['adenocarcinoma of the prostate', 'recurrent prostate cancer', 'stage iv prostate cancer']
['enzalutamide', 'bicalutamide', 'leuprolide acetate', 'goserelin acetate']

        Inclusion Criteria:

          -  Histologically confirmed prostate adenocarcinoma with metastasis either starting or
             recently started on LHRH analogue therapy. [Late induction permitted within 3 months
             of starting LHRH analogue therapy or antiandrogen]

          -  All patients who have not initiated hormone therapy (Early induction patients) must
             have elevated PSA ≥ 4 ng/ml within 28 days prior to registration. For late induction
             registrations, PSA must be ≥ 4 ng/ml prior to start of androgen deprivation therapy;
             either antiandrogen or LHRH analogue or GNRH antagonist .If patients are on
             antiandrogen, this will need to be discontinued for at least 7 days prior to
             registration.

          -  Patients with a history of prior neoadjuvant or adjuvant hormone therapy are eligible
             provided they have received twenty four or less months of hormone treatment (single or
             combination treatment, excluding orchiectomy). Both therapies (neoadjuvant/adjuvant
             hormone therapy) must have been discontinued at least 6 months prior to registration.
             This is intended to exclude patients who might have been rendered indirectly androgen
             insensitive.

          -  There must be no plans to receive concomitant chemotherapy, biological response
             modifiers, radiation therapy or hormonal therapy. Concomitant radiation therapy is
             allowed for the palliation of severe pain/neuropathic compression. Prior or
             concomitant use of megestrol acetate for the treatment of hot flashes is allowed.

          -  Patients must have a performance status of 0 - 2 by Zubrod Criteria.

          -  Patients must have recovered from any major infections and/or surgical procedures
             and,in the opinion of the investigator, not have significant active medical illness
             precluding protocol treatment or survival.

          -  No prior malignancy is allowed except for adequately treated basal cell (or squamous
             cell) skin cancer, superficial or in situ cancer of the bladder. For an invasive
             cancer the patients should be disease free for at least 3 years prior to enrollment on
             study.

          -  For all patients a bone scan must be performed within 60 days prior to registration
             for tumor assessment. CT scans (abdomen and pelvis) and chest x-ray are optional, but
             must be repeated if used for disease assessment. For late induction registrations,
             tumor assessment imaging showing metastatic disease must be available prior to start
             of androgen deprivation therapy.

          -  Age 18 or older and willing and able to provide informed consent.

          -  Willingness to swallow pills and no medical condition that would interfere with this.

          -  Male patient and his female partner who is of childbearing potential must use 2
             acceptable methods of birth control (one of which must include a condom as a barrier
             method of contraception) starting at screening and continuing throughout the study
             period and for 3 months after final study drug administration. Patients are also
             required to use a condom if having sex with a pregnant woman.

          -  Patient should agree to a tumor tissue biopsy prior to protocol enrollment. Post
             therapy biopsy is optional.

          -  Patients who are being treated with a GNRH antagonist should be willing to switch to a
             LHRH analogue after registration.

          -  Patients must have one of the following a) Low volume disease (defined as no visceral
             metastases and < 4 bone metastases) or b) are not candidates for docetaxel based
             chemotherapy or 3) refused docetaxel chemotherapy

        Exclusion Criteria:

          -  History of seizure or any condition that may predispose to seizure (e.g., prior
             cortical stroke, significant brain trauma) at any time in the past. Also, history of
             loss of consciousness or transient ischemic attack within 12 months of Day 1 visit;

          -  Known or suspected brain metastasis or active leptomeningeal disease;

          -  Severe concurrent disease, infection, or co-morbidity that, in the judgment of the
             Investigator, would make the patient inappropriate for enrollment;

          -  Absolute neutrophil count < 1,000/μL, or platelet count < 50,000/μL, or hemoglobin<8
             g/dL) at the Screening visit.

          -  Total bilirubin, alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >
             2.5 times the upper limit of normal

          -  Creatinine > 177 μmol/L (2 mg/dL)

          -  Clinically significant cardiovascular disease including: Myocardial infarction within
             6 months; Uncontrolled angina within 3 months; Congestive heart failure New York Heart
             Association (NYHA) class 3 or 4, or patients with history of congestive heart failure
             (NYHA) class 3 or 4 in the past, unless screening echocardiogram or multi-gated
             acquistion scan performed within 3 months results in a left ventricular ejection
             fraction that is greater or equal to 45%; History of clinically significant
             ventricular arrhythmias (e.g., ventricular tachycardia, ventricular fibrillation,
             torsades de pointes); History of Mobitz II second degree or third degree heart block
             without a permanent pacemaker in place; Hypotension as indicated by systolic blood
             pressure < 86 millimeters of mercury (mmHg) at the Screening visit; Bradycardia as
             indicated by a heart rate of < 50 beats per minute on the Screening ECG; Uncontrolled
             hypertension as indicated by systolic blood pressure > 170 mmHg or diastolic blood
             pressure > 105 mmHg

          -  Gastrointestinal disorder affecting absorption (e.g., gastrectomy, active peptic ulcer
             disease within last 3 months);

          -  Treatment with concurrent 5-α reductase inhibitors (finasteride, dutasteride),
             estrogens, and/or cyproterone

          -  Treatment with systemic biologic therapy for prostate cancer (other than approved bone
             targeted agents and GnRH-analogue therapy) or other agents with anti-tumor activity
             within 4 weeks of enrollment (Day 1 visit);

          -  History of prostate cancer progression on ketoconazole;

          -  Prior use, or participation in a clinical trial, of an investigational agent that
             blocks androgen synthesis (e.g., abiraterone acetate, TAK-700, TAK-683, TAK-448) or
             agents that block the androgen receptor (e.g.,ARN-509)

          -  Previous enzalutamide therapy;

          -  Use of an investigational agent within 2 weeks of enrollment (Day 1 visit);

          -  Use of herbal products that may have hormonal anti-prostate cancer activity and/or are
             known to decrease PSA levels (e.g., saw palmetto) or systemic corticosteroids greater
             than the equivalent of replacement steroids or > equivalent of 10 mg of prednisone
             perday within 4 weeks of enrollment (Day 1 visit);

          -  Any condition or reason that, in the opinion of the Investigator, interferes with the
             ability of the patient to participate in the trial, which places the patient at undue
             risk, or complicates the interpretation of safety data.

          -  Prior chemotherapy for metastatic disease.

          -  >30 days of antiandrogen therapy monotherapy without androgen deprivation therapy.

          -  Life expectancy of 6 months or less.
      