A Study of Enzalutamide Versus Bicalutamide in Castrate Men With Metastatic Prostate Cancer

PFS was calculated as the time from randomization to the date of the first progression event detected. A progression event was defined as objective evidence of radiographic disease progression based on the assessments by investigators, skeletal-related event, initiation of new antineoplastic therapy or death by any cause, whichever occurred first. Radiographic disease progression was defined as either a progression in soft tissue on CT/MRI scan according to RECIST 1.1, and/or a progression in bone lesions on bone scan (≥ 2 new bone lesions) confirmed by the next bone scan. A skeletal-related event was defined as radiation therapy or surgery to bone, pathologic bone fracture, spinal cord compression or change in antineoplastic therapy to treat bone pain. The initiation of new antineoplastic therapy included any new therapy for the treatment of disease progression after the study drug administration started.

The PSA response by Week 13 was defined as the percentage change from Baseline to the smallest PSA value after Baseline (i.e., a decrease of 100% represents the largest possible decrease to a value below the lower limit of quantification) and on or before day 99 (i.e., upper boundary of the Week 13 visit window). For participants with no decrease in PSA post-baseline by Week 13, the PSA response by Week 13 was the smallest increase in PSA up to day 99. For participants with no post-baseline PSA values up to day 99, the PSA response by Week 13 was set to missing. PSA was analyzed at a central laboratory.

The best PSA response was defined as the percentage change from Baseline to the smallest PSA value after Baseline including PSA results from samples taken after the study drug was stopped. For participants with no decrease in PSA post-baseline, the best PSA response was the smallest increase in PSA. For participants with no post-baseline PSA values, the PSA response was set to missing. PSA was analyzed at a central laboratory.

Time to PSA progression was calculated as the time interval from the date of randomization to the date of first observation of PSA progression. PSA progression was defined as a ≥ 25% increase and an absolute increase of ≥ 2 ng/mL above the nadir (or above the baseline value for participants who did not have a decline in PSA post-baseline values), and confirmed by a second consecutive PSA assessment at least 3 weeks later. For participants with no documented PSA progression, the time to PSA progression was censored on the date the last PSA sample was taken.

Time to PSA ≤ 4 ng/mL was defined as the time interval from the date of randomization to the first date a decline in PSA to a result of 4 ng/mL or below was recorded. In participants without PSA results ≤ 4 ng/mL, the time to PSA ≤ 4 ng/mL was censored on the date of the last PSA sample taken. Participants with a PSA result ≤ 4 ng/mL at Baseline, participants with no Baseline PSA and participants with no post-baseline PSA results were censored on the date of randomization

The time to ≥ 30% PSA decline from Baseline was defined as the time interval from the date of randomization to the first date a PSA decline from Baseline of at least 30% was recorded. In participants without ≥ 30% PSA decline from Baseline, the time to ≥ 30% PSA decline from Baseline was censored on the date of the last PSA sample taken. Participants who had no Baseline PSA and participants with no post-baseline PSA results were censored on the date of randomization.

The time to ≥ 50% PSA decline from Baseline was defined as the time interval from the date of randomization to the first date a PSA decline from Baseline of at least 50% was recorded. In participants without ≥ 50% PSA decline from Baseline, the time to ≥ 50% PSA decline from Baseline was censored on the date of the last PSA sample taken. Participants who had no Baseline PSA and participants with no post-baseline PSA results were censored on the date of randomization.

The time to ≥ 90% PSA decline from Baseline was defined as the time interval from the date of randomization to the first date a PSA decline from Baseline of at least 90% was recorded. In participants without ≥ 90% PSA decline from Baseline, the time to ≥ 90% PSA decline from Baseline was censored on the date of the last PSA sample taken. Participants who had no Baseline PSA and participants with no post-baseline PSA results were censored on the date of randomization.

Radiographic PFS was calculated as the time interval from the date of randomization to the first date of radiographic disease progression. Radiographic disease progression was defined as either a progression in soft tissue on CT/MRI scan according to RECIST 1.1, and/or a progression in bone lesions (a minimum of 2 new bone lesions as compared to previous scan) on bone scan and confirmed by the next bone scan.

Response assessments were reported by ICR for target lesions in soft tissues and non-target lesions in soft tissues based on CT and/or MRI according to RECIST version 1.1. Objective response was defined as the number of participants achieving either a complete response (CR) or a partial response (PR) based on participant's best overall response assessed at the end of the treatment.

A serious adverse event was defined as any untoward medical occurrence that at any dose: ● Resulted in death ● Was life threatening ● Resulted in persistent or significant disability/incapacity ● Resulted in congenital anomaly or birth defect ● Required inpatient hospitalization or led to prolongation of hospitalization ● Other medically important events. Treatment-related indicates adverse events assessed by the Investigator as probably or possibly related to study treatment. Treatment emergent adverse events (TEAEs) were defined as adverse events (AEs) that started or worsened after starting administration of study drug through end of the study (i.e., the treatment-emergent period).