FDA Grants Priority Review for Prostate Cancer Treatment

A little more than one month after Pfizer Inc. and partner Astellas Pharma unveiled impressive Phase III data for the efficacy of Xtandi in non-metastatic Castration-Resistant Prostate Cancer (CRPC), the companies said a supplemental New Drug Application with the U.S. Food and Drug Administration was accepted.

Additionally, the two companies jointly said the FDA granted a Priority Review designation to the sNDA for the combination of Xtandi and androgen deprivation therapy (ADT). If the FDA approves the sNDA, that would expand the indication of Xtandi (enzalutamide). The drug has already been approved for the treatment of patients with metastatic CRPC. The FDA is expected to make a decision on the expanded indication in July.

If approved, the new indication for Xtandi will provide a competitive edge over Johnson & Johnson Family of Companies’s Zytiga. In February the FDA approved a combination of Zytiga and prednisone as a treatment of patients with metastatic high-risk castration-sensitive prostate cancer.

In addition to the movement with the FDA, the companies said the European Medicines Agency (EMA) has validated the Type II Variation to expand the use of Xtandi to the same patient population overseas.

Prostate cancer is the second most common cancer in men worldwide, with about 164,000 expected diagnoses in the United States this year. Castration-resistant prostate cancer refers to the subset of men whose prostate cancer progresses despite castration levels of testosterone. Xtandi was approved in 2012 for late-stage prostate cancer.

The Phase III trial showed that a combination of Xtandi plus ADT significantly reduced the risk of developing metastases or death by 71 percent. Not only did the combination treatment reduce the risk of metastases, trial data showed the combination had a 93 percent reduction in relative risk of prostate-specific antigen (PSA) progression, which is a biomarker tied to the worsening of a disease, compared to patients who received ADT alone. The combination delayed the median time to PSA progression by 33.3 months compared to 3.9 months of ADT treatment alone, according to the data. In addition to those data points, the companies said the combination of Xtandi and ADT prolonged the median time to time to first use of new antineoplastic therapy by 21.9 months versus ADT alone.

"Once cancer spreads and metastasizes, men with castration-resistant prostate cancer face a daunting prognosis and challenging odds," Steven Benner, Astellas’ global therapeutic area head for said in a statement. "We're pleased to see the FDA's Priority Review designation as we work to potentially bring Xtandi to men living with non-metastatic CRPC."

Mace Rothenberg, Pfizer’s chief oncology development officer, said treatment options are limited for men with non-metastatic CRPC. He said Xtandi has already been established as a standard of care for men with metastatic CRPC and an approval for the expanded indication will allow the medication to be used for patients in an earlier disease setting.

Astellas and Pfizer said adverse events in the Prosper Trial were consistent with previous enzalutamide clinical trials in patients with metastatic CRPC. Grade 3 or higher adverse events, such as hypertension, were reported in 31 percent of men treated with XTANDI plus ADT and in 23 percent of men treated with ADT alone

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