Prosper: a Phase 3 Study of Enzalutamide in Non-Metastatic (M0) Castration-Resistant Prostate Cancer (Crpc) Patients

Abstract

Background: There is no standard of care for patients with M0 CRPC. In a recent study, patients with a PSA >=8 ng/mL or PSA doubling time of =2 ng/mL; and adequate hematologic, hepatic, and renal function. Approximately 1560 patients will have continued androgen deprivation therapy and will be randomized 2:1 to enzalutamide 160 mg/day or placebo. Patients will be stratified by PSA doubling time (<6 vs 6-10 months) and baseline use of bone-targeting agent (yes vs no).The primary endpoint is metastasis-free survival (MFS) based on central independent review of whole-body radionuclide bone scans for bone disease assessment and CT or MRI scans for soft tissue disease assessment. Imaging will be undertaken at screening and every 16 weeks post randomization till radiographic progression. The study has 90% power to detect a target hazard ratio of 0.75 based on a 2-sided log-rank test at an overall significance level of 0.05. Secondary endpoints include: overall survival; time to pain progression; time to opiate use for prostate cancer pain; time to first use of cytotoxic chemotherapy; time to first use of new antineoplastic therapy; time to PSA progression; PSA response; time to functional status deterioration as assessed by the FACT-P global score; and quality of life as assessed by EQ-5D-5L and QLQ-PR25.