An Abiraterone Acetate Plus Prednisone Drug-Drug Interaction Study 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)