A study to evaluate the potential increased risk of seizures among Metastatic Castration-Resistant Prostate Cancer (mCRPC) patients treated with enzalutamide

a) Prostate-Specific Antigen (PSA) progression defined by a minimum of 2 rising PSA levels with an interval of at least 1 week between each draw;

b) Bone disease progression as defined by Prostate Cancer Working Group 2 guidelines (at least 2 new lesions) on bone scan; or

c) Soft tissue disease progression as defined by RECIST 1.1

a) past history of seizure due to any cause except a single febrile seizure in childhood. Patients with a history of seizures should not have had a seizure within 12 months of Screening and must have had no anticonvulsants for 12 months prior to Screening,

b) history of cerebrovascular accident (CVA) or transient ischemic attack (TIA),

c) history of traumatic brain or head injury with loss of consciousness

d) unexplained loss of consciousness within the last 12 months,

e) presence of a space occupying lesion in the brain including previously treated brain metastasis(es) or primary central nervous system (CNS) tumor,

f) history of arteriovenous malformations of the brain,

g) history of brain infection (i.e., abscess, meningitis, or encephalitis),

h) current use of medication that may lower seizure threshold

i) presence of Alzheimer's disease, meningioma, leptomeningeal disease from prostate cancer.

1. Two acceptable forms of birth control include:

a) Condom (barrier method of contraception), AND

b) One of the following acceptable forms of contraception is required:

1. Established use of oral, injected or implanted hormonal methods of contraception.

2.Placement of an intrauterine device (IUD) or intrauterine system (IUS).

3.Barrier methods of contraception: Occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/suppository).

4.Vasectomy or surgical castration at least 6 months prior to Screening.