Inclusion Criteria

          1. Histologically or cytologically confirmed adenocarcinoma of prostate

          2. Documented progressive metastatic CRPC based on at least one of the following
             criteria:

               1. PSA progression according to Prostate Cancer Working Group 3 (PCWG3) criteria

               2. Objective radiographic progression in soft tissue, according to modified Response
                  Evaluation Criteria In Solid Tumors (RECIST) or bone scans

          3. ECOG performance status of 0-2

          4. Have serum testosterone < 50 ng/dL. Subjects must continue primary androgen
             deprivation with an LHRH/GnRH analogue (agonist/antagonist) if they have not undergone
             orchiectomy

          5. Age >18 years

          6. Patients must have normal organ and marrow function as defined below:

               1. Absolute neutrophil count >1,500/cells/mm3

               2. Hemoglobin ≥ 9 g/dL

               3. Platelet count >100,000 x 109/microliter

               4. Serum creatinine <1.5 x upper limit of normal (ULN) or calculated creatinine
                  clearance ≥ 60 mL/min/1.73 m2 by Cockcroft-Gault

               5. Serum albumin ≥3.2 g/dL

               6. Serum potassium ≥3.5 mmol/L

          7. Patients must be able to take oral medication without crushing, dissolving or chewing
             tablets

          8. Ability to understand and the willingness to sign a written informed consent document

          9. Medications known to lower the seizure threshold (see list under prohibited
             medications) must be discontinued or substituted at least 4 weeks prior to study drug
             initiation

         10. Patients on stable dose of bisphosphonates or RANK-L inhibitor, Denosumab, which have
             been started no less than 4 weeks prior to treatment start, may continue on this
             medication

        Exclusion Criteria

          1. Liver Function

               1. If total bilirubin is >1.5 x ULN (NOTE: in subjects with Gilbert's syndrome, if
                  total bilirubin is >1.5 x ULN, measure direct and indirect bilirubin and if
                  direct bilirubin is within normal range, subject may be eligible) or

               2. Alanine (ALT) or aspartate (AST) aminotransferase >1.5xULN (or >5xULN for subject
                  with liver metastasis) concomitant with alkaline phosphatase >2.5xULN (or >5xULN
                  for subjects with bone or liver metastases) or

               3. Alanine (ALT or aspartate (AST) aminotransferase >2.5xULN (or >5xULN for subjects
                  with liver metastasis

          2. Use of investigational drugs (including vaccines) or implantation of invasive medical
             device ≤4 weeks or <5 half-lives of Cycle 1, Day 1 or current enrollment in
             investigational drug or device study

          3. Prior exposure to apalutamide. Prior exposure to abiraterone acetate and/or other
             CYP17 inhibitors, enzalutamide is allowed (but not preferred) only during the dose
             escalation period

          4. Prior chemotherapy for advanced prostate cancer. Prior chemotherapy for any other
             disease within 3 years

          5. Prior systemic beta-emitting bone-seeking radioisotopes (i.e. strontium-90)

          6. Pre-existing neuropathy ≥Grade 2

          7. Systemic azole treatment (e.g. Fluconazole, itracanozole) ≤2 weeks of Cycle 1 Day 1

          8. Use of potent inducers or inhibitors of CYP3A4 activity ≤2 weeks prior to Day 1 Cycle
             1

          9. History of adrenal insufficiency or hyperaldosteronism

         10. Active or symptomatic viral hepatitis

         11. Chronic liver disease

         12. Brain metastases or leptomeningeal disease

         13. Known allergies, hypersensitivity or intolerance to abiraterone acetate, apalutamide,
             docetaxel, dexamethasone, prednisone, or their excipients

         14. Use of herbal, alternative and food supplements (i.e. PC-Spes, Saw Palmetto, St John
             Wort, etc) must be discontinued before treatment start. Daily Multi-vitamin, calcium
             and Vitamin D is allowed

         15. Surgery or local prostatic intervention within 30 days of first dose. [Note: Any
             clinically relevant sequelae from surgery must have resolved prior to Day 1 Cycle 1]

         16. Radiation therapy for treatment of prostate cancer ≤4 weeks of Day 1 Cycle 1

         17. Current evidence of any of the following:

               1. Uncontrolled hypertension (defined as blood pressure of >150 mmHg systolic and/or
                  >100 mmHg diastolic on medication)

               2. Gastrointestinal disorder affecting absorption

               3. Active infection (e.g., human immunodeficiency virus [HIV] or viral hepatitis) or
                  other medical condition that would make prednisone/prednisolone (corticosteroid)
                  use contraindicated

               4. Any chronic medical condition requiring a higher dose of corticosteroid than 10
                  mg prednisone/prednisolone once daily

               5. Any condition that in the opinion of the investigator, would preclude
                  participation in this study

               6. Patients with baseline severe hepatic impairment (Child Pugh Class C)

         18. Severe or unstable angina, myocardial infarction, symptomatic congestive heart
             failure, arterial or venous thromboembolic events (e.g., pulmonary embolism,
             cerebrovascular accident including transient ischemic attacks), or clinically
             significant ventricular arrhythmias within 6 months prior to treatment start or New
             York Heart Association (NYHA) Class II to IV heart disease

         19. Seizure or known condition that may pre-dispose to seizure (including but not limited
             to prior stroke, transient ischemic attack, loss of consciousness within 1 year prior
             to randomization, brain arteriovenous malformation; or intracranial masses such as
             schwannomas and meningiomas that are causing edema or mass effect)

         20. Having partners of childbearing potential and not willing to use a method of birth
             control deemed acceptable by the principle investigator and chairperson during the
             study and for 1 week after last study drug administration