New data positions Astellas prostate cancer med Xtandi to grab market share from J&J's Zytiga

Some new data on the prostate cancer drug Xtandi promises to heat up competition with Johnson & Johnson's ($JNJ) Zytiga. Medivation ($MDVN) and its partner Astellas Pharma unveiled final data from a late-stage trial showing that Xtandi (enzalutamide) prolonged patients' lives and delayed tumor growth when used before chemotherapy.

The study paves the way for broader use of Xtandi, which was approved in 2012 for metastatic prostate cancer in men who had already been treated with the chemo drug docetaxel. An approval for pre-chemo use would put Xtandi on more even footing with Zytiga (abiraterone), which won approval for pre-chemo use last year. Medivation shares leapt 12% on the news.

The study of more than 1,700 patients compared Xtandi to placebo, finding that the drug reduced the risk of death by 29% and the risk of disease progression or death by 81%, compared with the sugar pill. The trial had been expected to continue until September of this year, but Xtandi proved so effective that the trial was stopped in October. Details of the results are only just now available.

After perusing those details, some analysts believe Xtandi could beat Zytiga. Jefferies & Co. analyst Biren Amin told Bloomberg that Xtandi topped Zytiga "on every metric," including survival, PSA response and time to chemo. Amin now expects Xtandi to hit $866 million in sales this year, up from his previous estimate of $645 million. Meanwhile, JPMorgan analyst Geoffrey Meacham called the new data "very impressive" and said it helps "solidify Xtandi's place ahead of Zytiga in the pre-chemo setting."

"In our view, the full ... data of Xtandi in pre-chemo prostate cancer leave little room for debate on whether Xtandi or J&J's Zytiga will have majority market share," Meacham said in a note to investors. "[I]n our judgment, many of the efficacy metrics definitively favor Xtandi."

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