PROSPER trial protocol of Xtandi (enzalutamide) in patients with non-metastatic castration-resistant prostate cancer is amended.- Astellas and Pfizer

Astellas Pharma Inc. and Pfizer Inc.announced the amendment of the protocol for the registrational PROSPER trial, a multi-national, randomized, double-blind, placebo-controlled study evaluating the efficacy and safety of Xtandi (enzalutamide) in patients with non-metastatic (M0) Castration-Resistant Prostate Cancer (CRPC). The primary endpoint remains the same: metastasis-free survival (MFS).

The main purpose of the amendment is to revise the plan for the analyses of the primary and several secondary endpoints, which allows for a reduction in the target sample size to approximately 1,440, from 1,560 patients. The companies now anticipate PROSPER top-line results will be disclosed later this year. Previously the expected primary completion date for PROSPER was June 2019.

"Xtandi is already a standard of care for men worldwide fighting metastatic castration-resistant prostate cancer, but we are continually looking to evaluate this medicine for men facing earlier stage disease,” said Steven Benner, M.D., senior vice president and global therapeutic area head, oncology development, Astellas. “By amending the protocol for PROSPER, we hope to be able to accelerate the evaluation of the data in this area of medical need.”

Xtandi is approved by the FDA for the treatment of patients with metastatic CRPC, based on clinical studies showing statistically significant overall survival benefit versus placebo. Xtandi was EU approved in 2013.