The PREVAIL Study: Primary Outcomes by Site and Extent of Baseline Disease for Enzalutamide-treated Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer

Background: Enzalutamide, an oral androgen receptor inhibitor, significantly improved overall survival (OS) and radiographic progression-free survival (rPFS) versus placebo in the PREVAIL trial of men with chemotherapy-naïve metastatic castration-resistant prostate cancer. Objective: To assess the effects of enzalutamide versus placebo in patients from PREVAIL based on site and extent of baseline disease. Design, setting, and participants: One thousand seven hundred and seventeen asymptomatic or minimally symptomatic patients were randomized to enzalutamide (n = 872) or placebo (n = 845). Subgroup analyses included nonvisceral (only bone and/or nodal; n = 1513), visceral (lung and/or liver; n = 204), low-volume bone disease (1 in patients with visceral disease (HR, 0.82; 95% CI, 0.55-1.23). Enzalutamide was well tolerated in patients with or without visceral disease. Conclusions: Enzalutamide provided clinically significant benefits in men with chemotherapy-naïve metastatic castration-resistant prostate cancer, with or without visceral disease, low- or high-volume bone disease, or lymph node only disease. Patient summary: Patients with metastatic castration-resistant prostate cancer-including those with or without visceral disease or widespread bone disease-benefitted from enzalutamide, an active well-tolerated therapy. Enzalutamide provided meaningful clinical benefit to men with chemotherapy-naïve metastatic castration-resistant prostate cancer, with or without visceral disease. Patients without visceral disease particularly benefitted from enzalutamide, an active therapy with good tolerability that allowed for a long duration of treatment.