Pfizer, Astellas chase new Xtandi nod with big survival numbers in prostate cancer

When it comes to using Xtandi in hormone-sensitive prostate cancer, Pfizer and Astellas are "really excited," executives have said. And new data shows the partners have reason to be.

Monday, the companies said that in a phase 3 trial of men with metastatic HSPC, a combination of Xtandi and androgen deprivation therapy (ADT) slashed the risk of cancer worsening or death by 61% versus ADT alone. At the time of analysis, patients in the ADT-only group had gone an average of 19.4 months before showing evidence of radiographic disease progression, an endpoint commonly used in prostate cancer trials. In the Xtandi-ADT arm, the median hadn’t yet been reached.

They’re results the drugmakers intend to discuss with regulators around the world as they seek out new nods for Xtandi, they said. Right now, the drug is only cleared to treat prostate cancer that’s castration resistant.

The Xtandi-ADT pairing "has the potential to be an important treatment option for men with prostate cancer that has spread but has not yet become hormone resistant," Andrew Armstrong, M.D., professor of medicine, surgery, pharmacology and cancer biology and director of research in the Duke Cancer Institute’s Center for Prostate and Urologic Cancers, said in a statement.

It also has the potential to get ahead in a market where its rivals from Johnson & Johnson—those would be Zytiga and follow-up drug Erleada—aren’t yet competing. On Pfizer’s recent fourth-quarter conference call, Angela Hwang, president of Pfizer’s biopharmaceuticals group, calledHSPC the opportunity "we’re really excited about." The metastatic patient population grows by about 38,000 new patients per year, and those patients tend to stay on therapy the longest.

Meanwhile, though, Erleada is going after a new nod of its own. Late last month, J&J said investigators had cut short a phase 3 trial of the drug in combination with ADT in patients with metastatic, castration-sensitive prostate cancer after the duo proved it could significantly keep cancer at bay and lengthen patients’ lives. The New Jersey pharma giant is planning to file for approval in mCSPC this year, it said at the time.

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