S1014 Abiraterone Acetate in Treating Patients With Prostate Cancer Who Have Undergone Initial Hormone Therapy

DISEASE CHARACTERISTICS:

Histologically or cytologically proven diagnosis of adenocarcinoma of the prostate

Metastatic (M1) disease as evidenced by soft tissue and/or bony metastases at the time of initiation of androgen-deprivation therapy (ADT)

Must have at least one of the following:

Visceral disease (liver, lung, other viscera)
Bone metastases to sites in either the axial (spine, pelvis, ribs, or skull) and/or the appendicular (clavicle, humerus, or femur) skeleton
Distant lymph node disease (e.g., above the aortic bifurcation, etc.)
No small cell or neuroendocrine prostate cancer

Patients must be receiving ADT (e.g., gonadotropin-releasing hormone [GNRH] antagonist, with or without antiandrogen) prior to entering this study

Degarelix, a FDA-approved GNRH antagonist, is an acceptable form of ADT
Bilateral surgical orchiectomy is also acceptable

Suboptimal response to ADT induction as defined by the following criteria:

Declining PSA (current PSA is less than the PSA prior to starting ADT) that fails to reach 4 ng/mL or below despite continuous ADT

PSA of > 4 ng/mL must be observed between 6-12 months after the initiation of ADT

Documentation of failure to achieve this PSA of ≤ 4 ng/mL must be within 28 days of registration

The PSA must be obtained after any applicable antiandrogen washout period
If the PSA is declining or stable (defined as a PSA rise ≤ 0.1 ng/mL from nadir) and the patient is on an antiandrogen, they must remain on the antiandrogen
Patients with stable or declining PSA who have had previous antiandrogen exposure, but are not taking an antiandrogen at the time of registration, must wait at least 6 weeks from the last antiandrogen dose before registration and still demonstrate a stable or falling PSA which is > 4 ng/mL by month 12, in order to be eligible
If the PSA is rising and they are on an antiandrogen, formal antiandrogen washout must be performed (4 weeks for flutamide and 6 weeks for bicalutamide and nilutamide with no evidence of a falling PSA after washout)
No patients with radiographic progression when compared to available imaging studies performed prior to starting the GNRH agonist/antagonist therapy
Patients who have measurable disease must have radiographic assessment (at least an abdominal/pelvic CT scan) within 28 days prior to registration
Non-measurable disease must be assessed (i.e., bone scan) within 42 days prior to registration

No patients with a history of brain metastases or who currently have treated or untreated brain metastases

Patients with clinical evidence of brain metastases must have a brain CT scan or MRI negative for metastatic disease within 56 days prior to registration

PATIENT CHARACTERISTICS:

Zubrod performance status 0-2
ANC ≥ 1,500/μL
Platelet count ≥ 100,000/μL
Hemoglobin ≥ 10 g/dL
Serum creatinine ≤ 1.5 times the upper limit of normal (ULN) OR creatinine clearance ≥ 60 mL/min
Bilirubin ≤ 1.5 times ULN (unless documented Gilbert disease)
AST and ALT < 1.5 times ULN
Potassium ≥ 3.5 mmol/L
Patient must have a testosterone value of < 50 ng/dL obtained within 28 days prior to registration

Patients must have controlled blood pressure defined as systolic blood pressure < 160 mm Hg and diastolic blood pressure < 95 mm Hg

Patients with a history of hypertension are eligible provided blood pressure is controlled by anti-hypertensive treatment
Patients who have partners of child-bearing potential must be willing to use a method of birth control with adequate barrier protection during the study and for 1 week after the last study drug administration
Must be able to take oral medication without crushing, dissolving, or chewing tablets
Patients must not have a history of gastrointestinal disorders (medical disorders or extensive surgery) that may interfere with the absorption of abiraterone acetate

No other prior malignancy is allowed except for any of the following:

Adequately treated basal cell or squamous cell skin cancer
Adequately treated stage I or II cancer from which the patient is currently in complete remission
Any other cancer from which the patient has been disease-free for 5 years

No patients with active or symptomatic viral hepatitis or chronic liver disease

No moderate (Child-Pugh B) or severe (Child-Pugh C) hepatic impairment

No history of NYHA class III or IV heart failure

Patients must have LVEF ≥ 50%
No known allergies, hypersensitivity, or intolerance to abiraterone acetate, prednisone, or their excipients

PRIOR CONCURRENT THERAPY:

See Disease Characteristics

Patients with a history of prior neoadjuvant or adjuvant GNRH agonist/antagonist therapy (related to previous surgery or radiation) are eligible provided they finished this therapy at least two years prior to registration

Prior enrollment to SWOG-S0925 (either arm) is not exclusionary
At least 6 weeks since prior and no concurrent finasteride or dutasteride
At least 28 days since prior radiotherapy or surgery and recovered
At least 4 weeks since prior investigational products

At least 4 weeks since prior flutamide (6 weeks for bicalutamide and nilutamide) with no evidence of a falling PSA

No other concurrent oral antiandrogen
No prior or concurrent cytotoxic chemotherapy or radiopharmaceuticals for prostate cancer
No prior or concurrent ketoconazole for the treatment of prostate cancer
Not requiring more than 10 mg a day of prednisone for another medical indication
Not planning to receive any concurrent cytotoxic chemotherapy, immunotherapy, surgery, or radiotherapy during protocol treatment
No concurrent hormonal-acting agents, including diethylstilbestrol/DES, aldosterone, PC-SPES, or spironolactone
No concurrent antifungal medication (e.g., fluconazole or itraconazole)
No medications that alter cardiac conduction
No prior Provenge (sipuleucel-T)