Does enzalutmide improve survival in nonmetastatic, castration-resistant prostate cancer?

The study assessed whether enzalutamide (Xtandi) plus androgen deprivation therapy (ADT) increased overall survival (OS) of patients with nonmetastatic, castration-resistant prostate cancer (CRPC). The study found improved survival in patients with CRPC treated with enzalutamide.

ADT is a type of hormonal therapy that blocks the release or action of male sex hormones such as testosterone that may fuel prostate cancer growth. CRPC is a form of prostate cancer that is not responsive to ADT. Other therapies in addition to ADT are necessary for patients with non-metastatic (not spread to distant organs) CRPC. 

Enzalutamide is an oral hormonal therapy that is used to treat nonmetastatic CRPC. Enzalutamide can be given with ADT. It has been associated with a lower risk of spread in CRPC. Enzalutamide has been associated with an improved quality of life, increased time to further anti-cancer therapy in patients with CRPC. However, the long-term overall survival of patients with non-metastatic CRPC treated with enzalutamide is still under investigation.

There were 1401 patients included in the study. 933 patients randomly received enzalutamide and ADT. 468 patients received a placebo and ADT. The average follow-up for all groups was 48 months. 

The average overall survival (OS) was 67.0 months for the enzalutamide group. The average OS in the placebo group was 56.3 months. Enzalutamide resulted in a 27% lower risk of death when compared to the placebo group. 

The average time for the enzalutamide group to use further anti-cancer therapy was 66.7 months. The amount of time to further anti-cancer therapy for the placebo group was 19.1 months. Enzalutamide was associated with a 71% longer time until the need for further anti-cancer therapy compared to placebo.

The rates of side effects were similar in both the enzalutamide group and the placebo group. The most common serious side effects more frequent for the enzalutamide group were falls and fractures. The most common reason to stop the trial in the enzalutamide group and the placebo group was progression of disease. 

The authors concluded that treatment with enzalutamide plus ADT increased the survival of men with nonmetastatic, CRPC. 

Results from the final report of OS have not been reported yet. Enzalutamide is currently approved by the FDA to treat nonmetastatic, CRPC together with ADT. The study was funded by Astellas, and Pfizer, co-developers of enzalutamide.