Abiraterone Acetate Combined With Dutasteride for Metastatic Castrate Resistant Prostate Cancer

Phase II Trial of Abiraterone Acetate Combined With Dutasteride With Correlative Assessment of Tumor Androgen Levels and Androgen Receptor Sequence and Signaling at Baseline and at Progression

The purpose of this research study is to determine if the addition of dutasteride to a regimen with abiraterone acetate and prednisone will improve on therapy in patients with castrate-resistant prostate cancer and metastatic disease. This study will also help determine the side effects of the study treatment and how often they occur.

Patients will receive abiraterone acetate and prednisone orally, once daily for 2 months (2 cycles) on an outpatient basis. At the start of cycle 3, dutasteride will be taken once daily. Patients will return to the clinic on Day 14 of the first 3 cycles for routine blood tests.

Patients will come to the clinic every 12 weeks for a CT scan and/or x-ray of the chest, CT scan or MRI of the abdomen and pelvis, bone scan, and blood test for testosterone and other specialized blood test.

Inclusion Criteria:

• Diagnosis of adenocarcinoma of the prostate
• Castrate resistant disease
• Metastatic disease
• Normal organ and marrow function
• Subjects with partners of childbearing potential must be willing to use adequate methods of birth control

Exclusion Criteria:

• Uncontrolled intercurrent illness
• Uncontrolled hypertension
• Active or symptomatic viral hepatitis or chronic liver disease
• History of pituitary or adrenal dysfunction
• Clinically significant heart disease
• History of a different malignancy unless disease-free for at least 5 years
• Known brain metastasis
• History of gastrointestinal disorders
• Prior therapy with abiraterone acetate
• HIV-positive individuals on antiretroviral therapy
• Requirement for steroid use greater than the equivalent of 5 mg of prednisone daily
• Atrial fibrillation or other cardiac arrhythmia requiring therapy
• Thromboembolism in the last 6 months