Pfizer Inc. and Astellas Pharma Inc. announced that a supplemental New Drug Application (sNDA) for Xtandi (enzalutamide) has been accepted for filing and granted Priority Review designation by the US Food and Drug Administration (FDA). If approved, the sNDA would expand the indication of Xtandi to include men with non-metastatic Castration-Resistant Prostate Cancer (CRPC), based on data from the phase 3 PROSPER trial. Xtandi is currently indicated for the treatment of patients with metastatic CRPC.

The FDA grants Priority Review designation to applications for drugs that, if approved, may offer significant improvements in the safety and effectiveness of the treatment of serious conditions when compared to standard applications. Under Priority Review, the FDA aims to take action on an application within six months of receipt, as compared to ten months under standard review. The Prescription Drug User Fee Act (PDUFA) goal date assigned by the FDA is July 2018. In addition, the European Medicines Agency (EMA) has validated the Type II Variation submitted for Xtandi seeking to expand the current indication to the same patient population and started the review process on March 5.

“Once cancer spreads and metastasizes, men with castration-resistant prostate cancer face a daunting prognosis and challenging odds,” said Steven Benner, M.D., senior vice president and global therapeutic area head, Oncology Development, Astellas. “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.”

“Treatment options have been limited for men with non-metastatic CRPC, in whom the only evidence of progressive disease is a rapidly rising PSA,” said Mace Rothenberg, M.D., chief development officer, Oncology, Pfizer Global Product Development. “Xtandi is already established as a standard of care for men with metastatic CRPC. This milestone marks an important step toward our ability to bring Xtandi to CRPC patients in an earlier setting.”

The PROSPER trial evaluated Xtandi plus androgen deprivation therapy (ADT) versus ADT alone in 1,401 patients with non-metastatic CRPC. The study met its primary endpoint, demonstrating that the use of Xtandi plus ADT significantly reduced the risk of developing metastasis or death compared to ADT alone. Adverse events in the PROSPER trial were higher in the enzalutamide plus ADT arm compared to ADT alone (87% vs. 77%), and were generally consistent with those reported in prior enzalutamide clinical trials in patients with metastatic CRPC. Results from the PROSPER trial were presented at the 2018 Genitourinary Cancers Symposium (ASCO GU) in February.

The FDA approved Xtandi in 2012 for the treatment of patients with metastatic CRPC who had previously received docetaxel. In 2014, the FDA approved Xtandi to treat patients with metastatic CRPC.

Xtandi (enzalutamide) is an androgen receptor inhibitor indicated for the treatment of patients with metastatic castration-resistant prostate cancer.