Hormone Therapy for Early-stage Prostate Cancer

The FDA has approved enzalutamide for non-metastatic prostate cancer that is sensitive to antiandrogen therapy. 

The U.S. Food and Drug Administration (FDA) has approved enzalutamide (Xtandi) for the treatment of non-metastatic castration-sensitive prostate cancer that has experienced a biochemical recurrence that indicates a high risk of metastasis. 

3D illustration showing prostate cancer with the presence of tumor inside the prostate gland, which compresses the urethra.

Prostate cancer is classified as castration-sensitive if it responds to either surgical castration or drug-based treatments to reduce the amount of androgen hormones in the body. If the cancer stops responding to these treatments, it becomes castration resistant, and other antiandrogen therapies may be used to help control it.  

A biochemical recurrence, defined as a rise in levels of prostate specific antigen (PSA) found in blood, is a sign the cancer may be progressing; if the biochemical recurrence happens after the prostate has been removed, it may indicate metastatic disease. 

Enzalutamide blocks the androgen receptor in prostate cancer cells. It has been previously approved for metastatic prostate cancer—both castration-resistant and castration-sensitive—as well as for non-metastatic castration-resistant disease. 

This approval was based on results from the randomized, controlled, phase III EMBARK clinical trial that enrolled 1,068 patients with non-metastatic castration-sensitive prostate cancer with a high-risk biochemical recurrence (PSA doubling time ≤ 9 months). Patients had received a radical prostatectomy and/or radiation to shrink the tumor. 

Patients were randomly assigned (1:1:1) to receive enzalutamide, enzalutamide plus the sex hormone suppressor leuprolide, or placebo plus leuprolide. Patients who received enzalutamide alone and those who received enzalutamide plus leuprolide were 37% and 58% less likely to experience metastasis or death, respectively, than those who received placebo plus leuprolide. 

Prostate cancer is the most common non-skin cancer diagnosed in men. According to federal statistics, it was estimated that 288,300 individuals would be diagnosed with prostate cancer and 34,700 patients would die of the disease in the United States in 2023. 

The FDA rendered its decision on November 16, 2023.