Medivation, Astellas' Xtandi garners FDA approval for prostate cancer

The FDA approved Medivation and Astellas' Xtandi (enzalutamide) after a priority review for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) who previously received chemotherapy, the companies announced Friday. "The need for additional treatment options for advanced prostate cancer continues to be important for patients," said Richard Pazdur, director of haematology and oncology products at the FDA's Center for Drug Evaluation and Research, adding that "Xtandi is the latest treatment for this disease to demonstrate its ability to extend a patient's life."

The approval, which came ahead of the November 22 priority review date, was based on results of the Phase III AFFIRM trial, which randomised 1199 patients with mCRPC previously treated with docetaxel to receive Xtandi daily or placebo. Data showed that median overall survival was significantly higher at 18.4 months in the Xtandi group, versus 13.6 months in the placebo arm. The companies noted that the therapy provided a 37-percent reduction in risk of death compared to placebo.

In the trial, seizure occurred in 0.9 percent of patients given Xtandi, compared to none in the placebo arm. As a post-marketing requirement, the drugmakers agreed to conduct an open-label safety study of the therapy in patients who are at high risk for seizure, and to provide data from this study in 2019.

The companies expect to make the once-daily androgen receptor inhibitor available to patients in mid-September at a wholesale price of $7450 per month, according to Medivation CEO David Hung, who specified that the median patient received the drug as part of the trial for about eight months. Leerink Swann analyst Howard Liang said Xtandi "looks to be the best drug so far for prostate cancer, which is a big category, a big market." Medivation is currently conducting a clinical trial to assess if the drug offers a benefit for patients in the pre-chemotherapy setting.

Analysts project that the approval may increase Medivation's sales to $357 million in 2013 from $60 million last year, with forecasts of $1.2 billion by 2017. European regulators are currently reviewing an application for approval of the drug for men with mCRPC previously treated with chemotherapy.

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