Phase 3 Study Shows XTANDI® (enzalutamide) plus Leuprolide Significantly Improves Metastasis-Free Survival in Men with Non-Metastatic Prostate Cancer

Pfizer and Astellas Pharma have announced positive topline results from the Phase 3 EMBARK trial study evaluating XTANDI® (enzalutamide) in men with non-metastatic hormone-sensitive prostate cancer with high-risk biochemical recurrence (BCR). Patients enrolled in the trial were randomized to one of three study arms: XTANDI plus leuprolide, placebo plus leuprolide, or XTANDI monotherapy. The study met its primary endpoint with a statistically significant and clinically meaningful improvement in metastasis-free survival (MFS) for patients treated with XTANDI plus leuprolide versus placebo plus leuprolide.

At the time of the analysis, a positive trend in the key secondary endpoint of overall survival (OS) was also observed, but these data were not yet mature. Patients in the trial will be followed for a subsequent final OS analysis. The study also met a key secondary endpoint with a statistically significant and clinically meaningful improvement in MFS for patients treated with XTANDI monotherapy versus placebo plus leuprolide. Additional key secondary endpoints reached statistical significance, including time to prostate-specific antigen (PSA) progression and time to first use of new antineoplastic therapy. Other secondary endpoints are being analyzed. No new safety signals have been observed to date in the preliminary safety analysis, which is consistent with the established safety profile of XTANDI.

“As the only novel hormone therapy approved for three disease states of prostate cancer in the U.S., XTANDI has impacted hundreds of thousands of men,” said Chris Boshoff, M.D., Ph.D., Chief Development Officer, Oncology and Rare Disease, Pfizer Global Product Development. “The topline findings from EMBARK are highly encouraging and we look forward to engaging with health authorities to potentially bring XTANDI to men with non-metastatic hormone-sensitive prostate cancer with high-risk biochemical recurrence.”

“While current treatment options for localized prostate cancer are intended to be curative, some men remain at higher risk for biochemical recurrence following primary treatment, which may result in metastases,” said Ahsan Arozullah, M.D., MPH, Senior Vice President and Head of Development Therapeutic Areas, Astellas. “The EMBARK trial is the first study to demonstrate a statistically significant improvement in MFS using the combination of XTANDI plus leuprolide in men with this stage of disease.”

Detailed results from EMBARK will be presented at a future medical meeting. These data will also be discussed with regulatory authorities, including the U.S. Food and Drug Administration (FDA), to support a potential regulatory submission for XTANDI in this indication.