Inclusion Criteria:

          -  Histologically or cytologically confirmed adenocarcinoma of the prostate without
             neuroendocrine differentiation or small cell features

          -  Presence of metastatic disease that can be biopsied by any methodology applicable

          -  Ongoing androgen deprivation therapy with a gonadotropin releasing hormone (GnRH)
             analogue or orchiectomy (i.e., surgical or medical castration)

          -  Serum testosterone level =< 50 ng/dL at the screening visit

          -  Progressive disease defined as one or more of the following three criteria (NOTE:
             Patients who received an antiandrogen must demonstrate disease progression following
             discontinuation of antiandrogen):

               -  PSA progression defined by a minimum of two rising PSA levels with an interval of
                  >= 1 weeks between each determination. The PSA value at the screening visit
                  should be >= 2 ng/mL

               -  Soft tissue disease progression as defined by the Response Evaluation Criteria in
                  Solid Tumors (RECIST)

               -  Bone disease progression defined by two or more new lesions on bone scan

          -  Patients previously treated with chemotherapy must have no more than two prior
             chemotherapy regimens for the treatment of metastatic prostate cancer

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0-1

          -  Serum albumin >= 3.0 g/dL

          -  Serum potassium >= 3.5 mmol/L

          -  Estimated life expectancy of >= 6 months

          -  Able to swallow the study drug and comply with study requirements

          -  Willing and able to give informed consent

          -  Tumor specimen obtained prior to treatment initiation by interventional radiology
             guided biopsy will be interrogated per immunohistochemistry (IHC) and features should
             be as follows for a patient to be eligible

               -  Overexpression of androgen receptor (AR)-C terminal and AR-N terminal and PTEN
                  with lack of ARV7 expression along with and ki67 =<10%

               -  No combined RB loss and p53 mutation and

               -  No expression of neuroendocrine markers CD56 and chromogranin (all markers
                  assessed by standardized IHC protocols)

          -  Agrees to use a condom (even men with vasectomies) and another effective method of
             birth control if he is having sex with a woman of childbearing potential or agrees to
             use a condom if he is having sex with a woman who is pregnant while on study drug and
             for 3 months following the last dose of study drug. Must also agree not to donate
             sperm during the study and for 3 months after receiving the last dose of study drug

               -  The methods must consist of a condom and the use of another barrier method (such
                  as a diaphragm or cervical/vault caps) with a spermicidal agent. Your female
                  partner can choose to use an intrauterine device or system (intrauterine device
                  [IUD] or intrauterine system [IUS]) or use birth control pills, injections, or
                  implants instead of a barrier method

        Exclusion Criteria:

          -  Known allergy to the study drugs or any of its components

          -  Severe, concurrent disease, infection, or co-morbidity that, in the judgment of the
             investigator, would make the patient inappropriate for enrollment or other medical
             condition that would make prednisone/prednisolone (corticosteroid) use contraindicated

          -  Known metastases to the brain

          -  Absolute neutrophil count < 1000/uL at the screening visit

          -  Platelet count =< 100,000 x 10^9/uL at the screening visit

          -  Hemoglobin < 9 g/dL at the screening visit at the screening visit

          -  NOTE: patients may not have received any growth factors or blood transfusions within
             seven days of the hematologic laboratory values obtained at the screening visit

          -  Total bilirubin (Tbili) > 1.5 times the upper limit of normal at the screening visit

          -  Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 2.5 times the
             upper limit of normal at the screening visit

          -  Creatinine (Cr) > 2 mg/dL at the screening visit

          -  History of another malignancy within the previous 2 years with > 30 % probability of
             relapse other than curatively treated non-melanomatous skin cancer

          -  Treatment with androgen receptor antagonists (bicalutamide, flutamide, nilutamide),
             5-alpha reductase inhibitors (finasteride, dutasteride), estrogens, chemotherapy, or
             biologic therapy within 4 weeks of enrollment (day 1 visit)

          -  Radiation therapy within 3 weeks (if single fraction of radiotherapy within 2 weeks)
             of enrollment (day 1 visit)

          -  Planned palliative procedures for alleviation of bone pain such as radiation therapy
             or surgery

          -  Structurally unstable bone lesions suggesting impending fracture

          -  History of seizure or any condition that may increase the patient's seizure risk.
             Also, history of loss of consciousness or transient ischemic attack within 12 months
             of day 1

          -  Clinically significant cardiovascular disease including:

               -  Myocardial infarction within 6 months

               -  Uncontrolled angina within 6 months

               -  Congestive heart failure New York Heart Association (NYHA) class 3 or 4 in the
                  past, or history of anthracycline or anthracenedione (mitoxantrone) treatment,
                  unless a screening echocardiogram or multi-gated acquisition scan (MUGA)
                  performed within three months results in a left ventricular ejection fraction
                  that is >= 45%

               -  History of clinically significant ventricular arrhythmias (e.g., ventricular
                  tachycardia, ventricular fibrillation, torsades de pointes)

               -  Prolonged corrected QT interval by the Fridericia correction formula (QTcF) on
                  the screening electrocardiogram (ECG) > 470 msec

               -  History of Mobitz II second degree or third degree heart block without a
                  permanent pacemaker in place

               -  Hypotension (systolic blood pressure < 86 millimeters of mercury or bradycardia
                  with a heart rate of < 50 beats per minute on any ECG taken at the screening
                  visit

               -  Bradycardia with a heat rate of < 50 beats per minutes in the screening ECG,
                  unless pharmaceutically induced and reversible

               -  Chronically uncontrolled hypertension as indicated by consistently elevated
                  resting blood pressure (systolic blood pressure > 170 mmHg or diastolic blood
                  pressure > 105 mmHg) during screening

          -  Have used or plan to use from 30 days prior to enrollment (day 1 visit) through the
             end of the study the following medications known to lower the seizure threshold:

               -  Aminophylline/theophylline

               -  Atypical antipsychotics (e.g., clozapine, olanzapine, risperidone, ziprasidone)

               -  Bupropion

               -  Insulin

               -  Lithium

               -  Pethidine

               -  Phenothiazine antipsychotics (e.g., prochlorperazine [compazine], chlorpromazine,
                  mesoridazine, thioridazine)

               -  Tricyclic and tetracyclic antidepressants (e.g., amitriptyline, desipramine,
                  doxepin, imipramine, maprotiline, mirtazapine)

          -  Prior use of ketoconazloe, enzalutamide, abiraterone or apalutamide or participation
             in a previous clinical trial of ketoconazloe,enzalutamide, abiraterone or apalutamide
             unless within the neoadjuvant setting

          -  Use of an investigational agent within 4 weeks of enrollment (day 1)

          -  Gastrointestinal disorder affecting absorption (e.g., gastrectomy)

          -  Major surgery within 4 weeks prior to enrollment (day 1)

          -  History of significant bleeding disorder unrelated to cancer, including:

               -  Diagnosed congenital bleeding disorders (e.g., von Willebrand's' disease)

               -  Diagnosed acquired bleeding disorder within one year (e.g., acquired anti-factor
                  VIII antibodies)

               -  History of gastrointestinal (GI) bleeding within one year

          -  Known active or symptomatic viral hepatitis or chronic liver disease

          -  Known history of pituitary or adrenal dysfunction

          -  Baseline moderate and severe hepatic impairment (Child Pugh class B & C)