Updated Phase III data for Xtandi (enzalutamide) in Prostate Cancer-Astellas

Astellas Pharma has announced an updated overall survival analysis from the placebo-controlled Phase III PREVAIL trial of Xtandi (enzalutamide) in chemotherapy-naive metastatic castration-resistant prostate cancer. The trial is a randomised, double-blind, placebo-controlled, multi-national trial, which enrolled 1,717 patients at sites in the United States, Canada, Europe, Australia, Russia, Israel and Asia, including Japan.

An updated overall survival analysis was conducted at 784 deaths and found a statistically significant overall survival benefit with a 23% reduction in risk of death and a 4-month improvement in median survival with enzalutamide (35.3 months) over placebo (31.3 months). As of the June 2014 cut-off date with a median follow-up duration of 31 months, 52% of enzalutamide and 81% of placebo patients received less than 1 subsequent life-extending prostate cancer therapy. The data were presented during a plenary session at the 2015 European Association of Urology (EAU) Congress.

Comment: According to an independent appraisal committee at the UK NICE, while both Xtandi and Zytiga are oral treatments, only Xtandi can be taken on a full stomach, making it more convenient to take. In addition, Xtandi can help control the cancer longer because there is no need to reduce the dose to prevent liver toxicity, as can occur with Zytiga. Analysts expect Xtandi to eventually overtake Zytiga despite the latter's head start.