A Drug-Drug Interaction Study of Abiraterone Acetate Plus Prednisone With Dextromethorphan and Theophylline in Patients With Metastatic Castration-Resistant Prostate Cancer

Inclusion Criteria:

Histologically or cytologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation or small cell histology
Documented metastatic disease
Documented prostate specific antigen (PSA) progression according to Prostate Cancer Working Group 2 criteria, with PSA value >=2 ng/mL despite medical or surgical castration, or prostate cancer progression documented by radiographic progression according to Response Evaluation Criteria In Solid Tumors criteria
Surgically or medically castrated with testosterone levels of <50 ng/dL
Eastern Cooperative Oncology Group (ECOG) Performance Status of <=2
Group A only: genomic testing at screening indicating CYP2D6 extensive metabolizer status
Protocol-defined laboratory values

Exclusion Criteria:

Serious or uncontrolled co-existent non-malignant disease, including active and uncontrolled infection
Group A only: genomic testing at screening indicating CYP2D6 non-extensive metabolizer status, or prior treatment with dextromethorphan-containing medication or any medication that is a strong inhibitor or inducer of CYP2D6 within 5 half-lives of that drug or 7 days, whichever is longer, prior to Cycle 1 Day -8
Group B only: prior treatment with theophylline or any medication that is a strong inhibitor or inducer of CYP1A2 within 5 half-lives of that drug or 7 days, whichever is longer, prior to Cycle 1 Day -8
Abnormal liver function
Uncontrolled hypertension (repeated systolic blood pressure >=160 mmHg, or diastolic blood pressure >=95 mmHg)
Active or symptomatic viral hepatitis or chronic liver disease
Known brain metastasis
History of pituitary or adrenal dysfunction
Clinically significant heart disease as evidenced by myocardial infarction, or arterial thrombotic events in the past 6 months, severe or unstable angina, or New York Heart Association Class III or IV heart disease or cardiac ejection fraction measurement of <50% at baseline
History of gastrointestinal disorders (medical disorders or extensive surgery) which may interfere with the absorption of the study drug
Surgery or local prostatic intervention within 28 days of the first dose, and any clinically relevant sequelae from the surgery must have resolved prior to Cycle 1 Day 1
Radiotherapy or immunotherapy within 28 days, or single fraction of palliative radiotherapy within 14 days of administration of Cycle 1 Day 1
Any acute toxicities due to prior therapy that have not resolved
Current enrollment in an investigational drug or device study or participation in such a study within 28 days of Cycle 1 Day 1
Previous abiraterone acetate or other investigational CYP17 inhibitor (eg, TAK-700)