Trial to evaluate continued advanced prostate cancer treatment

Astellas Pharma US, Inc. and Medivation, Inc. have initiated a phase IV trial to evaluate the benefit of continued treatment with enzalutamide (Xtandi) beyond disease progression in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer.

Known as PLATO, the trial will evaluate the efficacy and safety of continued treatment with enzalutamide plus abiraterone (ZYTIGA) and prednisone as compared to treatment with abiraterone and prednisone alone in patients with chemotherapy-naïve metastatic prostate cancer whose disease has progressed following enzalutamide therapy.

“This phase IV study offers an important opportunity to help determine the potential clinical benefit of extending time on enzalutamide treatment by adding an additional therapy in patients with progressive chemotherapy-naïve metastatic prostate cancer,” said David Hung, MD, of Medivation. “This trial underscores our continued commitment to discovering how enzalutamide can be used most effectively to benefit prostate cancer patients across the disease continuum.”

The global randomized, double-blind, placebo-controlled trial is designed to enroll approximately 500 chemotherapy-naïve patients with metastatic castration-resistant prostate cancer. All enrolled patients will initially receive treatment with enzalutamide. Eligible patients with disease progression on enzalutamide will be randomized to treatment with enzalutamide plus abiraterone and prednisone or to abiraterone and prednisone. The primary endpoint of the trial is progression-free survival.

The trial will evaluate enzalutamide at a dose of 160 mg taken orally once daily in combination with abiraterone at a dose of 1,000 mg administered orally once daily and prednisone at a dose of 5 mg administered orally twice daily, versus placebo plus the same doses of abiraterone and prednisone.

Enzalutamide is currently approved for the treatment of patients with metastatic castration-resistant prostate cancer who have previously received docetaxel (Taxotere). Last month, Astellas and Medivation said that a phase III trial of the drug in chemotherapy-naïve patients with advanced prostate cancer met both of its primary endpoints, and the trial was stopped early so that placebo recipients could be offered enzalutamide. 

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