The US Food and Drug Administration has expanded the use of Medivation’s advanced prostate cancer drug Xtandi (enzalutamide) to include patients who have not yet received chemotherapy, significantly extending the drug’s potential reach.

Xtandi’s first regulatory green light in 2012 allowed its use in men with metastatic castration-resistant prostate cancer but only after having received an initial batch of chemotherapy.

The approval, which has triggered a $90 million milestone payment from Astellas, was based on data from the Phase III PREVAIL trial, showing that the drug significantly cut the risk of death by 29% compared with placebo and also the risk of radiographic progression or death by 83%.

Also, the median time to starting chemotherapy was delayed by 17 months with Xtandi compared to placebo, “so the result is a meaningful period of time during which men have their disease controlled without the need for chemotherapy,” noted co-lead trial investigator Tomasz Beer, deputy director of the Knight Cancer Institute and professor of medicine at Oregon Health & Science University.

The new indication, which is also under review in Europe, should help the drug compete more closely with Johnson & Johnson's rival drug Zytiga (abiraterone).