Amendment to PROSPER trial clinical research protocol could accelerate top-line results

Astellas Pharma and Pfizer have announced an amendment to the clinical research protocol for the Phase III PROSPER trial evaluating XTANDI (enzalutamide) in patients with non-metastatic (M0) castration-resistant prostate cancer (CRPC), which could speed up the release of the top-line results by two years.

The main purpose of the revision to the protocol is to adjust the plan for the analyses of the primary and several secondary endpoints, allowing for a reduction in the target sample size from 1,560 to 1,440 patients. It was previously anticipated that the primary completion date for the trial would be June 2019, but the companies now expect top-line results will be released later this year.

“XTANDI is already a standard of care for men worldwide fighting metastatic CRPC, but we are continually looking to evaluate this medicine for men facing earlier stage disease,” said Dr Steven Benner, 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.”

“PROSPER is one of a number of large, randomised trials in our robust, registration-focused development programme, where we are evaluating enzalutamide in different prostate cancer populations, including men with earlier stages of the disease,” added Dr Mace Rothenberg, chief development officer, Oncology, Pfizer Global Product Development. “We look forward to building upon the extensive body of clinical evidence that has been generated over the past five years and established XTANDI as a standard of care for men with metastatic CRPC.”