OS was defined as the time from the date of randomization until the date of death. For participants without documentation of death, OS was censored at the last date the participant was known to be alive.

All randomized participants

Progression-free survival, as determined by the investigator, was defined as the time from randomization to the earliest date of confirmed Prostate-Specific Antigen (PSA) progression, confirmed radiological progression, clinical deterioration, or death.

All randomized participants

For participants who discontinued treatment or experienced disease progression while on study therapy and then received subsequent non-hormonal cytotoxic therapy, time to subsequent non-hormonal cytotoxic therapy was defined as the time from randomization to the time of initiation of subsequent non-hormonal cytotoxic therapy. Participants who did not receive subsequent non-hormonal cytotoxic therapy were censored on the last known alive date (for participants who have not died) or the date of last follow-up contact at which the participants was known alive (for participants who died).

All randomized participants who received subsequent non-hormonal cytotoxic therapy

Time to pain progression was defined as the time from randomization to the time of the earliest date of any of the following 4 events: 1) an increase in average daily worst pain intensity of >= 2 points from baseline according to the Brief Pain Inventory - Short Form (BPI-SF), maintained over 2 consecutive time periods. 2) initiation of opioid analgesic (excluding codeine or dextropropoxyphene). 3) initiation of palliative radiotherapy for prostate cancer. 4) increase in mean Analgesic Score (AS) of >= 25% from baseline (for participants with baseline AS > 10) or increase in mean AS >= 10 points from baseline (for participants with baseline AS <= 10).

Participants who did not experience any of these events were censored on the earliest date among the latest BPI-SF completion date with non-missing worst pain assessment and last evaluable disease assessment date as defined in the PFS censoring mechanism.

All randomized participants

AE=any new unfavorable symptom, sign, or disease or worsening of a preexisting condition that may not have a causal relationship with treatment. SAE=a medical event that at any dose results in death, persistent or significant disability/incapacity, or drug dependency/abuse; is life-threatening, an important medical event, or a congenital anomaly/birth defect; or requires or prolongs hospitalization. irAE=AEs consistent with an immune mediated mechanism. imAR=AEs of special interest that were adjudicated as imAR by investigator. Treatment-related=having certain, probable, possible, or missing relationship to study drug. Grade (Gr) 1=Mild, Gr 2=Moderate, Gr 3=Severe, Gr 4= Potentially Life-threatening or disabling. Events were graded using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 3.0.

All treated participants

NCI CTC, Version 3 used to assess parameters. LLN=lower limit of normal. ULN=upper limit of normal. CTC criteria:

White blood cells (WBC): Gr 3:<2.0 to 1.0*10^9/L, Gr 4:<1.0*10^9/L. Absolute neutrophil count (ANC): Gr 3:<1.0 to 0.5*10^9/L, Gr 4:<0.5*10^9/L.

Platelet count: Gr 3:<50.0 to 25.0*10^9/L, Gr 4:<25.0 to 10^9/L. Hemoglobin: Gr 3:<8.0 to 6.5 g/dL, Gr 4:<6.5 g/dL. Absolute Lymphocyte Count (ALC): Gr 3: 0.2 - <0.5*10^9/L, Gr 4: <0.2*10^9/L.

Lipase: Gr 3:> 2.0 - 5.0 * ULN; Gr 4: > 5.0 X ULN. Amylase: Gr 3: > 2.0 - 5.0 * ULN; Gr 4: > 5.0 * ULN. Alanine Aminotransferase (ALT) Gr 3: > 5.0 - 20.0 * ULN; Gr 4: > 20.0 * ULN. Aspartate Aminotransferase (AST): Gr 3: > 5.0 - 20.0 * ULN; Gr 4: > 20.0 * ULN. Bilirubin: Gr 3: > 3.0 - 10.0 * ULN; Gr 4: > 10.0 * ULN. Alkaline Phosphatase: Gr 3: > 5.0 - 20.0 * ULN; Gr 4: > 20.0 * ULN. Creatinine: Gr 3: > 3.0-6.0 * ULN, Gr 4: >6.0 * ULN.

All treated participants with on-study laboratory results