Study was terminated prematurely in all investigational study centers upon recommendation from the study's Data Monitoring Committee (DMC).

Study was stopped due to lack of efficacy.

A Phase 2, 2 part trial to evaluate the safety and efficacy of galeterone in castration resistant prostate cancer (CRPC) patients.

This trial will be split into two parts. The purpose of Part 1 will be to confirm dose and target patient population and Part 2 will be expansion of the dose and patient population selected in Part 1. For eligible patients, there will be an optional extension dosing following the completion of Part 1 or Part 2 of the trial.

Obtaining of informed consent and screening may be performed up to 28 days prior to enrollment. Each patient will be able to receive his specified regimen for 3 consecutive cycles. Each cycle consists of 28 days (approximately 1 mo.). End of Cycle 3 visit assessments will be used to determine outcome and dosing may continue up to an additional 2 weeks until the results of all assessments are obtained. Eligible patients may continue treatment in an optional extension period following the completion of the primary parts of this trial.

Inclusion Criteria:

1. Histologically or cytologically confirmed adenocarcinoma of the prostate
2. Ongoing androgen blockade demonstrated by serum testosterone concentration of less than 50 ng/dL
3. Demonstration of progression while on androgen blockade
4. Eastern Cooperative Oncology Group (ECOG) Performance Status <2

Exclusion Criteria:

1. Depending upon patient prior treatment the following apply:

   • Prior treatment with CYP17 inhibitors or AR antagonists (e.g. abiraterone, TAK-700, ARN-509, ketoconazole*, enzalutamide, or galeterone) - Treatment naïve only
   • Prior treatment with CYP17 inhibitors (e.g. TAK-700, ketoconazole*) or AR antagonists (e.g. enzalutamide, ARN-509,) or galeterone - abiraterone refractory only
   • Prior treatment with CYP17 inhibitors (e.g. abiraterone, TAK-700, ketoconazole*) or AR antagonists (e.g. ARN -509) or galeterone - enzalutamide refractory only

2. Prior chemotherapy (unless allowed for some study arms)

3. Treatment with non-steroidal oral antiandrogens within 4 weeks of enrollment

4. Prior use of any chronic systemic glucocorticoids .

5. Prior radiation therapy within 3 weeks and radionuclide therapy within 8 weeks of enrollment

6. Prior treatment with Alpharadin® (Xofigo®)

7. Treatment with anti arrhythmia therapy for ventricular arrhythmia < 4 weeks prior to enrollment

8. Treatment with Coumadin® or other anti-coagulant therapy (except aspirin) < 4 weeks prior to enrollment

9. Severe systemic diseases or active uncontrolled illnesses.

10. Abnormal heart function

11. Liver metastases

12. Brain metastases (unless stable disease >3 mos. by scan without additional CNS-directed therapy)

13. The patient has known allergy to any of the treatment components

14. Any physical or mental condition or social situation that in the opinion of the Investigator may interfere with the patient's ability to comply with the trial procedures

15. History of excessive alcohol consumption

16. Use of any substance known to cause AME