Pfizer, Astellas Amend Research Protocol

Pfizer and partner Astellas Pharma said pre-market Friday that they have amended the protocol for the registrational PROSPER trial, a double-blind, placebo-controlled study evaluating the efficacy and safety of Xtandi in patients with non-metastatic castration-resistant prostate cancer.

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.