Study on Enzalutamide and Flutamide in Patients With Castration Resistant Prostate Cancer

A Randomized Phase IV Study Comparing Enzalutamide Versus Flutamide in Castration-resistant Prostate Cancer (CRPC) Patients Who Have Failed Combined Androgen Blockade Therapy With Bicalutamide Plus Androgen Deprivation Therapy (ADT)

The objective of this study was to compare the efficacy and safety of the combination therapy with enzalutamide + androgen deprivation therapy (ADT) and the combination therapy with flutamide + ADT in patients with castration resistant prostate cancer who had relapsed during combined androgen blockade (CAB) therapy with bicalutamide and ADT. This study also investigated the order of alternative antiandrogen therapy (AAT) by changing the 1st line medication after relapse of prostate-specific antigen (PSA).

Inclusion Criteria:

• Subject is diagnosed with histologically or cytologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation or small-cell histology.
• Subject on continuous ADT with Gonadotropin Releasing Hormone (GnRH) agonist/antagonist or bilateral orchiectomy.
• Serum testosterone level below the target level at screening visit.
• Subject with asymptomatic or mildly symptomatic prostate cancer.
• Subject has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Subject has progression of the disease as defined by rising PSA levels or progressive soft tissue or bony disease during CAB therapy in combination of bicalutamide and ADT.
• A sexually active male subject and the subject's female partner who is of childbearing potential must use 2 acceptable birth control methods from screening to 3 months after the last dose of the study drug.
• Subject must agree not to donate sperm from screening to 3 months after the last dose of the study drug.

Exclusion Criteria:

• Subject with severe concurrent diseases, infections, or complications.
• Subject with confirmed or suspected brain metastasis or active leptomeningeal metastasis.
• Subject with a history of malignant tumor other than prostate cancer in the past 5 years.
• Subject hypersensitive to the ingredients of enzalutamide capsules or flutamide tablets.
• Subject with a history of convulsive attack, or prone to convulsive attack.
• Subject with liver disorder such as viral hepatitis and hepatic cirrhosis, or subject with Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) at screening visit higher than the upper limit of normal.
• Subject received treatment for prostate cancer with cytocidal chemotherapy that includes anti androgenic agents other than bicalutamide, abiraterone, or estramustine.