The phase 3 PROSPER trial evaluating Enzalutamide ( Xtandi ) 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 Enzalutamide 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.

The PROSPER study has shown that Enzalutamide 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.

The PROSPER randomized, double-blind, placebo-controlled, multi-national trial enrolled approximately 1,400 patients with non-metastatic castration-resistant prostate cancer ( CRPC ) at sites in the United States, Canada, Europe, South America and the Asia Pacific region.
PROSPER enrolled patients with prostate cancer that had progressed, based on a rising prostate-specific antigen ( PSA ) level despite androgen deprivation therapy, but who had no symptoms with no prior or present evidence of metastatic disease.
The primary objective of the trial was metastasis-free survival ( MFS ). MFS is a measure of the amount of time that passes until a cancer can be radiographically detected as having metastasized, or spread, to other parts of the body.
The trial evaluated Enzalutamide at a dose of 160 mg taken orally once daily plus ADT, versus placebo plus ADT.

Enzalutamide is the first androgen receptor-inhibitor to demonstrate a statistically significant improvement in metastasis-free survival ( MFS ) in this patient population in a randomized, controlled clinical trial. ( Xagena )

Source: Astellas, 2017