Results published from the Phase 2 TERRAIN trial of Enzalutamide compared to Bicalutamide in metastatic castration-resistant prostate cancer

Astellas Pharma Europe Ltd., a subsidiary of Tokyo-based Astellas Pharma Inc. (TSE:4503), has announced that results from the Phase 2 TERRAIN trial of XTANDITM (enzalutamide) compared to bicalutamide in metastatic castration-resistant prostate cancer (mCRPC) were published in the Lancet Oncology. The article, titled, "Efficacy and Safety of Enzalutamide Versus Bicalutamide for Patients with Metastatic Prostate Cancer (TERRAIN): A Randomised, Double-Blind, Phase 2 Study," appears in the January 13, 2016 online issue, lead author Dr Neal D Shore.The article will be published in a future print issue of the journal.

The TERRAIN study achieved its primary endpoint demonstrating a statistically significant increase in progression-free survival (PFS) for enzalutamide compared to bicalutamide (Hazard Ratio = 0.44; 95% Confidence Interval, 0.34-0.57; p<0.0001). Median PFS was 15.7 months in the enzalutamide group compared to 5.8 months in the bicalutamide group. The observed adverse event profile in TERRAIN appeared consistent with that from Phase 3 enzalutamide trials.

"Now that these data are published, more healthcare professionals will be able to see for themselves the promise of enzalutamide versus bicalutamide in metastatic castration-resistant prostate cancer," said Professor Axel Heidenreich, M.D., Ph.D., Professor and Director, Department of Urology, University Hospital, Cologne, Germany. "Enzalutamide was superior to bicalutamide in all primary and secondary endpoints demonstrating the drug's oncological efficacy. Despite the fact that patients were treated with enzalutamide twice as long as with bicalutamide, no significant interference with quality of life was observed. These findings may have significant implications for the clinical practice."

The median time on treatment in TERRAIN was 11.7 months in the enzalutamide group versus 5.8 months in the bicalutamide group. Serious adverse events were reported in 31% of enzalutamide-treated patients and 23% of bicalutamide-treated patients. Individual Grade 3 or higher adverse events largely occurred at a similar rate (<1% difference) between treatment groups, with the exception of hypertension (7.1% vs. 4.2%) and back pain (2.7% vs. 1.6%), which occurred more frequently in the enzalutamide treatment group. Grade 3 or higher cardiac events were reported in 5% of enzalutamide-treated patients versus 2% of bicalutamide-treated patients. The majority of patients with these events in both treatment groups had cardiovascular risk factors at baseline. Two seizures were reported in the enzalutamide group and one in the bicalutamide group. The most common side effects occurring during treatment and more common in the enzalutamide-treated versus bicalutamide-treated patients included fatigue, back pain, hot flush, hypertension, diarrhoea, weight decrease and pain in extremity.

"TERRAIN is the first head-to-head trial comparing enzalutamide with bicalutamide that evaluated both the efficacy and safety of these agents in the treatment of men with mCRPC," said Claire Thom, Pharm D., Senior Vice President and Oncology Therapeutic Head, Astellas. "We believe these findings add to the already robust body of data for enzalutamide and appear consistent with results across multiple trials and stages of advanced prostate cancer that have been studied. We are pleased Lancet Oncology has chosen to publish these important results."