Phase III PROSPER trial of Xtandi (enzalutamide) plus androgen deprivation therapy (ADT) versus ADT alone for non-metastatic castration-resistant prostate cancer met its primary endpoint of improved metastasis-free survival.- Pfizer + Astellas

Pfizer Inc.and Astellas Pharma Inc. have announced that the Phase III PROSPER trial evaluating Xtandi (enzalutamide) plus androgen deprivation therapy (ADT) versus ADT alone in patients with non-metastatic (M0) Castration-Resistant Prostate Cancer (CRPC) met its primary endpoint of improved metastasis-free survival (MFS). The preliminary safety analysis of the PROSPER trial appears consistent with the safety profile of Xtandi in previous clinical trials.

“Many prostate cancer patients who initiate androgen deprivation therapy will experience disease progression illustrated by a rising PSA level, and currently, there are no FDA-approved treatment options for patients with non-metastatic CRPC until they develop confirmed radiographic metastatic disease,” said Neal Shore, M.D., director, CPI, Carolina Urologic Research Center. Based on the results of PROSPER, the companies intend to discuss the data with global health authorities to potentially support expanding the label for Xtandi to cover all patients with CRPC. Xtandi plus ADT delayed clinically detectable metastases compared to ADT alone in patients with non-metastatic CRPC whose only sign of underlying disease was a rapidly rising prostate-specific antigen (PSA) level. As part of Pfizer and Astellas’ ongoing commitment to the clinical development of enzalutamide in areas of greatest unmet need, the companies initiated the PROSPER trial to evaluate the potential benefits of Xtandi in men with non-metastatic CRPC, an earlier stage of prostate cancer where there are currently no FDA-approved treatment options. On June 9, 2017, the companies announced an amendment to the PROSPER protocol, which accelerated the clinical trial completion date by two years. Xtandi is currently approved for the treatment of metastatic CRPC based on clinical data from previous studies that showed a statistically significant overall survival benefit for Xtandi versus placebo in the metastatic CRPC setting. Xtandi has been prescribed to more than 185,000 patients globally since its first approval in 2012.