A Study to Evaluate Serum Testosterone Levels in Patients With Metastatic Castration-Resistant Prostate Cancer

This is 12-week, open-label study of abiraterone acetate in at least 50 patients with
metastatic castration-resistant prostate cancer. The primary endpoint is total testosterone
at pharmacokinetic steady-state. Additional secondary endpoints include safety assessments,
PSA and pharmacokinetic measurements

Inclusion Criteria:

1. Written informed consent obtained prior to any study-related procedure being
performed

2. Male subjects at least 18 years of age or older at time of consent

3. Pathologically confirmed adenocarcinoma of the prostate

4. Ongoing therapy with a GnRH agonist or antagonist AND serum testosterone level <50
ng/dL at screening

5. Metastatic disease documented by computed tomography (CT)/ magnetic resonance imaging
(MRI) or bone scan. Imaging obtained within 42 days prior to the start of study
medication will be accepted.

6. Meeting disease progression according to the recommendations of the prostate cancer
working group 2 by one of the following criteria:

- Two rises of PSA (taken a minimum of 1 week apart) from a baseline measurement
of at least 2 ng/mL,

- Imaging progression (CT/MRI) by RECIST criteria

- Nuclear scan progression by new lesion.

7. Discontinuation of flutamide or nilutamide, and other anti-androgens at least 4 weeks
prior to the start of study medication; discontinuation of bicalutamide at least 6
weeks prior to start of study medication.

8. Discontinuation of Radiotherapy > 4 weeks prior to start of study medication.

9. ECOG performance status of 0-1 at screening

10. Screening blood counts of the following:

- Absolute neutrophil count > 1500/µL

- Platelets > 100,000/µL

- Hemoglobin > 9 g/dL

11. Screening chemistry values of the following:

- ALT and AST < 2.5 x ULN

- Total bilirubin < 1.5 x ULN

- Creatinine< 1.5 x ULN

- Albumin > 3.0 g/dL

12. Potassium > 3.5 mmol/L

13. Life expectancy of at least 6 months at screening

14. Subject is willing and able to comply with all protocol requirements assessments

15. Agrees to protocol-defined use of effective contraception.

Exclusion Criteria:

1. History of impaired pituitary or adrenal gland function

2. Prior therapy with abiraterone acetate, orteronel, ketoconazole or any other CYP17
inhibitor

3. Prior therapy with enzalutamide

4. Prior use of experimental androgen receptor antagonist

5. Previous exposure to Ra-223:Xofigo

6. Previous chemotherapy

7. Initiation of bisphosphonate or denosumab therapy within 30 days prior to the start
of study medication. Patients who are on a stable dose of these medications for at
least 30 days at the time of starting study drug are eligible.

8. Therapy with estrogen within 30 days prior to the start of study medication

9. Use of systemic glucocorticoids equivalent to > 10 mg of prednisone daily; patients
who have discontinued or have reduced dose to < 10 mg prednisone within 14 days prior
to the start of study medication will be eligible

10. Prior use of any herbal products that may decrease PSA levels (eg., saw palmetto)
within 30 days of start of study medication

11. Known metastases to the brain or CNS involvement

12. History of other malignancy within the previous 2 years

13. Major surgery within 30 days prior to the start of study medication

14. Blood transfusion within 30 days of screening

15. Serious, persistent infection within 14 days of the start of study medication

16. Persistent pain that requires the use of a narcotic analgesic

17. Known gastrointestinal disease or condition that may impair absorption

18. Treatment with any investigational drug within 4 weeks prior to Day -1 of the study.

19. Known history of human immunodeficiency virus (HIV) or seropositive test for
hepatitis C virus or hepatitis B virus

20. Have poorly controlled diabetes.

21. Uncontrolled hypertension

22. History of New York Heart Association (NYHA) class III or IV heart failure

23. Serious concurrent illness, including psychiatric illness, that would interfere with
study participation

24. Inability to swallow tablets whole

25. Known hypersensitivity to any excipients in study medications

26. Moderate to severe hepatic impairment (Child-Pugh Classes B and C)