Randomized, Open-Label Study of Abiraterone Acetate (JNJ-212082) Plus Prednisone With or Without Exemestane in Postmenopausal Women With ER+ Metastatic Breast Cancer Progressing After Letrozole or Anastrozole Therapy

1. Woman *18 years of age and postmenopausal determined by one of the following:
*bilateral, surgical oophorectomy
*age *60 years
*age <60 years, with amenorrhea *24 months and follicle-stimulating hormone and luteinizing hormone concentrations within postmenopausal range ;2. Subjects with ER+, Her2- metastatic breast cancer, confirmed within 7
days before randomization with FFPE tissue from either primary or
metastatic breast cancer site. If the tissue block is obtained from a
metastatic site, it should be obtained during or within 6 months of
discontinuing anastrozole or letrozole.;3. Subjects with disease confined only to bone may be included.;4. Disease must have been sensitive to anastrozole or letrozole therapy
prior to disease progression. Sensitivity to anastrozole or letrozole is
defined as either stable disease or better for *6 months in the
metastatic setting or relapse free for *2 years in the adjuvant setting.;5. No more than two prior lines of therapy in the metastatic setting, of
which no more than one was chemotherapy [Note: Simultaneous
combination treatment is considered one line of therapy.];6. Eastern Cooperative Oncology Group (ECOG) performance status score
of *1;7. Clinical laboratory values during Screening:
*hemoglobin *10.0 g/dL
*neutrophils *1.5 x 10^9/L
*platelets *100 x 10^9/L
*total bilirubin *1.5 x upper limit of normal (ULN)
*alanine (ALT) and aspartate (AST) aminotransferase *2.5xULN
*alkaline phosphatase *6xULN unless bone metastases with no liver
disorder
*serum creatinine <1.5xULN or creatinine clearance *50 mL/min
*serum potassium *3.5 mM
*serum albumin *3.0 g/dL
*prothrombin time (PT) and partial thromboplastin time (PTT) within
normal limits [Exception: PT and international normalized ratio (INR)
will be abnormally prolonged in subjects taking warfarin.];8. Systolic blood pressure <160 mm Hg and diastolic blood pressure <95
mm Hg [Note: Hypertension controlled by antihypertensive therapy is
permitted].;9. Cardiac ejection fraction *50% measured by MUGA or ECHO done
within 4 weeks before randomization;10. If receiving a bisphosphonate or denosumab, dose must have been
stable for at least 2 doses before randomization.;11. Willing and able to adhere to prohibitions and restrictions specified in
this protocol;12. Signs an informed consent document within 4 weeks before
randomization indicating she understands the purpose of and procedures
required for the study and is willing to participate in the study;13. Signs the informed consent document within 4 weeks before
randomization for pharmacogenomics research indicating willingness to
participate in the pharmacogenomic component of the study, where local
regulations permit. [Note: Refusal to give consent for this component
does not exclude a subject from participation in this clinical study.]

1. Prior treatment with exemestane, ketoconazole, aminoglutethimide, or a CYP17 inhibitor;2. Anticancer immunotherapy or investigational agent within 4 weeks before randomization, or anticancer radiotherapy (except palliative) or anticancer endocrine therapy within 2 weeks before randomization [Note: Potential subjects must not have taken anastrozole, letrozole, fulvestrant, or any chemotherapy for at least 2 weeks (bevacizumab for at least 3 weeks) before study entry.];3. Serious or uncontrolled nonmalignant disease, including active or uncontrolled infection;4. Clinical or biochemical evidence of hyperaldosteronism or hypopituitarism;5. Any condition that, in the opinion of the investigator, would compromise the well-being of the patient or that could prevent, limit, or confound the protocol-specified assessments;6. Major thoracic or abdominal surgery or significant traumatic injury with 4 weeks before randomization or plans surgery during study participation or within 4 weeks after the last dose of study drug [Note: Patients with planned surgical procedures to be conducted under local anesthesia are not excluded from the study.];7. Persistent *Grade 2 toxicity from any cause [Note: Chemotherapy-induced alopecia and Grade 2 peripheral neuropathy are allowed.];8. Symptomatic central nervous system disease or leptomeningeal disease ;9. Gastrointestinal disorder interfering with study drug absorption ;10. Active or uncontrolled autoimmune disease that may require corticosteroid therapy;11. Active or symptomatic viral hepatitis or chronic liver disease;12. History of clinically significant heart disease, ie, myocardial infarction or arterial thrombotic event within 6 months, severe or unstable angina, or New York Heart Association Class III or IV heart disease;13. Known allergies, hypersensitivity, or intolerance to abiraterone acetate, exemestane, prednisone, or their excipients;14. Contraindications to the use of exemestane or prednisone per local prescribing information;15. Received an investigational drug (including investigational vaccines) or used an invasive investigational medical device within 4 weeks before the planned first dose of study drug or is currently enrolled in an investigational study