Study Comparing Orteronel Plus Prednisone in Participants With Metastatic Castration-Resistant Prostate Cancer.

rPFS was defined as the time from randomization until radiographic disease progression or death due to any cause, whichever occurred first. Radiographic disease progression was defined as the occurrence of 1 or more of the following: The appearance of 2 or more new lesions on radionuclide bone scan as defined by prostate cancer working group (PCWG)2; Should 2 or more new bone lesions be evident at the first assessment (8-week assessment) on treatment, 2 or more additional new lesions must have been evident on a confirmatory assessment at least 6 weeks later; One or more new soft tissue/visceral organ lesions identified by computed tomography (CT)/magnetic resonance imaging (MRI); Progression as defined by response evaluation criteria in solid tumors (RECIST) 1.1 criteria.

The PSA50 was defined as the percentage of participants who had a PSA decline of at least 50 percent (%) from baseline.

Pain response was defined as the occurrence of 1 of the following and confirmed by an additional assessment, at least 3 weeks but not more than 5 weeks later: A greater than or equal to (>=) 2 point reduction from baseline in BPI-SF worst pain score without an increase in analgesic use; or a 25 percent (%) or more reduction in analgesic use from baseline without an increase in worst pain score from baseline.

ECOG assessed participant's performance status on 5 point scale: 0=Fully active/able to carry on all pre-disease activities without restriction; 1=restricted in physically strenuous activity, ambulatory/able to carry out light or sedentary work; 2=ambulatory (>50% of waking hours [hrs]), capable of all self care, unable to carry out any work activities; 3=capable of only limited self care, confined to bed/chair >50% of waking hrs; 4=completely disabled, cannot carry on any self care, totally confined to bed/chair; 5=dead. Worst change was defined as the worst overall change that occurred in ECOG status at any measured time point during the treatment period.

The PSA50 was defined as the percentage of participants who had a PSA decline of at least 50% from baseline.

The PSA90 was defined as the percentage of participants who had a PSA decline of at least 90% from baseline.

The PSA90 was defined as the percentage of participants who had a PSA decline of at least 90% from baseline.

The PSA50 was defined as the percentage of participants who had a PSA decline of at least 50% from baseline. PSA90 was defined as the percentage of participants who had a PSA decline of at least 90% from baseline.

Time to PSA progression was defined as time from randomization to a PSA increase of 25% and PSA rise of at least 2 nanogram per milliliter (ng/mL) above the lowest value observed post baseline or, if no PSA decline occurred post baseline, above the baseline PSA.

A favorable CTC count was defined as less than (<) 5 counts per (/) 7.5 mililiter (mL) in whole blood. An unfavorable CTC count was defined as >=5 counts/7.5 mL in whole blood.

Percentage of participants with objective response based assessment of confirmed complete response (CR) or confirmed partial response (PR) according to RECIST 1.1. The overall objective response was defined as a complete response (CR) or partial response (PR). A complete response (CR) was defined as the disappearance of all target lesions determined by computerized tomography (CT) or MRI. Any pathological lymph nodes (whether target or non-target) must have had reduction in short axis to <10 millimetre (mm). A PR was defined as at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of longest diameters of non-lymph node lesions and of the short diameter(s) or short axis of lymph nodes.

Time to pain progression was defined as the time from participant randomization to the first assessment date of pain progression. Pain progression was defined as the occurrence of 1 of the following and confirmed by an additional assessment, at least 3 weeks but not more than 5 weeks later: The brief pain inventory-short form (BPI-SF) worst pain score was >= 4 with a >= 2 point increase over baseline in BPI-SF worst pain score with stable or increased analgesic use; The BPI-SF worst pain score was >= 4 but not less than baseline with new or increased (relative to baseline) Step II or Step III analgesic use; The BPI-SF worst pain score was <= 3 but not less than baseline with new or increased (relative to baseline) Step III analgesic use.

Time to pain response was defined as the time from randomization until first pain response. Pain response was defined as the occurrence of 1 of the following and confirmed by an additional assessment, at least 3 weeks but not more than 5 weeks later: A >= 2 point reduction from baseline in BPI-SF worst pain score without an increase in analgesic use, or a 25% or more reduction in analgesic use from baseline without an increase in worst pain score from baseline. The analysis was performed by Kaplan-Meier method.

Best pain response was evaluated in participants who had a pain response across the entire study were summarized by treatment group. The pain response was defined as a >=2-point reduction from baseline in BPI-SF worst pain score without an increase in analgesic use, or a 25% or more reduction in analgesic use from baseline without an increase in worst pain score from baseline.

The global health status or quality of life (QOL) was measured as the HRQOL response rate at 12 weeks using the 2-item global health status index of the european organization for research and treatment of cancer-quality of life questionnaire-C30 (EORTC QLQ-C30) instrument. HRQOL response was defined as a 17-point increase from the baseline assessment on the QOL index, after the score had been linearly transformed to a 0 to 100 scale. EORTC QLQ-C30: included 5 functional scales (physical, role, cognitive, emotional, and social), 1 global health status, 3 symptom scales (fatigue, pain, nausea/vomiting) and 6 single items (dyspnoea, appetite loss, insomnia, constipation/diarrhea and financial difficulties). Most questions used 4 point scale (1 'Not at all' to 4 'Very much'; 2 questions used 7-point scale (1 'very poor' to 7 'Excellent'). Scores averaged, transformed to 0-100 scale; higher score representing better level of functioning or greater degree of symptoms.