A Study for Subjects With Prostate Cancer Who Previously Participated in an Enzalutamide Clinical Study

Inclusion Criteria: * Subject must currently be receiving enzalutamide or assigned to receive enzalutamide (if on treatment suspension) for prostate cancer in a study sponsored by Astellas or Medivation and, based on the investigator's assessment, benefit from continued treatment. Subjects participating in investigator-initiated trials are not eligible. * Subject is able to continue on the treatment regimen that they were receiving or were assigned to receive in the prior study. If in the investigator's assessment, a change is needed to the subject's regimen (e.g., dose change in Androgen deprivation therapy (ADT) or dropping of a combination therapy) approval from a medical monitor is required prior to enrollment. * Subject is able to swallow enzalutamide capsules and comply with study requirements. * Subject and female partner who is of childbearing potential must continue to use 2 forms of birth control, of which 1 must be highly effective and 1 must be a barrier method throughout the study and for 3 months after final enzalutamide administration. * Subject agrees to avoid sperm donation during the study and for at least 3 months after final enzalutamide administration. * Subject agrees not to participate in another interventional study while on treatment. Canada Specific: * Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved written Informed Consent and privacy language as per national regulations (e.g., Health Insurance Portability and Account…