib or the corresponding excipients Combination 3: * Symptomatic brain metastases * Prior disease progression during combination treatment with AA and poly (adenosine diphosphate \[ADP\]-ribose) polymerase inhibitor (PARP…