Enzalutamide (Xtandi) Delays Metastasis in Hormone-Resistant Prostate Cancer

Adding Xtandi® (enzalutamide) to hormone therapy reduces the risk of cancer spreading in patients with non-metastatic, hormone-resistant prostate cancer (CRPC), new Phase 3 trial data shows. Additional results were announced by Pfizer and Astellas Pharma, the drug developers. “Many prostate cancer patients who initiate hormone 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,” according to Dr. Neal Shore, MD, director, Carolina Urologic Research Center.

Pfizer and Astellas initiated the multinational PROSPER trial to determine the effects of Xtandi® in men with non-metastatic CRPC. The trial enrolled approximately 1,400 patients with prostate cancer that had progressed, based on rising PSA levels, despite androgen deprivation (hormone) therapy (ADT) but with no symptoms or other evidence of metastasis. Participants were randomly assigned Xtandi® plus hormone therapy or a placebo plus hormone therapy. The study’s primary endpoint was metastasis-free survival, which is the amount of time passed until the cancer spread.

Results seen in the PROSPER study showed that Xtandi® 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.  Xtandi® is already established as a standard of care for men with metastatic CRPC based on the results of prior studies, such as AFFIRM and PREVAIL, which demonstrated that Xtandi® delayed disease progression and improved overall survival in men with clinically detectable metastatic disease. For additional information, see the following link.

It seems that Xtandi® (enzalutamide) and ARN-509 (apalutamide) share similar biological properties and mechanisms of action. Perhaps there differences in pharmacologic properties due to their differing chemical structures but they seem similar. (See the Nov. 10th post for comparison.)

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