A Study of Enzalutamide Plus Androgen Deprivation Therapy (ADT) Versus Placebo Plus ADT in Patients With Metastatic Hormone Sensitive Prostate Cancer (mHSPC)

rPFS was calculated as the time from the date of randomization to the first objective evidence of radiographic progression disease (rPD) at any time or death up to 24 weeks after study drug discontinuation without documented radiographic progression, whichever occurred first. rPD was defined as progressive disease by Response Evaluation Criteria in Solid Tumors version 1.1 for soft tissue disease or by appearance of 2 or more new lesions on bone scan compared to baseline or week 13 according to PCWG2 criteria, as assessed by ICR or death. In participants with no rPFS event, rPFS was censored on the date of last evaluable radiographic assessment prior to the data analysis cutoff date. In participants with no baseline radiographic assessment, participants with no postbaseline radiographic assessments and participants with all postbaseline radiographic assessments documented as "not evaluable (NE)," rPFS was censored on the date of randomization.

rPFS was calculated as the time from the date of randomization to the first objective evidence of radiographic progression disease (rPD) at any time or death up to 24 weeks after study drug discontinuation without documented radiographic progression, whichever occurred first. rPD was defined as progressive disease by Response Evaluation Criteria in Solid Tumors version 1.1 for soft tissue disease or by appearance of 2 or more new lesions on bone scan compared to baseline for week 13 or the best response on treatment for week 25 or later assessments, as assessed by ICR or death. In participants with no rPFS event, rPFS was censored on the date of last evaluable radiographic assessment prior to the data analysis cutoff date. In participants with no baseline radiographic assessment, participants with no postbaseline radiographic assessments and participants with all postbaseline radiographic assessments documented as "not evaluable (NE)," rPFS was censored on the date of randomization.

OS was defined as the time from randomization to death due to any cause. In participants still alive at the date of the analysis cutoff point, OS was censored on the last date the participant was known to be alive. OS was analyzed using Kaplan-Meier estimates.

Time to PSA progression was calculated as the time from the date of randomization to the first observation of PSA progression. A PSA progression was defined as a ≥ 25% increase and an absolute increase of ≥ 2 ng/mL above the nadir, which was confirmed by a second consecutive value at least 3 weeks later. In participants with no PSA progression, time to PSA progression was censored on the date of the last PSA sample taken (or last value prior to 2 or more consecutive missed PSA assessments).

In participants with a new antineoplastic therapy initiated for prostate cancer after randomization, time to start of a new antineoplastic therapy was defined as the time interval from randomization to the date of the first dose administration of the first antineoplastic therapy. In participants with no new antineoplastic therapy initiated for prostate cancer after randomization, time to start of new antineoplastic therapy was censored on the last visit date or the date of randomization, whichever occurred last. Time to start of new antineoplastic therapy was analyzed using Kaplan-Meier estimates.

The PSA undetectable rate was defined as the percentage of participants with undetectable (< 0.2 ng/mL) PSA values at any time during study treatment, of those participants with detectable (≥ 0.2 ng/mL) PSA values at baseline.

The ORR was calculated as the percentage of participants who achieved a completed response (CR) or a partial response (PR) (unconfirmed responses) in their soft tissue disease using the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 assessed by ICR.

In participants with deterioration, the time to deterioration was calculated as the time interval between randomization and the first deterioration in urinary symptoms at any postbaseline visit. A deterioration in urinary symptoms was defined as an increase in the Quality of Life Prostate-specific Questionnaire (QLQ-PR25) modified urinary symptoms. Subscale score by ≥ 50% of the standard deviation observed in the QLQ-PR25 modified urinary symptoms subscale score at baseline. Modified urinary symptoms subscale score consisted of 3-items (Q31 - Q33) from the QLQ-PR25, each scored from 1 (not at all) to 4 (very much). The total modified urinary symptoms subscale score ranges from 0-100, with higher scores represents a higher level of symptomatology/problems. In participants without deterioration in urinary symptoms, the time to deterioration in urinary symptoms was censored on the date the last urinary symptoms QLQ-PR25 score was calculable.

Time to first SSE was calculated as the time from randomization to the occurrence of the first SSE. An SSE was defined as radiation to bone, surgery to bone, clinically apparent pathological bone fracture, or spinal cord compression. In participants with no SSE, time to SSE was censored on the last visit date or the date of randomization, whichever occurred last.

Time to castration resistance was calculated as the time from randomization to the first castration-resistant event. A castration resistance event was defined as any of the following in the presence of castrate levels of testosterone (< 50 ng/dL): radiographic disease progression, PSA progression or SSE, whichever occurred first. In participants with no documented castration resistance event, the time to castration resistance was censored on the latest date from: the date of last radiologic assessment, the last PSA sample taken prior to the start of any new prostate cancer therapy and prior to 2 or more consecutive missed PSA assessments (if applicable), and the last visit date performed.

Time to deterioration of QoL was calculated as the time interval from the date of randomization to the first date a decline from baseline of 10 points or more in the FACT-P total score was recorded. The FACT-P consists of 27 core items that assess participant function in 4 domains and 12 prostate cancer-related items grouped into 5 subscales as follows: physical wellbeing, social/family wellbeing, emotional wellbeing, functional wellbeing and prostate cancer subscale. Each item is rated on a 0 to 4 Likert-type scale. The FACT-P total score is the sum of all 5 subscale scores of the FACT-P questionnaire and ranges from 0 to 156), where high score represent better quality of life. In participants without FACT-P progression, the time to deterioration of QoL was censored on the date of the last FACT-P total score was calculable.

Time to pain progression was defined as time from randomization to the first pain progression event. Pain progression was defined as an increase of ≥ 30% from baseline in the average BPI-SF pain severity score. BPI-SF contains 9 questions with rating scales from 0 (no pain/no interference) to 10 (worst pain/interferes completely). Total score was calculated as the average of each question. Higher scores represent a higher level of pain or interference. In participants with no pain progression event, time to pain progression was censored on the last visit date where BPI-SF was collected.