A late-stage trial assessing Astellas/Medivation's Xtandi in prostate cancer has been stopped early after the drug showed clear benefits in overall and progression-free survival in pre-chemo patients.

The global Phase III PREVAIL study was assessing the drug in more than 1,700 men with metastatic prostate cancer that has progressed despite androgen deprivation therapy and who have not yet received chemotherapy. 

A planned interim analysis by Independent Data Monitoring Committee showed that, in this setting, Xtandi (enzalutamide) provided a 30% reduction in risk of death compared with placebo, and an 81% reduction in risk of radiographic progression or death.

The percentage of patients alive in the Xtandi arm was 72% compared with 65% in the placebo arm at the time of the interim analysis data cut-off date, the firms reported.

The findings have sparked some excitement among experts.

“To my knowledge, the benefits in overall survival and radiographic progression-free survival reported in today's PREVAIL trial results are unprecedented in this patient population,” said Tomasz Beer, professor of medicine and deputy director of the Knight Cancer Institute at Oregon Health & Science University, and the co-principal investigator of the PREVAIL study.

On the back of the data, more details on which will be presented at a future medical conference, the companies said they will initiate meetings with and submissions to regulatory agencies beginning in early next year.

Xtandi is already on the market for the treatment of men with metastatic castration-resistant prostate cancer whose disease has progressed on or after docetaxel therapy. But industry observers believe that extending its remit to the 'pre-chemo' population will help it attain coveted blockbuster status (reports TheStreet).