The PREVAIL trial studied 17,000 men with asymptomatic or mildly symptomatic, metastatic, castration-resistant prostate cancer who had received androgen-deprivation therapy but not chemotherapy. The men were randomized to receive daily enzalutaminde (an androgen-receptor antagonist) or placebo.
At 12 months, radiographic progression-free survival was higher in the enzalutamide group (65% versus 14%, respectively). Enzalutamide reduced the risk of radiographic progression by 81% and delayed the need for chemotherapy by a median of 17 months. Median time to chemotherapy was 28 months in the enzalutamide group versus 10.8 months in the placebo arm.